A theoretical and experimental study of polyaniline/GCE and DNA G-quadruplex conformation as an impedimetric biosensor for the determination of potassium ions

Nanomaterial-modified electrochemical aptasensors for tetracycline detection: a review

Excessive residues of tetracyclines in the livestock, food products and environment can lead to their accumulation in the human body through the food chain, unavoidably posing a threat to the human health. Therefore, it is essential to establish detection methods with high specificity, stability, and sensitivity. Among the numerous detecting techniques, electrochemical sensors with aptamers working as biorecognition elements have been increasingly applied to monitor tetracyclines. Notably, the synergy of a wide range of nanomaterials with aptamer-based sensors has improved the charge transfer efficiency and signal sensitivity. In this review, the advantages of aptamer-based recognition methods are discussed, and the measuring processes of electrochemical detection are introduced. Then, advances in electrochemical aptasensors used for detecting tetracyclines are summarized with an emphasis on the role of nanomaterials, such as carbon-based nanomaterials and gold-based nanomaterials, functioning as -transducing media and electrically conductive polymers. Finally, the current challenges and emerging trends in this field are also discussed, shedding light on the prospects for developing new aptasensors for tetracycline detection.

Recent advances in aptamer-based biosensors for potassium detection

Maintaining a stable level of potassium is crucial for proper bodily function because even a slight imbalance can result in serious disorders like hyperkalemia and hypokalemia. Therefore, detecting and monitoring potassium ion (K+) levels are of utmost importance. Various biosensors have been developed for rapid K+ detection, with aptamer-based biosensors garnering significant attention due to their high sensitivity and specificity. This review focuses on aptamer-based biosensors for K+ detection, providing an overview of their signal generation strategies, including electrochemical, field-effect transistor, nanopore, colorimetric, and fluorescent systems. The analytical performance of these biosensors is evaluated comprehensively. In addition, factors that affect their efficiency, such as their physicochemical properties, regeneration for reusability, and linkers/spacers, are listed. Lastly, this review examines the major challenges faced by aptamer-based biosensors in K+ detection and discusses potential future developments.

Voltammetric Sensor for Doxorubicin Determination Based on Self-Assembled DNA-Polyphenothiazine Composite

A novel voltammetric sensor based on a self-assembled composite formed by native DNA and electropolymerized N-phenyl-3-(phenylimino)-3H-phenothiazin-7-amine has been developed and applied for sensitive determination of doxorubicin, an anthracycline drug applied for cancer therapy. For this purpose, a monomeric phenothiazine derivative has been deposited on the glassy carbon electrode from the 0.4 M H2SO4-acetone mixture (1:1 v/v) by multiple potential cycling. The DNA aliquot was either on the electrode modified with electropolymerized film or added to the reaction medium prior to electropolymerization. The DNA entrapment and its influence on the redox behavior of the underlying layer were studied by scanning electron microscopy and electrochemical impedance spectroscopy. The DNA-doxorubicin interactions affected the charge distribution in the surface layer and, hence, altered the redox equilibrium of the polyphenothiazine coating. The voltametric signal was successfully applied for the determination of doxorubicin in the concentration range from 10 pM to 0.2 mM (limit of detection 5 pM). The DNA sensor was tested on spiked artificial plasma samples and two commercial medications (recovery of 90-95%). After further testing on real clinical samples, the electrochemical DNA sensor developed can find application in monitoring drug release and screening new antitumor drugs able to intercalate DNA.

H-CoNiSe2/NC dodecahedral hollow structures for high-performance supercapacitors

The synergistic effect between metal ions and increasing the surface area leads to the fabrication of supercapacitor materials with high capacities. It is predicted that transition metal selenide compounds will be ideal electrode materials for supercapacitors. However, the defects of poor conductivity and volume expansion of the compounds are fundamental problems that must be solved. In this work, we successfully synthesized the cobalt-nickel selenide nitrogen-doped carbon (H-CoNiSe₂/NC) hollow polyhedral composite structure using ZIF-67 as a precursor. The CoSe₂ and NiSe₂ nanoparticles embedded in the NC polyhedral framework offer a wealth of active sites for the whole electrode. Moreover, the presence of the NC structure in the proposed composite can simultaneously lead to improved conductivity and reduce the volume effect created during the cycling procedure. The H-CoNiSe₂/NC electrode provides high specific capacity (1131 C/g at 1.0 A/g) and outstanding cyclic stability (90.2% retention after 6000 cycles). In addition, the H-CoNiSe₂/NC//AC hybrid supercapacitor delivers ultrahigh energy density and power density (81.9 Wh/kg at 900 W/kg) and excellent cyclic stability (92.1% of the initial capacitance after 6000 cycles). This study will provide a supercapacitor electrode material with a high specific capacity for energy storage devices.Please confirm the corresponding affiliation for the 'Ali A. Ensafi' author is correctly identified.Error during converting author query response. Please check the eproofing link or feedback pdf for details.

