Detection Of Reactive Oxygen Species Based On Solvent And Ion Effects On Gold Nanoclusters

In recent years,noble metal nanoclusters have attracted extensive attention due to the unique optical properties.Compared with conventional fluorescent materials,fluorescent gold nanoclusters(AuNCs)possess attractive characteristics such as ultra-small size,low toxicity,extraordinary optical stability,predominant biocompatibility,high luminous efficiency and facile surface modification,which endow their promising applications in biomedicine and chemistry fields.Reactive oxygen species(ROS)are important signaling molecules in living organisms that are generated in metabolic processes and play key roles in regulating a wide range of physiological functions.But,the overaccumulation of ROS also leads to oxidative stress and is associated with many pathological conditions.In this work,based on the unique optical properties and advantages of AuNCs,the detection of hydrogen peroxide,quinone compounds and hydroxyl radical scavengers was investigated.The main research work is as follows:1.We investigated the different organic solvents and metal ions-induced fluorescence changes of glutathione-protected gold nanoclusters(GSH-AuNCs),and the optimal luminescence conditions were optimized based on the solvent and ion effects of GSH-AuNCs.We found the fluorescence of GSH-AuNCs was significantly quenched in the presence of p-benzoquinone.Quinone compounds are an electrophilic substance that acts as an indirect antioxidant with detoxification.Further research on the effects of other quinone compounds on GSH-AuNCs fluorescence showed that the fluorescence intensity of GSH-AuNCs was significantly decreased in the presence of benzoquinone and naphthoquinone.But the results suggested that the detection selectivity of the method needs further optimization and improvement.2.The method for the detection of free radical scavengers was developed based on the fact that the fluorescence of GSH-AuNCs can be quenched by hydroxyl radical.The fluorescence intensity of GSH-AuNCs was significantly enhanced by the solvent effect of dimethyl sulfoxide and ion effect of aluminium ion,which makes the fluorescence quenching more apparent to improve the sensitivity of the detection of free radical scavengers.It was successfully applied to the detection of free radical scavengers and assess the total free radical scavenging ability of Ginkgo biloba extract.3.The fluorescence of chonaroitin sulfate-stabilized gold nanoclusters(CS-AuNCs)can be quenched by hydrogen peroxide-sensitive enlarged poly-(vinylpyrrolidone)-protected gold nanoparticles(PVP-AuNPs),which can be used for selective determination of uric acid(UA)and hydrogen peroxide(H2O2).The PVP-Au seeds could be synthesized simply by mixing PVP and HAuCl4,and PVP acted as reductant.The dimension of Au seeds can be further enlarged in the presence of UA/uricase or H2O2,which can readily reduce HAuCl4 catalyzed by the PVP-Au seeds,leading to the enlargement of PVP-Au seeds to obtain the PVP-AuNPs.The fluorescence of CS-AuNCs was quenched by PVP-AuNPs through the inner filter effect(IFE).Under the optimized conditions,the linear range of H2O2 is 1-100 μM with a detection limit down to 0.33 μM,and the linear range of UA is 5-100 μM with a detection limit down to 1.7μM.