Preparation and characterization of a novel antimicrobial film dressing for wound healing application

Antibacterial activity and good mechanical properties are some of the characteristics required for an appropriate film dressing. A novel polymer blend was developed for wound healing application. Twenty-four formulations using the polymers chitosan, poly(vinyl alcohol) and/or ɛ-Polylysine and the plasticizer glycerol were designed using factorial design and then the films were prepared by the casting/solvent evaporation method. Seventeen films were obtained among the twenty-four proposed formulations that were characterized by Field Emission Scanning Electron Microscopy (FE-SEM) and Fourier Transform Infrared Spectroscopy (FTIR). Mechanical properties, such as tensile strength (σ), elongation at break (ɛ) and Young's modulus (Y) as well as antibacterial properties were determined. The best candidate was then further analyzed with regard to porosity, Water Vapor Transmission Rate (WVTR), swelling and cytotoxicity experiments. The results showed a film with semi-occlusive characteristics, good mechanical properties and no toxic. Incorporation of ɛ-Polylysine increased antibacterial activity against gram-negative (Escherichia coli) and gram-positive (Staphylococcus aureus) bacteria

Controlled delivery of ibuprofen from poly(vinyl alcohol)-poly (ethylene glycol) interpenetrating polymeric network hydrogels / 药物分析学报

Hydrogels composed of poly(vinyl alcohol) (PVA) and poly(ethylene glycol) (PEG) were synthesized using glutaraldehyde as crosslinker and investigated for controlled delivery of the common anti-inflammatory drug, ibuprofen (IBF). To regulate the drug delivery, solid inclusion complexes (ICs) of IBF in β–cyclodextrin (β–CD) were prepared and added to the hydrogels. The ICs were prepared by the microwave irradiation method, which is more environmentally benign. The formation of IC was confirmed by various analytical techniques and the synthesized hydrogels were also characterized. Controlled release of drug was achieved from the hydrogels containing the ICs in comparison to the rapid release from hydrogels containing free IBF. The preliminary kinetic analysis emphasized the crucial role of β–CD in the drug release process that in-fluences the polymer relaxation, thereby leading to prolonged release. The cytotoxicity assay validated the hydrogels as non-toxic in nature and hence can be utilized for controlled delivery of IBF.

Physicochemical Characterization and Bioactivity of an Improved Chitosan Scaffold Cross-Linked With Polyvinyl Alcohol for Corneal Tissue Engineering Applications

Background: Corneal blindness resulting from various medical condition affects millions worldwide. The rapid developing field of tissue engineering offers the potential to develop a tissue-engineered cornea that adheres very closely to the native cornea for transplantation. The design of a scaffold with mechanical properties and transparency similar to that of natural cornea is vital for the regeneration of corneal tissues. Hence, there is a need to investigate this relatively inexpensive but an improved scaffold to assist in human corneal stem cells delivery. Aim and Study Design: The present study aimed at to prepare and investigate the properties of poly vinyl alcohol (PVA)/chitosan blended scaffold by further cross-linking with 1-Ethyl-3-(3-dimethyl amino propyl)-carbodiimide (EDC), 2 N-Hydroxysuccinimide (NHS) as potential in vitro carrier for human limbal epithelial cells delivery. Results: After the viscosity measurement, the PVA/Chitosan scaffold was observed by Fourier transform infrared spectroscopy (FT-IR). The water absorbency of PVA/Chitosan was increased 361% by swelling. Compression testing demonstrated that by increasing the amount of chitosan, the strength of the scaffold could be increased to 16 × 10−1 Mega Pascal Pressure Unit (MPa). Our degradation results revealed by mass loss shows that scaffold degraded gradually implies slow degradation but shown enhanced the biomechanical properties. In vitro 3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide (MTT) assay showed good cell proliferation and growth in the scaffold. Besides the above, the present study aimed at exploring the effects if any observed with PVA/chitosan and other cross linkers on cell morphology and phenotype using H&E staining. Our MTT assay results and the cells observed on these membranes confirmed that the safer and improved method of preparation of membrane could increase the cells adhesion and growth on the substrata. Conclusion: Hence, we strongly believe the use of this improved PVA/chitosan polymer scaffold has potential to cut down the disadvantages of human amniotic membrane (HAM) for corneal epithelium in ocular surface surgery in future after successful experimentation with clinical trials.

