Binding of plasma proteins to titanium dioxide nanotubes with different diameters

Insight into antibacterial effect of titanium nanotubular surfaces with focus on Staphylococcus aureus and Pseudomonas aeruginosa

Materials used for orthopedic implants should not only have physical properties close to those of bones, durability and biocompatibility, but should also exhibit a sufficient degree of antibacterial functionality. Due to its excellent properties, titanium is still a widely used material for production of orthopedic implants, but the unmodified material exhibits poor antibacterial activity. In this work, the physicochemical characteristics, such as chemical composition, crystallinity, wettability, roughness, and release of Ti ions of the titanium surface modified with nanotubular layers were analyzed and its antibacterial activity against two biofilm-forming bacterial strains responsible for prosthetic joint infection (Staphylococcus aureus and Pseudomonas aeruginosa) was investigated. Electrochemical anodization (anodic oxidation) was used to prepare two types of nanotubular arrays with nanotubes differing in dimensions (with diameters of 73 and 118 nm and lengths of 572 and 343 nm, respectively). These two surface types showed similar chemistry, crystallinity, and surface energy. The surface with smaller nanotube diameter (TNT-73) but larger values of roughness parameters was more effective against S. aureus. For P. aeruginosa the sample with a larger nanotube diameter (TNT-118) had better antibacterial effect with proven cell lysis. Antibacterial properties of titanium nanotubular surfaces with potential in implantology, which in our previous work demonstrated a positive effect on the behavior of human gingival fibroblasts, were investigated in terms of surface parameters. The interplay between nanotube diameter and roughness appeared critical for the bacterial fate on nanotubular surfaces. The relationship of nanotube diameter, values of roughness parameters, and other surface properties to bacterial behavior is discussed in detail. The study is believed to shed more light on how nanotubular surface parameters and their interplay affect antibacterial activity.

Multifunctional and bioinspired titanium surface with multilayer nanofilms for novel dental implant applications

Introduction: Smart multifunctional surfaces targeting intricate biological events or versatile therapeutic strategies are imminent to achieve long-term transmucosal implant success. Methods: This study used dopamine (DA), graphene oxide (GO), and type IV collagen (COL-IV) to construct multilayer nanofilms (DGCn) based on their universal adhesive and biomimetic properties to design a versatile and bioactive titanium implant. The characterization of DGCn on different titanium surfaces was performed, and its loading capacity, release profile, in situ gene delivery, and in vitro biological properties were preliminarily evaluated. Results: Our results demonstrate that hydrogenated TiO2 nanotubes (H) provide a better platform for the DGCn coating than machined Ti and air-TiO2 nanotubes. The H-DGC10 displayed the most stable surface with excellent loading capacity, sustained-release profile, and in situ gene transfection efficiency; this could be due to the high specific surface area of H and GO, as well as the functional groups in H, DA, and GO. Moreover, the H-DGC10 exhibited good biocompatibility for human oral epithelial cells and promoted the expression of integrin β4 and laminin 332, both being hemidesmosome-related proteins. Discussion: Our findings suggest that H-DGCn can be designed as a smart multifunctional interface for titanium implants to achieve long-term transmucosal implant success and aid in versatile therapeutic strategies.

Fine-Tuning the Nanostructured Titanium Oxide Surface for Selective Biological Response

Cardiovascular diseases are a pre-eminent global cause of mortality in the modern world. Typically, surgical intervention with implantable medical devices such as cardiovascular stents is deployed to reinstate unobstructed blood flow. Unfortunately, existing stent materials frequently induce restenosis and thrombosis, necessitating the development of superior biomaterials. These biomaterials should inhibit platelet adhesion (mitigating stent-induced thrombosis) and smooth muscle cell proliferation (minimizing restenosis) while enhancing endothelial cell proliferation at the same time. To optimize the surface properties of Ti6Al4V medical implants, we investigated two surface treatment procedures: gaseous plasma treatment and hydrothermal treatment. We analyzed these modified surfaces through scanning electron microscopy (SEM), water contact angle analysis (WCA), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) analysis. Additionally, we assessed in vitro biological responses, including platelet adhesion and activation, as well as endothelial and smooth muscle cell proliferation. Herein, we report the influence of pre/post oxygen plasma treatment on titanium oxide layer formation via a hydrothermal technique. Our results indicate that alterations in the titanium oxide layer and surface nanotopography significantly influence cell interactions. This work offers promising insights into designing multifunctional biomaterial surfaces that selectively promote specific cell types' proliferation─which is a crucial advancement in next-generation vascular implants.

