Applied Nanoscience最新文献

The requirement for passive thermal regulation in portable electronic devices enabled by 5G has escalated due to the significant heat produced during the operation of devices, resulting in a detrimental rise in human body temperature and reduced device longevity. This article explores various materials, such as hydrogels, metal–organic frameworks (MOFs), and phase-change materials (PCMs), which utilize natural convection and radiation to dissipate heat from the device, and their potential challenges and solutions for improvement. Hydrogels are not an optimal material due to their lack of cyclic stability and limited water adsorption capability, while MOFs are expensive and PCMs struggle with internal leakage during the solid-to-liquid transition. Thus, insights into novel hybrid materials and their potential for thermal resistance have been discussed. The study considers material marketing and sustainability. To enhance material performance, early-stage inclusion of recyclable, biomass-derived, or environmentally beneficial materials is recommended. Addressing the heat issue in 5G-enabled portable electronics, the article introduces practical passive thermal management materials.

The antibacterial properties of cicada wings originate from hexagonally arranged pillar-like multi-functional nanostructures with species-dependent heights, which are super-hydrophobic and self-cleaning. In the present study, two cicada species with promising nanopillars were investigated in more detail. Selected methods were used to analyze the wing surfaces, including Atomic Force Microscopy, Scanning Electron Microscopy, and bacterial tests with live/dead staining. Verifying the antibacterial properties posed challenges, such as the bacteria concentration needed to confirm the antibacterial properties. These challenges will also impact the practical implementation of antibacterial nanostructures and support the findings of recent critical publications.

The present study investigates the synthesis of vertically aligned MnO₂ nanowires (NW) decorated with gold (Au) and silver (Ag) nanoparticles (NP) via the glancing angle deposition (GLAD) technique without a need for a catalyst. The cross-sectional field emission scanning electron microscopy (FESEM) image and energy-dispersive X-ray spectroscopy (EDS) confirm the successful adornment of Ag NP and Au NP on the top surface of MnO₂ NW. Elemental mapping has verified the presence of manganese (Mn), oxygen (O), silicon (Si), Ag, and Au within the sample. X-ray diffraction (XRD) patterns reveal the polycrystalline growth of the MnO₂ film with the preferred orientation. AFM reveals that the surface roughness of Au NP/MnO₂ NW is more than Ag NP/MnO₂ NW. The measured water contact angles of Au NP/MnO₂ NW, Ag NP/MnO₂ NW, and MnO₂ NW were 125° and 113°, respectively. Ag NP/MnO₂ NW showed more hydrophilic properties under UV illumination than Au NP/MnO₂ NW owing to the efficient separation of photogenerated electron–hole pairs. Ag NP/MnO₂ NW’s higher photocatalytic activity than Au NP/MnO₂ NW is attributed to the increased light absorption of the Ag NP in the UV region. The overall enhancement after decorating the noble metal NP on MnO₂ NW could open new avenues for self-cleaning applications.

Copper nanoparticles (CuNPs) have drawn considerable interest because of recent evidences on greater Surface Enhanced Raman Spectroscopic (SERS) signal enhancing capability, high antibacterial activity and strong catalytic property with regard to the long existing popular silver and gold particles. The existing chemical synthesis methods usually require extensive purification to remove unreacted inorganic reducing agents, like sodium borohydride used to convert Cu²⁺ ions to Cu⁰ and it limits direct use of as-prepared materials in biologic systems. Here, we have endeavored to synthesize starch encapsulated CuNPs through radiation chemical approach which is considered to be one of the cleanest routes and involve in-situ generated hydrated electrons to reduce metal ions directly. Presence of large number of hydroxyl groups within starch molecules facilitates complexation of Cu(II) and thereby stabilizes CuNPs. Transmission electron microscopy (TEM) coupled with selected area electron diffraction (SAED) illustrate that particles synthesized at a typical dose of 83.6 kGy are spherical with size of ca. 8 nm having polycrystalline face-centered cubic phase. The observed blue shift of the absorption maximum suggests formation of smaller sized particles with increase in applied radiation dose keeping other parameters same and this is supported by dynamic light scattering (DLS) data. Further, catalytic efficiency of as-synthesized CuNPs was tested by monitoring sodium borohydride mediated catalytic reduction of para-nitrophenol to para-aminophenol and the apparent rate constant (k_app) was estimated as 3 × 10^–3 s⁻¹. Thus, as-synthesized CuNPs appears to be better catalyst than the copper nanoparticles synthesized through conventional method for having k_app of about 1.6 × 10^–3 s⁻¹.

Nanozymes, possessing enzyme-like traits, have gained tremendous attention for their functionality, ease of production, economical synthesis, and stability. Majority of reported nanozymes in literature, for analyte detection are metal-based compounds, transition metal dichalcogenides or single-atom nanozymes. In this study, we report for the first time, a novel peroxidase-mimic, colloidal dendritic nanozyme from lignin-rich agro-industrial residue (coconut husk) by ozonolysis. Synthesized nanozyme exhibited peroxidase-mimic activity in sensing H₂O₂, with a wide range of substrates and detection techniques. When 3,3′,5,5′-tetramethylbenzidine (TMB) and 2′,7′–dichlorofluorescin diacetate (DCFDA) were used, the nanozyme demonstrated ultrafast kinetic behaviour with LOD of 43.60 ± 2.41 µM and 1.25 ± 0.31 µM H₂O₂, by colorimetric and fluorimetric assays, respectively. The nanozyme-based H₂O₂ sensing platform, was further utilized for detection of pathogenic bacteria namely Escherichia coli, Listeria monocytogenes, Staphylococcus aureus and Pseudomonas aeruginosa, and for total bacterial load in water. Notably, it demonstrated high sensitivity in the detection of P. aeruginosa with LOD as low as 7 CFU/mL with both fluorimetric and electrochemical methods. Ultrasensitive detection of total bacterial load could also be achieved with 5.5 × 10² CFU/mL, 5.5 × 10¹ CFU/mL, and 4.1 × 10¹ CFU/mL by colorimetric, fluorometric, and electrochemical techniques, respectively. Results of the study thus indicate, that the developed nanozyme-based sensing platform had high sensitivity for detection of bacteria as well as versatility with diverse analytical approaches enabling potential practical application for “onsite” monitoring of water quality, especially in rural settings. This biological mimic can also be used in sensor platforms where H₂O₂ is measured and applied for output signaling.

