Leslie John Ray Foster

Chitosan adhesive for laser tissue repair: In vitro characterization

Publisher: Wiley

Date: 2005

DOI: 10.1002/LSM.20145

Abstract: Laser tissue repair usually relies on hemoderivate protein solders, based on serum albumin. These solders have intrinsic limitations that impair their widespread use, such as limited tensile strength of repaired tissue, poor solder solubility, and brittleness prior to laser denaturation. Furthermore, the required activation temperature of albumin solders (between 65 and 70 degrees C) can induce significant thermal damage to tissue. In this study, we report on the design of a new polysaccharide adhesive for tissue repair that overcomes some of the shortcomings of traditional solders. Flexible and insoluble strips of chitosan adhesive (elastic modulus approximately 6.8 Mpa, surface area approximately 34 mm2, thickness approximately 20 microm) were bonded onto rectangular sections of sheep intestine using a diode laser (continuous mode, 120 +/- 10 mW, lambda = 808 nm) through a multimode optical fiber with an irradiance of approximately 15 W/cm2. The adhesive was based on chitosan and also included indocyanin green dye (IG). The temperature between tissue and adhesive was measured using a small thermocouple (diameter approximately 0.25 mm) during laser irradiation. The repaired tissue was tested for tensile strength by a calibrated tensiometer. Murine fibroblasts were cultured in extracted media from chitosan adhesive to assess cytotoxicity via cell growth inhibition in a 48 hours period. Chitosan adhesive successfully repaired intestine tissue, achieving a tensile strength of 14.7 +/- 4.7 kPa (mean +/- SD, n = 30) at a temperature of 60-65 degrees C. Media extracted from chitosan adhesive showed negligible toxicity to fibroblast cells under the culture conditions examined here. A novel chitosan-based adhesive has been developed, which is insoluble, flexible, and adheres firmly to tissue upon infrared laser activation.

Application of polyethylene glycol to promote cellular biocompatibility of polyhydroxybutyrate films

Publisher: Hindawi Limited

Date: 2011

DOI: 10.1155/2011/473045

Abstract: Polyhydroxybutyrate (PHB) is a biomaterial with potential for applications in biomedical and tissue engineering however, its brittle nature and high crystallinity limit its potential. Blending PHB with a variety of PEGs produced natural-synthetic composite films composed of FDA-approved polymers with significant reductions in crystallinity, from 70.1% for PHB films to 41.5% for its composite with a 30% (w/w) loading of PEG2000. Blending also enabled manipulation of the material properties, increasing film flexibility with an extension to break of 2.49 ± 1.01% for PHB films and 8.32 ± 1.06% for films containing 30% (w/w) PEG106. Significant changes in the film surface properties, as measured by porosity, contact angles, and water uptake, were also determined as a consequence of the blending process, and these supported greater adhesion and proliferation of neural-associated olfactory ensheathing cells (OECs). A growth rate of 7.2 × 10 5 cells per day for PHB films with 30% (w/w) PEG2000 loading compared to 2.5 × 10 5 for PHB films was observed. Furthermore, while cytotoxicity of the films as measured by lactate dehydrogenase release was unaffected, biocompatibility, as measured by mitochondrial activity, was found to increase. It is anticipated that fine control of PEG composition in PHB-based composite biomaterials can be utilised to support their applications in medicinal and tissue engineering applications.

Manipulation of polyhydroxybutyrate properties through blending with ethyl-cellulose for a composite biomaterial

Publisher: Hindawi Limited

Date: 2011

DOI: 10.1155/2011/651549

Abstract: Polyhydroxybutyrate (PHB) is widely used as a biomaterial in medical and tissue-engineering applications, a relatively high crystallinity limits its application. Blending PHB with ethyl-cellulose (EtC) was readily achieved to reduce PHB crystallinity and promote its degradation under physiological conditions without undue influence on biocompatibility. Material strength of composite films remained unchanged at 6.5 ± 0.6 MPa with 40% (w/w) EtC loadings. Phase separation between the two biopolymers was determined with PHB crystallinity decreasing from 63% to 47% for films with the same loading. This reduction in crystallinity supported an increase in the degradation rates of composite films from 0.39 to 0.81% wk −1 for PHB and its composite, respectively. No significant change in morphology and proliferation of olfactory ensheathing cells were observed with the composites despite significant increases in average surface roughness ( R a ) of the films from 2.90 to 3.65 μ m for PHB and blends with 80% (w/w) EtC, respectively.

