一种基于多烯桥接的近红外荧光生物成像探针设计及机制研究

Design and Mechanism Study of a Near-Infrared Fluorescent Bioimaging Probe Based on Polyene Bridging

摘要: 本文通过量子化学计算(Gaussian-16等软件)研究基于多烯桥接的杂化罗丹明近红外荧光生物成像探针(Rh-1、Rh-2、Rh-3)的成像机制。多烯碳链作为桥接单元，通过π电子离域连接罗丹明与苯并吲哚嗡，形成扩展共轭体系。研究显示，多烯碳链长度决定荧光性能：链越长，电子吸收和辐射波长越长。当碳链含5个C-C键时(Rh-3)，荧光波长达到近红外NIR-II区的1093 nm，吸收波长延伸至1029 nm。激发过程分析表明，探针电子跃迁以局域激发为主，基态与激发态结构稳定性高，可减少荧光淬灭。该研究揭示“链长–共轭–波长”构效关系，为NIR-II区探针设计提供理论依据，未来可通过杂原子修饰、引入响应性基团优化荧光探针的性能。

Abstract: This paper designs hybrid rhodamine-based near-infrared fluorescent bioimaging probes (Rh-1, Rh-2, Rh-3) based on polyene bridging and investigates their imaging mechanisms via quantum chemical calculations (using software such as Gaussian-16). The polyene carbon chain, as a bridging unit, connects rhodamine and benzindolium through π-electron delocalization, forming an extended conjugated system. Studies show that the length of the polyene carbon chain determines fluorescent performance: a longer chain leads to longer electron absorption and emission wavelengths. When the carbon chain contains 5 C-C bonds (Rh-3), the fluorescence wavelength reaches 1093 nm in the NIR-II region, with the absorption wavelength extending to 1029 nm. Excitation process analysis reveals that the electron transition of the probes is dominated by local excitation, and the structures of the ground and excited states are highly stable, which can reduce fluorescence quenching. This study clarifies the “chain length-conjugation-wavelength” structure-activity relationship, providing a theoretical basis for the design of NIR-II region probes. Future optimization can be achieved by heteroatom modification and introduction of responsive groups.