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Nowadays, there is a growing need for using functionally graded materials (FGM) for using in bio-medical application. This need is prominent especially for the effect of gradient structures and in implant applications. To optimize both mechanical and biocompatibilities properties or change bio reactivity in each region, powder metallurgy technique is used in this study to fabricate titanium/hydroxyapatite (Ti/HAP) and other FGM implants with the concentration changed gradually in the longitudinal direction of cylindrical shapes. Concentration gradient was formed by packing dry powders into mold or sedimentation in solvent liquid processes. For the sintering process, three spark plasma sintering (SPS), high-frequency induction heating and electric furnace heating techniques were used to sinter the materials. During the fabrication of Ti/HAP FGMs and due to the stress relaxation in the implanted regions of bones, Brinell hardness decreased gradually from Ti part to HAP part. The results showed that the tissue reaction occurred gradiently in response to the graded structure of the FGM, which implies the possibility of controlling the tissue response through the gradient function of the FGM.

The in vitro and in vivo biocompatibility of the ZnO nanoparticles were evaluated using cell model and animal model, by MTT assay, flow cell cytometry, pathological optical and electron microscopy examinations. Both the L929 cell and Hela cell proliferative activity were strongly inhibited by the presence of ZnO nanoparticles, no matter cultured with low dose and high dose suspension. AnnexinV-FITC/PI-FCM assay showed that the number of necrotic cell and apoptotic cell increased significantly. Feeding the ZnO nanoparticle suspension through digestive tract would lead to the damage to some primary organs (heart, lung, liver and kidney). Further investigation by TEM showed the expanded sarcoplasmic reticulum and organelle vacuolation features.

In order to avoid the "metallic smile" appearance of metal wires when undergoing orthodontic treatment, epoxy resin/polytetrafluorethylene coating TiNi arch wires were made by dipping method. TiO₂ and FeFe₂O₄ were chosen as dyes in order to match the color of teeth and the color schemes were fixed by spectrophotometer method. The biocompatibility of coating was also examined. The results showed that the cytotoxicity of the coating was grade I, and without mutagenesis and carcinogenesis. Skin sensitization assay showed no erythema or oedema response and epithelial was integrated according to mucous membrane irritation. Thus, good behavior in clinic can be anticipated.

Ag/TiO₂ coating was prepared by anodizing the surface of Ti followed by electrodeposition of silver. By X-ray diffraction (XRD) analyses, that indicated the crystalline size of Ag deposit onto the oxidized surface of Ti was around 32 nm. Scanning electron microscopy (SEM) images of the oxidized surface with and without Ag deposit show that TiO₂ is formed uniformly but Ag deposit consisted of numerous spherical structures. The Escherichia coli and Staphylococcus aureus bacteria were utilized to test the antibacterial effect of Ag/TiO₂ coating which showed more than 99% of bacteria were killed after 24 h incubation. The results of in vitro test showed Ag/TiO₂ coating is also biocompatible.

In the present study, two novel silicate glass-ceramics having chemical composition 38SiO₂–41CaO–6P₂O₅–($15-x$)Na₂O–$x$CaF₂ ($x=0$, 0.43 mol%) were synthesized. These glass derivatives were subjected to stimulated body fluid for 24 days in SBF under static condition at $37^{\circ }$C in order to evaluate the bioactive properties of specimens. The antibacterial activity of glass ceramics against three pathogenic bacteria was determined using the modified Kirby Bauer method. It was found that the antibacterial activity primarily depends on the dissolution rate; faster release of ions caused rapid increase in the pH of the solution. Antibacterial properties were found to be strongly affected by changes in the pH of supernatant. The in vitro bioactivity assays showed that both glass derivatives were capable of bonding with bone and secondly effectively inhibit bacteria. However, the glass ceramic without CaF₂ (B2) showed high dissolution rate, better bioactive ability and stronger antibacterial efficacy.

In this study, we compared the bio-corrosion resistance and biocompatibility of a ZrTi-based BMGMC (Zr_58.5Ti_14.3Ni_4.9Cu_6.1Nb_5.2Be_11.0). The Ti-6Al-4V alloy was used as a reference material. By utilizing the electrochemical measurements and M3T3 cell culture, the corrosion resistance and biocompatibility of this BMGMC were evaluated. The BMGMC displayed high positive corrosion potentials and low corrosion current densities, which indicated that this material exhibited a highly improved corrosion resistance than the Ti alloy. The cells could adhere on the surface of this BMGMC and exhibited improved cellular behaviors, such as cellular viability and cytoskeketal structure. In summary, the ZrTi-based BMGMC showed great potential for applications in the hard tissue implants.

