Metal Nanoparticle Enhanced Molecular Triplet Generation for Singlet Oxygen Production and Antibacterial Application.

Li, Zhanzhao; Xu, Ziwei; Gong, Shaokuan; Liu, Kaizhen; Yang, Jin; Han, Xue; Xu, Niu; Song, Weiming et al. · Nano Lett · 2025

basic_science · Level V

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Abstract

Developing sensitizers for highly efficient molecular spin-triplet excited state generation is vital for many applications. Herein, we show Au and Pt nanoparticles as sensitizers for triplet generation in adjacent 9-anthracene carboxylic acid (ACA) molecules. Ultrafast spectroscopy reveals hole transfer from ACA to Au and Pt, with different time constants depending on the electronic structure of metal, followed by spin-flip in metal and charge recombination to produce triplet state (<sup>3</sup>ACA*). <sup>3</sup>ACA* can transfer its energy to molecular oxygen to produce singlet oxygen (<sup>1</sup>O<sub>2</sub>), with quantum yields of 67.8% and 42.3% for Au-ACA and Pt-ACA, ∼3 and 2 times higher than that of free ACA, respectively. The nanoparticle-ACA nanohybrids show high antibacterial activity, attributed to the synergistic effect of nanoparticle enhanced <sup>1</sup>O<sub>2</sub> generation and photothermal effect from plasmonic hot carriers. This bifunctionality of metal nanoparticle-molecule nanohybrids is promising for many applications including photodynamic therapy and photocatalysis.