Biosensing Analysis Based On Atom Transfer Radical Polymerization

Electrochemical biosensor is widely used in quantitative detection of various biomarkers due to its miniaturization,simple operation and high sensitivity.Biomarkers are specific biomolecules that can mark changes in the corresponding physiological conditions caused by changes in the structure of tissues,organs,cells.Biomarkers include enzymes,DNA,and so on.Biomarkers are closely related to many important diseases,and these biomarkers are extremely low in the early stages of diseases.As medicine steadily progresses towards specific treatments based on biological targets,it is important to achieve ultrasensitive detection of biomolecules.1.In this work,electrochemically mediated atom transfer radical polymerization?eATRP?was used for glucose ultrasensitive detection mediated for the first time.First,4-mercaptophenylboronic acid was immobilized on the surface of Au electrode by Au-S bond,and borate can specifically recognize 1,2-o-hydroxyl groups of glucose.Bromoisobutyryl bromide reacts with remaining hydroxyl groups of glucose to form alkyl halide initiation site of ATRP.The copper catalyst is activated by electrochemical method,and monomer of ATRP begins to graft onto the surface of the Au electrode to form polymer chains labeled with ferrocene.The electrochemical signal of ferrocene was quantitatively measured by square wave voltammetry.Under optimal conditions,this method can detect glucose with a low limit of detection of 0.32 nM?R²=0.996?.In addition,the strategy also has a good specificity for glucose detection under physiological conditions and high reliability in human serum.2.In this work,a highly efficient and simple method based on bisPNA for quantitative detection of a specific dsDNA"plasmid DNA pBR322"by electrochemical impedance spectroscopy?EIS?was reported.First,the bisPNA probe was attached to the surface of Au electrode by Au-S bond.In the bisPNA,all cytosines?C?were replaced by pseudoisocytosine"J",and one strand of plasmid hybridized with bisPNA to form a stable PNA.DNA-PNA trimer helix by Watson-Crick and Hoogsteen.This bisPNA probe then directly recognized pBR322based on PNA.DNA-PNA invasion of the triplex without dsDNA denaturation.The redox electroactive probe[Fe?CN?₆]^3-/4-acts as an indicator,electrochemical impedance spectroscopy was applied to measure the charge resistance(R_ct)between electrode surface and electrolyte,and limit of detection was 0.1 nM?R²=0.993?.Based on the principle of bisPNA-based recognition plasmid,we can apply ATRP to detection of plasmid DNA to achieve ultrasensitive of plasmid in the future.