Laboratory of Functionalized Molecular Solids, Ministry of Education, Anhui Key Laboratory of Chemo/Biosensing, Laboratory of Biosensing and Bioimaging (LOBAB), College of Chemistry and Materials Science, Anhui Normal University, Wuhu 241002, P. R. China.
J Mater Chem B. 2021 Apr 28;9(16):3554-3562. doi: 10.1039/d1tb00433f.
In this study, a novel reaction-based A-A-A (acceptor-acceptor-acceptor) type two-photon fluorescent probe, BTC, is prepared using the benzothiadiazole (BTD) scaffold as the two-photon fluorophore and electron-accepting centre. Two β-chlorovinyl aldehyde moieties are symmetrically connected to both ends of the BTD scaffold and act as reaction groups to recognize SO2 and quenching groups to make the dis-activated probe stay at off-state due to their weak electron-withdrawing effect. In the presence of SO2 derivatives, the aldehyde groups are consumed through aldehyde addition, resulting in the activation of intramolecular charge transfer (ICT) processes and therefore recovering the fluorescence of the probe. The designed probe shows excellent two-photon properties including large two-photon absorption cross-sections (TPA) of 91 GM and photostability. Beyond these, the BTC probe exhibits a fast response to SO2 within 30 s, high specificity without foreign interference and a broad detection range from 500 nM to 120 μM with a detection limit of 190 nM. The designed fluorescent probe is further applied to the two-photon imaging of exogenous and endogenous SO2 derivatives under different physiological processes in HeLa cells and zebrafish with satisfactory results. We believe that the proposed design strategy can be extended to fabricate versatile BTD-based two-photon fluorescent probes through molecular engineering for further applications in bioassays and two-photon imaging.
在这项研究中，我们制备了一种新型的基于反应的 A-A-A（受体-受体-受体）型双光子荧光探针 BTC，该探针以苯并噻二唑（BTD）为双光子荧光团和电子受体中心。两个β-氯代乙烯醛部分对称地连接到 BTD 支架的两端，作为反应基团来识别 SO2，并作为猝灭基团，由于其较弱的吸电子效应，使非激活探针保持关闭状态。在 SO2 衍生物存在的情况下，通过醛加成消耗醛基，从而激活分子内电荷转移（ICT）过程，因此恢复探针的荧光。该设计的探针表现出优异的双光子性质，包括大的双光子吸收截面（TPA）为 91 GM 和光稳定性。除此之外，BTC 探针对 SO2 的响应速度很快，在 30 秒内即可完成，特异性高，不受外来干扰，检测范围从 500 nM 到 120 μM，检测限为 190 nM。设计的荧光探针进一步应用于 HeLa 细胞和斑马鱼不同生理过程中外源和内源性 SO2 衍生物的双光子成像，结果令人满意。我们相信，所提出的设计策略可以通过分子工程扩展到制造各种基于 BTD 的双光子荧光探针，以进一步应用于生物测定和双光子成像。
