Self-redox reaction driven in situ formation of Cu2O/Ti3C2Tx nanosheets boost the photocatalytic eradication of multi-drug resistant bacteria from infected wound.

BACKGROUND: MXenes with interesting optical and electrical properties have been attractive in biomedical applications such as antibacterial and anticancer agents, but their low photogeneration efficiency of reactive oxygen species (ROS) and poor stability are major concerns against microbial resistance. METHODS: Water-dispersible single layer Ti3C2Tx-based MXene through etching tightly stacked MAX phase precursor using a minimally intensive layer delamination method. After addition of Cu(II) ions, the adsorbed Cu(II) ions underwent self-redox reactions with the surface oxygenated moieties of MXene, leading to in situ formation of Cu2O species to yield Cu2O/Ti3C2Tx nanosheets (heterostructures). RESULTS: Under NIR irradiation, the Cu2O enhanced generation of electron-hole pairs, which boosted the photocatalytic production of superoxide and subsequent transformation into hydrogen peroxide. Broad-spectrum antimicrobial performance of Cu2O/Ti3C2Tx nanosheets with sharp edges is attributed to the direct contact-induced membrane disruption, localized photothermal therapy, and in situ generated cytotoxic free radicals. The minimum inhibitory concentration of Cu2O/Ti3C2Tx nanosheets reduced at least tenfold upon NIR laser irradiation compared to pristine Cu2O/Ti3C2Tx nanosheets. The Cu2O/Ti3C2Tx nanosheets were topically administrated on the methicillin-resistant Staphylococcus aureus (MRSA) infected wounds on diabetic mice. CONCLUSION: Upon NIR illumination, Cu2O/Ti3C2Tx nanosheets eradicated MRSA and their associated biofilm to promote wound healing. The Cu2O/Ti3C2Tx nanosheets with superior catalytic and photothermal properties have a great scope as an effective antimicrobial modality for the treatment of infected wounds.

Gold Nanoparticle Embedded on a Reduced Graphene Oxide/polypyrrole Nanocomposite: Voltammetric Sensing of Furazolidone and Flutamide.

A new electrochemical sensor has been constructed based on the in situ preparation of gold nanoparticle embedded on reduced graphene oxide and polypyrrole nanotube (AuNP@rGO/PPyNT) composite through a nanosecond laser-induced heating technique. The as-prepared composite is used for individual as well as the simultaneous electrochemical determination of chemotherapy drug (furazolidone, FU) and anticancer drug (flutamide, FLT). The composite was analyzed by X-ray Diffraction, scanning electron microscopy/energy-dispersive X-ray analysis, transmission electron microscopy, Raman spectrometry, and X-ray photoelectron spectroscopy analysis, thus confirming the successful synthesis of this composite and its physical features. The modified AuNP@rGO/PPyNT electrode was examined through cyclic voltammetry and differential pulse voltammetry (DPV) methods in pH 7.0 for the determination of FU and FLT in individual, simultaneous, and mixed systems. The fabricated sensor showed wide linear responses (0.01-1080.11 µM and 0.01-1214.11 µM) of analytes, with the lower limits of detection of 2.3 and 2.45 nM and higher sensitivity of 53.75 and 50.06 µA µM-1 cm-2, respectively. Furthermore, the constructed sensor demonstrates higher stability, reproducibility, and repeatability, and is effectively applied for the analysis of FU and FLT content in the human serum sample analysis with satisfactory recovery.

Voltammetric determination of vitamin B2 by using a highly porous carbon electrode modified with palladium-copper nanoparticles.

