Sally McArthur

Colloidal crystal based plasma polymer patterning to control Pseudomonas aeruginosa attachment to surfaces

Publisher: American Vacuum Society

Date: 12-2015

DOI: 10.1116/1.4936071

Abstract: Biofilm formation on medical implants and subsequent infections are a global problem. A great deal of effort has focused on developing chemical contrasts based on micro- and nanopatterning for studying and controlling cells and bacteria at surfaces. It has been known that micro- and nanopatterns on surfaces can influence biomolecule adsorption, and subsequent cell and bacterial adhesion. However, less focus has been on precisely controlling patterns to study the initial bacterial attachment mechanisms and subsequently how the patterning influences the role played by biomolecular adsorption on biofilm formation. In this work, the authors have used colloidal self-assembly in a confined area to pattern surfaces with colloidal crystals and used them as masks during allylamine plasma polymer (AAMpp) deposition to generate highly ordered patterns from the micro- to the nanoscale. Polyethylene glycol (PEG)-aldehyde was grafted to the plasma regions via “cloud point” grafting to prevent the attachment of bacteria on the plasma patterned surface regions, thereby controlling the adhesive sites by choice of the colloidal crystal morphology. Pseudomonas aeruginosa was chosen to study the bacterial interactions with these chemically patterned surfaces. Scanning electron microscope, x-ray photoelectron spectroscopy (XPS), atomic force microscopy, and epifluorescence microscopy were used for pattern characterization, surface chemical analysis, and imaging of attached bacteria. The AAMpp influenced bacterial attachment because of the amine groups displaying a positive charge. XPS results confirm the successful grafting of PEG on the AAMpp surfaces. The results showed that PEG patterns can be used as a surface for bacterial patterning including investigating the role of biomolecular patterning on bacterial attachment. These types of patterns are easy to fabricate and could be useful in further applications in biomedical research.

Some changes, but still communicating exciting key insights from the biointerface

Publisher: American Vacuum Society

Date: 12-2017

DOI: 10.1116/1.5018515

Biotic Interactions as Mediators of Biological Invasions: Insights from South Africa

Publisher: Springer International Publishing

Date: 2020

DOI: 10.1007/978-3-030-32394-3_14

Molecularly imprinted polymers for sample preparation and biosensing in food analysis: Progress and perspectives

Publisher: Elsevier BV

Date: 05-2017

DOI: 10.1016/J.BIOS.2017.01.018

Abstract: Molecularly imprinted polymers (MIPs) are biomimetics which can selectively bind to analytes of interest. One of the most interesting areas where MIPs have shown the biggest potential is food analysis. MIPs have found use as sorbents in s le preparation attributed to the high selectivity and high loading capacity. MIPs have been intensively employed in classical solid-phase extraction and solid-phase microextraction. More recently, MIPs have been combined with magnetic bead extraction, which greatly simplifies s le handling procedures. Studies have consistently shown that MIPs can effectively minimize complex food matrix effects, and improve recoveries and detection limits. In addition to s le preparation, MIPs have also been viewed as promising alternatives to bio-receptors due to the inherent molecular recognition abilities and the high stability in harsh chemical and physical conditions. MIPs have been utilized as receptors in biosensing platforms such as electrochemical, optical and mass biosensors to detect various analytes in food. In this review, we will discuss the current state-of-the-art of MIP synthesis and applications in the context of food analysis. We will highlight the imprinting methods which are applicable for imprinting food templates, summarize the recent progress in using MIPs for preparing and analysing food s les, and discuss the current limitations in the commercialisation of MIPs technology. Finally, future perspectives will be given.

Fabrication of a Biocompatible Liquid Crystal Graphene Oxide–Gold Nanorods Electro‐ and Photoactive Interface for Cell Stimulation

Publisher: Wiley

Date: 06-03-2019

DOI: 10.1002/ADHM.201801321

Abstract: For decades, electrode-tissue interfaces are pursued to establish electrical stimulation as a reliable means to control neuronal cells behavior. However, spreading of electrical currents in tissues limits its spatial precision. Thus, optical cues, such as near-infrared (NIR) light, are explored as alternatives. Presently, NIR stimulation requires higher energy input than electrical methods despite introduction of light absorbers, e.g., gold nanoparticles. As potential solution, NIR and electrical costimulation are proposed but with limited interfaces capable of sustaining this stimulation technique. Here, a novel electroactive nanocomposite with photoactive properties in the NIR range is constructed by N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride/N-hydroxysulfosuccinimide sodium (EDC)/NHS conjugation of liquid crystal graphene oxide (LCGO) to protein-coated gold nanorods (AuNR). The liquid crystal graphene oxide-gold nanorod nanocomposite (LCGO-AuNR) is fabricated into a hydrophilic electrode-coating via drop-casting, making it appropriate for versatile electrode-tissue interface fabrication. UV-vis spectrophotometry results demonstrate that LCGO-AuNR presents an absorbance peak at 798 nm (NIR range). Cyclic voltammetry measurements further confirm its electroactive capacitive properties. Furthermore, LCGO-AuNR coating supports cell adhesion, proliferation, and differentiation of NG108-15 neuronal cells. This biocompatible interface is anticipated, with ideal electrical and optical properties for NIR and electrical costimulation, to enable further development of the technique for energy-efficient and precise neuronal cell modulation.

Effects of laser-exposed gold nanorods on biochemical pathways of neuronal cells

Publisher: SPIE

Date: 07-12-2013

DOI: 10.1117/12.2033575

Assessing multiple predator, diurnal and search area effects on predatory impacts by ephemeral wetland specialist copepods

Publisher: Springer Science and Business Media LLC

Date: 29-11-2019

DOI: 10.1007/S10452-019-09735-Y

Abstract: Predator–prey interaction strengths can be highly context-dependent. In particular, multiple predator effects (MPEs), variations in predator sex and physical habitat characteristics may affect prey consumption rates and thus the persistence of lower trophic groups. Ephemeral wetlands are transient ecosystems in which predatory copepods can be numerically dominant. We examine the interaction strengths of a specialist copepod Paradiaptomus lamellatus towards mosquito prey in the presence of conspecifics using a functional response approach. Further, we examine sex variability in predation rates of P. lamellatus under circadian and surface area variations. Then, we assess the influence of a co-occurring heterospecific predatory copepod, Lovenula raynerae , on total predation rates. We demonstrate MPEs on consumption, with antagonism between conspecific P. lamellatus predatory units evident, irrespective of prey density. Furthermore, we show differences between sexes in interaction strengths, with female P. lamellatus significantly more voracious than males, irrespective of time of day and experimental arena surface area. Predation rates by P. lamellatus were significantly lower than the heterospecific calanoid copepod L. raynerae , whilst heterospecific copepod groups exhibited the greatest predatory impact. Our results provide insights into the predation dynamics by specialist copepods, wherein species density, ersity and sex affect interaction strengths. In turn, this may influence population-level persistence of lower trophic groups under shifting copepod predator composition.

Towards proteomics-on-chip: The role of the surface

Publisher: Royal Society of Chemistry (RSC)

Date: 2011

DOI: 10.1039/C005236A

Abstract: Miniaturisation is revolutionary to high-throughput proteomics. These technologies have gained much interest in the past decade, as they allow for sensitive parallel analysis of small amounts of biological materials. This review describes the state of the art of proteomics-on-chip, with a particular focus on the fundamental proteomics-on-chip challenges. The important role of bio-interfacial interactions and strategies to control them are presented. Various coating methodologies for on-chip protein eptide separation are reviewed to provide an overview of the principles of protein-resistant and protein immobilisation coatings, and their effectiveness.