Fabrication of Antibacterial TiO2 Nanostructured Surfaces Using the Hydrothermal Method

Implant-associated infections (IAI) are a common cause for implant failure, increased medical costs, and critical for patient healthcare. Infections are a result of bacterial colonization, which leads to biofilm formation on the implant surface. Nanostructured surfaces have been shown to have the potential to inhibit bacterial adhesion mainly due to antibacterial efficacy of their unique surface nanotopography. The change in topography affects the physicochemical properties of their surface such as surface chemistry, morphology, wettability, surface charge, and even electric field which influences the biological response. In this study, a conventional and cost-effective hydrothermal method was used to fabricate nanoscale protrusions of various dimensions on the surface of Ti, Ti₆Al₄V, and NiTi materials, commonly used in biomedical applications. The morphology, surface chemistry, and wettability were analyzed using scanning electron microscopy (SEM), X-ray photoemission spectroscopy (XPS), and water contact angle analysis. The antibacterial efficacy of the synthesized nanostructures was analyzed by the use of Escherichia coli bacterial strain. XPS analysis revealed that the concentration of oxygen and titanium increased on Ti and Ti₆Al₄V, which indicates that TiO₂ is formed on the surface. The concentration of oxygen and titanium however decreased on the NiTi surface after hydrothermal treatment, and also a small amount of Ni was detected. SEM analysis showed that by hydrothermal treatment alterations in the surface topography of the TiO₂ layer could be achieved. The oxide layer on the NiTi prepared by the hydrothermal method contains a low amount of Ni (2.8 atom %), which is especially important for implantable materials. The results revealed that nanostructured surfaces significantly reduced bacterial adhesion on the Ti, Ti₆Al₄V, and NiTi surface compared to the untreated surfaces used as a control. Furthermore, two sterilization techniques were also studied to evaluate the stability of the nanostructure and its influence on the antibacterial activity. Sterilization with UV light seems to more efficiently inhibit bacterial growth on the hydrothermally modified Ti₆Al₄V surface, which was further reduced for hydrothermally treated Ti and NiTi. The developed nanostructured surfaces of Ti and its alloys can pave a way for the fabrication of antibacterial surfaces that reduce the likelihood of IAI.

Effect of Silicon Carbide Coating on Osteoblast Mineralization of Anodized Titanium Surfaces

The objective of this study was to evaluate the influence of the titanium nanotube diameter and the effect of silicon carbide (SiC) coating on the proliferation and mineralization of pre-osteoblasts on titanium nanostructured surfaces. Anodized titanium sheets with nanotube diameters of 50 and 100 nm were used. The following four groups were tested in the study: (1) non-coated 50 nm nanotubes; (2) SiC-coated 50 nm titanium nanotubes; (3) non-coated 100 nm nanotubes and (4) SiC-coated 100 nm nanotubes. The biocompatibility and cytotoxicity of pre-osteoblasts were evaluated using a CellTiter-BlueCell Viability assay after 1, 2, and 3 days. After 3 days, cells attached to the surface were observed by SEM. Pre-osteoblast mineralization was determined using Alizarin-Red staining solution after 21 days of cultivation. Data were analyzed by a Kruskal−Wallis test at a p-value of 0.05. The results evidenced biocompatibility and non-cytotoxicity of both 50 and 100 nm diameter coated and non-coated surfaces after 1, 2 and 3 days. The statistical analysis indicates a statistically significant higher cell growth at 3 days (p < 0.05). SEM images after 3 days demonstrated flattened-shaped cells without any noticeable difference in the phenotypes between different diameters or surface treatments. After 21 days of induced osteogenic differentiation, the statistical analysis indicates significantly higher osteoblast calcification on coated groups of both diameters when compared with non-coated groups (p < 0.05). Based on these results, we can conclude that the titanium nanotube diameter did not play any role on cell viability or mineralization of pre-osteoblasts on SiC-coated or non-coated titanium nanotube sheets. The SiC coating demonstrated biocompatibility and non-cytotoxicity and contributed to an increase in osteoblast mineralization on titanium nanostructured surfaces when compared to non-coated groups.

