K.T. Shalumon

Sodium alginate/poly(vinyl alcohol)/nano ZnO composite nanofibers for antibacterial wound dressings

Sodium alginate (SA)/poly (vinyl alcohol) (PVA) fibrous mats were prepared by electrospinning technique. ZnO nanoparticles of size ∼160nm was synthesized and characterized by UV spectroscopy, dynamic light scattering (DLS), XRD and infrared spectroscopy (IR). SA/PVA electrospinning was further carried out with ZnO with different concentrations (0.5, 1, 2 and 5%) to get SA/PVA/ZnO composite nanofibers. The prepared composite nanofibers were characterized using FT-IR, XRD, TGA and SEM studies. Cytotoxicity studies performed to examine the cytocompatibility of bare and composite SA/PVA fibers indicate that those with 0.5 and 1% ZnO concentrations are less toxic where as those with higher concentrations of ZnO is toxic in nature. Cell adhesion potential of this mats were further proved by studying with L929 cells for different time intervals. Antibacterial activity of SA/PVA/ZnO mats were examined with two different bacteria strains; Staphylococcus aureus and Escherichia coli, and found that SA/PVA/ZnO mats shows antibacterial activity due to the presence of ZnO. Our results suggest that this could be an ideal biomaterial for wound dressing applications once the optimal concentration of ZnO which will give least toxicity while providing maximum antibacterial activity is identified.f.

Wet chemical synthesis of chitosan hydrogel–hydroxyapatite composite membranes for tissue engineering applications

Chitosan, a deacetylated derivative of chitin is a commonly studied biomaterial for tissue-engineering applications due to its biocompatibility, biodegradability, low toxicity, antibacterial activity, wound healing ability and haemostatic properties. However, chitosan has poor mechanical strength due to which its applications in orthopedics are limited. Hydroxyapatite (HAp) is a natural inorganic component of bone and teeth and has mechanical strength and osteoconductive property. In this work, HAp was deposited on the surface of chitosan hydrogel membranes by a wet chemical synthesis method by alternatively soaking the membranes in CaCl(2) (pH 7.4) and Na(2)HPO(4) solutions for different time intervals. These chitosan hydrogel-HAp membranes were characterized using SEM, AFM, EDS, FT-IR and XRD analyses. MTT assay was done to evaluate the biocompatibility of these membranes using MG-63 osteosarcoma cells. The biocompatibility studies suggest that chitosan hydrogel-HAp composite membranes can be useful for tissue-engineering applications.

Preparation and characterization of novel β-chitin-hydroxyapatite composite membranes for tissue engineering applications

Beta-chitin is a biopolymer principally found in shells of squid pen. It has the properties of biodegradability, biocompatibility, chemical inertness, wound healing, antibacterial and anti-inflammatory activities. Hydroxyapatite (HAp) is a natural inorganic component of bone and teeth and has osteoconductive property. In this work, beta-chitin-HAp composite membranes were prepared by alternate soaking of beta-chitin membranes in CaCl2 (pH 7.4) and Na2HPO4 solutions for 2 h in each solution. After 1, 3 and 5 cycles of immersion, beta-chitin membranes were characterized using the SEM, FT-IR, EDS and XRD analyses. The results showed the presence of apatite layer on surface of beta-chitin membranes, and the amounts of size and deposition of apatite layers were increased with increasing number of immersion cycles. Human mesenchymal stem cells (hMSCs) were used for evaluation of the biocompatibility of pristine as well as composite membranes for tissue engineering applications. The presence of apatite layers on the surface of beta-chitin membranes increased the cell attachment and spreading suggesting that beta-chitin-HAp composite membranes can be used for tissue engineering applications.

Preparation of silver nanoparticles incorporated electrospun polyurethane nano-fibrous mat for wound dressing

Polyurethane foam is currently used as an exudate absorptive wound dressing material. In this study silver (Ag) nanoparticles were incorporated into electrospun polyurethane (PU) nanofiber to enhance the antibacterial as well as wound healing properties. The electrospinning parameters were optimized for PU with and without silver nanoparticles. Silver nanoparticles were synthesized by aqueous and organic methods. The water absorption, antibacterial and cytocompatibility of the PU-Ag nanofibers were studied and compared to that of conventional PU foam. The results indicated that the PU-Ag nanofibers could be used for wound dressing applications.

Bioactive and osteoblast cell attachment studies of novel α- and β-chitin membranes for tissue-engineering applications

Chitin is a novel biopolymer and has excellent biological properties such as biodegradation in the human body and biocompatible, bioabsorable, antibacterial and wound healing activities. In this work, alpha- and beta-chitin membranes were prepared using alpha- and beta-chitin hydrogel. The bioactivity studies were carried out using these chitin membranes with the simulated body fluid solution (SBF) for 7, 14 and 21 days. After 7, 14 and 21 days the membranes were characterized using SEM, EDS and FT-IR. The SEM, EDS and FT-IR studies confirmed the formation of calcium phosphate layer on the surface of the both chitin membranes. These results indicate that the prepared chitin membranes were bioactive. Cell adhesion studies were also carried out using MG-63 osteoblast-like cells. The cells were adhered and spread over the membrane after 24h of incubation. These results indicated that the chitin membranes could be used for tissue-engineering applications.

