Publications by authors named "Simon E Moulton"

62 Publications

Potential Pulse-Facilitated Active Adsorption of Lubricin Polymer Brushes Can Both Accelerate Self-Assembly and Control Grafting Density.

Langmuir 2021 Sep 10. Epub 2021 Sep 10.

ARC Centre of Excellence for Electromaterials Science, Faculty of Science, Engineering and Technology, Swinburne University of Technology, John Street, Hawthorn, Melbourne/Victoria 3122, Australia.

Self-assembled lubricin (LUB) monolayers are an effective antiadhesive coating for biomedical applications. Long deposition times and limited control over the monolayer grafting density remain impediments to commercialization and applications in advanced sensor technologies. This work describes a novel potential pulse-facilitated coating method that reduces coating times to mere seconds while also providing high-level control over the achieved grafting density. This is the first time that the potential pulse-facilitated method is applied for direct assembling of a large and complex polyelectrolyte.
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http://dx.doi.org/10.1021/acs.langmuir.1c02263DOI Listing
September 2021

Microencapsulation of growth factors by microfluidic system.

MethodsX 2021 28;8:101324. Epub 2021 Mar 28.

ARC Centre of Excellence for Electromaterials Science, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Victoria 3122, Australia.

The encapsulation of growth factors is an important component of tissue engineer- ing. Using microspheres is a convenient approach in which the dose of factors can be regulated by increasing or decreasing the number of encapsulated microspheres. Moreover, microspheres offer the possibility of delivering the growth factors directly to the target site. However, the fabrication of microspheres by traditional emulsion methods is largely variable due to the experimental procedure. We have developed a protocol using a commercially available microfluidic system that allows formation of tunable particle-size droplets loaded with growth factors. The methodology includes a guide for preparing an alginate-growth factors solution followed by the specific set-up needed for using the microfluidic system to form the microspheres. The pro- cedure also includes a unique post-crosslinking process without pH modification. These methods allow the preservation of integrity and bioactivity of the growth factors tested (BMP-6 and TGF -3) and their subsequent sustained delivery.•The protocol can be tuned to form particles of various sizes.•The gentle post-crosslinking process allows conformational integrity of various bioactive molecules.
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http://dx.doi.org/10.1016/j.mex.2021.101324DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8374335PMC
March 2021

Towards bioengineered skeletal muscle: recent developments in vitro and in vivo.

Essays Biochem 2021 Aug;65(3):555-567

Biomedical and Electrical Engineering, School of Engineering, RMIT University, Melbourne, VIC 3000, Australia.

Skeletal muscle is a functional tissue that accounts for approximately 40% of the human body mass. It has remarkable regenerative potential, however, trauma and volumetric muscle loss, progressive disease and aging can lead to significant muscle loss that the body cannot recover from. Clinical approaches to address this range from free-flap transfer for traumatic events involving volumetric muscle loss, to myoblast transplantation and gene therapy to replace muscle loss due to sarcopenia and hereditary neuromuscular disorders, however, these interventions are often inadequate. The adoption of engineering paradigms, in particular materials engineering and materials/tissue interfacing in biology and medicine, has given rise to the rapidly growing, multidisciplinary field of bioengineering. These methods have facilitated the development of new biomaterials that sustain cell growth and differentiation based on bionic biomimicry in naturally occurring and synthetic hydrogels and polymers, as well as additive fabrication methods to generate scaffolds that go some way to replicate the structural features of skeletal muscle. Recent advances in biofabrication techniques have resulted in significant improvements to some of these techniques and have also offered promising alternatives for the engineering of living muscle constructs ex vivo to address the loss of significant areas of muscle. This review highlights current research in this area and discusses the next steps required towards making muscle biofabrication a clinical reality.
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http://dx.doi.org/10.1042/EBC20200149DOI Listing
August 2021

Near-infrared light-responsive liposomes for protein delivery: Towards bleeding-free photothermally-assisted thrombolysis.

J Control Release 2021 Sep 18;337:212-223. Epub 2021 Jul 18.

Atherothrombosis and Vascular Biology Laboratory, Baker Heart and Diabetes Institute, Melbourne, VIC 3004, Australia; Department of Medicine, Monash University, Melbourne, VIC 3800, Australia; Department of Cardiology, Alfred Hospital, Melbourne, VIC 3004, Australia; Department of Cardiometabolic Health, University of Melbourne, VIC 3010, Australia. Electronic address:

Smart drug delivery systems represent state-of-the-art approaches for targeted therapy of life-threatening diseases such as cancer and cardiovascular diseases. Stimuli-responsive on-demand release of therapeutic agents at the diseased site can significantly limit serious adverse effects. In this study, we engineered a near-infrared (NIR) light-responsive liposomal gold nanorod-containing platform for on-demand delivery of proteins using a hybrid formulation of ultrasmall gold nanorods (AuNRs), thermosensitive phospholipid (DPPC) and non-ionic surfactant (Brij58). In light-triggered release optimization studies, 55.6% (± 4.8) of a FITC-labelled model protein, ovalbumin (MW 45 kDa) was released in 15 min upon NIR irradiation (785 nm, 1.35 W/cm for 5 min). This platform was then utilized to test on-demand delivery of urokinase-plasminogen activator (uPA) for bleeding-free photothermally-assisted thrombolysis, where the photothermal effect of AuNRs would synergize with the released uPA in clot lysis. Urokinase light-responsive liposomes showed 80.7% (± 4.5) lysis of an in vitro halo-clot model in 30 min following NIR irradiation (785 nm, 1.35 W/cm for 5 min) compared to 36.3% (± 4.4) and 15.5% (± 5.5) clot lysis from equivalent free uPA and non-irradiated liposomes respectively. These results show the potential of low-dose, site-specific thrombolysis via the combination of light-triggered delivery/release of uPA from liposomes combined with photothermal thrombolytic effects from gold nanorods. In conclusion, newly engineered, gold nanorod-based, NIR light-responsive liposomes represent a promising drug delivery system for site-directed, photothermally-stimulated therapeutic protein release.
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http://dx.doi.org/10.1016/j.jconrel.2021.07.024DOI Listing
September 2021

Cellular Interactions with Lubricin and Hyaluronic Acid-Lubricin Composite Coatings on Gold Electrodes in Passive and Electrically Stimulated Environments.