Towards scarless wound healing: A comparison of protein expression between human, adult and foetal fibroblasts

Publisher: Hindawi Limited

Date: 2014

DOI: 10.1155/2014/676493

Abstract: Proteins from human adult and foetal fibroblast cell lines were compared, focusing on those involved in wound healing. Proteins were separated through two-dimensional gel electrophoresis (2DE). Differences in protein spot intensity between the lineages were quantified through 3D gel scanning densitometry. Selected protein spots were excised, subjected to tryptic digests, prior to separation using HPLC with a linear ion trap mass spectrometer, and identified. Protein maps representing the proteomes from adult and foetal fibroblasts showed similar distributions but revealed differences in expression levels. Heat shock cognate 71 kDA protein, Tubulin alpha-1A chain, actin cytoplasmic-1, and neuron cytoplasmic protein were all expressed in significantly higher concentrations by foetal fibroblasts, nearly double those observed for their adult counterparts. Fructose bisphosphate aldolase A, Cofilin-1, Peroxiredoxin-1, Lactotransferrin Galectin-1, Profilin-1, and Calreticulin were expressed at comparatively higher concentrations by the adult fibroblasts. Significant differences in the expression levels of some proteins in human adult and foetal fibroblasts correlated with known differences in wound healing behaviour. This data may assist in the development of technologies to promote scarless wound healing and better functional tissue repair and regeneration.

Carbon nanotube mediated miscibility of polyhydroxyalkanoate blends and chemical imaging using deuterium-labelled poly(3-hydroxyoctanoate)

Publisher: Elsevier BV

Date: 08-2018

DOI: 10.1016/J.EURPOLYMJ.2018.05.031

Using Humidity to Control the Morphology and Properties of Electrospun BioPEGylated Polyhydroxybutyrate Scaffolds

Publisher: American Chemical Society (ACS)

Date: 05-10-2020

DOI: 10.1021/ACSOMEGA.0C02993

Biosynthesis and Characterization of Deuterated Polyhydroxyoctanoate

Publisher: American Chemical Society (ACS)

Date: 28-02-2006

DOI: 10.1021/BM050969L

Abstract: The synthesis of a polyhydroxyalkanoate with medium chain length alkyl substituents by Pseudomonas oleovoranswas investigated using protonated and deuterated forms of octanoic acid in a minimal salts medium. Cultivation with deuterated octanoic acid resulted in a reduced rate of polymer accumulation compared to that with its protonated counterpart (107 and 207 mg of polymer L(-1) of medium h(-1) of cultivation, respectively). Nuclear magnetic resonance and gas chromatography coupled mass spectrometry of the derivatized polymer was used to establish the extent and distribution of deuterium in the biopolymer. A partially deuterated heteropolymer with 3-hydroxyoctanoic acid as the main constituent was produced. Deuteration is an important tool for contrast variation studies using neutron scattering, but predicates that the deuterated polymer is otherwise comparable in its physiochemical and material properties to its protonated counterpart. In studies reported here, the deuterated biopolymer exhibited an additional diffraction maximum at 7.55 A and slight differences in its melting point (60 and 55 degrees C) and glass transition temperature (-39 and -36 degrees C) when compared to its protonated equivalent. While significant differences between the protonated and deuterated biopolymers were determined, our results support the use of this deuterated polyhydroxyalkanoate in its application in investigations using analytical neutron scattering techniques.

Poly(ethylene glycol)-modulated cellular biocompatibility of polyhydroxyalkanoate films

Publisher: Wiley

Date: 14-02-2013

DOI: 10.1002/PI.4451

Application of low loading of collagen in electrospun poly[(L-lactide)-co-(ε-caprolactone)] nanofibrous scaffolds to promote cellular biocompatibility

Publisher: Wiley

Date: 05-11-2014

DOI: 10.1002/PI.4631

Investigation of the phase morphology of bacterial PHA inclusion bodies by contrast variation SANS

Publisher: Elsevier BV

Date: 11-2006

DOI: 10.1016/J.PHYSB.2006.05.126

Deuterated polymers for probing phase separation using infrared microspectroscopy

Publisher: American Chemical Society (ACS)

