Synthesis of Ag nanoparticles in Span/Span-Tween mixed surfactant system and its optical, kinetic and fluorimetric studies

摘要

Span and Span-Tween mixed surfactants have been used to stabilize the silver nanoparticles synthesized chemically and photochemically. This synthetic process of silver sol preparation has the advantage of producing homogeneous particles of very small size (～1.65 nm) and finally aggregate brilliantly in a symmetric manner to form cubic clusters. Electromagnetic interaction in the close-packed assembly of silver aggregates generates its optical property that has been explained in the light of Maxwell-Gamett effective medium theory. A small sized silver nanoparticle has quenching properties on the fluorophore probes of methylene blue and cresol red. The particle size dependent fluorescence quenching property has been rationalized considering its surface area. Steady state circular dichroism and time resolved spectroscopic studies of Ag nanoparticles with bovine serum albumin (BSA) and human adult hemoglobin (Hb) proves the formation of a ground state BSA-Ag complex. The effect of different sizes of silver nanoparticle on the rate of electron transfer reaction between [Co~(III)(NH3)sBr](NO3)2 and Mohr's salt (Fe~(II)) has also been explained rationally.