Chitosan reinforced apatite-wollastonite coating by electrophoretic deposition on titanium implants

Bioactive apatite-wollastonite glass ceramics coating on metallic titanium for biomedical applications: effect of boron

Metallic titanium (Ti) implant surfaces need improvement for bioproperties and antibacterial behavior. For this purpose, a new boron-doped bioactive apatite-wollastonite (AW) coating was successfully developed on the Ti plate surface. The effects of boron addition on the microstructure, mechanical properties, and bioproperties of the AW coating were investigated. With the addition of boron (B), the AW coating morphology became less porous and compact. In terms of bio properties, the rate of apatite formation increased with the addition of B, and the cell viability rate increased from approximately 66-81%. B addition increased the elastic modulus of the AW coating from about 24-46 GPa and increased its hardness about 2.5 times. In addition, while no antibacterial activity was observed in the AW coating, the addition of boron slightly introduced antibacterial properties. The novel AW/B composite coating obtained is promising for Ti implant surfaces.

Mesenchymal Stromal/Stem Cell (MSC)-Based Vector Biomaterials for Clinical Tissue Engineering and Inflammation Research: A Narrative Mini Review

Mesenchymal stromal/stem cells (MSCs) have the ability of self-renewal, the potential of multipotent differentiation, and a strong paracrine capacity, which are mainly used in the field of clinical medicine including dentistry and orthopedics. Therefore, tissue engineering research using MSCs as seed cells is a current trending directions. However, the healing effect of direct cell transplantation is unstable, and the paracrine/autocrine effects of MSCs cannot be effectively elicited. Tumorigenicity and heterogeneity are also concerns. The combination of MSCs as seed cells and appropriate vector materials can form a stable cell growth environment, maximize the secretory features of stem cells, and improve the biocompatibility and mechanical properties of vector materials that facilitate the delivery of drugs and various secretory factors. There are numerous studies on tissue engineering and inflammation of various biomaterials, mainly involving bioceramics, alginate, chitosan, hydrogels, cell sheets, nanoparticles, and three-dimensional printing. The combination of bioceramics, hydrogels and cell sheets with stem cells has demonstrated good therapeutic effects in clinical applications. The application of alginate, chitosan, and nanoparticles in animal models has also shown good prospects for clinical applications. Three-dimensional printing technology can circumvent the shortage of biomaterials, greatly improve the properties of vector materials, and facilitate the transplantation of MSCs. The purpose of this narrative review is to briefly discuss the current use of MSC-based carrier biomaterials to provide a useful resource for future tissue engineering and inflammation research using stem cells as seed cells.

Nanocomposites for Enhanced Osseointegration of Dental and Orthopedic Implants Revisited: Surface Functionalization by Carbon Nanomaterial Coatings

Over the past few decades, carbon nanomaterials, including carbon nanofibers, nanocrystalline diamonds, fullerenes, carbon nanotubes, carbon nanodots, and graphene and its derivatives, have gained the attention of bioengineers and medical researchers as they possess extraordinary physicochemical, mechanical, thermal, and electrical properties. Recently, surface functionalization with carbon nanomaterials in dental and orthopedic implants has emerged as a novel strategy for reinforcement and as a bioactive cue due to their potential for osseointegration. Numerous developments in fabrication and biological studies of carbon nanostructures have provided various novel opportunities to expand their application to hard tissue regeneration and restoration. In this minireview, the recent research trends in surface functionalization of orthopedic and dental implants with coating carbon nanomaterials are summarized. In addition, some seminal methodologies for physicomechanical and electrochemical coatings are discussed. In conclusion, it is shown that further development of surface functionalization with carbon nanomaterials may provide innovative results with clinical potential for improved osseointegration after implantation.

Surface functionalization of chitosan as a coating material for orthopaedic applications: A comprehensive review

Metallic implants have dominated the biomedical implant industries for the past century for load-bearing applications, while the polymeric implants have shown great promise for tissue engineering applications. The surface properties of such implants are critical as the interaction of implant surfaces, and the body tissues may lead to unfavourable reactions. Desired implant properties are biocompatibility, corrosion resistance, and antibacterial activity. A polymer coating is an efficient and economical way to produce such surfaces. A lot of research has been carried out on chitosan (CS)-modified metallic and polymer scaffolds in the last decade. Different methods such as electrophoretic deposition, sol-gel methods, dip coating and spin coating, electrospinning, etc. have been utilized to produce CS coatings. However, a systematic review of chitosan coatings on scaffolds focussing on widely employed techniques is lacking. This review surveys literature concerning the current status of orthopaedic applications of CS for the purpose of coatings. In this review, the various preparation methods of coating, and the role of the surface functionalities in determining the efficiency of coatings are discussed. Effect of nanoparticle additions on the polymeric interfaces and in regulating the properties of surface coatings are also investigated in detail.

Low-Cost Deposition of Antibacterial Ion-Substituted Hydroxyapatite Coatings onto 316L Stainless Steel for Biomedical and Dental Applications

Substitutions of ions into an apatitic lattice may result in antibacterial properties. In this study, magnesium (Mg)-, zinc (Zn)-, and silicon (Si)-substituted hydroxyapatite (HA) were synthesized using a microwave irradiation technique. Polyvinyl alcohol (PVA) was added during the synthesis of the substituted HA as a binding agent. The synthesized Mg-, Zn-, and Si-substituted HAs were then coated onto a 316L-grade stainless-steel substrate using low-cost electrophoretic deposition (EPD), thereby avoiding exposure to high temperatures. The deposited layer thickness was measured and the structural, phase and morphological analysis were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. The bacterial adhesion of Staphylococcus aureus was characterized at 30 min, 2 h and 6 h. The results showed homogeneous, uniform thickness (50–70 µm) of the substrate. FTIR and XRD showed the characteristic spectral peaks of HA, where the presence of Mg, Zn and Si changed the spectral peak intensities. The Mg–HA coating showed the least bacterial adhesion at 30 min and 2 h. In contrast, the Si–HA coating showed the least adhesion at 6 h. EPD showed an effective way to get a uniform coating on bio-grade metal implants, where ionic-substituted HA appeared as alternative coating material compared to conventional HA and showed the least bacterial adhesion.