Date: 08-01-2014

DOI: 10.1021/BM4017012

Abstract: Infrared (IR) microspectroscopy has the capacity to determine the extent of phase separation in polymer blends. However, a major limitation in the use of this technique has been its reliance on overlapping peaks in the IR spectra to differentiate between polymers of similar chemical compositions in blends. The objective of this study was to evaluate the suitability of deuteration of one mixture component to separate infrared (IR) absorption bands and provide image contrast in phase separated materials. Deuteration of poly(3-hydroxyoctanoate) (PHO) was achieved via microbial biosynthesis using deuterated substrates, and the characteristic C-D stretching vibrations provided distinct signals completely separated from the C-H signals of protonated poly(3-hydroxybutyrate) (PHB). Phase separation was observed in 50:50 (% w/w) blends as domains up to 100 μm through the film cross sections, consistent with earlier reports of phase separation observed by scanning electron microscopy (SEM) of freeze-fractured protonated polymer blends. The presence of deuterated phases throughout the film suggests there is some miscibility at smaller length scales, which increased with increasing PHB content. These investigations indicate that biodeuteration combined with IR microspectroscopy represents a useful tool for mapping the phase behavior of polymer blends.

A Tuneable Switch for Controlling Environmental Degradation of Bioplastics: Addition of Isothiazolinone to Polyhydroxyalkanoates

Publisher: Public Library of Science (PLoS)

Date: 11-10-2013

DOI: 10.1371/JOURNAL.PONE.0075817

Chitosan as a biomaterial: Influence of degree of deacetylation on its physiochemical, material and biological properties

Publisher: Public Library of Science (PLoS)

Date: 25-08-2015

DOI: 10.1371/JOURNAL.PONE.0135153

Application of a novel film sealant technology for penetrating corneal wounds: An ex-vivo study

Publisher: MDPI AG

Date: 03-05-2020

DOI: 10.3390/APP10093193

Abstract: Aim: To compare the burst pressures of corneal wounds closed with a laser-activated, chitosan-based thin film adhesive against self-seal, sutures and cyanoacrylate. Methods: 2, 4 or 6 mm penetrating corneal wounds were created on 100 freshly enucleated bovine eyes. The wounds were closed using a laser-activated chitosan adhesive (n = 30), self-sealed (control) (n = 30), sutures (n = 20) or cyanoacrylate glue (Histoacryl®) (n = 20). The corneoscleral rim was dissected and mounted onto a custom burst pressure testing chamber. Water was pumped into the chamber at 9ml/hr. The fluid pressure prior to wound leakage was recorded as the ‘burst pressure’. Results: The burst pressure for the 2, 4 and 6 mm wounds were 239.2 mmHg (SD = ±102.4), 181.7 mmHg (SD = ±72.8) and 77.4 mmHg (SD = ±37.4) (p 0.00001), respectively, for chitosan adhesive. Burst pressure was 36.4 mmHg (SD = ±14.7), 4.8 mmHg (SD = ±4.9) and 2.7 mmHg (SD = ±1.3) (p 0.00001), respectively, for the self-sealed group. For 4 and 6mm wounds, burst pressures with sutures were 33.0 mmHg (SD = ±19) and 23.5 mmHg (SD = ±17.4) (p = 0.0087), respectively. For cyanoacrylate, burst pressures for 2 and 4 mm wounds were 698 mmHg (SD = ±240.3) and 494.3 mmHg (SD = ±324.6) (p = 0.020087), respectively. Conclusion: This laser-activated chitosan-based adhesive sealed bovine corneal wounds up to 6 mm in length. Burst pressure was higher for the adhesive than sutured or self-sealed wounds, but lower than for cyanoacrylate.

SurgiLux: A novel thin film, laser-activated bioadhesive for corneal repair

Publisher: Trans Tech Publications, Ltd.

Date: 04-2012

DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.506.7

Abstract: Laser activated SurgiLux ® technology was examined to determine its suitability as an ocular wound sealant. SurgiLux showed suitable strength and flexibility as well as moisture content for applications in the eye. In comparison to conventional microsuturing complemented with fibrin sealant, application of the SurgiLux technology was up to 5 times faster and the strength of the repaired wounds up to 7 times greater, with a 6 mm incision withstanding 235 mm Hg pressure compared to 120 mm Hg for sutures with fibrin.

Diversity of microbial species implicated in keratitis: A review

Publisher: Bentham Science Publishers Ltd.

