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TEMPO-Oxidized Nanocellulose Fiber-Directed Stable Aqueous Suspension of Plasmonic Flower-like Silver Nanoconstructs for Ultra-Trace Detection of Analytes
Version 2 2016-10-21, 17:35
Version 1 2016-10-18, 16:24
journal contribution
posted on 2016-10-06, 00:00 authored by Kallayi Nabeela, Reny Thankam Thomas, Jyothi
B. Nair, Kaustabh Kumar Maiti, Krishna Gopa Kumar Warrier, Saju PillaiThe synthesis of
shape-tuned silver (Ag) nanostructures with high plasmon characteristics
has become of significant importance in in vitro diagnostic applications.
Herein, we report a simple aqueous synthetic route using 2,2,6,6-tetramethylpiperidine-1-oxyl-oxidized
nanocellulose fibers (T-NCFs) and trisodium citrate (TSC) that results
in anisotropically grown flower-like Ag nanoconstructs (AgNFs). A
detailed investigation of the concentration and sequence of the addition
of reactants in the formation of these anisotropic Ag structures is
presented. Our experimental results show that the mechanism underlying
the formation of AgNFs is facilitated by the synergistic action of
T-NCFs and TSC on the directional growth of Ag nuclei during the primary
stage, which later develop into a flower-like structure by the ripening
of larger particles consuming smaller Ag particles. As a result the
final structure comprises flower-like morphology over which several
smaller Ag particles (of size <10 nm) are adhered. The aqueous
AgNF colloid exhibits high stability (ζ = −69.4 mV) and
long shelf-life at neutral pH (>4 months) by the efficient capping
action of T-NCFs. Further, an as-synthesized nanoconstructs shows
excellent surface-enhanced Raman scattering activity, which enables
ultrasensitive detection of p-aminothiophenol with
a concentration down to 10 aM (10–17 M) in a reproducible
way. This biosupported synthesis of stable aqueous colloids of AgNF
may find potential applications as a biomedical sensing platform for
the trace level detection of analyte molecules.