Palladium-copper nanoparticles were placed on activated carbon to give a nanocomposite for electrochemical sensing of riboflavin (vitamin B2). The activated carbon was produced by pyrolysis of natural waste of pistachio nutshells after KOH activation and under a nitrogen atmosphere. The carbons possess a large surface area and micro/meso-porosity. The nanocomposite was characterized by a variety of techniques to confirm structures and morphology. A screen-printed electrode modified with the composite was examined by EIS, CV, DPV, and amperometry. The effects of pH value, scan rate, and stability of the modified electrode were studied. Under optimized conditions, vitamin B2 displays a well-expressed oxidation peak at -0.15 V (vs. Ag/AgCl) in solutions with a pH value of 7.0. The voltammetric signal increases linearly in the 0.02 to 9 µM concentrations range and a lower detection limit of 7.6 pM. The sensor was successfully applied to the determination of vitamin B2 even in the presence of other common vitamins and in (spiked) raw milk samples. Graphical abstract A highly porous carbon was modified with palladium-copper alloy nanoparticles and used to coat an electrode for sensing of riboflavin (vitamin B2) by voltammetry.

Synthesis of novel Type-II MnNb2O6/g-C3N4 Mott-Schottky heterojunction photocatalyst: Excellent photocatalytic performance and degradation mechanism of fluoroquinolone-based antibiotics.

Fluoroquinolone antibiotics have been encountered in aquatic environments in quantities giving rise to significant concern recently. To cope with this problem, it is necessary to design a semiconductor photocatalyst having excellent photocatalytic efficiency to eliminate the antibiotics. The heterojunction is a likely situate where the efficiency of relevant photocatalyst can be strengthened. In this study, the performance of MnNb2O6/g-C3N4 (MNO/g-CN) composites in the photocatalytic degradation of ciprofloxacin (CIP) and tetracycline-HCl (TCH) antibiotics was explored. Enhanced photocatalytic activity of MNO/g-CN was found to be owing to electron's shifting between the MNO, and g-CN sheets, which promotes the formation of photo-generated e⁻/h⁺ pairs. This shows a low-waste, high-performance material exists to eradicate CIP and TCH from wastewater. Further, the structural, photochemical and light interacted properties of the MNO/g-CN photocatalyst, prepared by solvothermal method and sonication, were described using photochemical, physiochemical and electrochemical approaches. The synthesized photocatalyst owes its particular efficiency to its methodical photo-degradation of CIP and TC using visible light. The optimum composite 15% MNO/g-CN evinced the greatest photocatalytic efficiency with CIP and TCH photo-degradation of 94.10%, and 98.50%, respectively, and degradation mechanism were investigated using LC-MS spectroscopy. The suitable photocatalytic activity is ascribed to lower the recombination's rate of e⁻/h⁺ pairs. The scavenging evaluations proved that the h+ and •O2- were two major photoactive species accomplishing the CIP and TCH photodegradation over MNO/g-CN under visible region. Our findings pave the way for the construction of efficient binary photocatalysts for antibiotic restitution.

Recent progress in nanomaterial-functionalized membranes for removal of pollutants.

Membrane technology has gained tremendous attention for removing pollutants from wastewater, mainly due to their affordable capital cost, miniature equipment size, low energy consumption, and high efficiency even for the pollutants present in lower concentrations. In this paper, we review the literature to summarize the progress of nanomaterial-modified membranes for wastewater treatment applications. Introduction of nanomaterial in the polymeric matrix influences membrane properties such as surface roughness, hydrophobicity, porosity, and fouling resistance. This review also covers the importance of functionalization strategies to prepare thin-film nanocomposite hybrid membranes and their effect on eliminating pollutants. Systematic discussion regarding the impact of the nanomaterials incorporated within membrane, toward the recovery of various pollutants such as metal ions, organic compounds, dyes, and microbes. Successful examples are provided to show the potential of nanomaterial-functionalized membranes for regeneration of wastewater. In the end, future prospects are discussed to develop nanomaterial-based membrane technology.

Synthesis and in situ sulfidation of molybdenum carbide MXene using fluorine-free etchant for electrocatalytic hydrogen evolution reactions.

