Antibacterial Properties of Silver-Loaded Plasma Polymer Coatings

In a previous paper, we proposed new silver nanoparticles (SNPs) based antibacterial coatings able to protect eukaryotic cells from SNPs related toxic effects, while preserving antibacterial efficiency. A SNPs containing n-heptylamine (HA) polymer matrix was deposited by plasma polymerization and coated by a second HA layer. In this paper, we elucidate the antibacterial action of these new coatings. We demonstrated that SNPs-loaded material can be covered by thin HA polymer layer without losing the antibacterial activity to planktonic bacteria living in the near surroundings of the material. SNPs-containing materials also revealed antibacterial effect on adhered bacteria. Adhered bacteria number was significantly reduced compared to pure HA plasma polymer and the physiology of the bacteria was affected. The number of adhered bacteria directly decreased with thickness of the second HA layer. Surprisingly, the quantity of cultivable bacteria harvested by transfer to nutritive agar decreased not only with the presence of SNPs, but also in relation to the covering HA layer thickness, that is, oppositely to the increase in adhered bacteria number. Two hypotheses are proposed for this surprising result (stronger attachment or weaker vitality), which raises the question of the diverse potential ways of action of SNPs entrapped in a polymer matrix

Oxidative photopolymerization of thiol-terminated polysulfide resins. Application in antibacterial coatings

A UV photoinduced cross-linking of non-modified commercial poly(disulfide) resins (Thioplast) is reported via the air oxidative photocoupling of terminal thiol functions. Catalyzed by a photogenerated guanidine base (TBD), this step-growth photopolymerization is useful to maximize disulfide functions content. The mechanism proceeds through thiol deprotonation into thiolate anions, further oxidized into thiyl radicals, eventually dimerizing into disulfide cross-links. Starting with a detailed structural characterization of the thiol-terminated resin, photooxidative kinetics are studied under exposure to a polychromatic medium-pressure Hg arc using Raman and infrared spectroscopy. The effects of irradiance, film thickness, photobase concentration, resin molar mass, and content of an additional polythiol monomer (reactive diluent) have been investigated. In an effort of upscaling, irradiation under a 365 nm LED panel has enabled the fast preparation of 1.5 μm thick cross-linked poly(disulfide) coatings in a matter of minutes. Capitalizing on the ability of residual thiol groups to react with silver cations, a post-functionalization has been successfully performed, leading to films exhibiting at their surface stable thiolate-silver bonds as proved by X-ray photoelectron spectroscopy. Despite the well-established biocide action of silver ions, no antibacterial action has been evidenced by confocal fluorescence microscopy because of insufficient release

Biological-like vesicular structures self-assembled from DNA-block copolymers

The polymer modification of short nucleotide sequences has been achieved for future use as self-assembled biologically active structures with sizes in the nanometre range. Co-assembly of the resulting DNA-based amphiphilic block copolymers with native proteins demonstrates the self-assembly of biological-like vesicular structures

Bacterial Colonization of Low‐Wettable Surfaces is Driven by Culture Conditions and Topography

Effect of surface low‐wettability on bacterial colonization has become a prominent subject for the development of antibacterial coatings. However, bacteria's fate on such surfaces immersed in liquid as well as causal factors is poorly understood. This question is addressed by using a range of coatings with increasing hydrophobicity, to superhydrophobic, obtained by an atmospheric plasma polymer method allowing series production. Chemistry, wettability, and topography are thoroughly described, as well as bacterial colonization by in situ live imaging up to 24 h culture time in different liquid media. In the extreme case of superhydrophobic coating, substrates are significantly less colonized in biomolecule‐poor liquids and for short‐term culture only. Complex statistical analysis demonstrates that bacterial colonization on these low‐wettable substrates is predominantly controlled by the culture conditions and only secondary by topographic coating's properties (variation in surface structuration with almost constant mean height). Wettability is less responsible for bacterial colonization reduction in these conditions, but allows the coatings to preserve colonization‐prevention properties in nutritive media when topography is masked by fouling. Even after long‐term culture in rich medium, many large places of the superhydrophobic coating are completely free of bacteria in relation to their capacity to preserve air trapping

XPS as a tool to evaluate organization of aminosilane layers and its impact on bioadhesion

XPS as a tool to evaluate organization of aminosilane layers and its impact on bioadhesio

Impact of Chemical Heterogeneities of Surfaces on Colonization by Bacteria

International audienc

Self-Assembled Molecular Platforms for Bacteria/Material Biointerface Studies: Importance to Control Functional Group Accessibility

International audienc

Vesicular Structures Self-Assembled from Oligonucleotide-Polymer Hybrids: Mechanical Prevention of Bacterial Colonization Upon their Surface Tethering Through Hybridization

International audienc

Bio-based porous zinc phosphates material with silver nanoparticles prepared from casein protein by hydrothermal synthesis for applications in biological environments

The development of silver-based materials has attracted great interest from researchers principally for biomedical and pharmaceutical applications due to the antimicrobial properties and low human toxicity of silver ions in comparison to other heavy metals. Silver nanoparticles supported on inorganic structures such as zeolites, zinc oxide, phosphates, etc., present advantages compared to organic compounds due to their stability and safety 2. Porous zeolite/Ag and fibre-glass/Ag for example are used in water purification to control microbiological contamination. Thus, porous zinc phosphates material containing silver is a promising candidate for this application. Here we report a new approach to substitute inorganic reagents by raw materials with natural origin for the synthesis of zinc phosphates and silver nanoparticles by a hydrothermal method. Hopeite (Zn3(PO4)2.4H2O) enriched in casein and Ag nanoparticles (named Hopeite/CN/Ag°) was prepared by hydrothermal synthesis from the mixture of casein (CN), zinc (II) and silver (I) nitrate solutions. Casein protein from bovine milk was used as a bio-source of phosphorus for the zinc phosphates synthesis as well as a stabilizer in the preparation of silver nanoparticles. Ag nanoparticles with diameter size around 16.0 nm were in situ formed and incorporated in hopeite during the synthesis process. After calcination of the as-synthetized sample, another zinc phosphate material (α-Zn3(PO4)2 and α-Zn2P2O7) enriched in Ag nanoparticles (named ZnPOs/Ag°) was obtained. The antibacterial activity and cytotoxicity of these two materials containing Ag nanoparticles were evaluated. The morphology, porosity and structure of samples were also investigated. Adhesion tests of E. coli SCC1 (Fig. 1) on surfaces after different exposure times to bacteria show that the both solids are not favorable to bacterial growth when compared to a positive control (silicon wafer (WS)). Furthermore, among all the samples, ZnPOs/Ag° reveals a biocide effect after 3h of exposure to bacteria which is ascribed to the released Ag + ions. Moreover, biocompatibility of sample ZnPOs/Ag° for bone marrow stromal cells (STRO-1) was also observed. These results show that sample ZnPOs/Ag° is an interesting antimicrobial and biocompatible material for water disinfection by filtration and biomaterials applications respectively

Bio-based porous zinc phosphates synthesis and its antibacterial properties

Bio-based porous zinc phosphates synthesis and its antibacterial propertie