Antoine, Rodolphe

Coll, Jean-luc

Comby-Zerbino, Clothilde

Garcia, Daniel Jaque

Le Guével, Xavier

Marin, Riccardo

Mohammad, Walaa

Ogayar, Marina Paris

Resch-Genger, Ute

Trouillet, Vanessa

Wegner, K. David

English

Gold-based nanoparticles below 2 nm in size are promising as luminescent probes for in vivo bioimaging, owing to their brightness and rapid renal clearance. However, their use as contrast agents in the near-infrared II (NIR-II, 1000–1700 nm) range remains challenging due to their low photoluminescence (PL) quantum yield. To address this, PL enhancement can be achieved by either rigidifying the ligand-shell structure or increasing the size of the ligand shell. In this study, we synthesized ultra-small gold nanoparticles stabilized by co-ligands, namely monothiol and short dithiol molecules. By precisely controlling the amount of reducing agent used during particle preparation, we successfully modulated the physicochemical properties of the co-ligand shell, including its size, composition, and structure. Consequently, we achieved a remarkable 60-fold increase in the absorption cross-section at 990 nm while maintaining the small size of the 1.5-nm metal core. The analytical and optical characterization of our thiol-capped gold nanoparticles indicates that the ligand shell size is governed by the quantity of the reducing agent, which, in turn, impacts the balance between radiative and non-radiative processes, thereby influencing the PL quantum yield

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Enhanced brightness of ultra-small gold nanoparticles in the second biological window through thiol ligand shell control

https://publikationen.bibliothek.kit.edu/1000164255/151685607

Enhanced brightness of ultra-small gold nanoparticles in the second biological window through thiol ligand shell control

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