Jai Gopal Sharma

Reduced graphene oxide modified smart conducting paper for cancer biosensor

UNLABELLED We report results of the studies relating to the fabrication of a paper based sensor comprising of poly (3,4-ethylenedioxythiophene):poly(styrenesulfonate) ( PEDOT PSS) and reduced graphene oxide (RGO) composite. The effect of various solvents like methanol, ethylene glycol and H2SO4 on the electrical conductivity of PEDOT PSS coated Whatman paper has been investigated. The conductivity of this solution processed conducting paper significantly increases from ~1.16×10(-4) S cm(-1) up to ~3.57×10(-2) S cm(-1) (~300 times) on treatment with ethylene glycol. The observed significant increase in electrical conductivity is due to conformational rearrangement in the polymer and is due to strong non-covalent cooperative interaction between PEDOT and the cellulose molecules. Further, incorporation of RGO into the conducting paper results in improved electrochemical performance and signal stability. This paper electrode is a promising alternative over the expensive conventional electrodes (ITO, gold and glassy carbon), that are known to have limited application in smart point-of-care (POC) devices. This low cost, flexible and environment friendly conducting paper based biosensor utilized for cancer biomarker (carcinoembryonic antigen, CEA) detection reveals high sensitivity of 25.8 µA ng(-1) mL cm(-2) in the physiological range, 1-10 ng mL(-1).

Nanostructured zirconia decorated reduced graphene oxide based efficient biosensing platform for non-invasive oral cancer detection

We report results of the studies relating to fabrication of a non-invasive, label-free and an efficient biosensing platform for detection of the oral cancer biomarker (CYFRA-21-1). One step hydrothermal process was used for uniform decoration of nanostructured zirconia (average particle size 13 nm) on reduced graphene oxide (ZrO2-RGO) to avoid coagulation of the zirconia nanoparticles and to obtain enhanced electrochemical performance of ZrO2-RGO nanocomposite based biosensor. Further, ZrO2-RGO has been functionalized using 3-aminopropyl triethoxy saline (APTES) and electrophoretically deposited on the indium tin oxide coated glass substrate at a low DC potential.The APTES/ZrO2-RGO/ITO electrode exhibits improved heterogeneous electron transfer (more than two times) with respect to that of the APTES/ZrO2/ITO electrode indicating faster electron transfer kinetics. The -NH2 containing APTES/ZrO2-RGO/ITO platform is further biofunctionalized with anti-CYFRA-21-1. The structural and morphological investigations of the ZrO2-RGO based biosensing platform have been accomplished using X-ray diffraction (XRD), electrochemical, transmission electron microscopy (TEM), atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FT-IR) studies. This immunosensor exhibits a wider linear detection range (2-22 ng mL(-1)), excellent sensitivity (0.756 µA mL ng(-1)) and a remarkable lower detection limit of 0.122 ng mL(-1). The observed results have been validated via enzyme linked immunosorbent assay (ELISA).

A biocompatible serine functionalized nanostructured zirconia based biosensing platform for non-invasive oral cancer detection

We report results of studies relating to the fabrication of nontoxic, biocompatible serine functionalized nanostructured zirconia (serine/nZrO2) for oral cancer detection. The hydrothermally synthesized ZrO2 nanoparticles (∼4.5 nm) have been characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). The cytotoxicity studies of serine/nZrO2 carried out using MTT assay on the HEK 293 human cell line reveal biocompatibility of the serine/nZrO2. The serine functionalized nZrO2 are electrophoretically deposited onto a hydrolysed indium tin oxide (ITO) coated glass electrode (serine/nZrO2/ITO). Furthermore, monoclonal antibodies (anti-CYFRA-21-1) were covalently immobilized onto the serine/nZrO2/ITO electrode and BSA was been used for blocking of the non-specific binding sites. The fabricated BSA/anti-CYFRA-21-1/serine/nZrO2/ITO immunoelectrode was used for label free, non-invasive and efficient detection of an oral cancer biomarker (CYFRA-21-1). The electrochemical response studies of this immunoelectrode exihibited a wider linear detection range (0.01–29 ng mL−1) with a remarkable detection limit (0.01 ng mL−1) and a quick response time (6 min) for detection of the CYFRA-21-1 antigen. The results of validation studies conducted on the fabricated immunoelectrode (BSA/anti-CYFRA-21-1/serine/nZrO2/ITO) using saliva samples of oral cancer patients indicate a good agreement with the results obtained via enzyme linked immunosorbent assay (ELISA).

