A Sensitive Enzymatic Electrochemical Biosensor for Cholesterol Based on Cobalt Ferrite@Molybdenum Disulfide/Gold Nanoparticles.

Cholesterol is essential in biological systems, and the level of cholesterol in the body of a person acts as a diagnostic marker for a variety of diseases. So, in this work, we fabricated an enzymatic electrochemical biosensor for cholesterol using cobalt ferrite@molybdenum disulfide/gold nanoparticles (CoFe2O4@MoS2/Au). The synthesized composite was used for the determination of cholesterol by voltametric methods. The electroactive material CoFe2O4@MoS2/Au was successfully verified from the physiochemical studies such as XRD, Raman, FT-IR, and XPS spectroscopy along with morphological FESEM and HRTEM characterization. CoFe2O4@MoS2/Au showed outstanding dispersion in the aqueous phase, a large effective area, good biological compatibility, and superior electronic conductivity. The microflower-like CoFe2O4@MoS2/Au was confirmed by scanning electron microscopy. The image of transmission electron microscopy showed decoration of gold nanoparticles on CoFe2O4@MoS2 surfaces. Furthermore, a one-step dip-coating technique was used to build the biosensor used for cholesterol detection. In addition to acting as an enabling matrix to immobilize cholesterol oxidase (ChOx), CoFe2O4@MoS2/Au contributes to an increase in electrical conductivity. The differential pulse voltammetry method was used for the quantitative measurement of cholesterol. The calibration curve for cholesterol was linear in the concentration range of 5 to 100 µM, with a low limit of detection of 0.09 µM and sensitivity of 0.194 µA µM-1 cm-2. Furthermore, the biosensor demonstrates good practicability, as it was also employed for identifying cholesterol in real samples with acceptable selectivity and stability.

Synthesis of novel Sn1-xZnxO-chitosan nanocomposites: Structural, morphological and luminescence properties and investigation of antibacterial properties.

In recent times, metal oxide-organic nanocomposites have received great attention because of their feasibility to wide range applications such as super capacitors, antibacterial activity, biomedical sensors, battery applications and microfluidic devices. In this work, zinc oxide-chitosan (ZnO-CS) and their novel tin zinc oxide-chitosan (Sn1-xZnxO-CS) hybrid nanocomposites successfully synthesized by a simple one-pot sol-gel reaction. The equal metal oxide ratio such as 0.5, 1.0, 1.5 and 2.0% (W/V) for zinc and tin sources with constant weight of chitosan were used to prepare the Sn1-xZnxO-CS nanocomposites. Fourier transform infrared spectroscopy results proved the formation of Sn1-xZnxO-CS nanocomposites. X-ray diffraction patterns discovered the mixed phase polycrystalline nature of Sn1-xZnxO-CS nanocomposites. Optical and luminescence properties were extensively studied for nanocomposites by UV-Vis and photoluminescence spectroscopy, respectively. The surface modification elaborately discussed with scanning electron microscope images due to incorporation of SnOx with ZnO-CS matrix. The antibacterial properties of Sn1-xZnxO-CS were tested against Escherichia coli, Salmonella Typhi and Klebseilla Pneumoniae bacterial species.