ORCID Profile
0000-0003-2250-8334
Current Organisation
La Trobe University
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In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Functional Materials | Biomaterials | Cellular Interactions (incl. Adhesion, Matrix, Cell Wall) | Physical Chemistry of Materials | Medical Devices | Biochemistry and Cell Biology | Biomedical Engineering | Materials Engineering | Composite and Hybrid Materials |
Expanding Knowledge in Engineering | Energy Storage (excl. Hydrogen) | Solar-Photovoltaic Energy | Expanding Knowledge in the Chemical Sciences | Nervous System and Disorders | Expanding Knowledge in the Biological Sciences | Hearing, Vision, Speech and Their Disorders | Expanding Knowledge in Technology
Publisher: Wiley
Date: 21-07-2017
Abstract: Organic ionic plastic crystals (OIPCs) are a class of solid-state electrolytes with good thermal stability, non-flammability, non-volatility, and good electrochemical stability. When prepared in a composite with electrospun polyvinylidene fluoride (PVdF) nanofibers, a 1:1 mixture of the OIPC N-ethyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide ([C
Publisher: Elsevier BV
Date: 06-2015
DOI: 10.1016/J.BIOMATERIALS.2015.02.086
Abstract: Lubricin is a glycoprotein found in articular joints which has been recognized as being an important biological boundary lubricant molecule. Besides providing lubrication, we demonstrate, using a quartz crystal microbalance, that lubricin also exhibits anti-adhesive properties and is highly effective at preventing the non-specific adsorption of representative globular proteins and constituents of blood plasma. This impressive anti-adhesive property, combined with lubricin's ability to readily self-assemble to form dense, highly stable telechelic polymer brush layers on virtually any substrates, and its innate biocompatibility, makes it an attractive candidate for anti-adhesive and anti-fouling coatings. We show that coatings of lubricin protein are as effective as, or better than, self-assembled monolayers of polyethylene glycol over a wide range of pH and that this provides a simple, versatile, highly stable, and highly effective method of controlling unwanted adhesion to surfaces.
Publisher: American Chemical Society (ACS)
Date: 06-12-2016
DOI: 10.1021/ACS.LANGMUIR.6B03467
Abstract: Adhesive interactions between nanofibers strongly influence the mechanical behavior of soft materials composed of fibrous networks. We use atomic force microscopy in lateral force mode to drag a cantilever tip through fibrous networks, and use the measured lateral force response to determine the adhesive forces between fibers of the order of 100 nm diameter. The peaks in lateral force curves are directly related to the detachment energy between two fibers the data is analyzed using the Jarzynski equality to yield the average adhesion energy of the weakest links. The method is successfully used to measure adhesion forces arising from van der Waals interactions between electrospun polymer fibers in networks of varying density. This approach overcomes the need to isolate and handle in idual fibers, and can be readily employed in the design and evaluation of advanced materials and biomaterials which, through inspiration from nature, are increasingly incorporating nanofibers. The data obtained with this technique may also be of critical importance in the development of network models capable of predicting the mechanics of fibrous materials.
Publisher: Elsevier BV
Date: 11-2008
DOI: 10.1016/J.BIOMATERIALS.2008.07.046
Abstract: Cartilage sections were cut from the middle zone of pig knee articular cartilage and attached to substrates in two different kinds of newly designed 'pressure cells', one for fluorescence the other for NMR measurements. The fluorescence cell was filled with buffer solution containing fluorescently marked 70 kDa dextran which was allowed to diffuse into the cartilage pores. A second glass surface was then pressed down onto the thin cartilage s le under different loads (pressures), and the resulting compression (strain) and change in pore volume were measured as a function of time, simultaneously with measurements of the lateral diffusion and flow pattern of the dextran molecules using Fluorescence Recovery After Photobleaching (FRAP). Complementary experiments were made on the normal diffusion coefficients of pure electrolyte solutions (no dextran) in thicker cartilage sections with pulse-gradient NMR using a new pressure cell suitable for such measurements. Taken together our results show that the highly anisotropic structure of cartilage has a strong effect on the way fluid diffuses laterally and normally at different stages of compression. Our results also show how geometric constraints on a cartilage network and trapped high MW polymer such as HA during normal compressions are likely to affect both the normal and the lateral mobilities of polyelectrolytes and water.
Publisher: Wiley
Date: 15-03-2019
Publisher: American Chemical Society (ACS)
Date: 05-02-2016
DOI: 10.1021/ACS.LANGMUIR.5B03535
Abstract: Lubricin is a glycoprotein found in articular joints which has long been recognized as being an important biological boundary lubricant molecule and, more recently, an impressive antiadhesive that readily self-assembles into a well ordered, polymer brush layer on virtually any substrate. The lubricin molecule possesses an overabundance of anionic charge, a property that is atypical among antiadhesive molecules, that enables its use as a coating for applications involving electrokinetic processes such as electrophoresis and electroosmosis. Coating the surfaces of silica and polymeric microfluidic devices with self-assembled lubricin coatings affords a unique combination of excellent fouling resistance and high charge density that enables notoriously "sticky" biomolecules such as proteins to be used and controlled electrokinetically in the device without complications arising from nonspecific adsorption. Using capillary electrophoresis, we characterized the stability, uniformity, and electrokinetic properties of lubricin coatings applied to silica and PTFE capillaries over a range of run buffer pHs and when exposed to concentrated solutions of protein. In addition, we demonstrate the effectiveness of lubricin as a coating to minimize nonspecific protein adsorption in an electrokinetically controlled polydimethylsiloxane/silica microfluidic device.
