Lighting up cysteine and homocysteine in sequence based on the kinetic difference of the cyclization/addition reaction

Abstract

A novel one- and two-photon fluorescent probe CB1 has been developed for discriminating Cys and Hcy in a successive manner with high selectivity. The discrete time-dependent fluorescent responses enable us to sequentially detect Cys and Hcy in different time windows. Two-step reaction and kinetic modes were used to explain the sensing mechanism. As a promising biosensor for cell imaging, CB1 has been confirmed to exhibit membrane permeability to intact cells, low cytotoxicity to viable cells and photostability to ultraviolet light excitation. Furthermore, the results from the control assay have shown that the one- and two-photon fluorescence of CB1 within cells is associated with intracellular mercapto biomolecules but yet there is little interference with physiological pH value, viscosity and common bioanalytes. Finally one- and two-photon fluorescent images of CB1 within living SiHa cells have been presented.

Synthesis and Application of an Aldazine-Based Fluorescence Chemosensor for the Sequential Detection of Cu2+ and Biological Thiols in Aqueous Solution and Living Cells

“…Fluorescence-based methods using responsive chemosensors have long been recognized as one of the most promising techniques for thiol detection due to their high sensitivity, selectivity, simplicity of operation and potential application in living cell imaging. In the past few years, various fluorescent chemosensors to detect biothiols have been developed by exploiting diverse reaction mechanisms, including Michael addition [ 39 , 40 ], cyclization reactions with aldehyde [ 41 , 42 ], cleavage reactions by thiols [ 43 , 44 ], and others [ 45 , 46 ].…”

Visual Discrimination of Homocysteine from Cysteine through Selective Fluorescent Gel Formation

“…In contrast to Cys, a few methods enabled the selective discrimination of Hcy. They were based on chemical reactions and aggregation of gold nanoparticles . It is still necessary to develop a reliable strategy for distinguishing Hcy from Cys.…”

A Copper (II) Ensemble-Based Fluorescence Chemosensor and Its Application in the ‘Naked–Eye’ Detection of Biothiols in Human Urine

“…Among various conventional methods such as electrochemical approaches [15,16], high-performance liquid chromatography (HPLC) [17,18], gas chromatography [19,20] and mass spectrometry (MS) [21], fluorescence analysis using a responsive molecular probe or chemosensor has been recognized as one of the most promising approaches due to its excellent sensitivity, selectivity, and capability of detecting analytes in live biological specimens [22][23][24][25][26]. To date, a large number of fluorescence chemosensors aiming to distinguish biothiols from other amino acids and bioactive species have been developed based on several sensing mechanisms: (1) Michael addition [27][28][29]; (2) cyclization with aldehyde [30,31]; (3) the cleavage of sulfonamide, sulfonate esters, selenium-nitrogen bonds and disulfide bonds [32][33][34][35][36][37][38]; (4) intramolecular elimination [39,40].…”