ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

An electrochemical aptasensor based on catalytic hairpin self-assembly and co-amplification of AuPd/Fe-MOF and Au/Cu₂O for ultrasensitive detection of Cd²⁺

Jintao He, Baozhong Zhang, Panpan Tian, Ying Li, Xiaolong Liu, Xinyue Ma, Min Lin, Huina Zhu, Hanyu Chen, Liping Li, and Baoshan He

College of Environmental Engineering, Henan University of Technology, Zhengzhou, People’s Republic of China

E-mail: zb-z01@163.com

Received: 11 April 2023  Accepted: 12 September 2023

Abstract:

Cadmium (Cd), a typical heavy metal not essential for the human body, can cause harm to the liver and kidneys upon exposure. Hence, rapid cadmium detection in the environment is of utmost importance. This research presents an effective approach for detecting divalent cadmium ions (Cd²⁺) using a sensitive dual hairpin (HP) electrochemical aptasensor. The aptasensor incorporates AuPd/Fe-MOF as signal labels and Au/Cu₂O as the substrate material, and the rapid detection of divalent cadmium ions (Cd²⁺) was based on catalytic hairpin self-assembly (CHA), as the recognition strategy. Au/Cu₂O increased the specific surface area of the electrode and provided abundant sites for capturing the complementary deoxyribonucleic acid (CDNA) probe. The electrochemical signal is then amplified through synergistic catalytic hydrogen peroxide with AuPd/Fe-MOF, thereby enhancing the aptasensor's sensitivity. Moreover, the dual HP design effectively reduces the likelihood of non-specific capture and minimizes false positives. In this study, various analytical techniques were utilized to characterize the material and evaluate the aptasensor's performance. The morphological characteristics of the material were observed using scanning electron microscopy (SEM). Energy-dispersive spectroscopy (EDS) and X-ray diffraction (XRD) were employed to analyze the elemental composition and distribution of the material, respectively. The electrochemical behavior of the sensor was studied using cyclic voltammetry (CV), while electrochemical impedance spectroscopy (EIS) helped understand the aptasensor's assembly process. Furthermore, the aptasensor's performance was assessed using differential pulse voltammetry (DPV). Under the optimized experimental conditions, the constructed sensor demonstrated effective detection of Cd²⁺ in the concentration range of 10^–4–10 µM, with a remarkably low detection limit of 2.27 × 10^–5 µM. The feasibility of the sensor was validated by successfully detecting Cd²⁺ in real water samples.

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Keywords: Electrochemical aptasensor; Aptamer; Catalytic hairpin self-assembly; AuPd/Fe-MOF; Au/Cu2O; Cadmium ions

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-023-03082-x

Chemical Papers 77 (12) 7577–7587 (2023)