Using the extract of pomegranate peel as a natural indicator for colorimetric detection and simultaneous determination of Fe3+ and Fe2+ by partial least squares–artificial neural network

A simple, novel, biocompatible, and sensitive spectrophotometric method was developed for colorimetric detection and speciation of Fe3+ and Fe2+ ions. The method is based on the complex formation of Fe3+ and Fe2+ with organic constituents containing functional groups in pomegranate peel extract (PG). Developing of the color is specifically established in the presence of Fe3+ and Fe2+. Accordingly, in addition to direct detection of both cations, we carried out a quantitative multivariate model for their accurate determination in real matrix aqueous samples. Due to spectral interference, the simultaneous determination of Fe3+ and Fe2+ mixtures using spectrophotometry is a problematic issue. A combined multivariate as partial least squares (PLS)–artificial neural network (ANN) was used to create and adjust a model and predict said cations in test and real sample sets. In this context, the calibration model is based on absorption spectra in the 400–900 nm range for 98 different mixtures of Fe3+ and Fe2+. Calibration matrices contained 1–12 and 1–10 μg ml−1 of Fe3+ and Fe2+, respectively. The detection limits for Fe3+ and Fe2+ were 0.53 and 0.14 μg ml−1, respectively. The root mean square error of prediction (RMSEP) for Fe3+ and Fe2+ with PLS‐ANN was 0.78, 1.65 and 1.062, 0.894 in Kalugan waterfall and Tehran tap water. This strategy can simultaneously determine Fe3+ and Fe2+ in real matrix samples, and the reliability of the determination is acceptable.

H2O2-activated in situ polymerization of aniline derivative in hydrogel for real-time monitoring and inhibition of wound bacterial infection

Wound is highly susceptible to bacterial infection, which can cause chronic wound and serial complications. However, timely treatment is hampered by the lack of real-time monitoring of wound status and effective therapeutic systems. Herein, in situ biosynthesis of functional conjugated polymer in artificial hydrogel was developed via the utilization of biological microenvironment to realize monitoring in real time of wound infection and inhibition of bacteria for the first time. Specially, an easily polymerizable aniline dimer derivative (N-(3-sulfopropyl) p-aminodiphenylamine, SPA) was artfully in situ polymerized into polySPA (PSPA) in calcium alginate hydrogel, which was initiated via the catalysis of hydrogen peroxide (H₂O₂) overexpressed in infected wound to produce hydroxyl radical (•OH) by preloaded horseradish peroxidase (HRP). Benefitting from outstanding near infrared (NIR) absorption of PSPA, such polymerization can be ingeniously used for real-time monitoring of H₂O₂ via naked-eye and photoacoustic signal, as well as NIR light-mediated photothermal inhibition of bacteria. Furthermore, combining the persistent chemodynamic activity of •OH, the in vivo experimental data proved that the wound healing rate was 99.03% on the 11th day after treatment. Therefore, the present work opens the way to manipulate in situ biosynthesis of functional conjugated polymer in artificial hydrogels for overcoming the issues on wound theranostics.

Point-of-care and self-testing for potassium: recent advances

Potassium is an important bodily electrolyte which is kept within tight limits in health. Many medical conditions as well as commonly-used drugs either raise or lower blood potassium levels, which can be dangerous or even fatal. For at-risk patients, frequent monitoring of potassium can improve safety and lifestyle, but conventional venous blood draws are inconvenient, don't provide a timely result and may be inaccurate. This review summarises current solutions and recent developments in point-of-care and self-testing potassium measurement technologies, which include devices for measurement of potassium in venous blood, devices for home blood collection and remote measurement, devices for rapid home measurement of potassium, wearable sensors for potassium in interstitial fluid, in sweat, in urine, as well as non-invasive potassium detection. We discuss the practical and clinical applicability of these technologies and provide future outlooks.