Application of PVD coatings in medical implantology for enhanced performance, biocompatibility, and quality of life

Physical vapor deposition (PVD) coating is a versatile and well-liked method for depositing thin films of materials onto surfaces in a range of industries. Due to their numerous functional and aesthetic benefits, PVD coatings are beneficial in several applications, from electronics and optics to automotive and medical equipment. PVD coating technology dramatically improves the effectiveness and quality of medical implants. PVD-coated medical implants improve osseointegration, lower wear and friction, increase corrosion resistance, and have antibacterial properties, which lead to better patient outcomes, fewer complications, and overall higher quality of life for people who need implantable medical devices. The essential concepts of PVD coating and the numerous deposition techniques and materials used are covered at the study's outset. The specific uses of PVD-coated medical implants are then highlighted, including those for orthopedic and dental implants and cardiovascular and neurosurgical devices. The review also emphasizes the critical contribution of PVD coatings to reducing wear and friction, improving corrosion resistance, augmenting biocompatibility, enhancing osseointegration, and aesthetic appeal. The challenges and prospects of PVD coating technologies were further addressed in this article. This review is invaluable for academics, doctors, and businesspeople interested in the beneficial combination of PVD coating and medical implantology.

Polydopamine-Functionalized Bacterial Cellulose as Hydrogel Scaffolds for Skin Tissue Engineering

Bacterial cellulose (BC) is a natural polysaccharide polymer hydrogel produced sustainably by the strain Gluconacetobacter hansenii under static conditions. Due to their biocompatibility, easy functionalization, and necessary physicochemical and mechanical properties, BC nanocomposites are attracting interest in therapeutic applications. In this study, we functionalized BC hydrogel with polydopamine (PDA) without toxic crosslinkers and used it in skin tissue engineering. The BC nanofibers in the hydrogel had a thickness of 77.8 ± 20.3 nm, and they could be used to produce hydrophilic, adhesive, and cytocompatible composite biomaterials for skin tissue engineering applications using PDA. Characterization techniques, namely Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and Raman spectroscopy, were performed to investigate the formation of polydopamine on the BC nanofibers. The XRD peaks for BC occur at 2θ = 14.65°, 16.69°, and 22.39°, which correspond to the planes of (100), (010), and (110) of cellulose type Iα. Raman spectroscopy confirmed the formation of PDA, as indicated by the presence of bands corresponding to the vibration of aromatic rings and aliphatic C-C and C-O stretching at 1336 and 1567 cm-1, respectively. FTIR confirmed the presence of peaks corresponding to PDA and BC in the BC/PDA hydrogel scaffolds at 3673, 3348, 2900, and 1052 cm-1, indicating the successful interaction of PDA with BC nanofibers, which was further corroborated by the SEM images. The tensile strength, swelling ratio, degradation, and surface wettability characteristics of the composite BC biomaterials were also investigated. The BC/PDA hydrogels with PDA-functionalized BC nanofibers demonstrated excellent tensile strength and water-wetting ability while maintaining the stability of the BC fibers. The enhanced cytocompatibility of the BC/PDA hydrogels was studied using the PrestoBlue assay. Culturing murine NIH/3T3 fibroblasts on BC/PDA hydrogels showed higher metabolic activity and enhanced proliferation. Additionally, it improved cell viability when using BC/PDA hydrogels. Thus, these BC/PDA composite biomaterials can be used as biocompatible natural alternatives to synthetic substitutes for skin tissue engineering and wound-dressing applications.

Surface Characterization of New β Ti-25Ta-Zr-Nb Alloys Modified by Micro-Arc Oxidation

The technique of surface modification using electrolytic oxidation, called micro-arc oxidation (MAO), has been used in altering the surface properties of titanium alloys for biomedical purposes, enhancing their characteristics as an implant (biocompatibility, corrosion, and wear resistance). The layer formed by the micro-arc oxidation process induces the formation of ceramic oxides, which can improve the corrosion resistance of titanium alloys from the elements in the substrate, enabling the incorporation of bioactive components such as calcium, phosphorus, and magnesium. This study aims to modify the surfaces of Ti-25Ta-10Zr-15Nb (TTZN1) and Ti-25Ta-20Zr-30Nb (TTZN2) alloys via micro-arc oxidation incorporating Ca, P, and Mg elements. The chemical composition results indicated that the MAO treatment was effective in incorporating the elements Ca (9.5 ± 0.4 %atm), P (5.7 ± 0.1 %atm), and Mg (1.1 ± 0.1 %atm), as well as the oxidized layer formed by micropores that increases the surface roughness (1160 nm for the MAO layer of TTZN1, 585 nm for the substrate of TTZN1, 1428 nm for the MAO layer of TTZN2, and 661 nm for the substrate of TTZN2). Regarding the phases formed, the films are amorphous, with low crystallinity (4 and 25% for TTZN2 and TTZN1, respectively). Small amounts of anatase, zirconia, and calcium carbonate were detected in the Ti-25Ta-10Zr-15Nb alloy.

