Kataoka Keita, Nakabayashi Kazuhiro, Lo Chen-Tsyr, Mori Hideharu
Graduate School of Organic Materials Science, Yamagata University, 4-3-16 Jonan, Yonezawa 992-8510, Japan.
Department of Materials and Optoelectronic Science, National Sun Yat-Sen University, 70 Lienhai Road, Kaohsiung 80424, Taiwan.
Polymers (Basel). 2022 Mar 27;14(7):1362. doi: 10.3390/polym14071362.
Stimuli-responsive polymeric nanoparticles (NPs) exhibit reversible changes in the dispersion or aggregation state in response to external stimuli. In this context, we designed and synthesized core-shell NPs with threonine-containing weak polyelectrolyte shells and fluorescent cross-linked cores, which are applicable for the detection of pH changes and amine compounds in aqueous solution. Stable and uniform NP(dTh) and NP(Fl), consisting of fluorescent symmetric diphenyl dithiophene (dTh) and diphenyl fluorene (Fl) cross-linked cores, were prepared by site-selective Suzuki coupling reactions in self-assembled block copolymer. NP(Fl) with the Fl unit in the core showed a high fluorescence intensity in different solvents, which is regarded as an aggregation-induced emission-type NP showing strong emission in aggregated states in the cross-linked core. Unimodal NPs were observed in water at different pH values, and the diameter of NP(Fl) changed from 122 (pH = 2) to 220 nm (pH = 11). Furthermore, pH-dependent changes of the fluorescence peak positions and intensities were detected, which may be due to the core aggregation derived from the deprotonation of the threonine-based shell fragment. Specific interactions between the threonine-based shell of NP(Fl) and amine compounds (triethylamine and -phenylenediamine) resulted in fluorescence quenching, suggesting the feasibility of fluorescent amine detection.
刺激响应性聚合物纳米颗粒（NPs）在外部刺激下会表现出分散或聚集状态的可逆变化。在此背景下，我们设计并合成了具有含苏氨酸的弱聚电解质壳层和荧光交联核的核壳型纳米颗粒，其适用于检测水溶液中的pH变化和胺类化合物。通过在自组装嵌段共聚物中进行位点选择性铃木偶联反应，制备了由荧光对称二苯基二噻吩（dTh）和二苯基芴（Fl）交联核组成的稳定且均匀的NP（dTh）和NP（Fl）。核心带有Fl单元的NP（Fl）在不同溶剂中显示出高荧光强度，被视为一种聚集诱导发光型纳米颗粒，在交联核的聚集状态下表现出强烈发射。在不同pH值的水中观察到单峰纳米颗粒，NP（Fl）的直径从122nm（pH = 2）变为220nm（pH = 11）。此外，检测到荧光峰位置和强度的pH依赖性变化，这可能是由于基于苏氨酸的壳层片段去质子化导致的核心聚集。NP（Fl）基于苏氨酸的壳层与胺类化合物（三乙胺和对苯二胺）之间的特异性相互作用导致荧光猝灭，表明荧光胺检测具有可行性。