Date: 30-11-2012

DOI: 10.2174/1874364101206010110

Centrifugally spun polyhydroxybutyrate fibres: Accelerated hydrolytic degradation studies

Publisher: Elsevier BV

Date: 2005

DOI: 10.1016/J.POLYMDEGRADSTAB.2003.11.012

Sutureless nerve repair with ECM bioscaffolds and laser‐activated chitosan adhesive

Publisher: Wiley

Date: 29-08-2017

DOI: 10.1002/JBM.B.33975

Abstract: The outcome of peripheral nerve repair following transection is influenced by a number of factors but almost all approaches require anastomosis of the nerve using technically demanding microsurgical procedures. However, the use of sutures presents a number of unavoidable challenges including additional nerve trauma, stimulation of an inflammatory response, and endoneural fibrosis. The objective of the present study was to determine the efficacy of a sutureless approach to nerve repair. A rat sciatic nerve transection model was used with a laser-activated, chitosan-based adhesive (SurgiLux), combined with different forms of extracellular matrix (ECM), known to promote Schwann cell proliferation and nerve growth both in peripheral nerve applications. Following a 5 mm transection of the sciatic nerve, nerve guide wraps were prepared using: (1) laser-activated adhesive (SurgiLux) alone, (2) SurgiLux incorporating ECM (SurgiLux ECM), (3) ECM secured using SurgiLux, and (4) ECM secured using 8-0 Prolene sutures. A no treatment groups was used as a negative control. Evaluation of tissue remodeling was conducted with histolomorphometric assessment of neuroma, integrity of repair, nerve immunolabeling, ratio of myelinated to non-myelinated fibers, and amount of connective tissue. Quantitative and semi-quantitative analysis of the repaired nerve transections at 6 and 12 weeks showed that that SurgiLux incorporating powdered ECM (SurgiLux ECM), SurgiLux alone and ECM alone all improved the healing response compared to no-treatment controls, with less fibrotic tissue and more nerve staining. Histologic scoring showed that the SurgiLux ECM group showed the greatest increase in histologic score between the two time points tested. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1698-1711, 2018.

Polyhydroxybutyrate and its copolymer with polyhydroxyvalerate as biomaterials: Influence on progression of stem cell cycle

Publisher: American Chemical Society (ACS)

Date: 17-09-2010

DOI: 10.1021/BM1007579

Abstract: Poly(3-hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) are biopolyesters reported to provide favorable microenvironments for cell culture and possess potential for tissue engineering applications. Both biopolymers have been investigated for applications in a variety of medical scenarios, including nerve and bone repair. This study investigated the influence these biomaterials exerted on cell cycle progression of olfactory ensheathing cells (OECs) and mesenchymal stem cells (MSCs) commonly used in the engineering of nerve and bone tissues. Cell cycle regulation is important for cell survival analysis revealed that the biomaterials induced significant cell cycle progression in both MSCs and OECs. Significantly higher percentages of cells were cycled at synthesis (S) phase of the cycle on PHBV films compared to PHB, with MSCs more susceptible than OECs. Furthermore, detection of early stages of apoptotic activation showed significant differences in the two cell populations exhibiting necrosis and apoptosis when cultivated on the biomaterials. OECs compromised on PHB (5.6%) and PHBV (2.5%) compared to MSCs with 12.6% on PHB and 17% on PHBV. Significant differences in crystallinity and surface rugosity were determined between films of the two biomaterials, 88% and 1.12 μm for PHB and 76% and 0.72 μm for PHBV. While changes in surface properties may have influenced cell adhesion, the work presented here suggests that application of these biomaterials in tissue engineering are specific to cell type and requires a detailed investigation at the cell-material interface.

Drug-delivery study and estimation of polymer-solvent interaction parameter for bisacrylate ester-modified Pluronic hydrogels

Publisher: Elsevier BV

Date: 08-2008

DOI: 10.1016/J.IJPHARM.2008.04.032

Abstract: In this study, Pluronic F127 hydrogels were characterised as an injectable system for the controlled release of drugs with variable molecular weights (FITC-Dextran at 70 and 40 kDa). In addition, the polymer-solvent interaction parameter (chi) was successfully estimated. Pluronic hydrogels (10-25 wt.%) were redox cured and their swelling behaviour investigated in PBS (pH 7.45) at 37 degrees C. After swelling to equilibrium, the hydrogels were compressed and the rubber-elasticity theory was applied to evaluate chi. Tensile tests proved the hydrogels were elastic and their chi values ranged between 0.50 and 0.53. The full drug load could be delivered over a period of approximately 15 h suggesting that redox cured Pluronic F127 hydrogels can function as injectable systems for controlled and sustained release of macromolecules.

