Targeted and effective therapy of diseases demands utilization of rapid methods of identification of the given markers. Surface enhanced Raman spectroscopy (SERS) in conjunction with streptavidin-biotin complex is a promising alternative to culture or PCR based methods used for such purposes. Many biotinylated antibodies are available on the market and so this system offers a powerful tool for many analytical applications. Here, we present a very fast and easy-to-use procedure for preparation of streptavidin coated magnetic polystyrene-Au (or Ag) nanocomposite particles as efficient substrate for surface SERS purposes. As a precursor for the preparation of SERS active and magnetically separable composite, commercially available streptavidin coated polystyrene (PS) microparticles with a magnetic core were utilized. These composites of PS particles with silver or gold nanoparticles were prepared by reducing Au(III) or Ag(I) ions using ascorbic acid or dopamine. The choice of the reducing agent influences the morphology and the size of the prepared Ag or Au particles (15-100 nm). The prepare composites were also characterized by HR-TEM images, mapping of elements and also magnetization measurements. The content of Au and Ag was determined by AAS analysis. The synthesized composites have a significantly lower density against magnetic composites based on iron oxides, which considerably decreases the tendency to sedimentation. The polystyrene shell on a magnetic iron oxide core also pronouncedly reduces the inclination to particle aggregation. Moreover, the preparation and purification of this SERS substrate takes only a few minutes. The PS composite with thorny Au particles with the size of approximately 100 nm prepared was utilized for specific and selective detection of Staphylococcus aureus infection in joint knee fluid (PJI) and tau protein (marker for Alzheimer disease).

• MeSH
• Alzheimer Disease blood   diagnosis   genetics   MeSH
• Biomarkers analysis   MeSH
• Dopamine chemistry   MeSH
• Ascorbic Acid chemistry   MeSH
• Humans MeSH
• Magnetic Iron Oxide Nanoparticles chemistry   ultrastructure   MeSH
• Polystyrenes chemistry   MeSH
• tau Proteins analysis   blood   genetics   MeSH
• Spectrum Analysis, Raman methods   MeSH
• Staphylococcal Infections diagnosis   microbiology   MeSH
• Staphylococcus aureus growth & development   pathogenicity   MeSH
• Streptavidin chemistry   MeSH
• Silver chemistry   MeSH
• Synovial Fluid microbiology   MeSH
• Particle Size MeSH
• Gold chemistry   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Names of Substances
• Biomarkers MeSH
• Dopamine MeSH
• Ascorbic Acid MeSH
• MAPT protein, human MeSH Browser
• Polystyrenes MeSH
• tau Proteins MeSH
• Streptavidin MeSH
• Silver MeSH
• Gold MeSH

PURPOSE: The aim was to design and thoroughly characterize monodisperse Fe3O4@SiO2-Ag nanoparticles with strong antibacterial properties, which makes them a candidate for targeting bacterial infections. METHODS: The monodisperse Fe3O4 nanoparticles were prepared by oleic acid-stabilized thermal decomposition of Fe(III) oleate; the particles were coated with silica shell using a water-in-oil reverse microemulsion, involving hydrolysis and condensation of tetramethyl orthosilicate. Resulting Fe3O4@SiO2 particles were modified by (3-mercaptopropyl)trimethoxysilane to introduce 1.1 mmol SH/g. Finally, the Fe3O4@SiO2-SH nanoparticles were decorated with silver nanoclusters formed by reduction of silver nitrate with NaBH4. The particles were analyzed by FTIR, X-ray photoelectron and atomic absorption spectroscopy, dynamic light scattering and vibrating sample magnetometry. The antibacterial activity of the Fe3O4@SiO2 and Fe3O4@SiO2-Ag nanoparticles was tested against Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria cultivated on Luria agar plates or in Luria broth. RESULTS: The superparamagnetic Fe3O4@SiO2-Ag nanoparticles (21 nm in diameter; saturation magnetization 26 A∙m2/kg) were successfully obtained and characterized. Inhibitory and toxic effects against bacteria were documented by incubation of the Fe3O4@SiO2-Ag nanoparticles with Staphylococcus aureus and Escherichia coli. CONCLUSIONS: The combination of magnetic properties together with bactericidal effects is suitable for the disinfection of medical instruments, water purification, food packaging, etc.

