Hajda Agata, Guha Rweetuparna, Copp Stacy Marla, Olesiak-Bańska Joanna
Institute of Advanced Materials, Wroclaw University of Science and Technology Wrocław Poland
Department of Materials Science and Engineering, University of California Irvine CA 92697 USA.
Chem Sci. 2024 Dec 16;16(4):1737-1745. doi: 10.1039/d4sc05853d. eCollection 2025 Jan 22.
Near-infrared (NIR) emitters with high two-photon absorption (2PA) cross-sections are of interest to enable imaging in the tissue transparency windows. This study explores the potential of DNA-stabilized silver nanoclusters (Ag -DNAs) as water-soluble two-photon absorbers. We investigate 2PA of four different atomically precise Ag -DNA species with far-red to NIR emission and varying nanocluster and ligand compositions. 2PA cross-sections, , were determined by two-photon excited luminescence (2PEL) technique for a wide wavelength range from 810 to 1400 nm. The Ag -DNAs exhibited reversed strength of corresponding transitions in the two-photon regime, as compared to one-photon, which further demonstrates the complex photophysics of these emitters. Maximal 2PA cross-section value (∼582 GM) was observed for (DNA)[Ag], which is stabilized by 3 DNA oligomers. (DNA)[AgCl] presented distinct 2PA behavior from the Ag -DNAs without chlorido ligands, with a high 2PA of 176 GM at 1050 nm. Our findings support the potential of Ag -DNAs as NIR-to-NIR two-photon probes that are both excited and emit in the NIR. Their high and fluorescence quantum yield values result in superior two-photon brightness on the order of ∼10 GM, significantly higher than water-soluble organic fluorophores.
具有高双光子吸收（2PA）截面的近红外（NIR）发射体对于实现组织透明窗口成像很有意义。本研究探索了DNA稳定的银纳米团簇（Ag-DNAs）作为水溶性双光子吸收剂的潜力。我们研究了四种不同的原子精确的Ag-DNA物种的双光子吸收，它们具有从远红到近红外的发射以及不同的纳米团簇和配体组成。通过双光子激发发光（2PEL）技术在810至1400nm的宽波长范围内测定了双光子吸收截面（）。与单光子情况相比，Ag-DNAs在双光子 regime 中表现出相应跃迁强度的反转，这进一步证明了这些发射体复杂的光物理性质。对于由3个DNA寡聚物稳定的（DNA）[Ag]，观察到最大双光子吸收截面值（约582 GM）。（DNA）[AgCl]呈现出与没有氯配体的Ag-DNAs不同的双光子吸收行为，在1050nm处具有176 GM的高双光子吸收。我们的研究结果支持了Ag-DNAs作为近红外到近红外双光子探针的潜力，它们在近红外区域被激发并发射。它们高的 和荧光量子产率值导致约10 GM量级的优异双光子亮度，明显高于水溶性有机荧光团。
