Preparation Of Electrochemical Biosensors Based On Metal Nanocomposites And Their Applications In Disease Detection

Diseases are one of the major threats to human health,among which diabetes and gastric cancer are the most harmful of two non-communicable diseases to Chinese people.It is reported that early diagnosis and timely treatment can not only reduce the pain caused by these diseases,but also increase the cure rate and survival rate.Electrochemistry is a science that studies the mutual transformation of electrical and chemical phenomena.Electrochemical biosensors have the advantages of excellent specificity,high reproducibility,good stability and simple experimental operation,which have been widely studied in biomedical engineering.Recently,metal nanomaterials are often applied in electrochemical biosensors due to the good electrical conductivity and easy chemical or biological modification.This paper mainly discusses the synthesis methods of two metal nanocomposites and their applications in electrochemical disease detection.First,AgNFs@BSA nanoflowers were prepared by hydrothermal method and redox method,and AgNFs-Pt@BSA nanocomposites were synthesized in one step through replacement reaction.The flower-like structures of AgNFs-Pt@BSA with dewdrop-like platinum nanoparticles decorated on the petal surface were characterized by means of TEM and SEM technology.In addition,GO-Au NSs nanocomposites were prepared by seed growth-mediated methods.The silk-like structures of GO-Au NSs nanocomposites with a large number of Au nanostars grown on the surface were characterized by TEM and SEM.Both composites possess good conductivity,wide surface area and numerous surface functional groups,which can be used as good electrochemical sensor materials.Secondly,AgNFs-Pt@BSA-based electrochemical nonenzymatic H₂O₂sensor has been fabricated for H₂O₂ detection,and a biosensor based on AgNFs-Pt@BSA/GA/GOD nanocomposites has been fabricated for glucose detection.AgNFs with wide surface areas resulted in a high electron conductivity;Pt nanoparticles further increased the electrocatalytic ability toward H₂O₂;BSA around AgNFs-Pt provided numerous functional groups to crosslink GOD via GA.The excellent electrochemical responses about as-prepared glucose biosensors were presented in a wide linear range of 1 to 14 m M with a low detection limit of 0.3 m M（S/N=3）.Thus,as-fabricated glucose biosensors exhibited favorable stability,repeatability and specificity,and have been successfully used to detect blood glucose level in human serum samples,which has certain reference significance for clinical blood glucose detection.Finally,a biosensor based on GO-Au NSs@rBSA-FA nanocomposites has been fabricated for gastric cancer cells detection.Similarly,GO-Au NSs had a wide surface area and plenty of Au nanostars,which led to a high electron conductivity;r BSA-FA linking on the surface of GO-Au NSs enhanced the specificity and biocompatibility.As-prepared cell biosensors exhibited the favorable electrochemical responses toward MGC-803 cells with a wide linear range from 7×10² to 7×10⁶ cell m L^-1with a low detection limit of 2×10² cell m L^-1（S/N=3）.Therefore,this study exhibits a potential value in clinical diagnosis of circulating tumor cells.