Point-of-Care Testing Strategies Based On The Catalytic Activity Regulation Of Gold Nanoparticles Nanozymes

Gold nanomaterial-based nanozyme is one of the important branches of nanozymes It is not only widely used in the photodynamic therapy,but also plays an important role in point-of-care target detection.However,the catalytic activity of gold nanozymes was related to the pH in sensing systems,especially the low catalytic activity at neutral conditions.To this end,the activity of these nanozymes needs to be regulated to meet the needs of fast,efficient and on-site testing in medical diagnosis and biological analysis under physiological conditions.Besides,the development of simpler,faster,and more sensitive point-of-care sensors with other simple signal readouts except color readout is also a huge challenge.Based on this,this paper designed two colorimetric and photothermal point-of-care sensing platforms on basis of regulating nanozyme activities of gold nanoparticle and successfully applied to the analysis of disease-related enzyme and metal ion sensingThe main content of this paper1.The development,catalytic mechanism and activity regulation strategy of gold nanozymes were summarized,and the characteristics,classification and development of point-of-care analysis were explained2.A new strategy for significantly accelerating the catalytic activity of?-CD@AuNPs at neutral pH was proposed based on regulating the peroxidase-like activity of ?-CD@AuNPs by Cu2+.In this system,inorganic pyrophosphate ions(PPi)coordinated with copper ions(Cu2+)and form Cu2+-PPi complex.Inorganic pyrophosphatase(PPase)as a target analyte,can hydrolyze PPi into inorganic phosphate(Pi)and release free Cu2+,which further resulting in a successful Cu2+-regulated peroxidase-like activity of ?-CD@AuNPs through the surface chemistry.As a result,lots of reactive oxygen radicals(ROS)generated,thus accelerating the enhancement effect of catalytic activity for the oxidation of peroxidase substrate 3,3',5,5'-tetramethylbenzidine(TMB).Based on this phenomenon,the colorimetric and photothermal detection of PPase at neutral pH was developed,with a detection limit of 0.07 mU·mL-1 and 0.10 mU·mL-1 for UV-vis absorbance and temperature readout,respectively.3.A novel colotimetric and photothermal system for detecting mercury ions in human serum was built,relying on an aggregation-activated oxidase-like activity of gold nanoparticles.The existing form of ?=BCD@AuNPs by the addition of Hg2+,so that dispersed ?-BCD@AuNPs could aggregate rapidly.The resultantly aggregated?-CD@AuNPs nanozymes exhibited high oxidase-like activity toward the oxidation of oxidase substrate TMB in the presence of dissolved oxygen(O2),resulting in the generation of singlet oxygen(102)and the finally successful formation oxidation products of TMB(TMBox).Based on color and photothermal effect of TMBox,a double-signal point-of-care sensing platform for Hg2+was successfully constructed Among them,the detection limit of Hg2+by colorimetric method is 0.147 ?M;the detection limit of Hg2+by photothermal method is 0.06 ?M.