Evaluation of the biocompatibility of the GSH-coated Ag2S quantum dots in vitro: a perfect example for the non-toxic optical probes.

Near-infrared quantum dots (NIR QDs) are promising candidate for the fluorescent probes due to their better penetration depth, long-lived luminescence with size-tunable photoluminescence wavelengths. Glutathione-coated silver sulfide quantum dots (GSH-Ag2S QDs) were synthesized using AgNO3 and Na2S in the aqueous media and they can give reaction with glutathione reductase (GR) and glutathione-s transferase (GST) enzymes as acting substrate analogue in vitro. Investigation of the toxicity of the nanomaterials are necessary to use them in the medical field and biomedical applications. Thus, in this study we investigated biocompatibility of the GSH-Ag2S QDs in vitro using 293 T and CFPAC-1 cell lines. Cell viability by MTT assay, light microscopy, fluorescence microscopy, oxidative stress enzyme activities and ICP-MS analysis were performed to evaluate the cytotoxicity and internalization of the GSH-Ag2S QDs. GSH-Ag2S QDs showed great biocompatibility with both cell lines and did not cause imbalance in the oxidative stress metabolism. The ultralow solubility product constant of Ag2S QDs (Ksp = 6.3 × 10-50) prevents release of Ag ions into the biological systems that is in agreement with data obtained by ICP-MS. In conclusion, this data prove potential of GSH-Ag2S QDs as a biocompatible optical probe to be used for the detection and/or targeting of GSH impaired diseases including cancer.

Evaluation of reagents used to coat the hollow-fiber bioreactor membrane of the Quantum® Cell Expansion System for the culture of human mesenchymal stem cells.

The addition of a coating reagent to promote cell adherence is necessary to prepare the membrane surface of the Quantum® Cell Expansion System hollow-fiber bioreactor for the culture of mesenchymal stem cells. In this study, the efficacy of 8 potential coating reagents has been compared in terms of the doubling times of their cell populations, cell morphology, characterization via flow cytometry, and capacity for trilineage differentiation. Human fibronectin (FN), pooled human cryoprecipitate (CPPT), and recombinant human vitronectin (VN) were successful as coating reagents, and each product has advantages in different cell culture contexts. Mesenchymal stem cells harvested from Quantum cultured with each of these 3 compounds as coating reagents all met International Society for Cellular Therapy standards for plastic adherence, surface marker expression, and successful trilineage differentiation. No significant differences were observed among the doubling times from Quantum harvests using FN, CPPT, or VN as coating reagents (P = 0.31). Coating with gelatin, human serum albumin, collagen I, poly­l­lysine, and poly­d­lysine resulted in significantly lower harvest yield; these agents are not recommended for use as coating reagents in the Quantum system.

A bioactive coating with submicron-sized titania crystallites fabricated by induction heating of titanium after tensile deformations.

Thermal oxidation technology was widely investigated as one of effective surface modification method for improving the bioactivity and biocompatibility of titanium and its alloys. In this work, the induction heat oxidization method, a fast, efficient, economical and environmental protective technology, was applied to prepare the submicron-morphological oxide coating with variable rutile TiO2 equiaxed crystallites on the surface of pure Ti substrates after cold-drawing with 10-20% deformations. The results showed the plastic-deformed Ti cylinders recrystallized during induction heating treatment (IHT) for 10-20s which resulted in evolution of microstructures as well as slight improvement of microhardness. The surface characteristics of TiO2 crystallites in oxidation layers were determined by the microstructural evolutions of Ti substrate in terms of the nucleation and growth of TiO2 crystallites. Specially, the oxidized surface with 50-75nm roughness and more uniform and finer equiaxed oxide grains remarkablely improved the apatite deposition after bioactive evaluation in 1.5 × SBF for 7 days. This work provided a potential method to create controlled bioactive oxide coatings with submicro-/nano-scaled TiO2 crystallites on titanium substrate in terms of the role of metallographic microstructure in the formation process of titanium oxides.

Quantifying the mode II critical strain energy release rate of borate bioactive glass coatings on Ti6Al4V substrates.

Bioactive glasses have been used as coatings for biomedical implants because they can be formulated to promote osseointegration, antibacterial behavior, bone formation, and tissue healing through the incorporation and subsequent release of certain ions. However, shear loading on coated implants has been reported to cause the delamination and loosening of such coatings. This work uses a recently developed fracture mechanics testing methodology to quantify the critical strain energy release rate under nearly pure mode II conditions, GIIC, of a series of borate-based glass coating/Ti6Al4V alloy substrate systems. Incorporating increasing amounts of SrCO3 in the glass composition was found to increase the GIIC almost twofold, from 25.3 to 46.9J/m2. The magnitude and distribution of residual stresses in the coating were quantified, and it was found that the residual stresses in all cases distributed uniformly over the cross section of the coating. The crack was driven towards, but not into, the glass/Ti6Al4V substrate interface due to the shear loading. This implied that the interface had a higher fracture toughness than the coating itself.

