Amperometric determination of Myo-inositol using a glassy carbon electrode modified with nanostructured copper sulfide

Diffusive Memristor with CuS Nanoparticles Embedded in Polymeric Film as Artificial Nociceptor

The threshold behavior and the ion diffusion dynamics in diffusive volatile memristors have a very uncanny resemblance to the transduction process of biological nociceptors. Hence, the diffusive memristors are considered the most suited for making artificial nociceptive systems. To facilitate their widespread adoption, it is imperative to develop polymeric or organic-inorganic hybrid material-based diffusive memristors that are economical, biocompatible, and easily processable. In this study, we present a cluster-type polymeric diffusive memristor where copper is used as the active top electrode. The switching medium comprises copper(II) sulfide (CuS) nanoparticles embedded in poly(ethylene oxide) (PEO). The devices show electrochemical metalization (ECM)-type and bidirectional diffusive volatile memory with high nonlinearity (104) and turn-on slope (5.6 mV/dec). They reliably remain diffusive volatile with up to 10 wt % CuS in PEO and for a wide range of compliance (10-6 to 10-2 A) without transitioning to the bipolar nonvolatile type. The low reduction potential of CuS and optimal segmental dynamics of PEO work synergistically to ensure stable and reproducible diffusive memory. The CuS nanoparticles act as bipolar electrodes, undergoing local oxidation and reduction under the influence of the bias. The switching of resistance states in the CuS-PEO memristors is attributed to the formation of cluster-type filaments between CuS nanoparticles within the PEO matrix supported by the participation of copper ions from the top Cu electrode. The observation of low filament temperature and the independence of on-state resistance with respect to the device area and temperature further corroborate the cluster-type filament in CuS-PEO memristors. Using a 5 wt % CuS-based device, an artificial nociceptor is realized, which successfully mimics most of the nociceptive plasticities such as threshold, relaxation, no adaptation, and sensitization.

Exploring Label-Free Imaging Techniques with Copper Sulfide Microspheres for Observing Breast Cancer Cells

A single breast cancer is a prevalent form of cancer, affecting over 2.3 million women worldwide, as reported by the World Health Organization. Recently, researchers have extensively explored the utilization of biomaterials in breast cancer theranostics. One notable biomaterial being investigated is various structures of copper sulfide (CuS). In this work, a microsphere (MS) structure composed of CuS was employed for label-free imaging of MCF-7 breast cancer cells and normal Vero cells, respectively. Various label-free imaging techniques, such as bright field, dark field, phase contrast (PC), and differential interference contrast (DIC), were employed to capture images of CuS MSs, cell, and intact CuS MSs within a cell. The study compared the outcomes of each imaging technique and determined that DIC imaging provided the highest resolution for cells incubated with CuS MSs. Furthermore, the combination of PC and DIC techniques proved to be effective for imaging breast cancer cells in conjunction with CuS MSs. This research underscores the potential of CuS MSs for label-free cell detection and emphasizes the significance of selecting appropriate imaging techniques to attain high-quality images in the field of cell observation.

Modulating nanostructures with polyvinylpyrrolidone: Design and development of a porous, biocompatible, and pH-Stable core-shell magnetic microrobot for demonstrating drug absorption from wastewater

Increased antineoplastic drug concentrations in wastewater stem from ineffective treatment plants and increased usage. Although microrobots are promising for pollutant removal, they face hurdles in developing a superstructure with superior adsorption capabilities, biocompatibility, porosity, and pH stability. This study focused on adjusting the PVP concentration from 0.05 to 0.375 mM during synthesis to create a favorable CMOC structure for drug absorption. Lower PVP concentrations (0.05 mM) yielded a three-dimensional nanoflower structure of CaMoO4 and CuS nanostructures, whereas five-fold concentrations (0.25 mM) produced a porous structure with a dense CuS core encased in a transparent CaMoO4 shell. The magnetically movable and pH-stable COF@CMOC microrobot, achieved by attaching CMOC to cobalt ferrite (CoF) NPs, captured doxorubicin efficiently, with up to 57 % efficiency at 200 ng/mL concentration for 30 min, facilitated by electrostatic interaction, hydrogen bonding, and pore filling of DOX. The results demonstrated that DOX removal through magnetic motion showed superior performance, with an estimated improvement of 57% compared to stirring conditions (17 %). A prototype PDMS microchannel system was developed to study drug absorption and microrobot recovery. The CaMoO4 shell of the microrobots exhibited remarkable robustness, ensuring long-lasting functionality in harsh wastewater environments and improving biocompatibility while safeguarding the CuS core from degradation. Therefore, microrobots are a promising eco-friendly solution for drug extraction. These microrobots show promise for the selective removal of doxorubicin from contaminated wastewater.

