Electrophoretically Deposited Chitosan/Eudragit E 100/AgNPs Composite Coatings on Titanium Substrate as a Silver Release System

Due to the possibility of bacterial infections occurring around peri-implant tissues, it is necessary to provide implant coatings that release antibacterial substances. The scientific goal of this paper was to produce by electrophoretic deposition (EPD) a smart, chitosan/Eudragit E 100/silver nanoparticles (chit/EE100/AgNPs) composite coating on the surface of titanium grade 2 using different deposition parameters, such as the content of AgNPs, applied voltage, and time of deposition. The morphology, surface roughness, thickness, chemical and phase composition, wettability, mechanical properties, electrochemical properties, and silver release rate at different pH were investigated. Using lower values of deposition parameters, coatings with more homogeneous morphology were obtained. The prepared coatings were sensitive to the reduced pH environment.

The Manufacture and Characterization of Silver Diammine Fluoride and Silver Salt Crosslinked Nanocrystalline Cellulose Films as Novel Antibacterial Materials

There is an unmet need for biocompatible, anti-infective, and mechanically strong hydrogels. This study investigated the use of poly vinyl alcohol (PVA), polysaccharides, and nanocrystalline cellulose (CNC) to deliver silver in a controlled manner for possible use against oral or wound bacteria. Silver was included in solvent cast films as silver diammine fluoride (SDF) or as nitrate, sulphate, or acetate salts. Hydrogel formation was assessed by swelling determinations and silver release was measured using inductively coupled plasma methods. Antibacterial studies were performed using Gram-positive and negative bacteria turbidity assays. PVA formed homogenous, strong films with SDF and swelled gently (99% hydrolyzed) or vigorously with dissolution (88% hydrolyzed) and released silver slowly or quickly, respectively. CNC-SDF films swelled over a week and formed robust hydrogels whereas CNC alone (no silver) disintegrated after two days. SDF loaded CNC films released silver slowly over 9 days whereas films crosslinked with silver salts were less robust and swelled and released silver more quickly. All silver loaded films showed good antibacterial activity. CNC may be crosslinked with silver in the form of SDF (or any soluble silver salt) to form a robust hydrogel suitable for dental use such as for exposed periodontal debridement areas.

Exploring hierarchical porous silica-supported Ag3PO4 as high-efficient and environmental-friendly photocatalytic disinfectant

Silver orthophosphate (Ag3PO4) is an attractive photocatalytic catalyst for disinfection and degradation, but its instability arising from silver release generates significant environmental issue. Aiming to develop a highly efficient and environmental-friendly catalyst, we synthesized Ag3PO4 nanoparticle incorporated hierarchical porous silica (Ag3PO4@h-SiO2) as a novel high-performance photocatalytic catalyst without observed silver release. Brain-like hierarchical porous SiO2 (h-SiO2) brings a scaffold support with high surface areas, and the h-SiO2 surface modified thiols are able to anchor in situ formed 10 nm Ag3PO4 to eliminate silver release. Systematic investigations revealed that because of its structural advantages, Ag3PO4@h-SiO2 show excellent disinfection and degradation ability under visible-light irradiation and stable characteristics without obviously observed silver leaching during photo-oxidation operation. In-depth scavenger study reveals Ag3PO4@h-SiO2 as an effective semiconducting photocatalyst stimulates the production of photo-generated reactive species, which dominate its distinguished disinfection performance via photo-oxidation. Graphical abstract Ag3PO4 are anchored to thiol modified hierarchical porous SiO2 to produce a visible-light responsive photocatalyst of Ag3PO4@h-SiO2. The enhanced catalytic sites and surface areas promote pathogen disinfection, and the structure advantages minimize silver release to environment. Both H2O2 and holes being generated in photocatalysis dominate overall disinfection activity.

Comparative Analysis of Electrospun Uniaxial and Coaxial Nanofibers Properties

Coaxial electrospinning, which is a modified electrospinning technique involving an arrangement of multiple solution feed systems, enable the production of multilayered nanofibers. In this study, multilayered nanofibers of polyamide 6 (core) / polycaprolactone (shell) containing silver nanoparticles in the core were produced by coaxial electrospinning method. UV-Visible spectra showed that the size of nanoparticles were about 10 nm and the content of nanoparticles were observed to be proportional to the precursor content added to the solvent. The obtained multilayered nanofibers were characterized in terms of morphology, chemical structure, and silver release properties. The multilayered nanofiber structure was confirmed by the selective dissolution and removal of shell layer. The increase in the PCL content of the multilayered nanofibers with the increase in the flow rate of the shell solution was confirmed by FTIR. The silver release profiles of the nanofibers were observed to be dependent on the nanofiber configuration, and silver content. Shell thickness was also an important parameter affecting the silver release properties for multilayered nanofibers.

The role of silver coating for arthroplasty components

Periprosthetic joint infection (PJI) is one of the most dreaded complications after arthroplasty surgery; thus numerous approaches have been undertaken to equip metal surfaces with antibacterial properties. Due to its antimicrobial effects, silver is a promising coating for metallic surfaces, and several types of silver-coated arthroplasty implants are in clinical use today. However, silver can also exert toxic effects on eukaryotic cells both in the immediate vicinity of the coated implants and systemically. In most clinically-used implants, silver coatings are applied on bulk components that are not in direct contact with bone, such as in partial or total long bone arthroplasties used in tumour or complex revision surgery. These implants differ considerably in the coating method, total silver content, and silver release rates. Safety issues, such as the occurrence of argyria, have been a cause for concern, and the efficacy of silver coatings in terms of preventing PJI is also controversial. The application of silver coatings is uncommon on parts of implants intended for cementless fixation in host bone, but this option might be highly desirable since the modification of implant surfaces in order to improve osteoconductivity can also increase bacterial adhesion. Therefore, an optimal silver content that inhibits bacterial colonization while maintaining osteoconductivity is crucial if silver were to be applied as a coating on parts intended for bone contact. This review summarizes the different methods used to apply silver coatings to arthroplasty components, with a focus on the amount and duration of silver release from the different coatings; the available experience with silver-coated implants that are in clinical use today; and future strategies to balance the effects of silver on bacteria and eukaryotic cells, and to develop silver-coated titanium components suitable for bone ingrowth. Cite this article: Bone Joint J 2021;103-B(3):423–429.