Synthesis and Characterization of Polypyrrole-Coated Sulfur-Rich Latex Particles:  New Synthetic Mimics for Sulfur-Based Micrometeorites

Publisher: American Chemical Society (ACS)

Date: 26-04-2006

DOI: 10.1021/CM0601741

Development of a microtiter plate-based glycosaminoglycan array for the investigation of glycosaminoglycan-protein interactions

Publisher: Oxford University Press (OUP)

Date: 03-09-2009

DOI: 10.1093/GLYCOB/CWP132

Electrospun Nanofibers as Dressings for Chronic Wound Care: Advances, Challenges, and Future Prospects

Publisher: Wiley

Date: 28-03-2014

DOI: 10.1002/MABI.201300561

Abstract: Chronic non-healing wounds show delayed and incomplete healing processes and in turn expose patients to a high risk of infection. Treatment currently focuses on dressings that prevent microbial infiltration and keep a balanced moisture and gas exchange environment. Antibacterial delivery from dressings has existed for some time, with responsive systems now aiming to trigger release only if infection occurs. Simultaneously, approaches that stimulate cell proliferation in the wound and encourage healing have been developed. Interestingly, few dressings appear capable of simultaneously impairing or treating infection and encouraging cell proliferation/wound healing. Electrospinning is a simple, cost-effective, and reproducible process that can utilize both synthetic and natural polymers to address these specific wound challenges. Electrospun meshes provide high-surface area, micro-porosity, and the ability to load drugs or other biomolecules into the fibers. Electrospun materials have been used as scaffolds for tissue engineering for a number of years, but there is surprisingly little literature on the interactions of fibers with bacteria and co-cultures of cells and bacteria. This Review examines the literature and data available on electrospun wound dressings and the research that is required to develop smart multifunctional wound dressings capable of treating infection and healing chronic wounds.

Covalent Coupling and Characterization of Supported Lipid Layers

Publisher: American Chemical Society (ACS)

Date: 23-08-2003

DOI: 10.1021/LA026928H

XPS and surface-MALDI-MS characterisation of worn HEMA-based contact lenses

Publisher: Elsevier BV

Date: 12-2001

DOI: 10.1016/S0142-9612(01)00166-1

Abstract: XPS and MALDI-MS were used to analyse initial adsorption events in the fouling of HEMA-based contact lenses. All of the lenses tested accumulated tear film deposits within 10 min of wear. XPS indicated the presence of mainly proteinaceous deposits, with indications of some contributions by mucins or lipids on some lenses and the nature of the deposit being influenced by the lens chemistry. MALDI-MS detected the presence of surface-adsorbed species with molecular weights < 15 kDa. While lysozyme could be identified by comparison of MALDI-MS signals with known protein mass and assignments are suggested for some other signals, several other species, with MWs less than that of lysozyme, could not be identified as no ocular proteins with corresponding MWs had been reported in previous biochemical tear film analyses. These species, and others, were also detected in MALDI-MS analysis of reflex tear film, suggesting that the adsorbed unidentified species were not simply products of surface-induced dissociation of adsorbing higher-MW proteins. This short-term wear study detected rapid interface conversion and demonstrated the utility and surface sensitivity of XPS and MALDI-MS in characterising contact lens deposits at the initial stages when sub-monolayer adsorbed amounts are present on lenses.

The effect of metal microstructure on the initial attachment ofEscherichia colito 1010 carbon steel

Publisher: Informa UK Limited

Date: 09-2013

DOI: 10.1080/08927014.2013.820826

Abstract: Metallurgical features have been shown to play an important role in the attachment of microorganisms to metal surfaces. In the present study, the influence of the microstructure of as-received (AR) and heat-treated (HT) 1010 carbon steel on the initial attachment of bacteria was investigated. Heat treatment was carried out with the aim of increasing the grain size of the carbon steel coupons. Mirror-polished carbon steel coupons were immersed in a minimal medium inoculated with Escherichia coli (ATCC 25922) to investigate the early (15, 30 and 60 min) and relatively longer-term (4 h) stages of bacterial attachment. The results showed preferential colonisation of bacteria on the grain boundaries of the steel coupons. The bacterial attachment to AR steel coupons was relatively uniform compared to the HT steel coupons where an increased number of localised aggregates of bacteria were found. Quantitative analysis showed that the ratio of the total number of isolated (i.e., single) bacteria to the number of bacteria in aggregates was significantly higher on the AR coupons than the HT coupons. Longer-term immersion studies showed production of extracellular polymeric substances by the bacteria and corrosion at the grain boundaries on both types of steel coupon tested.

Development of a bioreactor for evaluating novel nerve conduits

Publisher: Wiley

Date: 10-10-2007

DOI: 10.1002/BIT.21669

Abstract: We describe an experimental closed bioreactor device for studying novel tissue engineered peripheral nerve conduits in vitro. The system integrates a closed loop system consisting of one, two, or three experimental nerve conduits connected in series or parallel, with the ability to study novel scaffolds within guidance conduits. The system was established using aligned synthetic microfiber scaffolds of viscose rayon and electrospun polystyrene. Schwann cells were seeded directly into conduits varying from 10 to 80 mm in length and allowed to adhere under 0 flow for 1 h, before being cultured for 4 days under static or continuous flow conditions. In situ viability measurements showed the distribution of live Schwann cells within each conduit and enabled quantification thereafter. Under static culture viable cells only existed in short conduit scaffolds (10 mm) or at the ends of longer conduits (20-80 mm) with a variation in viable cell distribution. Surface modification of scaffold fibers with type-1 collagen or acrylic acid increased cell number by 17% and 30%, respectively. However, a continuous medium flow of 0.8 mL/h was found to increase total cell number by 2.5-fold verses static culture. Importantly, under these conditions parallel viability measurements revealed a ninefold increase compared to static culture. Fluorescence microscopy of scaffolds showed cellular adhesion and alignment on the longitudinal axis. We suggest that such a system will enable a rigorous and controlled approach for evaluating novel conduits for peripheral nerve repair, in particular using hydrolysable materials for the parallel organization of nerve support cells, prior to in vivo study.

Optimal Translational Termination Requires C4 Lysyl Hydroxylation of eRF1

Publisher: Elsevier BV

Date: 02-2014

DOI: 10.1016/J.MOLCEL.2013.12.028

Multitechnique investigation into the aqueous behavior of plasma polymers

Publisher: American Vacuum Society

Date: 12-2018

DOI: 10.1116/1.5063750

Abstract: Plasma polymers are often used in applications requiring aqueous immersion therefore, it is important to understand how this exposure affects the physical and chemical properties of the films. Three different plasma polymer films were deposited at different distances from the electrode, and the film properties were characterized using contact angle, ellipsometry, and x-ray photoelectron spectroscopy. The film behaviors in aqueous solutions were studied via quartz crystal microbalance with dissipation (QCM-D). Exposure to buffer solutions produced significant swelling of the plasma polymerized acrylic acid films, with swelling increasing with distance from the powered electrode, results that could be correlated with changes in film chemistry. Plasma polymerized octadiene and allylamine exhibited little swelling. These films exhibited changes in thickness and contact angle with respect to distance from the electrode, but this had little influence on their behavior in aqueous solution. By combining QCM-D with the more traditional surface chemical analysis techniques, the authors have been able to explore both swelling behavior and the effect that s le position and thus deposition parameters have on film properties and aqueous behavior. This approach gives the authors the basis to define deposition parameters to assist the engineering of thin films for applications such as biosensing and tissue engineering applications where specific chemistries and film behaviors are desired.