Laminin Adsorption and Adhesion of Neurons and Glial Cells on Carbon Implanted Titania Nanotube Scaffolds for Neural Implant Applications

Interfacing neurons persistently to conductive matter constitutes one of the key challenges when designing brain-machine interfaces such as neuroelectrodes or retinal implants. Novel materials approaches that prevent occurrence of loss of long-term adhesion, rejection reactions, and glial scarring are highly desirable. Ion doped titania nanotube scaffolds are a promising material to fulfill all these requirements while revealing sufficient electrical conductivity, and are scrutinized in the present study regarding their neuron-material interface. Adsorption of laminin, an essential extracellular matrix protein of the brain, is comprehensively analyzed. The implantation-dependent decline in laminin adsorption is revealed by employing surface characteristics such as nanotube diameter, ζ-potential, and surface free energy. Moreover, the viability of U87-MG glial cells and SH-SY5Y neurons after one and four days are investigated, as well as the material's cytotoxicity. The higher conductivity related to carbon implantation does not affect the viability of neurons, although it impedes glial cell proliferation. This gives rise to novel titania nanotube based implant materials with long-term stability, and could reduce undesirable glial scarring.

Nanoporous Stainless Steel Materials for Body Implants-Review of Synthesizing Procedures

Despite the inadequate biocompatibility, medical-grade stainless steel materials have been used as body implants for decades. The desired biological response of surfaces to specific applications in the body is a highly challenging task, and usually not all the requirements of a biomaterial can be achieved. In recent years, nanostructured surfaces have shown intriguing results as cell selectivity can be achieved by specific surface nanofeatures. Nanoporous structures can be fabricated by anodic oxidation, which has been widely studied for titanium and its alloys, while no systematic studies are so far available for stainless steel (SS) materials. This paper reviews the current state of the art in the anodisation of SS; correlations between the parameters of anodic oxidation and the surface morphology are drawn. The results reported by various authors are scattered because of a variety of experimental configurations. A linear correlation between the pores' diameter anodisation voltage was deduced, while no correlation with other processing parameters was found obvious. The analyses of available data indicated a lack of systematic experiments, which are recommended to understand the kinetics of pore formation and develop techniques for optimal biocompatibility of stainless steel.

Influence of epigenetics on periodontitis and peri-implantitis pathogenesis

Periodontitis is a disease characterized by tooth-associated microbial biofilms that drive chronic inflammation and destruction of periodontal-supporting tissues. In some individuals, disease progression can lead to tooth loss. A similar condition can occur around dental implants in the form of peri-implantitis. The immune response to bacterial challenges is not only influenced by genetic factors, but also by environmental factors. Epigenetics involves the study of gene function independent of changes to the DNA sequence and its associated proteins, and represents a critical link between genetic and environmental factors. Epigenetic modifications have been shown to contribute to the progression of several diseases, including chronic inflammatory diseases like periodontitis and peri-implantitis. This review aims to present the latest findings on epigenetic influences on periodontitis and to discuss potential mechanisms that may influence peri-implantitis, given the paucity of information currently available.

Exosomal Composition, Biogenesis and Profiling Using Point-of-Care Diagnostics—Implications for Cardiovascular Disease

Arteriosclerosis is an important age-dependent disease that encompasses atherosclerosis, in-stent restenosis (ISR), pulmonary hypertension, autologous bypass grafting and transplant arteriosclerosis. Endothelial dysfunction and the proliferation of vascular smooth muscle cell (vSMC)-like cells is a critical event in the pathology of arteriosclerotic disease leading to intimal-medial thickening (IMT), lipid retention and vessel remodelling. An important aspect in guiding clinical decision-making is the detection of biomarkers of subclinical arteriosclerosis and early cardiovascular risk. Crucially, relevant biomarkers need to be good indicators of injury which change in their circulating concentrations or structure, signalling functional disturbances. Extracellular vesicles (EVs) are nanosized membraneous vesicles secreted by cells that contain numerous bioactive molecules and act as a means of intercellular communication between different cell populations to maintain tissue homeostasis, gene regulation in recipient cells and the adaptive response to stress. This review will focus on the emerging field of EV research in cardiovascular disease (CVD) and discuss how key EV signatures in liquid biopsies may act as early pathological indicators of adaptive lesion formation and arteriosclerotic disease progression. EV profiling has the potential to provide important clinical information to complement current cardiovascular diagnostic platforms that indicate or predict myocardial injury. Finally, the development of fitting devices to enable rapid and/or high-throughput exosomal analysis that require adapted processing procedures will be evaluated.

