Aggregation/Self-Assembly-Induced Approach for Efficient AuAg Bimetallic Nanocluster-Based Photosensitizers

Abstract

Great efforts have been devoted to the exploration of potential diagnostic and therapeutic applications of thiolate-protected gold nanoclusters (Au NCs). One of the therapeutic applications is the photosensitized generation of highly reactive singlet oxygen (1O2) using Au NCs for photodynamic therapy. However, there is scope for improving the 1O2-generation efficiency of Au NC photosensitizers. In this study, we exploit three strategies to improve the 1O2-generation efficiency of glutathione-protected Au NCs: (i) doping with silver (i.e., using bimetallic AuAg NCs, (ii) achieving aggregation-induced emission (AIE) using a Au­(I)–thiolate complex, and (iii) achieving self-assembly-induced emission (SAIE) using a polymer nanogel. The combination of these three effects dramatically increased the 1O2-generation efficiency and enhanced the luminescence of the glutathione-protected Au NCs, owing to the inhibition of the nonradiative decay pathways. Finally, the photosensitizers based on AuAg NC@nanogel composites were successfully used for antimicrobial photodynamic therapy (a-PDT) against oral bacteria. This study provides general insights into the molecular design of water-soluble Au NC photosensitizers for therapeutic applications.

Insights and Perspectives Regarding Nanostructured Fluorescent Materials toward Tackling COVID-19 and Future Pandemics

“… 100 , 101 The as-synthesized BSA-templated AuAgNCs alloys showed a strongly enhanced SOG rate (∼45 times higher than that of the monometallic BSA-Ag 13 NC), which is inversely correlated to their photoluminescence intensities. In another study, Hikosou et al 234 synthesized the glutathione-protected bimetallic AuAg nanoclusters and a AuAg NCs@chitosan nanogel. The results show that the AuAgNCs had a 27% higher SOG ability as compared to AuNCs, while the AuAgNCs@chitosan nanogel (50 μg/mL) could kill more than 90% of Streptococcus mutans within 1 min under light-emitting diode (LED) irradiation.…”

Supramolecules‐Guided Synthesis of Brightly Near‐Infrared Au22 Nanoclusters with Aggregation‐Induced Emission for Bioimaging

“…See also Figure S7a,b, Supporting Information). This phenomenon implies that the enhanced PL intensity is due to a rigidification mechanism . We note that BSA‐AuNCs precipitate out immediately upon the fast addition of PAH at pH 5.…”

Rejuvenated Photodynamic Therapy for Bacterial Infections

“…Classical PSs are poorly soluble and easily aggregate under physiological conditions, which seriously restrict their clinical efficacy for PDAT . In this regard, several nanostructured self‐assemblies have been developed based on classical PSs with significant improvements in their PDAT applications . For example, Huang and co‐workers developed phthalocyanine‐assembled nanodots, which demonstrated excellent PDAT activity against normal and drug‐resistant bacterial strains via the type I mechanism .…”