To properly exploit undepleted sources of energy through energy conversion devices using water splitting reactions, there is a need for cost-effective, easily accessible, and long-lasting materials that are capable of performing bifunctional activity like hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). In this study, oxygen incorporation into SnS@Cu₂S (O-SnS@Cu₂S) heteronanosheets was architecture on Nickel foam utilizing polyoxometalate as bimetal precursors, and then this material exhibited superior activity, requiring only a small overpotential to generate high current densities compared to individual O-SnS and O-Cu₂S arrays for the electrocatalytic HER activity. The Tafel slopes (26 mV dec⁻¹) and electrochemical impedance spectroscopy (EIS) (R_ct = 1.2 Ω), further confirmed the favorable kinetics and conductivity of the O-SnS@Cu₂S array. When compared to the O-Cu₂S and O-SnS nanosheet arrays, the bimetal sulphides O-SnS@Cu₂S array had much lower overpotentials, requiring only 170 mV and 232 mV, respectively, to achieve a current density of 10 mA cm⁻² in an alkaline solution for HER and OER. The O-SnS@Cu₂S nanosheet array outperformed SnS and Cu₂S, requiring lower overpotentials to achieve high current densities. The smaller value of Tafel slopes (23 mV dec⁻¹ for O-SnS@Cu₂S) indicated improved kinetics, and EIS demonstrated a lower polarization resistance (R_ct = 0.2 Ω) for the O-SnS@Cu₂S array. Importantly, the O-SnS@Cu₂S array exhibited remarkable stability in alkaline electrolyte cycling experiments, making it an outstanding material for practical applications in energy conversion devices. This research proposes a feasible technique for the development of efficient and stable bifunctional bimetal-sulfide electrocatalysts with enormous potential for use in renewable energy.

This study explains the potential role of non-functionalized graphene produced using flash joule heating technology on Drosophila melanogaster. Several characterizations of the produced graphene were conducted via field emission-scanning electron microscopy, high-resolution transmission electron microscopy, Raman spectroscopy, and X-ray diffraction studies. After being characterized, the graphene powder was orally administered to flies at doses ranging from 0.02 to 0.5%, establishing its non-toxic properties as a prerequisite for potential therapeutic applications. Experiments such as Trypan blue and 4’,6-diamidino-2-phenylindole (DAPI) revealed that graphene causes no harm to the larval gut’s plasma membrane and nucleus. Behavioral assays such as crawling and climbing assays on larvae and adults demonstrated the non-neurotoxic nature of graphene. The high sucrose diet-induced diabetic Drosophila melanogaster model was used to study antidiabetic properties. In contrast, Gram + ve bacteria B. subtilis and Gram − ve P. aeruginosa were used to study the antibacterial properties of graphene. A better metabolic profile was evidenced after graphene treatment, including a 36% decrease in hemolymph-free glucose levels and significantly reduced lipid droplets at the highest concentration. In addition, the highest concentration of graphene treatment resulted in a 57% reduced fluorescent intensity of reactive oxygen species (ROS) produced by diabetic flies. Considering all these evidence, this study concludes that graphene’s non-toxic and antidiabetic properties can be used to mitigate the symptoms associated with Type II diabetes and obesity.

The extraordinary physical properties of multiwalled carbon nanotubes (MWCNTs) are yet to be fully realised in polyamide-6 (PA6) nanocomposites, due to difficulty in dispersion of MWCNTs within PA6 matrix, owing to high toughness of PA6 and agglomerating properties of MWCNTs. In this study, MWCNTs of high aspect ratio prepared by chemical vapour deposition (CVD) method are melt-mixed with 0.1–0.5 parts-per-hundred ratios (phr) into PA6 matrix by twin-screw extrusion. The high shearing force of co-rotating twin-screws and intermixing of the components along the back-flow channel of extruder assured uniformly dispersed MWCNTs within PA6 system. A 30.2% rise in yield strength and an 82.6% rise in Young’s modulus were noticed for 0.1 phr MWCNTs/PA6 tensile specimens over neat PA6 specimens during tensile testing. A strain hardening behaviour was shown by neat PA6, which was persistent in all its composites containing MWCNTs. A distinct trend in storage and loss behaviour, as well as 14 °C and 11 °C rise in glass transition temperatures (T_g) in loss modulus and loss factor curves, respectively, were observed for 0.5 phr MWCNTs’ reinforcement in dynamic mechanical analysis (DMA), which indicated an effective PA6–MWCNTs interaction. The improvements in crystallization and melting temperatures, as well as crystallinity values in differential scanning calorimetry (DSC) indicated nucleating effects of MWCNTs towards stable crystallization of PA6 molecules. The shifting and rise in intensity peaks in XRD and Raman spectroscopy curves supported the reinforcing effect of MWCNTs within PA6 matrix. These nanocomposites are beneficial for fabricating high mechanical and thermal stability-required components in automobiles, aerospace, and biomedicals.