R.P. Tewari

Biomedical applications of carboxymethyl chitosans

This review outlines the recent developments on carboxymethyl chitosan-based bio-medical applications. Carboxymethyl chitosan, a water soluble derivative of chitosan, with enhanced biological and physicochemical properties compared to chitosan, has emerged as a promising candidate for different biomedical applications. Introducing small chemical groups like carboxymethyl to the chitosan structure can drastically increase the solubility of chitosan at neutral and alkaline pH values without affecting their characteristic properties. Due to improved biocompatibility, high moisture retention ability more viscosity and enhanced antimicrobial property of carboxymethyl chitosan than chitosan makes it promising candidate for hydrogels and wound healing applications. The biodegradability and biocompatibility of carboxymethyl chitosan has significant interest with application as biomaterial for tissue engineering. Apart from this, the easy of carboxymethyl chitosan can be easily processed into nanoparticles so it has shown promise for drug delivery, bioimaging, biosensors and gene therapy applications. The contribution of carboxymethyl chitosan to green chemistry in the recent years has also been given in detail. This review will focus on preparative methods and physicochemical and biological properties of carboxymethyl chitosan with particular emphasis on biomedical and pharmaceutical applications of this derivative of chitosan.

The implications of recent advances in carboxymethyl chitosan based targeted drug delivery and tissue engineering applications

Over the last decade carboxymethyl chitosan (CMCS) has emerged as a promising biopolymer for the development of new drug delivery systems and improved scaffolds along with other tissue engineering devices for regenerative medicine that is currently one of the most rapidly growing fields in the life sciences. CMCS is amphiprotic ether, derived from chitosan, exhibiting enhanced aqueous solubility, excellent biocompatibility, controllable biodegradability, osteogenesis ability and numerous other outstanding physicochemical and biological properties. More strikingly, it can load hydrophobic drugs and displays strong bioactivity which highlight its suitability and extensive usage for preparing different drug delivery and tissue engineering formulations respectively. This review provides a comprehensive introduction to various types of CMCS based formulations for delivery of therapeutic agents and tissue regeneration and further describes their preparation procedures and applications in different tissues/organs. Detailed information of CMCS based nano/micro systems for targeted delivery of drugs with emphasis on cancer specific and organ specific drug delivery have been described. Further, we have discussed various CMCS based tissue engineering biomaterials along with their preparation procedures and applications in different tissues/organs. The article then, gives a brief account of therapy combining drug delivery and tissue engineering. Finally, identification of major challenges and opportunities for current and ongoing application of CMCS based systems in the field are summarised.

In situ grafted nanostructured ZnO/carboxymethyl cellulose nanocomposites for efficient delivery of curcumin to cancer

In this present manuscript, zinc oxide (ZnO) nanoparticles embedded carboxymethyl cellulose (CMC) bionanocomposite were prepared by in situ grafting and the hydrophobic anticancer drug curcumin (Cur) was loaded into it. Structural, morphological, and physiochemical behavior of prepared curcumin-loaded CMC/ZnO nanocomposites (NCs) were characterized by FTIR, XRD, SEM, TEM, TGA, and DTA. The drug entrapment efficiency was evaluated and the in vitro efficacy as anticancer drug delivery vehicle was analyzed. The potential toxicity of curcumin-loaded ZnO/CMC NCs (Cur/ZnO/CMC NCs) was studied by using L929 and MA104 cell lines via MTT assay. The cellular uptake study of Cur/ZnO/CMC NCs by normal (L929) and cancer (MA104) cells carried out by using ethanol extraction and by FACS analysis has been reported. The results of this investigation demonstrate that the nanomatrix synthesized can effectively deliver the anticancer drug curcumin, and hence appears to be a promising nanoformulation for anticancer therapy and other biomedical applications.

Application of polymer nanocomposites in the nanomedicine landscape: envisaging strategies to combat implant associated infections

This review article presents an overview of the potential biomedical application of polymer nanocomposites arising from different chemistries, compositions, and constructions. The interaction between the chosen matrix and the filler is of critical importance. The existing polymer used in the biomedical arena includes aliphatic polyesters such as polylactide (PLA), poly(∊-caprolactone) (PCL), poly(p-dioxanone) (PPDO), poly(butylenes succinate) (PBS), poly(hydroxyalkanoate)s, and natural biopolymers such as starch, cellulose, chitin, chitosan, lignin, and proteins. The nanosized fillers utilized to fabricate the nanocomposites are inorganic, organic, and metal particles such as clays, magnetites, hydroxyapatite, nanotubes chitin whiskers, lignin, cellulose, Au, Ag, Cu, etc. These nanomaterials are taking root in a variety of diverse healthcare applications in the sector of nanomedicine including the domain of medical implants and devices. Despite sterilization and aseptic procedures the use of these biomedical devices and prosthesis to improve the patients ‘quality of life’ is facing a major impediment because of bacterial colonization causing nosocomial infection, together with the multi-drug-resistant ‘super-bugs’ posing a serious threat to its utility. This paper discusses the current efforts and key research challenges in the development of self-sterilizing nanocomposite biomaterials for potential application in this area.

