Comparison of two fabricated aptasensors based on modified carbon paste/oleic acid and magnetic bar carbon paste/Fe3O4@oleic acid nanoparticle electrodes for tetracycline detection

Aptamer-Based Biosensors for Antibiotic Detection: A Review

Antibiotic resistance and, accordingly, their pollution because of uncontrolled usage has emerged as a serious problem in recent years. Hence, there is an increased demand to develop robust, easy, and sensitive methods for rapid evaluation of antibiotics and their residues. Among different analytical methods, the aptamer-based biosensors (aptasensors) have attracted considerable attention because of good selectivity, specificity, and sensitivity. This review gives an overview about recently-developed aptasensors for antibiotic detection. The use of various aptamer assays to determine different groups of antibiotics, like β-lactams, aminoglycosides, anthracyclines, chloramphenicol, (fluoro)quinolones, lincosamide, tetracyclines, and sulfonamides are presented in this paper.

Electrochemical detection of urinary microRNAs via sulfonamide-bound antisense hybridisation

Altered serum and plasma microRNA (miRNA) expression profiles have been observed in numerous human diseases, with a number of studies describing circulating miRNA biomarkers for cancer diagnosis, prognosis and response to treatment, and recruitment to clinical trials for miRNA-based drug therapy already underway. Electrochemical detection of biomarkers in urine has several significant advantages over circulating biomarker analysis including safety, cost, speed and ease of conversion to the point of care environment. Consequently, much current research is underway to identify urinary miRNA biomarkers for a variety of pathologies including prostate and bladder malignancies, and renal disorders. We describe here a robust method capable of electrochemical detection of human urinary miRNAs at femtomolar concentrations using a complementary DNA-modified glassy carbon electrode. A miR-21-specific DNA hybridisation probe was immobilised onto a glassy carbon electrode modified by sulfonic acid deposition and subsequent chlorination. In our pilot system, the presence of synthetic mature miR-21 oligonucleotides increased resistance at the probe surface to electron transfer from the ferricyanide/ferrocyanide electrolyte. Response was linear for 10 nM-10 fM miR-21, with a limit of detection of 20 fM, and detection discriminated between miR-21, three point-mutated miR-21 sequences, and miR-16. We then demonstrated similar sensitivity and reproducibility of miR-21 detection in urine samples from 5 human control subjects. Our protocol provides a platform for future high-throughput screening of miRNA biomarkers in liquid biopsies.

Instrument-free visual detection of tetracycline on an autocatalytic DNA machine using a caged G-quadruplex as the signal reporter

An instrument-free visual biosensor for the amplified detection of tetracycline has been successfully constructed using an autocatalytic DNA machine as the signal amplifier and a caged G-quadruplex as the signal reporter. The assay is ultrasensitive, enabling the visual detection of trace levels of tetracycline as low as 1 pM without instrumentation.

Magnetic Nanoparticles for Antibiotics Detection

Widespread use of antibiotics has led to pollution of waterways, potentially creating resistance among freshwater bacterial communities. Microorganisms resistant to commonly prescribed antibiotics (superbug) have dramatically increased over the last decades. The presence of antibiotics in waters, in food and beverages in both their un-metabolized and metabolized forms are of interest for humans. This is due to daily exposure in small quantities, that, when accumulated, could lead to development of drug resistance to antibiotics, or multiply the risk of allergic reaction. Conventional analytical methods used to quantify antibiotics are relatively expensive and generally require long analysis time associated with the difficulties to perform field analyses. In this context, electrochemical and optical based sensing devices are of interest, offering great potentials for a broad range of analytical applications. This review will focus on the application of magnetic nanoparticles in the design of different analytical methods, mainly sensors, used for the detection of antibiotics in different matrices (human fluids, the environmental, food and beverages samples).

Developing an electrochemical sensor based on a carbon paste electrode modified with nano-composite of reduced graphene oxide and CuFe2O4 nanoparticles for determination of hydrogen peroxide

In this paper, a highly sensitive voltammetric sensor based on a carbon paste electrode with CuFe₂O₄ nanoparticle (RGO/CuFe₂O₄/CPE) was designed for determination of hydrogen peroxide (H₂O₂). The electrocatalytic reduction of H₂O₂ was examined using various techniques such as cyclic voltammetry (CV), chronoamperometry, amperometry and differential pulse voltammetry (DPV). CuFe₂O₄ nanoparticles were synthesized by co-precipitation method and characterized with scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) techniques. Then, a high conductive platform based on a carbon paste electrode modified with RGO and CuFe₂O₄ nanoparticles was prepared as a suitable platform for determination of hydrogen peroxide. Under the optimum conditions (pH5), the modified electrode indicated a fast amperometric response of <2s, good linear range of 2 to 200μM, low detection limit of 0.52μM for determination of hydrogen peroxide. Also, the peak current of differential pulse voltammetry (DPV) of hydrogen peroxide is increased linearly with its concentration in the ranges of 2 to 10μM and 10 to 1000μM. The obtained detection limit for hydrogen peroxide was evaluated to be 0.064μM by DPV. The designed sensor was successfully applied for the assay of hydrogen peroxide in biological and pharmaceutical samples such as milk, green tea, and hair dye cream and mouthwash solution.

Design an aptasensor based on structure-switching aptamer on dendritic gold nanostructures/Fe3O4@SiO2/DABCO modified screen printed electrode for highly selective detection of epirubicin

The present work describes a label free electrochemical aptasensor for selective detection of epirubicin. In this project, 5'-thiole terminated aptamer was self-assembled on carbon screen printed electrode, which modified with electrodeposited gold nanoparticles on magnetic double-charged diazoniabicyclo [2.2.2] octane dichloride silica hybrid (Fe₃O₄@SiO₂/DABCO) by Au-S bond. The interactions of epirubicin with aptamer on the AuNPs/Fe₃O₄@SiO₂/DABCO/SPE have been studied by cyclic voltammetry, linear sweep voltammetry and electrochemical impedance spectroscopy. Under optimized conditions, the peak current of epirubicin increased linearly with increasing epirubicin concentration, due to the switching in the aptamer conformation and formation of aptamer- epirubicin complex instead of aptamer on the modified electrode surface. The Apt/AuNPs/Fe₃O₄@SiO₂/DABCO/SPE is sensitive, selective and has two linear range from 0.07µM to 1.0µM and 1.0µM to 21.0µM with a detection limit of 0.04µM. The applicability of the aptasensor was successfully assessed by determination of epirubicin in a human blood serum sample.