Far-red/near-infrared fluorescence light-up probes for specific in vitro and in vivo imaging of a tumour-related protein

Abstract

As lysosomal protein transmembrane 4 beta (LAPTM4B) is an important biomarker for many solid tumours, development of small-molecule fluorescence light-up probes for detection and imaging of LAPTM4B proteins is particularly valuable. In this work, we reported the design and synthesis of a far-red/near-infrared (FR/NIR) fluorescence light-up probe DBT-2EEGIHGHHIISVG, which could specifically visualize LAPTM4B proteins in cancer cells and tumour-bearing live mice. DBT-2EEGIHGHHIISVG was synthesized by the conjugation of two LAPTM4B-binding peptide ligands (EEGIHGHHIISVG) with one environment-sensitive fluorogen, 4,7-di(thiophen-2-yl)-2,1,3-benzothiadiazole (DBT). Owing to the intramolecular charge transfer character of DBT, DBT-2EEGIHGHHIISVG is weakly emissive in aqueous solution, but switches to fluoresce upon LAPTM4B proteins specifically bind to the peptide ligand of the probe, which provide the DBT with hydrophobic microenvironment, greatly reducing its charge transfer effect with water. It is found that DBT-2EEGIHGHHIISVG can achieve targeted imaging of LAPTM4B proteins in HepG2 cancer cells and visualize LAPTM4B protein-expressed tumour tissues of live mice in a selective and high-contrast manner.

From Live Cells to Caenorhabditis elegans: Selective Staining and Quantification of Lipid Structures Using a Fluorescent Hybrid Benzothiadiazole Derivative

“…For instance, tumor cells under hypoxic condition were labeled, 21 ligand trafficking in artificial and living cell systems could be probed, 22 and other applications are found. 23 − 27 Among these new applications, selective LDs staining was described by us 28 and by others. 29 We have shown the potential of BTD fluorophores for selective mitochondrial staining, 30 for dynamic and endocytic internalization studies, 28 and others, 31 , 32 as we have recently highlighted.…”

When the strategies for cellular selectivity fail. Challenges and surprises in the design and application of fluorescent benzothiadiazole derivatives for mitochondrial staining

“…After our pioneering works using -extended BTDs as cellular markers, 54 several groups published fluorescent BTD derivatives for different organelles and cells' components selective staining with success. [88][89][90][91][92][93][94][95][96][97][98][99] Despite the many strides in the development of new and selective BTD markers, there still remains much work to be done. For instance, it is necessary to study the commonly used strategies to direct fluorophores inside living cells to a specific organelle using fluorescent BTDs.…”

Nondestructive Analysis of Tumor-Associated Membrane Protein Integrating Imaging and Amplified Detection in situ Based on Dual-Labeled DNAzyme

“…Currently, there are two main ways for the profiling of TMPs: ex situ detection and in situ imaging 6 - 8 . Among the ex situ detection methods, the most widely used method is western blotting.…”

“…Immunofluorescence is one of the most representative and commonly-used imaging method, but is still far from satisfactory at present. Great attentions are being paid on the development of novel high-/super-resolution microscopy and fluorescent molecular probes 8 , 12 - 13 . Despite the great progress, the gap of in situ imaging for quantitative analysis should still be filled by ex situ detection.…”