Silver nanoparticles conjugated MnFe-based Prussian blue analogue for voltammetric and impedimetric bioaptasensing of amifostine (ethyol)

A novel bioaptasensing-based electrochemical method for determination of amifostine (AMF) is proposed. The electrochemical aptasensor is based on modification of a glassy carbon electrode with a nanocomposite consisting of silver nanoparticles @ MnFe Prussian blue analogue nanospheres (AgNPs@MnFePBA NS), followed by immobilization of aptamer via Ag-N bonds (aptamer/AgNPs@MnFePBA NS/GCE). Experimental parameters including pH, incubation time, and aptamer concentrations were optimized. Electrochemical impedance spectroscopy (EIS) and differential pulse voltammetric (DPV) techniques were utilized to quantify AMF. The anodic peak current (∆Ipa) and charge transfer resistance (∆Rct) differences increase in the presence of AMF. Under the optimal conditions, using the redox probe, the electrochemical aptasensor exhibited linear ranges of 0.34-45 nmol L^-1 and 0.69-45 nmol L^-1 with LODs of 0.11 nmol L^-1 and 0.23 nmol L^-1 for EIS and DPV, respectively. The aptasensor was used to determine AMF in human plasma and in the presence of interfering species with recoveries and RSDs in the range 97.8-103.2% and 2.2-4.2%, respectively. Graphical abstract.

Colorimetric and Ratiometric Fluorescence Dual-Mode Sensing of Glucose Based on Carbon Quantum Dots and Potential UV/Fluorescence of o-Diaminobenzene

A novel colorimetric and ratiometric fluorescence sensor was constructed by using carbon quantum dots (CQDs) and o-diaminobenzene (ODB). Unlike ODB by itself, ODB oxide (oxODB) not only emits fluorescence, but also produces ultraviolet (UV) absorption. Therefore, on the basis of the potential optical properties of ODB, glucose oxidase (Gox) and horseradish peroxidase (HRP) were introduced into a CQDs⁻ODB system for the quantitative oxidation of ODB. When glucose is present, it is oxidized by oxygen under the catalytic action of its oxidase to form hydrogen peroxide. Hydrogen peroxide is a strong oxidant that can rapidly oxidize ODB through the catalysis of horseradish peroxidase. oxODB can cause changes in the fluorescence ratio (I550/I446) and absorbance ratio (A/A₀). At the same time, the color of the detection solution can also change under sunlight and ultraviolet lamps. Therefore, glucose can be quantitatively detected by ratiometric fluorescence and colorimetry simultaneously, and semi-quantitatively detected by observing the colors with sunlight and ultraviolet lamps of 365 nm. This increases not only the convenience but also the accuracy of detection. In addition, this sensor has good selectivity and can be used for the determination of glucose in serum, providing a new idea for the development of blood glucose sensors.