摘要
The aggregation-caused quenching(ACQ)rationale has been employed to improve the fluorescence imaging accuracy of nanocarriers by precluding free probe-derived interferences.However,its usefulness is undermined by limited penetration and low spatiotemporal resolution of NIR-Ⅰ(700-900 nm)bioimaging owing to absorption and diffraction by biological tissues and tissue-derived autofluorescence.This study aimed to develop ACQ-based NIR-Ⅱ(1000-1700 nm)probes to further improve the imaging resolution and accuracy.The strategy employed is to install highly planar and electron-rich julolidine into the 3,5-position of aza-BODIPY based on the larger substituent effects.The newly developed probes displayed remarkable photophysical properties,with intense absorption centered at approximately 850 nm and bright emission in the 950-1300 nm region.Compared with the NIR-Ⅰ counterpart P2,the NIR-Ⅱ probes demonstrated superior water sensitivity and quenching stability.ACQ1 and ACQ6 exhibited more promising ACQ effects with absolute fluorescence quenching at water fractions above 40% and higher quenching stability with less than 2.0% fluorescence reillumination in plasma after 24 h of incubation.Theoretical calculations verified that molecular planarity is more important than hydrophobicity for ACQ properties.Additionally,in vivo and ex vivo reillumination studies revealed less than 2.5% signal interference from prequenched ACQ1,in contrast to 15% for P2.
基金
supported by the National Natural Science Foundation of China(Nos.82273867 and 82030107)
the Science and Technology Commission of Shanghai Municipality(No.21430760800,China).