Publisher: Elsevier BV
Date: 10-2005
DOI: 10.1016/J.BIOMATERIALS.2005.03.025
Abstract: In this study, we quantified the adsorption of immunoglobulin G (IgG) protein onto several polyelectrolyte-modified sintered porous polyethylene (PPE) membranes. The polymer surfaces had both cationic and anionic charges obtained via the adsorption of polyethylenimine (PEI) and polyacrylic acid (PAA), respectively, onto plasma-activated PPE. The amount of IgG adsorption was determined by measuring the gamma radiation emitted by [125I]-IgG radio labeled protein. By studying the impact of pH and ionic strength on IgG adsorption, we attempted to characterize the role and nature of the electrostatic interactions involved in the adsorption process to better understand how these interactions were influenced by the charge and structure of immobilized polyelectrolyte complexes at modified membrane surfaces. We were able to show that surface modification of PPE membranes with adsorbed PEI monolayers and PEI-PAA bilayers can greatly improve the IgG binding ability of the membrane under optimized conditions. We also showed that the observed improvement in the IgG binding is derived from electrostatic interactions between IgG and the polyelectrolyte surface. In addition, we found that the greatest IgG adsorption occurred when the IgG and the surface possessed predominantly opposite charges, rather than when the surface possessed the greatest electrostatic charge. Finally, we have found that the molecular weight of the terminating polyelectrolyte has a noticeable effect upon the electrostatic interactions between IgG and the PEI-PAA bilayer-modified PPE surfaces.
Publisher: American Chemical Society (ACS)
Date: 25-03-2021
Publisher: Elsevier BV
Date: 10-2023
Publisher: American Chemical Society (ACS)
Date: 22-02-2022
Publisher: The Electrochemical Society
Date: 23-07-2018
Abstract: New solid-state materials for energy storage devices are investigated due to their potential to achieve, for ex le, high reliability and safety as well as high energy density. Of the numerous battery chemistries possible, lithium-ion has become one of the most common technologies for portable electronics and is increasingly employed in electric vehicles and stationary storage. We have investigated a range of pyrrolidinium and phosphonium based organic ionic plastic crystals (OIPCs), made entirely of ions, that can be applied as attractive, high safety, solid-state electrolytes for lithium batteries.[1,2] These materials offer attractive stable electrolyte properties and unique interfacial properties,[3] key to the use of high energy density electrodes such as lithium metal. Inherently, OIPCs allow flexibility of design and improve safety due to their advantages as non-volatile components of solid-state devices. In general, the ionic conductivity of OIPCs has been too low for application at ambient temperatures. This presentation will provide an overview of the progress of these materials towards their use in practical solid-state lithium (and sodium) based batteries, including the use of nanoscale polymer composites and the complex role of phase behaviour with addition of lithium and sodium salts.[4-6] Solid-state Li metal | LFP and Li metal | NMC cells with excellent stability and ambient temperature operation are also described.[6,7] References: MacFarlane, D. R., Meakin, P., Sun, J., Amini, N. & Forsyth M., Pyrrolidinium Imides: A New Family of Molten Salts and Conductive Plastic Crystal Phases, Phys. Chem. B , 103 , 4164 (1999). Jin, L., Howlett, P. C., Pringle, J. M., Janikowski, J., Armand, M., MacFarlane, D. R. & Forsyth, M. An organic ionic plastic crystal electrolyte for rate capability and stability of ambient temperature lithium batteries. Energy Environ. Sci. 7, 3352 (2014). Howlett, P. C., Shekibi, Y., MacFarlane, D. R. & Forsyth M., Li-Metal Symmetrical Cell Studies Using Ionic Organic Plastic Crystal Electrolyte, Eng. Mater. , 11 , 1044 (2009). Howlett, P. C., Ponzio, F., Fang, J., Lin, T., Jin, L., Iranipour, N. & Efthimiadis, Thin and Flexible Solid-State Organic Ionic Plastic Crystal-Polymer Nanofibre Composite Electrolytes for Device Applications. Chem. Chem. Phys. 15 , 13784 (2013). Iranipour, N., Gunzelmann, D. J., Seeber, A., Vongsvivut, J., Doherty, C., Ponzio, F., O’Dell, L. A., Hollenk , A. F., Forsyth, M., Howlett, P. C., Ionic Transport Through a Composite Structure of N -ethyl- N -methylpyrrolidinium tetrafluoroborate Organic Ionic Plastic Crystals Reinforced with Polymer Nanofibres. Mater. Chem. A. 3 , 6038 (2015). Zhou, Y. Wang, X. Zhu, H. Armand, M. Forsyth, M. Greene, G. W. Pringle, J. M. Howlett, P. C. N-Ethyl-N-Methylpyrrolidinium Bis(Fluorosulfonyl)Imide-Electrospun Polyvinylidene Fluoride Composite Electrolytes: Characterization and Lithium Cell Studies. Chem. Chem. Phys. , 19, 2225 (2017). Wang, X. Zhu, H. Greene, G. W. Zhou, Y. Yoshizawa-Fujita, M. Miyachi, Y. Armand, M. Forsyth, M. Pringle, J. M. Howlett, P. C. Organic Ionic Plastic Crystal-Based Composite Electrolyte with Surface Enhanced Ion Transport and Its Use in All-Solid-State Lithium Batteries. Mater. Technol. 8, 1700046 (2017).
Publisher: American Chemical Society (ACS)
Date: 08-10-2015
Abstract: Understanding the amalgamation mechanisms between mercury and gold is of fundamental interest and importance to many mercury sensing applications. However, there is only limited and piecemeal discussion in the literature of the mechanisms by which Au-Hg amalgams are formed on thin Au films. Here, we present a comprehensive description of a series of morphological changes occurring in a thin polycrystalline Au film during Au-Hg amalgamation investigated by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and atomic force microscopy (AFM). These microscopic investigations enable us to offer a coherent explanation for the features and the mechanisms of amalgamation of Hg with Au in the film. We also use an optical technique (fringes of equal chromatic order, FECO) to observe changes in optical thickness and reflectivity of the film. Amalgamation reactions in the film render it inhomogeneous, thus making optical techniques unsuitable as a method for quantitative monitoring of Hg vapor using Au films of this type.
