Biomimetic Composite Coatings for Activation of Titanium Implant Surfaces: Methodological Approach and In Vivo Enhanced Osseointegration

Abstract

Innovative nanomaterials are required for the coatings of titanium (Ti) implants to ensure the activation of Ti surfaces for improved osseointegration, enhanced bone fracture healing and bone regeneration. This paper presents a systematic investigation of biomimetic composite (BC) coatings on Ti implant surfaces in a rat model of a diaphyseal femoral fracture. Methodological approaches of surface modification of the Ti implants via the usual joining methods (e.g., grit blasting and acid etching) and advanced physicochemical coating via a self-assembled dip-coating method were used. The biomimetic procedure used multi-substituted hydroxyapatite (ms-HAP) HAP-1.5 wt% Mg-0.2 wt% Zn-0.2 wt% Si nanoparticles (NPs), which were functionalized using collagen type 1 molecules (COL), resulting in ms-HAP/COL (core/shell) NPs that were embedded into a polylactic acid (PLA) matrix and finally covered with COL layers, obtaining the ms-HAP/COL@PLA/COL composite. To assess the osseointegration issue, first, the thickness, surface morphology and roughness of the BC coating on the Ti implants were determined using AFM and SEM. The BC-coated Ti implants and uncoated Ti implants were then used in Wistar albino rats with a diaphyseal femoral fracture, both in the absence and the presence of high-frequency pulsed electromagnetic shortwave (HF-PESW) stimulation. This study was performed using a bone marker serum concentration and histological and computer tomography (micro-CT) analysis at 2 and 8 weeks after surgical implantation. The implant osseointegration was evaluated through the bone–implant contact (BIC). The bone–implant interface was investigated using FE-SEM images and EDX spectra of the retrieved surgical implants at 8 weeks in the four animal groups. The obtained results showed significantly higher bone–implants contact and bone volume per tissue volume, as well as a greater amount of newly formed bone, in the BC-coated Ti implants than in the uncoated Ti implants. Direct bone–implant contact was also confirmed via histological examination. The results of this study confirmed that these biomimetic composite coatings on Ti implants were essential for a significant enhancement of osseointegration of BC-coated Ti implants and bone regeneration. This research provides a novel strategy for the treatment of bone fractures with possible orthopedic applications.

Forsterite as an Alternative for Orthopaedic Implants – Short Review

“…A future focus would be on a better tailoring of forsterite ceramic scaffolds. This could also mean improving upon the natural properties of forsterite by ionic substitutions following the trend found in hydroxyapatite [109][110][111]. To our knowledge, there is not much information in regards to this.…”

Recent Trends in Hydroxyapatite Supplementation for Osteoregenerative Purposes

“…Next, a complex ms-HAP/COL@PLA/COL composite was obtained by additional embedment into a polylactic acid (PLA) matrix and finally covered with COL layers. Testing revealed the important osseointegration of implants as well as improved bone regeneration [ 173 ]. Similarly, nano-hydroxyapatite (HAP) substituted with multiple cations (Sr 2+ , Mg 2+ and Zn 2+ ) demonstrated a measurable in vitro ion release [ 174 ].…”

Silymarin Based Complexes – a mini review

“…The substituted elements can lead to beneficial effects on morphology, structure and mechanical properties. HAP can be used in bone tissue engineering, implant coating, dental materials and drug carriers [50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65][66][67].…”