Biswakarma Dipen, Dey Nilanjan, Bhattacharya Santanu
Department of Organic Chemistry, Indian Institute of Science Bangalore Karnataka 560012 India.
Jawaharlal Nehru Centre for Advanced Scientific Research Jakkur Bengaluru 560064 Karnataka India.
Chem Sci. 2022 Feb 3;13(8):2286-2295. doi: 10.1039/d1sc05424d. eCollection 2022 Feb 23.
The self-assembly properties of new biocompatible, thermoreversible fluorescent hydrogels, composed of amino acid residues, , l-phenylalanine (PyL-PheOx) and l-tyrosine (PyL-TyrOx), have been reported. Spectroscopic investigations indicate that PyL-PheOx forms π-stacked 'compact' aggregates, while 'loose' aggregates with stronger CT characteristics are observed for PyL-TyrOx. Both the compounds showed the presence of fibrous networks in the self-assembled state. Circular dichroism spectral studies indicate the formation of -helical and -helical structures for PyL-PheOx and PyL-TyrOx, respectively. A striking gel-to-sol transition, caused by oxidative decomposition, is explicitly noticed in the presence of hypochlorite. A mechanistic investigation reveals the oxidation of the acyl aroyl hydrazine core of the gelators in the presence of ClO. In addition to this, change in the fluorescence emission intensity of the hydrogel in the presence of ClO is utilized for the analysis of commercial bleach samples. Gel-coated paper strips are also developed for the on-site detection of ClO. Furthermore, the system is utilized for imaging hypochlorite in live mammalian cells.
据报道，由氨基酸残基、L-苯丙氨酸（PyL-PheOx）和L-酪氨酸（PyL-TyrOx）组成的新型生物相容性、热可逆荧光水凝胶具有自组装特性。光谱研究表明，PyL-PheOx形成π堆积的“紧密”聚集体，而PyL-TyrOx则观察到具有更强电荷转移（CT）特性的“松散”聚集体。两种化合物在自组装状态下均显示出纤维网络的存在。圆二色光谱研究表明，PyL-PheOx和PyL-TyrOx分别形成α-螺旋和β-螺旋结构。在次氯酸盐存在下，明显观察到由氧化分解引起的显著的凝胶-溶胶转变。机理研究表明，在ClO存在下，凝胶剂的酰基芳酰肼核心发生氧化。除此之外，利用次氯酸盐存在下水凝胶荧光发射强度的变化来分析商业漂白剂样品。还开发了凝胶涂层纸条用于现场检测ClO。此外，该系统用于对活的哺乳动物细胞中的次氯酸盐进行成像。
