近日，南开大学Dai-Wen Pang及其团队通过多层调控实现量子点纳米球的光致发光量子产率接近100%。该研究于2024年6月21日发表于国际一流学术期刊《美国化学会杂志》上。

据了解，与荧光染料或蛋白质相比，量子点(QDs)具有优越的亮度和光化学稳定性，使其成为高灵敏度单分子检测的首选。然而，它们的高表面能导致非特异性吸附和较差的胶体稳定性。在过去的几十年里，研究人员发现基于量子点的荧光纳米颗粒(FNs)不仅可以解决这些限制，而且可以提高检测灵敏度。然而，FNs的光致发光量子产率(PLQY)明显低于原量子点。迫切需要制定解决这一问题的策略，以进一步提高检测灵敏度。

在本研究中，研究人员发现自由基聚合制备的FNs的PLQY降低归因于两个因素:(1)自由基引起的QD配体解吸和QD壳层氧化导致的缺陷的产生，这些缺陷可以导致非辐射跃迁；(2)量子点与聚合物不相容导致的聚集引起的自吸收。

在此基础上，研究人员提出了一种多层调控策略，包括：(1)调控量子点配体；(2)精确控制自由基浓度；(3)构建聚合物交联结构，提高相容性，减少表面缺陷的形成。必须强调的是，多种因素的同时协调是必不可少的。因此，FNs的PLQY达到了世界纪录的97.6%，突破了目前65%的瓶颈。

这一调控概念的灵活应用为大规模生产高亮度量子点聚合物复合物铺平了道路，增强了它们在敏感生物医学检测中的潜在应用。

附：英文原文

Title: Multihierarchical Regulation To Achieve Quantum Dot Nanospheres with a Photoluminescence Quantum Yield Close to 100%

Author: Leping Lin, An-An Liu, Wei Zhao, Yin Yang, Dong-Liang Zhu, Bo-Ran Dong, Fei Ding, Di Ning, Xiaobo Zhu, Dingbin Liu, Dai-Wen Pang

Issue&Volume: June 21, 2024

Abstract: Quantum dots (QDs) exhibit superior brightness and photochemical stability, making them the preferred option for highly sensitive single-molecule detection compared with fluorescent dyes or proteins. Nevertheless, their high surface energy leads to nonspecific adsorption and poor colloidal stability. In the past decades, we have found that QD-based fluorescent nanoparticles (FNs) can not only address these limitations but also enhance detection sensitivity. However, the photoluminescence quantum yield (PLQY) of FNs is significantly lower compared with that of original QDs. It is urgent to develop a strategy to solve the issue, aiming to further enhance detection sensitivity. In this study, we found that the decrease of PLQY of FNs prepared by free radical polymerization was attributed to two factors: (1) generation of defects that can cause nonradiative transitions resulting from QD-ligands desorption and QD-shell oxidation induced by free radicals; (2) self-absorption resulting from aggregation caused by incompatibility of QDs with polymers. Based on these, we proposed a multihierarchical regulation strategy that includes: (1) regulating QD-ligands; (2) precisely controlling free radical concentration; and (3) constructing cross-linked structures of polymer to improve compatibility and to reduce the formation of surface defects. It is crucial to emphasize that the simultaneous coordination of multiple factors is essential. Consequently, a world-record PLQY of 97.6% for FNs was achieved, breaking through the current bottleneck at 65%. The flexible application of this regulatory concept paves the way for the large-scale production of high-brightness QD-polymer complexes, enhancing their potential applications in sensitive biomedical detection.

DOI: 10.1021/jacs.4c03308

Source: https://pubs.acs.org/doi/abs/10.1021/jacs.4c03308