TiO2 nanorod arrays modified Ti substrates promote the adhesion, proliferation and osteogenic differentiation of human periodontal ligament stem cells

Hydrogel Coatings of Implants for Pathological Bone Repair

Hydrogels are well-suited for biomedical applications due to their numerous advantages, such as excellent bioactivity, versatile physical and chemical properties, and effective drug delivery capabilities. Recently, hydrogel coatings have developed to functionalize bone implants which are biologically inert and cannot withstand the complex bone tissue repair microenvironment. These coatings have shown promise in addressing unique and pressing medical needs. This review begins with the major functionalized performance and interfacial bonding strategy of hydrogel coatings, with a focus on the novel external field response properties of the hydrogel. Recent advances in the fabrication strategies of hydrogel coatings and their use in the treatment of pathologic bone regeneration are highlighted. Finally, challenges and emerging trends in the evolution and application of physiological environment-responsive and external electric field-responsive hydrogel coatings for bone implants are discussed.

Nanomaterials Modulating the Fate of Dental-Derived Mesenchymal Stem Cells Involved in Oral Tissue Reconstruction: A Systematic Review

The critical challenges in repairing oral soft and hard tissue defects are infection control and the recovery of functions. Compared to conventional tissue regeneration methods, nano-bioactive materials have become the optimal materials with excellent physicochemical properties and biocompatibility. Dental-derived mesenchymal stem cells (DMSCs) are a particular type of mesenchymal stromal cells (MSCs) with great potential in tissue regeneration and differentiation. This paper presents a review of the application of various nano-bioactive materials for the induction of differentiation of DMSCs in oral and maxillofacial restorations in recent years, outlining the characteristics of DMSCs, detailing the biological regulatory effects of various nano-materials on stem cells and summarizing the material-induced differentiation of DMSCs into multiple types of tissue-induced regeneration strategies. Nanomaterials are different and complementary to each other. These studies are helpful for the development of new nanoscientific research technology and the clinical transformation of tissue reconstruction technology and provide a theoretical basis for the application of nanomaterial-modified dental implants. We extensively searched for papers related to tissue engineering bioactive constructs based on MSCs and nanomaterials in the databases of PubMed, Medline, and Google Scholar, using keywords such as "mesenchymal stem cells", "nanotechnology", "biomaterials", "dentistry" and "tissue regeneration". From 2013 to 2023, we selected approximately 150 articles that align with our philosophy.

Antibacterial and anti-inflammatory effects of PGLa-loaded TiO2 nanotube arrays

Objectives: This study investigated the antimicrobial effect and anti-inflammatory activities of PGLa-loaded TiO₂ nanotube arrays (TiO₂ NTs) in osteoblast-like MG-63 cells. Methods: The surface morphology and roughness of three titanium (Ti) substrates (Ti, TiO₂ NTs, PGLa-loaded TiO₂ NTs) were evaluated by scanning electron microscopy (SEM) and atomic force microscope (AFM). The wettability of three titanium substrates was evaluated by contact angle. Biocompatibility of PGLa-loaded TiO₂ NTs were evaluated in MG-63 cells (cell adhesion, proliferation, cytoskeletal evaluation and alkaline phosphatase activity). Spread plate counting method was used to evaluate antibacterial abilities of the titanium substrates. The calcein AM/PI staining evaluated cell viability of MG-63 cells on the substrates with or without proinflammatory factors (TNF-α). Results: The average surface roughness of untreated Ti, TiO₂ NTs, PGLa-loaded TiO₂ NTs were found to be 135.8 ± 6.4 nm, 300.5 ± 10.5 nm, 348.9 ± 16.9 nm, respectively. The contact angle of the untreated Ti was 77.4° ± 6.6°. TiO₂ NTs displayed excellent wettability which of contact angle was 12.1° ± 2.9°. The contact angle of the PGLa-loaded TiO₂ NTs was 34.6° ± 4.9°. MG-63 cells on surface of PGLa-loaded TiO₂ NTs showed better cell adhesion, proliferation and osteogenic activity. The antibacterial rate of PGLa-loaded TiO₂ NTs group significantly increased (84.6% ± 5.5%, p < 0.05). The rate of dead cells on the surfaces of the PGLa-loaded TiO₂ NTs with TNF-α decreased significantly (4.49% ± 0.02, p < 0.01). Conclusion: PGLa-loaded TiO₂ NTs have multi-biofunctions including biocompatibility, antibacterial and anti-inflammatory properties.

