Fabrication and Evaluation of the Photocatalytic, Antibacterial Activity of Ag–TiO2_2 Thin Film

Ag–TiO2 thin film was fabricated by DC magnetron sputtering and photoreduction methods. Characteristics of the film such as surface area, crystal structure, and chemical composition were investigated by using scanning electron microscope (SEM), X–ray diffractometry (XRD) and UV–vis spectra. The photocatalytic activity of Ag–TiO2 thin film was determined by the degradation of methylene blue (MB) solution under various irradiation conditions. The antibacterial property of Ag–TiO2 thin film was conducted in E. coli bacteria. Results showed that the photocatalytic and antibacterial property of Ag–TiO2 thin film are better than those of pure TiO2 thin film in the visible region. Ag–TiO2 thin film shows a great potential application in the antibacterial and environment field

TiO 2

An improved photocatalytic activity of semiconductor materials using incorporation of the noble metals such as Ag, Au, and Pt is a promising technology. In this study, Ag nanoparticle-TiO2 nanotube structures (Ag-TNTs) have been investigated as a photocatalyst in different irradiation conditions using different characterization techniques. The results indicate that Ag nanoparticles dispersed uniformly on the TNTs’ surface without any change in TNTs’ morphology. In addition, Ag-TNTs exhibited lower photoactivity than the TNTs under UV irradiation. In contrast, Ag-TNTs increased the photoactivity in comparison with TNTs and the photocatalytic performance under sunlight irradiation. These phenomena could be contributed to the appearance of Ag nanoparticles on the nanotube surface

Spatiotemporal evolution of SARS-CoV-2 Alpha and Delta variants during large nationwide outbreak of COVID-19, Vietnam, 2021

We analyzed 1,303 SARS-CoV-2 whole-genome sequences from Vietnam, and found the Alpha and Delta variants were responsible for a large nationwide outbreak of COVID-19 in 2021. The Delta variant was confined to the AY.57 lineage and caused >1.7 million infections and >32,000 deaths. Viral transmission was strongly affected by nonpharmaceutical interventions

Multifunctional engineering on the ultrasensitive driven-dual plasmonic heterogenous dimer system of 1D semiconductor for accurate SERS sensitivity and quantitation

Self-assembled functional nanomaterials with electromagnetic (EM) hot spots and chemical (CM) enhancement have been recognized as a key in surface-enhanced Raman scattering (SERS) analysis. Herein, a dual-hybrid plasmonic coupling SERS sensor composed of rutile TiO2 nanorod arrays (r-TNRs), Au nanospheres (AuNSs), and Ag nanocubes (AgNCs) has been designed to achieve ultrasensitive detection and obtain unique molecular fingerprints. The AgNCs/AuNSs/r-TNRs-based SERS chip shows an extremely promising SERS enhancement factor (EF) of 1.2 ×1011, detectability at sub-picomolar concentrations (down to the single-molecule level, 10-13 M), and excellent signal reproducibility with a relative standard deviation (RSD) of 3.4 %. Furthermore, this system has been applied for fingerprint detection in complex mixtures, demonstrating impressive specificity and accuracy. The photocatalytic decomposition efficiency of the AgNCs/AuNSs/r-TNRs platform reaches approximately ∼99 % within 20 min. Additionally, the Raman intensity of crystal violet only declined by 15 % after 21 days, illustrating the outstanding stability of the as-proposed ternary SERS sensor

Hotspot-type silver-polymers grafted nanocellulose paper with analyte enrichment as flexible plasmonic sensors for highly sensitive SERS sensing

High order plasmonic types by integrating a novel heterogeneous plasmonic and flexible model based on the co-existence of Ag nanospheres (NSs) and Ag nanocubes (NCs) are introduced. The point-to-facet type in these hybrid shapes produces surface-enhanced Raman scattering (SERS) signals many-fold larger than in single-plasmonic constructs. A high enhancement factor (EF = 4.6 × 108) in coupled plasmonic particulates allowed SERS-probing at ultralow sample quantities. Then, these plasmonic constructs are anchored onto a flexible polymethyl methacrylate (PMMA)-treated cellulose paper. In addition to strong electromagnetic enhancement, the hydrophobic surface could concentrate target analytes in the hotspot areas, resulting in highly active SERS responses in highly diluted solutions. As a result, the flexible SERS sensing platform exhibits high sensitivity with detection around 10−10 M and point-to-face relative standard deviation (RSD) in one sensor as low as 7.28%, thereby demonstrating good reproducibility. Furthermore, it exhibits perfectly selective detection for trace amounts of interest analytes in a complex solution, significantly enhancing the analyte identification efficiency at nanomolar concentration levels. This study has proven a promising route for an integrated SERS platform with plasmonic nanoconstructs and analyte enrichment as a versatile SERS sensor for highly sensitive, quantitative, selective, and cost-effective SERS detection