Heterogenized Cu(II) complex of 5-aminotetrazole immobilized on graphene oxide nanosheets as an efficient catalyst for treating environmental contaminants

Antimicrobial Properties of Azole Functional Silica Nanocomposites

Silica nanoparticles have become more attractive due to their surface characteristics, versatility, biocompatibility, and morphological and physicochemical properties. For this reason, their use in biological applications has been expanding in recent years. In this study, after functionalizing silica nanoparticles with glycidyl methacrylate monomer, nanocomposites were formed by attaching 1,2,4‐Triazole, 3‐Amino‐1,2,4‐Triazole, and 5‐Aminotetrazole particles to the surface. Notably, the thermal degradation temperature of all nanocomposites was determined to surpass 200 °C. However, it is worth mentioning that despite the favorable water uptake rates observed for MT(7.64 %) and M3(5.98 %) nanocomposites, MT did not exhibit resistance against Fenton chemicals and experienced degradation. It is important to note that the material loss in M3 nanocomposites is minimal, measuring less than 1 %. In order to reveal the antifungal and antibacterial activity of the synthesized nanoparticles, Minimum inhibitory concentration(MIC), as well as Minimum Fungicidal Concentration(MFC) against the yeast strain Saccharomyces cerevisiae, and Minimum Bactericidal Concentration(MBC) values against bacteria strains, Staphylococcus aureus, Enterococcus faecalis and Escherichia coli were determined. The findings of the study indicated that MP, M3, and M5 nanocomposites displayed a moderate level of antibacterial activity. It is noteworthy, however, that the antibacterial activity diminished when triazole was combined with MP at concentrations exceeding 100 mg/mL.

Wearable Two-Dimensional Nanomaterial-Based Flexible Sensors for Blood Pressure Monitoring: A Review

Flexible sensors have been extensively employed in wearable technologies for physiological monitoring given the technological advancement in recent years. Conventional sensors made of silicon or glass substrates may be limited by their rigid structures, bulkiness, and incapability for continuous monitoring of vital signs, such as blood pressure (BP). Two-dimensional (2D) nanomaterials have received considerable attention in the fabrication of flexible sensors due to their large surface-area-to-volume ratio, high electrical conductivity, cost effectiveness, flexibility, and light weight. This review discusses the transduction mechanisms, namely, piezoelectric, capacitive, piezoresistive, and triboelectric, of flexible sensors. Several 2D nanomaterials used as sensing elements for flexible BP sensors are reviewed in terms of their mechanisms, materials, and sensing performance. Previous works on wearable BP sensors are presented, including epidermal patches, electronic tattoos, and commercialized BP patches. Finally, the challenges and future outlook of this emerging technology are addressed for non-invasive and continuous BP monitoring.

Synthesis of bentonite/Ag nanocomposite by laser ablation in air and its application in remediation

In this research, a simple, green, and efficient approach is described to produce novel bentonite/Ag nanocomposite wherein the preparation of Ag nanoparticles (Ag NPs) deployed the laser ablation method in air; Ag NPs are deposited on the bentonite via the magnetic stirring method. The structural and morphological characterization of the as-prepared bentonite/Ag nanocomposite (denoted as B/Ag30, 30 min being the laser ablation time) is accomplished using different methods. Additionally, the catalytic assessment of the ensued composite exhibited excellent catalytic reduction/degradation activity for common aqueous pollutants namely methyl orange (MO), congo red (CR) and 4-nitrophenol (4-NP) utilizing NaBH₄ as reductant. Furthermore, the recycling tests displayed the high stability/reusability of B/Ag30 nanocomposite for at least 4 runs with retention of catalytic prowess.

Synthesis and Characterization of rGO@ZnO Nanocomposites for Esterification of Acetic Acid

In the present work, the aim is to synthesize reduced graphene oxide (rGO) and zinc:reduced graphene oxide composite catalysts (ZnO:rGO) for esterification of acetic acid with n-heptanol. The physical and chemical characteristics of the rGO and rGO-metal oxide composite catalysts such as textural surface characteristics, surface morphology, thermal stability, functional groups, and elemental analysis were studied. The surface areas of rGO, ZnO_(0.5 M), and ZnO_(1 M) were recorded, respectively, at 31.72, 27.65, and 36.19 m² g^-1. Furthermore, esterification reaction parameters such as the reaction time, catalyst dosage, and reaction temperature for acetic acid were optimized to check the feasibility of rGO-metal oxide composites for a better conversion percentage of acetic acid. The optimized catalyst was selected for further optimization, and the optimum reaction parameters found were 0.1 wt % of catalyst, 160 min reaction duration, and 100 °C reaction temperature with a maximal yield of 100%. At 110 °C, the reaction conducted in the presence of 0.1 g of catalyst displayed more yield than the uncatalyzed reaction.

