Bacteria growing in biofilms cause a wide range of environmental, industrial and public health risks. Because biofilm bacteria are very resistant to antibiotics, there is an urgent need in medicine and industry to develop new approaches to eliminating bacterial biofilms. One strategy for controlling these biofilms is to generate an antibiofilm substance locally at the attachment surface. Direct electric current (DC) and nanoparticles (NPs) of metal oxides have outstanding antimicrobial properties. In this study we evaluated the effect of titanium oxide nanoparticle (TiO$_2$-NP) concentrations from 5 to 160 $\mu$g/mL on Bacillus cereus and Pseudomonas aeruginosa biofilms, and compared this with the effect of a 9 V, 6 mA DC electric field for 5, 10 and 15 min. TiO$_2$-NPs were characterized using transmission and scanning electron microscopes, X-ray diffraction and FTIR. They exhibited an average size of 22-34 nm. The TiO$_2$-NP concentrations that attained LD50 were $104 \pm 4$ $\mu$g/mL and $63 \pm 3$ $\mu$g/mL for B. cereus and P. aeruginosa, respectively. The eradication percentages obtained by DC at 5, 10, and 15 min exposure were 21%, 29%, and 33% respectively for B. cereus and 30%, 39%, and 44% respectively for P. aeruginosa. Biofilm disintegration was verified by exopolysaccharide, protein content and cell surface hydrophobicity assessment, as well as scanning electron microscopy. These data were correlated with the reactive oxygen species produced. The results indicated that both DC and TiO$_2$-NPs have a lethal effect on these bacterial biofilms, and that the DC conditions used affect the biofilms in a similar way to TiO$_2$-NPs at concentrations of 20-40 $\mu$g/mL.

Impaired wound healing is a common complication of diabetes mellitus. Nanofibre can be served as powerful tools in advanced wound care management. The aim of this work is to evaluate the role of antibacterial nanofibres by incorporating silver nanoparticles into celluose acetate nanofibres as wound dressing on excisional wound healing in diabetic mice. Celluose acetate nanofibres were prepared by electrospinning technique. The prepared nanofibres were characterised using scanning electron microscope (SEM), and Fourier-transform infrared (FTIR) spectrophotometer. The antimicrobial activity was tested against Gram-positive and Gram-negative bacteria. A full thickness of the excision wound of circular area 95 mm 2 and 2 mm depth was created. Wound dressed by silver containing nanofibres, the wound closure rate were assessed, skin wounds were processed for histopathological examination Preparation and characterisation of antibacterial 83and comparing the mechanical properties of healed skin. It was found that, wounds dressed with silver containing nanofibres showed marked increase in collagen production which improve the skin mechanical properties.

Background: The re-emergence of infectious diseases and the increasing rate of the appearance of many antibiotic-resistant strains are major public health concerns. Zinc oxide nanoparticles (ZnO-NPs) have a great antibacterial effect. Few reports stated the antibacterial effect of low electric field (LEF). Objective: The paper aimed to study the antibacterial effect of LEF at low frequency and investigate the antibacterial effectiveness of using LEF in synergy with ZnO-NPs. Methods: Pseudomonas aeruginosa and Staphylococcus aureus were examined as models for Gram-negative and Gram-positive bacteria, respectively. The bacterial suspension was exposed to different concentrations of Zn-NPs ranging from 100-1600 µg/ml or 2 V/cm, 500 Hz AC electric field for 5 min. ZnO-NPs were prepared and characterized by UV-Vis spectroscopy, XRD, FTIR, TEM, and SEM. The combined effect of LEF exposure with each ZnO-NPs concentration was assessed. Results: 1600 µg/ml ZnO-NPs cause 41.93% and 48.15% death, LEF produces 20.88% and 28.03% death, and the synergetic effect causes 50.41% and 70.27% death for P. aeruginosa and S. aureus, respectively. The death percentages were correlated with DNA concentration and deformation, reactive oxygen species concentration, and ultrastructure changes. Conclusions: LEF has antibacterial properties and can be used in combination with ZnO-NPs to increase its lethal effect.

ABSTRACT

Cancer remains a leading cause of death worldwide, despite extraordinary progress. So, new cancer treatment modalities are needed. Tumor-treating fields (TTFs) use low-intensity, intermediate-frequency alternating electric fields with reported cancer anti-mitotic properties. Moreover, nanomedicine is a promising therapy option for cancer. Numerous cancer types have been treated with nanoparticles, but zinc oxide nanoparticles (ZnO NPs) exhibit biocompatibility. Here, we investigate the activity of TTFs, a sub-lethal dose of ZnO NPs, and their combination on hepatocellular carcinoma (HepG2), the colorectal cancer cell line (HT-29), and breast cancer cell lines (MCF-7). The lethal effect of different ZnO NPs concentrations was assessed by sulforhodamine B sodium salt assay (SRB). The cell death percent was determined by flow cytometer, the genotoxicity was evaluated by comet assay, and the total antioxidant capacity was chemically measured. Our results show that TTFs alone cause cell death of 14, 8, and 17% of HepG2, HT-29, and MCF-7, respectively; 10 µg/mL ZnO NPs was the sub-lethal dose according to SRB results. The combination between TTFs and sub-lethal ZnO NPs increased the cell death to 29, 20, and 33% for HepG2, HT-29, and MCF-7, respectively, without reactive oxygen species increase. Increasing NPs potency using TTFs can be a novel technique in many biomedical applications.