Detection Of Biological Small Molecules GSH?Glucose And ATP Based On Peroxidase-Like Activity Of Precious Metals Nanoclusters

Natural enzyme is a kind of catalytic activity protein,but its stability is poor and is easily deactivated by the influence of external conditions.Therefore,artificial mimic enzymes have been paid attention.In recent years,precious metal nanoclusters?especially AuNCs?are widely used in biology,materials and medicine for their unique size effects,optical,magnetic and catalytic properties.In this paper,the performance of the mimic enzyme in gold nanoclusters is improved by doping the noble metal elements through synergistic action.At the same time,the selectivity of analysis and recognition is improved by surface functionalization.Three kinds of nanomaterials based on gold nanoclusters were synthesized.Using gold nanoclusters to simulate peroxidase activity,quantitative analysis methods for biothiol,glucose and ATP were established,respectively.The main contents are shown as follows:?1?On the basis of the inhibition effect of GSH on the peroxidase-like activity of GSH stabilized gold nanoclusters,here a novel and facile strategy for colorimetric detection of cellular GSH level was well established.In this sensing system,GSH caneffectivelyinhibittheoxidationofperoxidasesubstrate3,3',5,5'-tetramethylbenzidine?TMB?to produce a blue colored product.Under the optimized conditions,the absorbance at 652 nm against GSH concentration shows a linear relationship within a range from 2 to 25?M with detection limit of 0.42?M.This excellent property allows our approach to be used to accurately evaluate the cellular GSH levels,and it is revealed that the overall GSH level in cancer cells was much higher than that in normal cells.The presented assay will enable a powerful tool for identifying cancer cells in a simple manner for biomedical diagnosis associated with GSH.?2?This work presents a novel and facile strategy for the fabrication of gold–platinum bimetallic nanoclusters?Au–PtNCs?with adjustable Au/Pt molar ratios by a one-pot synthetic route.It was unexpectedly found that the prepared Au–PtNCs with an optimal Au/Pt molar ratio?1:1?could exhibit greatly enhanced peroxidase-like catalytic activity and chemical stability toward harsh conditions due to the synergistic effect of the two atoms,in contrast with pure AuNCs.These prominent advantages render Au–PtNCs capable of sensitive and selective colorimetric detection of glucose by means of a NCs–glucose oxidase?GOx?cascade-catalyzed system using 3,3',5,5'-tetramethylbenzidine?TMB?as a chromogenic substrate.This assay can be used not only for visual detection of glucose by the naked eye but for reliable and convenient quantification in the range from 5 to 55?M with a detection limit of 2.4?M.Importantly,to widen the application of point-of-care testing?POCT?of glucose to biomedical diagnosis,an integrated agarose hydrogel based sensing platform comprising NCs,GOx and TMB was rationally designed.It was demonstrated that this sensing platform could serve as a reagentless and instrument-free platform for direct visualization of glucose with different levels in human serum,as the results were in good accordance with those obtained from a free NC-involved detection system as well as from a commercial blood glucometer.?3?Adenosine triphosphate?ATP?,was required by almost all the living organisms,thus fluorescent probes for ATP levels fluctuation were essential and highly desired.Herein,a ratio fluorescence strategy was constructed for highly sensitive and selective detection of adenosine 5-triphosphate?ATP?with AuNCs^*built-in a metal-organic frameworks In-BDC.The immobilized AuNCs^*were functionalized with a 4-mercaptophenyl boronic acid?Phe?and a L-cysteine hydrochloride anhydrous?Cys?.The weak-fluorescent In-BDC-AuNCs^*gave strong fluorescence in the presence of H₂O₂ at 450 nm.Interestingly,with the addition of ATP,boronic acid can covalently bind to 1,2-diols,and electrostatic interactions between amino and phosphate groups function cooperatively to inhibit the oxidation of peroxidase In-BDC,leading to the corresponding reduction of fluorescence intensity,which could be utilized to detect ATP with a linear range of 5-25?M and a detection limit of 1.4?M.