Preparation, Characterization and Cell Attachment Studies of Electrospun Multi-scale Poly(caprolactone) Fibrous Scaffolds for Tissue Engineering

Electrospun nano, micro and micro/nano (multiscale) poly(caprolactone) (PCL) fibrous scaffolds with and without nano hydroxyapatite (nHAp) was prepared. All the scaffolds were evaluated for its spectroscopic, morphological, mechanical, thermal, cell attachment and protein adsorption properties. The cell attachment studies showed that cell activity on the nano-fibrous, as well as multi-scale scaffolds with and without nHAp was higher compared to micro-fibrous scaffolds. A time dependent cell attachment study on aligned micro-fibers was carried out to elucidate the difference in cell interaction on micro-fibers. The cell activity, proliferation and total protein adsorption on the nano-fibers/nano-fibers with nHAp was significantly higher than on the micro-fibers, although the adsorption per unit area was less on the nano-fibers due to the much higher surface area of nano-fibers. These results suggest that a combination of a micro- and nano-fiber hierarchical scaffold could be more beneficial for tissue engineering applications than the individual scaffolds provided the amount of nano- fibers could be suitably optimized.

Preparation of Budesonide-Loaded Polycaprolactone Nanobeads by Electrospraying for Controlled Drug Release

Corticosteroids such as budesonide are the drugs of choice for the treatment of inflammatory disorders with an inherent limitation, viz., rapid elimination. To overcome this constraint and attain sustained release, budesonide was encapsulated in a biodegradable polymer, polycaprolactone (PCL), by DC electrospraying. By varying the experimental parameters involved in electrospraying such as applied voltage, flow rate, viscosity as well as conductivity of the polymer solution, the dimensionality of nanostructures was tuned from 1-D nanofibers to spherical nanoparticles. By adopting this rapid and viable method of DC electrospraying, we successfully prepared aqueous suspensions of nearly monodispersed, nano-sized drug encapsulated PCL. Drug encapsulation efficiency, in vitro drug release as well as biocompatibility studies of budesonide-loaded PCL nanobeads were carried out. The cytocompatible nanobeads prepared by electrospraying exhibited good encapsulation efficiency (approx. 75%), with controlled drug release enabled by the dissolution of the polymer. Our results demonstrate the potential of this novel technique of electrospraying in developing efficient drug encapsulated polymeric nanocarriers possessing sustained drug release profile.

Preparation, characterization, bioactive and cell attachment studies of α-chitin/gelatin composite membranes

The chitin/gelatin composite membranes were prepared by mixing of chitin hydrogel with gelatin. The prepared composite membranes were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), mechanical, swelling, enzymatic degradation and thermal studies. The XRD pattern of the chitin/gelatin composite membranes showed almost the same pattern as alpha-chitin. The bioactivity studies of these chitin/gelatin membranes were carried out with the simulated body fluid solution (SBF) for 7, 14 and 21 days followed by the characterization with the scanning electron microscopy (SEM) and Energy Dispersive Spectrum (EDS) studies. The SEM and EDS studies confirmed the formation of calcium phosphate layer on the surface of chitin/gelatin membranes. Biocompatibility of the chitin/gelatin membrane was assessed using human MG-63 osteoblast-like cells. After 48 h of incubation, it was found that the cells had attached and completely covered the membrane surface. Thus, the prepared chitin/gelatin membranes are bioactive and are suitable for cell adhesion suggesting that these membranes can be used for tissue-engineering applications.

Fabrication of three-dimensional nano, micro and micro/nano scaffolds of porous poly(lactic acid) by electrospinning and comparison of cell infiltration by Z-stacking/three-dimensional projection technique

The use of electrospun extracellular matrix (ECM)-mimicking nanofibrous scaffolds for tissue engineering is limited by poor cellular infiltration. The authors hypothesised that cell penetration could be enhanced in scaffolds by using a hierarchical structure where nano fibres are combined with micron-scale fibres while preserving the overall scaffold architecture. To assess this, we fabricated electrospun porous poly(lactic acid) (PLA) scaffolds having nanoscale, microscale and combined micro/nano architecture and evaluated the structural characteristics and biological response in detail. Although the bioactivity was intermediate to that for nanofibre and microfibre scaffold, a unique result of this study was that the micro/nano combined fibrous scaffold showed improved cell infiltration and distribution than the nanofibrous scaffold. Although the cells were found to be lining the scaffold periphery in the case of nanofibrous scaffold, micro/nano scaffolds had cells dispersed throughout the scaffold. Further, as expected, the addition of nanoparticles of hydroxyapatite (nHAp) improved the bioactivity, although it did not play a significant role in cell penetration. Thus, this strategy of creating a three-dimensional (3D) micro/nano architecture that would increase the porosity of the fibrous scaffold and thereby improving the cell penetration, can be utilised for the generation of functional tissue engineered constructs in vitro.

Poly (lactic acid)-chitosan-collagen composite nanofibers as substrates for blood outgrowth endothelial cells.

In this work, the attachment, viability and functionality of rat Blood Outgrowth Endothelial Cells (rBOEC) and genetically modified rBOEC (rBOEC/eNOS-GFP), which over express endothelial nitric oxide synthase (eNOS), were investigated on Poly(lactic acid) (PLA)-chitosan and PLA-chitosan-collagen nanofibrous scaffolds. Both the cell types displayed good attachment, remained viable and functional on both scaffolds. Moreover, incorporation of collagen in the scaffold helped in sustaining the rBOEC for upto one week, although collagen was not found necessary for rBOEC/eNOS-GFP. We conclude that PLA-chitosan based nanofibrous scaffolds can be a potential candidate for BOEC based wound healing applications.