Raman spectroscopic identification of single bacterial cells at different stages of their lifecycle

Publisher: Elsevier BV

Date: 09-2016

DOI: 10.1016/J.VIBSPEC.2016.06.008

Ultra-High Vacuum Surface Analysis Study of Rhodopsin Incorporation into Supported Lipid Bilayers

Publisher: American Chemical Society (ACS)

Date: 05-04-2008

DOI: 10.1021/LA800037R

Hybrid biomaterials: Surface-MALDI mass spectrometry analysis of covalent binding versus physisorption of proteins

Publisher: Elsevier BV

Date: 2000

DOI: 10.1016/S0927-7765(99)00055-7

Chemical and thermo-responsive characterisation of surfaces formed by plasma polymerisation ofN-isopropyl acrylamide

Publisher: Wiley

Date: 2006

DOI: 10.1002/SIA.2318

Ultrasonic separation of particulate fluids in small and large scale systems: A review

Publisher: American Chemical Society (ACS)

Date: 13-11-2013

DOI: 10.1021/IE402295R

Temperature effects on the ultrasonic separation of fat from natural whole milk

Publisher: Elsevier BV

Date: 11-2014

DOI: 10.1016/J.ULTSONCH.2014.02.003

Abstract: This study showed that temperature influences the rate of separation of fat from natural whole milk during application of ultrasonic standing waves. In this study, natural whole milk was sonicated at 600kHz (583W/L) or 1MHz (311W/L) with a starting bulk temperature of 5, 25, or 40°C. Comparisons on separation efficiency were performed with and without sonication. Sonication using 1MHz for 5min at 25°C was shown to be more effective for fat separation than the other conditions tested with and without ultrasound, resulting in a relative change from 3.5±0.06% (w/v) fat initially, of -52.3±2.3% (reduction to 1.6±0.07% (w/v) fat) in the skimmed milk layer and 184.8±33.2% (increase to 9.9±1.0% (w/v) fat) in the top layer, at an average skimming rate of ∼5g fat/min. A shift in the volume weighted mean diameter (D[4,3]) of the milk s les obtained from the top and bottom of between 8% and 10% relative to an initial s le D[4,3] value of 4.5±0.06μm was also achieved under these conditions. In general, faster fat separation was seen in natural milk when natural creaming occurred at room temperature and this separation trend was enhanced after the application of high frequency ultrasound.

Ultrasensitive probing of the protein resistance of PEG surfaces by secondary ion mass spectrometry

Publisher: Elsevier BV

Date: 12-2002

DOI: 10.1016/S0142-9612(02)00228-4

Abstract: The highly sensitive surface analytical techniques X-ray photoelectron spectroscopy (XPS) and time-of-flight static secondary ion mass spectrometry (ToF-SIMS) were used to test the resistance of poly(ethylene glycol) (PEG) coatings towards adsorption of lysozyme (LYS) and fibronectin (FN). PEG coatings were prepared by grafting methoxy-terminated aldehyde-PEG (MW 5000 Da) onto two amino-functionalised surfaces with different amine group densities, generated by radio frequency glow discharge polymerisation of n-heptylamine and allylamine. Grafting was performed at the lower critical solution temperature to maximise the graft density of the PEG chains. XPS showed that the grafted density of PEG chains was slightly higher on the allylamine surface. XPS detected no adsorption of either protein on either PEG coating. ToF-SIMS analysis, on the other hand, found, in the positive ion spectra, minute but statistically significant signals assignable to amino acid fragment ions from both proteins adsorbed to the lower density PEG coating and from LYS but not FN on the higher density PEG coating. Negative ion spectra contained relatively more intense protein fragment ion signals for the lower density PEG coating but no changes assignable to adsorbed proteins on the higher density PEG coating. These results demonstrate the importance of utilising highly sensitive techniques to study protein adsorption on surfaces intended to be protein resistant, and that both positive and negative ion ToF-SIMS spectra should be acquired to probe for possible very low levels of protein adsorption.

Ceric ammonium nitrate initiated grafting of PEG to plasma polymers for cell-resistant surfaces

Publisher: Wiley

Date: 05-02-2008

DOI: 10.1002/PPAP.200700062

Comparing the properties of commercially treated and air plasma treated carbon fibers

Publisher: Elsevier BV

Date: 02-2021

DOI: 10.1016/J.SURFCOAT.2020.126751

Electrospun Polystyrene Fiber Diameter Influencing Bacterial Attachment, Proliferation, and Growth

Publisher: American Chemical Society (ACS)

Date: 04-2015

DOI: 10.1021/ACSAMI.5B00453

Abstract: Electrospun materials have been widely investigated in the past few decades as candidates for tissue engineering applications. However, there is little available data on the mechanisms of interaction of bacteria with electrospun wound dressings of different morphology and surface chemistry. This knowledge could allow the development of effective devices against bacterial infections in chronic wounds. In this paper, the interactions of three bacterial species (Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus) with electrospun polystyrene meshes were investigated. Bacterial response to meshes with different fiber diameters was assessed through a combination of scanning electron microscopy (SEM) and confocal microscopy. Experiments included attachment studies in liquid medium but also directly onto agar plates the latter was aimed at mimicking a chronic wound environment. Fiber diameter was shown to affect the ability of bacteria to proliferate within the fibrous networks, depending on cell size and shape. The highest proliferation rates occurred when fiber diameter was close to the bacterial size. Nanofibers were found to induce conformational changes of rod shaped bacteria, limiting the colonization process and inducing cell death. The data suggest that simply tuning the morphological properties of electrospun fibers may be one strategy used to control biofilm formation within wound dressings.

Versatile SERS sensing based on black silicon

Publisher: The Optical Society

Date: 04-03-2015

DOI: 10.1364/OE.23.006763

Imaging approaches for monitoring three-dimensional cell and tissue culture systems.

Publisher: Wiley

Date: 24-04-2022

DOI: 10.1002/JBIO.202100380

Abstract: The past decade has seen an increasing demand for more complex, reproducible and physiologically relevant tissue cultures that can mimic the structural and biological features of living tissues. Monitoring the viability, development and responses of such tissues in real-time are challenging due to the complexities of cell culture physical characteristics and the environments in which these cultures need to be maintained in. Significant developments in optics, such as optical manipulation, improved detection and data analysis, have made optical imaging a preferred choice for many three-dimensional (3D) cell culture monitoring applications. The aim of this review is to discuss the challenges associated with imaging and monitoring 3D tissues and cell culture, and highlight topical label-free imaging tools that enable bioengineers and biophysicists to non-invasively characterise engineered living tissues.

Non-invasive bionic vision

Publisher: SPIE-Intl Soc Optical Eng

Date: 12-10-2011

DOI: 10.1117/2.1201109.003874

Characterization of fibrinogen adsorption onto glass microcapillary surfaces by ELISA

Publisher: Royal Society of Chemistry (RSC)

Date: 2007

DOI: 10.1039/B612521M

Abstract: Adsorption of biomolecules onto microchannel surfaces remains a critical issue in microfluidic devices. This paper investigates the adsorption of fibrinogen on glass microcapillaries using an immunoassay method (ELISA) and X-ray photoelectron spectroscopy (XPS). Various adsorption conditions such as protein concentrations and incubation times, buffer pH, buffer ionic strengths and effects of flow are presented. ELISA is successfully demonstrated as a facile and robust technique to examine these phenomena. The highest adsorption level occurs near the isoelectric point of fibrinogen (pH 5.0) and low buffer ionic strengths (0-8 mM). Microchannel surface saturation was achieved at a fibrinogen solution concentration of approximately 50 microg ml(-1). Fibrinogen adsorption under flow was always higher than that seen in static systems. The importance of diffusion phenomena in microchannels on protein adsorption was demonstrated. ELISA experiments using fused silica and PEEK have also confirmed significant adsorption on these mass spectrometer transfer line materials.

Spontaneously reactive plasma polymer micropatterns

Publisher: Elsevier BV

Date: 04-2011

DOI: 10.1016/J.POLYMER.2011.03.004

Limits of detection for time of flight secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS): detection of low amounts of adsorbed protein

Publisher: Informa UK Limited

Date: 2002

DOI: 10.1163/156856202320253938

Abstract: Characterization of biomaterial surfaces requires analytical techniques that are capable of detecting a wide concentration range of adsorbed protein. This range includes detection of low amounts of adsorbed protein (<10 ng/cm2) that may be present on non-fouling biomaterials. X-ray Photoelectron Spectroscopy (XPS) and Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) are surface sensitive techniques capable of detecting adsorbed proteins. We have investigated the lower limits of detection of both XPS and ToF-SIMS on four model substrates each presenting unique challenges for analysis by XPS and ToF-SIMS: mica, poly(tetrafluoroethylene), allyl amine plasma polymer and heptyl amine plasma polymer. The detection limit for XPS ranged from 10 ng/cm2 of fibrinogen (on mica) to 200 ng/cm2 (on allyl amine plasma polymers). The detection limit for ToF-SIMS ranged from 0.1 ng/cm2 of fibrinogen to 100 ng/cm2, depending on the substrate and data analysis. Optimal conditions provided detection limits between 0.1 ng/cm2 and 15 ng/cm2 on all of the substrates used in this study. While both techniques were shown to be effective in detecting protein, the sensitivity of both XPS and ToF-SIMS was shown to be dependent on substrate surface chemistry and the organization of the adsorbed protein film. This study specifically highlights the applicability of ToF-SIMS in the characterization of low level protein adsorption.

