Kallayi Nabeela, Reny Thankam Thomas, Jyothi B Nair, Kaustabh Kumar Maiti, Krishna Gopa Kumar Warrier, and Saju Pillai*
ACS Appl. Mater. Interfaces, Just Accepted Manuscript • http://dx.doi.org/10.1021/acsami.6b07295 • Publication Date (Web): 06 Oct 2016
Synthesis of shape-tuned silver (Ag) nanostructures with high plasmon characteristics has drawn significant importance in in-vitro diagnostic applications. Herein, we report a simple aqueous synthetic route using TEMPO-oxidized nanocellulose fibers (T-NCF) and trisodium citrate (TSC) that results in anisotropically grown flower-like Ag nanoconstruct (AgNF). A detailed investigation of the concentration and sequence of the addition of reactants on the formation of these anisotropic Ag structure is presented. Our experimental results show that the mechanism underlying the formation of AgNF is facilitated by the synergistic action of T-NCF and TSC on the directional growth of Ag nuclei during the primary stage which later develop into a flower-like structure by ripening of larger particles consuming smaller Ag particles. As a result the final structure comprises of flower-like morphology over which several smaller Ag particles (of size 4 months) by the efficient capping action of T-NCF. Further, as-synthesized nanoconstruct shows excellent surface enhanced Raman scattering (SERS) activity which enables ultrasensitive detection of para-aminothiophenol (pATP) with a concentration down to 10 aM (10-17 M) in a reproducible way. This bio-supported synthesis of stable aqueous colloids of AgNF may find potential applications as biomedical sensing platform for the trace level detection of analyte molecules.