Medical and Dental Applications of Titania Nanoparticles: An Overview

Currently, titanium oxide (TiO₂) nanoparticles are successfully employed in human food, drugs, cosmetics, advanced medicine, and dentistry because of their non-cytotoxic, non-allergic, and bio-compatible nature when used in direct close contact with the human body. These NPs are the most versatile oxides as a result of their acceptable chemical stability, lower cost, strong oxidation properties, high refractive index, and enhanced aesthetics. These NPs are fabricated by conventional (physical and chemical) methods and the latest biological methods (biological, green, and biological derivatives), with their advantages and disadvantages in this epoch. The significance of TiO₂ NPs as a medical material includes drug delivery release, cancer therapy, orthopedic implants, biosensors, instruments, and devices, whereas their significance as a dental biomaterial involves dentifrices, oral antibacterial disinfectants, whitening agents, and adhesives. In addition, TiO₂ NPs play an important role in orthodontics (wires and brackets), endodontics (sealers and obturating materials), maxillofacial surgeries (implants and bone plates), prosthodontics (veneers, crowns, bridges, and acrylic resin dentures), and restorative dentistry (GIC and composites).

Preparation of Microstructure Laser Ablation and Multiple Acid-Etching Composites on the Surfaces of Medical Titanium Alloy TC4 by Laser Ablation and Multiple Acid-Etching, and Study of Frictional Properties of the Processed Surfaces

In this paper, four array patterns were first designed by observing the structural features of the surface microstructures of pig bones and tree frog paws on the titanium alloy surface bionically. Then, the optimal parameters for laser processing were determined experimentally, and the optimized processing parameters were used to prepare micron-scale bumps on the titanium alloy surface and to investigate the relationship between the weaving height and the processing times. Finally, multiple acid etching was used to prepare nanoscale holes on the surface of the titanium alloy. It was found that the multiple acid etching could not only prepare nanoscale holes on the surface of the titanium alloy, but could also well eliminate the slag left on the surface of titanium alloy by laser ablation. Based on the above study, this paper also analyzed the effect of micro-nano structure on the friction properties of the titanium alloy surface from three aspects—theory, hardness test and friction coefficient test—and experimentally analyzed the effect of single-factor and multi-factor coupling of structural features on the friction properties of the titanium alloy surface. It was found that the optimal mean friction coefficient was 0.0902, corresponding to the characteristic values of 0.66 for the shape, 200 μm for the edge length and 60 μm for the height.

Applications of Titanium Dioxide Nanostructure in Stomatology

Breakthroughs in the field of nanotechnology, especially in nanochemistry and nanofabrication technologies, have been attracting much attention, and various nanomaterials have recently been developed for biomedical applications. Among these nanomaterials, nanoscale titanium dioxide (nano-TiO₂) has been widely valued in stomatology due to the fact of its excellent biocompatibility, antibacterial activity, and photocatalytic activity as well as its potential use for applications such as dental implant surface modification, tissue engineering and regenerative medicine, drug delivery carrier, dental material additives, and oral tumor diagnosis and treatment. However, the biosafety of nano-TiO₂ is controversial and has become a key constraint in the development of nano-TiO₂ applications in stomatology. Therefore, in this review, we summarize recent research regarding the applications of nano-TiO₂ in stomatology, with an emphasis on its performance characteristics in different fields, and evaluations of the biological security of nano-TiO₂ applications. In addition, we discuss the challenges, prospects, and future research directions regarding applications of nano-TiO₂ in stomatology that are significant and worthy of further exploration.