ACS Biomater Sci Eng 2021 08 20;7(8):3696-3708. Epub 2021 Jul 20.

Institute for Frontier Materials and ARC Centre of Excellence for Electromaterials Science, Deakin University, Melbourne, VIC 3216, Australia.

In the field of bionics, the long-term effectiveness of implantable bionic interfaces depends upon maintaining a "clean" and unfouled electrical interface with biological tissues. Lubricin (LUB) is an innately biocompatible glycoprotein with impressive antifouling properties. Unlike traditional antiadhesive coatings, LUB coatings do not passivate electrode surfaces, giving LUB coatings great potential for controlling surface fouling of implantable electrode interfaces. This study characterizes the antifouling properties of bovine native LUB (N-LUB), recombinant human LUB (R-LUB), hyaluronic acid (HA), and composite coatings of HA and R-LUB (HA/R-LUB) on gold electrodes against human primary fibroblasts and chondrocytes in passive and electrically stimulated environments for up to 96 h. R-LUB coatings demonstrated highly effective antifouling properties, preventing nearly all adhesion and proliferation of fibroblasts and chondrocytes even under biphasic electrical stimulation. N-LUB coatings, while showing efficacy in the short term, failed to produce sustained antifouling properties against fibroblasts or chondrocytes over longer periods of time. HA/R-LUB composite films also demonstrated highly effective antifouling performance equal to the R-LUB coatings in both passive and electrically stimulated environments. The high electrochemical stability and long-lasting antifouling properties of R-LUB and HA/R-LUB coatings in electrically stimulating environments reveal the potential of these coatings for controlling unwanted cell adhesion in implantable bionic applications.
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http://dx.doi.org/10.1021/acsbiomaterials.1c00479DOI Listing
August 2021

Photothermal release and recovery of mesenchymal stem cells from substrates functionalized with gold nanorods.

Acta Biomater 2021 07 16;129:110-121. Epub 2021 May 16.

ARC Training Centre in Biodevices, Faculty of Science Engineering and Technology, Swinburne University of Technology, Hawthorn, Victoria 3122 Australia; Department of Chemistry and Physics, La Trobe Insitute for Molecular Science, La Trobe University, Bundoora 3083, Australia. Electronic address:

Mesenchymal stem cell therapies show great promise in regenerative medicine. However, to generate clinically relevant numbers of these stem cells, significant in vitro expansion of the cells is required before transplantation into the affected wound or defect. The current gold standard protocol for recovering in vitro cultured cells involves treatment with enzymes such as trypsin which can affect the cell phenotype and ability to interact with the environment. Alternative enzyme free methods of adherent cell recovery have been investigated, but none match the convenience and performance of enzymatic detachment. In this work we have developed a synthetically simple, low cost cell culture substrate functionalized with gold nanorods that can support cell proliferation and detachment. When these nanorods are irradiated with biocompatible low intensity near infrared radiation (785 nm, 560 mWcm) they generate localized surface plasmon resonance induced nanoscale heating effects which trigger detachment of adherent mesenchymal stem cells. Through simulations and thermometry experiments we show that this localized heating is concentrated at the cell-nanorod interface, and that the stem cells detached using this technique show either similar or improved multipotency, viability and ability to differentiate into clinically desirable osteo and adipocytes, compared to enzymatically harvested cells. This proof-of-principle work shows that photothermally mediated cell detachment is a promising method for recovering mesenchymal stem cells from in vitro culture substrates, and paves the way for further studies to scale up this process and facilitate its clinical translation. STATEMENT OF SIGNIFICANCE: New non-enzymatic methods of harvesting adherent cells without damaging or killing them are highly desirable in fields such as regenerative medicine. Here, we present a synthetically simple, non-toxic, infra-red induced method of harvesting mesenchymal stem cells from gold nanorod functionalized substrates. The detached cells retain their ability to differentiate into therapeutically valuable osteo and adipocytes. This work represents a significant improvement on similar cell harvesting studies due to: its simplicity; the use of clinically valuable stem cells as oppose to immortalized cell lines; and the extensive cellular characterization performed. Understanding, not just if cells live or die but how they proliferate and differentiate after photothermal detachment will be essential for the translation of this and similar techniques into commercial devices.
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http://dx.doi.org/10.1016/j.actbio.2021.05.008DOI Listing
July 2021

Enhanced Electroactivity, Mechanical Properties, and Printability through the Addition of Graphene Oxide to Photo-Cross-linkable Gelatin Methacryloyl Hydrogel.

ACS Biomater Sci Eng 2021 06 6;7(6):2279-2295. Epub 2021 May 6.

ARC Centre of Excellence for Electromaterials Science, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Melbourne, Victoria 3122, Australia.

