Synthesis and study of aggregation kinetics of fluorescence active N-(1-Naphthyl)ethylenediammonium cations functionalized silver nanoparticles for a chemo-sensor probe

Abstract N -(1-Naphthly)ethylenediammonium cations (NEDA 2 + ) stabilized silver nanoparticles (NEDA-Ag-NPs) were synthesized and explored their potential use for a chemo-sensor probe. The NEDA 2 + cations being fluorescent active make the particles functionalized as well. They physically adsorb (adsorption constant (K ads ), 2.65 × 10 9  M − 1 ) onto the surface of Ag-NPs and make them cationic with zeta potential value of 23 ± 2 mV. TEM image shows that particles are indeed spherical in shape. Monitoring SPR band (extinction coefficient (e), 5.3 × 10 8  M − 1  cm − 1 ) the potencies of particles for sensing pH and citrate anions have been explored. The citrate anions interact with the surface adsorbed NEDA 2 + cations and form association complex, NEDA 2 + ‐‐‐citrate 3‐ , leading aggregation which is a kinetic effect. The aggregation kinetics was thus monitored for evaluating the association constant (K asso ) by studying UV–vis and fluorescence spectroscopic tools. The critical coagulation concentrations (CCC) for both the methods are considered to be the detection limit for citrate anions.