Photo-induced formation of size-selective Ag nanoparticles and their interactions with Escherichia coli

A new synthetic route was utilized for the formation of size-selective Ag nanoparticles (NPs) exploiting UV-irradiation techniques. The one step process exclusively generates Ag NPs of smaller sizes, larger sizes and aggregated nanostructures. The reduction of Ag(I) was done in the presence of adenosine tri-phosphate (ATP) under 30 min of UV-irradiation. ATP served as a dual role, a reducing agent and a stabilizing agent for the formation of Ag NPs. The mechanisms of the particle formation and the effects of different reaction parameters were studied in details. The synthesized particles were stable for more than a month under ambient condition without indication of oxide formation. Moreover, the method did not need any harsh reduction conditions. The synthesized negatively charged ATP–Ag NPs has been mixed with bacteria Escherichia coli and studied their interaction. Finally a comparative study was made with the ATP–Ag NPs with positively charged CTAB–Ag NPs. The results indicated that positively charged Ag NPs deposited better with the bacterium surface compared to the negatively charged. The present research might find important applications for the synthesis of other nanomaterials as well as to understand the interactions of NPs with microorganisms.