Microwave-assisted synthesis of ZnS@CuInxSy for photocatalytic degradation of coloured and non-coloured pollutants

Copper indium sulfide (CuInS2) exhibits strong visible light absorption and thus has the potential for good photocatalytic activity; however, rapid charge recombination limits its practical usage. An intriguing strategy to overcome this issue is to couple CuInS2 with another semiconductor to form a heterojunction, which can improve the charge carrier separation and, hence, enhance the photocatalytic activity. In this study, photocatalysts comprising CuInS2 with a secondary CuS phase (termed CuInxSy) and CuInxSy loaded with ZnS (termed ZnS@CuInxSy) were synthesized via a microwave-assisted method. Structural and morphological characterization revealed that the ZnS@CuInxSy photocatalyst comprised tetragonal CuInS2 containing a secondary phase of hexagonal CuS, coupled with hexagonal ZnS. The effective band gap energy of CuInxSy was widened from 2.23 to 2.71 as the ZnS loading increased from 0 to 30%. The coupling of CuInxSy with ZnS leads to long-lived charge carriers and efficient visible-light harvesting properties, which in turn lead to a remarkably high activity for the photocatalytic degradation of brilliant green (95.6% in 5 h) and conversion of 4-nitrophenol to 4-nitrophenolate ions (95.4% in 5 h). The active species involved in these photocatalytic processes were evaluated using suitable trapping agents. Based on the obtained results, photocatalytic mechanisms are proposed that emphasize the importance of h+, O2•-, and OH- in photocatalytic processes using ZnS@CuInxSy.

Unraveling the antimicrobial activity of CuS functionalized titanates under visible LED light irradiation

Titanate nanotubes (TNs) functionalized with CuS nanoparticles using the microwave-assisted hydrothermal method were characterized via XRD, Raman spectroscopy, UV-Vis spectrophotometry, and N2 physisorption. The as-synthesized CuS/TNs had anatase as the main crystalline phase and the band-gap energy was in the visible region, 2.9 eV. The TNs were recrystallized on titania and functionalized with CuS, forming spherical bundles. SEM showed agglomerates of cauliflower-like semispherical particles. The antimicrobial photoactive assets were evaluated against the bacteria Staphylococcus aureus and Escherichia coli. Inhibition was clearly visible in S. aureus after the first 20 min of exposure to a 6-W LED irradiation lamp. The visible-light catalyzed completely and irreversibly the inactivation of S. aureus after 60 min, however, in the case of E. coli, this material only slightly disturbed its growth, which was recovered after 60 min. The successful result obtained with S. aureus can be explained by the fact that it lacks periplasmic superoxide dismutase (SOD) but has staphyloxanthin for external protection against ROS. However, the CuS/TN particles could release Cu2+ ions, which got attached to bacterium structures or entered the cytoplasm; these events together with the generation of ROS under visible LED light helped inactivate quickly staphyloxanthin, thus inflicting permanent damage to the periplasmic membrane.

A self-assembled three-dimensional hierarchical nanoflower: an efficient enzyme-mimetic material for cancer cell detection that improves ROS generation for therapy

Three-dimensional (3D) nanomaterials with high functional properties are emerging as the most promising artificial enzymes for overcoming the significant disadvantages of natural enzymes. Anticancer therapy using 3D-enzyme mimetic materials has emerged as an essential development for catalyzing cancer cell destruction. We report for the first time a novel 3D-based enzyme mimetic material, CaMoO4/MoS2/CuS nanoflower (CMC NF), that exhibits a large specific surface area, uniform flower-like structure, excellent biocompatibility, and high porosity, making it a suitable candidate for cancer detection and therapy. Additionally, CMC NFs were conjugated with folic acid (FA) to selectively target cancer cells, resulting in FA-CMC NFs explicitly binding to overexpressed folate receptor alpha (FRα) in MDA-MB-231 cells. Based on the peroxidase activity, the FA-CMC NFs are an effective nanoprobe for the selective detection of MDA-MB-231 cells over a wide detection range (50 to 5.5 × 104 cells per mL) with a low limit of detection (LOD) value of 10 cells per mL. In addition to their cancer detection capability, the FA-CMC NFs also effectively generated ˙OH radicals in a concentration-dependent manner to treat cancer cells. Under light conditions, the FA-CMC NFs with H2O2 solution showed efficient degradation of methylene blue (MB) dye, and the solution color appeared to fade within 15 min, indicating that they generated ˙OH radicals, which can efficiently kill cancer cells. Thus, the superior functionality of FA-CMC NFs offers cost-effective, facile, and reliable cancer cell detection, providing a new treatment option for cancer treatment and diagnosis.

