Vinoth-Kumar Lakshmanan

Flexible and microporous chitosan hydrogel/nano ZnO composite bandages for wound dressing: in vitro and in vivo evaluation.

Current wound dressings have disadvantages such as less flexibility, poor mechanical strength, lack of porosity, and a tendency for dressings to adhere onto the wound surface; in addition, a majority of the dressings did not possess antibacterial activity. Hydrogel-based wound dressings would be helpful to provide a cooling sensation and a moisture environment, as well as act as a barrier to microbes. To overcome these hassles, we have developed flexible and microporous chitosan hydrogel/nano zinc oxide composite bandages (CZBs) via the incorporation of zinc oxide nanoparticles (nZnO) into chitosan hydrogel. The prepared nanocomposite bandages were characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray diffractometry (XRD), and scanning electron microscopy (SEM). In addition, swelling, degradation, blood clotting, antibacterial, cytocompatibility, cell attachment on the material, and cell infiltration into the composite bandages were evaluated. The nanocomposite bandage showed enhanced swelling, blood clotting, and antibacterial activity. Cytocompatibility of the composite bandage has been analyzed in normal human dermal fibroblast cells. Cell attachment and infiltration studies showed that the cells were found attached to the nanocomposite bandages and penetrated into the interior. Furthermore, the in vivo evaluations in Sprague-Dawley rats revealed that these nanocomposite bandages enhanced the wound healing and helped for faster re-epithelialization and collagen deposition. The obtained data strongly encourage the use of these composite bandages for burn wounds, chronic wounds, and diabetic foot ulcers.

Combinatorial anticancer effects of curcumin and 5-fluorouracil loaded thiolated chitosan nanoparticles towards colon cancer treatment

BACKGROUND Evaluation of the combinatorial anticancer effects of curcumin/5-fluorouracil loaded thiolated chitosan nanoparticles (CRC-TCS-NPs/5-FU-TCS-NPs) on colon cancer cells and the analysis of pharmacokinetics and biodistribution of CRC-TCS-NPs/5-FU-TCS-NPs in a mouse model. METHODS CRC-TCS-NPs/5-FU-TCS-NPs were developed by ionic cross-linking. The in vitro combinatorial anticancer effect of the nanomedicine was proven by different assays. Further the pharmacokinetics and biodistribution analyses were performed in Swiss Albino mouse using HPLC. RESULTS The 5-FU-TCS-NPs (size: 150±40nm, zeta potential: +48.2±5mV) and CRC-TCS-NPs (size: 150±20nm, zeta potential: +35.7±3mV) were proven to be compatible with blood. The in vitro drug release studies at pH4.5 and 7.4 showed a sustained release profile over a period of 4 days, where both the systems exhibited a higher release in acidic pH. The in vitro combinatorial anticancer effects in colon cancer (HT29) cells using MTT, live/dead, mitochondrial membrane potential and cell cycle analysis measurements confirmed the enhanced anticancer effects (2.5 to 3 fold). The pharmacokinetic studies confirmed the improved plasma concentrations of 5-FU and CRC up to 72h, unlike bare CRC and 5-FU. CONCLUSIONS To conclude, the combination of 5-FU-TCS-NPs and CRC-TCS-NPs showed enhanced anticancer effects on colon cancer cells in vitro and improved the bioavailability of the drugs in vivo. GENERAL SIGNIFICANCE The enhanced anticancer effects of combinatorial nanomedicine are advantageous in terms of reduction in the dosage of 5-FU, thereby improving the chemotherapeutic efficacy and patient compliance of colorectal cancer cases.

O-carboxymethyl chitosan nanoparticles for metformin delivery to pancreatic cancer cells.

In this work we developed metformin loaded O-carboxymethyl chitosan (O-CMC) nanoparticles (NPs) by ionic-gelation method. The prepared NPs of 240 ± 50 nm size with spherical morphology exhibited a pH sensitive release of metformin in vitro. Cytotoxicity studies showed that the drug-incorporated NPs induced significant toxicity on pancreatic cancer cells (MiaPaCa-2) compared to normal cells (L929). Metformin loaded NPs exhibited nonspecific internalization by normal and pancreatic cancer cells; however metformin released from the NPs induced preferential toxicity on pancreatic cancer cells. Our preliminary studies suggested that such a novel approach could possibly overcome the current limitations of metformin in its clinical application against pancreatic cancer.

In vitro combinatorial anticancer effects of 5-fluorouracil and curcumin loaded N,O-carboxymethyl chitosan nanoparticles toward colon cancer and in vivo pharmacokinetic studies

Colon cancer is the third most leading causes of death due to cancer worldwide and the chemo drug 5-fluorouracils (5-FU) applicability is limited due to its non-specificity, low bioavailability and overdose. The efficacy of 5-FU in colon cancer chemo treatment could be improved by nanoencapsulation and combinatorial approach. In the present study curcumin (CUR), a known anticancer phytochemical, was used in combination with 5-FU and the work focuses on the development of a combinatorial nanomedicine based on 5-FU and CUR in N,O-carboxymethyl chitosan nanoparticles (N,O-CMC NPs). The developed 5-FU-N,O-CMC NPs and CUR-N,O-CMC NPs were found to be blood compatible. The in vitro drug release profile in pH 4.5 and 7.4 showed a sustained release profile over a period of 4 days. The combined exposure of the nanoformulations in colon cancer cells (HT 29) proved the enhanced anticancer effects. In addition, the in vivo pharmacokinetic data in mouse model revealed the improved plasma concentrations of 5-FU and CUR which prolonged up to 72 h unlike the bare drugs. In conclusion, the 5-FU and CUR released from the N,O-CMC NPs produced enhanced anticancer effects in vitro and improved plasma concentrations under in vivo conditions.