The Calcium Phosphate Modified Titanium Implant Combined With Platelet-Rich Plasma Treatment Promotes Implant Stabilization in an Osteoporotic Model

ABSTRACT

Osteoporosis as a kind of systemic bone metabolic disease has become one of the most prevalent diseases among the middle- and old-age, characterized with low bone mass and disruptive osseous microenvironment. The poor bone condition both in quantity and quality makes it daunting for osteoporotic patients who are submitted to dental implantation, joint replacement therapy, or orthopedic surgery. Since calcium phosphate (CaP) and platelet-rich plasma (PRP) treatment, all have improving the effect on bone regeneration. Inspired by this fact, the authors introduced a kind of novel implant with CaP modified surface by HPT (hydrothermal & pressure) treatment in this study. After producing, the authors tested its physicochemical properties through scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscope (XPS) and contact-angle measurement. Then the authors desired to investigate the effect of this CaP-modified implant on bone regeneration and stabilization maintenance combined with PRP treatment by establishing an osteoporotic rat model. After 3 months of surgery, the authors collected all the specimens and evaluated new bone formation by micro-computed tomography (micro-CT) analysis, biomechanical test, and histologic assessment. All the results in vivo experiment showed the CaP modified implant combined with PRP treatment could improve the osteoinductive effect under osteoporotic condition, leading to better maintenance for stabilization between bone and implant interface, which might be rendered as a promising clinical method for osteoporotic patients when they receive orthopedic surgeries.

Development of Biopolymeric Hybrid Scaffold-Based on AAc/GO/nHAp/TiO2 Nanocomposite for Bone Tissue Engineering: In-Vitro Analysis

Bone tissue engineering is an advanced field for treatment of fractured bones to restore/regulate biological functions. Biopolymeric/bioceramic-based hybrid nanocomposite scaffolds are potential biomaterials for bone tissue because of biodegradable and biocompatible characteristics. We report synthesis of nanocomposite based on acrylic acid (AAc)/guar gum (GG), nano-hydroxyapatite (HAp NPs), titanium nanoparticles (TiO2 NPs), and optimum graphene oxide (GO) amount via free radical polymerization method. Porous scaffolds were fabricated through freeze-drying technique and coated with silver sulphadiazine. Different techniques were used to investigate functional group, crystal structural properties, morphology/elemental properties, porosity, and mechanical properties of fabricated scaffolds. Results show that increasing amount of TiO2 in combination with optimized GO has improved physicochemical and microstructural properties, mechanical properties (compressive strength (2.96 to 13.31 MPa) and Young's modulus (39.56 to 300.81 MPa)), and porous properties (pore size (256.11 to 107.42 μm) and porosity (79.97 to 44.32%)). After 150 min, silver sulfadiazine release was found to be ~94.1%. In vitro assay of scaffolds also exhibited promising results against mouse pre-osteoblast (MC3T3-E1) cell lines. Hence, these fabricated scaffolds would be potential biomaterials for bone tissue engineering in biomedical engineering.

Ni and TiO2 nanoparticles cause adhesion and cytoskeletal changes in human osteoblasts

Titanium-based alloys have established a crucial role in implantology. As material deteriorates overtime, nanoparticles of TiO₂ and Ni are released. This study is focused on the impact of TiO₂ and Ni nanoparticles with size of 100 nm on cytoskeletal and adhesive changes in human physiological and osteoarthritic osteoblasts. The impact of nanoparticles with concentration of 1.5 ng/mL on actin and tubulin expression and gene expression of FAK and ICAM-1 was studied. The cell size and actin expression of physiological osteoblasts decreased in presence of Ni nanoparticles, while TiO₂ nanoparticles caused increase in cell size and actin expression. Both cell lines expressed more FAK as a response to TiO₂ nanoparticles. ICAM-1 gene was overexpressed in both cell lines as a reaction to both types of nanoparticles. The presented study shows a crucial role of Ni and TiO₂ nanoparticles in human osteoblast cytoskeletal and adhesive changes, especially connected with the osteoarthritic cells. Graphical abstract.

