silicon and Bacterial-Infections

Topics: Animals; Anti-Bacterial Agents; Antifungal Agents; Anura; Bacterial Infections; Cardiovascular System; Chemical Phenomena; Chemistry; Fungi; Growth; Halogens; Humans; Infections; Insect Repellents; Insecticides; Lethal Dose 50; Metabolism; Mice; Nervous System; Nitrogen; Plants; Rabbits; Radiation-Protective Agents; Rats; Silicon; Silicones; Silicosis; Ultraviolet Rays

'Black silicon' (bSi) samples with surfaces covered in nanoneedles of varying length, areal density and sharpness, have been fabricated using a plasma etching process. These nanostructures were then coated with a conformal uniform layer of diamond using hot filament chemical vapour deposition to produce 'black diamond' (bD) surfaces. The effectiveness of these bSi and bD surfaces in killing Gram-negative (E. coli) and Gram-positive (S. gordonii) bacteria was investigated by culturing the bacteria on the surfaces for a set time and then measuring the live-to-dead ratio. All the nanostructured surfaces killed E. coli at a significantly higher rate than the respective flat Si or diamond control samples. The length of the needles was found to be less important than their separation, i.e. areal density. This is consistent with a model for mechanical bacteria death based on the stretching and disruption of the cell membrane, enhanced by the cells motility on the surfaces. In contrast, S. gordonii were unaffected by the nanostructured surfaces, possibly due to their smaller size, thicker cell membrane and/or their lack of motility.

Topics: Anti-Bacterial Agents; Bacterial Infections; Biocompatible Materials; Boron Compounds; Diamond; Escherichia coli; Humans; Nanostructures; Silicon; Streptococcus gordonii; Surface Properties

In order to address the issue of pathogenic bacterial colonization of diabetic wounds, a more direct and robust approach is required, which relies on a physical form of bacterial destruction in addition to the conventional biochemical approach (i.e., antibiotics). Targeted bacterial destruction through the use of photothermally active nanomaterials has recently come into the spotlight as a viable approach to solving the rising problem of antibiotic resistant microorganisms. Materials with high absorption coefficients in the near-infrared (NIR) region of the electromagnetic spectrum show promise as alternative antibacterial therapeutic agents, since they preclude the development of bacterial resistance and can be activated on demand. Here were report on a novel approach for the fabrication of gold nanoparticle decorated porous silicon nanopillars with tunable geometry that demonstrate excellent photothermal conversion properties when irradiated with a 808 nm laser. These photothermal antibacterial properties are demonstrated in vitro against the Gram-positive bacteria Staphylococcus aureus (S. aureus) and Gram-negative Escherichia coli (E. coli). Results show a reduction in bacterial viability of up to 99% after 10 min of laser irradiation. We also show an increase in antibacterial performance after modifying the nanopillars with S. aureus targeting antibodies causing up to a 10-fold increase in bactericidal efficiency compared to E. coli. In contrast, the nanomaterial resulted in minimal disruption of metabolic processes in human foreskin fibroblasts (HFF) after an equivalent period of irradiation.

Topics: Anti-Bacterial Agents; Bacterial Infections; Escherichia coli; Gold; Humans; Metal Nanoparticles; Microbial Sensitivity Tests; Nanostructures; Porosity; Silicon; Staphylococcus aureus

Polymeric materials are commonly found in orthopedic implants due to their unique mechanical properties and biocompatibility but the poor surface hardness and bacterial infection hamper many biomedical applications. In this study, a ceramic-like surface structure doped with silver is produced by successive plasma implantation of silicon (Si) and silver (Ag) into the polyamine 66 (PA66) substrate. Not only the surface hardness and elastic modulus are greatly enhanced due to the partial surface carbonization and the ceramic-like structure produced by the reaction between energetic Si and the carbon chain of PA66, but also the antibacterial activity is improved because of the combined effects rendered by Ag and SiC structure. Furthermore, the modified materials which exhibit good cytocompatibility upregulate bone-related genes and proteins expressions of the contacted bone mesenchymal stem cells (BMSCs). For the first time, it explores out that BMSCs osteogenesis on the antibacterial ceramic-like structure is mediated via the iNOS and nNOS signal pathways. The results reveal that in situ plasma fabrication of an antibacterial ceramic-like structure can endow PA66 with excellent surface hardness, cytocompatibility, as well as antibacterial capability.

Topics: Animals; Anti-Bacterial Agents; Bacteria; Bacterial Infections; Biocompatible Materials; Bone and Bones; Cell Line; Ceramics; Elastic Modulus; Hardness; Humans; Materials Testing; Mesenchymal Stem Cells; Mice; Osteogenesis; Polyamines; Polymers; Prostheses and Implants; Silicon; Silver; Surface Properties

Protection by ear plugs from water-borne infection was evaluated in 35 patients with "tympanostomy" tubes, tympanic membrane perforations, or mastoid bowls. Stock and custom-made ear plugs were found to be equally effective up to four months during a period of frequent swimming and bathing activities. Infections were only noted to occur in those patients who did not follow instructions on appropriate use of the plugs.

Topics: Adolescent; Adult; Bacterial Infections; Child; Child, Preschool; Ear Protective Devices; Ear, Middle; Evaluation Studies as Topic; Female; Humans; Male; Protective Devices; Silicon; Swimming; Tympanic Membrane; Water