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.

Recent Developments in Semiconducting Polymer Dots for Analytical Detection and NIR-II Fluorescence Imaging

“…Similarly, the incorporation of sulfonated-polystyrene amphiphilic polymers into the PFBT Pdot matrix could be used to detect Ag + ions, originated from the interactions of the negatively charged sulfonic groups of polystyrene with the thiadiazole groups on PFBT. 95 A more than 74% decrease in emission intensity of PFBT/PS-SO 3 H Pdots was seen upon the addition of Ag + . On the contrary, no fluorescence change was observed for bare PFBT Pdots without the incorporation of PS-SO 3 H.…”

“…The developed Pdot-based sensor could sensitively measure the ion concentrations of (10.17 ± 1.34) × 10 –6 and (16.16 ± 1.82) × 10 –6 M for Cu 2+ and Fe 2+ , respectively in Dulbecco’s Modified Eagle Medium. Similarly, the incorporation of sulfonated-polystyrene amphiphilic polymers into the PFBT Pdot matrix could be used to detect Ag + ions, originated from the interactions of the negatively charged sulfonic groups of polystyrene with the thiadiazole groups on PFBT . A more than 74% decrease in emission intensity of PFBT/PS-SO 3 H Pdots was seen upon the addition of Ag + .…”

Recent Advances of Activatable Molecular Probes Based on Semiconducting Polymer Nanoparticles in Sensing and Imaging

“…Thus, there is an urgent need to detect silver ions (Ag + ) with high selectivity in aqueous milieu and biological systems. An activatable probe for Ag + sensing was developed by encapsulating P4 with sulfonated polystyrene‐ block ‐poly(ethylene‐ ran ‐butylene)‐ block ‐polystyrene (PS‐SO 3 H) . Benzothiadiazole of P4 not only provided the read‐out signals, but also played the role of specific chelating with Ag + .…”

Nanoparticles made of π-conjugated compounds targeted for chemical and biological applications

“…Up to now, metal ion sensing by OSNs of Cu 2+ , Ag + , Hg 2+ , Cr(VI), Fe 2+ , Fe 3+ and Pb 2+ have been reported. [67][68][69][70][71][72][73][74][75][76][77][78][79][80] Table 1 summarizes the p-conjugated compounds to prepare NPs for detecting specific metal ions. Two major mechanisms are involved in these metal ion-sensing systems.…”