Micro/nanodevices for assessment and treatment in stomatology and ophthalmology

Micro/nanodevices have been widely applied for the real-time monitoring of intracellular activities and the delivery of exogenous substances in the past few years. This review focuses on miniaturized micro/nanodevices for assessment and treatment in stomatology and ophthalmology. We first summarize the recent progress in this field by examining the available materials and fabrication techniques, device design principles, mechanisms, and biosafety aspects of micro/nanodevices. Following a discussion of biochemical sensing technology from the cellular level to the tissue level for disease assessment, we then summarize the use of microneedles and other micro/nanodevices in the treatment of oral and ocular diseases and conditions, including oral cancer, eye wrinkles, keratitis, and infections. Along with the identified key challenges, this review concludes with future directions as a small fraction of vast opportunities, calling for joint efforts between clinicians and engineers with diverse backgrounds to help facilitate the rapid development of this burgeoning field in stomatology and ophthalmology.

Super-assembled core/shell fibrous frameworks with dual growth factors for in situ cementum-ligament-bone complex regeneration

The regeneration of periodontal tissue defects remains a clinical challenge due to its complex tissue structure (e.g. periodontal ligament, alveolar bone and cementum) and poor self-healing ability. In situ tissue engineering has emerged as a promising approach that combines frameworks with growth factors that are specifically chosen for the recruitment of endogenous stem cells to the site of injury and to evoke the innate regenerative potential of the body. Herein, a core/shell fibrous super-assembled framework (SAF)-based sequential growth factor delivery system is developed, in which basic fibroblast growth factor (bFGF) and bone morphogenetic protein-2 (BMP-2) are designed to release in a sequential manner to facilitate in situ regeneration of the cementum-ligament-bone complex. The in situ tissue engineering framework (iTE-framework) shows ameliorated physicochemical properties and improved hydrophilicity, with an initial burst release of bFGF in the first few days, followed by a slow and constant release of BMP-2 up to 4 weeks. The iTE-framework shows excellent biocompatibility, significantly promoting the proliferation, migration and osteogenic differentiation of human periodontal ligament stem cells (PDLSCs) in vitro. After implantation in rat periodontal defects, the iTE-framework effectively triggers the recruitment of mesenchymal stem cells (MSCs) to the defect site, significantly promotes the formation of new bones, and facilitates the regeneration of the periodontal ligament and cementum tissue in vivo. Therefore, this sequential delivery system provides a promising therapeutic strategy for cementum-ligament-bone complex regeneration.

Effect of the immune responses induced by implants in a integrated three-dimensional micro-nano topography on osseointegration

In order to explore the abilities of an integrated three-dimensional micro-nano topography in immunomodulation and promoting bone formation, present study focuses on the titanium sheets used in the micro-nano topography by treating them with the sandblasted, large-grit and acid-etched (SLA)and alkaline thermal reaction. Further, we characterized and obtained the surface morphology, roughness, and hydrophilicity of the titanium sheets. Moreover, we detected their in vitro cytocompatibility and cell proliferation as well. In addition, investigation was carried out for the immunomodulatory ability of the titanium sheets in a micro-nano topography by observing the expression of M1 (classical activated macrophage) and M2 (alternatively activated macrophage) type marker factors, inflammatory factors, and morphological changes of RAW264.7 cells cultured on the titanium sheets in different topographies. Through cell migration experiments and coculture, we observed the effects of different titanium sheet immune environments on osteoblast migration, extracellular matrix mineralization, and osteoblast gene expression. These results showed that the micro-nano topography constructed through SLA and alkaline thermal treatment improved the hydrophilicity and promoted the cell proliferation. Moreover, it promoted RAW264.7 cells to polarize as M2 phenotype, thereby leading to the anti-inflammatory effect of local microenvironments. This facilitated osteoblasts to secrete bone morphogenetic protein-2 (BMP2) and vascular endothelial growth factor. Nonetheless, these findings provided a theoretical basis for the molecular biological mechanism related to implants in a micro-nano topography which promoted the osteointegration while offering a meaningful theoretical basis for the clinical treatment of such implants.

