K. Jayanth Babu

Fabrication of mediator-free hybrid nano-interfaced electrochemical biosensor for monitoring cancer cell proliferation

Glucose, a chief energy source in cellular metabolism, has a significant role in cell proliferation. Cancer cells utilize more glucose than normal cells to meet the energy demand arising due to their uncontrolled proliferation. The present work reports the development of a nano-interfaced amperometric biosensor for rapid and accurate monitoring of glucose utilization by cancer cells. A hybrid nano-interface comprising a blend of carbon nanotubes (CNTs) and graphene (GR) was employed to enhance the surface area of the working electrode and favour direct electron transfer. Glucose oxidase (GOx) immobilized on the interface serves as the sensing element due to its high selectivity and sensitivity towards glucose. Utilization of glucose was monitored at pre-determined time intervals in MiaPaCa-2 cancer cells. The results obtained from the amperometric technique were compared with the values obtained from a commercial glucometer. Alamar blue assay was performed to check the proliferation rate of the cells. A good correlation was obtained between the proliferation rate and glucose utilization. The designed biosensor was found to be unaffected by the presence of potential interferents and hence may serve as a novel in vitro tool to rapidly quantify the proliferation rates of cancer cells in response to different treatment strategies.

Fabrication of Electrochemical Biosensor with ZnO-PVA Nanocomposite Interface for the Detection of Hydrogen Peroxide

Hydrogen peroxide (H2O2) is considered to be highly toxic and its increased concentration in human body may lead to diseases like alzheimers, parkinsons, cardiovascular, tumor and cancer. Hence, there is an increasing demand for the detection of H2O2 in human blood serum. In this context, an electrochemical sensor was developed using zinc oxide-polyvinyl alcohol (ZnO-PVA) nanocomposite as a nano-interface. The fabricated Au/ZnO-PVA/CAT/Chitosan bio-electrode exhibited a well-defined redox peak with anodic and cathodic peak potential of -0.408 V and 0.259 V for Fe(III):Fe(II) and H2O2:1/2 O2 redox couples respectively. The developed biosensor exhibited a linear range of 1 μM-17 μM with a sensitivity of 210.49 μA μM-1 cm-2, response time of less than 1 s, limit of detection of 9.13 nM and a limit of quantification of 30.13 nM. The developed bio-electrode showed a Michaelis-Menten constant (KM) of 0.39 μM and dry stability of 93% up to 20 days. The obtained biosensor was successfully utilized to determine the H2O2 concentration in human blood serum sample.

An electronic Nose for royal delicious apple quality assessment – A tri-layer approach

Foodborne pathogens cause serious health issues and have a strong impact on the economy of the country. In this context, quality testing of royal delicious apple by detecting pathogen contamination using an electronic nose, which contains an array of six ready-made sensors, has been proposed. To estimate the types of pathogens, fresh, half and completely contaminated apple samples were considered for bacterial studies. This study revealed the presence of Staphylococcus, Salmonella and Shigella bacteria, which were in the order of zero, 102, 103-104 CFU/mL. Further, the recorded headspace GC-MS spectra of contaminated samples confirmed the presence of bacterial spoilage markers namely acetone, ethyl acetate, ethyl alcohol and acetaldehyde. Voltage swing of 0.2 and 0.5 V was observed for half and completely contaminated apple samples respectively with reference to the fresh sample. Voltage responses of the sensors fed to Principal component analysis and Wards method of hierarchical cluster algorithms helped to assess the quality of apple samples. By correlating the results of tri-layers namely bacterial count, GCMS data and classification results, reference table was developed and embedded in the ATmega processor of the electronic nose for real-time quality estimation of apple samples.

Characteristics of HT-LiCoO2 cathode films synthesized by Rf magnetron sputtering

Polycrystalline HT-LiCoO2 films were successfully synthesized by rf magnetron sputtering. The films were characterized by the studying their phase, structure, and morphology using ex-situ measurements of X-ray diffractometry (XRD), Raman Spectroscopy, Atomic force micrometry (AFM). Electrochemical performance evaluation indicated that the as grown LiCoO2 films The anodic electrochemical performances of the films have been evaluated by cyclic voltammetry (CV) at a scan rate of 0.5 mV/s and by galvanostatic cycling, with lithium metal as the counter and the reference electrode, and cycled in the range of 3.0 - 4.2 V at a current density of 50 μA/cm2. The films show a discharge capacity at the 20th cycle of 58 μAh cm−2μm− Keywords: LiCoO which exhibited excellent capacity retention with a small capacity fade which exhibited excellent capacity retention with a small capacity fade.