| Bio-thiol molecules mainly include glutathione(GSH),cysteine(Cys)and homocysteine(Hcy)in biological systems.They play a significant role of scavenging free radicals,detoxifying and anti-aging in the human body.It is found that the changes in the content of Mercaptan molecules are related to Parkinson,Alzheimer and other serious diseases.Therefore,the accurate detection of bio-thiol molecules in human body is of great significance in health assessment and disease treatment.Fluorescence sensors have attracted wide attention in recent years due to their advantages of real-time response,high sensitivity,selectivity and easy-operation in comparison with traditional probes.Metal-organic frameworks(MOFs),as a new type of fluorescence probe,can further improve the sensitivity and shorten the response time.At the same time,the rigid structure of MOFs can effectively avoid cluster quenching effect and improve the detection accuracy.In this paper,three water-stable MOF-based fluorescence probes were designed and synthesized for the detection of bio-thiols with high selectivity.Main methods include selecting the ligand containing specific functional groups,post-modification methods,using host-guest interaction in MOFs and so on.A water-stable zirconium-based MOF UiO-67-sbdc is synthesized by solvothermal method using H2sbdc as organic ligand.UiO-67-sbdc exhibits a "Turn-on" response in the detection of GSH with high selectivity.Its detection mechanism is the push-pull electronic effect between the sulfhydryl group and peptide bonds on GSH and the carbon-carbon double bonds on the ligand.The probe is not interfered by other amino acid molecules(including cysteine)and common ions in the human body,and it is insensitive to environmental changes(such as pH,temperature and so on).Thus,it can be used in human detection.Further studies prove that UiO-67-sbdc can realize the selective recognition of GSH in scrum and have its potential medical applications.UiO-67-bpydc is synthesized by using H2bpydc as organic ligand.A post-modified MOFs fluorescent probe Eu3+/Cu2+@UiO-67-bpydc with rare earth ions as luminescent center is obtained by chelating Eu3+ and Cu2+ on ligands.The probe uses Cu2+ as the specific recognition site for sulfhydryl groups,and the coordination reaction between Cu2+ and sulfhydryl group can recognize GSH in aqueous solution with "Turn-on"response,and the fluorescence from Eu3+ can eliminate the interference from amino acids.In the simulated physiological environment,Eu3+/Cu2+@UiO-67-bpydc can detect GSH with enhanced fluorescence detection limit of 68.0 nM(the normal concentration of extracellular GSH is about 20 μM),which indicates the possibility of using this MOF-based probe in biological samples,offering a new method for the diagnosis of such neurological disorders as depression and autism.A new Zn-based MOFs material ZJU-204 is prepared by hydrothermal method using H2dtba which contains disulfide bonds as the organic ligand.The fluorescence of the material comes from H2dtba ligand.The framework structure has excellent water stability and thermal stability.GSH and Cys in aqueous solution can be recognized from each other according to their different emission peak intensity and wavelength,while other biomolecules have little influence on the detection results.For the first time,the selective recognition between GSH and Cys using a MOF-based fluorescence probe has been realized,which is of great value in disease diagnosis and medical research. |
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