Hydrothermally grown TiO2-nanorods on surface mechanical attrition treated Ti: Improved corrosion fatigue and osteogenesis

Current bioactive modifications of Ti-based materials for promoting osteogenesis often decrease corrosion fatigue strength (σ_cf) of the resultant implants, thereby shortening their service lifespan. To solve this issue and accelerate the osteogenesis process, in the present study, a TiO₂ nanorods (TNR)-arrayed coating was hydrothermally grown on optimal surface mechanical attrition treated (SMATed) titanium (S-Ti). The microstructure, bond integrity, residual stress distribution, and corrosion fatigue of TNR-coated S-Ti (TNR/S-Ti) and the response of macrophages and bone marrow-derived mesenchymal stem cells (BMSCs) to TNR/S-Ti were investigated and compared with those of mechanically polished Ti (P-Ti), S-Ti, and TNR-coated P-Ti (TNR/P-Ti). S-Ti showed a nanograined layer and an underlying grain-deformed region with residual compressive stress, which was sustained even when it was hydrothermally coated with TNR. TNR on S-Ti showed nanotopography, composition, and bond strength almost identical to those of P-Ti. While TNR/P-Ti showed a considerable decrease in σ_cf compared to P-Ti, TNR/S-Ti exhibited an improved σ_cf which was even higher than that of P-Ti. Biologically, TNR/S-Ti enhanced adhesion, differentiation, and mineralization of BMSCs, and it also promoted adhesion and M1-to-M2 transition of macrophages as compared to S-Ti and P-Ti. With rapid phenotype switch of macrophages, the level of proinflammatory cytokines decreased, while anti-inflammatory cytokines were upregulated. In co-culture conditions, the migration, differentiation, and mineralization of BMSCs were enhanced by increased level of secretion factors of macrophages on TNR/S-Ti. The modified structure accelerated bone apposition in rabbit femur and is expected to induce a favorable immune microenvironment to facilitate osseointegration earlier; it can also simultaneously improve corrosion fatigue resistance of Ti-based implants and thereby enhance their service life.

Biological reaction control using topography regulation of nanostructured titanium

The micro- and nanosize surface topography of dental implants has been shown to affect the growth of surrounding cells. In this study, standardized and controlled periodic nanopatterns were fabricated with nanosized surface roughness on titanium substrates, and their influence on bone marrow stromal cells investigated. Cell proliferation assays revealed that the bare substrate with a 1.7 nm surface roughness has lower hydrophilicity but higher proliferation ability than that with a 0.6 nm surface roughness. Further, with the latter substrate, directional cell growth was observed for line and groove patterns with a width of 100 nm and a height of 50 or 100 nm, but not for those with a height of 10 or 25 nm. With the smooth substrate, time-lapse microscopic analyses showed that more than 80% of the bone marrow cells on the line and groove pattern with a height of 100 nm grew and divided along the lines. As the nanosized grain structure controls the cell proliferation rate and the nanosized line and groove structure (50–100 nm) controls cell migration, division, and growth orientation, these standardized nanosized titanium structures can be used to elucidate the mechanisms by which surface topography regulates tissue responses to biomaterials.

Fabrication of Curcumin-Modified TiO2 Nanoarrays via Cyclodextrin Based Polymer Functional Coatings for Osteosarcoma Therapy

