title: Homogeneous electrochemical detection of ochratoxin A in foodstuff using aptamer-graphene oxide nanosheets and DNase I-based target recycling reaction.
abstract: A simple and feasible homogeneous electrochemical sensing protocol was developed for the detection of ochratoxin A (OTA) in foodstuff on the immobilization-free aptamer-graphene oxide nanosheets coupling with DNase I-based cycling signal amplification. Thionine-labeled OTA aptamers were attached to the surface of nanosheets because of the strong noncovalent binding of graphene oxide nanosheets with nucleobases and aromatic compounds. The electronic signal was acquired via negatively charged screen-printed carbon electrode (SPCE) toward free thionine molecules. Initially, the formed thionine-aptamer/graphene nanocomposites were suspended in the detection solution and far away from the electrode, thereby resulting in a weak electronic signal. Upon addition of target OTA, the analyte reacted with the aptamer and caused the dissociation of thionine-aptamer from the graphene oxide nanosheets. The newly formed thionine-aptamer/OTA could be readily cleaved by DNase I and released target OTA, which could retrigger thionine-aptamer/graphene nanocomposites with target recycling to generate numerous free thionine molecules. Free thionine molecules were captured by negatively charged SPCE, each of which could produce an electrochemical signal within the applied potentials. Under optimal conditions, graphene-based aptasensing platform could exhibit good electrochemical responses for the detection of OTA at a concentration as low as 5.6pg/mL. The reproducibility, precision and selectivity of the system were acceptable. Importantly, the method accuracy was comparable with commercialized OTA ELISA kit when using for quantitative monitoring of contaminated wheat samples.
authors.affiliation: Department of Chemistry and Chemical Engineering, Institute of Biotechnology, Xinxiang University, Xinxiang 453000, PR China. Electronic address: sunaili77@yeah.net.
authors.forename: Ai-Li
authors.initials: AL
authors.lastname: Sun
authors.affiliation: Department of Chemistry and Chemical Engineering, Institute of Biotechnology, Xinxiang University, Xinxiang 453000, PR China; Key Laboratory of Analysis and Detection for Food Safety (MOE & Fujian Province), Department of Chemistry, Fuzhou University, Fuzhou 350108, PR China.
authors.forename: Yan-Fang
authors.initials: YF
authors.lastname: Zhang
authors.affiliation: Department of Chemistry and Chemical Engineering, Institute of Biotechnology, Xinxiang University, Xinxiang 453000, PR China; Key Laboratory of Analysis and Detection for Food Safety (MOE & Fujian Province), Department of Chemistry, Fuzhou University, Fuzhou 350108, PR China.
authors.forename: Guo-Peng
authors.initials: GP
authors.lastname: Sun
authors.affiliation: Department of Chemistry and Chemical Engineering, Institute of Biotechnology, Xinxiang University, Xinxiang 453000, PR China.
authors.forename: Xuan-Nian
authors.initials: XN
authors.lastname: Wang
authors.affiliation: Key Laboratory of Analysis and Detection for Food Safety (MOE & Fujian Province), Department of Chemistry, Fuzhou University, Fuzhou 350108, PR China.
authors.forename: Dianping
authors.initials: D
authors.lastname: Tang
mesh_terms: D000818:Animals; D052157:Aptamers, Nucleotide / Q000737:chemistry*; D015374:Biosensing Techniques / Q000295:instrumentation*; D002417:Cattle; D003850:Deoxyribonuclease I / Q000737:chemistry; D055664:Electrochemical Techniques / Q000295:instrumentation*; D005504:Food Analysis / Q000295:instrumentation*; D005506:Food Contamination / Q000032:analysis; D006108:Graphite / Q000737:chemistry*; D057230:Limit of Detection; D008958:Models, Molecular; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D009793:Ochratoxins / Q000032:analysis*; D010087:Oxides / Q000737:chemistry; D010640:Phenothiazines / Q000737:chemistry; D015203:Reproducibility of Results; D014908:Triticum / Q000737:chemistry
chemical_list: D052157:Aptamers, Nucleotide; D009793:Ochratoxins; D010087:Oxides; D010640:Phenothiazines; C025589:ochratoxin A; D006108:Graphite; D003850:Deoxyribonuclease I; C009469:thionine
keywords: Aptasensor; DNase I-based target recycling; Graphene oxide nanosheets; Homogeneous electrochemical assay; Ochratoxin A