Coalescence of extracellular matrix (ECM) from porcine urinary bladder (UBM) with a laser-activated chitosan-based surgical adhesive

Publisher: Informa UK Limited

Date: 08-05-2012

DOI: 10.1163/092050611X585431

Corneal Sealants in Clinical Use: A Systematic Review

Publisher: Informa UK Limited

Date: 27-05-2020

DOI: 10.1080/02713683.2020.1764052

BioPEGylation of polyhydroxybutyrate promotes nerve cell health and migration

Publisher: American Chemical Society (ACS)

Date: 10-12-2014

DOI: 10.1021/BM401572A

Abstract: This study reports on the superior suitability of Polyhydroxybutyrate-polyethylene glycol hybrid polymers biosynthesised by Cupriavidus necator over PHB as biomaterials for tissue engineering. Incorporation of PEG106 (DEG) during PHB biosynthesis reduced crystallinity, molecular weight, and hydrophobicity while improving mechanical properties. In vitro olfactory ensheathing cell (OEC) proliferation was enhanced by cultivation on PHB-b-DEG films. Cultivation on PHB and PHB-b-DEG films showed no cytotoxic responses and cell viability and membrane integrity was sustained. PHB-b-DEG films promoted OECs entering into the DNA replication (S) phase and mitotic (G2-M) phase during the cell growth cycle and apoptosis was low. This study also confirmed an association between the level of neurite-outgrowth inhibitory protein (Nogo) and receptor pair Ig-like receptor B (PirB) expression and cell proliferation, both being down-regulated in cells grown on hybrid films when compared with PHB and asynchronous growth. Thus, DEG-terminated PHB-based biomaterials have great potential as biological scaffolds supporting nerve repair.

Biosynthesis, properties and potential of natural-synthetic hybrids of polyhydroxyalkanoates and polyethylene glycols

Publisher: Springer Science and Business Media LLC

Date: 25-04-2007

DOI: 10.1007/S00253-007-0976-Y

Abstract: Chemical conjugation with poly(ethylene glycols) (PEGs) are established procedures to facilitate solubilisation of hydrophobic compounds. Such techniques for PEGylation have been applied to polyhydroxybutyrate. 'BioPEGylation' of such polyhydroxyalkanoates (PHAs) to form natural-synthetic hybrids has been demonstrated through the addition of PEGs to microbial cultivation systems. The strategic addition of certain PEGs not only supports hybrid synthesis but may also provide a technique for control of PHA composition and molecular mass, and by extension, their physico-mechanical properties. PHA composition and molecular mass control by PEGs is dependent upon the polyethers' molecular mass, loading in the cultivation system, time of introduction and microbial species. Hybrid characterisation studies are in their infancy, but results to date suggest that PHA-PEG hybrids have subtle, but significant, differences in their physiochemical and material properties as a consequence of the PEGylation.

A comprehensive protein expression profile of extracellular matrix biomaterial derived from porcine urinary bladder

Publisher: Future Medicine Ltd

Date: 03-2012

DOI: 10.2217/RME.12.6

Abstract: Aims: To generate a comprehensive profile of the protein composition of xenogeneic biomaterial, derived from porcine urinary bladder matrix (UBM). Materials & methods: Tunica layers and muscularis mucosa were removed from bladders using mechanical delamination. UBM was prepared using a solution of peracetic acid in ethanol, lyophilized then milled into powder. UBM biomaterial was subjected to tryptic digests and components separated using high-performance liquid chromatography with an ion trap mass spectrometer and identified through databases. Results: A repertoire of 129 proteins with neurotrophic, antiangiogenic and tumor-suppressive activities and those associated with tissue remodeling and wound repair were identified. Conclusion: This study provides the first insight into the complex nature of the UBM and how its application may be tailored for specific applications in regenerative medicine. We propose that the UBM be further investigated for reconstructive and regenerative remodeling of cardiac and dermal tissues, as well as peripheral nerves.

In vivo deuteration strategies for neutron scattering analysis of bacterial polyhydroxyoctanoate

Publisher: Springer Science and Business Media LLC

Date: 15-05-2008

DOI: 10.1007/S00249-008-0333-9

Abstract: The cultivation of microorganisms on deuterated substrates has allowed us to control deuterium incorporation into biopolymer systems which is important for characterisation using neutron scattering techniques. Bacterial polyhydroxyoctanoate (PHO) is a polyester formed within inclusions inside bacterial cells and was deuterated in vivo under various conditions to characterise the formation of these inclusions by neutron scattering. Manipulation of deuterated media during microbial growth and PHO production phases resulted in polymer with partial or complete substitution of hydrogen by deuterium, as shown by gas chromatography. Sequential feeding of hydrogenated and deuterated forms of the same precursor was used to demonstrate that neutron scattering analysis could be used to differentiate between chemically similar phases in these polymer inclusions.

