The enhanced characteristics of osteoblast adhesion to photofunctionalized nanoscale TiO2 layers on biomaterials surfaces

Beyond microroughness: novel approaches to navigate osteoblast activity on implant surfaces

Considering the biological activity of osteoblasts is crucial when devising new approaches to enhance the osseointegration of implant surfaces, as their behavior profoundly influences clinical outcomes. An established inverse correlation exists between osteoblast proliferation and their functional differentiation, which constrains the rapid generation of a significant amount of bone. Examining the surface morphology of implants reveals that roughened titanium surfaces facilitate rapid but thin bone formation, whereas smooth, machined surfaces promote greater volumes of bone formation albeit at a slower pace. Consequently, osteoblasts differentiate faster on roughened surfaces but at the expense of proliferation speed. Moreover, the attachment and initial spreading behavior of osteoblasts are notably compromised on microrough surfaces. This review delves into our current understanding and recent advances in nanonodular texturing, meso-scale texturing, and UV photofunctionalization as potential strategies to address the "biological dilemma" of osteoblast kinetics, aiming to improve the quality and quantity of osseointegration. We discuss how these topographical and physicochemical strategies effectively mitigate and even overcome the dichotomy of osteoblast behavior and the biological challenges posed by microrough surfaces. Indeed, surfaces modified with these strategies exhibit enhanced recruitment, attachment, spread, and proliferation of osteoblasts compared to smooth surfaces, while maintaining or amplifying the inherent advantage of cell differentiation. These technology platforms suggest promising avenues for the development of future implants.

Optimizing implant osseointegration, soft tissue responses, and bacterial inhibition: A comprehensive narrative review on the multifaceted approach of the UV photofunctionalization of titanium

Titanium implants have revolutionized restorative and reconstructive therapy, yet achieving optimal osseointegration and ensuring long-term implant success remain persistent challenges. In this review, we explore a cutting-edge approach to enhancing implant properties: ultraviolet (UV) photofunctionalization. By harnessing UV energy, photofunctionalization rejuvenates aging implants, leveraging and often surpassing the intrinsic potential of titanium materials. The primary aim of this narrative review is to offer an updated perspective on the advancements made in the field, providing a comprehensive overview of recent findings and exploring the relationship between UV-induced physicochemical alterations and cellular responses. There is now compelling evidence of significant transformations in titanium surface chemistry induced by photofunctionalization, transitioning from hydrocarbon-rich to carbon pellicle-free surfaces, generating superhydrophilic surfaces, and modulating the electrostatic properties. These changes are closely associated with improved cellular attachment, spreading, proliferation, differentiation, and, ultimately, osseointegration. Additionally, we discuss clinical studies demonstrating the efficacy of UV photofunctionalization in accelerating and enhancing the osseointegration of dental implants. Furthermore, we delve into recent advancements, including the development of one-minute vacuum UV (VUV) photofunctionalization, which addresses the limitations of conventional UV methods as well as the newly discovered functions of photofunctionalization in modulating soft tissue and bacterial interfaces. By elucidating the intricate relationship between surface science and biology, this body of research lays the groundwork for innovative strategies aimed at enhancing the clinical performance of titanium implants, marking a new era in implantology.

Advanced Antimicrobial and Anti-Infective Strategies to Manage Peri-Implant Infection: A Narrative Review

Despite reductions in bacterial infection and enhanced success rate, the widespread use of systemic antibiotic prophylaxis in implant dentistry is controversial. This use has contributed to the growing problem of antimicrobial resistance, along with creating significant health and economic burdens. The basic mechanisms that cause implant infection can be targeted by new prevention and treatment methods which can also lead to the reduction of systemic antibiotic exposure and its associated adverse effects. This review aims to summarize advanced biomaterial strategies applied to implant components based on anti-pathogenic mechanisms and immune balance mechanisms. It emphasizes that modifying the dental implant surface and regulating the early immune response are promising strategies, which may further prevent or slow the development of peri-implant infection, and subsequent failure.

Vacuum Ultraviolet (VUV) Light Photofunctionalization to Induce Human Oral Fibroblast Transmigration on Zirconia

Soft tissue adhesion and sealing around dental and maxillofacial implants, related prosthetic components, and crowns are a clinical imperative to prevent adverse outcomes of periodontitis and periimplantitis. Zirconia is often used to fabricate implant components and crowns. Here, we hypothesized that UV treatment of zirconia would induce unique behaviors in fibroblasts that favor the establishment of a soft tissue seal. Human oral fibroblasts were cultured on zirconia specimens to confluency before placing a second zirconia specimen (either untreated or treated with one minute of 172 nm vacuum UV (VUV) light) next to the first specimen separated by a gap of 150 µm. After seven days of culture, fibroblasts only transmigrated onto VUV-treated zirconia, forming a 2.36 mm volume zone and 5.30 mm leading edge. Cells migrating on VUV-treated zirconia were enlarged, with robust formation of multidirectional cytoplastic projections, even on day seven. Fibroblasts were also cultured on horizontally placed and 45° and 60° tilted zirconia specimens, with the latter configurations compromising initial attachment and proliferation. However, VUV treatment of zirconia mitigated the negative impact of tilting, with higher tilt angles increasing the difference in cellular behavior between control and VUV-treated specimens. Fibroblast size, perimeter, and diameter on day seven were greater than on day one exclusively on VUV-treated zirconia. VUV treatment reduced surface elemental carbon and induced superhydrophilicity, confirming the removal of the hydrocarbon pellicle. Similar effects of VUV treatment were observed on glazed zirconia specimens with silica surfaces. One-minute VUV photofunctionalization of zirconia and silica therefore promotes human oral fibroblast attachment and proliferation, especially under challenging culture conditions, and induces specimen-to-specimen transmigration and sustainable photofunctionalization for at least seven days.

Optimization of blood and protein flow around superhydrophilic implant surfaces by promoting contact hemodynamics

PURPOSE

We examined blood and protein dynamics potentially influenced by implant threads and hydrophilic/hydrophobic states of implant surfaces.

METHODS

A computational fluid dynamics model was created for a screw-shaped implant with a water contact angle of 70° (hydrophobic surface) and 0° (superhydrophilic surface). Movements and density of blood and fibrinogen as a representative wound healing protein were visualized and quantified during constant blood inflow.

RESULTS

Blood plasma did not occupy 40-50% of the implant interface or the inside of threads around hydrophobic implants, whereas such blood voids were nearly completely eliminated around superhydrophilic implants. Whole blood field vectors were disorganized and random within hydrophobic threads but formed vortex nodes surrounded by stable blood streams along the superhydrophilic implant surface. The averaged vector within threads was away from the implant surface for the hydrophobic implant and towards the implant surface for the superhydrophilic implant. Rapid and massive whole blood influx into the thread zone was only seen for the superhydrophilic implant, whereas a line of conflicting vectors formed at the entrance of the thread area of the hydrophobic implant to prevent blood influx. The fibrinogen density was up to 20-times greater at the superhydrophilic implant interface than the hydrophobic one. Fibrinogen density was higher at the interface than outside the threads only for the superhydrophilic implant.

CONCLUSIONS

Implant threads and surface hydrophilicity have profound effects on vector and distribution of blood and proteins. Critically, implant threads formed significant biological voids at the interface that were negated by superhydrophilicity-induced contact hemodynamics.

Laser-Modified Ti Surface Improves Paracrine Osteogenesis by Modulating the Expression of DKK1 in Osteoblasts

Titanium surface modifications are widely used to modulate cellular behavior by recognition of topographical cues. However, how those modifications affect the expression of mediators that will influence neighboring cells is still elusive. This study aimed to evaluate the effects of conditioned media from osteoblasts cultured on laser-modified titanium surfaces on the differentiation of bone marrow cells in a paracrine manner and to analyze the expression of Wnt pathway inhibitors. Mice calvarial osteoblasts were seeded on polished (P) and Yb:YAG laser-irradiated (L) Ti surfaces. Osteoblast culture media were collected and filtered on alternate days to stimulate mice BMCs. Resazurin assay was performed every other day for 20 days to check BMC viability and proliferation. After 7 and 14 days of BMCs maintained with osteoblasts P and L-conditioned media, alkaline phosphatase activity, Alizarin Red staining, and RT-qPCR were performed. ELISA of conditioned media was conducted to investigate the expression of Wnt inhibitors Dickkopf-1 (DKK1) and Sclerostin (SOST). BMCs showed increased mineralized nodule formation and alkaline phosphatase activity. The L-conditioned media enhanced the BMC mRNA expression of bone-related markers Bglap, Alpl, and Sp7. L-conditioned media decreased the expression of DKK1 compared with P-conditioned media. The contact of osteoblasts with Yb:YAG laser-modified Ti surfaces induces the regulation of the expression of mediators that affect the osteoblastic differentiation of neighboring cells. DKK1 is among these regulated mediators.

