A fluorescent probe emitting in near-infrared region for sensitive and selective detection of biothiols in both solution and living cells

Recent Research Progress of Red-Emitting/Near-Infrared Fluorescent Probes for Biothiols

Small-molecule biological thiols, including cysteine (Cys), homocysteine (Hcy) and glutathione (GSH), occupy a vital position in physiological and pathological activities. Abnormal fluctuations of their concentrations are often closely connected with...

A novel naphthalene-based fluorescent probe for highly selective detection of cysteine with a large Stokes shift and its application in bioimaging

An efficient naphthalene-based fluorescent probe (BTNA) for cysteine (Cys) has been rationally designed and synthesized in this work, which consists of a 6-(2-benzothiazolyl)-2-naphthalenol (BNO) fluorophore connected with an acrylate group (the fluorescence quenching and response group).

Fluorescent Probes with Multiple Binding Sites for the Discrimination of Cys, Hcy, and GSH

Biothiols such as cysteine (Cys), homocysteine (Hcy), and glutathione (GSH) play crucial roles in maintaining redox homeostasis in biological systems. This Minireview summarizes the most significant current challenges in the field of thiol-reactive probes for biomedical research and diagnostics, emphasizing the needs and opportunities that have been under-investigated by chemists in the selective probe and sensor field. Progress on multiple binding site probes to distinguish Cys, Hcy, and GSH is highlighted as a creative new direction in the field that can enable simultaneous, accurate ratiometric monitoring. New probe design strategies and researcher priorities can better help address current challenges, including the monitoring of disease states such as autism and chronic diseases involving oxidative stress that are characterized by divergent levels of GSH, Cys, and Hcy.

Reversible Absorption and Emission Responses of Nile Blue and Azure A Derivatives in Extreme Acidic and Basic Conditions

Oxazinium derivatives have recently played an important role in bioanalysis attributing to the distinguished properties, thus a detailed study of the structure-property relationship is especially significant. Herein, pH-sensitive optical properties of Nile Blue (1a), N-monoalkyl-Nile Blue (1b) and Azure A (1c) have been carried out in extreme acid and base conditions. Dyes 1a and 1c showed colorimetric changes by the protonation of nitrogen atom in strong acidic condition (pH < 2.0), and dyes 1a - c exhibited colorimetric changes by equilibrium between amino and imide groups in very strong basic case (pH > 7.6). Besides, their fluorescent properties were closed to ON - OFF and OFF - ON emissions at 640-820 nm under strong acidic and basic conditions. Moreover, the absorption and emission properties were reversible, and there were no remarkable optical intensity changes of dyes 1a - c under subacidic and neutral solutions (pH = 3.0-7.0). The (TD) DFT calculations were used to optimize the most stable structures of their corresponding protonated and deprotonated forms, and their absorption and emission properties were also explained. Their fluorescent properties nearly ON-OFF and OFF - ON in strong acidic and basic conditions at near-infrared region will give the possible application in pH detection for extreme conditions. Graphical abstract ᅟ.