Annapoorna Mohandas

Chitosan-hyaluronan/nano chondroitin sulfate ternary composite sponges for medical use.

In this work chitosan-hyaluronan composite sponge incorporated with chondroitin sulfate nanoparticle (nCS) was developed. The fabrication of hydrogel was based on simple ionic cross-linking using EDC, followed by lyophilization to obtain the composite sponge. nCS suspension was characterized using DLS and SEM and showed a size range of 100-150 nm. The composite sponges were characterized using SEM, FT-IR and TG-DTA. Porosity, swelling, biodegradation, blood clotting and platelet activation of the prepared sponges were also evaluated. Nanocomposites showed a porosity of 67% and showed enhanced swelling and blood clotting ability. Cytocompatibility and cell adhesion studies of the sponges were done using human dermal fibroblast (HDF) cells and the nanocomposite sponges showed more than 90% viability. Nanocomposite sponges also showed enhanced proliferation of HDF cells within two days of study. These results indicated that this nanocomposite sponges would be a potential candidate for wound dressing.

Chitosan-hyaluronic acid/VEGF loaded fibrin nanoparticles composite sponges for enhancing angiogenesis in wounds.

Reduced levels of endogenous growth factors and diminished angiogenesis are contributory factors for impaired wound healing in diabetic patients. Vascular endothelial growth factor (VEGF) is the most potent angiogenic growth factor which stimulates multiple phases of wound healing angiogenesis and thereby accelerates healing. The aim of this work was to develop chitosan-hyaluronic acid composite sponge incorporated with fibrin nanoparticles loaded with VEGF as a wound dressing for diabetic wounds. VEGF loaded fibrin nanoparticles (150-180 nm) were prepared and characterized which were then incorporated to the composite sponge. The prepared sponges were characterized by SEM and FT-IR. Porosity, swelling, biodegradation, mechanical properties and haemostatic potential of the sponges were also studied. Release of VEGF from the composite sponges was evaluated using ELISA kit. More than 60% of the loaded VEGF was released in three days. Cell viability and attachment studies of the composite sponges were evaluated using human dermal fibroblast (HDF) cells and human umbilical vein endothelial cells (HUVECs). HUVECs seeded on VEGF containing sponges showed capillary like tube formation which was absent in control sponges. The results suggest that the prepared chitosan-hyaluronic acid/VEGF loaded nanofibrin composite sponges (CHVFS) have potential to induce angiogenesis in wound healing.

Antimicrobial Activity of Chitosan-Carbon Nanotube Hydrogels

In the present study, we have prepared chitosan-carbon nanotube (Chitosan-CNT) hydrogels by the freeze-lyophilization method and examined their antimicrobial activity. Different concentrations of CNT were used in the preparation of Chitosan-CNT hydrogels. These differently concentrated CNT hydrogels were chemically characterized using Fourier Transform-Infrared Spectroscopy, Scanning Electron Microscopy and Optical microscopy. The porosity of the hydrogels were found to be >94%. Dispersion of chitosan was observed in the CNT matrix by normal photography and optical microscopy. The addition of CNT in the composite scaffold significantly reduced the water uptake ability. In order to evaluate antimicrobial activity, the serial dilution method was used towards Staphylococcus aureus, Escherichia coli and Candida tropicalis. The composite Chitosan-CNT hydrogel showed greater antimicrobial activity with increasing CNT concentration, suggesting that Chitosan-CNT hydrogel scaffold will be a promising biomaterial in biomedical applications.

Exploration of alginate hydrogel/nano zinc oxide composite bandages for infected wounds

Alginate hydrogel/zinc oxide nanoparticles (nZnO) composite bandage was developed by freeze-dry method from the mixture of nZnO and alginate hydrogel. The developed composite bandage was porous with porosity at a range of 60%–70%. The swelling ratios of the bandages decreased with increasing concentrations of nZnO. The composite bandages with nZnO incorporation showed controlled degradation profile and faster blood clotting ability when compared to the KALTOSTAT® and control bandages without nZnO. The prepared composite bandages exhibited excellent antimicrobial activity against Escherichia coli, Staphylococcus aureus, Candida albicans, and methicillin resistant S. aureus (MRSA). Cytocompatibility evaluation of the prepared composite bandages done on human dermal fibroblast cells by Alamar assay and infiltration studies proved that the bandages have a non-toxic nature at lower concentrations of nZnO whereas slight reduction in viability was seen with increasing nZnO concentrations. The qualitative analysis of ex-vivo re-epithelialization on porcine skin revealed keratinocyte infiltration toward wound area for nZnO alginate bandages.

Electrospun continuous nanofibers based on a TiO2–ZnO–graphene composite

The present study provides the first reports on the electrospinning of TiO2–ZnO–graphene composite nanofibers for photovoltaic and biomedical applications. These nanofibers were characterized by spectroscopic and microscopic techniques to evaluate the morphologies and phases. The fiber diameter was found to be ∼210 nm. The graphene content was maintained in the range of 0.2–0.7 weight percent. It was observed that when the graphene content was increased beyond 0.7 weight percent, the continuous fiber morphology was lost. Raman spectroscopy was used to confirm the presence of graphene. Conductivity studies showed a ∼9 times increase in conductance values for the TiO2–ZnO–graphene system as compared to TiO2–ZnO nanofibers. Employing these TiO2–ZnO–graphene fiber composites as photoanodes in dye sensitized solar cells, an efficiency of 3.7% was attained. Antibacterial studies performed on two bacterial strains, namely E.coli and S. aureus, have shown that these composite fibers can be used effectively for antibacterial wound dressing applications.