Molasses-based growth and lipid production by Chlorella pyrenoidosa: A potential feedstock for biodiesel

ABSTRACT Biodiesel provides a feasible solution to the twin crisis of energy security and environmental concerns prevalent today, and it can be extracted from conventional oil crops as well as microalgae. However, lipid productivity in case of microalgae is much higher and has several advantages as compared with crop plants, so it is a better feedstock for biodiesel. In case of Chlorella pyrenoidosa, the heterotrophic cultured cells were found to be better in terms of lipid production, and ultimately biodiesel production, but the bottleneck is that in this mode glucose is used to feed the cells, which amounts to almost 80% of the total cost of biodiesel production. The purpose of this study is to evaluate and highlight the feasibility of using the industrially cheap cane molasses as a carbon source in place of glucose for a large-scale, low-cost lipid production of Chlorella pyrenoidosa. When treated molasses was used as a carbon source instead of glucose, the biomass sharply increases from 0.89 to 1.22 g L–1. On the other hand, the total lipid content increases from 0.27 to 0.66 g g–1. The specific growth rate and yield was higher in treated molasses as compared with that in glucose-supplemented. A mathematical model was also developed based on logistic, Luedeking–Piret, and Luedeking-Piret-like equations. Model predictions were in satisfactory agreement with the measured data, and the mode of lipid production was growth-associated.

An aptasensor for rapid and sensitive detection of estrogen receptor alpha in human breast cancer: AHIRWAR et al.

The analysis of estrogen receptor (ER) expression in breast carcinomas plays a crucial role in determining the endocrine responsiveness of tumors for systemic adjuvant therapy. Conventionally, the ER levels in breast carcinomas had been detected using the dextran-coated charcoal assay and radioimmunoassay, which are now substituted with safer and economic antibody-based assays such as immunohistochemistry (IHC) and enzyme-linked immunosorbent assay (ELISA). Despite a gold (Au) standard method, the IHC has been criticized for factors such as tissue fixation, antibody selection, and threshold staining for result interpretation that could falsify test accuracy and reproducibility. The quest for alternative methods of ER quantification in tissue samples paved the way for aptamer-based diagnostics. Previously, we have isolated a DNA aptamer against human ER alpha (ERα) using an in vitro evolution system. In this study, we developed an electrochemical sensor using the 76-nucleotide DNA ERα- aptamer for rapid, precise, and cost-effective detection of ERα expression in human breast cancer patients. The aptasensor was constructed by covalently immobilizing the thiolated ERα- aptamer onto a screen-printed Au electrode. Construction of aptasensors was confirmed through atomic force microscopy and differential pulse voltammetry measurements. A detection limit of 0.001 ng/ml was calculated for full-length ERα (66.2 kDa) in a detection time of 10 min. Analysis of the cancerous breast tissue samples using the ELISA and aptasensor methods enabled distinctive classification of samples into the categories of ER -ve, weak ER +ve, and strong ER +ve samples. The current change of this aptasensor lies within 5% after a storage of 60 days at 4°C. Further studies on a reasonably large sample size are required to realize the clinical potential of the sensor.

A Simple and Efficient Method for Removal of Phenolic Contaminants in Wastewater Using Covalent Immobilized Horseradish Peroxidase

In the light of the increasing burden of pollutants in major rivers and stringent environmental legislation, adaptation to eco-friendly treatment approaches is desperately required to decontaminate industrial effluents before its discharge to rivers and other fresh water-bodies. In present study, we have designed a simple and efficient method for removal of phenols from effluent wastewater using an immobilized preparation of HRP (horseradish peroxidase). The enzyme was isolated in bulk amount from the roots of the Armoracia rusticana and covalently immobilized to polycarbonate supports using a photolabile linker FNAB (1-fluoro-2-notro-4-azidobenzene). The immobilized enzyme showed enhanced storage stability and reusability. The immobilized HRP was subsequently used for degradation of phenols in sewage and spiked wastewater. The phenol content of spiked wastewater was reduced to 93% in the 3 L reactor following treatment with immobilized HRP and H2O2. The improvement in the quality of water upon treatment was reflected by the changes in pH, conductivity, TDS (total dissolved salts) and biodegradation of organic contents as indicated by 77% and 87% reduction in COD (chemical oxygen demand) and BOD (biochemical oxygen demand) respectively in the analyzed sample.