Bi2O3 nano-flakes as a cost-effective antibacterial agent

Bi2W2O9 Nanoflakes Synthesized via a Hydrothermal Method: Antibacterial Potency and Cytotoxicity Evaluation on Human Dermal Fibroblasts

The prevalence of disease and death caused by pathogenic microbes is on the rise, and increasing rates of antibiotic resistance are concerning. This study investigates the antibacterial properties and cell viability (NHDF) behavior of synthesized Bi2W2O9 nanoflakes. The Bi2W2O9 nanoflakes were synthesized using the hydrothermal method, and their physical and compositional stability was analyzed through various characterization techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR), Raman, and DRS-UV. The Bi2W2O9 nanoflakes demonstrated promising antibacterial properties, with no significant cytotoxic effects, such as cell death or detachment, observed. This study confirms that Bi2W2O9 nanoflakes exhibit antibacterial activity against oral pathogens while maintaining 90% cell viability in normal human dermal fibroblast cell lines, paving the way for new therapeutic options for the treatment of oral infections.

Comparison of X-Ray Attenuation Performance, Antimicrobial Properties, and Cytotoxicity of Silicone-Based Matrices Containing Bi2O3, PbO, or Bi2O3/PbO Nanoparticles

Background

Application of the nanomaterials to preparing X-ray shields and successfully treating multiresistant microorganisms has attracted great attention in modern life.

Objective

This study aimed to prepare flexible silicone-based matrices containing Bi2O3, PbO, or Bi2O3/PbO nanoparticles and select a cost-effective, cytocompatible, and antibacterial/antifungal X-ray shield in clinical radiography.

Material and Methods

In this experimental study, we prepared the nanoparticles by the modified biosynthesis method and fabricated the X-ray shields containing 20 wt% of the nanoparticles. The X-ray attenuation percentage and Half Value Layer (HVL) of the shields were investigated for the photon energies in the range of 40-100 kVp in clinical radiography. The antibacterial/antifungal activities of the shields were evaluated using a colony count method for the gram-negative (Escherichia coli), and gram-positive (Enterococcus faecalis) bacteria, and Candida albicans fungus. The shield toxicity was investigated on A549 cells.

Results

The highest X-ray attenuation percentage and the lowest HVL were obtained using the shield containing Bi2O3 nanoparticles. Although all shields displayed antimicrobial activity, the shield containing Bi2O3/PbO nanoparticles showed the most effective reduction in the colony counts. Both X-ray shields containing nano Bi2O3 and Bi2O3/PbO demonstrated high cytocompatibility on A549 cells at a concentration as high as 500 µg/ml. The shield with PbO nanoparticles was also cytocompatible at a concentration of 50 µg/ml.

Conclusion

The best X-ray attenuation performance is attributed to the silicone-based matrix with nano Bi2O3; however, the flexible shield with Bi2O3/PbO nanoparticles can be cost-effective and cytocompatible with the best antibacterial/antifungal properties.

Ultrathin α-Bi2O3 Thin-Film Transistor for Cost-Effective Oxide-TFT Inverters

Electronics is advancing toward greater diversity and sustainability by prioritizing energy efficiency and cost-effectiveness. Metal oxide thin-film transistor (TFT) represents a technology at the forefront of advancing next-generation sustainable electronics, and exploring oxide channel compositions is a crucial step in opening opportunities for developing next-generation device applications. This study presents the first development of n-channel α-Bi2O3-TFTs using a 4 nm ultrathin channel prepared by a cost-effective vacuum-free and solvent-free liquid metal printing method in ambient air. Even the pristine device exhibited a clear TFT action but required a large negative gate bias to turn off due mainly to excess carriers from oxygen vacancy in the α-Bi2O3 channel. Oxygen-containing post-annealing reduced both channel carrier and subgap defect densities, enabling the development of depletion and enhancement-type α-Bi2O3-TFTs with the saturation mobility of 2-4 cm2 V-1 s-1. Two types of oxide-TFT-based inverter circuits, zero-VGS-NMOS and CMOS inverters, were fabricated by using α-Bi2O3-TFTs, operating in a high voltage gain of over 130. This work demonstrates the potential of oxide semiconductor materials toward the development of next-generation sustainable electronics.

