ORCID Profile
0000-0003-1636-6448
Current Organisation
RMIT University
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Biomaterials | Regenerative Medicine (incl. Stem Cells and Tissue Engineering) | Biomedical Engineering
Expanding Knowledge in the Physical Sciences | Expanding Knowledge in the Biological Sciences |
Publisher: Wiley
Date: 08-10-2013
Publisher: Wiley
Date: 14-08-2020
Publisher: Wiley
Date: 30-09-2020
Publisher: Royal Society of Chemistry (RSC)
Date: 2014
DOI: 10.1039/C4TB00142G
Abstract: Investigating the influence of conductive polymer dopants on surface properties and chemistry, and how they may modify cardiac progenitor cell interactions.
Publisher: Public Library of Science (PLoS)
Date: 30-07-2015
Publisher: Cold Spring Harbor Laboratory
Date: 07-08-2020
DOI: 10.1101/2020.08.07.241646
Abstract: Hierarchical collagen fibers are the primary source of strength in musculoskeletal tendons, ligaments, and menisci. It has remained a challenge to develop these large fibers in engineered replacements or in vivo after injury. The objective of this study was to investigate the ability of restrained cell-seeded high density collagen gels to drive hierarchical fiber formation for multiple musculoskeletal tissues. We found boundary conditions applied to high density collagen gels were capable of driving tenocytes, ligament fibroblasts, and meniscal fibrochondrocytes to develop native-sized hierarchical collagen fibers 20-40 µm in diameter. The collagen fibers organize similar to native collagen with native fibril banding patterns and hierarchical fiber bundles 50-350 µm in diameter by 6 weeks. Mirroring fiber organization, tensile properties of restrained s les improved significantly with time, reaching ∼1 MPa. Additionally, tendon, ligament, and meniscal cells produced significantly different sized fibers, different degrees of crimp, and different GAG concentrations, which corresponded with respective native tissue. To our knowledge, these are some of the largest, most organized fibers produced to date in vitro . Further, cells produced tissue specific hierarchical fibers, suggesting this system is a promising tool to better understand cellular regulation of fiber formation to better stimulate it in vivo after injury.
Publisher: Elsevier BV
Date: 02-2021
Publisher: Elsevier BV
Date: 09-2013
DOI: 10.1016/J.BBAGEN.2013.03.005
Abstract: The interaction of ECM proteins is critical in determining the performance of materials used in biomedical applications such as tissue regeneration, implantable bionics and biosensing. To improve our understanding of ECM protein-conducting polymer interactions, we have used Atomic Force Microscopy (AFM) to elucidate the interactions of fibronectin (FN) on polypyrrole (PPy) doped with different glycosaminoglycans. We were able to classify four main types of FN interactions, including those related to 1) non-specific adhesion, 2) protein unfolding and subsequent unbinding from the surface, 3) desorption and 4) interactions with no adhesion. FN adhesion on PPy/hyaluronic acid showed a significantly lower density of surface adhesion with the adhesion restricted to nodule structures, as opposed to their peripheries, of the polymer morphology. In contrast, PPy/chondroitin sulfate showed a significantly higher density of surface adhesion to the point where the distribution of adhesion effectively masked the topography. Through conductive AFM imaging, we found that the conductive regions correlated with regions of FN adhesion. Given that the conductivity requires doping of the polymer, these findings suggest that FN adhesion is mediated by interactions with chondroitin sulfate and hyaluronic acid at the polymer surface and may be indicative of specific interactions due to contributions from electrostatic attraction between the FN and sulfate/anionic groups of the dopants. This study demonstrates the ability of AFM to resolve the protein-conducting polymer interactions at the molecular and nanoscale level, which will be important for interfacing these polymer materials with biological systems. This article is part of a Special Issue entitled Organic Bioelectronics - Novel Applications in Biomedicine.