A NEXAFS examination of unsaturation in plasma polymers of allylamine and propylamine

Publisher: American Chemical Society (ACS)

Date: 22-07-2004

DOI: 10.1021/JP048250F

Label-free imaging of fibroblast membrane interfaces and protein signatures with vibrational infrared photothermal and phase signals.

Publisher: Optica Publishing Group

Date: 14-12-2020

DOI: 10.1364/BOE.411888

Abstract: Label-free vibrational imaging of biological s les has attracted significant interest due to its integration of structural and chemical information. Vibrational infrared photothermal litude and phase signal (VIPPS) imaging provide label-free chemical identification by targeting the characteristic resonances of biological compounds that are present in the mid-infrared fingerprint region (3 µm - 12 µm). High contrast imaging of subcellular features and chemical identification of protein secondary structures in unlabeled and labeled fibroblast cells embedded in a collagen-rich extracellular matrix is demonstrated by combining contrast from absorption signatures ( litude signals) with sensitive detection of different heat properties (lock-in phase signals). We present that the detectability of nano-sized cell membranes is enhanced to well below the optical diffraction limit since the membranes are found to act as thermal barriers. VIPPS offers a novel combination of chemical imaging and thermal diffusion characterization that paves the way towards label-free imaging of cell models and tissues as well as the study of intracellular heat dynamics.

Applications of XPS in biology and biointerface analysis

Publisher: Springer International Publishing

Date: 2014

DOI: 10.1007/978-3-319-01360-2_2

On the need for more realistic experimental conditions in laboratory-based microbiologically influenced corrosion testing

Publisher: Elsevier BV

Date: 07-2017

DOI: 10.1016/J.IBIOD.2017.03.027

Generation of Bioactive Materials with Rapid Self‐Assembling Resorcinarene‐Peptides

Publisher: Wiley

Date: 27-07-2009

DOI: 10.1002/ADMA.200802731

New developments at the biointerface

Publisher: American Vacuum Society

Date: 12-2015

DOI: 10.1116/1.4938024

‘Building up speed’, ‘trying to break free’, ‘pushing it through the pipe’: using metaphor to explore early career STEM researchers’ grant writing capability

Publisher: Informa UK Limited

Date: 06-12-2016

DOI: 10.1080/07294360.2016.1263833

Glycosaminoglycan (GAG) binding surfaces for characterizing GAG-protein interactions

Publisher: Elsevier BV

Date: 02-2012

DOI: 10.1016/J.BIOMATERIALS.2011.10.042

Abstract: Glycosaminoglycans play an important role in tissue organisation through interactions with a erse range of proteins, growth factors and other chemokines. In this report, we demonstrate the GAG-binding 'fingerprint' of two important GAG-binding proteins - osteoprotogerin and TIMP-3. The technique uses a straightforward method for attaching GAGs to assay surfaces in a non-covalent manner using plasma polymerization that leaves the adsorbed GAG able to participate in subsequent ligand binding. We show that OPG and TIMP-3 bind preferentially to different GAGs in a simple ELISA and that this binding does not correlate directly with simple GAG properties such as degree of sulfation. The methods outlined in this report can be easily applied to tissue engineering scaffolds in order to exploit the potential of surface-bound GAGs in influencing the structure of engineered tissues.

Cavitation and non-cavitation regime for large-scale ultrasonic standing wave particle separation systems - In situ gentle cavitation threshold determination and free radical related oxidation

Publisher: Elsevier BV

Date: 2016

DOI: 10.1016/J.ULTSONCH.2015.08.003

Abstract: We here suggest a novel and straightforward approach for liter-scale ultrasound particle manipulation standing wave systems to guide system design in terms of frequency and acoustic power for operating in either cavitation or non-cavitation regimes for ultrasound standing wave systems, using the sonochemiluminescent chemical luminol. We show that this method offers a simple way of in situ determination of the cavitation threshold for selected separation vessel geometry. Since the pressure field is system specific the cavitation threshold is system specific (for the threshold parameter range). In this study we discuss cavitation effects and also measure one implication of cavitation for the application of milk fat separation, the degree of milk fat lipid oxidation by headspace volatile measurements. For the evaluated vessel, 2 MHz as opposed to 1 MHz operation enabled operation in non-cavitation or low cavitation conditions as measured by the luminol intensity threshold method. In all cases the lipid oxidation derived volatiles were below the human sensory detection level. Ultrasound treatment did not significantly influence the oxidative changes in milk for either 1 MHz (dose of 46 kJ/L and 464 kJ/L) or 2 MHz (dose of 37 kJ/L and 373 kJ/L) operation.

Application of layer-by-layer coatings to tissue scaffolds-development of an angiogenic biomaterial

Publisher: Royal Society of Chemistry (RSC)

Date: 2014

DOI: 10.1039/C4TB00448E

Abstract: Development of flexible coating strategies to promote angiogenesis is critical to effectively treat chronic, non-healing wounds.

Effect of polysaccharide structure on protein adsorption

Publisher: Elsevier BV

Date: 2000

DOI: 10.1016/S0927-7765(99)00086-7

Polycaprolactone porous template facilitates modulated release of molecules from alginate hydrogels

Publisher: Elsevier BV

Date: 12-2018

DOI: 10.1016/J.REACTFUNCTPOLYM.2018.09.016

Continuous Flow Ultrasonic Skimming of Whole Milk in a Liter-Scale Vessel

Publisher: American Chemical Society (ACS)

Date: 08-12-2015

DOI: 10.1021/ACS.IECR.5B03142

Culture on fibrin matrices maintains the colony-forming capacity and osteoblastic differentiation of mesenchymal stem cells

Publisher: IOP Publishing

Date: 12-06-2012

DOI: 10.1088/1748-6041/7/4/045015

Abstract: Mesenchymal stem cells (MSC) are multipotent cells capable of differentiating into a number of mesenchymal tissues including bone, cartilage, and tendon. Low numbers in vivo means exponential growth is needed in culture to enable therapeutic applications. MSC can expand rapidly in culture but usually lose their extensive capacity for differentiation that makes them therapeutically attractive. To try and maintain their capacity for differentiation and expansion in vitro, we cultured MSC on fibrin gels of different concentrations to create more physiological growth conditions for the cells. The cells were then re-plated onto tissue culture plastic and analysed. The cells that had been pre-cultured for seven days on fibrin, proliferated and maintained their differential potential to the osteogenic lineage better than tissue culture plastic expanded MSC. A concentration relationship between colony number and fibrin concentration was seen with decreasing numbers as fibrin concentration increased. These data support the concept that substrate signals significantly influence MSC growth and differentiation and that growth on a fibrin matrix could be used to maintain a stem cell phenotype during MSC expansion.

Imaging the action of antimicrobial peptides on living bacterial cells

Publisher: Springer Science and Business Media LLC

Date: 27-03-2013

DOI: 10.1038/SREP01557

Time-of-Flight Secondary Ion Mass Spectrometry Analysis of Conformational Changes in Adsorbed Protein Films

Publisher: American Chemical Society (ACS)

Date: 19-04-2002

DOI: 10.1021/LA020022U

Extending In-Plane Impedance Measurements from 2D to 3D Cultures: Design Considerations

Publisher: MDPI AG

Date: 13-01-2021

DOI: 10.3390/BIOENGINEERING8010011

Abstract: Three-dimensional (3D) cell cultures have recently emerged as tools for biologically modelling the human body. As 3D models make their way into laboratories there is a need to develop characterisation techniques that are sensitive enough to monitor the cells in real time and without the need for chemical labels. Impedance spectroscopy has been shown to address both of these challenges, but there has been little research into the full impedance spectrum and how the different components of the system affect the impedance signal. Here we investigate the impedance of human fibroblast cells in 2D and 3D collagen gel cultures across a broad range of frequencies (10 Hz to 5 MHz) using a commercial well with in-plane electrodes. At low frequencies in both 2D and 3D models it was observed that protein adsorption influences the magnitude of the impedance for the cell-free s les. This effect was eliminated once cells were introduced to the systems. Cell proliferation could be monitored in 2D at intermediate frequencies (30 kHz). However, the in-plane electrodes were unable to detect any changes in the impedance at any frequency when the cells were cultured in the 3D collagen gel. The results suggest that in designing impedance measurement devices, both the nature and distribution of the cells within the 3D culture as well as the architecture of the electrodes are key variables.

