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Gold (Au) and glassy carbon electrodes have been decorated with gold nanodendrites (NDs) using galvanic replacement reactions. Modification of the ND surfaces by lipoic acid N-hydroxysuccinimide ester allows to immobilise selenate reductase to the electrode surface, rendering it selective for the catalytic reduction of selenate (Se[O.sup.2-.sub.4], Se(VI)) to selenite (Se[O.sup.2-.sub.3], Se(IV)). Electrode modifications have been characterized by electrochemical impedance spectroscopy and cyclic voltammetry (CV). For selenate detection, CV and differential pulse voltammetry measurements have been carried out in 2-[4-(2-hydroxyethyl)piperazin-1-yl]ethanesulfonic acid buffer with pH 6.0. Under optimum conditions, the linear range for Au electrodes decorated with AuNDs was 0.3-203 [micro]g/L Se with a limit of detection of 0.01 [micro]g/L Se, which is a 274-fold improvement over using non-nanostructured surfaces for selenate detection. Other anions such as S[O.sup.2-.sub.4], N[O.sup.-.sub.3], N[O.sup.-.sub.2], P[O.sup.3-.sub.4], As[O.sup.3-.sub.4], and Se[O.sup.2-.sub.3] did not interfere with the detection of selenate. The electrochemical sensor was used for the detection of selenate in three different real samples with recovery between 98.5% and 102.0%. Key words: enzymatic biosensor, selenium reductase, selenate, nanodendrites, gold, 1. Introduction Metal nanoparticles have a variety of structural morphologies, including nanoplates, nanorods, nanodendrites, nanocages, nanoprisms, and nanostars. (1,2) Among them, nanodendrites are particularly attractive due to their distinctive hyperbranched [...]

This laboratory experiment introduces the fundamentals of electrochemical techniques to the undergraduate students by developing a simple and cost-effective miniaturized electrochemical setup for detecting UV-induced DNA damage. This is an imperative experiment, as it provides students first-hand experience with electrochemical techniques while reinforcing lecture material on the biosensing applications. In this experiment, a simple and daily use material such as an ordinary pencil lead acts as a platform for an electrochemical DNA sensor. A three-electrode cell setup is utilized to monitor UV-induced DNA damage. Students will test the hypothesis about UV-induced DNA damage by measuring the redox signal of guanine under various experimental conditions. The simple, fast, and inexpensive setup allows students to examine the factors that would influence the electrochemical signals. This experimental work provides an opportunity for students to learn how to design a simple electrochemical experiment for research purposes as well as handling the biological samples. Proposing a hypothesis and testing it by designing an experiment are the experiences that will be gained by the students while learning about the optimization and validation of an analytical technique.

The electrochemical reduction of CO2 (eCO2RR) holds promise in mitigating atmospheric greenhouse gas levels but is hindered by low reaction kinetics, high energy barriers, and poor selectivity. To address these challenges, we developed a novel series of cost‐effective AgCu‐containing metal‐aerogel catalysts with high electrochemical surface areas (ECSA) using a top‐down reduction approach. The Ag85Cu15 aerogel, with an ECSA of 27.41 cm2, achieved a Faraday efficiency (FE%) of 89.3 % for CO production at −0.9 V vs. RHE. Increasing the Cu content to over 50 % in the aerogel matrix produced small amounts of C2H4, with a maximum FE% of 12.9 % at −1.0 V vs. RHE. To further enhance CO2 reduction efficiency, multi‐walled carbon nanotubes (CNT) were incorporated into the Ag85Cu15 alloy aerogel via a hydrothermal treatment. The highly dispersed CNTs within the aerogel matrix increased the ECSA to 57.00 cm2 by forming a well‐defined porous structure through van‐der Waals interactions, improving CO selectivity, and achieving a FE% of 98.6 % at −0.7 V vs. RHE and a partial current density of 9.6 mA/cm2 in an H‐cell. 86 % of the initial FECO% was maintained during an 18 h test with continuous electrolysis. [ABSTRACT FROM AUTHOR]