Osteoblastic response to biomaterials surfaces: Extracellular matrix proteomic analysis

The cellular response to surfaces is mediated, among other factors, by the extracellular matrix (ECM). However, little is known about the ECM proteome during mineralization. Our objective was to compare the ECM composition formed by osteoblast on different materials surfaces with proteomic analysis. Three types of biomaterial surfaces (pure titanium, anodized titanium, and zirconia) were used. Osteoblasts (MC3T3 linage) cells were cultivated on the biomaterials for 7, 14, and 21 days with the osteogenic medium. For the proteomic analysis, the specimens were washed, decellularized, and the ECM was collected. The majority of the typical ECM proteins, out of a total of 24 proteins identified, was expressed and regulated equally on the three biomaterials tested. Alpha-1,4 glucan phosphorylase was found to be down-regulated on zirconia on the seventh day, while at the same time, glycogen phosphorylase brain form was up-regulated on anodized titanium, both when compared with pure titanium (ratio: 1.06 and 0.97, respectively). And after 14 days of culture, glycogen phosphorylase brain form was downregulated on zirconia when compared with pure titanium (ratio: 0.90), suggesting the influence of material surface roughness and chemical composition on energy metabolism. Proteins related to bone development like Transforming growth factor beta-3 and Fibroblast growth factor 8 were found exclusively on pure titanium on the 21st day. Altogether, our results show a possible influence of material surfaces on the composition of ECM.

Accelerated Bone Regeneration by MOF Modified Multifunctional Membranes through Enhancement of Osteogenic and Angiogenic Performance

Owing to the insufficient guidance of new bone formation in orthopedic and craniomaxillofacial surgery, construction of a guided bone regeneration membrane to support vascularized bone regeneration remains a challenge. Herein, an electrospun asymmetric double-layer polycaprolactone/collagen (PCL/Col) membrane modified by metal-organic framework (MOF) crystals is developed. The optimization of the PCL/Col weight ratio (1:1 and 1:1.5) enables the composite membrane with a balanced tensile strength (only fell by 49.9% in wet conditions) and a controlled degradation rate (completely degraded at 12 weeks). The MOF crystals can provide a pH-responsive release of Zn²⁺ ions. In vitro experiments indicate that the barrier layer functions to prevent the infiltration of fibrous connective tissue. The MOF crystal layer functions to enhance osteogenesis and angiogenesis in vitro. Using a rat calvarial defect model, the MOF crystals exhibit a sign of osteoinductivity along with blood vessel formation after 8 weeks post-surgery. Strikingly, when assessed in a chick chorioallantoic membrane model, the MOF modified membrane demonstrates a significant angiogenic response, which can be envisaged as its outstanding merits over the commercially Col membrane. Therefore, the MOF crystals represent an exciting biomaterial option, with neovascularization capacity for bone tissue engineering and regenerative medicine.

TiO2 bioactive implant surfaces doped with specific amount of Sr modulate mineralization

One of the main problems that remain in the implant industry is poor osseointegration due to bioinertness of implants. In order to promote bioactivity, calcium (Ca), phosphorus (P) and strontium (Sr) were incorporated into a TiO₂ porous layer produced by micro-arc oxidation. Ca and P as bioactive elements are already well reported in the literature, however, the knowledge of the effect of Sr is still limited. In the present work, the effect of various amounts of Sr was evaluated and the morphology, chemical composition and crystal structure of the oxide layer were investigated. Furthermore, in vitro studies were carried out using human osteoblast-like cells. The oxide layer formed showed a triplex structure, where higher incorporation of Sr increased Ca/P ratio, amount of rutile and promoted the formation of SrTiO₃ compound. Biological tests revealed that lower concentrations of Sr did not compromise initial cell adhesion neither viability and interestingly improved mineralization. However, higher concentration of Sr (and consequent higher amount of rutile) showed to induce collagen secretion but with compromised mineralization, possibly due to a delayed mineralization process or induced precipitation of deficient hydroxyapatite. Ca-P-TiO₂ porous layer with less concentration of Sr seems to be an ideal candidate for bone implants.