Publisher: Wiley
Date: 07-2020
Publisher: American Chemical Society (ACS)
Date: 03-2004
DOI: 10.1021/LA036048I
Abstract: Hydrophilic and chemically reactive porous media were prepared by adsorbing functional polymers at the surface of sintered polyethylene membranes. Modification of the membrane was accomplished by first exposing the membrane to an oxygen glow discharge gas plasma to introduce an electrostatic charge at the membrane surfaces. Cationic polyelectrolyte polyethylenimine (PEI) was adsorbed from solution to the anionic-charged surface to form an adsorbed monolayer. The adsorption of a second anionic polyelectrolyte onto the PEI layer allows further modification of the membrane surface to form a polyelectrolyte-bilayer complex. The conformation and stability of the adsorbed monolayers and bilayers comprising the modified surface are probed as a function of the polymer structure, charge density, and solubility. Using X-ray photoelectron spectroscopy analysis, we demonstrate that the presence of the polyelectrolyte multilayers drastically increases the density and specificity of the functional groups at the surface, more than what can be achieved through the plasma modification alone. Also, using the wicking rate of deionized, distilled water through the porous membrane to gauge the interfacial energy of the modified surface, we show that the membrane wicking rate can be controlled by varying the chemistry of the adsorbing polyelectrolytes and, to a lesser extent, by adjusting the polarity or ionic strength of the polyelectrolyte solution.
Publisher: Proceedings of the National Academy of Sciences
Date: 13-01-2009
Abstract: Actin protein is a major component of the cell cytoskeleton, and its ability to respond to external forces and generate propulsive forces through the polymerization of filaments is central to many cellular processes. The mechanisms governing actin's abilities are still not fully understood because of the difficulty in observing these processes at a molecular level. Here, we describe a technique for studying actin–surface interactions by using a surface forces apparatus that is able to directly visualize and quantify the collective forces generated when layers of noninterconnected, end-tethered actin filaments are confined between 2 (mica) surfaces. We also identify a force-response mechanism in which filaments not only stiffen under compression, which increases the bending modulus, but more importantly generates opposing forces that are larger than the compressive force. This elastic stiffening mechanism appears to require the presence of confining surfaces, enabling actin filaments to both sense and respond to compressive forces without additional mediating proteins, providing insight into the potential role compressive forces play in many actin and other motor protein-based phenomena.
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6TA02817A
Abstract: Organic ionic plastic crystal (OIPC) modified poly(vinylidene difluoride) (PVDF) composite fiber membrane with enhanced ion dynamics and almost pure β-PVDF are demonstrated.
Publisher: Wiley
Date: 26-02-2013
Publisher: American Chemical Society (ACS)
Date: 05-11-2020
Abstract: Surface fouling is a major problem faced by bionic implants (e.g., cochlear implants, pacemakers), where the adsorption of unwanted biomolecules has a detrimental effect on interfacial charge transfer processes, which severely impairs their capacity to sense and transmit electrical signals with high fidelity. Polypyrrole (PPy) is a conductive polymer whose naturally high impedance, ionic and electric conductivity, mechanical "softness", and biocompatibility make it a leading candidate for next-generation neural electrode interfaces. However, PPy (and related conductive polymer) surfaces are susceptible to surface fouling upon exposure to biological fluids (e.g., blood, perilymph, saliva), which compromises performance and shortens its expected working lifespan. Here, we report the ability of lubricin (LUB) coatings, a rapidly self-assembling, biological antiadhesive glycoprotein, to mitigate the harmful electrochemical effects caused by the surface fouling of electrochemically grown PPy films. LUB, a biological antiadhesive glycoprotein, undergoes rapid self-assembly and adheres strongly to most interfaces, including PPy, resulting in an easy-to-apply and highly efficacious coating. The LUB-coated PPy electrodes are electrochemically characterized, and its antifouling properties are assessed against concentrated solutions of bovine serum albumin (BSA) and following long-term exposure to artificial perilymph (AP). Periodic impedance measurement conducted over 6 days in AP solution demonstrates the high stability and capacity of the LUB coatings to maintain stable impedance values under real-world mimicking conditions.
Publisher: American Chemical Society (ACS)
Date: 17-04-2013
DOI: 10.1021/BM400327A
Abstract: Normal (e.g., adhesion) and lateral (friction) forces were measured between physisorbed and chemically grafted layers of hyaluronic acid (HA), an anionic polyelectrolyte in the presence of lubricin (Lub), a mucinous glycoprotein, on mica surfaces using a surface forces apparatus (SFA). This work demonstrates that high friction coefficients between the surfaces do not necessarily correlate with surface damage and that chemically grafted HA acts synergistically with Lub to provide friction reduction and enhanced wear protection to the surfaces. Surface immobilization of HA by grafting is necessary for such wear protection. Increasing the concentration of Lub enhances the threshold load that a chemically grafted HA surface can be subjected to before the onset of wear. Addition of Lub does not have any beneficial effect if HA is physisorbed to the mica surfaces. Damage occurs at loads less than 1 mN regardless of the amount of Lub, indicating that the molecules in the bulk play little or no role in protecting the surfaces from damage. Lub penetrates into the chemically bound HA to form a visco-elastic gel that reduces the coefficient of friction as well as boosts the strength of the surface against abrasive wear (damage).
