An Ultrasensitivity Fluorescent Probe Based on the ICT-FRET Dual Mechanisms for Imaging β-Galactosidase in Vitro and ex Vivo
作者:Xiuqi Kong、Min Li、Baoli Dong、Yaguang Yin、Wenhui Song、Weiying Lin
DOI:10.1021/acs.analchem.9b03639
日期:2019.12.17
Emergence of fluorescence imaging with real-time and in situ manners has revolutionized the fields of tracing and defining enzymes in biological systems. β-galactosidase is a kind of enzyme that plays vital roles in controlling multitudes of cellular functions and participating in disease pathogenesis. Thus, building fluorescent probes with high sensitivity and fidelity for visualizing β-galactosidase in biological systems is very significative. Herein, we engineered the first ultrsensitivity ratiometric fluorescent probe CG based on ICT-FRET synergetic mechanisms for detecting β-galactosidase. The spectrum data show that probe CG has a fast response (<20 s), as well as a very low detection limit to β-galactosidase (0.081 U/mL). Moreover, by calculation of a serious of kinetic parameters including Km (1.42 μM), kcat (7.04 s–1), and kcat/Km (4.96 μM–1 s–1), CG demonstrates high affinity and high catalytic efficiency to β-galactosidase. Because of its excellent water solubility, CG has well biocompatibility to visualize the β-galactosidase in living cells. Furthermore, for imaging in bioapplications, CG is capable of detecting β-galactosidase not only in overexpressed cell lines but also in transient expressed cell lines. Significantly, CG can monitor β-galactosidase ex vivo selectively. We hope ongoing work to employ CG can be as an ultrasensitive powerful tool for further seeking the physiological and pathological functions in biological organisms.
实时和原位荧光成像技术的出现彻底改变了生物系统中酶的追踪和定义领域。β-半乳糖苷酶是一种在控制多种细胞功能和参与疾病发病机制中发挥重要作用的酶。因此,构建高灵敏度和高保真的荧光探针来观察生物系统中的β-半乳糖苷酶意义重大。在此,我们基于 ICT-FRET 协同机制设计了首个用于检测 β-半乳糖苷酶的超灵敏度比率荧光探针 CG。光谱数据显示,探针 CG 响应速度快(<20 s),对 β-半乳糖苷酶的检测限非常低(0.081 U/mL)。此外,通过计算 Km (1.42 μM)、kcat (7.04 s-1) 和 kcat/Km (4.96 μM-1 s-1) 等动力学参数,CG 对 β-半乳糖苷酶具有高亲和力和高催化效率。由于 CG 具有极佳的水溶性,因此具有良好的生物相容性,可用于观察活细胞中的β-半乳糖苷酶。此外,在生物应用成像方面,CG 不仅能检测过表达细胞系中的β-半乳糖苷酶,还能检测瞬时表达细胞系中的β-半乳糖苷酶。值得注意的是,CG 能选择性地监测体内外的β-半乳糖苷酶。我们希望目前正在进行的工作能将 CG 作为一种超灵敏的有力工具,用于进一步探究生物体内的生理和病理功能。