Au@Pt@Liposome With Photothermal Enhanced Peroxidase Like Activity In Dual Mode Detection

Enzymatic reaction is widely used in biosensing,molecular detection and other fields.However,traditional natural enzymes composed of proteins are susceptible to p H,temperature,etc.,which bring about no activity.Nanoenzyme is a kind of nanomaterial with catalytic activity simulating natural enzyme.Compared with natural enzymes,the nanoenzyme has stronger stability,higher catalytic activity,and more universal catalytic reaction conditions,but the small size of the nanoenzyme limits their further application against surface functionalization.Therefore,solving the above problems is a hot spot in the research of nanoenzyme.Liposome is hollow spherical vesicles with the characteristics of internal loading of drug molecules and surface modification,thus it can improve the problem of functionalization of nanomaterial.Nevertheless,the current study on the functionalization and catalytic activity regulation of nanoenzyme by liposomes is relatively limited.At the same time,most nanoenzyme materials focus on the colorimetric detection,but such a single test can easily lead to false positive results,ultimately affecting the accuracy of the test results.Therefore,liposome@Au@Pt（LAP）nanoenzyme is proposed in this paper,which improves the functionalization and catalytic activity of peroxidase and applies it to the dual-mode detection of H₂O₂and glucose detection.Compared with conventional methods,this method has the advantages of high sensitivity and fast analysis speed.The main contents of study are summarized as follows:（1）Using liposomes as templates,gold shell coated liposome（LA）nanoenzymes were prepared by chemical reduction method.Under normal temperature,LA nanoenzyme can catalyze H₂O₂ to produce hydroxyl radicals（·OH）with strong oxidation resistance,and oxidize the colorless substrate 3,3’,5,5’-Tetramethylbenzidine（TMB）to produce a blue product,ox TMB.Based on the color change of the system and the change in the absorption peak of ox TMB at 652 nm,the detection of H₂O₂ is realized.Based on the good response of LA to H₂O₂,the color detection of glucose was further completed,and glucose oxidase was encapsulated inside the liposome to achieve the functionalization of nano enzymes.Glucose oxidase can decompose glucose to produce gluconic acid and H₂O₂.Therefore,the concentration of glucose can be further determined based on the color change of the color system caused by H₂O₂.At the same time,near-infrared light acts as an exogenous aid to enhance the color development process.Under near-infrared laser irradiation with a wavelength of 808 nm,due to the photothermal effect,not only the color reaction speed is significantly increased,but also the controlled release of glucose oxidase can be achieved by heating up the liposome to rupture.In summary,the LA nanoenzyme has achieved photothermal enhanced colorimetric detection of H₂O₂ and glucose,exhibiting a faster color reaction speed and lower detection limits than Au NPs.（2）A layer of platinum nanoparticles was coated on the basis of LA to prepare LAP nanoenzyme.The colorimetric test found that the detection limit of LAP nanoenzyme for H₂O₂could reach 1μM.At the same time,the detection limit of LAP for glucose was reduced from5μM to 1μM compared to LA.Further introducing electrochemical detection,a colorimetric electrochemical dual mode sensor based on LAP nanoenzyme was constructed for the determination of H₂O₂ content.The cyclic voltammetric curve shows that LAP has better electrochemical activity than LA.Further analysis combined with colorimetric detection results makes the results more reliable and accurate.