Bio-Performance of Hydrothermally and Plasma-Treated Titanium: The New Generation of Vascular Stents

The research presented herein follows an urgent global need for the development of novel surface engineering techniques that would allow the fabrication of next-generation cardiovascular stents, which would drastically reduce cardiovascular diseases (CVD). The combination of hydrothermal treatment (HT) and treatment with highly reactive oxygen plasma (P) allowed for the formation of an oxygen-rich nanostructured surface. The morphology, surface roughness, chemical composition and wettability of the newly prepared oxide layer on the Ti substrate were characterized by scanning electron microscopy (SEM) with energy-dispersive X-ray analysis (EDX), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and water contact angle (WCA) analysis. The alteration of surface characteristics influenced the material’s bio-performance; platelet aggregation and activation was reduced on surfaces treated by hydrothermal treatment, as well as after plasma treatment. Moreover, it was shown that surfaces treated by both treatment procedures (HT and P) promoted the adhesion and proliferation of vascular endothelial cells, while at the same time inhibiting the adhesion and proliferation of vascular smooth muscle cells. The combination of both techniques presents a novel approach for the fabrication of vascular implants, with superior characteristics.

Titanium dioxide nanotubes as drug carriers for infection control and osteogenesis of bone implants

Titanium implants have been widely used as one of the most effective treatments of bone defects. However, the lack of osteogenesis and bacteria-resistant activities result in high infection and loosening rates of titanium implants. Anodic oxidation could easily construct titanium dioxide nanotubes (TNTs) array on the surface of titanium, and the rough surface of TNTs is beneficial to the growth of osteoblast-related cells on the surface. And TNTs could be excellent drug carriers because of their single-entry tubular hollow structure. In this review, we aim at detailing the application of TNTs as drug carriers in the field of bone implants. Starting from the topography of TNTs, we illustrated the biological activity of the TNTs surface, the drugs for loading in TNTs, and the controlled and responsive release strategies of drug-loaded TNTs, respectively. At the end of this review, the shortcomings of TNTs as the drug carrier in the field of bone implants are discussed, and the development direction of this research field is also prospected.

Hemocompatibility of polyzwitterion-modified titanium dioxide nanotubes

Titanium dioxide nanotubes (TNTs) have attracted increasing interest as implantable materials due to their many desirable properties. However, their blood compatibility remains an issue. In this paper, TNTs of different diameters were modified with two types of zwitterionic polymers, poly(sulfobetaine methacrylate) (pSBMA) and poly(carboxybetaine methacrylate) (pCBMA), which were grafted onto the TNTs using ARGET-ATRP (activators regenerated by electron transfer atom transfer radical polymerization) method. Both pSBMA and pCBMA brushes coatings were found to greatly reduce adsorption of bovine serum albumin (BSA) and fibrinogen (Fib) onto the TNTs, showing excellent protein resistance. Moreover, the effects of the surface topography on the amount of protein adsorption were largely suppressed by the polyzwitterion coatings. The conformation of the protein adsorbed to the substrates was analyzed at the molecular level by Fourier-transform infrared reflection spectroscopy (FT-IR), which revealed that the BSA adsorbed on the polyzwitterion-modified TNTs adopted significantly different secondary structures from that on the virgin TNTs, whereas the conformation of the adsorbed Fib remained basically the same. The polyzwitterion-modified TNTs were found to be non-hemolytic, and platelet adhesion and activation was significantly reduced, showing excellent blood compatibility.