In this study, properties such as hydrophilicity and biocompatibility of surfaces prepared with 2-methacryloyloxyethyl phosphorylcholine (MPC) were evaluated under neutral to acidic conditions. The MPC-modified surface exhibit high hydrophilicity in neutral condition due to the ionization effect, while under acidic conditions below pH 3, the hydrophilicity gradually decreased due to the decrease in the negative charge of the PC groups. Biocompatibility property was evaluated by measuring the adsorption prevention effect against fibrinogen. The adsorption of fibrinogen was hardly observed on scanning electronic microscope (SEM) pictures under pH 7.6, which was significantly lower than that of the bare glass. However, the adsorption ratio increased under acidic conditions of pH 2.8 indicating a decrease in biocompatibility.

Membrane wetting by liquid absorbents limits the performance of membrane contactor, which shows the necessity of using superhydrophobic membranes in these systems. In recent years, the use of plasma irradiation to modify polymer membranes has received much attention from researchers. In this experimental research, the polypropylene membrane surface was irradiated with CF₄ plasma at different times to reduce the membrane wetting and create a superhydrophobic surface. The modified membranes were evaluated in terms of measurements of roughness and morphology, chemical properties, and hydrophilicity. In the results of the AFM^* and SEM^† tests, the structural difference caused by the surface modification and the resulting roughness can be well observed. The FTIR^‡ results showed the creation of new functional groups due to the surface modification process. The physicochemical changes of the modified surface led to an increase in the CA^§ to 166^∘. Finally, the performance of modified membranes was evaluated for protein adsorption, and the results indicated a significant decrease in adsorption for modified superhydrophobic membranes compared to the control membrane. Achieving superhydrophobic PP membranes by plasma treatment without damaging the physical structure of these membranes is a significant result that is simply not achieved by other methods because it causes the membrane tissue to disintegrate. It has also been shown that the conditions of plasma application play a decisive role in the hydrophobicity of modified surfaces.

In this paper, the applications and qualifications of biomedical materials are introduced. In regard to the hard tissue implants, the biocompatibility can be improved by preparing various bio-ceramic and bio-glass coatings. In view of this, the principles, characteristics, and applications of surface modification (plasma spraying, electrostatic spray deposition, micro-arc oxidation, pulsed laser deposition, sol–gel deposition, and magnetron sputtering) in biomedical materials are reviewed. In addition, the research direction of improving biocompatibility by surface modification is presented.

Biocompatibility is crucial for implants. In recent years, numerous researches were conducted aiming to modify titanium alloys, which are the most extensively used materials in orthopedic fields. The application of zirconia in the biomedical field has recently been explored. In this study, the biological ZrO₂ coating was synthesized on titaniumalloy (Ti6Al4V) substrates by a duplex-treatment technique combining magnetron sputtering with micro-arc oxidation (MAO) in order to further improve the corrosion resistance and biocompatibility of Ti6Al4V alloys. The microstructures and phase constituents of the coatings were characterized by scanning electron microscope (SEM) equipped with energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD), the surface wettability was evaluated by contact angle measurements. The results show that ZrO₂ coatings are porous with pore sizes less than 2$\mu$m and consist predominantly of the tetragonal ZrO₂ (t-ZrO${}_2)$ and cubic ZrO₂(c-ZrO${}_2)$ phase. Electrochemical tests indicate that the corrosion rate of Ti6Al4V substrates is appreciably reduced after surface treatment in the phosphate buffer saline (PBS). In addition, significantly improved cell adhesion and growth were observed from the ZrO₂/Zr surface. Therefore, the hybrid approach of magnetron sputtering and MAO provides a surface modification for Ti6Al4V to achieve acceptable corrosion resistance and biocompatibility.

Nanoparticles of alpha ferric oxide ($\alpha$-Fe₂O₃) were prepared by the hydrothermal method. Structural properties of $\alpha$-Fe₂O₃ were determined by XRD, SEM and AFM measurements. The particles had a good matching with standard pattern. Average particle size was about 90nm and the distribution extended from about 20nm to 120nm. Biocompatibility study of ferric oxide nanoparticles against bacteria, parasites, tumor cell line and normal cells was determined. No antibacterial activity was observed for the concentration, of ferric oxide nanoparticles in distilled water, up to 1.5mg/ml vs. E. coli and S. aureus. Moreover, MTT assay was used to determine the cytotoxicity against parasites and cells. Intermediate cytotoxicity (53.30%) of 1.5mg/ml of prepared nanoparticles was noted against L. tropica, while weak cytotoxicity of 5.20% was observed against L. donovani at the same concentration of ferric oxide nanoparticles. On the other hand, the prepared nanoparticles revealed low cytotoxicity (47.28%) against SR tumor cell line, while no cytotoxicity was shown against lymphocytes, as a model of normal cells.