Publisher: American Chemical Society (ACS)
Date: 14-11-2022
DOI: 10.1021/ACSSENSORS.2C01460
Abstract: Improving outcomes for cancer patients during treatment and monitoring for cancer recurrence requires personalized care which can only be achieved through regular surveillance for biomarkers. Unfortunately, routine detection for blood-based biomarkers is cost-prohibitive using currently specialized laboratories. Using a rapid self-assembly sensing interface amenable to methods of mass production, we demonstrate the ability to detect and quantify a small carbohydrate-based cancer biomarker, Tn antigen (αGalNAc-Ser/Thr) in a small volume of blood, using a test format strip reminiscent of a blood glucose test. The detection of Tn antigen at picomolar levels is achieved through a new transduction mechanism based on the impact of Tn antigen interactions on the molecular dynamic motion of a lectin cross-linked lubricin antifouling brush. In tests performed on retrospective blood plasma s les from patients presenting three different tumor types, differentiation between healthy and diseased patients was achieved, highlighting the clinical potential for cancer monitoring.
Publisher: Wiley
Date: 05-02-2018
Publisher: Proceedings of the National Academy of Sciences
Date: 07-03-2011
Abstract: Articular cartilage is a highly efficacious water-based tribological system that is optimized to provide low friction and wear protection at both low and high loads (pressures) and sliding velocities that must last over a lifetime. Although many different lubrication mechanisms have been proposed, it is becoming increasingly apparent that the tribological performance of cartilage cannot be attributed to a single mechanism acting alone but on the synergistic action of multiple “modes” of lubrication that are adapted to provide optimum lubrication as the normal loads, shear stresses, and rates change. Hyaluronic acid (HA) is abundant in cartilage and synovial fluid and widely thought to play a principal role in joint lubrication although this role remains unclear. HA is also known to complex readily with the glycoprotein lubricin (LUB) to form a cross-linked network that has also been shown to be critical to the wear prevention mechanism of joints. Friction experiments on porcine cartilage using the surface forces apparatus, and enzymatic digestion, reveal an “adaptive” role for an HA-LUB complex whereby, under compression, nominally free HA diffusing out of the cartilage becomes mechanically, i.e., physically, trapped at the interface by the increasingly constricted collagen pore network. The mechanically trapped HA-LUB complex now acts as an effective (chemically bound) “boundary lubricant”—reducing the friction force slightly but, more importantly, eliminating wear damage to the rubbing/shearing surfaces. This paper focuses on the contribution of HA in cartilage lubrication however, the system as a whole requires both HA and LUB to function optimally under all conditions.
Publisher: Elsevier BV
Date: 03-2007
Publisher: American Chemical Society (ACS)
Date: 16-11-2020
Publisher: American Chemical Society (ACS)
Date: 26-04-2019
Abstract: Preventing the unwanted adsorption of proteins and cells at articular cartilage surfaces plays a critical role in maintaining healthy joints and avoiding degenerative diseases such as osteoarthritis. Immobilized at the surface of healthy articular cartilage is a thin, interfacial layer of macromolecules consisting mainly of hyaluronic acid (HA) and lubricin (LUB a.k.a. PRG4) that is believed to form a co-adsorbed, composite film now known to exhibit synergistic tribological properties. Bioinspired by the composition of cartilage surfaces, composite layers of HA and LUB were grafted to Au surfaces and the antiadhesive properties were assessed using surface plasmon resonance and quartz crystal microbalance. A clear synergistic enhancement in antiadhesive properties was observed in the composite films relative to grafted HA and LUB layers alone. Atomic force microscopy (AFM) normal force measurements provide insight into the architecture of the HA/LUB composite layer and implicate a strong contribution of hydrophobic interactions in the binding of LUB end-domains directly to HA chains. These AFM force measurements indicate that the adhesion of LUB to HA is strong and indicate that the hydrophobic coupling of LUB to HA shields the hydrophobic domains in these molecules from interactions with other proteins or molecules.
Publisher: Elsevier BV
Date: 10-2016
Publisher: American Chemical Society (ACS)
Date: 09-2016
Publisher: American Chemical Society (ACS)
Date: 22-12-2011
DOI: 10.1021/LA203851W
Abstract: High molecular weight hyaluronic acid (HA) is present in articular joints and synovial fluid at high concentrations yet despite numerous studies, the role of HA in joint lubrication is still not clear. Free HA in solution does not appear to be a good lubricant, being negatively charged and therefore repelled from most biological, including cartilage, surfaces. Recent enzymatic experiments suggested that mechanically or physically (rather than chemically) trapped HA could function as an "adaptive" or "emergency" boundary lubricant to eliminate wear damage in shearing cartilage surfaces. In this work, HA was chemically grafted to a layer of self-assembled amino-propyl-triethoxy-silane (APTES) on mica and then cross-linked. The boundary lubrication behavior of APTES and of chemically grafted and cross-linked HA in both electrolyte and lipid 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) solutions was tested with a surface forces apparatus (SFA). Despite the high coefficient of friction (COF) of μ ≈ 0.50, the chemically grafted HA gel significantly improved the lubrication behavior of HA, particularly the wear resistance, in comparison to free HA. Adding more DOPC lipid to the solution did not improve the lubrication of the chemically grafted and cross-linked HA layer. Damage of the underlying mica surface became visible at higher loads (pressure >2 MPa) after prolonged sliding times. It has generally been assumed that damage caused by or during sliding, also known as "abrasive friction", which is the main biomedical/clinical/morphological manifestation of arthritis, is due to a high friction force and, therefore, a large COF, and that to prevent surface damage or wear (abrasion) one should therefore aim to reduce the COF, which has been the traditional focus of basic research in biolubrication, particularly in cartilage and joint lubrication. Here we combine our results with previous ones on grafted and cross-linked HA on lipid bilayers, and lubricin-mediated lubrication, and conclude that for cartilage surfaces, a high COF can be associated with good wear protection, while a low COF can have poor wear resistance. Both of these properties depend on how the lubricating molecules are attached to and organized at the surfaces, as well as the structure and mechanical, viscoelastic, elastic, and physical properties of the surfaces, but the two phenomena are not directly or simply related. We also conclude that to provide both the low COF and good wear protection of joints under physiological conditions, some or all of the four major components of joints-HA, lubricin, lipids, and the cartilage fibrils-must act synergistically in ways (physisorbed, chemisorbed, grafted and/or cross-linked) that are still to be determined.
