Effect of surface charge of gold nanoparticles on fluorescence amplification of polydiacetylene-based liposomes

Abstract

Polydiacetylene (PDA)-based liposome have been attractive as sensory platforms owing to their applicability in simultaneous detection of colorimetric and fluorogenic signals. As PDA show low quantum yield, gold nanoparticles (GNPs) were used to amplify the fluorescence of the PDA by localized surface plasmon resonance. In this study, positively and negatively surface charged GNPs at different concentrations were complexed with negatively charged PDA liposome (GNP/PDA). Positively charged GNPs caused tight binding at the surface of negatively charged PDA liposome, became aggregated due to colloidal instability and thereby dramatically quenched the fluorescence of PDA. While negatively charged GNPs sparsely placed on the surface of the PDA liposome, at the optimized complexing condition, generated ∼10%of fluorescence amplification compared to non-complexed PDA liposome as observed by the photoluminescence spectra of the stable colloids. Under the optimum incubation conditions, GNP/PDA liposome that specifically binds with Pb²⁺via its phenolic group, exhibited increased fluorescence intensity compared to the non-complexed PDA liposome-at the same concentration of target Pb²⁺.