The human tissues most sensitive to electrical activity such as neural and muscle tissues are relatively soft, and yet traditional conductive materials used to interface with them are typically stiffer by many orders of magnitude. Overcoming this mismatch, by creating both very soft and electroactive materials, is a major challenge in bioelectronics and biomaterials science. One strategy is to imbue soft materials, such as hydrogels, with electroactive properties by adding small amounts of highly conductive nanomaterials. However, electroactive hydrogels reported to date have required relatively large volume fractions (>1%) of added nanomaterial, have shown only modest electroactivity, and have not been processable via additive manufacturing to create 3D architectures. Here, we describe the development and characterization of improved biocompatible photo-cross-linkable soft hybrid electroactive hydrogels based on gelatin methacryloyol (GelMA) and large area graphene oxide (GO) flakes, which resolve each of these three limitations. The addition of very small amounts (less than a 0.07% volume fraction) of GO to a 5% w/v GelMA hydrogel resulted in a dramatic (∼35-fold) decrease in the impedance at 1 Hz compared with GelMA alone. The GelMA/GO coated indium tin oxide (ITO) electrode also showed a considerable reduction in the impedance at 1 kHz (down to 170 Ω compared with 340 Ω for the GelMA-coated ITO), while charge injection capacity increased more than 6-fold. We attribute this enhanced electroactivity to the increased electroactive surface area contributed by the GO. Despite this dramatic change in electroactivity, the GelMA/GO composite hydrogels' mechanical properties were only moderately affected. Mechanical properties increased by ∼2-fold, and therefore, the hydrogels' desired softness of <4 kPa was retained. Also, we demonstrate how light attenuation through the gel can be used to create a stiffness gradient with the exposed surface of the gel having an elastic modulus of <1.5 kPa. GO addition also enhanced the rheological properties of the GelMA composites, thus facilitating 3D extrusion printing. GelMA/GO enhanced filament formation as well as improved printability and the shape fidelity/integrity of 3D printed structures compared with GelMA alone. Additionally, the GelMA/GO 3D printed structures presented a higher electroactive behavior than nonprinted samples containing the same GelMA/GO amount, which can be attributed to the higher electroactive surface area of 3D printed structures. These findings provide new rational choices of electroactive hydrogel (EAH) compositions with broad potential applications in bioelectronics, tissue engineering, and drug delivery.
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http://dx.doi.org/10.1021/acsbiomaterials.0c01734DOI Listing
June 2021

Antifouling Strategies for Electrochemical Biosensing: Mechanisms and Performance toward Point of Care Based Diagnostic Applications.

ACS Sens 2021 04 25;6(4):1482-1507. Epub 2021 Mar 25.

ARC Centre of Excellence for Electromaterials Science, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Melbourne, Victoria 3122, Australia.

Although there exist numerous established laboratory-based technologies for sample diagnostics and analyte detection, many medical and forensic science applications require point of care based platforms for rapid on-the-spot sample analysis. Electrochemical biosensors provide a promising avenue for such applications due to the portability and functional simplicity of the technology. However, the ability to develop such platforms with the high sensitivity and selectivity required for analysis of low analyte concentrations in complex biological samples remains a paramount issue in the field of biosensing. Nonspecific adsorption, or fouling, at the electrode interface via the innumerable biomolecules present in these sample types (i.e., serum, urine, blood/plasma, and saliva) can drastically obstruct electrochemical performance, increasing background "noise" and diminishing both the electrochemical signal magnitude and specificity of the biosensor. Consequently, this review aims to discuss strategies and concepts used throughout the literature to prevent electrode surface fouling in biosensors and to communicate the nature of the antifouling mechanisms by which they operate. Evaluation of each antifouling strategy is focused primarily on the fabrication method, experimental technique, sample composition, and electrochemical performance of each technology highlighting the overall feasibility of the platform for point of care based diagnostic/detection applications.
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http://dx.doi.org/10.1021/acssensors.1c00390DOI Listing
April 2021

Lubricin as a tool for controlling adhesion in vivo and ex vivo.

Biointerphases 2021 03 18;16(2):020802. Epub 2021 Mar 18.

The Aikenhead Centre for Medical Discovery (ACMD), St Vincent's Hospital Melbourne, Melbourne, Victoria 3065, Australia.

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.
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http://dx.doi.org/10.1116/6.0000779DOI Listing
March 2021

Formation of alginate microspheres prepared by optimized microfluidics parameters for high encapsulation of bioactive molecules.

J Colloid Interface Sci 2021 Apr 13;587:240-251. Epub 2020 Dec 13.

ARC Centre of Excellence for Electromaterials Science, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Victoria 3122, Australia; BioFab3D, Aikenhead Centre for Medical Discovery, St Vincent's Hospital, Melbourne, Australia; Iverson Health Innovation Research Institute, Swinburne University of Technology, Hawthorn, Australia. Electronic address:

Drug delivery systems such as microspheres have shown potential in releasing biologicals effectively for tissue engineering applications. Microfluidic systems are especially attractive for generating microspheres as they produce microspheres of controlled-size and in low volumes, using micro-emulsion processes. However, the flow rate dependency on the encapsulation of molecules at a microscale is poorly understood. In particular, the flow rate and pressure parameters might influence the droplet formation and drug encapsulation efficiency. We evaluated the parameters within a two-reagent flow focusing microfluidic chip under continuous formation of hydrogel particles using a flourinated oil and an ionic crosslinkable alginate hydrogel. Fluorescein isothiocyanate-dextran sulfate (FITC-dextran sulfate MW: 40 kDa) was used to evaluate the variation of the encapsulation efficiency with the flow parameters, optimizing droplets and microsphere formation. The ideal flow rates allowing for maximum encapsulation efficiency, were utilised to form bioactive microspheres by delivering transforming growth factor beta-3 (TGFβ-3) in cell culture media. Finally, we evaluated the potential of microfluidic-formed microspheres to be included within biological environments. The biocompatibility of the microspheres was tested over 28 days using adult human mesenchymal stem cells (hMSCs). The release profile of the growth factors from microspheres showed a sustained release in media, after an initial burst, up to 30 days. The metabolic activity of the cells cultured in the presence of the microspheres was similar to controls, supporting the biocompatibility of this approach. The fine-tuned parameters for alginate hydrogel to form microspheres have potential in encapsulating and preserving functional structure of bioactive agents for future tissue engineering applications.
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http://dx.doi.org/10.1016/j.jcis.2020.12.026DOI Listing
April 2021

Dual Delivery of Gemcitabine and Paclitaxel by Wet-Spun Coaxial Fibers Induces Pancreatic Ductal Adenocarcinoma Cell Death, Reduces Tumor Volume, and Sensitizes Cells to Radiation.

