Facile biological approach for immobilization, physicochemical characterization and antibacterial activity of noble metals nanocomposites

• The Calcium alginate hydrogel (films) were prepared by gel casting technique.
• AuNPs and AgNPs were immobilized on the hydrogel films using aqueous leaf extract of Cassia auriculata.
• The bio-nanocomposites are biodegradable and thermally stable applicable in biomedical and electronic fields.
• The films found antibacterial against gram positive and gram negative bacteria.
• The procedure is simple, green and cost effective.

The use of biopolymer as template to regulate metallic nanoparticles is promising field in green nanotechnology. We have designed a facile biological way for rapid synthesis and immobilization of gold and silver nanoparticles on alginate films using leaf extract of Cassia auriculata. The prepared gold bio-nanocomposite (Au-BNC) and silver bio-nanocomposite (Ag-BNC) were characterized by UV–vis spectroscopy, Fourier transform infrared spectroscopy, Transmission electron microscopy and Thermal analysis. The bio-nanocomposites exhibited good antibacterial activity against both gram positive (Bacillus subtilis) and gram negative (Escherichia coli) bacteria. The metal nanoparticle embedded films have number of applications in catalysis, optical biosensors, electronic, biomedical devices and environmental remediation.