A Novel High-Energy Vacuum Ultraviolet Light Photofunctionalization Approach for Decomposing Organic Molecules around Titanium

Titanium undergoes biological aging, represented by increased hydrophobicity and surface accumulation of organic molecules over time, which compromises the osseointegration of dental and orthopedic implants. Here, we evaluated the efficacy of a novel UV light source, 172 nm wavelength vacuum UV (VUV), in decomposing organic molecules around titanium. Methylene blue solution used as a model organic molecule placed in a quartz ampoule with and without titanium specimens was treated with four different UV light sources: (i) ultraviolet C (UVC), (ii) high-energy UVC (HUVC), (iii) proprietary UV (PUV), and (iv) VUV. After one minute of treatment, VUV decomposed over 90% of methylene blue, while there was 3-, 3-, and 8-fold more methylene blue after the HUVC, PUV, and UVC treatments, respectively. In dose-dependency experiments, maximal methylene blue decomposition occurred after one minute of VUV treatment and after 20-30 min of UVC treatment. Rapid and effective VUV-mediated organic decomposition was not influenced by the surface topography of titanium or its alloy and even occurred in the absence of titanium, indicating only a minimal photocatalytic contribution of titanium dioxide to organic decomposition. VUV-mediated but not other light source-mediated methylene blue decomposition was proportional to its concentration. Plastic tubes significantly reduced methylene blue decomposition for all light sources. These results suggest that VUV, in synergy with quartz ampoules, mediates rapid and effective organic decomposition compared with other UV sources. This proof-of-concept study paves the way for rapid and effective VUV-powered photofunctionalization of titanium to overcome biological aging.

Decomposing Organic Molecules on Titanium with Vacuum Ultraviolet Light for Effective and Rapid Photofunctionalization

Ultraviolet (UV) photofunctionalization counteracts the biological aging of titanium to increase the bioactivity and osseointegration of titanium implants. However, UV photofunctionalization currently requires long treatment times of between 12 min and 48 h, precluding routine clinical use. Here, we tested the ability of a novel, xenon excimer lamp emitting 172 nm vacuum UV (VUV) to decompose organic molecules coated on titanium as a surrogate of photofunctionalization. Methylene blue as a model organic molecule was coated on grade 4 commercially pure titanium and treated with four UV light sources: (i) ultraviolet C (UVC), (ii) high-energy UVC (HUVC), (iii) proprietary UV (PUV), and (iv) VUV. After one minute of treatment, VUV decomposed 57% of methylene blue compared with 2%, 36%, and 42% for UVC, HUVC, and PUV, respectively. UV dose-dependency testing revealed maximal methylene blue decomposition with VUV within one minute. Equivalent decomposition was observed on grade 5 titanium alloy specimens, and placing titanium specimens in quartz ampoules did not compromise efficacy. Methylene blue was decomposed even on polymethyl methacrylate acrylic specimens at 20-25% lower efficiency than on titanium specimens, indicating a relatively small contribution of titanium dioxide-mediated photocatalytic decomposition to the total decomposition. Load-testing revealed that VUV maintained high efficacy of methylene blue decomposition regardless of the coating density, whereas other UV light sources showed low efficacy with thin coatings and plateauing efficacy with thicker coatings. This study provides foundational data on rapid and efficient VUV-mediated organic decomposition on titanium. In synergy with quartz ampoules used as containers, VUV has the potential to overcome current technical challenges hampering the clinical application of UV photofunctionalization.

Ultraviolet Light Treatment of Titanium Microfiber Scaffolds Enhances Osteoblast Recruitment and Osteoconductivity in a Vertical Bone Augmentation Model: 3D UV Photofunctionalization

Vertical bone augmentation to create host bone prior to implant placement is one of the most challenging regenerative procedures. The objective of this study is to evaluate the capacity of a UV-photofunctionalized titanium microfiber scaffold to recruit osteoblasts, generate intra-scaffold bone, and integrate with host bone in a vertical augmentation model with unidirectional, limited blood supply. Scaffolds were fabricated by molding and sintering grade 1 commercially pure titanium microfibers (20 μm diameter) and treated with UVC light (200-280 nm wavelength) emitted from a low-pressure mercury lamp for 20 min immediately before experiments. The scaffolds had an even and dense fiber network with 87% porosity and 20-50 mm inter-fiber distance. Surface carbon reduced from 30% on untreated scaffold to 10% after UV treatment, which corresponded to hydro-repellent to superhydrophilic conversion. Vertical infiltration testing revealed that UV-treated scaffolds absorbed 4-, 14-, and 15-times more blood, water, and glycerol than untreated scaffolds, respectively. In vitro, four-times more osteoblasts attached to UV-treated scaffolds than untreated scaffolds three hours after seeding. On day 2, there were 70% more osteoblasts on UV-treated scaffolds. Fluorescent microscopy visualized confluent osteoblasts on UV-treated microfibers two days after seeding but sparse and separated cells on untreated microfibers. Alkaline phosphatase activity and osteocalcin gene expression were significantly greater in osteoblasts grown on UV-treated microfiber scaffolds. In an in vivo model of vertical augmentation on rat femoral cortical bone, the interfacial strength between innate cortical bone and UV-treated microfiber scaffold after two weeks of healing was double that observed between bone and untreated scaffold. Morphological and chemical analysis confirmed seamless integration of the innate cortical and regenerated bone within microfiber networks for UV-treated scaffolds. These results indicate synergy between titanium microfiber scaffolds and UV photofunctionalization to provide a novel and effective strategy for vertical bone augmentation.

A Novel Cell Delivery System Exploiting Synergy between Fresh Titanium and Fibronectin

Delivering and retaining cells in areas of interest is an ongoing challenge in tissue engineering. Here we introduce a novel approach to fabricate osteoblast-loaded titanium suitable for cell delivery for bone integration, regeneration, and engineering. We hypothesized that titanium age influences the efficiency of protein adsorption and cell loading onto titanium surfaces. Fresh (newly machined) and 1-month-old (aged) commercial grade 4 titanium disks were prepared. Fresh titanium surfaces were hydrophilic, whereas aged surfaces were hydrophobic. Twice the amount of type 1 collagen and fibronectin adsorbed to fresh titanium surfaces than aged titanium surfaces after a short incubation period of three hours, and 2.5-times more fibronectin than collagen adsorbed regardless of titanium age. Rat bone marrow-derived osteoblasts were incubated on protein-adsorbed titanium surfaces for three hours, and osteoblast loading was most efficient on fresh titanium adsorbed with fibronectin. The number of osteoblasts loaded using this synergy between fresh titanium and fibronectin was nine times greater than that on aged titanium with no protein adsorption. The loaded cells were confirmed to be firmly attached and functional. The number of loaded cells was strongly correlated with the amount of protein adsorbed regardless of the protein type, with fibronectin simply more efficiently adsorbed on titanium surfaces than collagen. The role of surface hydrophilicity of fresh titanium surfaces in increasing protein adsorption or cell loading was unclear. The hydrophilicity of protein-adsorbed titanium increased with the amount of protein but was not the primary determinant of cell loading. In conclusion, the osteoblast loading efficiency was dependent on the age of the titanium and the amount of protein adsorption. In addition, the efficiency of protein adsorption was specific to the protein, with fibronectin being much more efficient than collagen. This is a novel strategy to effectively deliver osteoblasts ex vivo and in vivo using titanium as a vehicle.