Use of Plasma Technologies for Antibacterial Surface Properties of Metals

Bacterial infections of medical devices present severe problems connected with long-term antibiotic treatment, implant failure, and high hospital costs. Therefore, there are enormous demands for innovative techniques which would improve the surface properties of implantable materials. Plasma technologies present one of the compelling ways to improve metal's antibacterial activity; plasma treatment can significantly alter metal surfaces' physicochemical properties, such as surface chemistry, roughness, wettability, surface charge, and crystallinity, which all play an important role in the biological response of medical materials. Herein, the most common plasma treatment techniques like plasma spraying, plasma immersion ion implantation, plasma vapor deposition, and plasma electrolytic oxidation as well as novel approaches based on gaseous plasma treatment of surfaces are gathered and presented. The latest results of different surface modification approaches and their influence on metals' antibacterial surface properties are presented and critically discussed. The mechanisms involved in bactericidal effects of plasma-treated surfaces are discussed and novel results of surface modification of metal materials by highly reactive oxygen plasma are presented.

Impedimetric Detection of Femtomolar Levels of Interleukin6, Interleukin 8, and Tumor Necrosis Factor Alpha Based on Thermally Modified Nanotubular Titanium Dioxide Arrays

An inexpensive, easy to prepare, and label-free electrochemical impedance spectroscopy-based biosensor has been developed for the selective detection of human interleukin 6 (IL-6), interleukin 8 (CXCL8, IL-8), and tumor necrosis factor (TNFα)-potential inflammatory cancer biomarkers. We describe a, so far, newly developed and unexplored method to immobilize antibodies onto a titanium dioxide nanotube (TNT) array by physical adsorption. Immobilization of anti-IL-6, anti-IL-8, and anti-TNFα on TNT and the detection of human IL-6, IL-8, and TNFα were examined using electrochemical impedance spectroscopy (EIS). The impedimetric immunosensor demonstrates good selectivity and high sensitivity against human biomarker analytes and can detect IL-6, IL-8, and TNFα at concentrations as low as 5 pg/mL, equivalent to the standard concentration of these proteins in human blood. The calibration curves evidenced that elaborated biosensors are sensitive to three cytokines within 5 ÷ 2500 pg/mL in the 0.01 M phosphate-buffered saline solution (pH 7.4).

Comparative investigations of in vitro and in vivo bioactivity of titanium vs. Ti-24Nb-4Zr-8Sn alloy before and after sandblasting and acid etching

To avoid the failure of clinical surgery due to "stress shielding" and the loosening of an implant, a new type of alloy, Ti-24Nb-4Zr-8Sn (TNZS), with a low Young's modulus acted as a new implant material in this work. Meanwhile, the surface characteristics, MC3T3-E1 cell behavior and in vivo osseointegration of the titanium and TNZS before and after sandblasting and acid etching were studied comparatively. TNZS and Ti had the same microstructure based on the transmission electron microscopy results. Meanwhile, the TNZS alloy had a lower Young's modulus and surface nanohardness compared with pure titanium. However, the corrosion resistance of Ti was better than that of the TNZS sample in simulated body fluid solution. In addition, the TNZS alloy after sandblasting and acid etching (SLATNZS) had excellent cell adhesion, proliferation, differentiation, ALP activity and in vivo osseointegration ability such as there being almost no soft tissue as compared with other implants. Based on the current results, the new type of Ti-24Nb-4Zr-8Sn alloy showed good potential and promising application prospects in its biochemical aspects.

Crystallized TiO2 Nanosurfaces in Biomedical Applications

Crystallization alters the characteristics of TiO2 nanosurfaces, which consequently influences their bio-performance. In various biomedical applications, the anatase or rutile crystal phase is preferred over amorphous TiO2. The most common crystallization technique is annealing in a conventional furnace. Methods such as hydrothermal or room temperature crystallization, as well as plasma electrolytic oxidation (PEO) and other plasma-induced crystallization techniques, present more feasible and rapid alternatives for crystal phase initiation or transition between anatase and rutile phases. With oxygen plasma treatment, it is possible to achieve an anatase or rutile crystal phase in a few seconds, depending on the plasma conditions. This review article aims to address different crystallization techniques on nanostructured TiO2 surfaces and the influence of crystal phase on biological response. The emphasis is given to electrochemically anodized nanotube arrays and their interaction with the biological environment. A short overview of the most commonly employed medical devices made of titanium and its alloys is presented and discussed.