The incomplete removal of bone tumors leads to increased local recurrence and poor prognosis. To prevent ostoperative tumor recurrence and simultaneously repair surgery-caused bone defects, there is a need of great significance to develop implantable biomaterials possessing both cancer cell-killing ability and excellent bioactivity. In this work, a functionalized titanium-based implant is successfully fabricated by loading curcumin (CUR) onto cyclodextrin based polymer (pCD) modified titanium dioxide (TiO₂ ) nanorod arrays. Herein, a polydopamine (pDA) assisted film is implemented as a first coating layer onto the surface of the TiO₂ nanoarrays to guarantee the robust anchorage of the pCD. The pCD coating acts as a reservoir for CUR, allowing for efficient drug loading and sustained release of anticancer drugs. Studies show that the CUR-modified surfaces (TiO₂ /pDA/pCD/CUR) can significantly promote apoptosis of osteosarcoma cells in vitro by inducing mitochondrial dysfunction caused by the ROS overproduction, and meanwhile, effectively inhibit the tumor growth in vivo. Moreover, such functionalized implants with surface density of loaded CUR at 22.48 µg cm^-2 or lower support the attachment and proliferation of osteoblasts in vitro. These results successfully demonstrate that as-prepared TiO₂ /pDA/pCD/CUR constructs have combined anticancer performance and good biocompatibility, which has great promise for the surgical therapy of bone tumors.

Promoting osteoblasts responses in vitro and improving osteointegration in vivo through bioactive coating of nanosilicon nitride on polyetheretherketone

Objective

To enhance the bioactivity of polyetheretherketone (PEEK) while maintain its mechanical strengths.

Methods

Suspension coating and melt bonding.

Results

Silicon nitride (Si₃N₄, SN) coating lead to higher surface roughness, hydrophilicity and protein absorption; SN coating could slowly release Si ion into simulated body fluid (SBF), which caused weak alkaline of micro-environment owing to the slight dissolution of SN; SN coating resulted in the improvements of adhesion, proliferation, differentiation and gene expressions of MC3T3-E1 cells in vitro; SN coating of PEEK with bioactive SN coating (CSNPK) obviously promoted bone regeneration and osseointegration in vivo.

Conclusions

CSNPK with SN coating as bone implant might be a promising candidate for orthopedic implants.

The Translational Potential of this Article

The silicon nitride-coated polyetheretherketone (CSNPK) prepared in this article could induce MC3T3-E1 cells adhesion, proliferation and differentiation in vitro; it could also induce bone regeneration in bone defect in vivo, which indicate its good cytocompatibility and biocompatibility. If the raw materials are medical grade, and preparation process as well as production process of this article are further improved, it will have great translational potential.

Controlled Release of Naringin in GelMA-Incorporated Rutile Nanorod Films to Regulate Osteogenic Differentiation of Mesenchymal Stem Cells

Naringin, a Chinese herbal medicine, has been demonstrated to concentration-dependently promote osteogenic differentiation of mesenchymal stem cells (MSCs). However, it remains a challenge to load naringin on coatings for osteogenesis and further control the release kinetics. Here, we demonstrated that the release behavior of naringin on rutile nanorod films could be controlled by either mixing naringin with gelatin methacryloyl (GelMA) before spinning onto the films or soaking the obtained GelMA-incorporated films with the naringin solution to achieve the distinct degradation-type release and diffusion-type release, respectively. We further revealed that the naringin-loaded coatings facilitated adhesion, proliferation and late differentiation, and mineralization of MSCs. Our findings provided a novel strategy to engineer the coatings with controlled release of naringin and emphasized the bioactivity of naringin for the osteogenic differentiation of MSCs.

A wear-resistant TiO2 nanoceramic coating on titanium implants for visible-light photocatalytic removal of organic residues