Publisher: Elsevier BV
Date: 03-2022
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C3SM52106K
Abstract: Articular cartilage is an ex le of a highly efficacious water-based, natural lubrication system that is optimized to provide low friction and wear protection at both low and high loads and sliding velocities. One of the secrets of cartilage's superior tribology comes from a unique, multimodal lubrication strategy consisting of both a fluid pressurization mediated lubrication mechanism and a boundary lubrication mechanism supported by surface bound macromolecules. Using a reconstituted network of highly interconnected cellulose fibers and simple modification through the immobilization of polyelectrolytes, we have recreated many of the mechanical and chemical properties of cartilage and the cartilage lubrication system to produce a purely synthetic material system that exhibits some of the same lubrication mechanisms, time dependent friction response, and high wear resistance as natural cartilage tissue. Friction and wear studies demonstrate how the properties of the cellulose fiber network can be used to control and optimize the lubrication and wear resistance of the material surfaces and highlight what key features of cartilage should be duplicated in order to produce a cartilage-mimetic lubrication system.
Publisher: Elsevier BV
Date: 06-2004
Publisher: American Chemical Society (ACS)
Date: 13-08-2012
DOI: 10.1021/LA3018216
Abstract: We present a newly designed electrochemical surface forces apparatus (EC-SFA) that allows control and measurement of surface potentials and interfacial electrochemical reactions with simultaneous measurement of normal interaction forces (with nN resolution), friction forces (with μN resolution), and distances (with Å resolution) between apposing surfaces. We describe three applications of the developed EC-SFA and discuss the wide-range of potential other applications. In particular, we describe measurements of (1) force-distance profiles between smooth and rough gold surfaces and apposing self-assembled monolayer-covered smooth mica surfaces (2) the effective changing thickness of anodically growing oxide layers with Å-accuracy on rough and smooth surfaces and (3) friction forces evolving at a metal-ceramic contact, all as a function of the applied electrochemical potential. Interaction forces between atomically smooth surfaces are well-described using DLVO theory and the Hogg-Healy-Fuerstenau approximation for electric double layer interactions between dissimilar surfaces, which unintuitively predicts the possibility of attractive double layer forces between dissimilar surfaces whose surface potentials have similar sign, and repulsive forces between surfaces whose surface potentials have opposite sign. Surface roughness of the gold electrodes leads to an additional exponentially repulsive force in the force-distance profiles that is qualitatively well described by an extended DLVO model that includes repulsive hydration and steric forces. Comparing the measured thickness of the anodic gold oxide layer and the charge consumed for generating this layer allowed the identification of its chemical structure as a hydrated Au(OH)(3) phase formed at the gold surface at high positive potentials. The EC-SFA allows, for the first time, one to look at complex long-term transient effects of dynamic processes (e.g., relaxation times), which are also reflected in friction forces while tuning electrochemical surface potentials.
Publisher: Informa UK Limited
Date: 06-06-2019
DOI: 10.1080/07388551.2019.1616668
Abstract: Applications of biotechnological tools in food preservation have shown promising results in minimizing food spoilage. Design and development of highly efficient food preservatives are one of the key success factors in this application field. However, due to the inherent shortcomings of the bulk forms of such preservatives, research was in progress to find suitable alternatives to replace conventional modalities. The intervention of nanotechnology has made this approach feasible in almost every aspect of food preservation. This interface domain of nanobiotechnology has been very well explored in the last few decades and vast literature has been reported. Researchers have developed efficient nanopreservatives (NPRs) for erse applications. However, the literature available on nano-based food preservation is not inclusive of molecular perspectives involved in food preservation. There is a large knowledge gap in the interface domain concerning the physics of intermolecular and interfacial forces and nanotechnology which play decisive roles in designing edible coatings (ECs). There is an urgent need for identifying the nano and molecular level contributing factors for developing efficient NPRs. Moreover, it is imperative to understand the possible health impact of NPRs in public interest and concern. This review revisits the fundamental aspects of food preservation and navigates through the applicability, safety, molecular aspects and future direction of NPRs.
Publisher: American Geophysical Union (AGU)
Date: 08-2006
DOI: 10.1029/2005JB004010
Publisher: Royal Society of Chemistry (RSC)
Date: 2020
DOI: 10.1039/C9TA12827A
Abstract: The interactions between OIPCs and polymer nanoparticles create interfacial layers that control the ion mobility of the resulting composite.
Publisher: Elsevier BV
Date: 09-2023
Publisher: American Chemical Society (ACS)
Date: 10-09-2021
Publisher: IOP Publishing
Date: 27-01-2010
Publisher: Elsevier BV
Date: 04-2022
DOI: 10.1016/J.JENVMAN.2022.114655
Abstract: Per- oly-fluoroalkyl substances (PFAS) are an emerging class of environmental contaminants used as an additive across various commodity and fire-retardant products, for their unique thermo-chemical stability, and to alter their surface properties towards selective liquid repellence. These properties also make PFAS highly persistent and mobile across various environmental compartments, leading to bioaccumulation, and causing acute ecotoxicity at all trophic levels particularly to human populations, thus increasing the need for monitoring at their repositories or usage sites. In this review, current nano-enabled methods towards PFAS sensing and its monitoring in wastewater are critically discussed and benchmarked against conventional detection methods. The discussion correlates the materials' properties to the sensitivity, responsiveness, and reproducibility of the sensing performance for nano-enabled sensors in currently explored electrochemical, spectrophotometric, colorimetric, optical, fluorometric, and biochemical with limits of detection of 1.02 × 10
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C2SM26545A
Publisher: Wiley
Date: 25-01-2011
Publisher: American Vacuum Society
Date: 03-2021
DOI: 10.1116/6.0000779
Abstract: The ability to prevent or minimize the accumulation of unwanted biological materials on implantable medical devices is important in maintaining the long-term function of implants. To address this issue, there has been a focus on materials, both biological and synthetic, that have the potential to prevent device fouling. In this review, we introduce a glycoprotein called lubricin and report on its emergence as an effective antifouling coating material. We outline the versatility of lubricin coatings on different surfaces, describe the physical properties of its monolayer structures, and highlight its antifouling properties in improving implant compatibility as well as its use in treatment of ocular diseases and arthritis. This review further describes synthetic polymers mimicking the lubricin structure and function. We also discuss the potential future use of lubricin and its synthetic mimetics as antiadhesive biomaterials for therapeutic applications.
