Target-induced Strand Displacement-based Electrochemical Aptasensor for the Determination of Tobramycin in Milk by Differential Pulse Voltammetry (DPV)

Abstract

A target-induced strand displacement (TISD) electrochemical aptasensor is reported for the sensitive determination of tobramycin (TOB). A novel substrate was synthesized by loading cerium-based metal organic framework (Ce-MOF) that was modified by Pd nanoparticles (PdNPs), onto polyethyleneimine (PEI)-modified molybdenum disulfide (MoS₂). The substrate (denoted by PEI-MoS₂/Ce-MOF@PdNPs) was used to modify the Au electrode (AuE) to expand the electrode surface area for subsequent cDNA loading. Gold-platinum core–shell particles (Au@Pt) loaded with aptamers (Apt) were introduced as signal tags and mimetic peroxidase to hybridize with cDNA and form a double-stranded structure. When the target was present, strand displacement dominated by TISD occurred and the signal tag was released from the electrode surface, turning the signal off. Using the optimal conditions, the linear range of the sensor was from 5 × 10⁻¹¹ to 1 × 10⁻⁶mol/L and the detection limit was 1.05 × 10⁻¹²mol/L with good stability, reproducibility, and specificity. The aptasensor provided good performance for the determination of tobramycin in milk.

KEYWORDS:

• electrochemical aptasensor
• milk analysis
• differential pulse voltammetry (DPV)
• polyethyleneimine-molybdenum disulfide/Ce-based metal organic framework@ Pd nanoparticles (PEI-MoS2/Ce-MOF@PdNPs)
• target-induced strand displacement (TISD)
• tobramycin

Disclosure statement

There are no conflicts of interest to declare.

Scheme 1. Schematic of electrochemical aptamer sensor for the determination of tobramycin. AA: ascorbic acid; BSA: albumin; TOB: tobramycin; DPV: differential pulse voltammetry.

Additional information

Funding

This work was financially supported by the National Natural Science Foundation of China (U1704126 and 41003046), Science and Technology Project of Henan Province, China (212102310072 and 162102210042), Plan for Scientific Innovation Talent of Henan University of Technology (2018RCJH13), and Innovative Funds Plan of Henan University of Technology (2020ZKCJ30).