Adv Healthc Mater 2020 11 1;9(21):e2001115. Epub 2020 Oct 1.

School of Chemistry and Molecular Bioscience, Molecular Horizons, University of Wollongong, Wollongong, NSW, 2522, Australia.

Pancreatic ductal adenocarcinoma (PDAC) has a dismal prognosis, with surgical resection of the tumor in conjunction with systemic chemotherapy the only potential curative therapy. Up to 80% of diagnosed cases are deemed unresectable, prompting the need for alternative treatment approaches. Herein, coaxial polymeric fibers loaded with two chemotherapeutic agents, gemcitabine (Gem) and paclitaxel (Ptx), are fabricated to investigate the effect of local drug delivery on PDAC cell growth in vitro and in vivo. A wet-spinning fabrication method to form a coaxial fiber with a polycaprolactone shell and alginate core loaded with Ptx and Gem, respectively, is used. In vitro, Gem+Ptx fibers display significant cytotoxicity as well as radiosensitizing properties toward PDAC cell lines greater than the equivalent free drugs, which may be attributed to a radiosensitizing effect of the polymers. In vivo studies assessing Gem+Ptx fiber efficacy found that Gem+Ptx fibers reduce tumor volume in a xenograft mouse model of PDAC. Importantly, no difference in mouse weight, circulating cytokines, or liver function is observed in mice treated with Gem+Ptx fibers compared to the empty fiber controls confirming the safety of the implant approach. With further development, Gem+Ptx fibers can improve the treatment of unresectable PDAC in the future.
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http://dx.doi.org/10.1002/adhm.202001115DOI Listing
November 2020

High Energy Density Heteroatom (O, N and S) Enriched Activated Carbon for Rational Design of Symmetric Supercapacitors.

Chemistry 2021 Jan 26;27(2):669-682. Epub 2020 Nov 26.

Department of Printed Electronics Engineering, Sunchon National University, 255, Jungang-ro, Suncheon-si, Jellanamdo, 57922, Republic of Korea.

Carbon-based symmetric supercapacitors (SCs) are known for their high power density and long cyclability, making them an ideal candidate for power sources in new-generation electronic devices. To boost their electrochemical performances, deriving activated carbon doped with heteroatoms such as N, O, and S are highly desirable for increasing the specific capacitance. In this regard, activated carbon (AC) self-doped with heteroatoms is directly derived from bio-waste (lima-bean shell) using different KOH activation processes. The heteroatom-enriched AC synthesized using a pretreated carbon-to-KOH ratio of 1:2 ([email protected]) shows excellent surface morphology with a large surface area of 1508 m  g . As an SC electrode material, the presence of heteroatoms (N and S) reduces the interfacial charge-transfer resistance and increases the ion-accessible surface area, which inherently provides additional pseudocapacitance. The [email protected] electrode attains a maximum specific capacitance (C ) of 342 F g at a specific current of 1 Ag in 1 m NaClO electrolyte at the wide potential window of 1.8 V. Moreover, as symmetric SCs the [email protected] electrode delivers a maximum specific capacitance (C ) of 191 F g with a maximum specific energy of 21.48 Wh kg and high specific power of 14 000 W kg and excellent retention of its initial capacitance (98 %) even after 10000 charge/discharge cycles. In addition, a flexible supercapacitor fabricated utilizing [email protected] electrodes and a LiCl/polyvinyl alcohol (PVA)-based polymer electrolyte shows a maximum C of 119 F g with considerable specific energy and power.
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http://dx.doi.org/10.1002/chem.202003253DOI Listing
January 2021

Wet-Spun Trojan Horse Cell Constructs for Engineering Muscle.

Front Chem 2020 20;8:18. Epub 2020 Feb 20.

ARC Centre for Electromaterials Science, Intelligent Polymer Research Institute, University of Wollongong, Fairy Meadow, NSW, Australia.

Engineering of 3D regenerative skeletal muscle tissue constructs (skMTCs) using hydrogels containing muscle precursor cells (MPCs) is of potential benefit for repairing Volumetric Muscle Loss (VML) arising from trauma (e.g., road/industrial accident, war injury) or for restoration of functional muscle mass in disease (e.g., Muscular Dystrophy, muscle atrophy). Additive Biofabrication (AdBiofab) technologies make possible fabrication of 3D regenerative skMTCs that can be tailored to specific delivery requirements of VML or functional muscle restoration. Whilst 3D printing is useful for printing constructs of many tissue types, the necessity of a balanced compromise between cell type, required construct size and material/fabrication process cyto-compatibility can make the choice of 3D printing a secondary alternative to other biofabrication methods such as wet-spinning. Alternatively, wet-spinning is more amenable to formation of fibers rather than (small) layered 3D-Printed constructs. This study describes the fabrication of biosynthetic alginate fibers containing MPCs and their use for delivery of dystrophin-expressing cells to dystrophic muscle in the mouse model of Duchenne Muscular Dystrophy (DMD) compared to poly(DL-lactic-co-glycolic acid) copolymer (PLA:PLGA) topically-seeded with myoblasts. In addition, this study introduces a novel method by which to create 3D layered wet-spun alginate skMTCs for bulk mass delivery of MPCs to VML lesions. As such, this work introduces the concept of "Trojan Horse" Fiber MTCs (TH-fMTCs) and 3d Mesh-MTCs (TH-mMTCs) for delivery of regenerative MPCs to diseased and damaged muscle, respectively.
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http://dx.doi.org/10.3389/fchem.2020.00018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7044405PMC
February 2020

Tuning drug dosing through matching optically active polymer composition and NIR stimulation parameters.