Chitosan-Poly(Vinyl Alcohol) Nanofibers by Free Surface Electrospinning for Tissue Engineering Applications

Deformities in tissues and organs can be treated by using tissue engineering approach offering the development of biologically functionalized scaffolds from a variety of polymer blends which mimic the extracellular matrix and allow adjusting the material properties to meet the defect architecture. In recent years, research interest has been shown towards the development of chitosan (CS) based biomaterials for tissue engineering applications, because of its minimal foreign body reactions, intrinsic antibacterial property, biocompatibility, biodegradability and ability to be molded into various geometries and forms thereby making it suitable for cell ingrowth and conduction. The present work involves the fabrication of nanofibrous scaffold from CS and poly(vinyl alcohol) blends by free-surface electrospinning method. The morphology and functional characteristics of the developed scaffolds were assessed by field emission scanning electron microscopy and fourier transformed infra-red spectra analysis. The morphological analysis showed the average fiber diameter was 269 nm and thickness of the mat was 200–300 µm. X-ray diffraction study confirmed the crystalline nature of the prepared scaffolds, whereas hydrophilic characteristic of the prepared scaffolds was confirmed by measured contact angle. The scaffolds possess an adequate biodegradable, swelling and mechanical property that is found desirable for tissue engineering applications. The cell study using umbilical cord blood-derived mesenchymal stem cells has confirmed the in vitro biocompatibility and cell supportive property of the scaffold thereby depicting their potentiality for future clinical applications.

Membrane adsorber for endotoxin removal

ABSTRACT The surface of flat-sheet nylon membranes was modified using bisoxirane as the spacer and polyvinyl alcohol as the coating polymer. The amino acid histidine was explored as a ligand for endotoxins, aiming at its application for endotoxin removal from aqueous solutions. Characterization of the membrane adsorber, analysis of the depyrogenation procedures and the evaluation of endotoxin removal efficiency in static mode are discussed. Ligand density of the membranes was around 7 mg/g dry membrane, allowing removal of up to 65% of the endotoxins. The performance of the membrane adsorber prepared using nylon coated with polyvinyl alcohol and containing histidine as the ligand proved superior to other membrane adsorbers reported in the literature. The lack of endotoxin adsorption on nylon membranes without histidine confirmed that endotoxin removal was due to the presence of the ligand at the membrane surface. Modified membranes were highly stable, exhibiting a lifespan of approximately thirty months.

RESUMO A superfície de membranas planas de nylon foi modificada utilizando-se bisoxirano como espaçador e poli(álcool vinílico) para recobrimento das membranas. O aminoácido histidina foi utilizado como ligante para endotoxinas, visando à sua aplicação na remoção de endotoxinas a partir de soluções aquosas. São discutidas as etapas de caracterização do adsorvedor com membranas, análise do procedimento de despirogenização e avaliação da eficiência de remoção em modo estático. A densidade de ligantes nas membranas foi em torno de 7 mg/g membrana (massa seca), permitindo uma remoção de endotoxinas de até 65%. O desempenho das membranas preparadas com nylon e recobertas com poli(álcool vinílico) contendo histidina como ligante foi superior ao de outros adsorvedores com membranas descritos na literatura. A ausência de adsorção de endotoxinas em membranas sem histidina confirma que a remoção das endotoxinas deve-se exclusivamente à presença do ligante na superfície da membrana. As membranas modificadas mostraram-se bastante estáveis, exibindo um tempo de vida superior a 30 dias.

Interpenetrating polymer network of cross-linked blend microspheres for controlled release of Acebutolol HCl.

Carbohydrate polymeric blend microspheres consisting of chitosan (CS) and poly (vinyl alcohol) (PVA) were prepared by water-in-oil (W/O) emulsion method. These microspheres were crosslinked with glutaraldehyde and loaded with Acebutolol HCl, an anti hypertensive drug. The microspheres were characterized by Fourier transform infrared spectroscopy (FTIR), Differential scanning calorimetry (DSC), X-Ray diffraction (X-RD) and Scanning electron microscopy (SEM).The FTIR spectroscopy explains the crosslinking between the CS-PVA. DSC& X-RD indicated the molecular level distribution of Acebutolol HCl drug in the polymer matrix. The SEM of the microspheres suggested the formation of spherical particles. Swelling experiments on the microspheres provided important information on drug diffusion properties. Release data have been analyzed using an empirical equation to understand the nature of transport of drug containing solution through the polymeric matrices. The controlled release characteristic of the matrices for Acebutolol HCl was investigated in pH 7.4 media. The results indicate that the drug was released in a controlled manner up to 10 h.