Drug Delivery Systems Based on Titania Nanotubes and Active Agents for Enhanced Osseointegration of Bone Implants

TiO2 nanotubes (TNTs) are attractive nanostructures for localized drug delivery. Owing to their excellent biocompatibility and physicochemical properties, numerous functionalizations of TNTs have been attempted for their use as therapeutic agent delivery platforms. In this review, we discuss the current advances in the applications of TNT-based delivery systems with an emphasis on the various functionalizations of TNTs for enhancing osteogenesis at the bone-implant interface and for preventing implant-related infection. Innovation of therapies for enhancing osteogenesis still represents a critical challenge in regeneration of bone defects. The overall concept focuses on the use of osteoconductive materials in combination with the use of osteoinductive or osteopromotive factors. In this context, we highlight the strategies for improving the functionality of TNTs, using five classes of bioactive agents: growth factors (GFs), statins, plant derived molecules, inorganic therapeutic ions/nanoparticles (NPs) and antimicrobial compounds.

Effects of calcium and phosphorus incorporation on the properties and bioactivity of TiO2 nanotubes

In this study, we investigate the formation of calcium and phosphorus-doped TiO₂ nanotubes, produced by potentiostatic anodization of Ti in viscous electrolyte-containing HF and Ca/P ions. Characterization of the produced oxide layer was conducted using scanning electron microscopy, glancing-angle X-ray diffraction, X-ray photoelectron spectroscopy, contact angle, and protein adsorption measurements. Adipose-derived stem cells were used to study material cytotoxicity, cell viability and proliferation, and cell morphology and growth. To evaluate the adipose-derived stem-cell differentiation, we investigated the expression of osteocalcin and osteopontin by cells as well as calcium mineralization. Results show that it was possible to produce a superhydrophilic titanium oxide nanotube layer with incorporation of Ca and P ions. The presence of Ca and P in the oxide layer not only improved the cell adhesion and proliferation but also stimulated the production of key marker proteins indicating differentiation of cells.

The effect of applied voltages on the structure, apatite-inducing ability and antibacterial ability of micro arc oxidation coating formed on titanium surface

The micro arc oxidation (MAO) coatings with different concentrations of Ca, P and Zn elements are successfully formed on the titanium substrate at the different applied voltages. After MAO treatment, the MAO coating exhibits the porous surface structure and composed of anatase and rutile TiO2 phases. Meanwhile, the average size and density of micro-pores on the MAO coatings have been modified via the adjusting the applied voltages. In addition, the contents of the incorporated elements such as Zn, Ca and P elements in the MAO coatings have been optimized. The bonding strength test results reveal that the MAO coating shows higher bonding strength, which is up to 45 ± 5 MPa. Compared to the pure Ti plate, the MAO coating formed at 350 and 400 V show good apatite-inducing ability. Meanwhile, the MAO coating containing Zn, Ca and P elements have better antibacterial ability for E.coli and S.aureus. Thus, the incorporation of Zn, Ca and P elements was an effective method to improve the antibacterial ability. Moreover, the concentrations of Zn, Ca and P elements could be adjusted with the changing of the applied voltages. As a result, the enhancement of the antibacterial ability on the MAO coating surfaces was depended on the comprehensive effect of the incorporated elements and the surface property of MAO coatings.

A review of nanostructured surfaces and materials for dental implants: surface coating, patterning and functionalization for improved performance

The emerging field of nanostructured implants has enormous scope in the areas of medical science and dental implants. Surface nanofeatures provide significant potential solutions to medical problems by the introduction of better biomaterials, improved implant design, and surface engineering techniques such as coating, patterning, functionalization and molecular grafting at the nanoscale. This review is of an interdisciplinary nature, addressing the history and development of dental implants and the emerging area of nanotechnology in dental implants. After a brief introduction to nanotechnology in dental implants and the main classes of dental implants, an overview of different types of nanomaterials (i.e. metals, metal oxides, ceramics, polymers and hydrides) used in dental implant together with their unique properties, the influence of elemental compositions, and surface morphologies and possible applications are presented from a chemical point of view. In the core of this review, the dental implant materials, physical and chemical fabrication techniques and the role of nanotechnology in achieving ideal dental implants have been discussed. Finally, the critical parameters in dental implant design and available data on the current dental implant surfaces that use nanotopography in clinical dentistry have been discussed.