Surface functionalization of anodized tantalum with Mn3O4 nanoparticles for effective corrosion protection in simulated inflammatory condition

Anodic Production and Characterization of Biomimetic Oxide Layers on Grade 4 Titanium for Medical Applications

Biomaterials are the basis for the development of medicine because they allow safe contact with a living organism. The aim of this work was to produce innovative oxide layers with a microporous structure on the surface of commercially pure titanium Grade 4 (CpTi G4) and to characterize their properties as drug carriers. The anodization of the CpTi G4 subjected to mechanical grinding and electrochemical polishing was carried out in a solution of 1M ethylene glycol with the addition of 40 g of ammonium fluoride at a voltage of 20 V for 2, 18, 24, and 48 h at room temperature. It was found that the longer the anodization time, the greater the number of pores formed on the CpTi G4 surface as revealed using the FE-SEM method, and the greater the surface roughness determined in profilometric tests. As the anodizing time increases, the amount of the drug in the form of gentamicin sulfate incorporated into the resulting pores decreases. The most favorable drug release kinetics profile determined via UV-VIS absorption spectroscopy was found for the CpTi G4 anodized for 2 h.

Review of Anodic Tantalum Oxide Nanostructures: From Morphological Design to Emerging Applications

Anodization of transition metals, particularly the valve metals (V, W, Ti, Ta, Hf, Nb, and Zr) and their alloys, has emerged as a powerful tool for controlling the morphology, purity, and thickness of oxide nanostructures. The present review is focused on the advances in the synthesis of micro/nanostructures of anodic tantalum oxides (ATO) in inorganic, organic, and mixed inorganic-organic type electrolytes with critically highlighting anodization parameters, such as applied voltage, current, time, and electrolyte temperature. Particularly, the growth of ATO nanostructures in fluoride containing electrolytes and their applications are briefly covered. The details of the current- or voltage-time transient and its relation to the growth of the anodic oxide films are presented systematically. The main discussion revolves around the incorporation of various electrolyte species into the surface of ATO structures and its effects on their physicochemical properties. The latest progress in understanding the growth mechanism of nanoporous/nanotubular ATO structures is outlined. Additionally, the impact of annealing temperature (ranging from 400-1000 °C) and atmosphere on the crystalline structure, morphology, impurity content, and physical properties of the ATOs is briefly described. The common modification methods, such as decorating with other transition metal/metal oxide, heteroatom doping, or generating defects in the ATO structures, are discussed. Besides, the review also covers the most promising applications of these materials in the fields of capacitors, supercapacitors, memristive devices, corrosion protection, photocatalysis, photoelectrochemical (PEC) water splitting, and biomaterials. Finally, future research directions for designing ATO-based nanomaterials and their utilities are indicated.

Fucoidan-hybrid hydroxyapatite nanoparticles promote the osteogenic differentiation of human periodontal ligament stem cells under inflammatory condition

Inflammation-related bone defects often lead to poor osteogenesis. Therefore, it is crucial to reduce the inflammation response and promote the osteogenic differentiation of stem/progenitor cells to revitalize bone physiology. Here, a kind of hybrid nano-hydroxyapatite was prepared using the confined phosphate ion release method with the participation of fucoidan, a marine-sourced polysaccharide with anti-inflammation property. The physicochemical analyses confirmed that the fucoidan hybrid nano-hydroxyapatite (FC/n-HA) showed fine needle-like architectures. With a higher amount of fucoidan, the crystal size and crystallinity of the FC/n-HA reduced while the liquid dispersibility was improved. Cell experiences showed that FC/n-HA had an optimal cytocompatibility at concentration of 50 μg/mL. Moreover, the lipopolysaccharide-induced cellular inflammatory model with PDLSCs was established and used to evaluate the anti-inflammatory and osteogenic properties. For the 1%FC/n-HA group, the expression levels of TNF-α and IL-1β were significantly reduced at 24 h, while the expression of alkaline phosphatase of PDLSCs was significantly promoted at days 3 and 7, and calcium precipitates was enhanced at 21 days. In this study, the FC/n-HA particles showed effective anti-inflammatory properties and facilitated osteogenic differentiation of PDLSCs, indicating which has potential application in treating bone defects associated with inflammation, such as periodontitis.

The MnO2/GelMA Composite Hydrogels Improve the ROS Microenvironment of Annulus Fibrosus Cells by Promoting the Antioxidant and Autophagy through the SIRT1/NRF2 Pathway

