Electrophoretic Deposition of PEEK/45S5 Bioactive Glass Coating on Porous Titanium Substrate: Influence of Processing Conditions and Porosity Parameters

Abstract

Commercially pure titanium (cp Ti) is typically accepted as one of the best in vitro and in vivo bone replacement biomaterial, due to its excellent balance between biomechanical and biofunctional properties. In that context, the aim of this work is to prove the hypothesis of a simultaneous solution to certain specific limitations of cpTi, which can often compromise the reliability of implants: (i) stress-shielding phenomenon, and (ii) a deficient biointerface with bone, which reduces the osseointegration. Porous samples of cp Ti, grade IV, were obtained by space-holder technique (50 vol.% NH4HCO3, 800 MPa, at 1250 oC during 2h, under high vacuum), to produce a good balance between Young ́s Modulus and yield strength. Different types of porous samples were manufactured by considering different size particles ranges of NH4HCO3: 100-200μm, 250-355μm and 355-500μm. Afterwards, they were coated with a PEEK/45S5 bioactive glass composite by electrophoretic deposition, to be finally sintered at 350oC for 1h. The coatings homogeneity, infiltration efficiency, adhesion and cracking, were studied in order to establish correlations with processing conditions (time of deposition, applied voltage, composition, concentration and stability of the colloidal suspension). Detailed structural characterization of the coatings was performed (SEM and XRD), besides the contact angle and contact profilometry testing. Additional mechanical and chemical insights were achieved by evaluating both the tribo-mechanical (instrumented microindentation and micro-scratch testing) and electrochemical behaviors (potentiodynamic polarization and in vitro corrosion tests in SBF). All these results allowed us to determine the optimal balance of properties for a porous substrate (space holder of 250-355μm) with a coating obtained for 65 V, 2 min, 6 mm (distance between electrodes), 10 g/L bioactive glass and 20 g/l PEEK. The high adhesion estimated between the bioactive/biopolymer coatings and the porous titanium substrates (excellent infiltration) suggest that this new biocomposite is a good candidate for load-bearing applications.

Sol-gel deposition of hydroxyapatite coatings on porous titanium for biomedical applications

“…1a). Total pore fraction, mean size and the high degree of interconnectivity ensure the bone ingrowth and the infiltration of HA [31].…”

Electrophoretic deposition of lawsone loaded bioactive glass (BG)/chitosan composite on polyetheretherketone (PEEK)/BG layers as antibacterial and bioactive coating

“…PEEK is often employed as a mechanically robust biomaterial for orthopedic, trauma, and spinal implants . PEEK consists of an aromatic backbone molecular chain, interconnected by ketone and ether functional groups . PEEK is compatible with bioactive inorganic materials, including hydroxyapatite and bioactive glasses (BGs), which can be used either as a composite filler or as surface coating .…”

“…13,14 PEEK consists of an aromatic backbone molecular chain, interconnected by ketone and ether functional groups. [14][15][16][17] PEEK is compatible with bioactive inorganic materials, including hydroxyapatite and bioactive glasses (BGs), which can be used either as a composite filler or as surface coating. 13,18,19 In addition, PEEK/BG composite layers can act as substrate to be further coated with biodegradable composite coatings loaded with antibiotics to provide improved surfaces for antiseptic bonding to tissues.…”

Recent Advancements in Materials and Coatings for Biomedical Implants

“…A cold sprayed Bioglass/PEEK composite prepared by Garrido et al [143] showed an increase in wear resistance by more than 70%, higher hardness, and a lower coefficient of friction compared to pure PEEK. Coatings based on Bioglass/PEEK on porous Ti substrates resulted in higher adhesion between Bioglass/PEEK coating and Ti substrates [144].…”