Publisher: American Chemical Society (ACS)
Date: 13-09-2017
DOI: 10.1021/JACS.7B06591
Publisher: Elsevier BV
Date: 07-2012
DOI: 10.1016/J.ACTBIO.2012.03.023
Abstract: The interaction of proteins and cells with polymers is critical to their use in scientific and medical applications. In this study, plasma immersion ion implantation (PIII) was used to modify the surface of the conducting polymer, polypyrrole, which possesses electrical properties. PIII treatment enabled persistent, covalent binding of the cell adhesive protein, tropoelastin, without employing chemical linking molecules. In contrast tropoelastin was readily eluted from the untreated surface. Through this differential persistence of binding, surface bound tropoelastin supported cell adhesion and spreading on the PIII treated but not the untreated polypyrrole surface. The application of a steel shadow mask during PIII treatment allowed for spatial definition of tropoelastin exclusively to PIII treated regions. The general applicability of this approach to other extracellular matrix proteins was illustrated using collagen I, which displayed similar results to tropoelastin but required extended washing conditions. This approach allowed fine patterning of cell adhesion and spreading to tropoelastin and collagen, specifically on PIII treated polypyrrole regions. We therefore present a methodology to alter the functionality of polypyrrole surfaces, generating surfaces that can spatially control cellular interactions through protein functionalization with the potential for electrical stimulation.
Publisher: Wiley
Date: 17-10-2012
Abstract: Polymer-based electrodes for interfacing biological tissues are becoming increasingly sophisticated. Their many functions place them at the cross-roads of electromaterials, biomaterials, and drug-delivery systems. For conducting polymers, the mechanism of conductivity requires doping with anionic molecules such as extracellular matrix molecules, a process that distinguishes them as biomaterials and provides a means to control interactions at the cellular-electrode interface. However, due to their complex structure, directly observing the selective binding of target molecules or proteins has so far eluded researchers. This situation is compounded by the polymer's ability to adopt different electronic states that alter the polymer-dopant interactions. Here, the ability to resolve sub-molecular binding specificity between sulfate and carboxyl groups of dopants and heparin binding domains of human plasma fibronectin is demonstrated. The interaction exploits a form of biological 'charge complementarity' to enable specificity. When an electrical signal is applied to the polymer, the specific interaction is switched to a non-specific, high-affinity binding state that can be reversibly controlled using electrochemical processes. Both the specific and non-specific interactions are integral for controlling protein conformation and dynamics. These details, which represent the first direct measurement of biomolecular recognition between a single protein and any type of organic conductor, give new molecular insight into controlling cellular interactions on these polymer surfaces.
Publisher: American Chemical Society (ACS)
Date: 09-12-2019
Publisher: Elsevier BV
Date: 10-2009
DOI: 10.1016/J.BIOMATERIALS.2009.06.059
Abstract: Conducting polymers have been developed as substrates for in vitro studies with a range of cell types including electrically-excitable cells such as nerve and smooth muscle. The goal of this study was to optimise and characterise a range of polypyrrole materials to act as substrates for electrical stimulation of differentiating skeletal myoblasts. Although all of the polymer materials provided suitable substrates for myoblast adhesion and proliferation, significant differences became apparent under the low-serum conditions used for differentiation of primary myoblasts. The significance of the work lies in the design and control of polymer materials to facilitate different stages of skeletal muscle cell proliferation and/or differentiation, opening up opportunities for engineering of this tissue. This paper therefore constitutes not just a biocompatibility assessment but a comprehensive study of how synthesis conditions affect the final outcome in terms of cell response.