Chitosan based metallic nanocomposite scaffolds as antimicrobial wound dressings

Chitosan based nanocomposite scaffolds have attracted wider applications in medicine, in the area of drug delivery, tissue engineering and wound healing. Chitosan matrix incorporated with nanometallic components has immense potential in the area of wound dressings due to its antimicrobial properties. This review focuses on the different combinations of Chitosan metal nanocomposites such as Chitosan/nAg, Chitosan/nAu, Chitosan/nCu, Chitosan/nZnO and Chitosan/nTiO2 towards enhancement of healing or infection control with special reference to the antimicrobial mechanism of action and toxicity.

Drug loaded bi-layered sponge for wound management in hyperfibrinolytic conditions

Excessive bleeding due to premature clot lysis and secondary bacterial wound infection are two significant problems that contribute to increased morbidity in patients with hyperfibrinolytic conditions. In this study, we have developed a bi-layered sponge that promotes fibrin clot stability and prevents secondary bacterial wound infections. Using the technique of freeze-drying, a bi-layer matrix consisting of hyaluronic acid (HA) containing aminocaproic acid (amicar) and chitosan containing tetracycline loaded O-carboxymethyl chitosan nanoparticles (Tet-O-CMC NPs) were produced. We hypothesized that the top chitosan layer with Tet-O-CMC NPs will prevent wound infection and concomitantly act as a matrix for cellular migration and subsequent wound healing, while the amicar-containing layer would promote clot stability. Tet-O-CMC NPs and bi-layer sponges were characterized using Dynamic Light Scattering (DLS), Scanning Electron Microscopy (SEM) and Fourier Transform Infra Red (FT-IR) spectroscopy. Physiochemical characterization such as porosity, swelling and mechanical testing was performed. The drug release study shows that the bi-layered sponge demonstrates a robust burst release of amicar and a sustained release of tetracycline. The ex vivo muscle permeation study indicated that Tet-O-CMC NPs have enhanced tissue permeation compared to free Tet. In vitro antibacterial activity of the bi-layer sponge towards laboratory and clinical strains of Staphylococcus aureus and Escherichia coli was proved. The ex vivo bacterial sensitivity study using porcine muscles confirmed the antibacterial activity, while the cell viability study using human dermal fibroblast (HDF) cells revealed its biocompatible nature. The in vitro antifibrinolytic study shows that the bi-layered sponge with amicar showed significant protection against streptokinase induced clot lysis. These studies suggest that the prepared amicar and tetracycline loaded chitosan-HA bi-layered sponge can be used effectively to promote better wound healing by simultaneously preventing bacterial infection, and enhancing clot stability.

Injectable angiogenic and osteogenic carrageenan nanocomposite hydrogel for bone tissue engineering

Functional biomaterials that couple angiogenesis and osteogenesis processes are vital for bone tissue engineering and bone remodeling. Herein we developed an injectable carrageenan nanocomposite hydrogel incorporated with whitlockite nanoparticles and an angiogenic drug, dimethyloxallylglycine. Synthesized whitlockite nanoparticles and nanocomposite hydrogels were characterized using SEM, TEM, EDS and FTIR. Developed hydrogels were injectable, mechanically stable, cytocompatible and has better protein adsorption. Incorporation of dimethyloxallylglycine resulted in initial burst release followed by sustained release for 7 days. Human umbilical vein endothelial cells exposed to dimethyloxallylglycine incorporated nanocomposite hydrogel showed enhanced cell migration and capillary tube-like structure formation. Osteogenic differentiation in rat adipose derived mesenchymal stem cells after 7 and 14 days revealed increased levels of alkaline phosphatase activity in vitro. Furthermore, cells exposed to nanocomposite hydrogel revealed enhanced protein expressions of RUNX2, COL and OPN. Overall, these results suggest that incorporation of whitlockite and dimethyloxallylglycine in carrageenan hydrogel promoted osteogenesis and angiogenesis in vitro.

Bi-layered nanocomposite bandages for controlling microbial infections and overproduction of matrix metalloproteinase activity

Chronic diabetic wounds is characterised by increased microbial contamination and overproduction of matrix metalloproteases that would degrade the extracellular matrix. A bi-layer bandage was developed, that promotes the inhibition of microbial infections and matrix metalloprotease (MMPs) activity. Bi-layer bandage containing benzalkonium chloride loaded gelatin nanoparticles (BZK GNPs) in chitosan-Hyaluronic acid (HA) as a bottom layer and sodium alendronate containing chitosan as top layer was developed. We hypothesized that the chitosan-gelatin top layer with sodium alendronate could inhibit the MMPs activity, whereas the chitosan-HA bottom layer with BZK GNPs (240±66nm) would enable the elimination of microbes. The porosity, swelling and degradation nature of the prepared Bi-layered bandage was studied. The bottom layer could degrade within 4days whereas the top layer remained upto 7days. The antimicrobial activity of the BZK NPs loaded bandage was determined using normal and clinical strains. Gelatin zymography shows that the proteolytic activity of MMP was inhibited by the bandage.