Int J Pharm 2020 Feb 17;575:118976. Epub 2019 Dec 17.

ARC Centre of Excellence for Electromaterials Science, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, VIC 3122, Australia; Iverson Health Innovation Research Institute, Swinburne University of Technology, Hawthorn, VIC 3122, Australia. Electronic address:

Controlled release is at the forefront of modern bioscience as it aims to address challenges associated with the dosing of drugs within required levels for therapeutic effect. Many materials and approaches can be used to control the release from different reservoirs including nanoparticles, liposomes and hydrogels. Using thermoresponsive hydrogels, near infrared illumination of plasmonic nanoparticles can be used to control the hydrogel through localised surface plasmon resonance heating. This work extends beyond a material level and pursues detailed examination of the drug release characteristics of a variable acrylic acid poly(N-isopropylacrylamide) coated gold nanorod system using dexamethasone as a model drug. Release was examined under different irradiation power densities and exposure times. Bulk heating effects in all stimulation protocols did not exceed the lower critical solution temperature of the system, but a marked increase in release was seen following stimulation. This was likely due to more intense heating occurring around the nanorods. A release model was established to describe the amount of drug eluted relative to input energy, suggesting that shorter irradiation periods release the drug more efficiently. The data reported establishes plasmonically modulated thermosensitive hydrogels as a candidate material that can be tailored to specific clinical applications of stimulated release.
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http://dx.doi.org/10.1016/j.ijpharm.2019.118976DOI Listing
February 2020

Adhesion and Self-Assembly of Lubricin (PRG4) Brush Layers on Different Substrate Surfaces.

Langmuir 2019 12 7;35(48):15834-15848. Epub 2019 Aug 7.

Institute for Frontier Materials and ARC Centre of Excellence for Electromaterials Science , Deakin University , Melbourne , Victoria 3216 , Australia.

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 diverse 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.
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http://dx.doi.org/10.1021/acs.langmuir.9b01809DOI Listing
December 2019

Growth factor delivery: Defining the next generation platforms for tissue engineering.

J Control Release 2019 07 28;306:40-58. Epub 2019 May 28.

ARC Centre of Excellence for Electromaterials Science, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia; [email protected], St Vincent's Hospital Melbourne, Fitzroy, Victoria 3065, Australia; Iverson Health Innovation Research Institute, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia. Electronic address:

Growth factors play a crucial role in tissue engineering by directing the fate of cells and allowing the formation of tissues. Understanding the key requirements for growth factor delivery can point the way towards novel tissue engineering platforms. Growth factor suffer from a tendency to lose their bioactivity upon environmental and physical changes. The need for biomaterials that can preserve the native form of growth factor has directed interest towards hydrogels (e.g. gelatin, alginate) and hydrophobic polymers (e.g. polycaprolactone). In recent advances, the use of composite materials such as PCL-chitosan (hydrogel-hydrophobic polymer) and gelatin-alginate (hydrogel-hydrogel polymers) has opened the possibility of fine tuning the delivery systems. Other current research is exploring new delivery strategies for growth factors such as the use of bioreactors and delivery by molecule-recognition. In particular, systems that allow the delivery of growth factors in a 3-dimensional manner are promising compared to conventional methods. This review analyses the biological considerations, material selection, and delivery strategies that have been established as the pivotal components for growth factor delivery and will support the next generation of tissue engineering platforms by providing a comprehensive landscape for the growth factor delivery field. The last part of the review discusses the current challenges and promising future directions for delivering growth factors.
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http://dx.doi.org/10.1016/j.jconrel.2019.05.028DOI Listing
July 2019

Controlled release from PCL-alginate microspheres via secondary encapsulation using GelMA/HAMA hydrogel scaffolds.

Soft Matter 2019 May;15(18):3779-3787

ARC Centre of Excellence for Electromaterials Science, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Melbourne, 3122, Australia.

Controlling the release of bioactive agents has important potential applications in tissue engineering. While microspheres have been investigated to manipulate release rates, the majority of these investigations have been based on delivery into aqueous media, whereas the cellular environment in tissue engineering is more typically a hydrogel scaffold. If drug-loaded microspheres are introduced within scaffolds to deliver biologically active substances in situ, it is crucial to understand how the release rate is influenced by interactions between the microspheres and the scaffold. Here, we report the fabrication and characterization of a biodegradable scaffold that contains composite microspheres and is suitable for biological applications. Our approach evaluates the influence on the release profile of a model drug (FITC-dextran sulfate) from alginate and PCL-alginate microspheres within a hydrogel construct forming a secondary encapsulation. Increasing the degree of crosslinking in the secondary encapsulation matrix led to a slower cumulative release from 36% to 15%, from the alginate microspheres, whereas a decrease from 26% to 6% was observed for the PCL-alginate microspheres. These results suggest that the release of bioactive molecules can be fine tuned by independently engineering the properties of the scaffold and microspheres.
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http://dx.doi.org/10.1039/c8sm02575dDOI Listing
May 2019

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

Adv Healthc Mater 2019 05 6;8(9):e1801321. Epub 2019 Mar 6.

ARC Centre of Excellence for Electromaterials Science, Faculty of Science, Engineering and Technology, Swinburne University of Technology, John St, Hawthorn, VIC, 3122, Australia.

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.
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http://dx.doi.org/10.1002/adhm.201801321DOI Listing
May 2019

A simple technique for development of fibres with programmable microsphere concentration gradients for local protein delivery.

J Mater Chem B 2019 01 2;7(4):556-565. Epub 2019 Jan 2.

Intelligent Polymer Research Institute, ARC Centre of Excellence for Electromaterials Science, AIIM Facility, Innovation Campus, University of Wollongong, Wollongong, NSW 2522, Australia.