Intervertebral disc degeneration (IVDD) is a worldwide disease that causes low back pain and reduces quality of life. Biotherapeutic strategies based on tissue engineering alternatives, such as intervertebral disc scaffolds, supplemented by drug-targeted therapy have brought new hope for IVDD. In this study, to explore the role and mechanism of MnO2/GelMA composite hydrogels in alleviating IVDD, we prepared composite hydrogels with MnO2 and methacrylate gelatin (GelMA) and characterized them using compression testing and transmission electron microscopy (TEM). Annulus fibrosus cells (AFCs) were cultured in the composite hydrogels to verify biocompatibility by live/dead and cytoskeleton staining. Cell viability assays and a reactive oxygen species (ROS) probe were used to analyze the protective effect of the composite hydrogels under oxidative damage. To explore the mechanism of improving the microenvironment, we detected the expression levels of antioxidant and autophagy-related genes and proteins by qPCR and Western blotting. We found that the MnO2/GelMA composite hydrogels exhibited excellent biocompatibility and a porous structure, which promoted cell proliferation. The addition of MnO2 nanoparticles to GelMA cleared ROS in AFCs and induced the expression of antioxidant and cellular autophagy through the common SIRT1/NRF2 pathway. Therefore, the MnO2/GelMA composite hydrogels, which can improve the disc microenvironment through scavenging intracellular ROS and resisting oxidative damage, have great application prospects in the treatment of IVDD.

TiO2/PEG as smart anticorrosion and drug-eluting platforms in inflammatory conditions

The failure of a titanium implant is often attributed to inflammatory reactions following implantation. This study focuses on the synthesis of a polyethylene glycol (PEG) layer on porous titanium dioxide (TiO2) coatings using plasma electrolytic oxidation (PEO). This PEG layer serves as a foundation for a drug-eluting platform designed to respond to pH stimuli during inflammation. Betamethasone (BET), a widely used anti-inflammatory drug, was loaded onto the pH-responsive functional PEG layers. The application of the PEG-BET layer onto TiO2 coatings through the vacuum dip coating method resulted in a pH-sensitive sustained release of BET over a 30-day period. Notably, the release rates were 81% at pH 5.0 and 55% at pH 7.2. Electrochemical corrosion tests conducted in both normal and acidic inflammatory solutions demonstrated that duplex composite coatings offer superior protection compared to simple oxide coatings. In a pH 5.0 solution, corrosion current density measurements revealed values of 1.75 μA cm-2 (PEO/PEG-BET), 8.87 μA cm-2 (PEO), and 49.17 μA cm-2 (bare titanium). These results highlight the effectiveness of the PEO/PEG-BET layer in sealing pores within PEO coatings, subsequently reducing the infiltration of corrosive ions in inflammatory environments.

Li-Mg-Si bioceramics provide a dynamic immuno-modulatory and repair-supportive microenvironment for peripheral nerve regeneration

Biomaterials can modulate the local immune and repair-supportive microenvironments to promote peripheral nerve regeneration. Inorganic bioceramics have been widely used for regulating tissue regeneration and local immune response. However, little is known on whether inorganic bioceramics can have potential for enhancing peripheral nerve regeneration and what are the mechanisms underlying their actions. Here, the inorganic lithium-magnesium-silicon (Li-Mg-Si, LMS) bioceramics containing scaffolds are fabricated and characterized. The LMS-containing scaffolds had no cytotoxicity against rat Schwann cells (SCs), but promoted their migration and differentiation towards a remyelination state by up-regulating the expression of neurotrophic factors in a β-catenin-dependent manner. Furthermore, using single cell-sequencing, we showed that LMS-containing scaffolds promoted macrophage polarization towards the pro-regenerative M2-like cells, which subsequently facilitated the migration and differentiation of SCs. Moreover, implantation with the LMS-containing nerve guidance conduits (NGCs) increased the frequency of M2-like macrophage infiltration and enhanced nerve regeneration and motor functional recovery in a rat model of sciatic nerve injury. Collectively, these findings indicated that the inorganic LMS bioceramics offered a potential strategy for enhancing peripheral nerve regeneration by modulating the immune microenvironment and promoting SCs remyelination.

Low-energy production of a monolithic catalyst with MnCu-synergetic enhancement for catalytic oxidation of volatile organic compounds

Producing a low-cost catalyst by a low-cost method is one of the hottest topics in the field of catalytic oxidization of volatile organic compounds (VOCs). In this work, a catalyst formula with a low-energy requirement was optimized in the powdered state, and verified in the monolithic state. An effective MnCu catalyst was synthesized at a temperature as low as 200 °C. Removals were all bigger than 88% for toluene, ethyl acetate, hexane, formaldehyde, and cyclohexanone at a low temperature of 240 °C. The MnCu catalyst was then loaded on a honeycomb cordierite, which was also effective for toluene removal at 240 °C. After characterizations, active phases were Mn₃O₄/CuMn₂O₄ in both the powdered and monolithic catalysts. The enhanced activity was attributed to balanced distributions of low-valence Mn and Cu, as well as abundant surface oxygen vacancies. The obtained catalyst is produced by low energy and effective at low temperature, which suggests a perspective application.

