Octacalcium Phosphate-Laden Hydrogels on 3D-Printed Titanium Biomaterials Improve Corrosion Resistance in Simulated Biological Media

Abstract

The inflammatory-associated corrosion of metallic dental and orthopedic implants causes significant complications, which may result in the implant’s failure. The corrosion resistance can be improved with coatings and surface treatments, but at the same time, it might affect the ability of metallic implants to undergo proper osteointegration. In this work, alginate hydrogels with and without octacalcium phosphate (OCP) were made on 3D-printed (patterned) titanium alloys (Ti Group 2 and Ti-Al-V Group 23) to enhance their anticorrosion properties in simulated normal, inflammatory, and severe inflammatory conditions in vitro. Alginate (Alg) and OCP-laden alginate (Alg/OCP) hydrogels were manufactured on the surface of 3D-printed Ti substrates and were characterized with wettability analysis, XRD, and FTIR. The electrochemical characterization of the samples was carried out with open circuit potential, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). It was observed that the hydrophilicity of Alg/OCP coatings was higher than that of pure Alg and that OCP phase crystallinity was increased when samples were subjected to simulated biological media. The corrosion resistance of uncoated and coated samples was lower in inflammatory and severe inflammatory environments vs. normal media, but the hydrogel coatings on 3D-printed Ti layers moved the corrosion potential towards more nobler values, reducing the corrosion current density in all simulated solutions. These measurements revealed that OCP particles in the Alg hydrogel matrix noticeably increased the electrical charge transfer resistance at the substrate and coating interface more than with Alg hydrogel alone.

TiO2/PEG as smart anticorrosion and drug-eluting platforms in inflammatory conditions

“…According to the diameter of the capacitive loops in Nyquist plots ( Fig. 3 c), the PEO/PEG-BET-coated Ti had a larger loop radius than PEO, indicating high protection efficiency in both media [ 2 , 3 ]. The Bode modulus plots are also shown in Fig.…”

“…Inflammation triggered after implantation can lead to the release of hypochlorous acid (HOCl) by osteoclasts and white blood cells, creating a local acidic pH region (pH ~ 5) around the implant. Consequently, surface treatment processes are essential to enhance the corrosion resistance of titanium implants in acidic inflammatory environments [ 3 ]. Long-term alleviation of inflammation may be achieved through the systemic delivery of anti-inflammatory drugs on the Ti surface.…”

Calcium Phosphate Biomaterials for 3D Bioprinting in Bone Tissue Engineering

“…In another study, hydrogel loaded with a VEGF-mimetic peptide (QK) demonstrated the ability to enhance tube formation in human umbilical vein endothelial cells (HUVECs), elevate the expression of angiogenesis-related genes (Flt1, Kdr and VEGF) in BMSCs (Figure 3f) and recruit BMSCs, collectively contributing to the establishment of an osteogenic microenvironment for bone repair [81]. Bordbar-Khiabani et al explored 3D-printed titanium alloys that were covered with alginate hydrogels with and without OCP to improve their resistance to corrosion under simulated normal, inflammatory and severe inflammatory conditions in vitro [82]. The findings indicated that alginate hydrogel/OCP coatings exhibited higher hydrophilicity compared to that of pure alginate hydrogel.…”

Titanium Implants Coated with Hydroxyapatite Used in Orbital Wall Reconstruction—A Literature Review

“…Additionally, the corrosion resistance is significantly reduced when lactic acid and H 2 O 2 are present [53]. Further research has demonstrated that hydrogel coatings can serve as a barrier, preventing chloride and lactate ions in simulated biological environments from causing corrosion to the underlying material, thus enhancing the Ti alloy's resistance to corrosion [54].…”