TiO2 Nanotubes Alleviate Diabetes-Induced Osteogenetic Inhibition

Background

Patients with diabetes mellitus (DM) have a higher failure rate of dental implant treatments. However, whether titanium (Ti) implants with TiO₂ nanotubes (TNT) surface can retain their biocompatibility and osteogenetic ability under DM conditions has not been investigated; in addition, their behavior in DM conditions is not well characterized.

Materials and Methods

Pure Ti discs were surface treated into the polishing (mechanically polished, MP), sandblasted and acid-etched (SLA), and TNT groups. Scanning electron microscopy was used to examine the surface morphology. The cell adhesion and proliferation ability on different modified Ti surfaces at various glucose concentrations (5.5, 11, 16.5, and 22 mM) was detected by the CCK-8 assay. The osteogenetic ability on different modified Ti surfaces under high-glucose conditions was evaluated by alkaline phosphatase (ALP), osteopontin (OPN) immunofluorescence, Western blot, and Alizarin Red staining in vitro. Detection of cell apoptosis and intracellular reactive oxygen species (ROS) was undertaken both before and after N-acetylcysteine (NAC) treatment to assess the oxidative stress associated with different modified Ti surfaces under high-glucose conditions. An in vivo study was conducted in DM rats with different modified Ti femoral implants. The osteogenetic ability of different modified Ti implants in DM rats was assessed using a micro-CT scan.

Results

High-glucose conditions inhibited cell adhesion, proliferation, and osteogenetic ability of different modified Ti surfaces. High-glucose conditions induced higher apoptosis rate and intracellular ROS level on different modified Ti surfaces; these effects were alleviated by NAC. Compared with the SLA surface, the TNT surface alleviated the osteogenetic inhibition induced by high-glucose states by reversing the overproduction of ROS in vitro. In the in vivo experiment, micro-CT scan analysis further confirmed the best osteogenetic ability of TNT surface in rats with DM.

Conclusion

TNT surface modification alleviates osteogenetic inhibition induced by DM. It may provide a more favorable Ti implant surface for patients with DM.

Bioactive surface-modified Ti with titania nanotube arrays to design endoprosthesis for maxillofacial surgery: structural formation, morphology, physical properties and osseointegration

Modification of the surface of titanium into titania (TiO₂) nanotube (TNT) arrays was performed by electrochemical anodization to design an endoprosthesis for maxillofacial surgery. TNT arrays with different surface structures were successfully coated on titanium substrates by varying the anodizing voltages and annealed at 450 °C for 4 h. The phase composition and morphology of the nanotubes were examined by x-ray powder diffraction and field-emission scanning electron microscopy, respectively. The biological functions and water wettability of various surface structures were also investigated. The results demonstrated that the annealed nanotubes were composed of an anatase phase only at all applied voltages. The tube diameters and lengths increased as the voltage increased. The surfaces with modification had more wettability, cell adhesion, proliferation, alkaline phosphatase activity and calcium deposition than the surfaces without modification. Finally, the results demonstrated that a modified surface of titanium to produce TNT arrays as a biomaterial is promising to design an osseointegrated surface of endoprosthesis for maxillofacial surgery.

Titanium Dioxide Nanotube Arrays for Cardiovascular Stent Applications

Efficient stent implantation among others depends on avoiding the aggregation of platelets in the blood vessels and appropriate proliferation of endothelial cells and controlled proliferation of smooth muscle cells, which reduces the development of pathology, such as neointimal hyperplasia, thrombosis, and restenosis. The current article provides an elegant solution for prevention of platelet and smooth muscle cell adhesion and activation on stent surfaces while obtaining surface conditions to support the growth of human coronary artery endothelial cells. This was achieved by surface nanostructuring and chemical activation of the surface. Specific nanotopographies of titanium were obtained by electrochemical anodization, while appropriate chemical properties were attained by treatment of titanium oxide nanotubes by highly reactive oxygen plasma. Surface properties were studied by scanning electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. Wettability was evaluated by measuring the water contact angle. The influence of nanostructured morphology and plasma modification on in vitro biological response with human coronary artery endothelia and smooth muscle cells as well as whole blood was studied. Our results show that a combination of nanostructuring and plasma modification of the surfaces is an effective way to achieve desired biological responses necessary for implantable materials such as stents.

