<p>Enhancement of bone consolidation using high-frequency pulsed electromagnetic short-waves and titanium implants coated with biomimetic composite embedded into PLA matrix: in vivo evaluation</p>

Abstract

Purpose Bone consolidation after severe trauma is the most challenging task in orthopedic surgery. This study aimed to develop biomimetic composite for coating Ti implants. Afterwards, these implants were tested in vivo to assess bone consolidation in the absence or the presence of high-frequency pulsed electromagnetic short-waves (HF-PESW). Materials Biomimetic coating was successfully developed using multi-substituted hydroxyapatite (ms-HAP) functionalized with collagen (ms-HAP/COL), embedded into poly-lactic acid (PLA) matrix (ms-HAP/COL@PLA), and subsequently covered with self-assembled COL layer (ms-HAP/COL@PLA/COL, named HAPc). Methods For in vivo evaluation, 32 Wistar albino rats were used in four groups: control group (CG) with Ti implant; PESW group with Ti implant+HF-PESW; HAPc group with Ti implant coated with HAPc; HAPc+PESW group with Ti implant coated with HAPc+HF-PESW. Left femoral diaphysis was fractured and fixed intramedullary. From the first post-operative day, PESW and HAPc+PESW groups underwent HF-PESW stimulation for 14 consecutive days. Biomimetic coating was characterized by XRD, HR-TEM, SEM, EDX and AFM. Results Osteogenic markers (ALP and osteocalcin) and micro-computed tomography (CT) analysis (especially bone volume/tissue volume ratio results) indicated at 2 weeks the following group order: HAPc+PESW>HAPc≈PESW ( P >0.05) and HAPc+PESW>control ( P <0.05), indicating the higher values in HAPc+PESW group compared to CG. The fracture-site bone strength showed, at 2 weeks, the highest average value in HAPc+PESW group. Moreover, histological analysis revealed the most abundant COL fibers assembled in dense bundles in HAPc-PESW group. At 8 weeks, micro-CT indicated higher values only in HAPc+PESW group vs CG ( P <0.05), and histological results showed a complete-healed fracture in groups: HAPc+PESW, HAPc and PESW, but with more advanced bone remodeling in HAPc+PESW group. Conclusion Using Ti implants coated by HAPc jointly with HF-PESW stimulation positively influenced the bone consolidation process, especially in its early phase, thus potentially providing a superior strategy for clinical applications.

<p>Advanced Mg, Zn, Sr, Si Multi-Substituted Hydroxyapatites for Bone Regeneration</p>

“…1,34 The strategy consisted in establishing a starting tailored composition as a new complex hydroxyapatite, noted HAPc, namely HAP-1.5%Mg-0.2%Zn-0.2%Si, where the doping elements are in total under 2 wt%. This choice is based on our previous results, 19,60 and is in accordance with the given data for co-substitution of Mg and Si in the HAP lattice, 5 showing that HAP structure can retain both elements in the total amount of 2 wt%. Further, a working hypothesis has been generated, and it consisted in the addition of Sr within HAPc structure, based on the idea that the four-substituted HAP ceramics are expected to inherit the demonstrated beneficial effects due to HAP structure and to essential elements present in its structure.…”

“…13,14 Innovative strategies are currently in progress for bone regeneration, especially based on bone grafting using biophysical and biochemical stimulation of osteoblasts and simultaneously decreasing the osteoclast activities. Moreover, for a substantial supply of graft biomaterials avoiding donor site injury, hydroxyapatite (HAP) and ms-HAPs, [15][16][17] mimicking the composition of the main inorganic phase of bone, [18][19][20] are still under development.…”

“…The new synthesized nanomaterials have been developed particularly for paste (precipitate) and nanopowder applications, like carriers for local drug delivery, 62,63 injectable gels, 64 or as green (non-sintered) nanoparticles for scaffolding in cell culture, 54,60 as well as for chemical coating onto metallic implants for bone regeneration and healing. 19…”

In-vitro Antibacterial Activity of Novel Nanostructured Composites Based on Forsterite and Silver Nanoparticles

“…On the other hand, the antibacterial mechanism of AgNPs is very complex as recently demonstrated [24][25][26]. Certainly, the nanostructured materials, like nano forsterite, used as carrier of AgNPs are offering new opportunities for orthopedic implant applications [27], particularly against bone infections.…”

Nanomaterials and their role in bone tissue regeneration

“…Используются титановые имплантаты с покрытием из гидроксиапатита и трехмерные матриксы из полимолочной кислоты совместно с гидроксиапатитами, полученными методом 3D печати для улучшения адгезии клеточных структур [23][24][25][26][27]. Ученые из Китая установили, что материалы, изготовленные из одного гидро ксиапатита, не обладают ни биологическими свойствами кости, ни функциями стимулирования васкуляризации и ингибирования иммунного отторжения.…”