Construction Of Glutathione And Cysteine Responsive Fluorescent Probes And Their Sensing Detection Studies

Biothiols play an irreplaceable role in maintaining the normal physiological metabolism of the human body,and their levels in the organism are closely related to the health level of the human body.Among them,glutathione（GSH）,a biothiol,has good antioxidant properties and is one of the functional factors commonly used in nutraceuticals.Therefore,accurate quantification of GSH in health food and precise monitoring of biothiols in serum can protect food quality control and human health.With the development of nanotechnology,fluorescent probe technology based on noble metal nanomaterials is one of the highly sensitive detection strategies that have been rapidly developed and applied in the last decade or so,providing highly sensitive identification and detection of biothiols,while breaking through the traditional gold nanoclusters（AuNCs）with low luminescence intensity and the inability of many probes to specifically distinguish between different types of biothiols.In this paper,we present a study on the high sensitivity of biothiols to the detection of biothiols.In this thesis,two fluorescent probes were developed for the rapid detection of biothiols by the domain-limited fluorescence enhancement phenomenon and the ratiometric fluorescence technique,and two probes were used for the detection of biothiols in serum and the quantitative assessment of GSH in nutritional supplements,respectively.The main studies and results are as follows:1.A new type of AuNCs with improved fluorescence emission efficiency was synthesized by using GSH as a reducing agent with the spatial restriction effect of the metal-organic framework ZIF-8.A novel"on-off-on"fluorescence assay was developed for the highly sensitive and rapid detection of biothiols in serum.The established fluorescent probes responded to GSH and cysteine（Cys）in the linear ranges of 1.5～8μmol/L and 1～10μmol/L,respectively,with limits of detection（LOD）of 0.32μmol/L and 0.15μmol/L,respectively,and spiked recoveries in the range of 97.36%～115.31%.The limits of detection（LOD）were 0.32μmol/L and 0.15μmol/L,respectively,and the spiked recoveries ranged from 97.36%to 115.31%,which provided a validated methodology for rapid analysis and screening of total biothiols.2.In order to specifically distinguish between different species of biothiols and resolve the interference of cysteine in fluorescence detection,a ratiometric fluorescent probe BR-CDs that specifically responds to GSH without Cys interference was constructed in this thesis using physical hybridization of blue-emitting carbon dots（B-CDs）and red-emitting carbon dots（R-CDs）.The probe showed a decrease in red-emission intensity and recovery of blue-emission intensity in the presence of GSH,while the ratio of dual-emission fluorescence intensity of the probe,FL₄₄₀/FL₆₂₀,showed a superior linear response to GSH in the range of30～500μmol/L with a LOD of 5.27μmol/L.Selective experiments showed that the BR-CDs hybrid probes could distinguish well between GSH and other biothiol small molecules,and did not produce signal responses for the other eight essential amino acids with good specificity.The recoveries of GSH spiked in mineral water using this method were 87.87%～100.25%,showing great potential for the quantitative assessment of GSH specificity.