Alginate has been a biologically viable option for controlled local delivery of bioactive molecules in vitro and in vivo. Specific bioactive molecule release profiles are achieved often by controlling polymer composition/concentration, which also determines the modulus of hydrogels. This largely limits alginate-mediated bioactive molecule delivery to single-factors of uniform concentration applications, rather than applications that may require (multiple) bioactive molecules delivered at a concentration gradient for chemotactic purposes. Here we report a two-phase PLGA/alginate delivery system composed of protein-laden poly-d,l-lactic-co-glycolic acid (PLGA) microspheres wet-spun into alginate fibres. Fluorescein isothiocyanate-conjugated bovine serum albumin (FITC-BSA) was used as a model protein and the developed structures were characterized. The fabrication system devised was shown to produce wet-spun fibres with a protein concentration gradient (G-Alg/PLGA fibre). The two-phase delivery matrices display retarded FITC-BSA release in both initial and late stages compared to release from the PLGA microspheres or alginate fibre alone. In addition, incorporation of higher concentrations of protein-loaded PLGA microspheres increased protein release compared to the fibres with lower concentrations of BSA-loaded microspheres. The "programmable" microsphere concentration gradient fibre methodology presented here may enable development of novel alginate scaffolds with the ability to guide tissue regeneration through tightly-controlled release of one or more proteins in highly defined spatio-temporal configurations.
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http://dx.doi.org/10.1039/c8tb01504jDOI Listing
January 2019

Debundling, Dispersion, and Stability of Multiwalled Carbon Nanotubes Driven by Molecularly Designed Electron Acceptors.

Langmuir 2018 10 28;34(40):12137-12144. Epub 2018 Sep 28.

Carbon nanotubes (CNTs) have attracted significant attention because of their outstanding physical and chemical properties, and yet, their high natural tendency to form bundles, ropes, or aggregates, as a consequence of their strong π-π interactions, limits their solvent processing and further applications. Efficient processing solvents, mostly amide-based, that partially compensate for these strong inter-CNT π-π interactions have been widely reported. However, the yield of debundled/dispersed CNTs and the stability of subsequent dispersions in these solvents remain key challenges. Moreover, there are major concerns related to the large-scale use of conventional solvents, as they are fossil fuel based and intrinsically highly toxic, hence the need to identify environmentally friendly and safer alternatives. Herein, we address these challenges by using a ternary system composed of multiwalled CNTs (MWCNTs), tailored electron-deficient acceptors, and an organic solvent. Not only do the electron-deficient acceptors interrupt the inter-CNTs π-π interactions, thereby enabling the subsequent debundling and dispersion of MWCNTs aggregates in the solvent, they also act as stabilizers, after dispersion, by inhibiting inter-CNT π-π interactions and re-agglomeration. The use of electron acceptors increases the yield by a factor of 165 in N-methyl 2-pyrrolidone, improves the long-term stability of the debundled and dispersed MWCNTs, and reduces the energy input to only 30 min of mild bath sonication, compared with prolonged high-energy sonication reported in the literature. We also report for the first time, the use in MWCNT processing of a "green" biosolvent, dihydrolevoglucosenone, as an environmentally friendly and nontoxic alternative to the more conventional amide-based solvents.
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http://dx.doi.org/10.1021/acs.langmuir.8b02878DOI Listing
October 2018

Photoswitchable Layer-by-Layer Coatings Based on Photochromic Polynorbornenes Bearing Spiropyran Side Groups.

Langmuir 2018 04 30;34(14):4210-4216. Epub 2018 Mar 30.

Insight Centre for Data Analytics, National Centre for Sensor Research, School of Chemical Sciences , Dublin City University , Dublin 9 , Ireland.

Herein, we present the synthesis of linear photochromic norbornene polymers bearing spiropyran side groups (poly(SP-R)) and their assembly into layer-by-layer (LbL) films on glass substrates when converted to poly(MC-R) under UV irradiation. The LbL films were composed of bilayers of poly(allylamine hydrochloride) (PAH) and poly(MC-R), forming (PAH/poly(MC-R)) coatings. The merocyanine (MC) form presents a significant absorption band in the visible spectral region, which allowed tracking of the LbL deposition process by UV-vis spectroscopy, which showed a linear increase of the characteristic MC absorbance band with increasing number of bilayers. The thickness and morphology of the (PAH/poly(MC-R)) films were characterized by ellipsometry and scanning electron microscopy, respectively, with a height of ∼27.5 nm for the first bilayer and an overall height of ∼165 nm for the (PAH/poly(MC-R)) multilayer film. Prolonged white light irradiation (22 h) resulted in a gradual decrease of the MC band by 90.4 ± 2.9% relative to the baseline, indicating the potential application of these films as coatings for photocontrolled delivery systems.
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http://dx.doi.org/10.1021/acs.langmuir.8b00137DOI Listing
April 2018

Electrochemical Behavior and Redox-Dependent Disassembly of Gallic Acid/Fe Metal-Phenolic Networks.

ACS Appl Mater Interfaces 2018 Feb 30;10(6):5828-5834. Epub 2018 Jan 30.

ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, and the Department of Chemical Engineering, The University of Melbourne , Parkville, Victoria 3010, Australia.