Plasma Proteins at the Interface of Dental Implants Modulate Osteoblasts Focal Adhesions Expression and Cytoskeleton Organization

The host-material interface is a crucial relationship dictating the possibility of successful osseointegration in implant dentistry. The aim of the present study was to characterize the effects of plasma proteins pre-adsorption on the adhesion capacity of osteoblasts, which occurs immediately after implant insertion in vivo. After having pre-adsorbed human plasma proteins on a machined and microrough titanium surface, MC3T3-E1 osteoblasts adhesion was evaluated through crystal violet cell adhesion assay, immunofluorescence staining for cytoskeleton, focal adhesions and cell nuclei, and scanning electron microscopy. The pre-adsorbed protein layer markedly affected the adhesion rate of cells, as well as their morphology and the expression of focal contacts. Moreover, protein adsorption to the underlying titanium surface was found to be correlated to surface pre-wetting. Thus, the early adsorption of serum proteins to the interface of dental implants impacts cell adhesion in terms of strength and of focal adhesions expression.

Photocatalytic Treatment of Paracetamol Using TiO2 Nanotubes: Effect of pH

Pharmaceuticals are considered among the group of emerging contaminants. Paracetamol is a moderate painkiller, which has been detected in ground and surface water. Photodegradation of paracetamol at a wavelength of radiation of 254 nm with TiO2 nanotubes was studied by UV-spectroscopy, HPLC and measurement of the potential zeta in dependence of the solution pH. The efficiency of the photodegradation of paracetamol (20 mg L−1) was 99% after 100 min exposure. Application of the Langmuir-Hinshelwood equation allowed the evaluation of the rate constant. Non-organic by-products were detected under the conditions of the chromatographic analysis. The photoreaction was faster at pH 6.5, a value at which adsorption was favored, leading to higher efficiency.

Plasma-Induced Crystallization of TiO₂ Nanotubes

Facile crystallization of titanium oxide (TiO₂) nanotubes (NTs), synthesized by electrochemical anodization, with low pressure non-thermal oxygen plasma is reported. The influence of plasma processing conditions on TiO₂ NTs crystal structure and morphology was examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). For the first time we report the transition of amorphous TiO₂ NTs to anatase and rutile crystal structures upon treatment with highly reactive oxygen plasma. This crystallization process has a strong advantage over the conventional heat treatments as it enables rapid crystallization of the surface. Thus the crystalline structure of NTs is obtained in a few seconds of treatment and it does not disrupt the NTs’ morphology. Such a crystallization approach is especially suitable for medical applications in which stable crystallized nanotubular morphology is desired. The last part of the study thus deals with in vitro biological response of whole blood to the TiO₂ NTs. The results indicate that application of such surfaces for blood connecting devices is prospective, as practically no platelet adhesion or activation on crystallized TiO₂ NTs surfaces was observed.

Effects of hydrogenated TiO2 nanotube arrays on protein adsorption and compatibility with osteoblast-like cells

Background

Modified titanium (Ti) substrates with titanium dioxide (TiO₂) nanotubes have broad usage as implant surface treatments and as drug delivery systems.

Methods

To improve drug-loading capacity and accelerate bone integration with titanium, in this study, we hydrogenated anodized titanium dioxide nanotubes (TNTs) by a thermal treatment. Three groups were examined, namely: hydrogenated TNTs (H₂-TNTs, test), unmodified TNTs (air-TNTs, control), and Ti substrates (Ti, control).

Results

Our results showed that oxygen vacancies were present in all the nanotubes. The quantity of -OH groups greatly increased after hydrogenation. Furthermore, the protein adsorption and loading capacity of the H₂-TNTs were considerably enhanced as compared with the properties of the air-TNTs (P<0.05). Additionally, time-of-flight secondary ion mass spectrometry (TOF-SIMS) was used to investigate the interactions of TNTs with proteins. During the protein-loading process, the H₂-TNTs not only enabled rapid protein adsorption, but also decreased the rate of protein elution compared with that of the air-TNTs. We found that the H₂-TNTs exhibited better biocompatibility than the air-TNT and Ti groups. Both cell adhesion activity and alkaline phosphatase activity were significantly improved toward MG-63 human osteoblast-like cells as compared with the control groups (P<0.05).