TiO2 Nanocoatings with Controllable Crystal Type and Nanoscale Topography on Zirconia Implants to Accelerate Bone Formation

In dentistry, zirconia implants have emerged as a promising alternative for replacing missing teeth due to their superior aesthetic performance and chemical stability. To improve the osseointegration of zirconia implants, modifying their surface with hierarchical micro/nanotopography and bioactive chemical composition are two effective ways. In this work, a microscale topography was prepared on a zirconia surface using hydrofluoric acid etching, and then a 50 nm TiO₂ nanocoating was deposited via atomic layer deposition (ALD). Subsequently, an annealing treatment was used to transform the TiO₂ from amorphous to anatase and simultaneously generate nanoscale topography. Various investigations into the coating surface morphology, topography, wettability, and chemical composition were carried out using scanning electron microscopy, white light interferometry, contact-angle measurement, X-ray diffraction, and X-ray photoelectron spectroscopy. In addition, in vitro cytocompatibility and osteogenic potential performance of the coatings were evaluated by human bone marrow mesenchymal stem cells (hBMSCs), and in vivo osseointegration performance was assessed in a rat femoral condyle model. Moreover, the possible mechanism was also investigated. The deposition of TiO₂ film with/without annealing treatment did not alter the microscale roughness of the zirconia surface, whereas the nanotopography changed significantly after annealing. The in vitro studies revealed that the anatase TiO₂ coating with regular wavelike nanostructure could promote the adhesion and proliferation of osteoblasts and further improve the osteogenic potential in vitro and osseointegration in vivo. These positive effects may be caused by nanoscale topography via the canonical Wnt/β-catenin pathway. The results suggest that using ALD in combination with annealing treatment to fabricate a nanotopographic TiO₂ coating is a promising way to improve the osteogenic properties of zirconia implants.

Osteoblast Attachment Compromised by High and Low Temperature of Titanium and Its Restoration by UV Photofunctionalization

Titanium implants undergo temperature fluctuations during manufacturing, transport, and storage. However, it is unknown how this affects their bioactivity. Herein, we explored how storage (six months, dark conditions) and temperature fluctuations (5-50 °C) affected the bioactivity of titanium implants. Stored and fresh acid-etched titanium disks were exposed to different temperatures for 30 min under wet or dry conditions, and their hydrophilicity/hydrophobicity and bioactivity (using osteoblasts derived from rat bone marrow) were evaluated. Ultraviolet (UV) treatment was evaluated as a method of restoring the bioactivity. The fresh samples were superhydrophilic after holding at 5 or 25 °C under wet or dry conditions, and hydrophilic after holding at 50 °C. In contrast, all the stored samples were hydrophobic. For both fresh and stored samples, exposure to 5 or 50 °C reduced osteoblast attachment compared to holding at 25 °C under both wet and dry conditions. Regression analysis indicated that holding at 31 °C would maximize cell attachment (p < 0.05). After UV treatment, cell attachment was the same or better than that before temperature fluctuations. Overall, titanium surfaces may have lower bioactivity when the temperature fluctuates by ≥20 °C (particularly toward lower temperatures), independent of the hydrophilicity/hydrophobicity. UV treatment was effective in restoring the temperature-compromised bioactivity.

A rapid quantitation of cell attachment and spreading based on digital image analysis: Application for cell affinity and compatibility assessment of synthetic polymers

Accurate and rapid quantitation of cell attachment, spreading, and growth on a polymer thin film coated glass cover slide was developed by analyzing the digital images of cells stained with dyes. A biodegradable block copolymer poly(ethylene glycol)-block-poly(l-lactide-co-2-methyl-2-carboxyl-propylene carbonate) [PEG-b-P(LA-co-MCC)] was synthesized as model polymer with poly(L-lactic acid) [PLLA] as a control polymer. Only a small quantity of polymer (~5 mg) was needed in this method through dissolving in a solvent and casting on cover slides which were previously modified with dimethyl dichlorosilane (DMDC). Then it was seeded with cells and taken pictures with a digital camera under an optical microscope and analyzed with ImageJ software. Cell number and a series of morphological data were obtained, including cell area, circularity, perimeter and Feret's diameter, etc. The quantitative analysis results indicated that cells preferred to attach and spread on the surface of the copolymer PEG-b-P(LA-co-MCC) compared to PLLA during 24 h of cell culture. This efficient procedure provides a series of convincing statistical data to evaluate the direct interaction between cells and polymers with only an optical microscope, a digital camera and ImageJ software. It's a rapid, economic way for assessing cell affinity and compatibility of novel synthetic polymers by cell culture in vitro.

Dissecting the Inorganic Nanoparticle-Driven Interferences on Adhesome Dynamics

Inorganic nanoparticles have emerged as an attractive theranostic tool applied to different pathologies such as cancer. However, the increment in inorganic nanoparticle application in biomedicine has prompted the scientific community to assess their potential toxicities, often preventing them from entering clinical settings. Cytoskeleton network and the related adhesomes nest are present in most cellular processes such as proliferation, migration, and cell death. The nanoparticle treatment can interfere with the cytoskeleton and adhesome dynamics, thus inflicting cellular damage. Therefore, it is crucial dissecting the molecular mechanisms involved in nanoparticle cytotoxicity. This review will briefly address the main characteristics of different adhesion structures and focus on the most relevant effects of inorganic nanoparticles with biomedical potential on cellular adhesome dynamics. Besides, the review put into perspective the use of inorganic nanoparticles for cytoskeleton targeting or study as a versatile tool. The dissection of the molecular mechanisms involved in the nanoparticle-driven interference of adhesome dynamics will facilitate the future development of nanotheranostics targeting cytoskeleton and adhesomes to tackle several diseases, such as cancer.

Surface treatment of 3D printed porous Ti6Al4V implants by ultraviolet photofunctionalization for improved osseointegration

Three-dimensional (3D)-printed porous Ti6Al4V implants play an important role in the reconstruction of bone defects. However, its osseointegration capacity needs to be further improved, and related methods are inadequate, especially lacking customized surface treatment technology. Consequently, we aimed to design an omnidirectional radiator based on ultraviolet (UV) photofunctionalization for the surface treatment of 3D-printed porous Ti6Al4V implants, and studied its osseointegration promotion effects in vitro and in vivo, while elucidating related mechanisms. Following UV treatment, the porous Ti6Al4V scaffolds exhibited significantly improved hydrophilicity, cytocompatibility, and alkaline phosphatase activity, while preserving their original mechanical properties. The increased osteointegration strength was further proven using a rabbit condyle defect model in vivo, in which UV treatment exhibited a high efficiency in the osteointegration enhancement of porous Ti6Al4V scaffolds by increasing bone ingrowth (BI), the bone-implant contact ratio (BICR), and the mineralized/osteoid bone ratio. The advantages of UV treatment for 3D-printed porous Ti6Al4V implants using the omnidirectional radiator in the study were as follows: 1) it can significantly improve the osseointegration capacity of porous titanium implants despite the blocking out of UV rays by the porous structure; 2) it can evenly treat the surface of porous implants while preserving their original topography or other morphological features; and 3) it is an easy-to-operate low-cost process, making it worthy of wide clinical application.

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An omnidirectional radiator based on ultraviolet photofunctionalization was invented..

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The omnidirectional radiator can evenly treat the surface of the porous implants..

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The present method can enhance osteoinetegration of porous Ti6Al4V implants in a convenient way with a low cost.

Influence of surface modification of titanium implants on improving osseointegration: An in vitro study

STATEMENT OF PROBLEM

The effect of aging and the surface treatment of implants on osseointegration needs to be evaluated.

PURPOSE

The purpose of this in vitro study was to evaluate the effects of aging and the surface treatment of titanium with ultraviolet (UV) radiation and fibroblast growth factor (FGF) on hydrophilicity and cell growth and thus on osseointegration.

MATERIAL AND METHODS

A total of 28 specimens were divided into 2 groups to measure hydrophilicity (n=14) and cell growth (n=14). Each group was further divided into 4 groups according to surface modification. These include the control group (CG) (nascent specimens), aged group (AG) (nascent specimens aged for 4 weeks), photofunctionalized group (PG) (aged specimens UV-A treated), and mimed group (MG) (aged specimens UV-A and FGF2 treated). The PG and MG specimens were treated with UV-A light for 40 minutes. The biomimetic surface modification was performed for MG. Hydrophilicity was measured by using the contact angle in relation to the surface of titanium disks with the help of a drop shape analyzing device (KRUSS), and cell growth was measured by calculating the number of stem cells per cm² with the help of a scanning electron microscope (SEM). The data obtained were subjected to statistical analysis with a statistical software program (α=.05).

