Encapsulation of silver nanoparticles into the helix of water soluble starch and their sensing properties.

Starch, and silver nitrate were used for one pot facile synthesis of starch capped silver nanoparticles. Transmission electron microscopy (TEM), dynamic light scattering (DLS), iodometry titration, and UV-visible spectroscopy were used for the characterization and encapsulation of silver nanoparticles into the helix of amylose. TEM images confirm that morphology of nanoparticles changed entirely (from spherical and chain-like aggregated to only chain like beautiful silver) in excess of starch concentration. Starch capped nanoparticles were used for detection of hydrogen peroxide. The results reveal that sensing rate of hydrogen peroxide depend on the nature of the scavenger (H₂O₂ > isopropyl alcohol, benzoquinone > tertiary butyl alcohol > potassium iodide). The activation energy = 31 kJ/mol, enthalpy = 28 kJ/mol and entropy = -201 J/K/mol of activation were calculated for the H₂O₂ sensing. Thermogravimetric analysis shows two step thermal degradation of three kind of amylose. KI-I₂ colorimetric method was used to determine of amylose content in potato extract. The antibacterial activity of starch-Ag NPs were estimated against two human pathogens such as Gram positive Staphylococcus aureus MTCC-3160 (S. aureus) and Gram negative Escherichia coli MTCC-450 (E. coli) by using disks diffusion method. Ag NPs have excellent antibacterial activity towards both human strains.