Manufacture of Chemically Modified Antibacterial Surfaces

Publisher: Springer International Publishing

Date: 2015

DOI: 10.1007/978-3-319-18594-1_5

Inhibition or acceleration: Bacterial test media can determine the course of microbiologically influenced corrosion

Publisher: Elsevier BV

Date: 09-2014

DOI: 10.1016/J.CORSCI.2014.05.003

Arginine functionalization of hydrogels for heparin binding—a supramolecular approach to developing a pro‐angiogenic biomaterial

Publisher: Wiley

Date: 25-07-2012

DOI: 10.1002/BIT.24598

Abstract: Our aim was to synthesize a biomaterial that stimulates angiogenesis for tissue engineering applications by exploiting the ability of heparin to bind and release vascular endothelial growth factor (VEGF). The approach adopted involved modification of a hydrogel with positively charged peptides (oligolysine or oligoarginine) to achieve heparin binding. Precursor hydrogels were produced from copolymerization of N-vinyl pyrolidone, diethylene glycol bis allyl carbonate and acrylic acid (PNDA) and functionalized after activation of the carboxylic acid groups with trilysine or triarginine peptides (PNDKKK and PNDRRR). Both hydrogels were shown to bind and release bioactive VEGF165 with arginine-modified hydrogel outperforming the lysine-modified hydrogel. Cytocompatibility of the hydrogels was confirmed in vitro with primary human dermal fibroblasts and human dermal microvascular endothelial cells (HUDMECs). Proliferation of HUDMECs was stimulated by triarginine-functionalized hydrogels, and to a lesser extent by lysine functionalized hydrogels once loaded with heparin and VEGF. The data suggests that heparin-binding hydrogels provide a promising approach to a pro-angiogenic biomaterial.

Practical guides for x-ray photoelectron spectroscopy: Analysis of polymers

Publisher: American Vacuum Society

Date: 12-02-2020

DOI: 10.1116/1.5140587

Abstract: XPS is widely used to identify and quantify the elements present at the surface of polymeric materials. The energy distribution of photoelectrons emitted from these elements contains information about their chemical state, potentially allowing the analyst to identify and quantify specific functional groups. These functional groups may originate from the synthesis and processing of the polymers, from postsynthetic modifications such as surface grafting, or indeed may be unrelated to the polymer (additives and contaminants). Extracting reliable and meaningful information from XPS data is not trivial and relies on careful and appropriate experimentation, including experimental design, s le preparation, data collection, data processing, and data interpretation. Here, the authors outline some of these challenges when performing XPS analysis of polymers and provide practical ex les to follow. This guide will cover all relevant aspects over the course of a typical experiment, including tips and considerations when designing the experiment, s le preparation, charge neutralization, x-ray induced s le damage, depth profiling, data analysis and interpretation, and, finally, reporting of results. Many of these topics are more widely applicable to insulating organic materials, and the recommendations of this guide will help to ensure that data is collected and interpreted using current best practices.

Design and characterization of a plasma chamber for improved radial and axial film uniformity

Publisher: Wiley

Date: 25-03-2020

DOI: 10.1002/PPAP.202000017

Chitosan-coated amyloid fibrils increase adipogenesis of mesenchymal stem cells

Publisher: Elsevier BV

Date: 10-2017

DOI: 10.1016/J.MSEC.2017.05.050

Abstract: Mesenchymal stem cells (MSCs) have the potential to revolutionize medicine due to their ability to differentiate into specific lineages for targeted tissue repair. Development of materials and cell culture platforms that improve differentiation of either autologous or allogenic stem cell sources into specific lineages would enhance clinical utilization of MCSs. In this study, nanoscale amyloid fibrils were evaluated as substrate materials to encourage viability, proliferation, multipotency, and differentiation of MSCs. Fibrils assembled from the proteins lysozyme or β-lactoglobulin, with and without chitosan coatings, were deposited on planar mica surfaces. MSCs were cultured and differentiated on fibril-covered surfaces, as well as on unstructured controls and tissue culture plastic. Expression of CD44 and CD90 proteins indicated that multipotency was maintained for all fibrils, and osteogenic differentiation was similarly comparable among all tested materials. MSCs grown for 7days on fibril-covered surfaces favored multicellular spheroid formation and demonstrated a >75% increase in adipogenesis compared to tissue culture plastic controls, although this benefit could only be achieved if MSCs were transferred to TCP for the final differentiation step. The largest spheroids and greatest tendency to undergo adipogenesis was evidenced among MSCs grown on fibrils coated with the positively-charged polysaccharide chitosan, suggesting that spheroid formation is prompted by both topography and cell-surface interactivity and that there is a connection between multicellular spheroid formation and adipogenesis.

Improved methods for fluorescence background subtraction from Raman spectra

Publisher: Wiley

Date: 02-09-2013

DOI: 10.1002/JRS.4371

Synthesis and characterization of immobilized PAMAM dendrons

Publisher: Royal Society of Chemistry (RSC)

Date: 2007

DOI: 10.1039/B701550J

Abstract: This communication describes the synthesis and characterization of immobilized PAMAM dendrons onto a surface modified silicon wafer substrate (functionalized using plasma polymerized PAA) using a "growing from" strategy.

Design parameters for the separation of fat from natural whole milk in an ultrasonic litre-scale vessel

Publisher: Elsevier BV

Date: 07-2014

DOI: 10.1016/J.ULTSONCH.2014.01.007

Abstract: The separation of milk fat from natural whole milk has been achieved by applying ultrasonic standing waves (1 MHz and/or 2 MHz) in a litre-scale (5L capacity) batch system. Various design parameters were tested such as power input level, process time, specific energy, transducer-reflector distance and the use of single and dual transducer set-ups. It was found that the efficacy of the treatment depended on the specific energy density input into the system. In this case, a plateau in fat concentration of ∼20% w/v was achieved in the creamed top layer after applying a minimum specific energy of 200 kJ/kg. In addition, the fat separation was enhanced by reducing the transducer reflector distance in the vessel, operating two transducers in a parallel set-up, or by increasing the duration of insonation, resulting in skimmed milk with a fat concentration as low as 1.7% (w/v) using raw milk after 20 min insonation. Dual mode operation with both transducers in parallel as close as 30 mm apart resulted in the fastest creaming and skimming in this study at ∼1.6 g fat/min.

Antibacterial activity studies of plasma polymerised cineole films

Publisher: Royal Society of Chemistry (RSC)

Date: 2014

DOI: 10.1039/C4TB00633J

Abstract: Costs associated with bacterial infections in medical devices exceed $US 30 billion each year in the United States alone due to device revisions and patient treatment.

Stable low-fouling plasma polymer coatings on polydimethylsiloxane

Publisher: AIP Publishing

Date: 09-2012

DOI: 10.1063/1.4754600

Abstract: Polydimethylsiloxane (DMS) is a popular material for microfluidics, but it is hydrophobic and is prone to non-specific protein adsorption. In this study, we explore methods for producing stable, protein resistant, tetraglyme plasma polymer coatings on PDMS by combining extended baking processes with multiple plasma polymer coating steps. We demonstrate that by using this approach, it is possible to produce a plasma polymer coatings that resist protein adsorption (& ng/cm2) and are stable to storage over at least 100 days. This methodology can translate to any plasma polymer system, enabling the introduction of a wide range of surface functionalities on PDMS surfaces.

In Focus: Women in biointerface science.

