Amplified impedimetric aptasensor combining target-induced DNA hydrogel formation with pH-stimulated signal amplification for the heparanase assay.
Herein, a novel electrochemical impedimetric biosensor for the heparanase (HPA) assay was developed based on target protein-induced DNA hydrogel formation, followed by pH-stimulation of the hydrogel density to increase the signal amplification. The method involved the synthesis of two different copolymer chains, consisting of two cooperatively functioning cross-linking elements, where one element was associated with the HPA-response and the other one with the pH-response. Initially, single-strand DNA as a capture probe was modified on the electrode surface. In the presence of HPA, the HPA-responsive element binding to HPA-induced DNA hybridization between the two copolymer chains and captured DNA, giving rise to the formation of a low-density polymer hydrogel film on the electrode surface and it obtaining an obvious impedimetric response. A significant signal enhancement was observed when changing the pH of the hydrogel film to 5.0, which could be ascribed to the fact that the pH-responsive element can fold into four-stranded i-motif structures at pH 5.0, leading to the increase in density of the hydrogel film. By implementing the DNA hydrogel to induce an impedimetric response change, this impedimetric biosensor exhibited an excellent analytical performance towards the HPA quantitative assay, with a low detection limit of 0.003 pg mL-1. This new method provides a versatile signal amplification method and paves a new way to construct impedimetric sensors for bioassays.
Key Laboratory of Luminescent and Real-Time Analytical Chemistry (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, PR China. yuanruo@swu.edu.cn yqchai@swu.edu.cn.
Zhe-Han
ZH
Yang
Key Laboratory of Luminescent and Real-Time Analytical Chemistry (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, PR China. yuanruo@swu.edu.cn yqchai@swu.edu.cn.
Ying
Y
Zhuo
Key Laboratory of Luminescent and Real-Time Analytical Chemistry (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, PR China. yuanruo@swu.edu.cn yqchai@swu.edu.cn.
Ruo
http://orcid.org/0000-0003-3664-6236
R
Yuan
Key Laboratory of Luminescent and Real-Time Analytical Chemistry (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, PR China. yuanruo@swu.edu.cn yqchai@swu.edu.cn.
Ya-Qin
YQ
Chai
D052157:Aptamers, Nucleotide; D015374:Biosensing Techniques; D004247:DNA / Q000737:chemistry*; D055664:Electrochemical Techniques; D005966:Glucuronidase / Q000737:chemistry*; D020100:Hydrogels; D006863:Hydrogen-Ion Concentration; D057230:Limit of Detection; D000099175:Heparanase
D052157:Aptamers, Nucleotide; D004247:DNA; D005966:Glucuronidase; D020100:Hydrogels; D000099175:Heparanase