Publisher: American Chemical Society (ACS)
Date: 28-02-2022
DOI: 10.1021/JACS.1C11545
Abstract: From atomic force microscopy (AFM) experiments, we report a new phenomenon in which the dissolution rate of fused silica is enhanced by more than 5 orders of magnitude by simply pressing a second, dissimilar surface against it and oscillating the contact pressure at low kHz frequencies in deionized water. The silica dissolution rate enhancement was found to exhibit a strong dependence on the pressure oscillation frequency consistent with a resonance effect. This harmonic enhancement of the silica dissolution rate was only observed at asymmetric material interfaces (e.g., diamond on silica) with no evidence of dissolution rate enhancement observed at symmetric material interfaces (i.e., silica on silica) within the experimental time scales. The apparent requirement for interface dissimilarity, the results of analogous experiments performed in anhydrous dodecane, and the observation that the silica "dissolution pits" continue to grow in size under contact stresses well below the silica yield stress refute a mechanical deformation or chemo-mechanical origin to the observed phenomenon. Instead, the silica dissolution rate enhancement exhibits characteristics consistent with a previously described 'electrochemical pressure solution' mechanism, albeit, with greatly lified kinetics. Using a framework of electrochemical pressure solution, an electrochemical model of mineral dissolution, and a recently proposed "surface resonance" theory, we present an electro-chemo-mechanical mechanism that explains how oscillating the contact pressure between dissimilar surfaces in water can lify surface dissolution rates by many orders of magnitude. This reaction rate enhancement mechanism has implications not only for dissolution but also for potentially other reactions occurring at the solid-liquid interface, e.g. catalysis.
Publisher: Elsevier BV
Date: 05-2017
Publisher: Elsevier BV
Date: 05-2021
Publisher: Elsevier BV
Date: 11-2011
Publisher: Royal Society of Chemistry (RSC)
Date: 2012
DOI: 10.1039/C2SM26330K
Publisher: Elsevier BV
Date: 11-2018
Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D0MA00992J
Abstract: Ion dynamics enhancements derived from anion–polymer interactions are proposed in organic ionic plastic crystal–poly(vinylidene fluoride)composite electrolytes.
Publisher: Elsevier BV
Date: 11-2004
Publisher: Elsevier BV
Date: 07-2023
Publisher: American Chemical Society (ACS)
Date: 11-03-2022
Abstract: Employing high-voltage Ni-rich cathodes in Li metal batteries (LMBs) requires stabilization of the electrode/electrolyte interfaces at both electrodes. A stable solid-electrolyte interphase (SEI) and suppression of active material pulverization remain the greatest challenges to achieving efficient long-term cycling. Herein, studies of NMC622 (1 mAh cm
Publisher: American Chemical Society (ACS)
Date: 24-04-2022
DOI: 10.1021/ACS.LANGMUIR.1C02970
Abstract: There are numerous biomedical applications where the interfacial shearing of surfaces can cause wear and friction, which can lead to a variety of medical complications such as inflammation, irritation, and even bacterial infection. We introduce a novel nanomaterial additive comprised of two-dimensional graphene oxide nanosheets (2D-NSCs) coated with lubricin (LUB) to reduce the amount of tribological stress in biomedical settings, particularly at low shear rates where boundary lubrication dominates. LUB is a glycoprotein found in the articular joints of mammals and has recently been discovered as an ocular surface boundary lubricant. The ability of LUB to self-assemble into a "telechelic" brush layer on a variety of surfaces was exploited here to coat the top and bottom surfaces of the ultrathin 2D-NSCs in solution, effectively creating a biopolymer-coated nanosheet. A reduction in friction of almost an order of magnitude was measured at a bioinspired interface. This reduction was maintained after repeated washing (5×), suggesting that the large aspect ratio of the 2D-NSCs facilitates effective lubrication even at diluted concentrations. Importantly, and unlike LUB-only treatment, the lubrication effect can be eliminated over 15 rinsing cycles, suggesting that the LUB-coated 2D-NSCs do not exhibit any binding interactions with the shearing surfaces. The effective lubricating properties of the 2D-NSCs combined with full reversibility through rinsing make the LUB-coated 2D-NSCs an intriguing candidate as a lubricant for biomedical applications.
Publisher: Informa UK Limited
Date: 2005
Publisher: American Chemical Society (ACS)
Date: 31-05-2003
DOI: 10.1021/LA026940+
Abstract: This paper examines the wetting characteristics of porous polyethylene surfaces modified by exposure to reactive oxygen glow discharge gas plasma, through the direct measurement of the wicking properties of the modified material. It is well-known that oxygen plasma can be used to chemically alter the surface of polyethylene to enhance wetting properties. Chemical and physical modification of a polymer's surface is the consequence of reactions initiated by the collision of high-energy species in the plasma with the polymer surface. The conditions of the plasma treatment, such as electric field strength (power), exposure time, and chamber pressure, govern the frequency and energy of collisions and, thus, determine the nature and degree of the chemical modification of the polyethylene surface. Comparisons of the chemical modification of sintered porous polyethylene surfaces achieved through treatments with reactive oxygen glow discharge gas plasmas generated at various powers, chamber pressures, and times of exposure were made by measuring the wicking rate of distilled and deionized water in the modified materials. A strong correlation was observed between the electric field power used to generate the plasma and the degree of chemical modification of the polyethylene surfaces. In addition, the rate of chemical modification was also found to be a function of the electric field power.