RESULTS

The lowest contact angle values were found in PG (13.52 ±0.90 degrees) and the highest in AG (70.54 ±1.72 degrees). The highest number of cells per cm² (2880 ±99.33) were found for MG, and the lowest number of cells per cm² (760 ±9.17) for AG.

CONCLUSIONS

Aging decreased the hydrophilicity and cell adhesion, migration, and growth on the titanium surface. UV treatment improved the hydrophilicity, cell adhesion, migration, and growth for both CG and AG. FGF2 treatment increased the cell adhesion, migration, and growth for CG, AG, and PG.

Utilization of Antibacterial Nanoparticles in Photocurable Additive Manufacturing of Advanced Composites for Improved Public Health

This paper presents the additive manufacturing and characterization of nanoparticle-reinforced photocurable resin-based nanocomposites with a potential antimicrobial function for improved public health applications. Two types of photocurable resins are reinforced by titanium dioxide (TiO₂) or zinc oxide (ZnO) nanoparticles with average diameters in the 10-30 nm range to provide antimicrobial properties. The developed nanocomposites can be additively manufactured using the digital light processing method with an outstanding surface quality and precise geometrical accuracy. Experimental characterizations are conducted to investigate key mechanical properties of the 3D printed nanocomposites, including Young's Modulus, tensile strength, and abrasion resistance. Specimens produced were observed to demonstrate the following characteristics during testing. Tensile strength increased by 42.2% at a maximum value of 29.53 MPa. The modulus of elasticity increased by 14.3%, and abrasion resistance increased by 15.8%. The proper dispersion of the nanoparticles within the cured resin is validated by scanning electron images. The wettability and water absorption testing results indicate that the developed nanocomposites have an outstanding water resistance capability. The pairing of digital light processing with these novel nanocomposites allows for the creation of complex composite geometries that are not capable through other manufacturing processes. Therefore, they have the potential for long-term usage to improve general public health with antimicrobial functionality. The pairing of an unmodified photocurable resin with a 1% ZnO concentration demonstrated the most promise for commercial applications.

Biomimetic Zirconia with Cactus-Inspired Meso-Scale Spikes and Nano-Trabeculae for Enhanced Bone Integration

Biomimetic design provides novel opportunities for enhancing and functionalizing biomaterials. Here we created a zirconia surface with cactus-inspired meso-scale spikes and bone-inspired nano-scale trabecular architecture and examined its biological activity in bone generation and integration. Crisscrossing laser etching successfully engraved 60 μm wide, cactus-inspired spikes on yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) with 200–300 nm trabecular bone-inspired interwoven structures on the entire surface. The height of the spikes was varied from 20 to 80 μm for optimization. Average roughness (Sa) increased from 0.10 μm (polished smooth surface) to 18.14 μm (80 μm-high spikes), while the surface area increased by up to 4.43 times. The measured dimensions of the spikes almost perfectly correlated with their estimated dimensions (R² = 0.998). The dimensional error of forming the architecture was 1% as a coefficient of variation. Bone marrow-derived osteoblasts were cultured on a polished surface and on meso- and nano-scale hybrid textured surfaces with different spike heights. The osteoblastic differentiation was significantly promoted on the hybrid-textured surfaces compared with the polished surface, and among them the hybrid-textured surface with 40 μm-high spikes showed unparalleled performance. In vivo bone-implant integration also peaked when the hybrid-textured surface had 40 μm-high spikes. The relationships between the spike height and measures of osteoblast differentiation and the strength of bone and implant integration were non-linear. The controllable creation of meso- and nano-scale hybrid biomimetic surfaces established in this study may provide a novel technological platform and design strategy for future development of biomaterial surfaces to improve bone integration and regeneration.

UV Light-Generated Superhydrophilicity of a Titanium Surface Enhances the Transfer, Diffusion and Adsorption of Osteogenic Factors from a Collagen Sponge

It is a significant challenge for a titanium implant, which is a bio-inert material, to recruit osteogenic factors, such as osteoblasts, proteins and blood effectively when these are contained in a biomaterial. The objective of this study was to examine the effect of ultraviolet (UV)-treatment of titanium on surface wettability and the recruitment of osteogenic factors when they are contained in an atelocollagen sponge. UV treatment of a dental implant made of commercially pure titanium was performed with UV-light for 12 min immediately prior to the experiments. Superhydrophilicity on dental implant surfaces was generated with UV-treatment. The collagen sponge containing blood, osteoblasts, or albumin was directly placed on the dental implant. Untreated implants absorbed only a little blood from the collagen sponge, while the UV-treated implants absorbed blood rapidly and allowed it to spread widely, almost over the entire implant surface. Blood coverage was 3.5 times greater for the UV-treated implants (p < 0.001). Only 6% of the osteoblasts transferred from the collagen sponge to the untreated implants, whereas 16% of the osteoblasts transferred to the UV-treated implants (p < 0.001). In addition, a weight ratio between transferred albumin on the implant and measured albumin adsorbed on the implant was 17.3% in untreated implants and 38.5% in UV-treated implants (p < 0.05). These results indicated that UV treatment converts a titanium surface into a superhydrophilic and bio-active material, which could recruite osteogenic factors even when they were contained in a collagen sponge. The transfer and subsequent diffusion and adsorption efficacy of UV-treated titanium surfaces could be useful for bone formation when titanium surfaces and osteogenic factors are intervened with a biomaterial.

Cell-friendly photo-functionalized TiO2 nano-micro-honeycombs for selectively preventing bacteria and platelet adhesion

Titanium dioxide (TiO₂) is a widely used biomaterial. It is a great challenge to confer antibacterial and antithrombotic properties to TiO₂ while maintaining its cell affinity. Here, we developed a new strategy to achieve the above goal by comprehensively controlling the chemical cues and geometrical cues of the surface of TiO₂. Using colloidal etching technology and UV irradiation treatment, we obtained the photofunctionalized nano-micro-honeycomb structured TiO₂. The honeycomb structured increased the photocatalytic activity of TiO₂, which endowed TiO₂ with photo-induced superhydrophilicity to inhibit bacterial adhesion. The high photocatalytic activity also induced the strong photocatalytic oxidation of TiO₂ surface organic adsorbates to suppress fibrinogen and platelet attachment. In addition, owing to the micropore trapping-isolation effect on the bacteria and the nano-frames' contact guidance effect on the growth and spreading of platelet pseudopods, the honeycomb structure also shows a considerable inhibiting effect on bacterial and platelet adhesion. Therefore, due to the controlled chemical and geometrical cues' synergistic effect, the photo-functionalized TiO₂ honeycomb structure shows excellent bacterial-adhesion resistance and antithrombotic properties. More importantly, the photo-functionalized TiO₂ honeycomb did not inhibit the adhesion and growth of endothelial cells (ECs) after culturing for 3 d, indicating a good cell affinity that the traditional antifouling surfaces do not possess.

Outlining cell interaction and inflammatory cytokines on UV-photofunctionalized mixed-phase TiO2 thin film

Photofunctionalization mediated by ultraviolet (UV) light seems to be a promising approach to improve the physico-chemical characteristics and the biological response of titanium (Ti) dental implants. Seeing that photofunctionalization is able to remove carbon from the surface, besides to promote reactions on the titanium dioxide (TiO₂) layer, coating the Ti with a stable TiO₂ film could potentialize the UV effect. Thus, here we determined the impact of UV-photofunctionalized mixed-phase (anatase and rutile) TiO₂ films on the physico-chemical properties of Ti substrate and cell biology. Mixed-phase TiO₂ films were grown by radiofrequency magnetron sputtering on commercially pure titanium (cpTi) discs, and samples were divided as follow: cpTi (negative control), TiO₂ (positive control), cpTi UV, TiO₂ UV (experimental). Photofunctionalization was performed using UVA (360 nm - 40 W) and UVC (250 nm - 40 W) lamps for 48 h. Surfaces were analyzed in terms of morphology, topography, chemical composition, crystalline phase, wettability and surface free energy. Pre-osteoblastic cells (MC3T3E1) were used to assess cell morphology and adhesion, metabolism, mineralization potential and cytokine secretion (IFN-γ, TNF-α, IL-4, IL-6 and IL-17). TiO₂-coated surfaces exhibited granular surface morphology and greater roughness. Photofunctionalization increased wettability (p < 0.05) and surface free energy (p < 0.001) on both surface conditions. TiO₂-treated groups featured normal cell morphology and spreading, and greater cellular metabolic activity at 2 and 4 days (p < 0.05), whereas UV-photofunctionalized surfaces enhanced cell metabolism, cell adhered area, and calcium deposition (day 14) (p < 0.05). In general, assessed proteins were found slightly affected by either UV or TiO₂ treatments. Altogether, our findings suggest that UV-photofunctionalized TiO₂ surface has the potential to improve pre-osteoblastic cell differentiation and the ability of cells to form mineral nodules by modifying Ti physico-chemical properties towards a more stable context. UV-modified surfaces modulate the secretion of key inflammatory markers.