Publisher: American Vacuum Society

Date: 12-2018

DOI: 10.1116/1.5082176

Fabrication of a platform to isolate the influences of surface nanotopography from chemistry on bacterial attachment and growth

Publisher: American Vacuum Society

Date: 26-02-2015

DOI: 10.1116/1.4913377

Abstract: Billions of dollars are spent annually worldwide to combat the adverse effects of bacterial attachment and biofilm formation in industries as varied as maritime, food, and health. While advances in the fabrication of antifouling surfaces have been reported recently, a number of the essential aspects responsible for the formation of biofilms remain unresolved, including the important initial stages of bacterial attachment to a substrate surface. The reduction of bacterial attachment to surfaces is a key concept in the prevention or minimization of biofilm formation. The chemical and physical characteristics of both the substrate and bacteria are important in understanding the attachment process, but substrate modification is likely the most practical route to enable the extent of bacterial attachment taking place to be effectively controlled. The microtopography and chemistry of the surface are known to influence bacterial attachment. The role of surface chemistry versus nanotopography and their interplay, however, remain unclear. Most methods used for imparting nanotopographical patterns onto a surface also induce changes in the surface chemistry and vice versa. In this study, the authors combine colloidal lithography and plasma polymerization to fabricate homogeneous, reproducible, and periodic nanotopographies with a controllable surface chemistry. The attachment of Escherichia coli bacteria onto carboxyl (plasma polymerized acrylic acid, ppAAc) and hydrocarbon (plasma polymerized octadiene, ppOct) rich plasma polymer films on either flat or colloidal array surfaces revealed that the surface chemistry plays a critical role in bacterial attachment, whereas the effect of surface nanotopography on the bacterial attachment appears to be more difficult to define. This platform represents a promising approach to allow a greater understanding of the role that surface chemistry and nanotopography play on bacterial attachment and the subsequent biofouling of the surface.

Toward a quantified, validated, and verifiable understanding of the Biointerface

Publisher: American Vacuum Society

Date: 12-2016

DOI: 10.1116/1.4972550

Ultrasonically enhanced fractionation of milk fat in a litre-scale prototype vessel

Publisher: Elsevier BV

Date: 2016

DOI: 10.1016/J.ULTSONCH.2015.06.023

Abstract: The ultrasonic fractionation of milk fat in whole milk to fractions with distinct particle size distributions was demonstrated using a stage-based ultrasound-enhanced gravity separation protocol. Firstly, a single stage ultrasound gravity separation was characterised after various sonication durations (5-20 min) with a mass balance, where defined volume partitions were removed across the height of the separation vessel to determine the fat content and size distribution of fat droplets. Subsequent trials using ultrasound-enhanced gravity separation were carried out in three consecutive stages. Each stage consisted of 5 min sonication, with single and dual transducer configurations at 1 MHz and 2 MHz, followed by aliquot collection for particle size characterisation of the formed layers located at the bottom and top of the vessel. After each sonication stage, gentle removal of the separated fat layer located at the top was performed. Results indicated that ultrasound promoted the formation of a gradient of vertically increasing fat concentration and particle size across the height of the separation vessel, which became more pronounced with extended sonication time. Ultrasound-enhanced fractionation provided fat enriched fractions located at the top of the vessel of up to 13 ± 1% (w/v) with larger globules present in the particle size distributions. In contrast, semi-skim milk fractions located at the bottom of the vessel as low as 1.2 ± 0.01% (w/v) could be produced, containing proportionally smaller sized fat globules. Particle size differentiation was enhanced at higher ultrasound energy input (up to 347 W/L). In particular, dual transducer after three-stage operation at maximum energy input provided highest mean particle size differentiation with up to 0.9 μm reduction in the semi-skim fractions. Higher frequency ultrasound at 2 MHz was more effective in manipulating smaller sized fat globules retained in the later stages of skimming than 1 MHz. While 2 MHz ultrasound removed 59 ± 2% of the fat contained in the initial s le, only 47 ± 2% was removed with 1 MHz after 3 ultrasound-assisted fractionation stages.

In situ monitoring of the effect of ionic strength and pH on plasma polymer thin films

Publisher: Wiley

Date: 24-05-2017

DOI: 10.1002/PPAP.201700084

Plasma Polymer Coatings to Support Mesenchymal Stem Cell Adhesion, Growth and Differentiation on Variable Stiffness Silicone Elastomers

Publisher: Wiley

Date: 04-12-2009

DOI: 10.1002/PPAP.200900040

A ToF-SSIMS study of plasma polymer-based patterned metal affinity surfaces

Publisher: Elsevier BV

Date: 10-2009

DOI: 10.1016/J.POLYMER.2009.09.005

Plasma Polymerization of Maleic Anhydride: Just What Are the Right Deposition Conditions?

Publisher: American Chemical Society (ACS)

Date: 05-05-2010

DOI: 10.1021/LA100236C

Temperature measurement in the microscopic regime: a comparison between fluorescence lifetime‐ and intensity‐based methods

Publisher: Wiley

Date: 22-03-2013

DOI: 10.1111/JMI.12033

Abstract: Thermally sensitive fluorescent indicators have been proposed to monitor temperature changes in microfluidic systems, mainly based on fluorescence intensity or lifetime. However, measuring temperature in a structured environment, such as biological tissue, presents additional challenges due to the chemical and structural complexity. Here, we investigate the potential for resolving temperature distributions within the volume of a single cell. Rhodamine B (RhB) dye was employed as a temperature indicator to compare fluorescence intensity- and lifetime-based techniques. The relationship between the fluorescence lifetime and temperature was found to be highly dependent on the biological environment. The intensity-based method allowed the temperature distribution to be mapped with partial success within the volume of a single cell. Under ideal circumstances, the temperature can be mapped pixel by pixel with a resolution better than ±0.3°C within the cell cytoplasm, but this accuracy was reduced to ±1.8°C by environmental variations. These results suggest that the fluorophore should be encapsulated and immobilized in the biological tissue in order to reduce the influence of environmental factors on temperature measurements at the cellular level.

Repeatability, Reproducibility, and Replicability: Tackling the 3R challenge in biointerface science and engineering

Publisher: American Vacuum Society

Date: 03-2019

DOI: 10.1116/1.5093621

Journals as communities of practice

Publisher: American Vacuum Society

Date: 05-2020

DOI: 10.1116/6.0000348

Three-Dimensional (3D) cell culture monitoring: Opportunities and challenges for impedance spectroscopy.

Publisher: Wiley

Date: 03-02-2020

DOI: 10.1002/BIT.27270

Abstract: Three-dimensional (3D) cell culture has developed rapidly over the past 5-10 years with the goal of better replicating human physiology and tissue complexity in the laboratory. Quantifying cellular responses is fundamental in understanding how cells and tissues respond during their growth cycle and in response to external stimuli. There is a need to develop and validate tools that can give insight into cell number, viability, and distribution in real-time, nondestructively and without the use of stains or other labelling processes. Impedance spectroscopy can address all of these challenges and is currently used both commercially and in academic laboratories to measure cellular processes in 2D cell culture systems. However, its use in 3D cultures is not straight forward due to the complexity of the electrical circuit model of 3D tissues. In addition, there are challenges in the design and integration of electrodes within 3D cell culture systems. Researchers have used a range of strategies to implement impedance spectroscopy in 3D systems. This review examines electrode design, integration, and outcomes of a range of impedance spectroscopy studies and multiparametric systems relevant to 3D cell cultures. While these systems provide whole culture data, impedance tomography approaches have shown how this technique can be used to achieve spatial resolution. This review demonstrates how impedance spectroscopy and tomography can be used to provide real-time sensing in 3D cell cultures, but challenges remain in integrating electrodes without affecting cell culture functionality. If these challenges can be addressed and more realistic electrical models for 3D tissues developed, the implementation of impedance-based systems will be able to provide real-time, quantitative tracking of 3D cell culture systems.