Synthesizing MXenes from Mn+1AXn (MAX) phases using hazardous hydrogen fluoride is a common and effective method. However, fluorine termination on the basal planes and edges of the resulting MXenes is undesirable for the electrocatalytic hydrogen evolution reaction (HER), while oxygen (O), hydroxyl (OH), and sulfur (S) termination favors this reaction. Herein, we unveil a simple fluorine-free exfoliation and two-step vulcanization method for synthesizing molybdenum sulfide-modified molybdenum carbide (MoS2/Mo2CTx MXene, T = OH, O, S) for the HER in alkaline medium. Microwave-assisted hydrothermal treatment of the MAX phase (Mo3AlC2) with sodium hydroxide-sodium sulfide as an etching solution and thioacetamide as a source of sulfide ions enabled the selective dissolution of the aluminum (Al) layer and sulfidation of the surface Mo atoms to form amorphous MoS2. Thus, the vulcanization of Mo2CTx MXene resulted in the formation of MoS2/Mo2CTx MXene. The MoS2 formed on the surface of Mo2CTx provided enhanced stability by preventing oxidation. MoS2/Mo2CTx exhibited enhanced electrocatalytic activity toward the HER, mainly due to the O, OH, and amorphous MoS2 functionalities. The MoS2 sites on the surface exhibited an overpotential of 110 ± 7 mV at a current density of 10 mA cm-2 as a result of enhanced charge transfer and mass transfer. Thus, the sulfidation method demonstrated herein is capable of producing amorphous MoS2 structures on Mo2CTx MXene, which could be applied for the surface modification of other molybdenum-based nanomaterials or electrocatalysts to improve stability and enhance electrocatalytic activity.

Bio-nanocomposite based highly sensitive and label-free electrochemical immunosensor for endometriosis diagnostics application.

In this research, for the first time, a bio-nanocomposites based highly sensitive and label-free electrochemical immunosensor is reported with the aim of endometriosis diagnostics application. Multiwalled carbon nanotube and magnetite nanoparticle (MWCNT-Fe3O4) was dispersed in chitosan (CS) to fabricate a bio-nanocomposite to immobilize very monoclonal specific antibody (via cross-linking using glutaraldehyde) for selective electrochemical immuno-sensing of carbohydrate antigen 19-9 (CA19-9), a potential biomarker for endometriosis diagnostics. Well-characterized Anti-AbsCA19-9/CS-MWCNT-Fe3O4 immune-electrode fabricated on glassy carbon electrode (GCE) successfully detect CA 19-9 and exhibited a high sensitivity as (2.55 µA pg-1 cm-1), a detection limit of 0.163 pg mL-1, detection range from 1.0 pg mL-1 to 100 ng mL-1. Our fabricated electrochemical AbsCA19-9/CS-MWCNT-Fe3O4 immunosensor performed CA19-9 sensing in physiological range and at a very level which suggest it application for early-stage diagnostics, diseases monitoring, and optimization of therapy. To claim the clinical application, our sensor was tested using real samples and sensing performance was validated using enzyme-linked immune-sorbent assay (ELISA). The results of the studies projected AbsCA19-9/CS-MWCNT-Fe3O4 electrochemical CA19-9 immunosensor as a potential and affordable alternate of conventional techniques like ELISA. We believe that our fabricated sensor can be the plane of a disease's management program due to affordable, rapid, label-free, and sensitive detection of a targeted biomarker.

Catalytic and photoresponsive BiZ/CuxS heterojunctions with surface vacancies for the treatment of multidrug-resistant clinical biofilm-associated infections.