A comprehensive study on the co-removal of Cr (VI) and ciprofloxacin via microbial-photocatalytic coupling: Mechanistic insights and performance evaluation

The increasing contamination of water systems by antibiotics and heavy metals has become a growing concern. The intimately coupled photocatalysis and biodegradation (ICPB) approach offers a promising strategy for the effective removal of mixed pollutants. Despite some prior research on ICPB applications, the mechanism by which ICPB eliminates mixed pollutants remains unclear. In our current study, the ICPB approach achieved approximately 1.53 times the degradation rate of ciprofloxacin (CIP) and roughly 1.82 times the reduction rate of Cr (VI) compared to photocatalysis. Remarkably, after 30 days, the ICPB achieved a 96.1% CIP removal rate, and a 97.8% reduction in Cr (VI). Our investigation utilized three-dimensional fluorescence analysis and photo-electrochemical characterization to unveil the synergistic effects of photocatalysis and biodegradation in removal of CIP and Cr (VI). Incorporation of B-Bi3O4Cl (B-BOC) photocatalyst facilitated electron-hole separation, leading to production of ·O2-, ·OH, and h+ species which interacted with CIP, while electrons reduced Cr (VI). Subsequently, the photocatalytic products were biodegraded by a protective biofilm. Furthermore, we observed that CIP, acting as an electron donor, promoted the reduction of Cr (VI). The microbial communities revealed that the number of bacteria favoring pollutant removal increased during ICPB operation, leading to a significant enhancement in performance.

An ultrasensitive ratiometric electrochemical aptasensor based on metal-organic frameworks and nanoflower-like Bi2CuO4 for human epidermal growth factor receptor 2 detection

An ultra-sensitive ratiometric electrochemical aptasensor was constructed based on metal-organic frameworks (MOFs) and bimetallic oxides for the detection of the human epidermal growth factor receptor 2 (HER2), a breast cancer marker. The aluminum metal-organic framework (Al-MOF) and cerium-metal-organic framework (Ce-MOF) have higher specific surface area, which is conducive to load more aptamers or complementary DNA (cDNA), and realize the amplification of internal reference signal Fc. Furthermore, nanoflower-like bismuth copper oxide (Bi2CuO4) with abundant active sites was introduced to modify more aptamers on its surface, which were then fixed to the glassy carbon electrode (GCE) to amplify the detection signal. The quantitative detection of HER2 was achieved by differential pulse voltammetry (DPV), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The materials were characterized by scanning electron microscope, transmission electron microscope, Zeta potential analyzer, X-ray diffraction and X-ray photoelectron spectroscopy. The ratiometric electrochemical aptasensor based on nanomaterial and chain displacement signal amplification technology could discern HER2 in a very wide range (0.001-20.0 ng/mL) with an extremely low detection limit (0.049 pg/mL) and has demonstrated good performance in clinical serum analysis. This strategy also provides a feasible idea for sensitive analysis of other clinical tumor markers.

Synthesis of Antibacterial Copper Oxide Nanoparticles by Pulsed Laser Ablation in Liquids: Potential Application against Foodborne Pathogens

Spherical copper oxide nanoparticles (CuO/Cu2O NPs) were synthesized by pulsed laser ablation in liquids (PLAL). The copper target was totally submerged in deionized (DI) water and irradiated by an infrared laser beam at 1064 nm for 30 min. The NPs were then characterized by dynamic light scattering (DLS) and atomic emission spectroscopy (AES) to determine their size distribution and concentration, respectively. The phases of copper oxide were identified by Raman spectroscopy. Then, the antibacterial activity of CuO/Cu2O NPs against foodborne pathogens, such as Salmonella enterica subsp. enterica serotype Typhimurium DT7, Escherichia coli O157:H7, Shigella sonnei ATCC 9290, Yersinia enterocolitica ATCC 27729, Vibrio parahaemolyticus ATCC 49398, Bacillus cereus ATCC 11778, and Listeria monocytogenes EGD, was tested. At a 3 ppm concentration, the CuO/Cu2O NPs exhibited an outstanding antimicrobial effect by killing most bacteria after 5 h incubation at 25 °C. Field emission scanning electron microscope (FESEM) confirmed that the CuO/Cu2O NPs destructed the bacterial cell wall.

