Near-Infrared Probes for Biothiols (Cysteine, Homocysteine, and Glutathione): A Comprehensive Review

Abstract

Biothiols (cysteine, homocysteine, and glutathione) are an important class of compounds with a free thiol group. These biothiols plays an important role in several metabolic processes in living bodies when present in optimum concentration. Researchers have developed several probes for the detection and quantification of biothiols that can absorb in UV, visible, and near-infrared (NIR) regions of the electromagnetic spectrum. Among them, NIR organic probes have attracted significant attention due to their application in in vivo and in vitro imaging. In this review, we have summarized probes for these biothiols, which could work in the NIR region, and discussed their sensing mechanism and potential applications. Along with focusing on the pros and cons of the reported probes we have classified them according to the fluorophore used and summarized their photophysical and sensing properties (emission, response time, limit of detection).

Next-Generation Femtech: Urine-Based Cervical Cancer Diagnosis Using a Fluorescent Biothiol Probe with Controlled Smiles Rearrangement

“…14−16 Biothiols comprise three distinct entities: cysteine (Cys), homocysteine (Hcy), and glutathione (GSH). 17 by employing chemical moieties, this approach has encountered resistance due to its reliance on chemical reactions [i.e., Smiles rearrangement reaction (SR) and Thiol-Michael's addiction (MA) reaction]. 18−20 There are many fluorescent probes to detect biothiol molecules (Table S1).…”

“…In this work, we introduced a novel femtech, which is a simple, straightforward, and readily applicable urine-based diagnostic method for cervical cancer, using a fluorescent biothiol probe (Figure b). Many reports for fluorescence sensing of biomarkers containing biothiol in urine samples have been disclosed. − Among them, the monitoring of biothiol has gained significance in the clinical diagnosis fields as the thiol group (-SH) is highly associated with the antioxidant process during the early stage of various diseases, such as neurological disorders, stress-induced disorders, and cancer. − Biothiols comprise three distinct entities: cysteine (Cys), homocysteine (Hcy), and glutathione (GSH) . Given the need to precisely monitor each thiol group, differentiating Cys from Hcy within the thiol mixture presents a challenge due to their structural resemblance.…”

Simple and Cost-Effective Quantum Dot Chemodosimeter for Visual Detection of Biothiols in Human Blood Serum

“…Various approaches for qualitative as well as quantitative analysis of these bioanalytes have been developed, mainly based on electroanalytical techniques, , high-performance liquid chromatography (HPLC), , capillary electrophoresis separation, immunoassays based on derivatization with fluorescent/phosphorescent reagents, spectrophotometric methods, etc. , Unfortunately, all of these methods require either expensive reagents or equipment or skilled manpower to ensure reproducibility. In this context, much attention is being paid to the development of simple and cheap fluorescent probes, without compromising selectivity and sensitivity. − Nanoparticles have been proven to be an efficient substitute for organic fluorophores, particularly for developing emission “turn on/off” sensors. − Among various nanoparticles, quantum dots (QDs) are of particular interest in developing novel biosensors owing to their unique properties such as broad absorption band, emission in the visible region, photostability, etc. − Moreover, the potential of QDs to transfer electrons or holes to biologically important molecules, interacting covalently or noncovalently with their surface, can be used to tune the QD emission intensity and thus generate charge transfer-based emission “on/off” signaling. − …”

Metal-assisted core–shell plasmonic nanoparticles for small molecule biothiol analysis and enantioselective recognition

“…Various methods have been reported for analyzing biothiols and differentiating Cys enantiomers in food or biological samples, including mass spectrometry, near infrared (NIR), electrochemical, fluorescence, and high-performance liquid chromatography (HPLC). [13][14][15][16][17][18] These methods not only require complex pre-processing and expensive instrumentation but also cause unavoidable signal interference and loss. Therefore, the development of a fast, simple, and anti-interference determination method is important for a broad range of applications.…”