Conjugated polymer nanoparticles with Ag+-sensitive fluorescence emission: A new insight into the cooperative recognition mechanism

Abstract

Hybrid fluorescent nanoparticles (NPs) were developed on the basis of a series of chemically close polyfluorene-based conjugated polymers and an amphiphilic polymer. NPs constructed from polyfluorene with 2,1,3- benzothiadiazole units incorporated in the backbone of polymer chains displayed Ag+-sensitive fluorescence emission features with high selectivity, which was demonstrated to be attributable to Ag+-induced aggregation and fluorescence quenching. The negatively charged sulfonic acid groups of amphiphilic polymer components located on the surfaces of the hybrid NPs and therefore provided binding sites for metal ions, which was found indispensable for the observed silver ion sensing features of the as-prepared hybrid NPs. Additionally, it was demonstrated that the benzothiadiazole-containing conjugated polymer components not only acted as the fluorescence signaling source but also participated in the metal binding/recognition processes. Thus, a mechanism of cooperative recognition-based aggregation-induced fluorescence static quenching and Ag+-triggered fluorescence dynamic quenching responsible for the observed Ag+ sensing results was confirmed. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.