Sodium Alginate-CuS Nanostructures Synthesized at the Gel-Liquid Interface: An Efficient Photocatalyst for Redox Reaction and Water Remediation

The use of visible light to propel chemical reactions is an exciting area of study that is crucial in the current socioeconomic environment. However, various photocatalysts have been developed to harness visible light, which consume high energy during synthesis. Thus, synthesizing photocatalysts at gel-liquid interfaces in ambient conditions is of scientific importance. Herein, we report an environmentally benign sodium alginate gel being used as a biopolymer template to synthesize copper sulfide (CuS) nanostructures at the gel-liquid interface. The driving force for the synthesis of CuS nanostructures is varied by changing the pH of the reaction medium (i.e., pH 7.4, 10, and 13) to tailor the morphology of CuS nanostructures. The CuS nanoflakes obtained at pH 7.4 transform into nanocubes when the pH is raised to 10, and the nanostructures deform at the pH of 13. Fourier transform infrared spectroscopy (FTIR) confirms all the characteristic stretching of sodium alginate, whereas the CuS nanostructures are crystallized in a hexagonal crystal system, as revealed by the powder X-ray diffraction analysis. The high-resolution X-ray photoelectron spectroscopy (XPS) spectra show the +2 and -2 oxidation states of copper (Cu) and sulfur (S) ions, respectively. The CuS nanoflakes physisorbed a higher concentration of greenhouse CO₂ gas. Owing to a lower band gap of CuS nanoflakes synthesized at a pH of 7.4, compared to other CuS nanostructures prepared at pH 10 and 13, CuS photocatalytically degrades 95% of crystal violet and 98% of methylene blue aqueous dye solutions in 60 and 90 min, respectively, under blue light illumination. Additionally, sodium alginate-copper sulfide (SA-CuS) nanostructures synthesized at a pH of 7.4 demonstrate excellent performance in photoredox reactions to convert ferricyanide to ferrocyanide. The current research opens the door to developing new photocatalytic pathways for a wide range of photochemical reactions involving nanoparticle-impregnated alginate composites prepared on gel interfaces.

Quantification of Myoinositol in Serum by Electrochemical Detection with an Unmodified Screen-Printed Carbon Electrode

Simple, rapid, and accurate detection of myoinositol (MI) concentration in blood is crucial in diagnosing polycystic ovary syndrome, neurological disorders, and cancer. A novel electrochemical detection (IED) method was established to quantify MI in human serum using a disposable unmodified screen-printed carbon electrode (SPCE) for the first time. MI was detected indirectly by the reaction product of myoinositol dehydrogenase (IDH) and cofactor β-nicotinamide adenine dinucleotide (NAD⁺). Good linear calibration curves were obtained at the concentration range from 5.0 μM to 500.0 μM (R ² = 0.9981) with the lower limits of detection (LOD) and quantification (LOQ) of 1.0 μM and 2.5 μM, respectively. Recoveries were calculated at three spiked concentrations, and the values were between 90.3 and 106%, with relative standard deviation values of 3.2-6.2% for intraday precision and 7.1-9.0% for interday precision. The SPCE-electrochemical biosensor is simple, accurate, and without modification, showing great potential for point-of-care testing (POCT) of serum MI in clinical samples.

Vitamins in wine: Which, what for, and how much?

Vitamins are essential compounds to yeasts, and notably in winemaking contexts. Vitamins are involved in numerous yeast metabolic pathways, including those of amino acids, fatty acids, and alcohols, which suggests their notable implication in fermentation courses, as well as in the development of aromatic compounds in wines. Although they are major components in the course of those microbial processes, their significance and impact have not been extensively studied in the context of winemaking and wine products, as most of the studies focusing on the subject in the past decades have relied on relatively insensitive and imprecise analytical methods. Therefore, this review provides an extensive overview of the current knowledge regarding the impacts of vitamins on grape must fermentations, wine-related yeast metabolisms, and requirements, as well as on the profile of wine sensory characteristics. We also highlight the methodologies and techniques developed over time to perform vitamin analysis in wines, and assess the importance of precisely defining the role played by vitamins in winemaking processes, to ensure finer control of the fermentation courses and product characteristics in a highly complex matrix.