Effect of zinc oxide micro- and nanoparticles on cytotoxicity, antimicrobial activity and mechanical properties of apatite-polymer osteoplastic material.

This work is devoted to the comparison of the physical and biological properties of synthesized osteoplastic composites with an experimentally determined content (375 µg/g) of the micro (ZnOMPs) and nano (ZnONPs) particles, immobilized in Hydroxyapatite-Alginate-Chitosan matrix (HA-Alg-CS). ZnONPs show pronounced antimicrobial activity against E.coli ATCC 25922 and S. aureus ATCC 25923, while ZnOMPs only in the CS presence. Composites containing ZnONPs/MPs do not have a toxic effect on bone-forming cells - osteoblasts, preserving their ability to biomineralization. ZnOMPs and ZnONPs to varying degrees, but significantly affect composites' swelling, porosity, shape stability, and prolong vitamin D3 release for 120h, compared to Control. Composites do not demonstrate unwanted "burst release." ZnONPs/MPs increase Youngs' modulus of the HA-Alg matrix, namely 348 â†’ 419 MPa (ZnOMPs), 348 â†’ 646 MPa (ZnONPs), and weaken the plastic (irreversible) deformations. The compressive strength of HA-Alg and HA-Alg/CS matrixes containing ZnONPs (178 MPa and 251 MPa, respectively) is in the range of values for native cortical bone (170-193 MPa). Biocompatibility and lack of toxic effect give both composites a perspective for osteoplastic application, but composites doped with ZnONPs are more attractive.

Shaping the Structure and Properties of TiO2-ZnO Oxide Coatings Produced by Plasma Electrolytic Oxidation on Titanium Substrate.

The paper presents the results of preliminary research on the possibility of synthesizing ZnO-TiO2 mixed coatings by plasma electrochemical oxidation (PEO). The aim of the work was to synthesize TiO2-ZnO mixed coatings on a titanium substrate from an electrolyte containing ZnO nanoparticles (NPs) and to assess the parameters of PEO on the structure, chemical composition, and properties of the obtained oxide coatings. The PEO process was carried out under various current-voltage conditions using different signals: DC, DC pulse, and AC. In this work, optimal conditions for the PEO process were determined to obtain well-adhering oxide coatings with the highest possible content of ZnO. The structure and morphology of the resulting oxide coatings were investigated, and their chemical and phase composition was comprehensively examined (EDX, XRD, XPS, and GD-OES). In addition, their basic optical properties were assessed. It has been shown that in the PEO DC pulse process, it is possible to obtain oxide coatings characterized by a high degree of structure order, high ZnO content in the oxide coating (3.6 at.%, XPS), and prospective applications for photocatalytic purposes (3.12 eV).

Biocompatibility and Antibacterial Properties of ZnO-Incorporated Anodic Oxide Coatings on TiZrNb Alloy.

In a present paper, we demonstrate novel approach to form ceramic coatings with incorporated ZnO nanoparticles (NPs) on low modulus TiZrNb alloy with enhanced biocompatibility and antibacterial parameters. Plasma Electrolytic Oxidation (PEO) was used to integrate ZnO nanoparticles (average size 12-27 nm), mixed with Ca(H2PO2)2 aqueous solution into low modulus TiZrNb alloy surface. The TiZrNb alloys with integrated ZnO NPs successfully showed higher surface porosity and contact angle. XPS investigations showed presence of Ca ions and absence of phosphate ions in the PEO modified layer, what explains higher values of contact angle. Cell culture experiment (U2OS type) confirmed that the surface of as formed oxide-ZnO NPs demonstrated hydrophobic properties, what can affect primary cell attachment. Further investigations showed that Ca ions in the PEO coating stimulated proliferative activity of attached cells, resulting in competitive adhesion between cells and bacteria in clinical situation. Thus, high contact angle and integrated ZnO NPs prevent bacterial adhesion and considerably enhance the antibacterial property of TiZrNb alloys. A new anodic oxide coating with ZnO NPs could be successfully used for modification of low modulus alloys to decrease post-implantation complications.

Formation of a Bacteriostatic Surface on ZrNb Alloy via Anodization in a Solution Containing Cu Nanoparticles.

High strength, excellent corrosion resistance, high biocompatibility, osseointegration ability, and low bacteria adhesion are critical properties of metal implants. Additionally, the implant surface plays a critical role as the cell and bacteria host, and the development of a simultaneously antibacterial and biocompatible implant is still a crucial challenge. Copper nanoparticles (CuNPs) could be a promising alternative to silver in antibacterial surface engineering due to low cell toxicity. In our study, we assessed the biocompatibility and antibacterial properties of a PEO (plasma electrolytic oxidation) coating incorporated with CuNPs (Cu nanoparticles). The structural and chemical parameters of the CuNP and PEO coating were studied with TEM/SEM (Transmission Electron Microscopy/Scanning Electron Microscopy), EDX (Energy-Dispersive X-ray Dpectroscopy), and XRD (X-ray Diffraction) methods. Cell toxicity and bacteria adhesion tests were used to prove the surface safety and antibacterial properties. We can conclude that PEO on a ZrNb alloy in Ca-P solution with CuNPs formed a stable ceramic layer incorporated with Cu nanoparticles. The new surface provided better osteoblast adhesion in all time-points compared with the nontreated metal and showed medium grade antibacterial activities. PEO at 450 V provided better antibacterial properties that are recommended for further investigation.