Methods for Generating Protein Molecular Ions in ToF-SIMS

Publisher: American Chemical Society (ACS)

Date: 23-03-2004

DOI: 10.1021/LA0358419

Abstract: One of the greatest challenges in mass spectrometry lies in the generation and detection of molecular ions that can be used to directly identify the protein from the molecular weight of the molecular ion. Typically, proteins are large (MW > 1000), nonvolatile, and/or thermally labile, but the vaporization process produced by many mass spectrometry techniques including time-of-flight secondary ion mass spectrometry (ToF-SIMS) is inherently limited to generating ions from smaller compounds or fragments of the parent molecule, making the identification of proteins complex. The application of specific molecules to aid in the generation of high molecular weight ions in ToF-SIMS has been recognized for some time. In this study we have developed a matrix-SAM substrate preparation technique based on the self-assembly of a matrix-like molecule, mercaptonicotinic acid (MNA), on gold. We then compare this substrate with two existing ToF-SIMS s le preparation techniques, cationized alkane thiol and matrix-enhanced SIMS (MESIMS). The results of this study illustrate that while there is a range of methods that can be used to improve the molecular ion yield of proteins in ToF-SIMS, their efficacy and reproducibility vary considerably and crucially are linked to the s le preparation and/or protein application methods used. Critically, the MNA modified substrate was able to simultaneously induce molecular ions for each protein present in a multicomponent solution, suggesting that this s le preparation technique may have future application in proteomics and DNA analysis.

Applications of XPS in bioengineering

Publisher: Wiley

Date: 18-10-2006

DOI: 10.1002/SIA.2498

Physicochemical properties of polysaccharide coatings based on grafted multilayer assemblies

Publisher: American Chemical Society (ACS)

Date: 23-02-2002

DOI: 10.1021/LA001801I

Gold-Nanorod-Assisted Near-Infrared Stimulation of Primary Auditory Neurons

Publisher: Wiley

Date: 05-05-2014

DOI: 10.1002/ADHM.201400027

Abstract: Infrared stimulation offers an alternative to electrical stimulation of neuronal tissue, with potential for direct, non-contact activation at high spatial resolution. Conventional methods of infrared neural stimulation (INS) rely on transient heating due to the absorption of relatively intense laser beams by water in the tissue. However, the water absorption also limits the depth of penetration of light in tissue. Therefore, the use of a near-infrared laser at 780 nm to stimulate cultured rat primary auditory neurons that are incubated with silica-coated gold nanorods (Au NRs) as an extrinsic absorber is investigated. The laser-induced electrical behavior of the neurons is observed using whole-cell patch cl electrophysiology. The nanorod-treated auditory neurons (NR-ANs) show a significant increase in electrical activity compared with neurons that are incubated with non-absorbing silica-coated gold nanospheres and control neurons with no gold nanoparticles. The laser-induced heating by the nanorods is confirmed by measuring the transient temperature increase near the surface of the NR-ANs with an open pipette electrode. These findings demonstrate the potential to improve the efficiency and increase the penetration depth of INS by labeling nerves with Au NRs and then exposing them to infrared wavelengths in the water window of tissue.

Editorial: In Focus Issue on Bacterial-Surface Interactions

Publisher: American Vacuum Society

Date: 12-2017

DOI: 10.1116/1.5017990

Characterization of sequentially grafted polysaccharide coating using time of flight secondary ion mass spectrometry (ToF-SIMS) and principal component analysis (PCA)

Publisher: Wiley

Date: 2002

DOI: 10.1002/SIA.1446

Gold Nanorod-assisted Optical Stimulation of Neuronal Cells

Publisher: MyJove Corporation

Date: 27-04-2015

DOI: 10.3791/52566

Physical vs Photolithographic Patterning of Plasma Polymers: An Investigation by ToF-SSIMS and Multivariate Analysis

Publisher: American Chemical Society (ACS)

Date: 12-2010

DOI: 10.1021/LA902930Z

Three-Dimensional Alignment of Schwann Cells Using Hydrolysable Microfiber Scaffolds: Strategies for Peripheral Nerve Repair

Publisher: Humana Press

Date: 07-10-2010

DOI: 10.1007/978-1-60761-984-0_10

Abstract: Injuries to the peripheral nervous system affect 1 in 1,000 in iduals each year. The implication of sustaining such an injury is considerable with loss of sensory and/or motor function. The economic implications too are extensive running into millions of pounds (or dollars) annually for provision and support. The natural regrowth of peripheral nerves is possible for small gap injuries (of approximately 1-2 mm). However, patients with larger gap injuries require surgical intervention. The "gold standard" for repairing gap injuries is autografting however, there are problems associated with this approach, and so, the use of nerve guidance conduits (NGC) is a realistic alternative. We outline in this chapter the development of an NGC that incorporates aligned poly-L-lactide fibres for supporting the growth of organised Schwann cells within a three-dimensional scaffold in vitro. A closed loop bioreactor for growing cells within NGC scaffolds is described together with a method of plasma deposition for modifying the microfibre surface chemistry (which improves the ability of Schwann cells to attach) and confocal microscopy for measuring cell viability and alignment within 3D constructs.

Laser exposure of gold nanorods can induce intracellular calcium transients

Publisher: Wiley

Date: 25-06-2013

DOI: 10.1002/JBIO.201300043

Abstract: Uncoated and poly(styrene sulphonate) (PSS)-coated gold nanorods were taken up by NG108-15 neuronal cells. Exposure to 780 nm laser light at the plasmon resonance wavelength of the gold nanorods was found to induce intracellular Ca(2+) transients. The higher Ca(2+) peaks were observed at lower laser doses, with the highest levels obtained at a radiant exposure of 0.33 J/cm(2) . In contrast, the cells without nanoparticles showed a consistently small response, independent of the laser dose. These initial results open up new opportunities for peripheral nerve regeneration treatments and for more efficient optical stimulation techniques.

Toward Immunocompetent 3D Skin Models

Publisher: Wiley

Date: 15-03-2018

DOI: 10.1002/ADHM.201701405

Abstract: 3D human skin models provide a platform for toxicity testing, biomaterials evaluation, and investigation of fundamental biological processes. However, the majority of current in vitro models lack an inflammatory system, vasculature, and other characteristics of native skin, indicating scope for more physiologically complex models. Looking at the immune system, there are a variety of cells that could be integrated to create novel skin models, but to do this effectively it is also necessary to understand the interface between skin biology and tissue engineering as well as the different roles the immune system plays in specific health and disease states. Here, a progress report on skin immunity and current immunocompetent skin models with a focus on construction methods is presented scaffold and cell choice as well as the requirements of physiologically relevant models are elaborated. The wide range of technological and fundamental challenges that need to be addressed to successfully generate immunocompetent skin models and the steps currently being made globally by researchers as they develop new models are explored. Induced pluripotent stem cells, microfluidic platforms to control the model environment, and new real-time monitoring techniques capable of probing biochemical processes within the models are discussed.

Electron Beam Lithography Nanopatterning of Plasma Polymers

Publisher: Wiley

Date: 05-03-2021

DOI: 10.1002/MACP.202100026

Abstract: Chemically patterned surfaces for biotechnology applications often require sub‐micron patterns to match specific sub‐cellular structures and control the presentation of proteins to single cell arrays. Plasma polymer coatings are used extensively in the biotechnology sector for biomaterials, cell culture and tissue engineering, but their patterning has not been investigated at the sub‐micron level. The resolution limit of plasma polymerized patterns with designed line widths of 900 to 20 nm is investigated via dual chemistry patterns of plasma polymerized acrylic acid and allylamine created with poly (methyl methacrylate) resist and electron beam lithography (EBL). Line widths are characterized via scanning electron microscopy and atomic force microscopy with surface chemistry analysis via time‐of‐flight secondary‐ion mass spectrometry (ToF‐SIMS). The smallest line width measured is 29 nm for a designed line width of 20 nm. High‐resolution nanoscale imaging is achieved using ToF‐SIMS, with lines down to ≈60 nm in width visible. This work demonstrates the successful fabrication and characterization of sub 100 nm dual plasma polymer patterns using EBL, establishing a clear route for large scale production of plasma polymerized nanopatterning.