Publisher: Wiley
Date: 21-03-2017
Abstract: Cardiovascular diseases, including myocardial infarction, are the cause of significant morbidity and mortality globally. Tissue engineering is a key emerging treatment method for supporting and repairing the cardiac scar tissue caused by myocardial infarction. Creating cell supportive scaffolds that can be directly implanted on a myocardial infarct is an attractive solution. Hydrogels made of collagen are highly biocompatible materials that can be molded into a range of shapes suitable for cardiac patch applications. The addition of mechanically reinforcing materials, carbon nanotubes, at subtoxic levels allows for the collagen hydrogels to be strengthened, up to a toughness of 30 J m
Publisher: Elsevier BV
Date: 06-2022
Publisher: SPIE
Date: 04-2015
DOI: 10.1117/12.2084165
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3TB00463E
Publisher: Springer Science and Business Media LLC
Date: 10-01-2020
DOI: 10.1038/S41467-019-13615-2
Abstract: Label-free surface-enhanced Raman spectroscopy (SERS) can interrogate systems by directly fingerprinting their components’ unique physicochemical properties. In complex biological systems however, this can yield highly overlapping spectra that hinder s le identification. Here, we present an artificial-nose inspired SERS fingerprinting approach where spectral data is obtained as a function of sensor surface chemical functionality. Supported by molecular dynamics modeling, we show that mildly selective self-assembled monolayers can influence the strength and configuration in which analytes interact with plasmonic surfaces, ersifying the resulting SERS fingerprints. Since each sensor generates a modulated signature, the implicit value of increasing the dimensionality of datasets is shown using cell lysates for all possible combinations of up to 9 fingerprints. Reliable improvements in mean discriminatory accuracy towards 100% are achieved with each additional surface functionality. This arrayed label-free platform illustrates the wide-ranging potential of high-dimensionality artificial-nose based sensing systems for more reliable assessment of complex biological matrices.
Publisher: Wiley
Date: 29-04-2016
Abstract: The combination of stem cell therapy with a supportive scaffold is a promising approach to improving cardiac tissue engineering. Stem cell therapy can be used to repair nonfunctioning heart tissue and achieve myocardial regeneration, and scaffold materials can be utilized in order to successfully deliver and support stem cells in vivo. Current research describes passive scaffold materials here an electroactive scaffold that provides electrical, mechanical, and topographical cues to induced human pluripotent stem cells (iPS) is presented. The poly(lactic‐ co ‐glycolic acid) fiber scaffold coated with conductive polymer polypyrrole (PPy) is capable of delivering direct electrical and mechanical stimulation to the iPS. The electroactive scaffolds demonstrate no cytotoxic effects on the iPS as well as an increased expression of cardiac markers for both stimulated and unstimulated protocols. This study demonstrates the first application of PPy as a supportive electroactive material for iPS and the first development of a fiber scaffold capable of dynamic mechanical actuation.
Publisher: Wiley
Date: 25-06-2021
Abstract: The ability of an orthopedic implant to integrate successfully with the surrounding bone tissue is imperative for optimal patient outcomes. Here, the recent advances and future prospects for diamond‐based coatings of conventional osteo‐implant materials (primarily titanium) are explored. The ability of these diamond coatings to enhance integration into existing bone, improved implant mechanical properties, facilitate surface chemical functionalization, and provide anti‐microbial properties are discussed in context of orthopedic implants. These diamond‐based materials may have the additional benefit of providing an osteo‐inductive effect, enabling better integration into existing bone via stem cell recruitment and bone regeneration. Current and timely research is highlighted to support the discussion and suggestions in further improving implant integration via an osseoinductive effect from the diamond composite materials.
Publisher: Springer Science and Business Media LLC
Date: 10-07-2017
DOI: 10.1557/MRC.2017.45
Abstract: Conjugated polymers have been proposed as promising materials for scaffolds in tissue engineering applications. However, the restricted processability and biodegradability of conjugated polymers limit their use for biomedical applications. Here we synthesized a block-co-polymer of aniline tetramer and PCL (AT–PCL), and processed it into fibrous non-woven scaffolds by electrospinning. We showed that fibronectin (Fn) adhesion was dependent on the AT–PCL oxidative state, with a reduced Fn unfolding length on doped membranes. Furthermore, we demonstrated the cytocompatibility and potential of these membranes to support the growth and osteogenic differentiation of MC3T3-E1 cells over 21 days.
Publisher: Elsevier
Date: 2022
Publisher: Wiley
Date: 13-01-2022
Abstract: Stem cell fate can be directed through the application of various external physical stimuli, enabling a controlled approach to targeted differentiation. Studies involving the use of dynamic mechanical cues driven by vibrational excitation to date have, however, been limited to low frequency (Hz to kHz) forcing over extended durations (typically continuous treatment for days). Contrary to previous assertions that there is little benefit in applying frequencies beyond 1 kHz, we show here that high frequency MHz‐order mechanostimulation in the form of nanoscale litude surface reflected bulk waves are capable of triggering differentiation of human mesenchymal stem cells from various donor sources toward an osteoblast lineage, with early, short time stimuli inducing long‐term osteogenic commitment. More specifically, rapid treatments (10 min daily over 5 days) of the high frequency (10 MHz) mechanostimulation are shown to trigger significant upregulation in early osteogenic markers (RUNX2, COL1A1) and sustained increase in late markers (osteocalcin, osteopontin) through a mechanistic pathway involving piezo channel activation and Rho‐associated protein kinase signaling. Given the miniaturizability and low cost of the devices, the possibility for upscaling the platform toward practical bioreactors, to address a pressing need for more efficient stem cell differentiation technologies in the pursuit of translatable regenerative medicine strategies, is ensivaged.
