silicon and Staphylococcal-Infections

The increasing problem of bacterial resistance to the currently effective antibiotics has resulted in the need for increasingly potent therapeutics to eradicate pathogenic microorganisms. 2D nanomaterials (2D NMs) have unique physical and chemical properties that make them attractive candidates for biomedical applications. Recently, the application of 2D NMs as antibacterial agents has attracted significant attention. Herein, a novel 2D graphene-like silicon nanosheet (GS NS) antimicrobial agent is fabricated from pristine silicon crystals by ultrasonication, which results in a highly exfoliated planar morphology and a significantly larger surface area as compared with bulk silicon. The GS NSs exhibit remarkable in vitro broad-spectrum bactericidal activity against Gram (-) Escherichia coli and Gram (+) Staphylococcus aureus because of a close interaction with the bacteria, which leads to highly efficient membrane destruction. The in vivo studies demonstrate that the local administration of GS NSs effectively mitigates implant-related infection by reducing the bacterial burden of the extracted samples and accelerating the remission of local inflammation. Based on these encouraging results, GS NSs are expected to be a useful new member of the 2D NMs family, with the potential of effectively killing pathogenic bacteria in clinical applications.

Topics: Animals; Anti-Bacterial Agents; Bacterial Load; Cell Membrane; Dose-Response Relationship, Drug; Escherichia coli; Graphite; L-Lactate Dehydrogenase; Mice, Inbred BALB C; Microbial Sensitivity Tests; Microscopy, Electron, Transmission; Nanostructures; Prosthesis-Related Infections; Silicon; Staphylococcal Infections; Staphylococcus aureus

Prevention of infection and enhanced osseointegration are closely related, and required for a successful orthopaedic implant, which necessitate implant designs to consider both criteria in tandem. A multi-material coating containing 1:1 ratio of silicon-substituted hydroxyapatite and silver-substituted hydroxyapatite as the top functional layer, and hydroxyapatite as the base layer, was produced via the drop-on-demand micro-dispensing technique, as a strategic approach in the fight against infection along with the promotion of bone tissue regeneration. The homogeneous distribution of silicon-substituted hydroxyapatite and silver-substituted hydroxyapatite micro-droplets at alternate position in silicon-substituted hydroxyapatite-silver-substituted hydroxyapatite/hydroxyapatite coating delayed the exponential growth of Staphylococcus aureus for up to 24 h, and gave rise to up-regulated expression of alkaline phosphatase activity, type I collagen and osteocalcin as compared to hydroxyapatite and silver-substituted hydroxyapatite coatings. Despite containing reduced amounts of silicon-substituted hydroxyapatite and silver-substituted hydroxyapatite micro-droplets over the coated area than silicon-substituted hydroxyapatite and silver-substituted hydroxyapatite coatings, silicon-substituted hydroxyapatite-silver-substituted hydroxyapatite/hydroxyapatite coating exhibited effective antibacterial property with enhanced bioactivity. By exhibiting good controllability of distributing silicon-substituted hydroxyapatite, silver-substituted hydroxyapatite and hydroxyapatite micro-droplets, it was demonstrated that drop-on-demand micro-dispensing technique was capable in harnessing the advantages of silver-substituted hydroxyapatite, silicon-substituted hydroxyapatite and hydroxyapatite to produce a multi-material coating along with enhanced bioactivity and reduced infection.

