Indirect Sensing Strategy Of Biomolecules Based On Enzymatic Reaction

Colorimetric and electrochemical sensors are two important parts in analytical chemistry.Due to their simple operation,fast response,and high sensitivity,they were widely used in environmental detection,food monitoring,and medical research.In recent years,the sensing of biomolecules has attracted the attention of many researchers,all of them hope to develop a variety of sensitive,practical and simple biomolecular sensors with advanced materials and simple analytical techniques.We designed several sensors for detecting small biomolecules based on indirect sensing strategies in this paper,including the following:1.Because of the specific binding of the indicator 1-chloro-2,4-dinitrobenzene（CDNB）to L-Cys（cysteine）to produce 2,4-dinitrophenylcysteine（DNPC）,and the sarcosine oxidase method releases calcium peroxide from sarcosine.We constructed a sensing platform for indirect detection of sarcosine with a detection limit of 20.4 nM.In addition,we also complete the detection of sarcosineby using mobile phone.2.Using the Fenton-like reaction and the uric acid oxidase method to produce hydrogen peroxide in uric acid,we designed a multi-color colorimetric sensing platform for indirect detection of uric acid,and the products were characterized by transmission electron microscopy（TEM）and energy dispersive spectroscopy（EDS）.In addition,we also used electrochemical methods to verify the sensing mechanism and compared the effects of indirect electrochemical sensing and direct electrochemical sensing on uric acid detection.Finally,we completed detection of actual sample bloodbased on visual sensors,and developed a test strip detection platform.3.Both of Prussian blue nanocubes（PBNCs）and molybdenum disulfide（MoS₂）are nanomaterials with peroxidase-like properties.We successfully prepared molybdenum disulfide-Prussian blue composite nanomaterials with peroxide mimetic properties by simple method,and characterized them by transmission electron microscopy（TEM）,energy dispersive spectroscopy（EDS）and X-ray Photoelectron Spectroscopy（XPS）.Due to the synergistic effect of Prussian blue and molybdenum disulfide,the enzymatic activity of the composite nanomaterials is greatly improved,which can effectively catalyze the hydrogen peroxide produced by the cholesterol oxidase method,and then we introduce 3,3’,5,5’-tetramethylbenzidine（TMB）as an electrochemical signal indicator,using the I-t curve to achieve high selectivity and high sensitivity indirect electrochemical detection of cholesterol.