Synthesis, characterization and cytocompatibility studies of α-chitin hydrogel/nano hydroxyapatite composite scaffolds

α-chitin hydrogel/nano hydroxyapatite (nHAp) composite scaffold have been synthesized by freeze-drying approach with nHAp and α-chitin hydrogel. The prepared nHAp and nanocomposite scaffolds were characterized using DLS, SEM, FT-IR, XRD and TGA studies. The porosity, swelling, degradation, protein adsorption and biomineralization (calcification) of the prepared nanocomposite scaffolds were evaluated. Cell viability, attachment and proliferation were investigated using MG 63, Vero, NIH 3T3 and nHDF cells to confirm that the nanocomposite scaffolds were cytocompatible and cells were found to attach and spread on the scaffolds. All the results suggested that these scaffolds can be used for bone and wound tissue engineering.

Development and evaluation of 5-fluorouracil loaded chitin nanogels for treatment of skin cancer

This study focuses on development and evaluation of 5-fluorouracil (5-FU) loaded chitin nanogels (FCNGs). It formed good, stable aqueous dispersion with spherical particles in 120-140 nm size range and showed pH responsive swelling and drug release. The FCNGs showed toxicity on melanoma (A375) in a concentration range of 0.4-2.0mg/mL, but less toxicity toward human dermal fibroblast (HDF) cells by MTT assay. Confocal analysis revealed uptake of FCNGs by both cells. From skin permeation experiments, FCNGs showed almost same steady state flux as that of control 5-FU but the retention in the deeper layers of skin was found to be 4-5 times more from FCNGs. Histopathological evaluation revealed loosening of the horny layer of epidermis by interaction of cationically charged chitin, with no observed signs of inflammation and so FCNGs can be a good option for treatment of skin cancers.

Drug delivery and tissue engineering applications of biocompatible pectin-chitin/nano CaCO3 composite scaffolds

In this work, we have developed a nanocomposite scaffold using a mixture of pectin, chitin and nano CaCO3 using the technique of lyophilization, with an intended use towards biomedical applications such as tissue engineering and drug delivery. The prepared composite scaffold was characterized using scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). In addition, swelling, degradation and biomineralization capability of the composite scaffold was evaluated. The developed composite scaffold showed controlled swelling and degradation in comparison with the control scaffold. Cytocompatibility evaluation of the scaffold was tested on NIH3T3, L929 and human dermal fibroblast (HDF) cells, showed negligible toxicity towards cells. Cell attachment and proliferation studies were also conducted using these cells, which showed that cells attached onto the scaffolds and started to proliferate after 48 h of incubation. Further, drug delivery through the scaffold was examined using a bisphosphonate called Fosamax. These results suggest that the developed composite scaffold possess the essential requisites for their application in the fields of tissue engineering and drug delivery.

Chitosan-Based Nanoparticles in Cancer Therapy

In recent years, many nanotechnology platforms in the area of medical biology, including cancer therapy, have attracted remarkable attention. In particular, research in targeted, polymeric nanoparticles for cancer therapy has increased dramatically in the past 5–10 years. However, the potential success of nanoparticles in the clinic relies on consideration of important parameters such as nanoparticle fabrication strategies, their physical properties, drug loading efficiencies, drug release potential, and, most importantly, minimum toxicity of the carrier itself. Recent work has suggested that chitosan materials hold much promise in advancing nanoparticle-based therapeutics. The field of oncology could soon be revolutionized by novel strategies for therapy employing chitosan-based nanotherapeutics. Several aspects of cancer therapy would be involved. Chitosans can also be applied to a variety of cancer therapies to improve their safety and efficacy. Further applications of chitosans in cancer therapy are being examined. This review focuses on providing brief updates on chitosan nanoparticles for cancer therapy.

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.

Chitosan cross-linked docetaxel loaded EGF receptor targeted nanoparticles for lung cancer cells.

Lung cancer, associated with the up-regulated epidermal growth factor receptor (EGFR) led to the development of EGFR targeted anticancer therapeutics. The biopolymeric nanoparticles form an outstanding system for the targeted delivery of therapeutic agents. The present work evaluated the in vitro effects of chitosan cross-linked γ-poly(glutamic acid) (γ-PGA) nanoparticles (Nps) loaded with docetaxel (DTXL) and decorated with Cetuximab (CET), targeted to EGFR over-expressing non-small-cell-lung-cancer (NSCLC) cells (A549). CET-DTXL-γ-PGA Nps was prepared by ionic gelation and CET conjugation via EDC/NHS chemistry. EGFR specificity of targeted Nps was confirmed by the higher uptake rates of EGFR +ve A549 cells compared to that of EGFR -ve cells (NIH3T3). The cytotoxicity of Nps quantified using cell based (MTT/LDH) and flowcytometry (Cell-cycle analysis, Annexin V/PI and JC-1) assays showed superior antiproliferative activity of CET-DTXL-γ-PGA Nps over DTXL-γ-PGA Nps. The A549 cells treated with CET-DTXL-γ-PGA NPs underwent a G2/M phase cell cycle arrest followed by reduction in mitochondrial membrane potential of A549 cells, inducing apoptosis and necrosis resulting in enhanced cancer cell death. CET-DTXL-γ-PGA Nps exhibited enhanced cellular internalization and therapeutic activity, by actively targeting EGFR on NSCLC cells and hence could be an effective alternative to non-specific, conventional chemotherapy by increasing its efficiency by many folds.