An effective treatment for peri-implantitis is to completely remove all the bacterial deposits from the contaminated implants, especially the organic residues, to regain biocompatibility and re-osseointegration, but none of the conventional decontamination treatments has achieve this goal. The photocatalytic activity of TiO₂ coating on titanium implants to degrade organic contaminants has attracted researchers' attention recently. But a pure TiO₂ coating only responses to harmful ultraviolet light. Additionally, the poor coating mechanical properties are unable to protect the coating integrity versus initial mechanical decontamination. To address these issues, a unique TiO₂ nanoceramic coating was fabricated on titanium substrates through an innovative plasma electrolytic oxidation (PEO) based procedure, which showed a disordered layer with oxygen vacancies on the outmost part. As a result, the coating could decompose methylene blue, rhodamine B, and pre-adsorbed lipopolysaccharide (LPS) under visible light. Additionally, the coating showed two-fold higher hardness than untreated titanium and excellent wear resistance against steel decontamination instruments, which could be attributed to the specific micro-structure, including the densely packed nanocrystals and good metallurgical combination. Moreover, the in vitro response of MG63 cells confirmed that the coating had comparable biocompatibility and osteoconductivity to untreated titanium substrates. This study provides a unique coating technique as well as a photocatalytic cleaning strategy to enhance decontamination of titanium dental implants, which will favour the development of peri-implantitis treatments. STATEMENT OF SIGNIFICANCE: The treatment of peri-implantitis is based on the complete removal of bacterial deposits, especially the organic residues, but conventional decontamination treatments are hard to achieve it. The photocatalytic activity of TiO₂ coating on titanium implants to degrade organic contaminants provides a promising strategy for deeper decontamination, but its nonactivation to visible light and poor mechanical properties have limited its application. To address these issues, a unique TiO₂ nanoceramic coating was fabricated on titanium substrates based on plasma electrolytic oxidation. The coating showed enhanced visible-light photocatalytic activity, excellent wear resistance and satisfied biocompatibility. Based on this functional coating, it is promising to develop a more efficient strategy for deep decontamination of implant surface, which will favour the development of peri-implantitis treatments.

Nano-scale modification of titanium implant surfaces to enhance osseointegration

The main aim of this review study was to report the state of art on the nano-scale technological advancements of titanium implant surfaces to enhance the osseointegration process. Several methods of surface modification are chronologically described bridging ordinary methods (e.g. grit blasting and etching) and advanced physicochemical approaches such as 3D-laser texturing and biomimetic modification. Functionalization procedures by using proteins, peptides, and bioactive ceramics have provided an enhancement in wettability and bioactivity of implant surfaces. Furthermore, recent findings have revealed a combined beneficial effect of micro- and nano-scale modification and biomimetic functionalization of titanium surfaces. However, some technological developments of implant surfaces are not commercially available yet due to costs and a lack of clinical validation for such recent surfaces. Further in vitro and in vivo studies are required to endorse the use of enhanced biomimetic implant surfaces. STATEMENT OF SIGNIFICANCE: Grit-blasting followed by acid-etching is currently used for titanium implant modifications, although recent technological biomimetic physicochemical methods have revealed enhanced osteoconductive and anti-microbial outcomes. An improvement in wettability and bioactivity of titanium implant surfaces has been accomplished by combining micro and nano-scale modification and functionalization with protein, peptides, and bioactive compounds. Such morphological and chemical modification of the titanium surfaces induce the migration and differentiation of osteogenic cells followed by an enhancement of the mineral matrix formation that accelerate the osseointegration process. Additionally, the incorporation of bioactive molecules into the nanostructured surfaces is a promising strategy to avoid early and late implant failures induced by the biofilm accumulation.

The Fate of Osteoblast-Like MG-63 Cells on Pre-Infected Bactericidal Nanostructured Titanium Surfaces

Biomaterials that have been newly implanted inside the body are the substratum targets for a "race for the surface", in which bacterial cells compete against eukaryotic cells for the opportunity to colonize the surface. A victory by the former often results in biomaterial-associated infections, which can be a serious threat to patient health and can undermine the function and performance of the implant. Moreover, bacteria can often have a 'head start' if implant contamination has taken place either prior to or during the surgery. Current prevention and treatment strategies often rely on systemic antibiotic therapies, which are becoming increasingly ineffective due to a growing prevalence of antibiotic-resistant bacteria. Nanostructured surfaces that kill bacteria by physically rupturing bacterial cells upon contact have recently emerged as a promising solution for the mitigation of bacterial colonization of implants. Furthermore, these nanoscale features have been shown to enhance the adhesion and proliferation of eukaryotic cells, which is a key to, for example, the successful osseointegration of load-bearing titanium implants. The bactericidal activity and biocompatibility of such nanostructured surfaces are often, however, examined separately, and it is not clear to what extent bacterial cell-surface interactions would affect the subsequent outcomes of host-cell attachment and osseointegration processes. In this study, we investigated the ability of bactericidal nanostructured titanium surfaces to support the attachment and growth of osteoblast-like MG-63 human osteosarcoma cells, despite them having been pre-infected with pathogenic bacteria. MG-63 is a commonly used osteoblastic model to study bone cell viability, adhesion, and proliferation on the surfaces of load-bearing biomaterials, such as titanium. The nanostructured titanium surfaces used here were observed to kill the pathogenic bacteria, whilst simultaneously enhancing the growth of MG-63 cells in vitro when compared to that occurring on sterile, flat titanium surfaces. These results provide further evidence in support of nanostructured bactericidal surfaces being used as a strategy to help eukaryotic cells win the "race for the surface" against bacterial cells on implant materials.