Publisher: Wiley
Date: 11-10-2021
Publisher: American Chemical Society (ACS)
Date: 02-11-2012
DOI: 10.1021/JP302944N
Abstract: Phase imaging in atomic force microscopy (AFM) is a useful technique for determining dissipative tip-s le interactions related to changes in the material surface properties such as local stiffness or adhesion. In this work, we applied both phase imaging and phase spectroscopy measurements to conducting polymer (polypyrrole) doped with either hyaluronic acid or chondroitin sulfate. As observed in previous studies, phase-separated regions correlating with the characteristic nodular topography of polypyrrole and attributed to crystalline (doped) and amorphous (undoped) regions were observed. However, through additional phase spectroscopy measurements, we show that the phase-separated regions can arise due to variation in attractive and repulsive tip-s le interactions across the polymer surface. We show that these attractive and repulsive interactions are dependent on the redox state and degree of doping and suggest that they are related to phase separation of the polymer surface charge and/or energy. The latter may have implications for these materials when under investigation in a fluid, or biological, environment. For ex le, such surface variations will play a role in electrostatic forces, which in turn can influence protein and cellular interactions.
Publisher: Elsevier BV
Date: 06-2019
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6RA11682E
Abstract: The characterisation of biomaterials for cardiac tissue engineering applications is vital for the development of effective treatments for the repair of cardiac function.
Publisher: Elsevier BV
Date: 03-2010
DOI: 10.1016/J.BIOMATERIALS.2009.11.040
Abstract: Conducting polymers doped with biomolecules (biodopants) are becoming more widely evaluated for use as biomaterials. The use of biodopants is intended to enhance the compatibility of the polymers, however their effect on the physical properties of the final composite material has generally been less of a consideration. Here, we have characterised the physical surface properties of polypyrrole substrates doped with extracellular matrix and non-biological molecules using Atomic Force Microscopy (AFM) and Electrochemical AFM (EC-AFM) techniques. The physical parameters of the differently doped films ranged between 5 and 32 nm for the RMS roughness, 30-1000 MPa for the Young's modulus, and 1.6-4.7% for the actuation strain. It was found that irrespective of whether the dopant was biologically derived, the physical properties tended to group together with films having either a low roughness, low modulus and high strain, or vice versa. When compared to our previous study, which investigated these polymers as potential biomaterials for supporting the growth and differentiation of skeletal muscle cells, these two groupings of the parameters correlated with the differing ability of the polypyrrole substrates to support the cells. Thus, in addition to the chemical advantage gained from using biodopants, the resulting physical properties of the polymer material should also be considered in their design as biomaterials for tissue engineering applications.
Publisher: American Chemical Society (ACS)
Date: 20-11-2020
Publisher: American Chemical Society (ACS)
Date: 15-02-2021
Publisher: Elsevier BV
Date: 2023
Publisher: American Chemical Society (ACS)
Date: 13-07-2022
Publisher: American Chemical Society (ACS)
Date: 30-08-2021
Publisher: Wiley
Date: 14-09-2012
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D2CS00830K
Abstract: Neural recording, stimulation, and biochemical sensing using semiconducting electrodes in both electrical and optical domains are discussed. Their differences from metallic electrodes from the application and characterization perspective are highlighted.
Location: United Kingdom of Great Britain and Northern Ireland
Start Date: 2020
End Date: 2022
Funder: Australian Research Council
View Funded ActivityStart Date: 2020
End Date: 12-2024
Amount: $401,000.00
Funder: Australian Research Council
View Funded Activity