Electrodeposition of Polysaccharide and Protein Hydrogels for Biomedical Applications

In the last few decades, polysaccharide and protein hydrogels have attracted significant attentions and been applied in various engineering fields. Polysaccharide and protein hydrogels with appealing physical and biological features have been produced to meet different biomedical applications for their excellent properties related to biodegradability, biocompatibility, nontoxicity, and stimuli responsiveness. Numerous methods, such as chemical crosslinking, photo crosslinking, graft polymerization, hydrophobic interaction, polyelectrolyte complexation and electrodeposition have been employed to prepare polysaccharide and protein hydrogels. Electrodeposition is a facile way to produce different polysaccharide and protein hydrogels with the advantages of temporal and spatial controllability. This paper reviews the recent progress in the electrodeposition of different polysaccharide and protein hydrogels. The strategies of pH induced assembly, Ca2+ crosslinking, metal ions induced assembly, oxidation induced assembly derived from electrochemical methods were discussed. Pure, binary blend and ternary blend polysaccharide and protein hydrogels with multiple functionalities prepared by electrodeposition were summarized. In addition, we have reviewed the applications of these hydrogels in drug delivery, tissue engineering and wound dressing.

Inducing apatite pre-layer on titanium surface through hydrothermal processing for osseointegration

Commercially available titanium (Ti) having high mechanical strength and a low area of cross-section can be adequately exploited for minimally invasive dental implantation. Current directions in clinical dental implant therapy focus on endosseous dental implant surfaces with nanoscale topographies using easy and economical processing approaches. The present study describes the generation of a novel nanolayer nucleating agent on the surface of Ti implant for early endosseous after implantation. The strategy is to modify the surface of Ti implant using Ca(OH)₂ via hydrothermal technique (Ti-HT). The X-ray photoelectron spectroscopy analysis confirmed the presence of chemically bonded Ca ions on the Ti surface in the form of CaTiO₃. In vitro studies are carried out to confirm the bone bonding ability of calcium enriched Ti surface. The apatite deposition on the surface after exposure to SBF for 7 days is confirmed via scanning electron microscopy, X-ray powder diffraction, Fourier-transform infrared spectroscopy and energy-dispersive X-ray spectroscopy techniques. The cell viability of Ti-HT was evaluated using direct contact method and MTT assay. The potential of Ca²⁺ ion on Ti surface via hydrothermal pre-treatment to enhance osseointegration of Ti has been proposed for achieving early stability for dental implants.

Single-step electrochemical deposition of antimicrobial orthopaedic coatings based on a bioactive glass/chitosan/nano-silver composite system

Composite orthopaedic coatings with antibacterial capability containing chitosan, Bioglass® particles (9.8μm) and silver nanoparticles (Ag-np) were fabricated using a single-step electrophoretic deposition (EPD) technique, and their structural and preliminary in vitro bactericidal and cellular properties were investigated. Stainless steel 316 was used as a standard metallic orthopaedic substrate. The coatings were compared with EPD coatings of chitosan and chitosan/Bioglass®. The ability of chitosan as both a complexing and stabilizing agent was utilized to form uniformly deposited Ag-np. Due to the presence of Bioglass® particles, the coatings were bioactive in terms of forming carbonated hydroxyapatite in simulated body fluid (SBF). Less than 7wt.% of the incorporated silver was released over the course of 28days in SBF and the possibility of manipulating the release rate by varying the deposition order of coating layers was shown. The low released concentration of Ag ions (<2.5ppm) was efficiently antibacterial against Staphyloccocus aureus up to 10days. Although chitosan and chitosan/Bioglass® coating supported proliferation of MG-63 osteoblast-like cells up to 7days of culture, chitosan/Bioglass®/Ag-np coatings containing 342 μg of Ag-np showed cytotoxic effects. This was attributed to the relatively high concentration of Ag-np incorporated in the coatings.

Electrophoretic deposition of biomaterials

Electrophoretic deposition (EPD) is attracting increasing attention as an effective technique for the processing of biomaterials, specifically bioactive coatings and biomedical nanostructures. The well-known advantages of EPD for the production of a wide range of microstructures and nanostructures as well as unique and complex material combinations are being exploited, starting from well-dispersed suspensions of biomaterials in particulate form (microsized and nanoscale particles, nanotubes, nanoplatelets). EPD of biological entities such as enzymes, bacteria and cells is also being investigated. The review presents a comprehensive summary and discussion of relevant recent work on EPD describing the specific application of the technique in the processing of several biomaterials, focusing on (i) conventional bioactive (inorganic) coatings, e.g. hydroxyapatite or bioactive glass coatings on orthopaedic implants, and (ii) biomedical nanostructures, including biopolymer-ceramic nanocomposites, carbon nanotube coatings, tissue engineering scaffolds, deposition of proteins and other biological entities for sensors and advanced functional coatings. It is the intention to inform the reader on how EPD has become an important tool in advanced biomaterials processing, as a convenient alternative to conventional methods, and to present the potential of the technique to manipulate and control the deposition of a range of nanomaterials of interest in the biomedical and biotechnology fields.