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Heterogeneous photocatalysts (PCs) have garnered attention for their sustainability and cost-effectiveness. 

A photoinduced reversible addition-fragmentation chain-transfer (photo-RAFT) polymerization technique in the presence of sodium pyruvate (SP) and pyruvic acid derivatives was developed. 

Infectious diseases caused by pathogens are a health burden, but traditional pathogen identification methods are complex and time-consuming. In this work, we have developed well-defined, multifunctional copolymers with rhodamine B dye synthesized by atom transfer radical polymerization (ATRP) using fully oxygen-tolerant photoredox/copper dual catalysis. ATRP enabled the efficient synthesis of copolymers with multiple fluorescent dyes from a biotin-functionalized initiator. Biotinylated dye copolymers were conjugated to antibody (Ab) or cell-wall binding domain (CBD), resulting in a highly fluorescent polymeric dye-binder complex. We showed that the unique combination of multifunctional polymeric dyes and strain-specific Ab or CBD exhibited both enhanced fluorescence and target selectivity for bioimaging of Staphylococcus aureus by flow cytometry and confocal microscopy. The ATRP-derived polymeric dyes have the potential as biosensors for the detection of target DNA, protein, or bacteria, as well as bioimaging. 

Photoinduced atom transfer radical polymerization (photo-ATRP) has risen to the forefront of modern polymer chemistry as a powerful tool giving access to well-defined materials with complex architecture. However, most photo-ATRP systems can only generate radicals under biocidal UV light and are oxygen-sensitive, hindering their practical use in the synthesis of polymer biohybrids. Herein, inspired by the photoinduced electron transfer-reversible addition–fragmentation chain transfer (PET-RAFT) polymerization, we demonstrate a dual photoredox/copper catalysis that allows open-air ATRP under green light irradiation. Eosin Y was used as an organic photoredox catalyst (PC) in combination with a copper complex (X–Cu II /L). The role of PC was to trigger and drive the polymerization, while X–Cu II /L acted as a deactivator, providing a well-controlled polymerization. The excited PC was oxidatively quenched by X–Cu II /L, generating Cu I /L activator and PC˙ + . The ATRP ligand (L) used in excess then reduced the PC˙ + , closing the photocatalytic cycle. The continuous reduction of X–Cu II /L back to Cu I /L by excited PC provided high oxygen tolerance. As a result, a well-controlled and rapid ATRP could proceed even in an open vessel despite continuous oxygen diffusion. This method allowed the synthesis of polymers with narrow molecular weight distributions and controlled molecular weights using Cu catalyst and PC at ppm levels in both aqueous and organic media. A detailed comparison of photo-ATRP with PET-RAFT polymerization revealed the superiority of dual photoredox/copper catalysis under biologically relevant conditions. The kinetic studies and fluorescence measurements indicated that in the absence of the X–Cu II /L complex, green light irradiation caused faster photobleaching of eosin Y, leading to inhibition of PET-RAFT polymerization. Importantly, PET-RAFT polymerizations showed significantly higher dispersity values (1.14 ≤ Đ ≤ 4.01) in contrast to photo-ATRP (1.15 ≤ Đ ≤ 1.22) under identical conditions.