• Keywords
• antibacterial activity, magnetic nanoparticles, silica shell, thiol-functionalization,
• MeSH
• Anti-Bacterial Agents chemistry   pharmacology   MeSH
• Escherichia coli drug effects   MeSH
• Oleic Acid chemistry   MeSH
• Magnetite Nanoparticles chemistry   MeSH
• Organosilicon Compounds MeSH
• Silicon Dioxide chemistry   MeSH
• Surface Properties MeSH
• Silanes chemistry   MeSH
• Staphylococcus aureus drug effects   MeSH
• Silver chemistry   pharmacology   MeSH
• Particle Size MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• (3-mercaptopropyl)trimethoxysilane MeSH Browser
• Anti-Bacterial Agents MeSH
• Oleic Acid MeSH
• Magnetite Nanoparticles MeSH
• Organosilicon Compounds MeSH
• Silicon Dioxide MeSH
• Silanes MeSH
• Silver MeSH

Despite the extensive research, the mechanism of the antimicrobial and biocidal performance of silver nanoparticles has not been unequivocally elucidated yet. Our study was aimed at the investigation of the ability of silver nanoparticles to suppress the growth of three types of algae colonizing the wetted surfaces or submerged objects and the mechanism of their action. Silver nanoparticles exhibited a substantial toxicity towards Chlorococcales Scenedesmus quadricauda, Chlorella vulgaris, and filamentous algae Klebsormidium sp., which correlated with their particle size. The particles had very good stability against agglomeration even in the presence of multivalent cations. The concentration of silver ions in equilibrium with nanoparticles markedly depended on the particle size, achieving about 6 % and as low as about 0.1 % or even less for the particles 5 nm in size and for larger ones (40-70 nm), respectively. Even very limited proportion of small particles together with larger ones could substantially increase concentration of Ag ions in solution. The highest toxicity was found for the 5-nm-sized particles, being the smallest ones in this study. Their toxicity was even higher than that of silver ions at the same silver concentration. When compared as a function of the Ag(+) concentration in equilibrium with 5-nm particles, the toxicity of ions was at least 17 times higher than that obtained by dissolving silver nitrite (if not taking into account the effect of nanoparticles themselves). The mechanism of the toxicity of silver nanoparticles was found complex with an important role played by the adsorption of silver nanoparticles and the ions released from the particles on the cell surface. This mechanism could be described as some sort of synergy between nanoparticles and ions. While our study clearly showed the presence of this synergy, its detailed explanation is experimentally highly demanding, requiring a close cooperation between materials scientists, physical chemists, and biologists.

• Keywords
• Algae, Concentration of silver ions in equilibrium with silver nanoparticles, Silver ions, Silver nanoparticles, Toxicity, Uptake of silver by algae,
• MeSH
• Anti-Infective Agents metabolism   toxicity   MeSH
• Chlorella vulgaris drug effects   metabolism   MeSH
• Ions metabolism   MeSH
• Metal Nanoparticles toxicity   MeSH
• Solutions MeSH
• Scenedesmus drug effects   metabolism   MeSH
• Silver metabolism   toxicity   MeSH
• Toxicity Tests MeSH
• Particle Size MeSH
• Publication type
• Journal Article MeSH
• Names of Substances
• Anti-Infective Agents MeSH
• Ions MeSH
• Solutions MeSH
• Silver MeSH

It is expected that the projected increased usage of implantable devices in medicine will result in a natural rise in the number of infections related to these cases. Some patients are unable to autonomously prevent formation of biofilm on implant surfaces. Suppression of the local peri-implant immune response is an important contributory factor. Substantial avascular scar tissue encountered during revision joint replacement surgery places these cases at an especially high risk of periprosthetic joint infection. A critical pathogenic event in the process of biofilm formation is bacterial adhesion. Prevention of biomaterial-associated infections should be concurrently focused on at least two targets: inhibition of biofilm formation and minimizing local immune response suppression. Current knowledge of antimicrobial surface treatments suitable for prevention of prosthetic joint infection is reviewed. Several surface treatment modalities have been proposed. Minimizing bacterial adhesion, biofilm formation inhibition, and bactericidal approaches are discussed. The ultimate anti-infective surface should be "smart" and responsive to even the lowest bacterial load. While research in this field is promising, there appears to be a great discrepancy between proposed and clinically implemented strategies, and there is urgent need for translational science focusing on this topic.

• MeSH
• Anti-Bacterial Agents pharmacology   therapeutic use   MeSH
• Bacteria drug effects   MeSH
• Coated Materials, Biocompatible pharmacology   therapeutic use   MeSH
• Prosthesis-Related Infections prevention & control   MeSH
• Humans MeSH
• Orthopedics MeSH
• Surface Properties MeSH
• Prostheses and Implants MeSH
• Check Tag
• Humans MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Review MeSH
• Names of Substances
• Anti-Bacterial Agents MeSH
• Coated Materials, Biocompatible MeSH

Due to the rapid development of industry and associated production of toxic waste, especially heavy metals, there is a great interest in creating and upgrading new sorption materials to remove these pollutants from the environment. This study aims to determine the effectiveness of different carbon forms (graphene, expanded carbon, multi-wall nanotubes) and paramagnetic particles (Fe₂O₃) for adsorption of cadmium(II), lead(II), and copper(II) on its surface, with different interaction time from 1 min to 24 h. The main attention is paid to the detection of these metals using differential pulse voltammetry. Based on the obtained results, graphene and Fe₂O₃ are found to be good candidates for removal of heavy metals from the environment.

• Keywords
• electrochemical detection, expanded carbon, graphene, heavy metal ions, multi-wall nanotubes, paramagnetic particle, voltammetry,
• Publication type
• Journal Article MeSH