Study of the oxidation process of bismuth nanoparticles using NaClO

Bismuth nanoparticles (NPs) colloids synthesized in deionized water by laser ablation of solids in liquids technique (LASL) were oxidized using NaClO solutions at different concentrations. Oxidized nanomaterials were characterized using several techniques. The crystalline phases of the bismuth compound were determined using Raman microspectroscopy, and the crystallographic structure was identified by x-ray diffraction (XRD). The size and morphology of the obtained nanomaterials were studied by transmission electron microscopy (TEM). The chemical states were determined using x-ray photoelectron spectroscopy (XPS), and the optical properties of the colloids were characterized by UV-vis spectroscopy. The absorption spectra were analyzed using the Tauc method to determine the band gaps of the obtained nanomaterials. Our results showed morphological changes, starting from small nanoparticles to nanosheets and a mixture of nanosheets with hollow nanoparticles. Two kinds of nanomaterials were found depending on the NaClO solution concentration: Bi₂O₂CO₃single phase and a mixture ofδ-Bi₂O₃and Bi₂O₂CO₃. Some samples were tested as photocatalysts and showed good performance in the degradation of methylene blue in solution. To the best of our knowledge, this is the first study on the oxidation process of bismuth colloidal nanoparticles at room temperature.

Biofilm response and removal via the coupling of visible-light-driven photocatalysis and biodegradation in an environment of sulfamethoxazole and Cr(VI)

The widespread contamination of water systems with antibiotics and heavy metals has gained much attention. Intimately coupled visible -light-responsive photocatalysis and biodegradation (ICPB) provides a novel approach for removing such mixed pollutants. In ICPB, the photocatalysis products are biodegraded by a protected biofilm, leading to the mineralization of refractory organics. In the present study, the ICPB approach exhibited excellent photocatalytic activity and biodegradation, providing up to ∼1.27 times the degradation rate of sulfamethoxazole (SMX) and 1.16 times the Cr(VI) reduction rate of visible-light-induced photocatalysis . Three-dimensional fluorescence analysis demonstrated the synergistic ICPB effects of photocatalysis and biodegradation for removing SMX and reducing Cr(VI). In addition, the toxicity of the SMX intermediates and Cr(VI) in the ICPB process significantly decreased. The use of MoS₂/CoS₂ photocatalyst accelerated the separation of electrons and holes, with•O₂^- and h⁺ attacking SMX and e^- reducing Cr(VI), providing an effective means for enhancing the removal and mineralization of these mixed pollutants via the ICPB technique. The microbial community results demonstrate that bacteria that are conducive to pollutant removal are were enriched by the acclimation and ICPB operation processes, thus significantly improving the performance of the ICPB system.

Synthesis of "Naked" TeO2 Nanoparticles for Biomedical Applications

Chalcogenide nanoparticles have become a very active field of research for their optoelectronic and biological properties. This article shows the production of tellurium dioxide nanoparticles (TeO2 NPs) by pulsed laser ablation in liquids. The produced nanoparticles were spherical with a diameter of around 70 nm. The energy band gap of those nanoparticles was determined to be around 5.2 eV. Moreover, TeO2 NPs displayed a dose-dependent antibacterial effect against antibiotic-resistant bacteria such as multidrug-resistant Escherichia coli (MDR E. coli) and methicillin-resistant Staphylococcus aureus (MR S. aureus). The "naked" nature of the nanoparticle surface helped to eradicate the antibiotic-resistant bacteria at a very low concentration, with IC50 values of ∼4.3 ± 0.9 and 3.7 ± 0.2 ppm for MDR E. coli and MR S. aureus, respectively, after just 8 h of culture. Further, the IC50 values of the naked TeO2 NPs against melanoma (skin cancer) and healthy fibroblasts were 1.6 ± 0.7 and 5.5 ± 0.2 ppm, respectively, for up to 72 h. Finally, to understand these optimal antibacterial and anticancer properties of the TeO2 NPs, the reactive oxygen species generated by the nanoparticles were measured. In summary, the present in vitro results demonstrate much promise for the presently prepared TeO2 NPs and they should be studied for a wide range of safe antibacterial and anticancer applications.

Degradation of formaldehyde aqueous solution by Bi based catalyst and its activity evaluation

Bi based catalysts have attracted continuous attention from the scientific community because of their excellent photochemical properties and wide application in photocatalytic treatment of environmental pollution. A series of Bi based catalysts with good crystallinity and high purity were prepared by calcination and hydrothermal synthesis. In the application of degrading formaldehyde aqueous solution in a mercury lamp and xenon lamp atmosphere, it was found that BiVO4 and Bi2WO6 showed excellent photochemical properties under ultraviolet and visible light. The tests of PL, UV-Vis and EIS confirmed their high activity. In the calculation based on density functional theory (DFT), through the analysis of the energy band structure, density of states (DOS) and partial wave density of states (PDOS), it is found that the d orbital of V and W elements has a great influence on the position and size of the energy band of the catalyst, which makes it have high activity and excellent electrochemical properties.