Metal-phenolic networks (MPNs) are a versatile class of organic-inorganic hybrid systems that are generating interest for applications in catalysis, bioimaging, and drug delivery. These self-assembled MPNs possess metal-coordinated structures and may potentially serve as redox-responsive platforms for triggered disassembly or drug release. Therefore, a comprehensive study of the reduction and oxidation behavior of MPNs for evaluating their redox responsiveness, specific conditions required for their disassembly, and the kinetics of metal ion release, is necessary. Using a representative MPN gallic acid-iron (GA/Fe) system, we conducted electrochemical studies to provide fundamental insights into the redox behavior of these MPNs. We demonstrate that GA/Fe is redox active, and evaluate its electrochemical reversibility, identify the oxidation state of the redox-active species, and provide information regarding the stability of the networks toward reductive stimuli and specific redox conditions required for the "on-off" or continuous release of Fe. Overall, through studying the redox properties of GA/Fe films, we advance the understanding of multifunctional iron-containing MPN platforms that may have practical significance for biologically relevant applications.
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http://dx.doi.org/10.1021/acsami.7b19322DOI Listing
February 2018

Conductive Tough Hydrogel for Bioapplications.

Macromol Biosci 2018 02 13;18(2). Epub 2017 Dec 13.

ARC Centre of Excellence for Electromaterials Science, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, Victoria, 3122, Australia.

Biocompatible conductive tough hydrogels represent a new class of advanced materials combining the properties of tough hydrogels and biocompatible conductors. Here, a simple method, to achieve a self-assembled tough elastomeric composite structure that is biocompatible, conductive, and with high flexibility, is reported. The hydrogel comprises polyether-based liner polyurethane (PU), poly(3,4-ethylenedioxythiophene) (PEDOT) doped with poly(4-styrenesulfonate) (PSS), and liquid crystal graphene oxide (LCGO). The polyurethane hybrid composite (PUHC) containing the PEDOT:PSS, LCGO, and PU has a higher electrical conductivity (10×), tensile modulus (>1.6×), and yield strength (>1.56×) compared to respective control samples. Furthermore, the PUHC is biocompatible and can support human neural stem cell (NSC) growth and differentiation to neurons and supporting neuroglia. Moreover, the stimulation of PUHC enhances NSC differentiation with enhanced neuritogenesis compared to unstimulated cultures. A model describing the synergistic effects of the PUHC components and their influence on the uniformity, biocompatibility, and electromechanical properties of the hydrogel is presented.
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http://dx.doi.org/10.1002/mabi.201700270DOI Listing
February 2018

Structural Analysis and Protein Functionalization of Electroconductive Polypyrrole Films Modified by Plasma Immersion Ion Implantation.

ACS Biomater Sci Eng 2017 Oct 30;3(10):2247-2258. Epub 2017 Aug 30.

Applied and Plasma Physics, School of Physics, University of Sydney, A28 Physics Road, Sydney, New South Wales 2006, Australia.

Conducting polymers are good candidates for electronic biomedical devices such as biosensors, artificial nerves, and electrodes for brain tissue. Functionalizing the conducting polymer surface with bioactive molecules can limit adverse immune reactions to the foreign body and direct tissue integration. In this work, we demonstrate a simple one-step method to attach biomolecules covalently to a conductive polymer. Electrochemically synthesized polypyrrole was activated using plasma immersion ion implantation (PIII) in nitrogen. A short treatment with relatively low ion fluence (20 s) was found to enable direct covalent immobilization of protein upon incubation in a protein solution, while the protein is easily removed from untreated polypyrrole by washing in buffer. The covalent nature of the protein immobilization was demonstrated by its resistance to elution when repeatedly washed with SDS detergent. Changes in the surface properties and their evolution with time after PIII activation were studied by a combination of attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), cyclic voltammetry, and water contact angle measurements. Notable changes in the chemistry of the modified layer in polypyrrole include the appearance of nitrile groups that gradually disappear with time and oxidation of the surface that increases over time in air. The kinetics of surface energy are consistent with the generation of radicals in the modified layer that are lost predominantly through oxidation. The conductivity of the modified surface layer (64 nm in thickness) decreases for low fluence treatments and is partially restored after high fluence treatment. This simple surface modification process opens up the possibility of creating biologically active interfaces for electro-stimulating biomedical devices and electrical sensing of neurological processes.
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http://dx.doi.org/10.1021/acsbiomaterials.7b00369DOI Listing
October 2017

Development of drug-loaded polymer microcapsules for treatment of epilepsy.

Biomater Sci 2017 Sep;5(10):2159-2168

ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, AIIM Facility, Innovation Campus, University of Wollongong, Northfields Avenue, Wollongong, NSW 2522, Australia.

Despite significant progress in developing new drugs for seizure control, epilepsy still affects 1% of the global population and is drug-resistant in more than 30% of cases. To improve the therapeutic efficacy of epilepsy medication, a promising approach is to deliver anti-epilepsy drugs directly to affected brain areas using local drug delivery systems. The drug delivery systems must meet a number of criteria, including high drug loading efficiency, biodegradability, neuro-cytocompatibility and predictable drug release profiles. Here we report the development of fibre- and sphere-based microcapsules that exhibit controllable uniform morphologies and drug release profiles as predicted by mathematical modelling. Importantly, both forms of fabricated microcapsules are compatible with human brain derived neural stem cells and differentiated neurons and neuroglia, indicating clinical compliance for neural implantation and therapeutic drug delivery.
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http://dx.doi.org/10.1039/c7bm00623cDOI Listing
September 2017

Preparation and in vitro assessment of wet-spun gemcitabine-loaded polymeric fibers: Towards localized drug delivery for the treatment of pancreatic cancer.

Pancreatology 2017 Sep - Oct;17(5):795-804. Epub 2017 Jun 3.

School of Biological Sciences, Illawarra Health and Medical Research Institute, Centre for Medical and Molecular Bioscience, University of Wollongong, NSW, Australia. Electronic address:

Background/objectives: There has been minimal improvement in the prognosis of pancreatic cancer cases in the past 3 decades highlighting the crucial need for more effective therapeutic approaches. A drug delivery system capable of locally delivering high concentrations of chemotherapeutics directly at the site of the tumor is clearly required. The aim of this study was to fabricate and characterize the biophysical properties of gemcitabine-eluting wet-spun polymeric fibers for localized drug delivery applications.

