Titanium-Dioxide-Nanoparticle-Embedded Polyelectrolyte Multilayer as an Osteoconductive and Antimicrobial Surface Coating

Abstract

Bioactive surface coatings have retained the attention of researchers and physicians due to their versatility and range of applications in orthopedics, particularly in infection prevention. Antibacterial metal nanoparticles (mNPs) are a promising therapeutic, with vast application opportunities on orthopedic implants. The current research aimed to construct a polyelectrolyte multilayer on a highly porous titanium implant using alternating thin film coatings of chitosan and alginate via the layer-by-layer (LbL) self-assembly technique, along with the incorporation of silver nanoparticles (AgNPs) or titanium dioxide nanoparticles (TiO2NPs), for antibacterial and osteoconductive activity. These mNPs were characterized for their physicochemical properties using quartz crystal microgravimetry with a dissipation system, nanoparticle tracking analysis, scanning electron microscopy, and atomic force microscopy. Their cytotoxicity and osteogenic differentiation capabilities were assessed using AlamarBlue and alkaline phosphatase (ALP) activity assays, respectively. The antibiofilm efficacy of the mNPs was tested against Staphylococcus aureus. The LbL polyelectrolyte coating was successfully applied to the porous titanium substrate. A dose-dependent relationship between nanoparticle concentration and ALP as well as antibacterial effects was observed. TiO2NP samples were also less cytotoxic than their AgNP counterparts, although similarly antimicrobial. Together, these data serve as a proof-of-concept for a novel coating approach for orthopedic implants with antimicrobial and osteoconductive properties.

Recent Advances in Antibacterial Coatings to Combat Orthopedic Implant-Associated Infections

“…In addition to polymeric antibacterial coatings, various studies have reported on coatings based on lipids and those developed from nanoparticles [ 26 , 68 , 69 , 70 ]. Owing to their potential responsivity to external stimuli (including magnetic field, temperature, and light) and typical strong antibacterial effects, metallic nanoparticles are one of the most utilized nanomaterials for antibacterial coatings, either by direct immobilization or embedding in polymeric layers [ 71 , 72 ]. Most coatings are developed from biopolymers with molecular and functional versatilities, allowing the development of coatings with the desired properties and enabling their functionalization with bioactive moieties or antibiotics [ 6 , 7 , 27 ].…”

“…Further, it is worth exploring the possible functionalization of hydrogels or polymeric matrices by embedding the corresponding nanoparticles of the inverse non-lamellar lyotropic liquid crystalline phases (particularly cubosomes and hexosomes), which are recently popular nano-self-assemblies in the development of nanocarriers for drug delivery applications [ 124 , 125 , 126 , 127 , 128 , 129 , 130 , 131 , 132 , 133 , 134 , 135 , 136 , 137 , 138 , 139 , 140 , 141 , 142 ], or through their immobilization for designing cubosome or hexosome coatings by employing chemical surface activation methods. The latter strategy is typically applied for immobilization of lamellar liquid crystalline nanoparticles (liposomes) and various soft and hard nanoparticles (such as silver nanoparticles) [ 49 , 70 , 72 , 105 ]. The design of such antibacterial coatings through the use of non-lamellar phases is rarely investigated [ 143 ].…”