title: A label-free electrochemical biosensor for highly sensitive and selective detection of DNA via a dual-amplified strategy.
abstract: In this work, by combining the enzymatic recycling reaction with the DNA functionalized gold nanoparticles (AuNPs)-based signal amplification, we have developed an electrochemical biosensor for label-free detection of DNA with high sensitivity and selectivity. In the new designed biosensor, a hairpin-structured probe HP was designed to hybridize with target DNA first, and an exonuclease ExoIII was chosen for the homogeneous enzymatic cleaving amplification. The hybridization of target DNA with the probe HP induced the partial cleavage of the probe HP by ExoIII to release the enzymatic products. The enzymatic products could then hybridize with the hairpin-structured capture probe CP modified on the electrode surface. Finally, DNA functionalized AuNPs was further employed to amplify the detection signal. Due to the capture of abundant methylene blue (MB) molecules by both the multiple DNAs modified on AuNPs surface and the hybridization product of capture DNA and enzymatic products, the designed biosensor achieved a high sensitivity for target DNA, and a detection limit of 0.6 pM was obtained. Due to the employment of two hairpin-structured probes, HP and CP, the proposed biosensor also exhibited high selectivity to target DNA. Moreover, since ExoIII does not require specific recognition sequences, the proposed biosensor might provide a universal design strategy to construct DNA biosensor which can be applied in various biological and medical samples.
authors: The Key Laboratory of Life-Organic Analysis, College of Chemistry and Chemical Engineering, Qufu Normal University, Qufu Shandong 273165, PR China; State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, PR China.
authors: Rong-Mei
authors: RM
authors: Kong
authors: State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, PR China.
authors: Zhi-Ling
authors: ZL
authors: Song
authors: State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, PR China.
authors: Hong-Min
authors: HM
authors: Meng
authors: State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, PR China. Electronic address: xiaobingzhang89@hotmail.com.
authors: Xiao-Bing
authors: XB
authors: Zhang
authors: State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, PR China.
authors: Guo-Li
authors: GL
authors: Shen
authors: State Key Laboratory for Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, PR China.
authors: Ru-Qin
authors: RQ
authors: Yu
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D004247:DNA / Q000032:analysis*; D055664:Electrochemical Techniques / Q000379:methods*; D006046:Gold / Q000737:chemistry*; D057230:Limit of Detection; D053758:Nanoparticles / Q000737:chemistry*
chemical_list: D006046:Gold; D004247:DNA
keywords: DNA detection; Enzymatic recycle; Gold nanoparticles; Label-free; Signal amplification