Decontamination of Ti Oxide Surfaces by Using Ultraviolet Light: Hg-Vapor vs. LED-Based Irradiation

C-range Ultraviolet (UVC) mercury (Hg)-vapor lamps have shown the successful decontamination of hydrocarbons and antimicrobial effects from titanium surfaces. This study focused on surface chemistry modifications of titanium dental implants by using two different light sources, Hg-vapor lamps and Light Emitting Diodes (LEDs), so as to compare the effectivity of both photofunctionalization technologies. Two different devices, a small Hg-vapor lamp (λ = 254 nm) and a pair of closely placed LEDs (λ = 278 nm), were used to irradiate the implants for 12 min. X-ray Photoelectron Spectroscopy (XPS) was employed to characterize the chemical composition of the surfaces, analysing the samples before and after the lighting treatment, performing a wide and narrow scan around the energy peaks of carbon, oxygen and titanium. XPS analysis showed a reduction in the concentration of surface hydrocarbons in both UVC technologies from around 26 to 23.4 C at.% (carbon atomic concentration). Besides, simultaneously, an increase in concentration of oxygen and titanium was observed. LED-based UVC photofunctionalization has been suggested to be as effective a method as Hg-vapor lamps to remove the hydrocarbons from the surface of titanium dental implants. Therefore, due to the increase in worldwide mercury limitations, LED-based technology could be a good alternative decontamination source.

Ultraviolet Radiant Energy-Dependent Functionalization Regulates Cellular Behavior on Titanium Dioxide Nanodots

Titanium dioxide (TiO₂) photofunctionalization has been demonstrated as an effective surface modification method for the osseointegration of implants. However, the insufficient understanding of the mechanism underlying photofunctionalization limits its clinical applications. Here, we report an ultraviolet (UV) radiant energy-dependent functionalization on TiO₂ nanodots (TN) surfaces. We found the cell adhesion, proliferation, and osteogenic differentiation gradually increased with the accumulation of UV radiant energy (URE). The optimal functionalizing treatment energy was found to be 2000 mJ/cm², which could regulate cell-specific behaviors on TN surfaces. The enhanced cell behaviors were regulated by the adsorption and functional site exposure of the extracellular matrix (ECM) proteins, which were the result of the surface physicochemical changes induced by the URE. The correlation between the URE and the reconstruction of surface hydroxyl groups was considered as an alternative mechanism of this energy-dependent functionalization. We also demonstrated the synergistic effects of FAK-RHOA and ERK1/2 signaling pathways on mediating the URE-dependent cell behaviors. Overall, this study provides a novel insight into the mechanisms of photofunctionalization, guiding the design of implants and the clinical practice of photofunctionalization.

Bioinspired Fabrication of Calcium-Doped TiP Coating with Nanofibrous Microstructure to Accelerate Osseointegration

Bioinspired by the morphology of osteoclast-resorbed bone surfaces, we prepared a calcium-doped titanium phosphate (Ca-TiP) coating, which consists of a nanofibrous network, on titanium (Ti) substrate via a simple two-step hydrothermal method, trying to mimic natural bone compositionally and microstructurally. The in vitro studies show that the Ca-TiP coating with synergistic features of nanofibrous biomimetic topography and surface chemistry could elicit intensively osteogenic behavior and responses including enhanced cell adhesion, spreading, and proliferation as well as alkaline phosphatase (ALP) activity and up-regulated expression of bone-related genes, which inevitably benefit the formation of new bone and the quality of osseointegration. When the two control groups are compared in vivo, the significantly improved new bone formation in the early stage and the much stronger interfacial bonding with the surrounding bone for Ca-TiP coating suggest that Ca-TiP coating modified Ti implants hold great potential for orthopedic and dental applications.

Novel Osteogenic Behaviors around Hydrophilic and Radical-Free 4-META/MMA-TBB: Implications of an Osseointegrating Bone Cement

Poly(methyl methacrylate) (PMMA)-based bone cement, which is widely used to affix orthopedic metallic implants, is considered bio-tolerant but lacks osteoconductivity and is cytotoxic. Implant loosening and toxic complications are significant and recognized problems. Here we devised two strategies to improve PMMA-based bone cement: (1) adding 4-methacryloyloxylethyl trimellitate anhydride (4-META) to MMA monomer to render it hydrophilic; and (2) using tri-n-butyl borane (TBB) as a polymerization initiator instead of benzoyl peroxide (BPO) to reduce free radical production. Rat bone marrow-derived osteoblasts were cultured on PMMA-BPO, common bone cement ingredients, and 4-META/MMA-TBB, newly formulated ingredients. After 24 h of incubation, more cells survived on 4-META/MMA-TBB than on PMMA-BPO. The mineralized area was 20-times greater on 4-META/MMA-TBB than PMMA-BPO at the later culture stage and was accompanied by upregulated osteogenic gene expression. The strength of bone-to-cement integration in rat femurs was 4- and 7-times greater for 4-META/MMA-TBB than PMMA-BPO during early- and late-stage healing, respectively. MicroCT and histomorphometric analyses revealed contact osteogenesis exclusively around 4-META/MMA-TBB, with minimal soft tissue interposition. Hydrophilicity of 4-META/MMA-TBB was sustained for 24 h, particularly under wet conditions, whereas PMMA-BPO was hydrophobic immediately after mixing and was unaffected by time or condition. Electron spin resonance (ESR) spectroscopy revealed that the free radical production for 4-META/MMA-TBB was 1/10 to 1/20 that of PMMA-BPO within 24 h, and the substantial difference persisted for at least 10 days. The compromised ability of PMMA-BPO in recruiting cells was substantially alleviated by adding free radical-scavenging amino-acid N-acetyl cysteine (NAC) into the material, whereas adding NAC did not affect the ability of 4-META/MMA-TBB. These results suggest that 4-META/MMA-TBB shows significantly reduced cytotoxicity compared to PMMA-BPO and induces osteoconductivity due to uniquely created hydrophilic and radical-free interface. Further pre-clinical and clinical validations are warranted.

A nitrogen-containing bisphosphonate inhibits osteoblast attachment and impairs bone healing in bone-compatible scaffold

Compromised osteoblast attachment on hydroxyapatite could be involved in the development of bone healing failure. We developed a bone-compatible scaffold that mimics bone structure with sub-micron hydroxyapatite (HA) surfaces, so that we could evaluate the effects of nitrogen-containing bisphosphonate (N-BP) on osteoblast behavior and bone healing. Human osteoblasts were seeded onto the bone-compatible scaffold with or without N-BP, and cell attachment and spreading behavior were evaluated 4 and 24 h after seeding. Then, mineralization was evaluated at 7 and 14 days. The osteoconductive activity of the scaffold was evaluated by implantation for 3 and 6 weeks into a rat cranial bone defect. The numbers of osteoblasts and their diameters were significantly less in N-BP-binding scaffolds than in untreated scaffolds at 4 and 24 h. Mineralization were also significantly less in the N-BP-binding scaffolds than in controls at 7 and 14 days. In vivo study revealed bone formation in N-BP-binding scaffolds was significantly less than in untreated scaffolds at 3 and 6 weeks. These results suggest that N-BP-binding to HA inhibited osteoblast attachment and spreading, thereby compromising bone healing process in the injured bone defect site.

Biological and physicochemical implications of the aging process on titanium and zirconia implant material surfaces

STATEMENT OF PROBLEM

Changes in physicochemical properties because of implant material aging and natural deterioration in the oral environment can facilitate microbial colonization and disturb the soft-tissue seal between the implant surfaces.