Application of Antimicrobial Nanoparticles in Dentistry

Oral cavity incessantly encounters a plethora of microorganisms. Plaque biofilm-a major cause of caries, periodontitis and other dental diseases-is a complex community of bacteria or fungi that causes infection by protecting pathogenic microorganisms from external drug agents and escaping the host defense mechanisms. Antimicrobial nanoparticles are promising because of several advantages such as ultra-small sizes, large surface-area-to-mass ratio and special physical and chemical properties. To better summarize explorations of antimicrobial nanoparticles and provide directions for future studies, we present the following critical review. The keywords "nanoparticle," "anti-infective or antibacterial or antimicrobial" and "dentistry" were retrieved from Pubmed, Scopus, Embase and Web of Science databases in the last five years. A total of 172 articles met the requirements were included and discussed in this review. The results show that superior antibacterial properties of nanoparticle biomaterials bring broad prospects in the oral field. This review presents the development, applications and underneath mechanisms of antibacterial nanoparticles in dentistry including restorative dentistry, endodontics, implantology, orthodontics, dental prostheses and periodontal field.

The Morphology, Structure, Mechanical Properties and Biocompatibility of Nanotubular Titania Coatings before and after Autoclaving Process

The autoclaving process is one of the sterilization procedures of implantable devices. Therefore, it is important to assess the impact of hot steam at high pressure on the morphology, structure, and properties of implants modified by nanocomposite coatings. In our works, we focused on studies on amorphous titania nanotubes produced by titanium alloy (Ti6Al4V) electrochemical oxidation in the potential range 5⁻60 V. Half of the samples were drying in argon stream at room temperature, and the second ones were drying additionally with the use of immersion in acetone and drying at 396 K. Samples were subjected to autoclaving and after sterilization they were structurally and morphologically characterized using Raman spectroscopy, diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) and scanning electron microscopy (SEM). They were characterized in terms of wettability, mechanical properties, and biocompatibility. Obtained results proved that the autoclaving of amorphous titania nanotube coatings produced at lower potentials (5⁻15 V) does not affect their morphology and structure regardless of the drying method before autoclaving. Nanotubular coatings produced using higher potentials (20⁻60 V) require removal of adsorbed water particles from their surface. Otherwise, autoclaving leads to the destruction of the architecture of nanotubular coatings, which is associated with the changing of their mechanical and biointegration properties.

Progress in TiO2 nanotube coatings for biomedical applications: a review

Titanium dioxide nanotubes (TNTs) have drawn wide attention and been extensively applied in the field of biomedicine, due to their large specific surface area, good corrosion resistance, excellent biocompatibility, and enhanced bioactivity. This review describes the preparation of TNTs and the surface modification that entrust the nanotubes with better antibacterial property and enhanced osteoblast adhesion, proliferation, and differentiation. Considering the contact between TNTs' surface and surrounding tissues after implantation, the interactions between TNTs (with properties including their diameter, length, wettability, and crystalline phase) and proteins, platelets, bacteria, and cells are illustrated. The state of the art in the applications of TNTs in dentistry, orthopedic implants, and cardiovascular stents are introduced. In particular, the application of TNTs in biosensing has attracted much attention due to its ability for the rapid diagnosis of diseases. Finally, the difficulties and challenges in the practical application of TNTs are also discussed.