A lysosome-targeted fluorescent probe based on a BODIPY structure for Cys/Hcy detection

Understanding the roles of biothiols like cysteine (Cys) and homocysteine (Hcy) is crucial in physiological and pathological studies. Prior research has established that these molecules are involved in various cellular processes. However, detecting them selectively in complex biological environments remains challenging. Existing methods often lack the specificity or sensitivity needed for accurate detection. This limitation has driven the need for new optical probes that can target specific organelles. Lysosomes, being acidic and membrane-bound, require probes with specific targeting groups. While fluorescent probes have been developed for general biothiol detection, few combine lysosomal targeting with high selectivity. The gap in targeted and sensitive detection motivates the development of novel probes. This paper addresses the need for a lysosome-specific probe with enhanced Cys/Hcy detection capabilities. The study contributes by introducing a probe that integrates both targeting and sensing functionalities.

The aim of this research is to develop a fluorescent probe that can selectively detect Cys and Hcy while targeting lysosomes in living cells. The specific problem addressed is the lack of probes that combine lysosomal targeting with high sensitivity and selectivity for these biothiols. The motivation stems from the importance of Cys and Hcy in various physiological processes. Detecting these molecules in lysosomes could provide insights into their roles in cellular function. The study seeks to overcome the limitations of existing probes by incorporating a lysosomal targeting group. The design incorporates a BODIPY-based structure for fluorescence. The probe's ability to emit fluorescence upon binding to Cys/Hcy is a key feature. The ultimate goal is to enable real-time detection of these biothiols in living cells.

The researchers designed a fluorescent probe called NBD-B-T based on a BODIPY structure. The probe was synthesized by incorporating a sensing group and a lysosomal targeting group. The sensing group used was 7-nitro-2,1,3-benzoxadiazole (NBD). The lysosomal targeting group was morpholine. Fluorescence emission was measured to assess the probe's performance. The probe's selectivity and sensitivity were evaluated using fluorescence spectroscopy. The detection limits were calculated based on the fluorescence response. The probe's ability to target lysosomes was confirmed through cellular imaging experiments. The study combined synthetic chemistry with fluorescence-based analytical methods.

The NBD-B-T probe demonstrated fluorescence emission turn-on performance when detecting Cys and Hcy. The detection limits were measured at 76.0 nM for Hcy and 97.6 nM for Cys. The probe showed high stability and selectivity in detecting these biothiols. The morpholine group effectively targeted lysosomes in living cells. The probe's fluorescence increased significantly upon binding to Cys and Hcy. The low detection limits indicate the probe's sensitivity. The probe's performance was compared to other methods, showing superior selectivity. The results suggest that NBD-B-T is suitable for lysosome-specific detection of Cys and Hcy.

The NBD-B-T probe successfully combines lysosomal targeting with high selectivity for Cys and Hcy detection. The probe's fluorescence emission increased upon binding to these biothiols. The detection limits were among the lowest reported for similar probes. The morpholine group was essential for lysosomal targeting. The probe's stability and sensitivity were confirmed through experiments. The results suggest that NBD-B-T is effective for detecting Cys and Hcy in living cells. The probe's performance supports its use in cellular imaging studies. The findings align with the authors' stated goals of developing a lysosome-targeted probe.