PURPOSE

The purpose of this in vitro study was to investigate the effect of aging time on the physicochemical profile of titanium (Ti) and zirconia (ZrO₂) implant materials. Further microbiology and cell analyses were used to provide insights into the physicochemical implications of biological behavior.

MATERIAL AND METHODS

Disk-shaped specimens of Ti and ZrO₂ were submitted to roughness, morphology, and surface free energy (SFE) analyses before nonaging (NA) and after the aging process (A). To simulate natural aging, disks were subjected to low-temperature degradation (LTD) by using an autoclave at 134 ºC and 0.2 MPa pressure for 20 hours. The biological activities of the Ti and ZrO₂ surfaces were determined by analyzing Candida albicans (C. albicans) biofilms and human gingival fibroblast (HGF) cell proliferation. For the microbiology assays, a variance analysis method (ANOVA) was used with the Tukey post hoc test. For the evaluation of cellular proliferation, the Kruskal-Wallis test followed by Dunn multiple comparisons were used.

RESULTS

Ti nonaging (TNA) and ZrO₂ nonaging (ZNA) disks displayed hydrophilic and lipophilic properties, and this effect was sustained after the aging process. Low-temperature degradation resulted in a modest change in intermolecular interaction, with 1.06-fold for TA and 1.10-fold for ZA. No difference in biofilm formation was observed between NA and A disks of the same material. After 48 hours, the viability of the attached HGF cells was very similar to that in the NA and A groups, regardless of the tested material.

CONCLUSION

The changes in the physicochemical properties of Ti and ZrO₂ induced by the aging process do not interfere with C. albicans biofilm formation and HGF cell attachment, even after long-term exposure.

Tuning of Titanium Microfiber Scaffold with UV-Photofunctionalization for Enhanced Osteoblast Affinity and Function

Titanium (Ti) is an osteoconductive material that is routinely used as a bulk implant to fix and restore bones and teeth. This study explored the effective use of Ti as a bone engineering scaffold. Challenges to overcome were: (1) difficult liquid/cell infiltration into Ti microfiber scaffolds due to the hydrophobic nature of Ti; and (2) difficult cell attachment on thin and curved Ti microfibers. A recent discovery of UV-photofunctionalization of Ti prompted us to examine its effect on Ti microfiber scaffolds. Scaffolds in disk form were made by weaving grade 4 pure Ti microfibers (125 µm diameter) and half of them were acid-etched to roughen the surface. Some of the scaffolds with original or acid-etched surfaces were further treated by UV light before cell culture. Ti microfiber scaffolds, regardless of the surface type, were hydrophobic and did not allow glycerol/water liquid to infiltrate, whereas, after UV treatment, the scaffolds became hydrophilic and immediately absorbed the liquid. Osteogenic cells from two different origins, derived from the femoral and mandibular bone marrow of rats, were cultured on the scaffolds. The number of cells attached to scaffolds during the early stage of culture within 24 h was 3–10 times greater when the scaffolds were treated with UV. The development of cytoplasmic projections and cytoskeletal, as well as the expression of focal adhesion protein, were exclusively observed on UV-treated scaffolds. Osteoblastic functional phenotypes, such as alkaline phosphatase activity and calcium mineralization, were 2–15 times greater on UV-treated scaffolds, with more pronounced enhancement on acid-etched scaffolds compared to that on the original scaffolds. These effects of UV treatment were associated with a significant reduction in atomic carbon on the Ti microfiber surfaces. In conclusion, UV treatment of Ti microfiber scaffolds tunes their physicochemical properties and effectively enhances the attachment and function of osteoblasts, proposing a new strategy for bone engineering.

Biocorrosion of pure and SLA titanium surfaces in the presence of Porphyromonas gingivalis and its effects on osteoblast behavior

Objective: The study aims to investigate the biocorrosion behavior of Porphyromonas gingivalis on pure and SLA titanium surfaces and its effects on surface characteristics and osteoblast behavior. Methods: Pure and SLA titanium specimens were immersed in culture medium with P. gingivalis and incubated for 7 days. P. gingivalis colonization on the pure and SLA titanium surfaces was observed by scanning electron microscopy (SEM). The pure and SLA titanium surface characteristics were analyzed via X-ray photoelectron spectroscopy (XPS), surface roughness and surface wettability. The corrosion behaviors of pure and SLA titanium specimens were evaluated by electrochemical corrosion test. The osteoblast behavior of MC3T3-E1 cells on the pure and SLA titanium surfaces after P. gingivalis colonization was investigated by cell adhesion and western blot assays. Results: P. gingivalis colonized on the pure and SLA titanium surfaces was observed by SEM. The XPS analysis demonstrated reductions in the relative levels of titanium and oxygen and obvious reductions of dominant titanium dioxide (TiO₂) on both titanium surfaces after immersing the metal in P. gingivalis culture. In addition, their roughness and wettability were changed. Correspondingly, the electrochemical corrosion test results revealed significant decreases in the corrosion resistance and increases in the corrosion rate of the pure and SLA titanium specimens after immersion in P. gingivalis culture. The results of the in vitro study showed that the pre-corroded pure and SLA titanium surfaces by P. gingivalis exhibited lower osteocompatibility and down-regulated the adhesion, spreading and osteogenic differentiation abilities of MC3T3-E1 cells. Conclusions: P. gingivalis was able to colonize on the pure and SLA titanium surfaces and weaken their surface properties, especially a decrease in the protective TiO₂ film, which induced the biocorrosion and further negatively affected the osteoblast behavior.

The study demonstrated that P. gingivalis could colonize on pure and SLA titanium surfaces and weaken their surface properties, especially the protective TiO₂ film, which induced the biocorrosion and further negatively affected osteoblast behavior.

Biomaterial-based possibilities for managing peri-implantitis

Peri‐implantitis is an inflammatory disease of hard and soft tissues around osseointegrated implants, followed by a progressive damage of alveolar bone. Oral microorganisms can adhere to all types of surfaces by the production of multiple adhesive factors. Inherent properties of materials will influence not only the number of microorganisms, but also their profile and adhesion force onto the material surface. In this perspective, strategies to reduce the adhesion of pathogenic microorganisms on dental implants and their components should be investigated in modern rehabilitation concepts in implant dentistry. To date, several metallic nanoparticle films have been developed to reduce the growth of pathogenic bacteria. However, the main drawback in these approaches is the potential toxicity and accumulative effect of the metals over time. In view of biological issues and in attempt to prevent and/or treat peri‐implantitis, biomaterials as carriers of antimicrobial substances have attracted special attention for application as coatings on dental implant devices. This review will focus on biomaterial‐based possibilities to prevent and/or treat peri‐implantitis by describing concepts and dental implant components suitable for engagement in preventing and treating this disease. Additionally, we raise important criteria referring to the geometric parameters of dental implants and their components, which can directly affect peri‐implant tissue conditions. Finally, we overview currently available biomaterial systems that can be used in the field of oral implantology.

Ultraviolet A and Ultraviolet C Light-Induced Reduction of Surface Hydrocarbons on Titanium Implants

Objective The carbon, titanium, and oxygen levels on titanium implant surfaces with or without ultraviolet (UV) pretreatment were evaluated at different wavelengths through X-ray photoelectron spectroscopy (XPS).

Materials and Methods This interventional experimental study was conducted on nine Dio UFII implants with hybrid sandblasted and acid-etched (SLA) surface treatments, divided equally into three groups. Control group A samples were not given UV irradiation, while groups B and C samples were given UVA (382 nm, 25 mWcm ² ) and UVC (260 nm, 15 mWcm ² ) irradiation, respectively. The atomic ratio of carbon, titanium, and oxygen was compared through XPS.

Results Mean carbon-to-titanium ratio and C1 peaks considerably increased in Group A compared to those in experimental Groups B and C. The intensity of Ti2p and O1s peaks was more pronounced for group C compared to that for groups A and B.

Conclusions Although the decrease in surface hydrocarbons was the same in both UV-treated groups, the peak intensity of oxygen increased in the UVC-treated group. Thus, it can be concluded that compared with UVA irradiation, UVC irradiation has the potential to induce more hydrophilicity on SLA-coated implants.

