Jay Singh

Nanostructured nickel oxide-chitosan film for application to cholesterol sensor

Cholesterol oxidase (ChOx) physisorbed onto NiO nanoparticles (nNiO, 22 nm)— chitosan (CHIT) film prepared using coprecipitation method has been characterized using x-ray diffraction, Fourier transform infrared, scanning electron microscopy, cyclic voltammetry, and electrochemical impedance spectroscopy techniques. The results of electrochemical response studies conducted on ChOx/nan-NiO-CHIT/ITO bioelectrode show linearity of 10–400 mg/dl, detection limit of 43.4 mg/dl, sensitivity of 0.808 μA/(mg dl cm2), fast response time of 15 s, and shelf-life of about 10 weeks. The low value of Michaelis–Menten constant (Km) obtained as 0.67 mM indicates high affinity of ChOx toward the substrate.

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.

Ring like self assembled Ni nanoparticles based biosensor for food toxin detection

The self-assembled ring like nickel (RnNi ∼ 10-20 nm) nanoparticles have been prepared by pulsed laser ablation method and confirmed by transmission electron microscopy. These RnNi nanoparticles electrophoretically deposited onto the indium-tin-oxide (ITO) glass substrate have been functionalized with dimethyl sulfoxide (DMSO) for covalent immobilization of anti-aflatoxin (a-AfB1) monoclonal antibodies and bovine serum albumin as blocking agent. The electrochemical response studies of a-AfB1/DMSO/RnNi-film/ITO bioelectrode reveal linearity as 5-100 ngdL−1, detection limit of 32.7 ngdL−1, sensitivity of 0.59 μA/ng dL−1, and shelf-life of 60 days. The low value (1.3 × 1014 molL−1) of association constant (Ka) shows high affinity towards aflatoxin.

Recent advances in mycotoxins detection

Mycotoxins contamination in both food and feed is inevitable. Mycotoxin toxicity in foodstuff can occur at very low concentrations necessitating early availability of sensitive and reliable methods for their detection. The present research thrust is towards the development of a user friendly biosensor for mycotoxin detection at both academic and industrial levels to replace conventional expensive chromatographic and ELISA techniques. This review critically analyzes the recent research trend towards the construction of immunosensor, aptasensor, enzymatic sensors and others for mycotoxin detection with a reference to label and label free methods, synthesis of new materials including nano dimension, and transuding techniques. Technological aspects in the development of biosensors for mycotoxin detection, current challenges and future prospects are also included to provide a overview and suggestions for future research directions.

Preparation and properties of hybrid monodispersed magnetic α-Fe2O3 based chitosan nanocomposite film for industrial and biomedical applications

In this study, hydrothermally prepared magnetic α-Fe2O3 nanoparticles were dispersed in chitosan (CH) solution to fabricate nanocomposite film. X-ray diffraction (XRD) patterns indicated that the α-Fe2O3 nanoparticles were pure α-Fe2O3 with rhombohedral structures, and the fabrication of CH did not result in a phase change. The scanning electron microscopy (SEM) and transmission electron microscope (TEM) results showed that the hexagonal and spherical monodispersed α-Fe2O3 nanoparticles were encapsulated into the spherical dumb shaped CH-α-Fe2O3 nanocomposite film with a mean diameter of ∼87 and ∼110 nm respectively. The α-Fe2O3 nanoparticles and CH-α-Fe2O3 nanocomposite film were also characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and vibrating sample magnetometer (VSM). Magnetic measurements revealed that the saturated magnetization (Ms) and remanent magnetization (Mr) of the pure α-Fe2O3 nanoparticles reached 0.573 emu/g and 0.100 emu/g respectively and the nanoparticles showed the characteristics of weak ferromagnetic before and after coating with CH.

Bienzyme-Functionalized Monodispersed Biocompatible Cuprous Oxide/Chitosan Nanocomposite Platform for Biomedical Application

The ultrafine monodispersed cuprous oxide (Ufm-Cu(2)O) nanoparticles have been successfully synthesized by a facile wet chemical method using poly-N-vinylpyrrolidone (PVP) as a capping agent. This colloidal solution of Ufm-Cu(2)O and chitosan (CS) is electrophoretically deposited (EPD) onto the indium tin-oxide (ITO) glass substrate. Thus synthesized nanocomposite has been characterized by X-ray powder diffraction (XRD, ∼6 nm), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier transform infrared (FTIR) spectroscopic techniques. This novel biomedical nanocomposite platform has been explored to fabricate a cholesterol biosensor by immobilizing cholesterol esterase (ChEt) and cholesterol oxidase (ChOx) onto Ufm-Cu(2)O-CS/ITO electrode surface. The seed germination tests of these biomaterials (Ufm-Cu(2)O-CS nanocomposite and ChOx-ChEtUfm-CuO(2)-CS nanobiocomposite), conducted using the disc diffusion method, reveal strong activity against the common pathogens and crops, indicating biocompatibility of the nanocomposite. Under optimized conditions, the linearity between the current response and the cholesterol concentration has been obtained in the range of 10-450 mg/dL, with detection limit of 15.9 mg/dL cm(-2) and a high sensitivity of 0.895 μA/(mg/dL cm(-2)). The proposed biocompatible ChEt-ChOx/Ufm-Cu(2)O-CS/ITO bioelectrode shows fast response time (<5 s), good reproducibility, and long-term stability. This biocompatible biosensor has been used to determine the total cholesterol levels in human serum samples. Investigated antimicrobial activities of bienzyme-functionalized Ufm-Cu(2)O-CS nanocomposite are the potential platform for biomedical applications.

