SwissKnife-Inspired Multifunctional Fluorescence Probes for Cellular Organelle Targeting Based on Simple AIEgens

Abstract

Facile, efficient, and mass production of aggregation-induced emission (AIE) luminogens (AIEgens) with excited-state intramolecular proton transfer (ESIPT) characteristics was achieved by a one-step condensation reaction of 2-(hydrazonomethyl)phenol with benzaldehydes. The function of as-prepared AIEgens could be tuned easily by varying the functional group being carried on the phenyl ring of benzaldehyde just like a Swiss knife handle. The suitable distance and angle of the intramolecular hydrogen bond in these AIEgens endowed them with ESIPT properties, intense solid-state luminescence, and large Stokes shifts (155−169 nm). These AIEgens could not only serve as biological probes showing specific targeting to lipid droplets, endoplasmic reticulum, and lysosomes, respectively, but also generate reactive oxygen species upon visible light irradiation to make them promise for photodynamic therapy.

Dual-Functional NIR AIEgens for High-Fidelity Imaging of Lysosomes in Cells and Photodynamic Therapy

“…Owing to its high light stability, long-term in situ imaging, low toxicity, excellent brightness, and excellent stability, AIE has attracted more and more scientists’ attention . Nowadays, the luminogens with AIE characteristics have been widely employed in the areas of the biosensing and bioimaging. − …”

An ESIPT‐Dependent AIE Fluorophore Based on HBT Derivative: Substituent Positional Impact on Aggregated Luminescence and its Application for Hydrogen Peroxide Detection

“…Although many fluorescent sensors based on various fluorophores including fluorescein, rhodamines, pyrenes, and others have been used to detect H 2 O 2 [30,31] . However, lots of them went through small Stokes shifts and thus encounter some interference influence in fluorescence analysis, including self‐absorption or the effect of internal filtration [32,33] . Taking the advantages of AIE and ESIPT characteristics, Probe‐1 (Figure 4a) was designed and applied to the fluorescence imaging of cellular H 2 O 2 .…”

“…[30,31] However, lots of them went through small Stokes shifts and thus encounter some interference influence in fluorescence analysis, including self-absorption or the effect of internal filtration. [32,33] Taking the advantages of AIE and ESIPT characteristics, Probe-1 (Figure 4a) was designed and applied to the fluorescence imaging of cellular H 2 O 2 . Since the hydroxyl group in the p-BHBT was protected by benzyl boronic pinacol ester group (a H 2 O 2 selective trigger), the excited-state proton transfer from the hydroxyl group (proton donor) to nitrogen (proton acceptor) will be blocked, which results in fluorescence quenching of Probe-1.…”

Aggregation‐Induced Emission Nanoprobes Working in the NIR‐II Region: From Material Design to Fluorescence Imaging and Phototherapy

“…Compared to conventional exogenous contrast agents, such as organic dyes, [ 100,101 ] quantum dots, [ 102 ] upconversion nanoparticles, [ 103,104 ] and metallic nanoparticles, [ 105 ] AIE nanoprobes are better candidates in fluorescence imaging due to their low cytotoxicity, strong photostability, and good biocompatibility. To date, AIE nanoprobes have been successfully applied in organelle targeting, [ 106,107 ] intracellular environment responses, [ 108,109 ] and cell process tracing. [ 110 ] Recent efforts in AIE nanoprobes have further extended the optical working region into the NIR‐II window and contributed to biomedical applications, including in vivo tumor targeting, vascular imaging and organ imaging.…”