Impaired osteoblastic behavior and function on saliva-contaminated titanium and its restoration by UV treatment

The objective of this study was to examine behavior and function of osteoblasts on saliva-contaminated titanium and its potential improvement after UV light treatment. Acid-etched titanium disks were contaminated with human saliva. Osteoblasts derived from rat femur were cultured on contaminated and clean titanium disks. Contaminated disks further treated with UV light were also tested. The number of attached cells, the degree of cell spreading, and the expression of adhesion protein were significantly decreased on saliva-contaminated surfaces compared with clean surfaces. The gene expression of osteocalcin was also downregulated on contaminated surfaces, whereas ALP activity and mineralization were not significantly influenced. The impaired functions on contaminated surfaces were significantly increased if the surfaces were further treated with UV and even outperformed the ones on clean titanium surfaces. XPS analysis revealed that the atomic percentage of carbon and nitrogen detected on contaminated surfaces were substantially decreased after UV treatment. These results suggest that osteoblastic behavior and function were compromised on titanium surfaces contaminated with saliva. The compromised functions no longer happened if the surfaces were further treated with UV light, providing the basis to understand the effect of biological contamination on osseointegration and to explore UV treatment as a decontaminating technology.

Preparation of recombinant human-like collagen/fibroin scaffold and its promoting effect on vascular cells biocompatibility

A novel recombinant human-like collagen/fibroin scaffold has been prepared previously, which has high porosity, controllable pore size, and much better mechanical properties than the reported fibroin-based scaffold. In this research, the cell responses of vascular smooth muscle cells to this blend scaffold were examined in vitro. Cell morphology, adherence, and growth in scaffolds were observed by scanning electron microscopy, laser scanning confocal microscopy after staining of the cells with propidium iodide at 1, 3, 5, and 7 days, respectively. A wide range of measurements, including 3-[4,5–dimethylthiazol-2-yl]-2, 5-diphenyl tetrasodium bromide assay, and total intracellular protein content at the end of 7 days culture, were conducted. An increase of viability and protein content of vascular smooth muscle cells cultured in recombinant human-like collagen/fibroin scaffold was found. The laser scanning confocal microscopy and scanning electron microscopy results confirm that the cells readily adhered and proliferation in the blend than in fibroin scaffold, and indicate a better adhesion process. The positive effects were especially significant for vascular smooth muscle cells. The recombinant human-like collagen/fibroin scaffold could be a promising biomaterial for vascular tissue engineering.

Amino acid adsorption on anatase (101) surface at vacuum and aqueous solution: a density functional study

The adsorption of 20 amino acids (AAs) on the (101) surface of anatase titanium dioxide (TiO₂) has been investigated under the scheme of density functional theory. Through the analysis of adsorption geometries, amino group and side chains of AAs have been identified as the major side to adsorb on TiO₂, while the carboxyl group prefers to stay outside to avoid the repulsion between negatively charged oxygen from TiO₂ and AAs. On the surface, two-coordinated oxygen is the major site to stabilize AAs through O-H interactions. The above conclusion does not change when it is in the aqueous solution based on the calculations with AAs surrounded by explicit water molecules. The above knowledge is helpful in predicting how AAs and even peptides adsorb on inorganic materials. Graphical abstract The adsorption of 20 amino acids (AAs) on the (101) surface of anatase titanium dioxide (TiO₂) has been investigated under the scheme of density functional theory.

Atomic layer deposition of nano-TiO2 thin films with enhanced biocompatibility and antimicrobial activity for orthopedic implants

Titanium (Ti) and its alloys have been extensively used as implant materials in orthopedic applications. Nevertheless, implants may fail due to a lack of osseointegration and/or infection. The aim of this in vitro study was to endow an implant surface with favorable biological properties by the dual modification of surface chemistry and nanostructured topography. The application of a nanostructured titanium dioxide (TiO2) coating on Ti-based implants has been proposed as a potential way to enhance tissue-implant interactions while inhibiting bacterial colonization simultaneously due to its chemical stability, biocompatibility, and antimicrobial properties. In this paper, temperature-controlled atomic layer deposition (ALD) was introduced for the first time to provide unique nanostructured TiO2 coatings on Ti substrates. The effect of nano-TiO2 coatings with different morphology and structure on human osteoblast and fibroblast functions and bacterial activities was investigated. In vitro results indicated that the TiO2 coating stimulated osteoblast adhesion and proliferation while suppressing fibroblast adhesion and proliferation compared to uncoated materials. In addition, the introduction of nano-TiO2 coatings was shown to inhibit gram-positive bacteria (Staphylococcus aureus), gram-negative bacteria (Escherichia coli), and antibiotic-resistant bacteria (methicillin-resistant Staphylococcus aureus), all without resorting to the use of antibiotics. Our results suggest that the increase in nanoscale roughness and greater surface hydrophilicity (surface energy) together could contribute to increased protein adsorption selectively, which may affect the cellular and bacterial activities. It was found that ALD-grown TiO2-coated samples with a moderate surface energy at 38.79 mJ/m2 showed relatively promising antibacterial properties and desirable cellular functions. The ALD technique provides a novel and effective strategy to produce TiO2 coatings with delicate control of surface nanotopography and surface energy to enhance the interfacial biocompatibility and mitigate bacterial infection, and could potentially be used for improving numerous orthopedic implants.

Effect of different implant abutment surfaces on OBA-09 epithelial cell adhesion

For the long-term success of implants, it is necessary to achieve a direct contact between the implant and the subjacent bone. To avoid bacterial penetration that could adversely affect the initial wound healing as well as the long-term behavior of the implants, an early tissue barrier must form that is able to protect the biological peri-implant structures. Given the need of an effective tissue early barrier around dental implants, the present study evaluated, in vitro, the influence of physical and chemical characteristics of two implant abutment surfaces on gingival epithelial cells (OBA-9) adhesion. To this end, titanium (Ti) and zirconia (ZrO₂ ) disk-shaped specimens were used mimicking the abutment components surfaces, while bovine enamel (BE) and glass cover slips (GCS) disks served as positive and negative controls, respectively. Roughness and surface free energy (SFE) of all materials were evaluated previously to cellular adhesion step. In sequence, the effect of each material on cells morphology and viability was analyzed after 1 and 24 hr. The results showed that roughness and SFE had no effect on the cell viability data or on their interaction (p = .559), independent of a post-contact analysis of 1 or 24 hr. However, cells attachment and spreading increased after 24 hr on Ti and ZrO₂ than BE, corresponding to the highest SFE values. SFE appears to be an important property interfering on the quality of the soft tissue surrounding dental implants. These data can be considered a trigger point for developing new material surfaces.

Effect of Ultraviolet Irradiation on the Osseointegration of a Titanium Alloy with Bone

Introduction:

Attempt has been made to analyze the potential of titanium (Ti) alloy for osteointegration by the effect of surface photo functionalization in different aspects as follows: in Ringer's solution, in vitro cell growth, and in vivo study on rabbit. The present study was aimed to investigate the influence of ultraviolet (UV) light on surface topography, corrosion behavior, and bioactivity of indigenously manufactured samples of Ti alloy mini-implant.

Materials and Methods:

The study includes surface modification of Ti samples by UV treatment, corrosion testing of the specimens using Potentiostat (GAMRY System), qualitative examination of modified surface topography using scanning electron microscope, and cellular viability test on Ti alloy surface (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide ASSAY). To find the effect of UV light on implant bone integration, biochemical test was performed on the femur of rabbits.

Results and Discussion:

Corrosion resistance of untreated Ti alloy in Ringer's solution was found to be less, whereas corrosion rate was more. Corrosion resistance of UV-treated samples was found to increase significantly, thereby lowering the corrosion rate. Cell growth in UV-treated specimen was observed to be higher than that in untreated samples. It is important to mention that cell growth was significantly enhanced on samples which were UV treated for longer duration of time.

Conclusions:

There was a marked improvement in cell growth on UV-treated Ti alloy samples. Hence, it is expected that it would enhance the process of osseointegration of Ti with bone. Another important finding obtained was that the removal torque values of UV-treated implants were higher than that of untreated implants. The overall result reveals that UV treatment of implants does help us in speeding up the osseointegration process.

Modification of a SLA titanium surface with calcium-containing nanosheets and its effects on osteoblast behavior

The aim of this study was to present a procedure to prepare a calcium-containing nanosheets-modified sandblasted and acid etched (SLA) titanium surface and explore its effects on osteoblast behavior.