Conclusion

We conclude that hydrogenated TNTs could greatly improve the loading capacity of bioactive molecules and MG-63 cell proliferation.

When epigenetics meets bioengineering-A material characteristics and surface topography perspective

The field of tissue engineering and regenerative medicine (TE/RM) involves regeneration of tissues and organs using implantable biomaterials. The term epigenetics refers to changes in gene expression that are not encoded in the DNA sequence, leading to remodeling of the chromatin and activation or inactivation of gene expression. Recently, studies have demonstrated that these modifications are influenced not only by biological cues but also by mechanical and topographical signals. This review highlights the current knowledge on emerging approaches in TE/RM with a focus on the effect of materials and topography on the epigenetic expression pattern in cells with potential impacts on modulating regenerative biology. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2065-2071, 2018.

Electrokinetic Properties of TiO2 Nanotubular Surfaces

Surface charge is one of the most significant properties for the characterisation of a biomaterial, being a key parameter in the interaction of the body implant with the surrounding living tissues. The present study concerns the systematic assessment of the surface charge of electrochemically anodized TiO2 nanotubular surfaces, proposed as coating material for Ti body implants. Biologically relevant electrolytes (NaCl, PBS, cell medium) were chosen to simulate the physiological conditions. The measurements were accomplished as titration curves at low electrolytic concentration (10(-3) M) and as single points at fixed pH but at various electrolytic concentrations (up to 0.1 M). The results showed that all the surfaces were negatively charged at physiological pH. However, the zeta potential values were dependent on the electrolytic conditions (electrolyte ion concentration, multivalence of the electrolyte ions, etc.) and on the surface characteristics (nanotubes top diameter, average porosity, exposed surface area, wettability, affinity to specific ions, etc.). Accordingly, various explanations were proposed to support the different experimental data among the surfaces. Theoretical model of electric double layer which takes into account the asymmetric finite size of ions in electrolyte and orientational ordering of water dipoles was modified according to our specific system in order to interpret the experimental data. Experimental results were in agreement with the theoretical predictions. Overall, our results contribute to enrich the state-of-art on the characterisation of nanostructured implant surfaces at the bio-interface, especially in case of topographically porous and rough surfaces.

Biocompatibility of different nanostructured TiO2 scaffolds and their potential for urologic applications

Despite great efforts in tissue engineering of the ureter, urinary bladder, and urethra, further research is needed in order to improve the patient's quality of life and minimize the economic burden of different lower urinary tract disorders. The nanostructured titanium dioxide (TiO₂) scaffolds have a wide range of clinical applications and are already widely used in orthopedic or dental medicine. The current study was conducted to synthesize TiO₂ nanotubes by the anodization method and TiO₂ nanowires and nanospheres by the chemical vapor deposition method. These scaffolds were characterized with scanning electron microscopy (SEM) and X-ray diffraction (XRD) methods. In order to test the urologic applicability of generated TiO₂ scaffolds, we seeded the normal porcine urothelial (NPU) cells on TiO₂ nanotubes, TiO₂ nanowires, TiO₂ nanospheres, and on the standard porous membrane. The viability and growth of the cells were monitored everyday, and after 3 weeks of culturing, the analysis with scanning electron microscope (SEM) was performed. Our results showed that the NPU cells were attached on all scaffolds; they were viable and formed a multilayered epithelium, i.e., urothelium. The apical plasma membrane of the majority of superficial NPU cells, grown on all three different TiO₂ scaffolds and on the porous membrane, exhibited microvilli; thus, indicating that they were at a similar differentiation stage. The maximal caliper diameter measurements of superficial NPU cells revealed significant alterations, with the largest cells being observed on nanowires and the smallest ones on the porous membrane. Our findings indicate that different nanostructured TiO₂ scaffolds, especially nanowires, have a great potential for tissue engineering and should be further investigated for various urologic applications.