This research work’s aim was to enhance the biocompatibility of the commercially pure titanium (cpTi-2) surface via Au-ion irradiation. Various ion dosages, i.e. $7.4\times 10^{11}$ (Au-11), $6.47\times 10^{12}$ (Au-12) and $5.53\times 10^{13}$ (Au-13) ions$\cdot$cm${}^{-2}$, were produced by exposing the polished cpTi-2 samples to Au-ion beam at room temperature. The surface topographic features of cpTi-2 and the effects of Au-ion-implanted surfaces were examined by atomic force microscopy and XRD analysis. Open-Circuit Potential (OCP), Potentiodynamic Polarization Scans (PPS) and Electrochemical Impedance Spectroscopy (EIS) were used to compare the electrochemical behavior of the cpTi-2 and Au-ion-implanted samples in Ringer’s lactate (RL) solution at 37^∘C. The effects of Au-ion irradiation on the proliferation of mesenchymal stem cells (MSCs) were estimated during 24h and 48h of exposure. Based on the experimental results, Au-12 samples presented more positive OCP and lower corrosion rate in RL solution than the Au-11 and Au-13 samples. No significant change in the morphology of the MSCs was observed after exposure to the Au-ion-implanted samples. Similar to the controlled medium, the percentage of viability of the cells of the cells on Au-12 increased from 75% to 165% on the surface of Au-13 samples during 48h of incubation indicating the positive effects of Au-ion irradiation for biocompatibility.

Using biomaterials to create new technologies like sensors, electrodes, prosthetics, bioelectrodes, skin substitutes, and drug delivery systems is known as biotechnology. It is crucial for medical procedures like surgery, dentistry, prosthetics, biosensors, electrophoresis, bioelectricity, implantation, and many other fields of human endeavor. Mesoporous bioactive glasses (MBGs) are the main bioactive materials used for bone regeneration due to their large surface area and high pore content, which can increase bioactivity and facilitate new bone formation. Their large surface area and high pore volume result in higher surface chemical reactivity as compared to nonmesoporous bioactive glasses, hence they have a higher chemical reactivity. Cells were aligned on the surface of an implant in some other investigation when topographical characteristics were produced by electro-hydrodynamic printing with hydroxyapatite, and permanent small silica spheres are commonly used in biomedical applications for cell labeling or medication administration. Because of the inclusion of porosities in MBG matrixes, as well as their large surface area, the deposition of hydroxyl carbonate apatite is considerably accelerated. MBGs can be cultured in the laboratory with a variety of methods, depending on how they will be employed in medical therapy. Melt-quenching therapy, spray pyrolysis method, sol-gel manufacturing technique, spray drying process, and modified Stber method are some of these tactics. To guarantee that MBGs are appropriate for use in medical care, several characterization procedures like SEM, TEM, BET, XRD, etc. should be used in the laboratory.

As implant materials, titanium and its alloys have been extensively utilized because of their exceptional mechanical properties and biocompatibility. Despite this, corporations and researchers alike have kept up their aggressive pursuit of better alloys since there are still issues that require immediate attention. One of these causes a problem with stress shielding as a noticeable variation in the elastic modulus of the implant material. Ti alloys release harmful ions after extended usage. The poor bioactivity of the Ti alloy surface slows the healing process. In order to address these problems, additional research has concentrated on developing Ti alloys for the 21st century that contain a more suitable phase and change the surface of the alloy from inherently bioinert to bioactive. This study assesses the knowledge presently existing on the biological, chemical, mechanical, and electrochemical characteristics of important $\beta$-Ti alloys created in recent years with the objective to provide scientific justification for using $\beta$-titanium-based alloys as a substitute for cpTi. Dental implants might be made using $\beta$-Ti alloys as an alternative. The enhanced alloy qualities, which include a lower modulus of elasticity, improved strength, suitable biocompatibility, and good abrasion and excellent resistance to corrosion, offer the essential proof. Additionally, structural, chemical, and thermomechanical modifications to $\beta$-Ti alloys allow for the production of materials that may be tailored to the needs of unique instances for clinical practises. By researching the paper, the performance and attributes of $\beta$-titanium alloy are compared to those of other forms of titanium alloy, such as $\alpha$ titanium alloys. To support their usage as cpTi substitutes, in vivo studies are required to assess new $\beta$-titanium alloys.

