A ratiometric electrochemical sensor based on Cu-coordinated molecularly imprinted polymer and porous carbon supported Ag nanoparticles for highly sensitive and selective detection of perphenazine

A novel ratiometric electrochemical sensor based on dual-monomer molecularly imprinted polymer and Pt/Co3O4 for sensitive detection of chlorpromazine hydrochloride

Curcumin-based ratiometric electrochemical sensing interface for the detection of Cd2+ and Pb2+ in grain products

A ratiometric electrochemical sensor for the determination of exosomal glycoproteins

Given the significance of food safety, it is highly urgent to develop a sensitive yet reliable sensor for the practical analysis of algal toxins. As most of the developed sensors are disturbed by interfering substances and the target toxin is detected in a single-signal manner based on the immunoassay technology. Herein, we developed an aptamer-based dual-signal ratiometric electrochemical sensor for the sensitive and accurate analysis of microcystin-LR (MC-LR), using it as a proof-of-concept analyte. Methylene blue-tagged ssDNA (MB-ssDNA) was immobilized at the gold electrode surface accompanied with the absence of ferrocene-tagged ssDNA (Fc-ssDNA), resulting in a high differential pulse voltammetry (DPV) current of MB and a low DPV current of Fc. The recognition of MB-ssDNA by MC-LR stimulated the formation of MC-LR@MB-ssDNA, which induced the removal of MB-ssDNA from the electrode and the exposure of SH-ssDNA, enabling Fc-ssDNA to be captured at the electrode surface via nucleic acid hybridization. In comparison with MC-LR deficiency, the DPV signal of MB dropped along with an improved DPV signal of Fc, contributing to the ratiometric detection of MC-LR, with the limit of detection down to 0.0015 nM. Furthermore, this ratiometric electrochemical sensor was successfully explored to assess the bioaccumulated amount of MC-LR in the liver and meat of fish. The aptamer-based ratiometric strategy to develop an electrochemical MC-LR assay will offer a promising avenue to develop high-performance sensors, and the sensor will find more useful application in MC-LR-related aquatic product safety studies.

A ratiometric electrochemical sensor for bisphenol A detection based on Ag@Fe3O4-rGO composite

Determination of sertraline in pharmaceutical and biological samples using 1, 10-phenanthroline-terbium probe and silver nanoparticles enhanced fluorescence

A highly sensitive and selective electrochemical sensor based on computer-aided design of molecularly imprinted polymer for the determination of leflunomide

Simple self-referenced ratiometric electrochemical sensor for dopamine detection using electrochemically pretreated glassy carbon electrode modified by acid-treated multiwalled carbon nanotube

A ratiometric electrochemical sensor for dopamine detection based on hierarchical manganese dioxide nanoflower/multiwalled carbon nanotube nanocomposite modified glassy carbon electrode

Molecularly imprinted polymer-decorated signal on-off ratiometric electrochemical sensor for selective and robust dopamine detection

A portable smartphone-compatible ratiometric electrochemical sensor with ultrahigh sensitivity for anticancer drug mitoxantrone sensing

A novel ratiometric electrochemical sensor based on AuNPs decorated MIL-101(Fe) for simultaneously monitoring typical EDCs in milk

Ascorbic acid (AA) determination is of high importance in the diagnosis and treatment of diseases. Herein, we report a new ratiometric electrochemical sensor for ascorbic acid using a glassy carbon electrode (GCE) modified with a copper nanoparticle@resin nanosphere nanocomposite (CuNPs@RNS). The ratiometric strategy was established by immobilizing an internal reference (thionine) on the modified electrode using cyclic voltammetry (CV). The performance of the modified electrodes as well as the newly established ratiometric strategy was explored. The sensing platform had good electrocatalytic ability, reproducibility, and stability. In addition, the ratiometric strategy significantly improved the performance of electrochemical sensing with a wide linear range (0.0837 to 15.5 μM) and a low detection limit of 0.0279 μM under the optimal conditions. The original ratiometric electrochemical sensor was successfully applied to monitor ascorbic acid in tablets and urine. These results showed that the sensor provides a new strategy and broad prospects for biomolecular sensing with reliability and high sensitivity.

The major purpose of this work is to fabricate electrochemical glucose sensor by employing three electrodes of polydopamine (PDA), PDA-Ag nanoparticles (NPs) and PDA-Ag-CuO nanocomposites. Ag NPs were prepared using PDA as a reducing and stabilizing agent. The fabricated electrodes were evaluated in a phosphate buffer solution working as the electrolyte, spiked with varying concentrations of glucose ranged from 4 to 40 mM using cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). It was noted that Ag NPs and CuO NPs have face centered cubic and orthorhombic structures, respectively. Morphological studies displayed cauliflower shape for PDA, nanoluster spheres for Ag NPs and nanoneedles for CuO NPs ranged from 10 to 35 nm and 30 to 70 nm, respectively. The PDA-Ag NPs nanocomposite electrode exhibited a sensitivity of 1.0 × 10 −5 A·mM −1 , a correlation coefficient (R 2 ) of 96.5%, a limit of detection (LOD) of 1.73 mM, and a limit of quantification (LOQ) of 5.77 mM. It also demonstrated a relative standard deviation (RSD) of less than 1.5% and a repeatability of 1.6 × 10 −5 .PDA-Ag-CuO nanocomposite electrode achieved a sensitivity of 9.0 × 10 −6 A·mM −1 , with a strong linearity (R 2 = 99.2%), a calculated detection limit (LOD) of 1.08 mM, and a quantification limit (LOQ) of 3.60 mM. The relative standard deviation (RSD) was calculated to be below 3%, with a repeatability value of 2.8 × 10 −5 . The interference with glucose by ascorbic acid, urea, cholic acid, and dopamine was assessed, and the results indicated that PDA-Ag NPs-CuO nanocomposite electrode has a high selectivity to glucose.

The in vivo monitoring of ascorbic acid (AA) following physiological and pathological events is of great importance because AA plays a critical role in brain functions. The conventional electrochemical sensors (ECSs) usually suffered from poor selectivity and sluggish electron transfer kinetics for cerebral AA oxidation. The exploitation of ECSs adapt to the electrochemical detection (ECD)-microdialysis system, here we reported a facile ratiometric electrochemical sensor (RECS) for in vivo/online repetitive measurements of cerebral AA in brain microdiaysate. The sensor were constructed by careful electrodeposition of graphene oxide (GO) onto glassy carbon (GC) electrodes. Methylene blue (MB) was electrostatically adsorbed onto the GO surface as a built-in reference to achieve ratiometric detection of AA. The subsequent proper electroreduction treatment was able to readily facilitate the oxidation of AA at a relatively negative potential (-100 mV) and the oxidation of MB at separated potential (-428 mV). The in vitro experiments demonstrated that the RECS exhibited high sensitivity (detection limit: 10 nM), selectivity, and stability toward AA determination, enabling the in vivo/online repetitive measurement of cerebral AA in brain microdiaysate with high reliability. As a result, the designed RECS was successfully applied in the ECD-microdialysis system to in vivo/online repetitive monitoring the dynamic change of cerebral AA in the progress of the global cerebral ischemia/reperfusion events. More, the microinjection of endogenous AA and AA oxidase (AAOx) verified the reliability of the proposed RECS for in vivo/online repetitive cerebral AA detection. This proposed sensor filled the gap that no rational electrochemical sensor has been developed for the ECD-microdialysis system since its creation by the Mao group in 2005, which provided a reliable and effective method for brain chemistry research.