Background: Bismuth compounds are known for their activity against multiple microorganisms; yet, the antibiotic properties of bismuth nanoparticles (BiNPs) remain poorly explored. The objective of this work is to further the research of BiNPs for nanomedicine-related applications. Stable Polyvinylpyrrolidone (PVP)-coated BiNPs were produced by a chemical reduction process, in less than 30 min. Results: We produced stable, small, spheroid PVP-coated BiNPs with a crystalline organization. The PVP-BiNPs showed potent antibacterial activity against the pathogenic bacterium Staphylococcus aureus and antifungal activity against the opportunistic pathogenic yeast Candida albicans, both under planktonic and biofilm growing conditions. Conclusions: Our results indicate that BiNPs represent promising antimicrobial nanomaterials, and this facile synthetic method may allow for further investigation of their activity against a variety of pathogenic microorganisms.

Early Mortality Syndrome (EMS) or Acute Hepatopancreatic Necrosis Syndrome (AHPNS) is a disease produced by gram-negative bacteria Vibrio parahaemolyticus (V. parahaemolyticus), which has caused declines in worldwide production of a white shrimp Litopenaeus vannamei (L. vannamei). In this work, we propose the implementation of silver nanoparticles (AgNPs) synthesized with Rumex hymenosepalus (Rh) extract as an alternative on V. parahaemolyticus control. AgNPs were characterized by UV-Vis spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and selected area electron diffraction (SAED). AgNP mean sizes by DLS were 80.82±1.16nm and sizes between 2 and 10 nm by TEM, with a zeta potential of −47.72±1.05mV. This study evaluated AgNPs and Rh antimicrobial capacity on V. parahaemolyticus at different concentrations; the minimum inhibitory concentration (MIC) found was 25 μg/mL for AgNPs and 220 μg/mL for Rh. Additionally, were carried out time-kill curves and reactive oxygen species (ROS) generation for 1 and 4 MIC. Both concentrations (MIC) were tested for toxicity on Artemia nauplii from Artemia franciscana (A. franciscana), because nauplii were used as biocarriers for AgNPs and Rh extract on L. vannamei. Once the shrimp were treated, they were challenged with Vibrio infection and it was found that those who were treated with both agents showed greater survival than the control. V. parahaemolyticus and postlarval samples were taken from the bioassay and fixed and prepared for TEM and SEM in order to search NPs in internal structure of bacteria and the hepatopancreatic area of shrimps; AgNPs were detected in both cases. AgNPs and Rh extract show antibacterial properties on the infected shrimp with V. parahaemolyticus. The action mechanisms are interaction with the bacterial membrane and ROS generation; these effects are produced by both agents.

This study investigates the performance of thin film Ga₂O₃‐based fin field‐effect transistors (FinFETs) built on patterned silicon substrates. The Ga₂O₃ thin film is deposited using trimethylgallium (TMGa) ALD processes. Three devices are fabricated: one utilizing as‐deposited thin film materials, another subjected to post‐deposition annealing at 450°C, and a third annealed at 900°C. The electrical, optical, and material properties of the thin films and transistor devices are evaluated using a range of complementary characterization techniques, whilst the effects of post‐deposition annealing at moderate (450°C) and higher temperature (900°C) are also investigated. The as‐deposited device exhibited an Ion/Ioff ratio of 8.8 × 10⁶, an Ion density of 0.062 µA.µm⁻², a maximum charge carrier mobility of 3.2 cm2.V⁻¹s⁻¹, a threshold voltage (Vth) of 7.9 V, a sub‐threshold swing (SS) of 590 mV.dec⁻¹, and a breakdown voltage (BVDSS) of 40 V. After annealing in N₂ atmosphere, the device annealed at 450°C displayed significant improvements, with an Ion/Ioff ratio of 8.3 × 107, Ion density of 0.14 µA.µm⁻², a maximum charge carrier mobility of 8.5 cm2.V⁻¹s⁻¹, Vth of 8.5 V, SS of 475 mV.dec⁻¹, and a remarkable BVDSS exceeding 200 V. In contrast, the 900°C annealed sample exhibited a decrease in performance, with an Ion/Ioff ratio of 1.2 × 107, Ion density of 0.023 µA.µm⁻², mobility dropping to 1.4 cm₂.V⁻¹s⁻¹, Vth of 9.2 V, and SS of 510 mV.dec⁻¹, although it maintained a breakdown voltage above 200 V. The surface morphology and materials compositions of the fabricated devices are further analyzed via a combination of scanning electron and transmission electron microscopy techniques. The obtained results confirmed a significant material transition from amorphous phase in as‐deposited films into polycrystalline morphologies with noticeable grain boundaries for samples with thermal annealing.

Bismuth compounds are known for their activity against multiple microorganisms; yet, the antibiotic properties of bismuth nanoparticles (BiNPs) remain poorly explored. The objective of this work is to further the research of BiNPs for nanomedicine, particularly as a disinfectant and for future treatments. Stable PVP-coated BiNPs were produced by a chemical reduction process, in less than 30 minutes, in a heated alkaline glycine solution, by the chelation and reduction of the bismuth (III) ion; resulting in the generation of small, spheroid particles with a crystalline organization. We assessed the antibacterial and antifungal activity of bismuth nanoparticles. PVP-BiNPs showed potent antibacterial activity against the pathogenic bacterium Staphylococcus aureus and antifungal activity against the opportunistic pathogenic yeast Candida albicans , both under planktonic and biofilm growing conditions. Our results indicate that BiNPs represent promising antimicrobial nanomaterials, and this facile synthetic method may allow for further investigation of their activity against a variety of pathogenic microorganisms.

Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.