Preparation, circular dichroism induced helical conformation and optical property of chitosan acid salt complexes for biomedical applications.

The efficient procedure for preparation of chitosan acid complexes containing aspartic acid, benzilic acid and terephthalic acid moieties in isopropyl alcohol under mild condition has been demonstrated. The ionic complexation between chitosan and the acid is confirmed by FTIR and 1H NMR spectroscopy. The circular dichroism (CD) spectra of chitosan/aspartic acid complex showed negative (at lambda=312) band, chitosan/benzilic acid and chitosan/terephthalic complexes showed positive (at lambda=286 and 315 nm) band in DMSO, indicating that the polymers adopted helical (left-handed and last two right-handed) secondary structure. The inversion of the CD pattern in chitosan acid salt complexes suggests that there is a change in the chiral structure of the polymer system. Some physical properties and surface morphology were analyzed by X-ray diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetry (TG) and scanning electron microscopy (SEM). Optical properties of chitosan derivatives are evaluated by photoluminescence (PL) spectroscopy which showed red shift. The introduction of acid moieties into chitosan increases the solubility in most of the organic solvents, which opens new perspectives for the employment of chitosan-based biohybrid in biomedical applications.

A highly efficient rare earth metal oxide nanorods based platform for aflatoxin detection

The nanostructured rare earth metal oxide (samarium oxide, n-Sm2O3) nanorods, prepared using a forced hydrolysis technique, have been electrophoretically deposited (EPD) onto an indium-tin-oxide (ITO) glass substrate. This novel platform has been utilized for co-immobilization of monoclonal antibodies of aflatoxin B1 (Ab-AFB1) and bovine serum albumin (BSA) via electrostatic interactions for food toxin (AFB1) detection. Thus prepared n-Sm2O3 nanorods have been characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopic techniques. The results of electrochemical response studies of the BSA/Ab-AFB1/n-Sm2O3/ITO immunoelectrode obtained as a function of aflatoxin concentration reveal a linearity of 10-700 pg mL-1, a detection limit of 57.82 pg mL-1 cm-2, a response time of 5 s and a sensitivity of 48.39 μA pg-1 mL-1 cm-2 with a regression coefficient of 0.961. The association constant (Ka) for antigen-antibody interactions obtained is 47.9 pg mL-1, which indicates high affinity of antibodies towards the antigen (AFB1). The application of n-Sm2O3 modified electrode for immunosensor analysis offers a novel platform and efficient strategy for the application of rare earth metal oxide materials in bioelectronics.

Preparation, Antibacterial and Physicochemical Behavior of Chitosan/Ofloxacin Complexes

A novel chitosan derivative with ofloxacin (OFX) has been successfully prepared. The IR and 1H-NMR results revealed that the chitosan/ofloxacin (CH-OFX) complex exhibited an electrostatic interaction. The crystalline and surface morphology were analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The antimicrobial activity of the complexes against various micro-organisms viz. Escherichia coli, Bacillus subtilis, Pseudomonas aeruginosa and Staphylococcus aureus was tested. It was established that their antibacterial activity is up to four times greater than that of free quinolone drug and chitosan, probably due to the conjunction of favorable pharmacokinetics, excellent bacterial susceptibility and good stability towards metabolic degradation.

Improved production of reducing sugars from rice straw using crude cellulase activated with Fe3O4/alginate nanocomposite.

Effect of Fe3O4 nanoparticles (NPs) and Fe3O4/Alginate nanocomposites (NCs) have been investigated on production and thermostability of crude cellulase enzyme system obtained by newly isolated thermotolerant Aspergillus fumigatus AA001. Fe3O4 NPs and Fe3O4/Alginate NCs have been synthesized by co-precipitation method and characterized through various techniques. In presence of Fe3O4 NPs and Fe3O4/Alginate NCs, filter paper activity of crude cellulase was increased about 35% and 40%, respectively in 72 h as compared to control. Fe3O4/Alginate NCs treated crude enzyme was thermally stable up to 8h at 70°C and retained 56% of its relative activity whereas; control samples could retain only 19%. Further, the hydrolysis of 1.0% alkali treated rice straw using Fe3O4/Alginate NCs treated cellulase gave much higher sugar productivity than control at optimal condition. These findings may be utilized in the area of biofuels and biowaste management.