A chitosan based, laser activated thin film surgical adhesive, 'Surgilux': Preparation and demonstration

Publisher: MyJove Corporation

Date: 23-10-2012

DOI: 10.3791/3527

Adhesive biomaterials for tissue reconstruction

Publisher: Wiley

Date: 21-09-2008

DOI: 10.1002/JCTB.1771

Effect of surface modification of poly(L-lactide-co-ε-caprolactone) membranes by low-pressure plasma on support cell biocompatibility

Publisher: Elsevier BV

Date: 11-2016

DOI: 10.1016/J.SURFCOAT.2016.07.058

BioPEGylation of Polyhydroxyalkanoates: Influence on Properties and Satellite-Stem Cell Cycle

Publisher: American Chemical Society (ACS)

Date: 29-08-2008

DOI: 10.1021/BM800418E

Abstract: The addition of poly(ethylene glycol), PEG, to bioprocessing systems producing polyhydroxyalkanoates (PHAs), has been reported as a means of their molecular weight control and can also support bioPEGylation, resulting in hybrids with hiphillic properties. However, the study of such natural-synthetic hybrids of PHA-b-PEG is still in its infancy. In this study, we report the influence of bioPEGylation of polyhydroxyoctanoate (PHO) on its physiochemical, material, and biological properties. Consistent with previous studies, bioPEGylation with diethylene glycol (DEG) showed a significant reduction in PHA molecular weight (57%). In comparison to solvent cast films of PHO, PHO-b-DEG films possessed a noticeable X-ray diffraction peak at 9.82 degrees and increased Young's modulus of 11 Gpa (83%). Potential biocompatibility was investigated by measuring the early phase of apoptosis in myoblastic satellite-stem cells (C2C12). Comparative analysis of cell proliferation and progression in the presence of the mcl-PHA and its hybrid showed that the latter induced significant cell cycle progression: the first time a biomaterial has been shown to do so. Microtopographies of the film surfaces demonstrated that these differences were not due to changes in surface morphology both polymers possessed average surface rugosities of 1.4 +/- 0.2 microm. However, a slight decrease in surface hydrophobicity (3.5 +/- 0.9 degrees) due to the hydrophilic DEG may have exerted an influence. The results support the further study of bioPEGylated PHAs as potential biomaterials in the field of tissue engineering.

Chitosan adhesive for laser tissue repair

Publisher: SPIE

Date: 09-02-2006

DOI: 10.1117/12.645155

Chitosan-vancomysin composite biomaterial as a laser activated surgical adhesive with regional antimicrobial activity

Publisher: American Chemical Society (ACS)

Date: 16-11-2010

DOI: 10.1021/BM101028G

Abstract: We have used laser irradiation to enhance the natural adhesiveness of chitosan to form a thin film surgical adhesive. Prevention of infection at surgical sites often utilizes systemic provision of antibiotics with reduced local efficacy and potential side effects. In the work reported here, we investigate the bactericidal properties of laser-irradiated chitosan films and their impregnation with the antibiotic vancomycin. Despite strong efficacy in solution, chitosan films showed no antimicrobial activity against representatives of common pathogens Escherichia coli , Staphylococcus aureus , and S. epidermidis . In contrast, a composite of chitosan adhesive and the antibiotic vancomycin showed therapeutically significant release profiles greater that the Minimum Bactericidal Concentrations (MBCs) for the Staphylococci over a 28 day period. These composite films had greater crystallinity, up to 28 ± 3 compared to 8.9 ± 2%, for its unblended counterpart. Despite a significant increase in material strength from 31.4 ± 4 to 77.5 ± 5 MPa, flexibility was still maintained with an elongation to break around 5 ± 2% and fold endurance of approximately 30 ± 3-folds. Laser irradiation had no apparent effect on the release or activity of the antibiotic which survived transient temperatures at the film-tissue interface during infrared irradiation of around 54 °C. Furthermore, significant adhesive strength was still apparent, 15.6 ± 2 KPa. Thus, we have developed a laser-activated bioadhesive with the potential to close wounds while facilitating the prevention of microbial infection through local release of antibiotic targeted to the site of potential infection.