The sensitive detection of ammonia at room temperature is crucial for both the chemical industry and human health. In this study, phosphorized NiMo layered double hydroxide (NiMo-P)-modified MXene-based composite materials were prepared using a combination of hydrothermal and calcination processes. A two-dimensional (2D)/2D van der Waals heterojunction formed between the MXene and NiMo-P phases facilitated the interlayer shuttling of charge carriers during gas adsorption. Furthermore, the composite material acquired abundant acidic sites during phosphorization, which fundamentally enhanced its NH3 sensing performance. In addition, the morphology of the composite was effectively controlled by tuning the poly-(methyl methacrylate). The hollow microspherical MXene@NiMo-P (MX-s@NiMo-P) composite material demonstrates highest sensing response to NH3. At 25 °C and 45% relative humidity (RH), the response of MX-s@NiMo-P to 100 ppm of NH3 was as high as 188.9%. After 30 d, the gas-sensing performance of the MX-s@NiMo-P sensor reached 93.4% of the initial value, highlighting its long-term stability over the 30-d period. This study describes an effective approach to improve the response of MXene-based gas sensor with long-term stability. [ABSTRACT FROM AUTHOR]

Naringenin (NRG), a flavanone compound present in citrus fruits, has a variety of beneficial physiological active functions such as antioxidant, anti-inflammatory, and hypoglycaemic. In this study, an sensor was constructed by electrodeposition and used for the electrochemical study of NRG. Reduced graphene oxide (rGO) and glutathione (GSH) showed the ability to synergistically amplify NRG signals and possessed good linearity in the concentration range of 10.00–1200.00 μ mol l−1. The linear equation is Ip = 0.0776logc + 0.9353 (R2 = 0.9901), and the limit of detection is 3.33 μ mol l−1. The sensor performed well in terms of reproducibility, stability, and selectivity, which in turn enabled the detection of NRG in tomatoes. The average recovery of the sensor is 95.68% to 111.92%, with RSD less than 11.89%. The results were also verified by Ultraviolet–visible spectroscopy(UV-vis). Furthermore, density-functional theory was employed to analyse the front track of the NRG, speculating that the NRG underwent a transfer of two electrons and two protons. [ABSTRACT FROM AUTHOR]

Stimuli-responsive peptide gels are a growing class of functional biomaterials that are involved in many applications in research. Here, we present a novel di-peptide hydrogel from the compound Boc--Phe--Trp--OH in various buffer and pH conditions. We examine the effects of different stimuli, including temperature and pH, on the mechanical strength of the gels through frequency rheology studies. We found that this hydrogelator is highly pH dependent, only forming a gel in a narrow range of pH 6-7. This hydrogelator hold promise for the development of new stimuli-responsive biomaterials for specific applications that require this type of specific stimuli. Key words: hydrogel, peptides, stimuli responsive, pH-dependent gelation, rheology. Les gels peptidiques stimulables constituent une classe grandissante de biomateriaux fonctionnels mis a contribution dans de nombreuses applications en recherche. Dans le present article, nous faisons etat d'un nouvel hydrogel dipeptidique produit a partir du compose Boc--Phe--Trp--OH dans divers tampons et conditions de pH. Nous examinons les effets de differents stimuli, tels que la temperature et le pH, sur la resistance mecanique des gels au moyen d'etudes de rheologie frequentielle. Nos resultats ont montre que ce gelifiant est tres sensible au pH, formant un hydrogel dans un intervalle de pH etroit (pH 6-7). Ce gelifiant constitue une avenue prometteuse pour la mise au point de nouveaux biomateriaux stimulables destines a des applications particulieres necessitant ce type de stimuli tres precis. [Traduit par la Redaction] Mots-cles : hydrogel, peptides, stimulable, gelification sensible au pH, rheologie., Introduction Peptide-based supramolecular gels are functional materials that have been the subject of research due to their versatility and their wide range of applications in many fields. (1) They can [...]