NIR‐II Fluorescence Sensor Based on Steric Hindrance Regulated Molecular Packing for In Vivo Epilepsy Visualization

• Published in: Angewandte Chemie International Edition 2024-06, Vol.63 (26), p.e202403968-n/a
• Main Authors: Zhao, Mengyao, Lai, Weiping, Li, Benhao, Bai, Tianwen, Liu, Chunyan, Lin, Yanfei, An, Shixuan, Guo, Longhua, Li, Lei, Wang, Jianbo, Zhang, Fan
• Format: Article
• Language: English
• Subjects: activatable sensor; aggregation induced emission; Animals; Biological activity; Chemical compounds; Density Functional Theory; Emission; Emissions; Epilepsy; Epilepsy - diagnostic imaging; Fluorescence; Fluorescent Dyes - chemistry; Fluorophores; Hippocampus - diagnostic imaging; Infrared Rays; Mice; molecular packing; Molecular Structure; Near infrared radiation; Neuroimaging; Optical Imaging; Photon scatter; Quenching; Steric hindrance; steric hindrance quencher; the second near-infrared; Visualization
• ISSN: 1433-7851; 1521-3773; 1521-3773
• DOI: 10.1002/anie.202403968

Fluorescence sensing is crucial to studying biological processes and diagnosing diseases, especially in the second near‐infrared (NIR‐II) window with reduced background signals. However, it's still a great challenge to construct “off‐on” sensors when the sensing wavelength extends into the NIR‐II region to obtain higher imaging contrast, mainly due to the difficult synthesis of spectral overlapped quencher. Here, we present a new fluorescence quenching strategy, which utilizes steric hindrance quencher (SHQ) to tune the molecular packing state of fluorophores and suppress the emission signal. Density functional theory (DFT) calculations further reveal that large SHQs can competitively pack with fluorophores and prevent their self‐aggregation. Based on this quenching mechanism, a novel activatable “off‐on” sensing method is achieved via bio‐analyte responsive invalidation of SHQ, namely the Steric Hindrance Invalidation geNerated Emission (SHINE) strategy. As a proof of concept, the ClO−‐sensitive SHQ lead to the bright NIR‐II signal release in epileptic mouse hippocampus under the skull and high photon scattering brain tissue, providing the real‐time visualization of ClO− generation process in living epileptic mice. A new fluorescence sensing mechanism is presented by using steric hindrance quenchers to regulate the molecular packing state of fluorophores. The ClO− generation process in living epileptic mice brain is visualized by the SHINE sensor.