Methods/results: Fibers spun from alginate or chitosan solutions with or without the anticancer drug gemcitabine had a uniform surface area, were internally homogeneous and ranged from 50-120 μm in diameter. Drug encapsulation ranged from 13-52%, depending on the type and concentration of polymer used. Gemcitabine displayed first-order release kinetics where 64-82% of the loaded drug was rapidly released within the first 10 h followed by a sustained release over the next 134 h. A time dependent inhibition of ex vivo tumor spheroid growth and cell viability was observed after incubation with gemcitabine-loaded fibers but not control fibers.

Conclusion: With further development these studies could lead to the manufacture of a safe and effective delivery system designed to combat non-resectable pancreatic cancer for which currently there is minimal chance of cure.
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http://dx.doi.org/10.1016/j.pan.2017.06.001DOI Listing
June 2018

Evaluation of the Biocompatibility of Polypyrrole Implanted Subdurally in GAERS.

Macromol Biosci 2017 05 5;17(5). Epub 2016 Dec 5.

Department of Medicine, The University of Melbourne at St Vincent's Hospital, P.O. Box 2900, Fitzroy, Victoria, 3065, Australia.

This blinded controlled prospective randomized study investigates the biocompatibility of polypyrrole (PPy) polymer that will be used for intracranial triggered release of anti-epileptic drugs (AEDs). Three by three millimeters PPy are implanted subdurally in six adult female genetic absence epilepsy rats from Strasbourg. Each rat has a polymer implanted on one side of the cortex and a sham craniotomy performed on the other side. After a period of seven weeks, rats are euthanized and parallel series of coronal sections are cut throughout the implant site. Four series of 15 sections are histological (hematoxylin and eosin) and immunohistochemically (neuron-specific nuclear protein, glial fibrillary acidic protein, and anti-CD68 antibody) stained and evaluated by three investigators. The results show that implanted PPy mats do not induce obvious inflammation, trauma, gliosis, and neuronal toxicity. Therefore the authors conclude the PPy used offer good histocompatibility with central nervous system cells and that PPy sheets can be used as intracranial, AED delivery implant.
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http://dx.doi.org/10.1002/mabi.201600334DOI Listing
May 2017

A novel and facile approach to fabricate a conductive and biomimetic fibrous platform with sub-micron and micron features.

J Mater Chem B 2016 Feb 26;4(6):1056-1063. Epub 2015 Nov 26.

ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, University of Wollongong, Wollongong, NSW 2522, Australia.

The demands of multifunctional scaffolds have exceeded the passive biocompatible properties previously considered sufficient for tissue engineering. Herein, a novel and facile method used to fabricate a core-shell structure consisting of a conducting fiber core and an electrospun fiber shell is presented. This multifunctional structure simultaneously provides the high conductivity of conducting polymers as well as the enhanced interactions between cells and the sub-micron topographical environments provided by highly aligned cytocompatible electrospun fibers. Unlimited lengths of PEDOT:PSS-Chitosan-PLGA fibers loaded with an antibiotic drug, ciprofloxacin hydrochloride, were produced using this method. The fibers provide modulated drug release with excellent mechanical properties, electrochemical performance and cytocompatibility, which hold great promise for the application of conductive electrospun scaffolds in regenerative medicine.
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http://dx.doi.org/10.1039/c5tb02237aDOI Listing
February 2016

A simple and versatile method for microencapsulation of anti-epileptic drugs for focal therapy of epilepsy.

J Mater Chem B 2015 Sep 20;3(36):7255-7261. Epub 2015 Aug 20.

ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, AIIM Facility, University of Wollongong, Innovation Campus, Northfields Avenue, Wollongong, NSW 2522, Australia.

Nearly 30% of epilepsy cases cannot be adequately controlled with current medical treatments. The reasons for this are still not well understood, but there is a significant body of evidence pointing to the blood-brain barrier. Resective surgery can provide an alternative method of epilepsy control; however this treatment option is not suitable for most epilepsy sufferers. Local drug delivery through micro-injection to or implantation into the brain provides an innovative approach to bypass the blood-brain barrier for epilepsy treatment. In order to develop effective local delivery systems for anti-epilepsy drug (AED), we have prepared a variety of core-shell microcapsules via electrojetting, where a more hydrophobic polymer shell acts as a physical barrier to control the rate of drug release from the drug-loaded polymeric core. The resulting microcapsules demonstrate highly drug encapsulation efficiency, narrow size distribution and uniform morphology. Moreover, the release rate of AED can be modulated by controlling the morphologies of the core-shell microcapsules.
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http://dx.doi.org/10.1039/c5tb00675aDOI Listing
September 2015

Electro-stimulated release from a reduced graphene oxide composite hydrogel.

J Mater Chem B 2015 Mar 23;3(12):2530-2537. Epub 2015 Feb 23.

National Centre for Sensor Research, Dublin City University, Dublin 9, Ireland.

Electro-stimulated release was established using a novel, electro-conductive hydrogel system comprising Jeffamine polyetheramine and polyethylene glycol diglycidyl ether (PEGDGE) that was composited with reduced graphene oxide (rGO). The swelling response, morphology, mechanical and electrochemical properties of the composite hydrogel were investigated. Enhanced mechanical and electrical properties were observed with increased rGO content. Passive and electro-stimulated release of methyl orange (MO) from these gels was examined. A significant reduction in passive release of the dye was observed by incorporating rGO. Upon electrical stimulation, the release rate and dosage could be tuned through variation of the % w/w rGO, as well as the polarity and amplitude of the applied electric potential. A high level of control and flexibility was achieved demonstrating the applicability of this system for localised drug delivery applications.
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http://dx.doi.org/10.1039/c5tb00050eDOI Listing
March 2015
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