Publisher: Proceedings of the National Academy of Sciences
Date: 04-08-2011
Publisher: American Chemical Society (ACS)
Date: 20-07-2021
Publisher: American Chemical Society (ACS)
Date: 02-03-2017
DOI: 10.1021/ACS.LANGMUIR.6B03992
Abstract: Lubricin (LUB) is a "mucin-like" glycoprotein found in synovial fluids and coating the cartilage surfaces of articular joints, which is now generally accepted as one of the body's primary boundary lubricants and antiadhesive agents. LUB's superior lubrication and antiadhesion are believed to derive from its unique interfacial properties by which LUB molecules adhere to surfaces (and biomolecules, such as hyaluronic acid and collagen) through discrete interactions localized to its two terminal end domains. These regionally specific interactions lead to self-assembly behavior and the formation of a well-ordered "telechelic" polymer brush structure on most substrates. Despite its importance to biological lubrication, detailed knowledge on the LUB's self-assembled brush structure is insufficient and derived mostly from indirect and circumstantial evidence. Neutron reflectometry (NR) was used to directly probe the self-assembled LUB layers, confirming the polymer brush architecture and resolving the degree of hydration and level of surface coverage. While attempting to improve the LUB contrast in the NR measurements, the LUB layers were exposed to a 20 mM solution of CaCl
Publisher: Elsevier BV
Date: 10-2019
Publisher: Royal Society of Chemistry (RSC)
Date: 2017
DOI: 10.1039/C6CP07415D
Abstract: LiFSI doped [C 2 mpyr][FSI]–PVdF composites were developed as solid-state, self-standing electrolyte membranes.
Publisher: Elsevier BV
Date: 09-2015
Publisher: American Society of Clinical Oncology (ASCO)
Date: 06-2023
Publisher: American Chemical Society (ACS)
Date: 29-07-2019
DOI: 10.1021/ACS.LANGMUIR.9B01809
Abstract: Lubricin (LUB, aka PRG4), a mucin-like glycoprotein, is best known for the significant role it plays in the boundary lubrication, wear protection, and adhesion control systems in human joints. However, LUB exhibits a number of erse and useful properties, including a remarkable ability to self-assemble into a telechelic brush structure onto virtually any substrate. This self-assembly behavior has spawned the emergence of numerous nontraditional applications of LUB coatings in numerous areas such as microfluidics, electrochemical sensors, contact lenses, antifouling surfaces, and bionic neural interfaces. Although LUB will readily self-assemble on most substrates, it has become apparent that the substrate has a significant influence on the LUB layer's demonstrated lubrication, antiadhesion, electrokinetic, and size-selective transport properties however, investigations into LUB-substrate interactions and how they influence the self-assembled LUB layer structure remain a neglected aspect of LUB research. This study utilizes AFM force spectroscopy to directly assess the adhesion energy of LUB molecules adsorbed to a wide variety of different substrates which include inorganic, polymeric, and metallic materials. An analysis of the steric repulsive forces measured on approach provides a qualitative assessment of the LUB layer's mechanical modulus, related to the chain packing density, across substrates. These modulus measurements, combined with characteristic features and the dwell time dependence of the LUB adhesion forces provide insight into the organization and uniformity of the LUB brush structure. The results of these measurements indicate that LUB interactions with different substrates are highly variable and substrate-specific, resulting in a surprisingly broad spectrum of adhesion energies and layer properties (i.e., chain density, uniformity, etc.) which are not, themselves, correlated or easily predicted by substrate properties. In addition, this study finds exceptionally poor LUB adhesion to both mica and poly(methyl methacrylate) surfaces that remain widely used substrates for constructing model surfaces in fundamental tribology studies which may have significant implications for the findings of a number of foundational studies into LUB tribology and molecular synergies.
Publisher: Wiley
Date: 04-05-2017
Publisher: Wiley
Date: 03-2023
Abstract: A new method of direct‐write nanolithography that is able to rapidly etch silica surfaces under a scanning atomic force microscopy (AFM) probe in tapping mode (TM) is reported. In this lithography technique, silica surfaces are etched using a recently described electro‐chemo‐mechanical phenomenon of frequency enhanced electrochemical pressure solution (FEEPS). In FEEPS, the tapping of the AFM tip generates oscillations of the Stern potential at the silica‐water interface that can accelerate the silica dissolution kinetics by more than 5–6 orders of magnitude when surface resonance states are achieved i.e., when the oscillation frequency is in phase with the dynamics of interfacial chemical reaction steps. By scanning silica surfaces in TM, silica is selectively dissolved below the tapping tip as it is scanned. The FEEPS accelerated silica dissolution rates can generate etched features with depths of more than 60 nm in a single AFM tip pass. The rate of etching can be controlled easily by varying the scanning rate or by modulating the tapping frequency. This fine control over the silica etching process and because material is removed (dissolved) rather than displaced as with nanoscratching, the FEEPS process lends itself to gray‐scale nanolithography which is demonstrated.