The degradation control of implants has now become a most critical factor for investigation. The rapid degradation or uncontrolled degradation of metals causes allergic reaction and implants failure. The biocompatibility and biodegradability of biometals are essential properties for the development of bioimplants. The biodegradation is the chemical reaction of implants metal with the surrounding body fluids. The gradual dilution of metal oxide with the body fluid is considered as a degradation. Magnesium, zinc, and iron metals are biodegradable metals. The biodegradability of as-cast metals is not capable of fulfilling the need of patients, therefore, degradation of implants is required to be in control. Many more research articles have been published on improvement of corrosion resistive implant surface by coating, passivation oxide layer, plasma spraying, electropolishing, blasting, chemical etching, laser treatment, heat treatment, severe plastic deformation (SPD), alloying, and development of surface composites. This paper critically reviewed the surface modification and surface composite fabrication techniques to improve the biodegradability, biocompatibility, and strength of implants.

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Recently, we introduced magnetophoretic circuits, composed of overlaid magnetic and metallic layers, as a novel single-cell analysis (SCA) tool. We showed the ability of these circuits in organizing large single-particle and particle-pair arrays. Assembling the cells in microarrays is performed with the ultimate goal of running temporal phenotypic analyses. However, for long-term studies, a suitable microenvironment for the cells to normally grow and differentiate is needed. Towards this goal, in this study, we run required biocompatibility tests, based on which we make the magnetophoretic-based microchip a suitable home for the cells to grow. The results confirm the ability of these chips in cell handling and show no unwanted cell behavior alteration due to the applied shear stress on them, the magnetic labeling, or the microenvironment. After this achievement, this tool would be ready for running important single-cell studies in oncology, virology, and medicine.

Biodegradable materials have various advantages compared to nonbiodegradable materials. Developing implants using biodegradable materials eliminates the need for secondary surgery, improves mechanical and biological properties, and improves biocompatibility. Magnesium (Mg) and its alloys are frequently used in orthopedic applications nowadays. However, the rapid degradation of Mg poses a substantial challenge. As a result, for the bone to heal properly, a proper balance between implant degeneration rate and bone healing must be obtained. Mg has certain other drawbacks, such as the need for an inert atmosphere when employing powder metallurgy and casting procedures to manufacture it because of its reactive nature. In this paper, Additive manufacturing (AM) techniques for manufacturing orthopedic biodegradable implants made of Mg and its alloys are discussed which helps in obtaining improved biological and mechanical properties of the implants. These orthopedic implants should have a controlled rate of degradation and antibacterial functional surfaces. There is also a description of the use of several AM processes utilized to enhance the mechanical and biological characteristics of implants employing Mg. This paper also seeks to present the concept of integrating established techniques into a production process to obtain the needed biodegradable implant material for orthopedic applications.

Quantum Dots (QDs) are recently emerging as the alternative to organic fluorescent probes in bio imaging applications. In the present study, CdTe QDs were prepared in aqueous phase using a stable tellurium source in presence of a capping agent capable of stabilizing and regulating its growth in the pH range of 6.0–8.0, such that it is amenable for use in biological systems. The spectroscopic and microstructural studies confirmed the formation of CdTe nanoparticles capped by mercaptosuccinic acid (MSA) of average size 2.5 nm with narrow size distribution. These MSA–CdTe QDs have shown tunable fluorescence with high quantum yield, broad absorption and symmetric fluorescence spectra. Of the different QDs emitting varied luminescence, the yellow, orange and red QDs were taken up for further characterization, to assess their potential in bioimaging applications. The cytotoxicity assays in mammalian lymphocytes showed that these QDs have a very high order cell viability and low level of toxicity when incubated with varying QD concentrations (20–130 nm).

Nanohydroxyapatite (nHAp) has gained considerable concerns due to its vast potential in biomedical applications such as drug delivery, tissue engineering and bone repair. However, the preparation of HAp nanostructures in a controllable manner under environment-friendly reaction conditions remains a challenge. In recent years, the use of biological macromolecules or proteins as templates in the production of nanomaterials has gained more attention due to the relatively mild physical conditions needed for biomimetic synthesis. In this study, a novel nHAp was fabricated by employing bovine serum albumin (BSA) as template under mild condition. After that, the as-obtained nanostructured materials which have well-defined structures and morphologies were characterized by various methods. Furthermore, the rod-like shaped hydroxyapatite demonstrated improved stability properties, as well as cell viability and biocompatibility, compared to BSA free synthesized c-HAp. We expect that this pleasantly novel research will render new insights into the fabrication strategies of nanomaterials and be of practical importance for the expanding biological application.