Nanostructured biosensor to estimate the freshness of fish

Freshness of fish is of importance for consumers because of its connection with health and taste. A mixture of complex volatile biogenic amines collectively known as total volatile basic nitrogen (TVB-N) are released from the fish spoilage due to enzyme-catalyzed decomposition of biogenic amines by spoilage microorganisms. The release of TVB-N, due to microorganism growth in fish samples are considered as potential analytical indicator of fish spoilage. The developed sensor contains a mixture of pH sensitive anionic dye, cresol red (CR) and cationic surfactant cetyltrimethyl ammonium bromide (CTAB) above the critical micellar concentration. The mixture of CR-CTAB (1:1) was immobilized on the reduced graphene oxide (rGO) modified electrode surface. A change in static voltage was observed across the CR-CTAB/rGO biosensor when TVB-N are released from spoiled fish under room temperature. The developed biosensor can be used for the real time measurement of fish freshness

Studies on the effect of temperature on Au Nanoparticles

This work report the temperature dependence UV-Visible (UV-Vis) Spectroscopy, Photoluminescence (PL) spectroscopy, Surface Plasmon Resonance (SPR), current change and electrochemical studies of gold nanoparticles (AuNPs). The UV-Vis, PL, SPR, current and redox potential of AuNPs strongly depends on temperature. The SPR band of AuNPs shows at 534 nm. The PL emission band of AuNPs shows at 421 nm, when excited at 350 nm. The UV-Vis of AuNPs was studied between the temperature range 180-800 C. The PL emission of AuNPs was studied between the temperature range 160-830 C. The observed temperature raise effects the red shift along with broadening of SPR band and PL emission intensity of AuNPs. The redox potential (verses Ag-AgCl reference electrode) of AuNPs was measured by cyclic voltammetry technique between the temperature range12o_80o C. The observed redox potential -0.956Volt at 12oC shifts anodically with raising the temperature to -0.904Volt at 40oC and the redox potential remains unchanged at -0.904Volt up to 80oC. Temperature induced effects on AuNPs appeared between the temperature range 38o-45o C and beyond this temperature range no significant influence of temperature on SPR, PL emission intensity, current change and redox potential were found. The temperature dependent effects may be attributed due to the electron-phonon scattering, thermal expansion of AuNPs