Publisher: Elsevier BV
Date: 05-2009
Publisher: American Chemical Society (ACS)
Date: 08-12-2007
DOI: 10.1021/LA702383N
Abstract: Lubricin (LUB) is a glycoprotein of the synovial cavity of human articular joints, where it serves as an antiadhesive, boundary lubricant, and regulating factor for the cartilage surface. It has been proposed that these properties are related to the presence of a long, extended, heavily glycosylated and highly hydrated mucinous domain in the central part of the LUB molecule. In this work, we show that LUB has a contour length of 220 +/- 30 nm and a persistence length of < or =10 nm. LUB molecules aggregate in oligomers where the protein extremities are linked by disulfide bonds. We have studied the effect of proteolytic digestion by chymotrypsin and removal of the disulfide bonds, both of which mainly affect the N- and C- terminals of the protein, on the adsorption, normal forces, friction (lubrication) forces, and wear of LUB layers adsorbed on smooth, negatively charged mica surfaces, where the protein naturally forms lubricating polymer brush-like layers. After in situ digestion, the surface coverage was drastically reduced, the normal forces were altered, and both the coefficient of friction and the wear were dramatically increased (the COF increased to mu = 1.1-1.9), indicating that the mucinous domain was removed from the surface. Removal of disulfide bonds did not change the surface coverage or the overall features of the normal forces however, we find an increase in the friction coefficient from mu = 0.02-0.04 to mu = 0.13-1.17 in the pressure regime below 6 atm, which we attribute to a higher affinity of the protein terminals for the surface. The necessary condition for LUB to be a good lubricant is that the protein be adsorbed to the surface via its terminals, leaving the central mucin domain free to form a low-friction, surface-protecting layer. Our results suggest that this "end-anchoring" has to be strong enough to impart the layer a sufficient resistance to shear, but without excessively restricting the conformational freedom of the adsorbed proteins.
Publisher: American Chemical Society (ACS)
Date: 19-09-2019
DOI: 10.1021/ACS.LANGMUIR.9B02063
Abstract: Surfaces are abundant in living systems, such as in the form of cellular membranes, and govern many biological processes. In this study, the adsorption of the amyloidogenic model peptides GNNQQNY, NNFGAIL, and VQIVYK as well as the amyloid-forming antimicrobial peptide uperin 3.5 (U3.5) were studied at low concentrations (100 μM) to different surfaces. The technique of a quartz crystal microbalance with dissipation monitoring (QCM-D) was applied as it enables the monitoring of mass binding to sensors at nanogram sensitivity. Gold-coated quartz sensors were used as unmodified gold surfaces or functionalized with self-assembled monolayers (SAMs) of alkanethiols (terminated as methyl, amino, carboxyl, and hydroxyl) resulting in different adsorption affinities of the peptides. Our objective was to evaluate the underlying role of the nature and feature of interfaces in biological systems which could concentrate peptides and impact or trigger peptide aggregation processes. In overall, the largely hydrophobic peptides adsorbed with preference to hydrophobic or countercharged surfaces. Further, the glycoprotein lubricin (LUB) was tested as an antiadhesive coating. Despite its hydrophilicity, the adsorption of peptides to LUB coated sensors was similar to the adsorption to unmodified gold surfaces, which indicates that some peptides diffused through the LUB layer to reach the underlying gold sensor surface. The LUB protein-antiadhesive is thus more effective as a biomaterial coating against larger biomolecules than small peptides under the conditions used here. This study provides directions toward a better understanding of amyloid peptide adsorption to biologically relevant interfaces, such as cellular membranes.
Publisher: Elsevier BV
Date: 09-2016
DOI: 10.1016/J.JCIS.2016.06.030
Abstract: Silkworm silk fibers are core-shell composites of fibroin and sericin proteins. Studying the interactions between fibroin and sericin is essential for understanding the properties of these composites. It is observed that compared to the domestic silk cocoon Bombyx mori (B. mori), the adhesion between fibroin and sericin from the wild silk cocoon, Antheraea pernyi (A. pernyi), is significantly stronger with a higher degree of heterogeneity. The adsorption of A. pernyi sericin on its fibroin is almost twice the value for B. mori sericin on fibroin, both showing a monolayer Langmuir adsorption. (1)H NMR and FTIR studies demonstrate on a molecular level the stronger interactions and the more intensive complex formation between A. pernyi fibroin and sericin, facilitated by the hydrogen bonding between glycine and serine. The findings of this study may help the design of composites with superior interfacial adhesion between different components.
Publisher: Elsevier BV
Date: 04-2010
DOI: 10.1016/J.BIOMATERIALS.2010.01.102
Abstract: A compression cell designed to fit inside an NMR spectrometer was used to investigate the in situ mechanical strain response, structural changes to the internal pore structure, and the diffusion and flow of interstitial water in full-thickness cartilage s les as it was deforming dynamically under a constant compressive load (pressure). We distinguish between the hydrostatic pressure acting on the interstitial fluid and the pore pressure acting on the cartilage fibril network. Our results show that properties related to the pore matrix microstructure such as diffusion and hydraulic conductivity are strongly influenced by the hydrostatic pressure in the interstitial fluid of the dynamically deforming cartilage which differ significantly from the properties measured under static i.e. equilibrium loading conditions (when the hydrostatic pressure has relaxed back to zero). The magnitude of the hydrostatic fluid pressure also appears to affect the way cartilage's pore matrix changes during deformation with implications for the diffusion and flow-driven fluid transport through the deforming pore matrix. We also show strong evidence for a highly anisotropic pore structure and deformational dynamics that allows cartilage to deform without significantly altering the axial porosity of the matrix even at very large strains. The insensitivity of the axial porosity to compressive strain may be playing a critical function in directing the flow of pressurized interstitial fluid in the compressed cartilage to the surface, to support the load, and provide a protective interfacial fluid film that 'weeps' out from the deforming tissue and thereby enhances the (elasto)hydrodynamic efficacy of sliding joints. Our results appear to show a close synergy between the structure of cartilage and both the hydrodynamic and boundary lubrication mechanisms.
Publisher: Elsevier BV
Date: 02-2020
Publisher: Elsevier BV
Date: 06-2006
Location: United States of America
Start Date: 2018
End Date: 12-2022
Amount: $618,912.00
Funder: Australian Research Council
View Funded ActivityStart Date: 05-2013
End Date: 06-2017
Amount: $375,000.00
Funder: Australian Research Council
View Funded ActivityStart Date: 05-2014
End Date: 12-2017
Amount: $270,000.00
Funder: Australian Research Council
View Funded Activity