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

ROCIO MORENO; FLORENCIA TANO DE LA HOZ; ANDREA GOMEZ SANCHEZ; MELISA MICHELETTI; LUCIANA BARBINI; MARIA ROSA KATUNAR; SILVIA CERE

Congreso; 12 COLAOB; 2023

Keywords: RGD peptide; Zirconium; Surface characterization; Biomimetic surfaceIntroduction and objective: Zirconium (Zr) is a promising candidate for permanent implants both in orthopedicand dental applications due to its capability of promote the growth of new bone tissue with low cytotoxicityand excellent corrosion resistance [1]. Numerous studies have focused on controlling the interaction betweentissue and implanted materials by immobilizing functional biomolecules that could stimulate and interact withthe 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 manufacturingmaterial 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 H 3 PO 4 (Zr60) werefunctionalized using silanes (APTES) as coupling agents. The surface modifications were evaluated by Ramanspectroscopy 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 thecontact angle method. Electrochemical tests were performed in simulated body fluid solution (SBF) in order todetermine the effect of functionalization treatment on the stability of Zr. Finally, the biocompatibility of thematerial was evaluated in an in vitro cell model.Results and discussion: Surface analysis by Raman spectroscopy showed that the crystal structure of the oxideformed by anodization was predominantly monoclinic. The XPS study showed the presence of peptides on theZr and Zr60 surfaces after functionalization, although the deposition of the organic film was not uniform. Thisdiscontinuity exposed in the Zr60RGD samples the underlying anodic zirconium oxides that have incorporatedphosphates from the anodizing solution. In addition, two oxynitride peaks were recognized in the N 1s spectraon the ZrRGD surface. A slight increase in surface free energy was estimated after peptide anchoring on Zr andZr60 samples. Anodic polarization curves and electrochemical impedance spectroscopy results indicated thatboth non-functionalized and functionalized with the RGD peptide surfaces present excellent corrosionresistance in SBF. The electrochemical impedance spectroscopy results showed that both types of surfacesbehave as non-ideal capacitors, characteristic of passive films on valve metals. The in vitro cell results indicatedthat 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 ofculture.Conclusions: The results provide evidence that it was possible to obtain, via silanization, thin filmsfunctionalized with RGD peptides on Zr, although XPS analysis indicates that the organic layer resulting fromfunctionalization could be discontinuous. From the electrochemical results, it can be observed that thefunctionalization process does not produce any detriment on the surface, which maintains its favourableproperties against corrosion in SBF and, in turn, increases the in vitro biocompatibility of the material at shorttimes.References[1] Gomez Sanchez A. et al., Structural characteristics and barrier properties of anodic zirconium oxides for biomedicalapplications. 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 tobiomaterial engineering. A systematic review. J Biomed Mater Res A108, 839-850, 2020.