Hong Kyeong-Im, Kim Younghun, Lee Jeong Heon, Chu Kang Ho, Jang Woo-Dong
Department of Chemistry, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 03722, Korea.
Chem Biomed Imaging. 2023 Jul 10;1(4):395-402. doi: 10.1021/cbmi.3c00055. eCollection 2023 Jul 24.
Mitochondrial imaging is crucial for studying disease pathogenesis and diagnosis. However, commercially available mitochondria-specific fluorescent probes are limited due to the difficulty in modifying cationic probes for functional bioimaging of mitochondria. To address this, we prepared a hydroxythiophene-conjugated benzothiazole (BzT-OH) as a platform for the design of functional fluorescent probes. Two probes, BzT-OAc and BzT-OAcryl, were synthesized by substituting the hydroxy group in BzT-OH with acetate and acrylate groups, respectively. BzT-OAc demonstrated blue fluorescence that shifted to green emission after enzymatic cleavage of the acetate group, allowing for monitoring of endogenous esterase activity. BzT-OAcryl showed high selectivity for cysteine at pH > 8.0, owing to its pH-responsive property, and could detect pH perturbations caused by mitochondrial dysfunction. Both probes exhibited high biocompatibility, quantum yield, and large Stokes shifts in mitochondria. BzT-OH can be easily conjugated with other functional groups and substrates of various enzymes for designing fluorescent probes for functional mitochondrial imaging. The photofunctional property of the probe can be changed due to the involvement of the hydroxyl group in the excited state intermolecular proton transfer.
线粒体成像对于研究疾病发病机制和诊断至关重要。然而，由于难以对阳离子探针进行修饰以用于线粒体的功能性生物成像，市售的线粒体特异性荧光探针有限。为了解决这个问题，我们制备了一种羟基噻吩共轭苯并噻唑（BzT-OH）作为设计功能性荧光探针的平台。通过分别用乙酸酯和丙烯酸酯基团取代BzT-OH中的羟基，合成了两种探针BzT-OAc和BzT-OAcryl。BzT-OAc表现出蓝色荧光，在乙酸酯基团被酶切后转变为绿色发射，从而能够监测内源性酯酶活性。由于其pH响应特性，BzT-OAcryl在pH>8.0时对半胱氨酸具有高选择性，并且可以检测由线粒体功能障碍引起的pH扰动。两种探针在线粒体中均表现出高生物相容性、量子产率和大斯托克斯位移。BzT-OH可以很容易地与其他官能团和各种酶的底物共轭，用于设计功能性线粒体成像的荧光探针。由于羟基参与激发态分子间质子转移，探针的光功能性质可能会发生变化。