We report a one-pot facile synthesis of highly photoresponsive bovine serum albumin (BSA) templated bismuth-copper sulfide nanocomposites (BSA-BiZ/CuxS NCs, where BiZ represents in situ formed Bi2S3 and bismuth oxysulfides (BOS)). As-formed surface vacancies and BiZ/CuxS heterojunctions impart superior catalytic, photodynamic and photothermal properties. Upon near-infrared (NIR) irradiation, the BSA-BiZ/CuxS NCs exhibit broad-spectrum antibacterial activity, not only against standard multidrug-resistant (MDR) bacterial strains but also against clinically isolated MDR bacteria and their associated biofilms. The minimum inhibitory concentration of BSA-BiZ/CuxS NCs is 14-fold lower than that of BSA-CuxS NCs because their multiple heterojunctions and vacancies facilitated an amplified phototherapeutic response. As-prepared BSA-BiZ/CuxS NCs exhibited substantial biofilm inhibition (90%) and eradication (>75%) efficiency under NIR irradiation. Furthermore, MRSA-infected diabetic mice were immensely treated with BSA-BiZ/CuxS NCs coupled with NIR irradiation by destroying the mature biofilm on the wound site, which accelerated the wound healing process via collagen synthesis and epithelialization. We demonstrate that BSA-BiZ/CuxS NCs with superior antimicrobial activity and high biocompatibility hold great potential as an effective photosensitive agent for the treatment of biofilm-associated infections.

Cost-effective single-step synthesis of flower-like cerium-ruthenium-sulfide for the determination of antipsychotic drug trifluoperazine in human urine samples.

Nanostructured binary metal sulfides are considered as a promising electrode material because of their excellent electron transfer and good sensing behavior rather than metal oxides. As a result, the binary metal sulfides were applied in energy and electrochemical sensor applications. Herein, we propose the electrochemical sensor method based on flower-like cerium-ruthenium sulfide nanostructure (Ce-Ru-S NS) for the electrochemical sensing of trifluoperazine (TFPZ). The Ce-Ru-S NS prepared using the cost-effective one-pot hydrothermal synthesis technique. Then, the resultant materials were characterized through suitable spectrophotometric techniques and the electrocatalytic properties of the fabricated sensor were investigated by EIS, CV, and amperometric (i-t) techniques. The Ce-Ru-S material has good electrocatalytic activity towards the electrochemical oxidation of TFPZ. Significantly, the fabricated sensor demonstrates the distinct amperometric response with the lowest limit of detection (LOD) of 0.322 nM (S/N = 3), high sensitivity 2.682 µA µM-1 cm-2 and lowest oxidation potential of +0.64 V (Ag/AgCl). Furthermore, the Ce-Ru-S NS displays excellent selectivity, good reproducibility, and long-term stability. The practicability of the TFPZ sensor tested in a human urine sample.

Label-Free Electrochemical Immunosensor Based on One-Step Electrochemical Deposition of AuNP-RGO Nanocomposites for Detection of Endometriosis Marker CA 125.

Endometriosis is the third most prominent gynecological disorder. Cancer antigen 125 (CA 125) is the primary serum marker used for late-stage endometriosis diagnosis and management. Herein, we developed a label-free immunosensor for electrochemical detection of CA 125 for endometriosis blood serum samples. The sensor was fabricated by one-step electrochemical deposition of highly conductive gold nanoparticles (AuNPs) and reduced graphene oxide (RGO) nanocomposite, via one-step electrochemical deposition. This method involved in situ reduction of HAuCl3 and graphene oxide and increased electrocatalytic performance. Different analytical techniques confirmed the morphology and structure of the AuNP/RGO nanocomposite. In addition, the antibody (Ab) was immobilized on the modified electrode surface through the self-assembly monolayer. The square wave voltammetry method has been utilized to measure the interaction of Ab and antigen (Ag). The as-fabricated sensor demonstrates a dynamic linear range of 0.0001 → 300 U mL-1 and lower limit of detection is 0.000042 U mL-1 toward CA125 detection. The developed sensor provides acceptable stability, high selectivity, and reproducibility. The proposed immunosensor has been applied to the CA 125 detection in endometriosis patient blood samples, and the results confirm the reliability of the as-fabricated sensor that is further associated with the standard ELISA analysis. The AuNP/RGO-based sensor can be used as an excellent tool for future prospective clinical diagnostics applications.