In vitro hydrolytic degradation of centrifugally spun polyhydroxybutyrate-pectin composite fibres

Publisher: Wiley

Date: 29-09-2009

DOI: 10.1002/PI.2682

Production and use of deuterated polyhydroxyoctanoate in structural studies of PHO inclusions

Publisher: Elsevier BV

Date: 11-2007

DOI: 10.1016/J.JBIOTEC.2007.03.018

Abstract: This work reports on the biosynthesis of polyhydroxyalkanoates with medium chain length alkyl substituents in the side chain by Pseudomonas oleovorans using hydrogenated and deuterated substrates. These investigations aimed to obtain polyhydroxyalkanoates with varying degrees of deuterium substitution, and establish whether they are suitable analogues for structural investigation. In order to understand the formation and structure of inclusions in their native state, whole inclusions were isolated from microbial cells and were analysed using Small Angle Neutron Scattering. A contrast variation study was conducted on hydrogenated and deuterated inclusions of polyhydroxyoctanoate, as well as inclusions resulting from co-feeding or sequentially feeding different precursors. The data indicated a core/shell structure resulting from feeding hydrogenated followed by perdeuterated PHO precursor, and demonstrated the utility of this analysis for characterising chemically similar systems.

Chitosan films are NOT antimicrobial

Publisher: Springer Science and Business Media LLC

Date: 16-10-2011

DOI: 10.1007/S10529-010-0435-1

Abstract: Chitosan is a promising biomaterial for biomedical applications and is currently applied as wound dressings. While chitosan solutions demonstrate strong bactericidal activity against a range of medically important bacteria, the study here reports a loss of this beneficial property in thin films cast from the same solutions. Chitosan films (20 microm) showed no inhibitory effects against Escherichia coli, Staphylococcus aureus or S. epidermidis species. In contrast, solutions used to prepare the films showed almost complete inhibition (approximately 98 ± 2%) when tested on bacterial lawns and in liquid cultures. Increased acidity of the chitosan solutions (pH 5) was shown to promote the bactericidal effects of this biopolymer. The concept that devices fabricated from chitosan have an inherent antimicrobial activity is suggested as an important misconception.

Structural evolution and stability of sol-gel biocatalysts

Publisher: Elsevier BV

Date: 11-2006

DOI: 10.1016/J.PHYSB.2006.05.257

Polyhydroxyalkanoate-based natural–synthetic hybrid copolymer films: A small-angle neutron scattering study

Publisher: Elsevier BV

Date: 11-2006

DOI: 10.1016/J.PHYSB.2006.06.079

Small-angle neutron scattering characterization of polyhydroxyalkanoates and their BioPEGylated hybrids in solution

Publisher: American Chemical Society (ACS)

Date: 08-12-2008

DOI: 10.1021/BM7006289

Abstract: Small-angle neutron scattering was used to probe the molecular conformation of various polyhydroxyalkanoates (PHAs) and their bioPEGylated counterparts (PHA- b-PEG). Analysis of neutron scattering profiles of these polymers dissolved in deuterated chloroform at various concentrations from dilute (approximately 0.1% w/v) to semidilute (approximately 7% w/v) showed the two distinct regimes and established overlap concentrations around 4-9 mg mL(-1). Scattering profiles were similar for all polymers investigated power laws of approximately Q(-1.66) at high Q demonstrated that chloroform behaves as a good solvent for PHAs and suggests that under conditions synonymous with processing the solvated chains were swollen rather than in Gaussian conformation as previously reported. A gradual change to Guinier knees was followed by slopes of Q(-3) suggesting the presence of supramolecular structures at larger length scales. These observations in both the dilute and semidilute concentrations have not been previously reported. Zimm analysis of the data provided gyration radii and absolute molecular weights consistent with trends established using light scattering but showed some variation in their second virial coefficients. While natural-synthetic hybrids of PHA- b-PEG can self-assemble into microporous films, they showed no noticeable differences in chain conformation when in solution, the fabricating medium. This suggests that some form of entropic inducement is required.

Environmental degradation and biofouling of 'green' plastics including short and medium chain length polyhydroxyalkanoates

Publisher: Wiley

Date: 18-12-2010

DOI: 10.1002/PI.2746

Biopolymer Deuteration for Neutron Scattering and Other Isotope-Sensitive Techniques

Publisher: Elsevier

Date: 2015

DOI: 10.1016/BS.MIE.2015.06.015

Abstract: The use of microbial biosynthesis to produced deuterated recombinant proteins is a well-established practice in investigations of the relationship between molecular structure and function using neutron scattering and nuclear magnetic resonance spectroscopy. However, there have been few reports of using microbial synthetic capacity to produce labeled native biopolymers. Here, we describe methods for the production of deuterated polyhydroxyalkanoate biopolyesters in bacteria, the polysaccharide chitosan in the yeast Pichia pastoris, and cellulose in the bacterium Gluconacetobacter xylinus. The resulting molecules offer not only multiple options in creating structural contrast in polymer blends and composites in structural studies but also insight into the biosynthetic pathways themselves.