Trajectory planning for all sub phases of gait cycle for human-like walking

This paper presents a cubic spline trajectory for all phases of gait cycle to achieve smooth human-like walking. We first characterise the human walking cycle into various sub-phases. A biped robot having seven links and six revolute joints has active hip, knee and ankle joints of both legs for human legs like appearance and walking performance. A mathematical cubic spline is developed for each phase of gait cycle. It uses the experimental flexion angle and velocity data of three joint movements i.e., hip, knee and ankle. The desired trajectory is developed as in case of normal human walking. The proposed trajectory has a standard deviation of less than 1°.

Hybrid control strategy for robotic leg prosthesis using artificial gait synthesis

This paper presents a hybrid control strategy for robotic leg prosthesis. We first synthesise an artificial gait based on human data. A mathematical dynamic model of robotic leg having three degree of freedom, i.e., one each at hip, knee and ankle joint is developed here. Since the dynamics of leg is a highly complex and nonlinear system, radial basis neural network is trained offline for inverse dynamics of leg and is used as a part of control strategy. The simulation environment contains a model of the robotic leg dynamics, a subsystem for artificial gait synthesis, three independent neural network and PD controllers to control the movements of three joints separately in order to achieve the level walking. The simulation work is carried out in Matlab 6.5 and Simulink 5.0. The results showed that the gait of the prosthetic leg can be controlled to a near normal one for level walking.

Quintic polynomial trajectory of biped robot for human-like walking

This paper proposes a separate quintic polynomial trajectory for each sub phase of gait cycle to achieve smooth human-like walking. A biped robot with active hip, knee and ankle joints is considered here for human legs like appearance and walking performance. Trajectory planning is done on the basis of experimental flexion angle, velocity and acceleration data of three joint movements i.e. hip, knee and ankle in sagittal plane. The results are compared with cubic spline trajectory and other results available for gait generation. The result shows that the proposed trajectory can be used for walking of biped robot just like human walking.

An optimal control of bio-robotic leg for human-like walking

This paper presents an optimal control of bio-robotic leg for human-like walking. A mathematical dynamic model of bio-robotic leg having three links i.e. thigh, shank and foot is considered here. The Lagrange-Euler formulation is used to obtain the dynamic equations of motion for calculating torques at various joints of bio-robotic leg. Polynomial trajectory used as desired trajectory is based on gait cycle of human walking data. The results showed that the proposed optimal controller can be used to control level walking of a bio-robotic leg just like human even with bounded uncertainties. This study will help to improve the quality of life of physically challenged human subject with bio-robotic leg for level walking as well as walking over uneven surfaces and uncertain environmental conditions.

Coating Made from Pseudotsuga menziesii Phytosynthesized Silver Nanoparticles is Efficient Against Staphylococcus aureus Biofilm Formation

In this nano era, biomaterials associated infection is a serious problem in the biomedical arena. The race between microbial adhesion and tissue integration becomes a major cause of concern, during the implantation process. Microbial adhesion further gives rise to biofilm formation which finally leads to implant failure. We have therefore designed a strategy to fight effectively against the encroachment of Staphylococcus aureus biofilm, which is chiefly responsible for majority of biomaterials associated infections. Silver nanoparticles have been synthesized for the purpose using foliage needles of the plant Pseudotsuga menziesii, our Christmas tree. Thereafter the nanoparticles were dispersed in chitosan, a biopolymer matrix and a bionanocomposite, self-sterilizing coating biomaterial was developed. The silver nanoparticles produced, the bionanocomposite developed, and the coating over medical implant, have been characterized through various techniques. The efficacy of the silver/chitosan bionanocomposite, against S. aureus biofilm has been studied here, after being coated over medical implant. It was found that coating of medical implants with this material can definitely restrict bacterial adhesion and their subsequent biofilm formation. This biomaterial was found to be blood and biocompatible at specific levels through testing.

Rudraksha Assisted Generation of Silver Nanoparticles for Integrated Application in the Biomedical Landscape

ABSTRACT Today, there is a call for environmentally-friendly, cost-effective technique to eliminate the use of harsh, toxic reagents and minimize hazardous by-products. We thus allocated to synthesize silver nanoparticles through a green route graced with the mystical properties of five faceted beads of the plant Elaeocarpus granitrus Roxb., the Rudraksha. Positive feature of the Rudraksha bead is that it does not degrade, degenerate, or disintegrate; the same bead can be repeatedly intervened for flabbergasting generation of nanoparticles umpteen times bestowing approximately similar results. The nanoparticles were involved for development of bionanocomposite using chitosan matrix. Various techniques were used for characterization. Antimicrobial assay was completed.