Novel antioxidant capability of titanium induced by UV light treatment

The intracellular production of reactive oxygen species (ROS) is a representative form of cellular oxidative stress and plays an important role in triggering adverse cellular events, such as the inflammatory reaction and delayed or compromised differentiation. Osteoblastic reaction to titanium with particular focus on ROS production remains unknown. Ultraviolet (UV) light treatment improves the physicochemical properties of titanium, specifically the induction of super hydrophilicity and removal of hydrocarbon, and eventually enhances its osteoconductivity. We hypothesized that there is a favorable regulatory change of ROS production within osteoblasts in contact with UV-treated titanium. Osteoblasts were cultured on titanium disks with or without UV-pretreatment. The intracellular production of ROS was higher on acid-etch-created rough titanium surfaces than on machine-prepared smooth ones. The ROS production was reduced by 40-50% by UV pretreatment of titanium regardless of the surface roughness. Oxidative DNA damage, as detected by 8-OHdG expression, was alleviated by 50% on UV-treated titanium surfaces. The expression of inflammatory cytokines was consistently lower in osteoblasts cultured on UV-treated titanium. ROS scavenger, glutathione, remained more without being depleted in osteoblasts on UV-treated titanium. Bio-burden test further showed that culturing osteoblasts on UV-treated titanium can significantly reduce the ROS production even with the presence of hydrogen peroxide, an oxidative stress inducer. These data suggest that the intracellular production of ROS and relevant inflammatory reaction, which unavoidably occurs in osteoblasts in contact with titanium, can be significantly reduced by UV pretreatment of titanium, implying a novel antioxidant capability of the particular titanium.

Plasma of Argon Affects the Earliest Biological Response of Different Implant Surfaces: An In Vitro Comparative Study

The aim of this in vitro study was to evaluate the early cell response and protein adsorption elicited by the argon plasma treatment of different commercially available titanium surfaces via a chair-side device. Sterile disks made of grade 4 titanium (n= 450, 4-mm diameter) with 3 surface topographies (machined, plasma sprayed, and zirconia blasted and acid etched) were allocated to receive 4 testing treatments (2% and 10% protein adsorption and cell adhesion with MC3T3-E1 and MG-63). Furthermore, the specimens were divided to undergo 1) argon plasma treatment (10 W, 1 bar for 12 min) in a plasma reactor, 2) ultraviolet (UV) light treatment for 2 h (positive control group), or 3) no treatment (control group). Pretreatment surface analyses based on a scanning electron microscope and profilometer images were also performed. Profilometric analysis demonstrated that the evaluated specimens perfectly suit the standard parameters. The use of argon plasma was capable of affecting the quantity of proteins adsorbed on the different surfaces, notwithstanding their roughness or topographic features at a low fetal bovine serum concentration (2%). UV light treatment for 2 h attained similar results. Moreover, both the plasma of argon and the UV light demonstrated a significant increase in the number of osteoblasts adherent at 10 min in all tested surfaces. Within its limitations, this in vitro study highlights the potential biological benefits of treating implant surfaces with plasma of argon or UV, irrespective of the roughness of the titanium surface. However, in vivo experiments are needed to confirm these preliminary data and settle the rationale of a treatment that might be clinically relevant in case of bone-reparative deficiencies.

Photofunctionalization enhances bone-implant contact, dynamics of interfacial osteogenesis, marginal bone seal, and removal torque value of implants: a dog jawbone study

OBJECTIVE

Ultraviolet (UV) light treatment of titanium, ie, photofunctionalization, has been extensively reported to enhance the osteoconductivity of titanium in animal and in vitro studies. This is the first study to examine whether photofunctionalization is effective on commercial dental implants in vivo.

MATERIALS AND METHODS

Dental implants with a microroughened surface were placed into dog jawbones. Photofunctionalization was performed by treating implants with UV light for 15 minutes using a photo device immediately before placement. Four weeks after placement, bone-implant integration was evaluated using a removable torque test and static and dynamic histology.

RESULTS

Implant surfaces were converted from hydrophobic to super-hydrophilic after photofunctionalization. Removable torque for photofunctionalized implants was significantly higher by 50% than that for untreated implants. Bone-implant contact (BIC) was significantly higher for photofunctionalized implants in all zones examined: marginal, cortical, and bone marrow zones. An intensive mineralized layer was exclusively present in marginal bone at photofunctionalized interface. Dynamic histology identified early-onset, long-lasting robust bone deposition at photofunctionalized interface.

CONCLUSIONS

Photofunctionalization enhanced the morphology, quality, and behavior of periimplant osteogenesis, including the increased BIC, expedited robust interfacial bone deposition, and improved marginal bone seal and support.

Implant stability change and osseointegration speed of immediately loaded photofunctionalized implants

OBJECTIVES

This study evaluated the degree and rate of implant stability development for photofunctionalized dental implants in humans.

MATERIALS AND METHODS

Thirty-three implants (7 patients) placed in the maxilla and immediate loaded were evaluated. Photofunctionalization was performed by treating implants with ultraviolet for 15 minutes immediately before placement. Implant stability was assessed by measuring the implant stability quotient (ISQ) weekly starting from implant placement up to 3 months. Osseointegration speed index (OSI), defined as ISQ increase per month, was also evaluated.

RESULTS

The average ISQ for photofunctionalized implants at week 6 was 78.0, which was considerably higher than the average ISQ of 66.1, reported in literature for various as-received implants after a longer healing time of 2 to 6 months. No stability dip was observed for photofunctionalized implants regardless of the initial ISQ values. The OSI for photofunctionalized implants was 6.3 and 3.1 when their initial ISQ was 65 to 70 and 71 to 75, respectively, whereas the OSI values for as-received implants calculated from literature ranged from -3.0 to 1.17 with an average of -0.10.

CONCLUSIONS

Photofunctionalization accelerated and enhanced osseointegration of dental implants, providing novel and practical avenues for further advancement in implant therapy.

Modulation of protein behavior through light responses of TiO2 nanodots films

In this work, the behavior of protein molecules adsorbed on TiO₂ nanodots films are modulated through the light responses of the nanodots. TiO₂ nanodots films are first prepared through phase separation induced self assembly. Then, bovine serum albumin (BSA) is adsorbed on TiO₂ nanodots films and exposed to ultraviolet (365 nm) illumination. It is found the conformation of surface-bound BSA molecules changes with ultraviolet illumination. Moreover, the BSA molecules conjugate to the surface-bound molecules, which are in the overlayer, are released. The reason is ascribed to that TiO₂ nanodots absorb ultraviolet and result in the increase of surface hydroxyl groups on nanodots. Such increase further leads to intensified attraction of -NH3 groups in the surface-bound BSA molecules. That not only changes the conformation of the surface-bound BSA molecules, but also weaken the conjugation between surface-bound molecules and other BSA molecules in the overlayer. Eventually, the overlayer of BSA molecules is released. It is believed that such protein conformation variation and release behavior induced through light responses of TiO₂ nanodots are crucial in understanding the biomedical performance of TiO₂ nanostructures. Also, it could be widely utilized in tailoring of the materials-protein interactions.

Effect of UV-photofunctionalization on oral bacterial attachment and biofilm formation to titanium implant material

Bacterial biofilm infections remain prevalent reasons for implant failure. Dental implant placement occurs in the oral environment, which harbors a plethora of biofilm-forming bacteria. Due to its trans-mucosal placement, part of the implant structure is exposed to oral cavity and there is no effective measure to prevent bacterial attachment to implant materials. Here, we demonstrated that UV treatment of titanium immediately prior to use (photofunctionalization) affects the ability of human polymicrobial oral biofilm communities to colonize in the presence of salivary and blood components. UV-treatment of machined titanium transformed the surface from hydrophobic to superhydrophilic. UV-treated surfaces exhibited a significant reduction in bacterial attachment as well as subsequent biofilm formation compared to untreated ones, even though overall bacterial viability was not affected. The function of reducing bacterial colonization was maintained on UV-treated titanium that had been stored in a liquid environment before use. Denaturing gradient gel-electrophoresis (DGGE) and DNA sequencing analyses revealed that while bacterial community profiles appeared different between UV-treated and untreated titanium in the initial attachment phase, this difference vanished as biofilm formation progressed. Our findings confirm that UV-photofunctionalization of titanium has a strong potential to improve outcome of implant placement by creating and maintaining antimicrobial surfaces.