A natural-synthetic hybrid copolymer of polyhydroxyoctanoate-diethylene glycol: biosynthesis and properties

Publisher: Elsevier BV

Date: 08-2005

DOI: 10.1016/J.POLYMER.2005.05.012

Electrospun polyhydroxybutyrate and poly(L-lactide-co-ε-caprolactone) composites as nanofibrous scaffolds

Publisher: Hindawi Limited

Date: 2014

DOI: 10.1155/2014/741408

Abstract: Electrospinning can produce nanofibrous scaffolds that mimic the architecture of the extracellular matrix and support cell attachment for tissue engineering applications. In this study, fibrous membranes of polyhydroxybutyrate (PHB) with various loadings of poly(L-lactide-co- ε -caprolactone) (PLCL) were successfully prepared by electrospinning. In comparison to PLCL scaffolds, PLCL blends with PHB exhibited more irregular fibre diameter distributions and higher average fibre diameters but there were no significant differences in pore size. PLCL/PHB scaffolds were more hydrophilic ( °) with significantly reduced tensile strength (ca. 1 MPa) compared to PLCL scaffolds ( 150.9 ± 2.8 ∘ and 5.8 ± 0.5 MPa). Increasing PLCL loading in PHB/PLCL scaffolds significantly increased the extension at break, (4–6-fold). PLCL/PHB scaffolds supported greater adhesion and proliferation of olfactory ensheathing cells (OECs) than those exhibiting asynchronous growth on culture plates. Mitochondrial activity of cells cultivated on the electrospun blended membranes was enhanced compared to those grown on PLCL and PHB scaffolds (212, 179, and 153%, resp.). Analysis showed that PLCL/PHB nanofibrous membranes promoted cell cycle progression and reduced the onset of necrosis. Thus, electrospun PLCL/PHB composites promoted adhesion and proliferation of OECs when compared to their in idual PLCL and PHB components suggesting potential in the repair and engineering of nerve tissue.

Influence of biphasic stimulation on olfactory ensheathing cells for neuroprosthetic devices

Publisher: Frontiers Media SA

Date: 04-10-2016

DOI: 10.3389/FNINS.2016.00432

University Of Alabama At Huntsville

Location: United States of America

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University Of New South Wales - Randwick Campus

Location: Australia

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Aegros Ltd

Location: Australia

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Repartech Pty Ltd

Location: Australia

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Design And Characterisation Of A Polysaccharide-based Biomaterial For Tissue Adhesion

Start Date: 2003

End Date: 2004

Funder: Australian Research Council

Production Of Biodegradable Polyhydroxyalkanoate Polymers Using Advanced Biological Wastewater Treatment Process Technology

Start Date: 2004

End Date: 2006

Funder: Australian Research Council

Application Of Sutureless Technology 'SurgiLux' For Dura Mater Repair: A Proof Of Concept Study

Start Date: 2010

End Date: 2011

Funder: National Health and Medical Research Council

A 5-D Correlative Imaging Platform: Combining The Strengths Of Light And Electron Microscopy

Start Date: 2010

End Date: 2010

Funder: Australian Research Council

Novel Coatings For Steel

Start Date: 2002

End Date: 2004

Funder: Australian Research Council

An Ocular Thin Film Adhesive With Local Drug Delivery Capabilities.

Start Date: 2014

End Date: 2018

Funder: National Health and Medical Research Council

Application Of Novel Sutureless Technology For Eye Surgery

Start Date: 2010

End Date: 2014

Funder: National Health and Medical Research Council

Effective Nerve Repair: Australian-American Synergistic Technology

Start Date: 2010

End Date: 2010

Funder: Council for International Exchange of Scholars

Development Of A Light-Activated Bioadhesive For Low Temperature Tissue Repair

Start Date: 2007

End Date: 2009

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0345899

Start Date: 11-2003

End Date: 12-2005

Amount: $106,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0452860

Start Date: 2004

End Date: 12-2006

Amount: $445,000.00

Funder: Australian Research Council

Discovery Projects - Grant ID: DP0772153

Start Date: 2007

End Date: 12-2010

Amount: $310,000.00

Funder: Australian Research Council

Linkage Projects - Grant ID: LP0212098

Start Date: 04-2002

End Date: 12-2005

Amount: $275,000.00

Funder: Australian Research Council

Linkage Infrastructure, Equipment And Facilities - Grant ID: LE100100010

Start Date: 12-2010

End Date: 12-2010

Amount: $720,000.00

Funder: Australian Research Council