Abstract
In this work, a sensitive and selective turn-on fluorimetric method has been developed for the determination of biothiols based on blocking Ag+-induced fluorescence quenching of nitrogen-rich polymer carbon nanostrips (NRPCNSs). Ag+ion can induce the fluorescence quenching of NRPCNSs due to the formation of nonfluorescent coordination complexes via robust Ag-N interaction. Once addition of biothiols, such as cysteine (Cys) and glutathione (GSH), Ag+ions prefer to interact with biothiols rather than NRPCNSs, which could be attribute to the formation of Ag-S bond, thus leading to effective fluorescent recovery of NRPCNSs. Under the optimized conditions, excellent linear relationships existed between the recovery degree of the NRPCNSs and the concentrations of Cys and GSH in the range of 0.05 μM to 10 μM and 0.2 μM to 30 μM, respectively. And, the limits of detection (LODs) for Cys and GSH are 16.5 nM and 65.1 nM, respectively. The detection system also shows high selectivity against other non-thiol amino acids. Moreover, the potential in practical applications of this proposed method has been demonstrated by detecting biothiols in human serum and fluorescence imaging of biothiols in living cells.
Highlights
Over the years, biological thiols, generally refering to cysteine (Cys), homocysteine (Hcy), and glutathione (GSH), have drawn considerable attention due to the essential roles played by these molecules in biological systems [1,2,3]
In the presence of biothiols, because of a lone pair of electrons from sulfur entered the low-lying vacant d orbitals from silver [41, 42], the Ag-S bond could be formed based on the strong binding preference between Ag+ ion and thiol groups, leaving little or no chance for Ag+ ion binding on the nitrogen-rich polymer carbon nanostrips (NRPCNSs). us, we reasoned that weakly forming Ag+-NRPCNSs metal complexes would display intense fluorescence in the presence of biothiols, and the corresponding turn-on fluorescent response can be used for quantitatively screening of biothiols through fluorescent spectroscopy
As proposed, when an appropriate amount of Ag+ ion is added to the NRPCNSs solution, the fluorescence is dramatically quenched by Ag+ ions (Figure 1(b)). is clearly demonstrates that the Ag+ ions induces the formation of nonfluorescent Ag+NRPCNSs coordination complexes by the electron or energy transfer mechanism, leading to the quenching of NRPCNSs fluorescence
Summary
Biological thiols (biothiols), generally refering to cysteine (Cys), homocysteine (Hcy), and glutathione (GSH), have drawn considerable attention due to the essential roles played by these molecules in biological systems [1,2,3]. Numerous researches have proved that the imbalance of biothiols in biological systems is connected with specific pathological conditions and many human diseases. Elevated concentrations of Hcy are involved in many diseases, such as cardiovascular diseases, osteoporosis, dementia, and Alzheimer’s disease [7]. Among these biothiols, GSH, as the most predominant and abundant intracellular nonprotein thiol, is critical for numerous cellular functions, such as enzyme catalysis, apoptosis, protein synthesis, and transmembrane transport [8]. Since the levels of these thiol compounds in human biological samples (such as plasma, live cells, or urine) have important reference value for clinical diagnosis of various diseases [11, 12], it is of great importance and significant interest to develop methods for sensitive, selective, and effective detection of biothiols in biosamples
Sign-in/Register to view highlights & summary 
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call