Copper(II)-Bis-Cyclen Intercalated Graphene Oxide as an Efficient Two-Dimensional Nanocomposite Material for Copper-Catalyzed Azide–Alkyne Cycloaddition Reaction

We report stable and heterogeneous graphene oxide (GO)–intercalated copper as an efficient catalyst for the organic transformations in green solvents. The GO-intercalated copper(II) complex of bis(1,4,7,10-tetraazacyclododecane) [Cu(II)-bis-cyclen] was prepared by a facile synthetic approach with a high dilution technique. The as-prepared GO-Cu(II)-bis-cyclen nanocomposite was used as a click catalyst for the 1,3 dipolar Huisgen cycloaddition reaction of terminal alkyne and azide substrates. On directing a great deal of attention toward the feasibility of the rapid electron transfer rate of the catalyst in proliferating the yield of 1,2,3-triazole products, the click catalyst GO-Cu(II)-bis-cyclen nanocomposite was designed and synthesized via non-covalent functionalization. The presence of a higher coordination site in an efficient 2D nanocomposite promotes the stabilization of Cu(I) L-acetylide intermediate during the catalytic cycle initiated by the addition of reductants. From the XRD analysis, the enhancement in the d-interlayer spacing of 1.04 nm was observed due to the intercalation of the Cu(II)-bis-cyclen complex in between the GO basal planes. It was also characterized by XPS, FT-IR, RAMAN, UV, SEM, AFM, and TGA techniques. The recyclability of the heterogeneous catalyst [GO-Cu(II)-cyclen] with the solvent effect has also been studied. This class of GO-Cu(II)-bis-cyclen nanocomposite paves the way for bioconjugation of macromolecules through the click chemistry approach.

From methylarenes to Esters: Efficient oxidative Csp3-H activation promoted by CuO decorated magnetic reduced graphene oxide

Magnetic reduced graphene oxide supported CuO (rGO/Fe3O4-CuO) as the heterogeneous catalyst in cross dehydrogenative coupling (CDC) reactions has been demonstrated for the synthesis of esters using methyl aromatics, aldehydes/benzyl alcohols...

Transformation of CuS/ZnS nanomaterials to an efficient visible light photocatalyst by 'photosensitizer' graphene and the potential antimicrobial activities of the nanocomposites

We report the growth of CuS/ZnS (CZS) nanoparticles (NPs) on the graphene sheet by a facile green synthesis process. The CuS/ZnS-graphene (CZSG) nanocomposites exhibit enhanced visible light photocatalytic activity towards organic dye (methylene blue) degradation than that of CZS nanoparticles. To find the reason for the enhanced photo-activity, we propose a new photocatalytic mechanism where graphene in the CZSG nanocomposites acts as a 'photosensitizer' for CZS nanoparticles. This distinctive photocatalytic mechanism is noticeably different from all other previous research works on semiconductor-graphene hybrid photocatalysts where graphene behaves as an electron reservoir to capture the electrons from photo-excited semiconductor. This novel idea of the photocatalytic mechanism in semiconductor-graphene photocatalysts could draw a new track in thinking for designing of graphene-based photocatalysts for solving environmental pollution problems and they also show remarkable antimicrobial activities.

Immobilization of Cu (II) via a graphene oxide-supported strategy for antibacterial reutilization with long-term efficacy

The past several decades have witnessed tremendous research to discover ways for controlling heavy metal pollution, but most of the strategies do not involve reuse of the captured heavy metals. Herein, we propose a graphene oxide -based strategy for the effective removal of Cu²⁺ ions from water, coupled with their reuse as an antibacterial agent. Using GO nanosheets as an adsorbent and nanosupport, the Cu²⁺ ions were effectively extracted from water (>99.9%) and reduced in situ to copper nanoparticles (Cu NPs) containing both crystalline Cu and Cu₂O. The as-captured Cu NPs showed efficient in vitro antibacterial ability against Escherichia coli, reducing the bacteria from 10⁹ to 10¹ CFU mL^-1 by using ¹ mg mL^-1 Cu NPs/GO NSs for 1 h. The minimum inhibitory concentration determined to be only 16 μg mL^-1. For practical applications, Cu recovered from wastewater could reduce bacteria by 8 log CFU in 1 h. The recovered Cu was still able to reduce the bacteria by 7 log CFU after 2 months of storage in an argon atmosphere. This strategy of extracting heavy metals and subsequently reutilizing to kill bacteria will be of great significance for environmental remediation and public healthcare.