Surface Modification of Bi2O3 Nanoparticles with Biotinylated β-Cyclodextrin as a Biocompatible Therapeutic Agent for Anticancer and Antimicrobial Applications

Bismuth oxide nanoparticles with appropriate surface chemistry exhibit many interesting properties that can be utilized in a variety of applications. This paper describes a new route to the surface modification of bismuth oxide nanoparticles (Bi₂O₃ NPs) using functionalized beta-Cyclodextrin (β-CD) as a biocompatible system. The synthesis of Bi₂O₃ NP was done using PVA (poly vinyl alcohol) as the reductant and the Steglich esterification procedure for the functionalization of β-CD with biotin. Ultimately, the Bi₂O₃ NPs are modified using this functionalized β-CD system. The particle size of the synthesized Bi₂O₃ NPs is found to be in the range of 12-16 nm. The modified biocompatible systems were characterized using different characterization techniques such as Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray powder diffraction (XRD) and Differential Scanning Calorimetric analysis (DSC). Additionally, the antibacterial and anticancerous effects of the surface-modified Bi₂O₃ NP system were also investigated.

Interaction of Ceramic Implant Materials with Immune System

The immuno-compatibility of implant materials is a key issue for both initial and long-term implant integration. Ceramic implants have several advantages that make them highly promising for long-term medical solutions. These beneficial characteristics include such things as the material availability, possibility to manufacture various shapes and surface structures, osteo-inductivity and osteo-conductivity, low level of corrosion and general biocompatibility. The immuno-compatibility of an implant essentially depends on the interaction with local resident immune cells and, first of all, macrophages. However, in the case of ceramics, these interactions are insufficiently understood and require intensive experimental examinations. Our review summarizes the state of the art in variants of ceramic implants: mechanical properties, different chemical modifications of the basic material, surface structures and modifications, implant shapes and porosity. We collected the available information about the interaction of ceramics with the immune system and highlighted the studies that reported ceramic-specific local or systemic effects on the immune system. We disclosed the gaps in knowledge and outlined the perspectives for the identification to ceramic-specific interactions with the immune system using advanced quantitative technologies. We discussed the approaches for ceramic implant modification and pointed out the need for data integration using mathematic modelling of the multiple ceramic implant characteristics and their contribution for long-term implant bio- and immuno-compatibility.

Electrochemical and biological characterization of Ti-Nb-Zr-Si alloy for orthopedic applications

The performance of current biomedical titanium alloys is limited by inflammatory and severe inflammatory conditions after implantation. In this study, a novel Ti-Nb-Zr-Si (TNZS) alloy was developed and compared with commercially pure titanium, and Ti-6Al-4V alloy. Electrochemical parameters of specimens were monitored during 1 h and 12 h immersion in phosphate buffered saline (PBS) as a normal, PBS/hydrogen peroxide (H₂O₂) as an inflammatory, and PBS/H₂O₂/albumin/lactate as a severe inflammatory media. The results showed an effect of the H₂O₂ in inflammatory condition and the synergistic behavior of H₂O₂, albumin, and lactate in severe inflammatory condition towards decreasing the corrosion resistance of titanium biomaterials. Electrochemical tests revealed a superior corrosion resistance of the TNZS in all conditions due to the presence of silicide phases. The developed TNZS was tested for subsequent cell culture investigation to understand its biocompatibility nature. It exhibited favorable cell-materials interactions in vitro compared with Ti-6Al-4V. The results suggest that TNZS alloy might be a competitive biomaterial for orthopedic applications.

Recent Advancements in Metallic Drug-Eluting Implants

Over the past decade, metallic drug-eluting implants have gained significance in orthopedic and dental applications for controlled drug release, specifically for preventing infection associated with implants. Recent studies showed that metallic implants loaded with drugs were substituted for conventional bare metal implants to achieve sustained and controlled drug release, resulting in a desired local therapeutic concentration. A number of secondary features can be provided by the incorporated active molecules, including the promotion of osteoconduction and angiogenesis, the inhibition of bacterial invasion, and the modulation of host body reaction. This paper reviews recent trends in the development of the metallic drug-eluting implants with various drug delivery systems in the past three years. There are various types of drug-eluting implants that have been developed to meet this purpose, depending on the drug or agents that have been loaded on them. These include anti-inflammatory drugs, antibiotics agents, growth factors, and anti-resorptive drugs.

Effect of PMMA sealing treatment on the corrosion behavior of plasma electrolytic oxidized titanium dental implants in fluoride-containing saliva solution

Titanium (Ti) and its alloys are widely used as dental implant materials because of their high mechanical properties, biocompatibility, and corrosion resistance. This research was undertaken to study the effect of polymethyl-methacrylate (PMMA) sealing layer on the corrosion performance of plasma electrolytic oxidation (PEO)-coated titanium-based dental implants in pure saliva and fluoride-containing saliva solutions. The phase structure, chemical composition, and microstructure of coatings were investigated via x-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy, respectively. The corrosion behavior of the samples was evaluated by open circuit potential, potentiodynamic polarization, and electrochemical impedance spectroscopy tests. The deposition of the PMMA layer on the PEO-coated Ti dental implants was found to effectively seal the micropores and microcracks of the TiO2 coatings and block corrosive ions’ penetration routes through the coating. Thereby, the results indicated that better corrosion performance was observed when the PMMA layer is applied on PEO-coated Ti dental implants than on the simple PEO coatings.