Biofunctionalization of zirconium with potential application in the biomedical field: an in vitro study

MORENO, ROCÍO; TANO DE LA HOZ M.F.; GOMEZ SANCHEZ A.; MICHELETTI, M.; BARBINI, L.; KATUNAR M.R.; CERE S.

Congreso; XII Latin-American Congress of Artificial Organs and Biomaterials; 2023

Introduction and objective: Zirconium (Zr) is a promising candidate for permanent implants both in orthopedic and dental applications due to its capability of promote the growth of new bone tissue with low cytotoxicity and excellent corrosion resistance [1]. Numerous studies have focused on controlling the interaction between tissue and implanted materials by immobilizing functional biomolecules that could stimulate and interact with the extracellular matrix environment [2]. In this work, the effect of functionalization of Zr and anodized Zr (Zr60) with a bioactive peptide with arginine-glycine-aspartic acid (RGD) sequences as potential manufacturing material for osseointegrable implants to stimulate early bone integration is presented.Methodology: The surfaces of polished Zr (non-anodized) and Zr anodized at 60 V in H3PO4 (Zr60) were functionalized using silanes (APTES) as coupling agents. The surface modifications were evaluated by Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The hydrophilic character of the surfaces, both non-functionalised (Zr and Zr60) and functionalized with RGD peptides (ZrRGD and Zr60RGD), was evaluated by the contact angle method. Electrochemical tests were performed in simulated body fluid solution (SBF) in order to determine the effect of functionalization treatment on the stability of Zr. Finally, the biocompatibility of the material was evaluated in an in vitro cell model. Results and discussion: Surface analysis by Raman spectroscopy showed that the crystal structure of the oxide formed by anodization was predominantly monoclinic. The XPS study showed the presence of peptides on the Zr and Zr60 surfaces after functionalization, although the deposition of the organic film was not uniform. This discontinuity exposed in the Zr60RGD samples the underlying anodic zirconium oxides that have incorporated phosphates from the anodizing solution. In addition, two oxynitride peaks were recognized in the N 1s spectra on the ZrRGD surface. A slight increase in surface free energy was estimated after peptide anchoring on Zr and Zr60 samples. Anodic polarization curves and electrochemical impedance spectroscopy results indicated that both non-functionalized and functionalized with the RGD peptide surfaces present excellent corrosion resistance in SBF. The electrochemical impedance spectroscopy results showed that both types of surfaces behave as non-ideal capacitors, characteristic of passive films on valve metals. The in vitro cell results indicated that the MG-63 osteoblast-like cells present adhesion on both the control (Zr) and biofunctionalized surfaces. However, greater cell adhesion was observed on the surface modified with RGD peptides after 24 h and 48 h of culture. Conclusions: The results provide evidence that it was possible to obtain, via silanization, thin films functionalized with RGD peptides on Zr, although XPS analysis indicates that the organic layer resulting from functionalization could be discontinuous. From the electrochemical results, it can be observed that the functionalization process does not produce any detriment on the surface, which maintains its favourable properties against corrosion in SBF and, in turn, increases the in vitro biocompatibility of the material at short times.References[1] Gomez Sanchez A. et al., Structural characteristics and barrier properties of anodic zirconium oxides for biomedical applications. Sulka, G.D. (eds.). Elsevier, Chapter 10, 321-347, 2020.[2] Alipour M. et al., Recent progress in biomedical applications of RGD-based ligand: From precise cancer theranostics to biomaterial engineering. A systematic review. J Biomed Mater Res A108, 839-850, 2020.