Topics: Adipocytes; Alkaline Phosphatase; Anti-Bacterial Agents; Apatites; Bone Regeneration; Cell Proliferation; Coated Materials, Biocompatible; Collagen; Humans; Hydroxyapatites; Metal Nanoparticles; Microbial Sensitivity Tests; Microscopy, Confocal; Osseointegration; Osteocalcin; Powders; Silicon; Silver; Staphylococcal Infections; Staphylococcus aureus; Surface Properties

Protein A, which is secreted by and displayed on the cell membrane of Staphylococcus aureus is an important biomarker for S. aureus. Thus, its rapid and specific detection may facilitate the pathogen identification and initiation of proper treatment. Herein, we present a simple, label-free and rapid optical biosensor enabling specific detection of protein A. Protein A-binding aptamer serves as the capture probe and is immobilized onto a nanostructured porous silicon thin film, which serves as the optical transducer element. We demonstrate high sensitivity of the biosensor with a linear detection range between 8 and 23μM. The apparent dissociation constant was determined as 13.98μM and the LoD is 3.17μM. Harnessing the affinity between protein A and antibodies, a sandwich assay format was developed to amplify the optical signal associated with protein A capture by the aptamer. Using this approach, we increase the sensitivity of the biosensor, resulting in a three times lower LoD.

Topics: Antibodies; Aptamers, Nucleotide; Biosensing Techniques; Immobilization; Immunoglobulin G; Nanostructures; Optical Phenomena; Porosity; Sensitivity and Specificity; Silicon; Staphylococcal Infections; Staphylococcal Protein A; Staphylococcus aureus

This article describes a simple and inexpensive signal amplification method, termed polymeric enzyme detection (PED), which permits rapid and sensitive detection of conserved sequences in the tuf gene that identify Staphylococcus genus, conserved sequences in the femB gene that specifically detect Staphylococcus aureus species, and the methicillin resistance gene mecA directly from positive blood culture bottles. Microbe-specific capture probes were immobilized onto microtiter plates or silicon chips. Target sequences and biotin-labeled, target-specific probes were hybridized to complementary capture probes to create a biotin-labeled, surface-immobilized tripartite complex. In a two-step process, signal was amplified by incubating the surface-immobilized biotin with streptavidin followed by the addition of a 500-kDa dextran polymer conjugated with approximately 80 biotins. Signal was then developed by binding of a streptavidin-horseradish peroxidase conjugate followed by incubation with the substrate tetramethylbenzidine. Use of the PED method improved the lower limit of detection 10- to 100-fold in model DNA hybridization assays with limits of detection as low as 1 fmol/L target DNA. This level of sensitivity permits detection of genomic DNA from methicillin-resistant S. aureus positive blood cultures within 25 to 35 min using either a thin film biosensor chip or a microtiter plate-based assay.

Topics: Bacteremia; Bacterial Proteins; Biosensing Techniques; Biotin; Genome, Bacterial; Horseradish Peroxidase; Humans; Limit of Detection; Methicillin-Resistant Staphylococcus aureus; Nucleic Acid Hybridization; Oligonucleotide Probes; Silicon; Staphylococcal Infections; Staphylococcus

Ion beam-based processes such as ion implantation (silicone rubber) and ion beam-assisted deposition (silver-based coatings) affect the outer micron layers of catheter surfaces. These processes were used on the common catheter materials of silicone and polyurethane. In 56 rats, surface (Spi-Silicone and Spi-Argent I and II) catheter segments were implanted for 1, 3, and 6 weeks. After removal, these pieces were investigated for bacterial colonization and fixed for scanning electron microscopic evaluation. As controls, untreated catheter segments were implanted in 28 rats. Bacterial colonization was found in 2.4% in the surface treated catheter pieces versus 7.1% in the control group. The scanning electron microscope investigations showed low thrombogenicity in all of the treated catheters independent of the implantation times.

Topics: Animals; Biocompatible Materials; Catheters, Indwelling; Microscopy, Electron; Rats; Rubber; Silicon; Silver; Staphylococcal Infections; Surface Properties; Thrombosis

Topics: Ciprofloxacin; Female; Humans; Middle Aged; Nose Diseases; Prostheses and Implants; Prosthesis-Related Infections; Rhinoplasty; Silicon; Staphylococcal Infections

Topics: Catheters, Indwelling; Humans; Sepsis; Silicon; Staphylococcal Infections