Ultrasensitive Controlled Release Aptasensor Using Thymine–Hg²⁺–Thymine Mismatch as a Molecular Switch for Hg²⁺ Detection

Abstract

An ultrasensitive controlled release system electrochemical aptasensor (CRSEA) has been developed for supersensitive determination of mercury ions (Hg 2+ ), using gold nanoparticle-linked specific single-stranded DNA (Au NPs-ssDNA) as a molecular gate and mesoporous silica nanocontainers (MSNs) as containers. MSNs have a rich porous structure, thus entrapping the toluidine blue (TB) molecules inside. It is worth noting that Hg 2+ binds to the ssDNA with multiple thymine (T) and induces the ssDNA to form a hairpin structure, which makes the separation of the Au NPs-ssDNA from the MSNs. Eventually, the stored TB molecules were released from MSNs. The electron transfer signals of TB were detected stably by a differential pulse voltammetry (DPV) detection method, which are correlated with the concentration of Hg 2+ . Therefore, the wide linear range (10 pM−100 μM) and low limit of detection (2.9 pM) were obtained, and the system also displayed an apparent electrochemical signal response in real sample detection and showed a promising possibility in actual monitoring.

A ratiometric electrochemical strategy based on Fe (iii) and Pt (iv) for immobilization-free detection of Escherichia coli

“…The Au NPs and tDNA/Au NPs were prepared according to the reported work (the synthesis process of Au NPs is given in the ESI†). 36,37 After Au NPs were synthesized, 5 μL TCEP (1 mol L −1 ) was added to 100 μL tDNA (10 μmol L −1 ) and reduced at room temperature for 30 min. After that, 1 mL of the prepared Au NPs solution was added to the mixture and cultured for 24 h, and then stored at 4 °C for later use.…”

“…S1C, † the absorption peak at 260 nm corresponds to the characteristic absorption peak of aptamer DNA. 37 In addition; the magnetic properties of composites were assayed by VSM and Fig. S1D † presents the VSM analysis and the magnetic hysteresis loops related to CuFe 2 O 4 , CuFe 2 O 4 /GO and PANI/CuFe 2 O 4 / GO composites.…”

Tetrahedral DNA-directed core-satellite assembly as SERS sensor for mercury ions at the single-particle level

“…According to previous reports, it is well-known that Hg 2+ ions induce the conjunction of the thymine-thymine (T-T) base pair. 31,32 The thorough principle for Hg 2+ detection is described in Scheme 1. Upon binding the target Hg 2+ , the Hg 2+ aptamer is converted to a hairpin structure owing to the formation of the T-Hg 2+ -T bond, which induces the transformation of the tetrahedra from a relaxed state to a taut state.…”

Electrochemistry/Photoelectrochemistry-Based Immunosensing and Aptasensing of Carcinoembryonic Antigen

“…Until now, since aptamers have the features of low immunogenicity, excellent programmability, and easy chemical modification, the focus has been on their sensing applications in clinical diagnosis, food security, and environmental monitoring [116][117][118]. Photoelectrochemical aptasensors, an emerging and interesting research subject, also make a significant contribution to the monitoring of tumor markers because of their selectivity, stability, and potential for miniaturization and portability [119,120].…”