Ultra-Small Gold Nanoparticles with Mild Immunomodulatory Activity as a Potential Tool for Bio-Applications.

Recently, more and more efforts are directed towards developing new imaging and drug-delivery options based on various nanoparticles, exploiting their unique properties. Here, ultra-small gold nanoparticles functionalized with widely used polyethylene glycol and its amine-terminated form were tested in respect of their potential interactions with human immune cells (cell line and primary cells). The results showed that differently terminated ultrasmall gold nanoparticles represent an interesting theranostic platform as they are harmless to immune cells (not inducing cytotoxicity and severe immune response) and on the other hand, they can serve as imaging and/or drug delivery agents using e.g. monocytes/ macrophages as "Trojan horses" to deliver these nanoparticles across the blood-brain barrier and diagnose or treat pathologies of the central nervous system.

Gold, Silver and Carbon Nanoparticles Grafted on Activated Polymers for Biomedical Applications.

Organic polymers have been applied successfully in fields such as adhesion, biomaterials, protective coatings, friction and wear, composites, microelectronic devices, and thin-film technology. In general, special surface properties with regard to chemical composition, hydrophilicity, roughness, crystallinity, conductivity, lubricity, and cross-linking density are required for the success of these applications. Polymers very often do not possess the surface properties needed for these applications. For these reasons, surface modification techniques which can transform these inexpensive materials into highly valuable finished products have become an important part of the plastics industry. In case of biomedical polymers is plasma treatment used for enhancing cell adhesion, growth and proliferation and to make them suitable for implants and tissue engineering scaffolds. Nanoparticles fascinated scientists for over a century and are now heavily utilized in chemistry, biology, engineering, and medicine. Nowadays nanoparticles can be synthesized reproducibly, modified with seemingly limitless chemical functional groups, and, in certain cases, characterized with atomic-level precision. In recent years, focus has turned to therapeutic possibilities for such materials. Structures, which behave as drug carriers, antimicrobial agents, and photoresponsive therapeutics have been developed and studied in the context of cells and many debilitating diseases. These structures are not simply chosen as alternatives to molecule-based systems, but rather for their new physical and chemical properties, which confer substantive advantages in cellular and medical applications. In this review, we provide insights into immobilization, toxicity and biomedical applications of gold, silver and carbon nanoparticles and discuss their grafting to polymer substrates and the influence on cell-material interactions. The adhesion and the response of cells in contact with the surface play an important role in the cytocompatibility of the implant. It is thus important to understand how cells interact with their environment. The main properties decisive for colonization of a material with cells are surface chemistry, roughness, morphology and polarity, wettability and electrical charge.

Surface properties of thin gold layers sputtered on polymers.

Thin gold layers were sputtered on the foils of polypropylene-PP, polyethyleneterephthalate-PET, polystyrene-PS, polyethylene-PE and polytetrafluoroethylene-PTFE modified by Ar+ plasma. Surface properties of pristine, plasma treated and gold coated polymers were characterized by two-points method (sheet electrical resistance), electrokinetical analysis (zeta-potential, surface chemistry), goniometry (contact angle), electron paramagnetic resonance (concentration of radicals), atomic force microscopy (AFM, surface morphology and roughness) and scratch test (mechanical properties). Zeta potential and contact angle, as assumed, differ dramatically for plasma treated polymers and for the polymers deposited by Au layers. AFM images indicate that after gold deposition on polymers the surface roughness and the surface morphology change depending on pristine polymer surfaces (roughness and morphology) and sputtering time. Electrical measurements resulted in fact that with increasing layer thickness, the sheet resistance of the gold layer decreases for all polymers with increasing sputtering time. Lower adhesive destruction is observed on the gold layer deposited on plasma treated PE in comparison with pristine.