Metal–metal bonding using silver/copper nanoparticles

Fabrication of a sustainable superhydrophobic surface of Ag-NPs@SA on copper alloy for corrosion resistance, photocatalysis, and simulated distribution of Ag atoms

Artificial superhydrophobic surfaces that do not absorb water, like the lotus leaf, show tremendous promise in numerous applications. However, superhydrophobic surfaces are rarely used because of their low stability and endurance. A stable organic superhydrophobic surface (SHS) composed of novel morphology Ag-nanoparticles (NPs) has been fabricated on a copper alloy via etching, immersion, spraying, and annealing treatment, along with a static water contact angle (WCA) of 158 ± 1° and sliding angle (SA) less than 2°. The surface texture, composition, and morphology of the substrate surfaces were explored by using X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, and DFT-based Ag atom distribution. The anti-corrosion study of non-coated and Ag-NP-coated copper alloy was undertaken using electrochemical impedance spectroscopy. Ag-NPs +SA@SHS enhanced the corrosion resistance as compared with bare Cu alloy. The water droplet rolled down the coated Cu alloy, removed the chalk powder from the surface, and indicated an excellent self-cleaning function. Photodegradation of Congo red (CR) and methylene blue (MB) dye samples was assessed by measuring the absorbance through UV-Visible spectrophotometry, where the Ag-NPs coated on the copper alloy were used as a catalyst. The performance of the SHS@Ag-NPs in the aqueous solution was 99.31% and 98.12% for industrial pollutants (CR and MB), with degradation rates of 5.81 × 10-2 s-1 and 5.89 × 10-2 s-1, respectively. These findings demonstrated a simple, rapid, and low-energy fabrication technique for SHS@Ag-NPs. This research reveals a valuable approach for the fabrication of SHS@Ag-NPs on various substrates to extend the superhydrophobic surfaces with ultra-fast self-healing properties, for outdoor applications such as anti-corrosion, for an innovative approach for the remediation of polluted water treatment, and for industrial applications.

Phytofabricated bimetallic synthesis of silver-copper nanoparticles using Aerva lanata extract to evaluate their potential cytotoxic and antimicrobial activities

In this study, we demonstrate the green synthesis of bimetallic silver-copper nanoparticles (Ag-Cu NPs) using Aerva lanata plant extract. These NPs possess diverse biological properties, including in vitro antioxidant, antibiofilm, and cytotoxic activities. The synthesis involves the reduction of silver nitrate and copper oxide salts mediated by the plant extract, resulting in the formation of crystalline Ag-Cu NPs with a face-centered cubic structure. Characterization techniques confirm the presence of functional groups from the plant extract, acting as stabilizing and reducing agents. The synthesized NPs exhibit uniform-sized spherical morphology ranging from 7 to 12 nm. They demonstrate significant antibacterial activity against Staphylococcus aureus and Pseudomonas aeruginosa, inhibiting extracellular polysaccharide secretion in a dose-dependent manner. The Ag-Cu NPs also exhibit potent cytotoxic activity against cancerous HeLa cell lines, with an inhibitory concentration (IC50) of 17.63 µg mL-1. Additionally, they demonstrate strong antioxidant potential, including reducing capability and H2O2 radical scavenging activity, particularly at high concentrations (240 µg mL-1). Overall, these results emphasize the potential of A. lanata plant metabolite-driven NPs as effective agents against infectious diseases and cancer.

Biosynthesis of Novel Ag-Cu Bimetallic Nanoparticles from Leaf Extract of Salvia officinalis and Their Antibacterial Activity

Bimetallic nanoparticles exhibit bifunctional or synergistic effects prevailing between two metals with the capabilities of enhanced electronic, catalytic, and optical properties. Green synthetic routes have gained tremendous interest because of the noninvolvement of toxic and harmful chemical reagents in preparation. Therefore, we develop bimetallic Ag-Cu nanoparticles (Ag-Cu NPs) through an eco-friendly and biocompatible preparation method. In this study, Ag-Cu NPs have been synthesized from leaf extracts of the commonly known sage, S. officinalis. The extract has a rich phytochemical composition, including bioreducing polyphenols, flavonoids, and capping/stabilizing agents. An array of well-known spectroscopic and microscopic techniques were used to characterize the as-prepared Ag-Cu bimetallic nanoparticles, including X-ray diffraction (XRD), ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy, transmission electron microscopy, and energy-dispersive X-ray spectroscopy. The size of the Ag-Cu NPs was found to be 50 nm with a spherical shape and an almost uniform distribution. The antibacterial effect was further evaluated using agar well diffusion and disc diffusion assays. Ag-Cu NPs exhibit antibacterial and antibiofilm properties against Gram-positive and Gram-negative bacteria strains. The minimum inhibitory concentration (MIC) of Ag-Cu NPs was between 5 g/mL and 15 g/mL. The Ag-Cu NPs inhibit biofilm formation at 25 g/mL and 50 g/mL. The results of biogenic Ag-Cu NPs provide novel antibacterial activity against Gram-positive and Gram-negative bacteria, as well as antibiofilm activity. Hence, Ag-Cu NPs might serve as a novel antibacterial agent with potential antibacterial and antibiofilm properties.

Multifunctional and Sensitivity Enhancement of Hybrid Acoustoplasmonic Sensors Fabricated on 36XY-LiTaO3 with Gold Nanoparticles for the Detection of Permittivity, Conductivity, and the Refractive Index

Integration of high-sensitivity sensors with multiple sensing performance for the environmental detection of permittivity (ε_r), conductivity (σ), and the refractive index (n) is required to support Societies 5.0. However, there are still many sensors with low sensitivity that stand alone. A shear-horizontal surface acoustic wave (SH-SAW) sensor is usually used because of its high-sensitivity performance in detecting electrical properties. Moreover, localized surface plasmon resonance (LSPR) sensors show remarkable optical side capability. Here, we have successfully combined these advantages with an additional benefit of sensitivity enhancement. We propose a hybrid acoustoplasmonic sensor generated by integrating SH-SAW and LSPR devices to simultaneously detect ε_r, σ, and n. The SH-SAW sensor was fabricated on a 36XY-LiTaO₃ substrate using a developed interdigital transducer. Then, the LSPR sensor was implemented by the deposition of gold nanoparticles (AuNPs) on the propagation surfaces of the SH-SAW sensor. Fascinatingly, the AuNPs not only generate the LSPR effect but also enhance the SH-SAW sensor sensitivity. Comprehensive investigations were performed with atomic force microscopy imaging, CST software used for plasmonic E-field simulation, and hybrid sensing evaluation. Moreover, the SH-SAW sensitivity enhancement achieved using AuNPs was verified by frequency-domain and time-domain measurements. Thus, the SH-SAW sensor with AuNPs has a wide ε_r detection range (25-85), sensing capabilities for ultrasmall σ (0.00528-0.02504 S/m), and high sensitivity for n detection (45.5-201.9 nm/RIU). The cross-sectional effects were also evaluated. The effect of the LSPR device on the SH-SAW device was examined by turning the light OFF or ON (hereafter OFF/ON). The impact of the SH-SAW device on the LSPR device was investigated by turning the sine signal OFF/ON. We found that the SH-SAW sensor was not impacted by light. Interestingly, the presence of the SH-SAW sensor affects the positions of the AuNPs, which consistently generates a small blueshift in the LSPR effect. However, insignificant variation was noted in independent performances. In general, the SH-SAW sensor with AuNPs shows multifunctional independent characteristics and high-sensitivity performance, making it suitable for a chemical environment, with the possibility of integration with a wireless network.