ABSTRACT
In this study, to address the susceptibility of 3D-printed titanium implants to bacterial infection, we propose to form a chitosan/ZnO composite coating by electrophoretic deposition to enhance its antimicrobial, biocompatible, and mechanical properties. The surface morphology of the composite coating is relatively flat, showing good hydrophilicity and coating adhesion, and the corrosion current density is significantly lower than that of the untreated titanium alloy. According to the results of the study, the composite coatings containing more than 0.1â¯g of ZnO (Z2, Z3, Z4 groups) showed excellent antibacterial effects against Staphylococcus aureus and Escherichia coli, with antibacterial rates of more than 95â¯%, and the medium-concentration ZnO coatings (Z2 group) showed good cellular activity, with cell viability rates of more than 80â¯%. In contrast, the high-concentration ZnO coatings (Z3, Z4 groups) showed a certain degree of cytotoxicity. The inherent film-forming property of the composite coating enabled the cells to adhere well to the coating surface. It was found through SBF body fluid immersion that Zn²âº can increase the rate of hydroxyapatite precipitation and enhance bioactivity. These results emphasize the importance of precise control of the ZnO content in the improved antimicrobial and biocompatible chitosan-ZnO composite coatings to ensure excellent antimicrobial properties and necessary biocompatibility.
ABSTRACT
Objective: This study aims to develop and evaluate the biocompatibility and osteogenic potential of a novel injectable strontium-doped hydroxyapatite bone-repair material. Methods: The properties of strontium-doped hydroxyapatite/chitosan (Sr-HA/CS), hydroxyapatite/chitosan (HA/CS) and calcium phosphate/chitosan (CAP/CS) were assessed following their preparation via physical cross-linking and a one-step simplified method. Petri dishes containing Escherichia coli and Staphylococcus epidermidis were inoculated with the material for in vitro investigations. The material was also co-cultured with stem cells derived from human exfoliated deciduous teeth (SHEDs), to assess the morphology and proliferation capability of the SHEDs, Calcein-AM staining and the Cell Counting Kit-8 assay were employed. Osteogenic differentiation of SHEDs was determined using alkaline phosphatase (ALP) staining and Alizarin Red staining. For in vivo studies, Sr-HA/CS was implanted into the muscle pouch of mice and in a rat model of ovariectomy-induced femoral defects. Hematoxylin-eosin (HE) staining was performed to determine the extent of bone formation and defect healing. The formation of new bone was determined using Masson's trichrome staining. The osteogenic mechanism of the material was investigated using Tartrate-resistant acid phosphatase (TRAP) staining and immunohistochemical studies. Results: X-ray diffraction (XRD) and energy-dispersive spectroscopy (EDS) showed that strontium was successfully doped into HA. The Sr-HA/CS material can be uniformly squeezed using a syringe with a 13% swelling rate. Sr-HA/CS had a significant antibacterial effect against both E. coli and S. epidermidis (p < 0.05), with a stronger effect observed against E. coli. The Sr-HA/CS significantly improved cell proliferation and cell viability in vitro studies (p < 0.05). Compared to CAP/CS and CS, Sr-HA/CS generated a substantially greater new bone area during osteoinduction experiments (p < 0.05, p < 0.001). The Sr-HA/CS material demonstrated a significantly higher rate of bone repair in the bone defeat studies compared to the CAP/CS and CS materials (p < 0.01). The OCN-positive area and TRAP-positive cells in Sr-HA/CS were greater than those in control groups (p < 0.05). Conclusion: A novel injectable strontium-doped HA bone-repair material with good antibacterial properties, biocompatibility, and osteoinductivity was successfully prepared.