Abstract
A modern trend in traumatology, orthopedics, and implantology is the development of materials and coatings with an amorphous–crystalline structure that exhibits excellent biocopatibility. The structure and physico–chemical and biological properties of calcium phosphate (CaP) coatings deposited on Ti plates using the micro-arc oxidation (MAO) method under different voltages (200, 250, and 300 V) were studied. Amorphous, nanocrystalline, and microcrystalline statesof CaHPO4 and β-Ca2P2O7 were observed in the coatings using TEM and XRD. The increase in MAO voltage resulted in augmentation of the surface roughness Ra from 2.5 to 6.5 µm, mass from 10 to 25 mg, thickness from 50 to 105 µm, and Ca/P ratio from 0.3 to 0.6. The electrical potential (EP) of the CaP coatings changed from −456 to −535 mV, while the zeta potential (ZP) decreased from −53 to −40 mV following an increase in the values of the MAO voltage. Numerous correlations of physical and chemical indices of CaP coatings were estimated. A decrease in the ZP magnitudes of CaP coatings deposited at 200–250 V was strongly associated with elevated hTERT expression in tumor-derived Jurkat T cells preliminarily activated with anti-CD2/CD3/CD28 antibodies and then contacted in vitro with CaP-coated samples for 14 days. In turn, in vitro survival of CD4+ subsets was enhanced, with proinflammatory cytokine secretion of activated Jurkat T cells. Thus, the applied MAO voltage allowed the regulation of the physicochemical properties of amorphous–crystalline CaP-coatings on Ti substrates to a certain extent. This method may be used as a technological mechanism to trigger the behavior of cells through contact with micro-arc CaP coatings. The possible role of negative ZP and Ca2+ as effectors of the biological effects of amorphous–crystalline CaP coatings is discussed. Micro-arc CaP coatings should be carefully tested to determine their suitability for use in patients with chronic lymphoid malignancies.
Highlights
Bioceramic materials based on calcium orthophosphates (CaPO4 ) are actively used in biomaterials [1,2]
When the micro-arc oxidation (MAO) voltage was increased from 200 to 300 V, the following morphological transformations in the coatings were observed (Figure 1): the thickness increased from 50 to 105 μm; the spheres and pores increased in sizes, and the spheres were partially destroyed; the plate-like crystals were formed inside the destroyed hemispheres on the coating surface; local macropores of 15–30 μm in size were formed near the substrate inside the coatings
We propose that rough micro-arc calcium phosphate (CaP) surfaces contain specialized artificial microterritories that simulate the bone milieus for Mesenchymal stem cells (MSCs) differentiation into osteoblasts and hematopoietic stem cells (HSCs) regulation [99]
Summary
Bioceramic materials based on calcium orthophosphates (CaPO4 ) are actively used in biomaterials [1,2] These calcium phosphate (CaP) biomaterials are the most suitable for supporting processes of osseointegration and treatment of bone defects because their structure and chemical composition are similar to the mineral component of mammalian bones and teeth [3,4]. The main disadvantages of bioceramic materials are their unreliable mechanical properties and pronounced fragility [1,2]. This is why metals are widely used as materials for creating structurally reliable orthopedic and dental implants [7]. The surface of implants plays an essential role in the interaction with living tissue [7,8]
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