Interfacial properties and protein resistance of nano-scale polysaccharide coatings

Publisher: IOP Publishing

Date: 13-09-2002

DOI: 10.1088/0964-1726/11/5/305

Surface modification and chemical surface analysis of biomaterials

Publisher: Elsevier BV

Date: 10-2011

DOI: 10.1016/J.CBPA.2011.07.012

Abstract: The chemical composition of the surface layers of synthetic biomaterials used for human medical devices and in biotechnology plays a key role in determining interfacial interactions between biological media (such as protein solutions, cells, tissue) and the synthetic material. Accordingly, considerable research efforts focus on improving the 'biocompatibility' of biomaterials by applying various surface modification and thin film coating approaches. Here we focus on the patterning of surface chemistries, often designed to exercise spatial control over events such as cell attachment and spreading. Secondly, we review recent developments in chemical characterisation of biomaterials surfaces, which is essential both for verifying the success of intended surface modification strategies and for reliable interpretation of observed biological responses. Biomaterials surface analysis by imaging ToF-SIMS and XPS and compositional depth profiling are discussed, as is the emerging complementary technique of Metastable Induced Electron Spectroscopy.

Dark-field microspectroscopic analysis of gold nanorods in spiral Ganglion neurons

Publisher: SPIE

Date: 07-12-2013

DOI: 10.1117/12.2033767

Laser exposure of gold nanorods can increase neuronal cell outgrowth

Publisher: Wiley

Date: 26-03-2013

DOI: 10.1002/BIT.24889

Abstract: The usage of gold nanoparticles (Au NPs) in biological applications has risen significantly over the last 10 years. With the wide variety of chemical and biological functionalization available and their distinctive optical properties, Au NPs are currently used in a range of biological applications including sensing, labeling, drug delivery, and imaging applications. Among the available particles, gold nanorods (Au NRs) are particularly useful because their optical absorption can be tuned across the visible to near infrared region. Here, we present a novel application of Au NRs associated with low power laser exposure of NG108-15 neuronal cells. When cells were irradiated with a 780 nm laser, the average number of neurons with neurites increased. A similar stimulatory effect was observed for cells that were cultured with poly-(4-styrenesulfonic acid)-coated and silica-coated Au NRs. Furthermore, when the NG108-15 cells were cultured with both bare and coated Au NRs and then irradiated with 1.2-7.5 W/cm(2) at 780 nm, they showed a neurite length increase of up to 25 µm versus control. To the best of our knowledge, this effect has never been reported before. While the pathways of the stimulation is not yet clear, the data presented here demonstrates that it is linked to the absorption of light by the Au NRs. These initial results open up new opportunities for peripheral nerve regeneration treatments and for novel approaches to addressing central nervous system axons following spinal cord injury.

Studies of electroosmotic flow and the effects of protein adsorption in plasma‐polymerized microchannel surfaces

Publisher: Wiley

Date: 06-2009

DOI: 10.1002/ELPS.200800619

Abstract: This paper presents a study of EOF properties of plasma-polymerized microchannel surfaces and the effects of protein (fibrinogen and lysozyme) adsorption on the EOF behavior of the surface-modified microchannels. Three plasma polymer surfaces, i.e. tetraglyme, acrylic acid and allylamine, are tested. Results indicate EOF suppression in all plasma-coated channels compared with the uncoated glass microchannel surfaces. The EOF behaviors of the modified microchannels after exposure to protein solutions are also investigated and show that even low levels of protein adsorption can significantly influence EOF behavior, and in some cases, result in the reversal of flow. The results also highlight that EOF measurement can be used as a method for detecting the presence of proteins within microchannels at low surface coverage (<1 ng/cm(2) on glass). Critically, the results illustrate that the non-fouling tetraglyme plasma polymer is able to sustain EOF. Comparison of the plasma-polymerized surfaces with conventionally grafted polyelectrolyte surfaces demonstrates the stabilities of the plasma polymer films, enabling multiple EOF runs over 3 days without deterioration in performance. The results of this study clearly demonstrate that plasma polymers enable the surface chemistry of microfluidic devices to be tailored for specific applications. Critically, the deposition of the non-fouling tetraglyme coating enables stable EOF to be induced in the presence of protein.

Applying click chemistry to polyurethanes: A straightforward approach for glycopolymer synthesis

Publisher: Royal Society of Chemistry (RSC)

Date: 2011

DOI: 10.1039/C1PY00412C

Fabrication and characterization of nanoscale biological coatings on synthetic carriers

Publisher: SPIE

Date: 19-11-2001

DOI: 10.1117/12.454587

Characterising a Custom-Built Radio Frequency PECVD Reactor to Vary the Mechanical Properties of TMDSO Films

Publisher: MDPI AG

Date: 16-09-2021

DOI: 10.3390/MOLECULES26185621

Abstract: Plasma-polymerised tetramethyldisiloxane (TMDSO) films are frequently applied as coatings for their abrasion resistance and barrier properties. By manipulating the deposition parameters, the chemical structure and thus mechanical properties of the films can also be controlled. These mechanical properties make them attractive as energy adsorbing layers for a range of applications, including carbon fibre composites. In this study, a new radio frequency (RF) plasma-enhanced chemical vapour deposition (PECVD) plasma reactor was designed with the capability to coat fibres with an energy adsorbing film. A key characterisation step for the system was establishing how the properties of the TMDSO films could be modified and compared with those deposited using a well-characterized microwave (MW) PECVD reactor. Film thickness and chemistry were determined with ellipsometry and X-ray photoelectron spectroscopy, respectively. The mechanical properties were investigated by nanoindentation and atomic force microscopy with peak-force quantitative nanomechanical mapping. The RF PECVD films had a greater range of Young’s modulus and hardness values than the MW PECVD films, with values as high as 56.4 GPa and 7.5 GPa, respectively. These results demonstrated the varied properties of TMDSO films that could in turn be deposited onto carbon fibres using a custom-built RF PECVD reactor.

Non-fouling microfluidic chip produced by radio frequency tetraglyme plasma deposition

Publisher: Royal Society of Chemistry (RSC)

Date: 2007

DOI: 10.1039/B615328C

Abstract: This Technical Note presents the direct surface modification of a glass/PTFE hybrid microfluidic chip, via radio frequency glow discharge plasma polymerisation of tetraethlylene glycol dimethylether (tetraglyme), to produce hydrophilic, non-fouling, PEO-like surfaces. We use several techniques including X-ray photoelectron spectroscopy (XPS), direct enzyme-linked immunosorbent assays (ELISA) and immunofluorescent imaging to investigate the channel coatings. Our results indicate the successful deposition of a PEO-like coating onto microchannel surfaces that has both solution and shelf stability (>3 months) and is capable of preventing fibrinogen adsorption to the microchannel surfaces.

Surface-MALDI mass spectrometry in biomaterials research

Publisher: Elsevier BV

Date: 09-2004

DOI: 10.1016/J.BIOMATERIALS.2004.01.049

Plasmonic properties of gold nanoparticles can promote neuronal activity

Publisher: SPIE

Date: 15-02-2013

DOI: 10.1117/12.2002291

CSIRO

Location: Australia

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Commonwealth Scientific And Industrial Research Organisation

Location: Australia

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Swinburne University Of Technology

Location: Australia

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Institute For Frontier Materials, Deakin University

Location: Australia

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Institute For Frontier Materials, Deakin University

Location: No location found

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Linkage Infrastructure, Equipment And Facilities - Grant ID: LE100100215

Start Date: 2010

End Date: 12-2010

Amount: $350,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP110200499

Start Date: 07-2011

End Date: 09-2016

Amount: $300,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP110103032

Start Date: 07-2011

End Date: 12-2016

Amount: $340,000.00

Funder: Australian Research Council

Industrial Transformation Training Centres - Grant ID: IC140100023

Start Date: 04-2015

End Date: 06-2019

Amount: $1,800,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE140100104

Start Date: 2014

End Date: 12-2014

Amount: $500,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE220100114

Start Date: 07-2022

End Date: 12-2023

Amount: $1,040,375.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP140100165

Start Date: 05-2014

End Date: 06-2018

Amount: $390,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE140100090

Start Date: 04-2014

End Date: 12-2016

Amount: $200,000.00

Funder: Australian Research Council

Industrial Transformation Training Centres - Grant ID: IC200100001

Start Date: 08-2021

End Date: 08-2026

Amount: $4,879,415.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE120100021

Start Date: 01-2012

End Date: 12-2013

Amount: $150,000.00

Funder: Australian Research Council