Construction And Application Of A Novel Amperometric Electrochemical Biosensor

Because of the advantages of simple,fast,sensitive and efficient of an electrochemical sensor,it is widely used in many fields.Such as drug quality control,toxic substances detection,food safety,disease marker detection and drug metabolism research.In terms of the electrochemical sensors,there are various classification standards.According to the different detecting substances,they are divided into biosensors,ion sensors,gas sensors,etc.It also could be divided into conductometric,amperometric,potentiometric and capacitive sensor according to the different output signal.Therefore,the amperometric biosensor is a kind of sensor that detects the biomolecules with the change of current as the output signal.In recent years,nanomaterials have rapidly developed into an important field of science and technology.Novel amperometric electrochemical biosensors based on various nanomaterials have been widely developed and applied to promote the development of human society.This paper is divided into four chapters,which are the introduction part,self-assembled microgels for sensitive and low-fouling detection of streptomycin in complex media,label-free electrochemical DNA biosensor for kanamycin detection based on the diblock DNA,electrochemical aptasensor for ultrasensitive detection of adenosine triphosphate based on the DNA-templated copolymer assembly amplifying signal.Chapter?:IntroductionIn this chapter,the concept and classification of electrochemical sensors were briefly summarized,and the development of amperometric biosensors and their applications in food safety and biomolecule detection were mainly reviewed.Chapter?:Self-assembled microgels for sensitive and low-fouling detection of streptomycin in complex media.In terms of detection of antibiotic within complex media,the nonspecific adsorption is an enormous challenge and antifouling sensing interfaces capable of reducing the nonspecific adsorption from complex biological samples are highly desirable.In this work,a novel anti-fouling electrochemical immunosensor was explored based on the self-assemble of two kinds of poly?N-isopropylacrylamide??P?NIPAm??microgels on the surface of graphene oxide?GO?for sensitive detection of streptomycin?STR?.The microgels modified with glycidyl methacrylate?GMA?and zwitterionic liquid1-propyl-3-vinylimidazole sulfonate?PVIS?were prepared respectively.The microgels with GMA were used by combining of specific recognition of anti-STR.The rapidly specific binding of antigen and anti-STR resulted in a decrease of current density to generate electrochemical responsive signals.Zwitterionic liquid modified microgels were used as the role of anti-fouling,which can form stronger hydration and show excellent antifouling ability.As a result,we achieved efficient and sensitive detection for STR in complex sample with evidently resisted nonspecific adsorption effect,the wide linear range towards STR was from 0.05 ng mL^-1 to 100 ng mL^-1,with a detection limit down to 1.7 pg mL^-1.The immunosensor based on the surface functionalization of microgels showed promising applications for the detection of antibiotics in complex media.Chapter?:Label-free electrochemical DNA biosensor for kanamycin detection based on diblock DNA.It is urgent to develop a more simple and sensitive method to detect antibiotic residues considering the harm of antibiotic residues in food to human body.Herein we designed a label-free electrochemical DNA biosensor for sensitive detection of kanamycin?KAN?based on diblock DNA with 15-mer of poly-cytosine?poly-C?.The diblock DNA can be immobilized to graphene oxide?GO?due to strong physical adsorption between the 15-mer of poly-C and GO.The aptamer of KAN acted as the other block used for rapidly binding the target.It can specifically capture the target,which leads to the change of electrochemical signal.Consequently,the DNA biosensor exhibited high sensitivity and specificity towards KAN,the linear range was from 0.05 pM to 100 nM with a detection limit of 0.0476 pM.The developed DNA biosensor was constructed easily and showed promising applications for the detection of antibiotic residues in food safety.Chapter?:Electrochemical aptasensor for ultrasensitive detection of adenosine triphosphate based on the DNA-templated copolymer assembly amplifying signal.As a small biological molecule,Adenosine triphosphate?ATP?plays a vital role in regulating cellular metabolism processes.Accurate and sensitive analytical techniques for detecting ATP are urgently needed.Herein,a novel electrochemical aptasensor was designed based on DNA-templated copolymers for sensitive detection of ATP.These DNA-templated copolymers were constructed through hybridization chain reaction?HCR?to amplify the electrochemical response signals.The ATP aptamer modified by the electronic medium ferrocene could be regarded as a“bridge”connecting two DNA-templated copolymers.In the presence of ATP,extraordinary binding selectivity of DNA-templated copolymers for target ATP,and the rapid electron transfer of ferrocene were beneficial to the sensitive detection of target ATP.Consequently,the developed novel aptasensor exhibited a wide linear range toward ATP was from 0.1 pM to 10000 pM,and high selectivity with a detection limit down to 11.5 fM.The electrochemical aptasensor indicated promising applications for the detection of biological small molecule in living organisms.