SYNTHESIS OF QUASI-SPHERICAL SILVER NANOPARTICLES BY CHEMICAL REDUCTION ROUTE USING DIFFERENT REDUCING AGENTS

Abstract

Silver nanoparticles (AgNPs) have a great potential for molecular detection applications such as surface enhanced Raman spectroscopy (SERS) thanks to their surface plasmon resonance (SPR) property. SPR of AgNPs are closely related to the size, size distribution, aggregation state and shape of these particles. Therefore, in order to obtain optimum enhancement of SERS signals, it is crucial to be able to synthesize AgNPs with controllable size and shape. In this study, AgNPs were synthesized by chemical reduction method using three different reducing agents: trisodium citrate (TSC), ascorbic acid (AA) and hydroxylamine hydrochloride (HH). The synthesized AgNPs were compared in terms of their particle shape, size, size distribution and aggregation state. Accordingly, using 34 mM TSC as a reducing agent resulted in mostly quasi-spherical nanoparticles with an average size of 71.6  20.9 nm. However, some nanorods and triangular nanoparticles were also observed in this sample. In case of using HH as reducing agent, the addition sequence of chemicals into the reaction mixture affected the size and the aggregation state of AgNPs significantly. A bimodal size distribution of mostly quasi-spherical nanoparticles with average sizes of 8.1  4.1 and 60.1  21.5 nm were obtained when HH/NaOH solution was added to AgNO3. When AA was used as a reducing agent, relatively larger quasi-spherical AgNPs with a lower polydispersity and an average size of 78.0  22.2 nm were synthesized.