Evaluation of Rosin Gum and Eudragit® RS PO as a Functional Film Coating Material.

Polymers are essential tools in the research and development of new therapeutic devices. The diversity and flexibility of these materials have generated high expectations in the composition of new materials with extraordinary abilities, especially in the design of new systems for the modified release of pharmaceutically active ingredients. The natural polymer rosin features moisture protection and pH-dependent behavior (i.e., it is sensitive to pH > 7.0), suggesting its possible use in pharmaceutical systems. The synthetic polymer Eudragit® RS PO is a low-permeability material, the disintegration of which depends on the time of residence in the gastrointestinal tract. The present study developed a polymeric material with desirable physicochemical characteristics and synergistic effects that resulted from the inherent properties of the associated polymers. Isolated films were obtained by solvent evaporation and subjected to a water vapor transmission test, scanning electron microscopy, calorimetry, Fourier transform-infrared (FT-IR) spectroscopy, micro-Raman spectroscopy, and mechanical analysis. The new polymeric material was macroscopically continuous and homogeneous, was appropriately flexible, had low water permeability, was vulnerable in alkaline environments, and was thermally stable, maintaining an unchanged structure up to temperatures of ∼400°C. The new material also presented potentially suitable characteristics for application in film coatings for oral solids, suggesting that it is capable of carrying therapeutic substances to distal regions of the gastrointestinal tract. These findings indicate that this new material may be added to the list of functional excipients.

Significance of in-situ dry-ice blasting on the microstructure, crystallinity and bonding strength of plasma-sprayed hydroxyapatite coatings.

To obtain hydroxyapatite (HA) coatings with high crystallinity which have long-term stability in clinical applications, coarse powders were usually injected to less energetic plasma. However, the HA coatings accumulated by partly melted particles usually have high porosity and poor mechanical properties, especially poor bonding strength. In this work, by profiting its quenching and mechanical impact, dry-ice blasting was in-situ employed during plasma spray process to improve the microstructure characterization and bonding strength of HA coatings. In addition, the influence of in-situ dry-ice blasting on the phase composition and crystallinity of plasma-sprayed HA coatings was investigated. The results show that a significant reduction of porosity and an apparent increase in bonding strength are revealed in plasma-sprayed HA coatings due to the cleaning effect of dry-ice blasting on the convex unmelted particles and splashing fragments. HA coatings prepared by the combination process of plasma spraying and dry-ice blasting have a compromise structure with minimum globular pores but with pronounced microcracks. The disappearance of CaO phase and the increase in crystallinity also derive from the application of dry-ice blasting.

Transparent antifouling material for improved operative field visibility in endoscopy.

Camera-guided instruments, such as endoscopes, have become an essential component of contemporary medicine. The 15-20 million endoscopies performed every year in the United States alone demonstrate the tremendous impact of this technology. However, doctors heavily rely on the visual feedback provided by the endoscope camera, which is routinely compromised when body fluids and fogging occlude the lens, requiring lengthy cleaning procedures that include irrigation, tissue rubbing, suction, and even temporary removal of the endoscope for external cleaning. Bronchoscopies are especially affected because they are performed on delicate tissue, in high-humidity environments with exposure to extremely adhesive biological fluids such as mucus and blood. Here, we present a repellent, liquid-infused coating on an endoscope lens capable of preventing vision loss after repeated submersions in blood and mucus. The material properties of the coating, including conformability, mechanical adhesion, transparency, oil type, and biocompatibility, were optimized in comprehensive in vitro and ex vivo studies. Extensive bronchoscopy procedures performed in vivo on porcine lungs showed significantly reduced fouling, resulting in either unnecessary or ∼10-15 times shorter and less intensive lens clearing procedures compared with an untreated endoscope. We believe that the material developed in this study opens up opportunities in the design of next-generation endoscopes that will improve visual field, display unprecedented antibacterial and antifouling properties, reduce the duration of the procedure, and enable visualization of currently unreachable parts of the body, thus offering enormous potential for disease diagnosis and treatment.

Effect of current density during electrodeposition on microstructure and hardness of textured Cu coating in the application of antimicrobial Al touch surface.

Copper is a well proven antimicrobial material which can be used in the form of a coating on the touch surfaces. Those coating can offer a good service as touch surface for very long time if only they possess good mechanical properties like scratch resistance and microhardness. In the present work the above mentioned mechanical properties were determined on the electrodeposited copper thin film; deposited on double zincated aluminium. During deposition, current density was varied from 2Adm(-2) to 10Adm(-2), to produce crystallite size in the range of 33.5nm to 66nm. The crystallite size was calculated from the X-ray peak broadening (Scherrer׳s formula) which were later confirmed by TEM micrographs. The scratch hardness and microhardness of the coating were measured and correlated with the crystallite size in the copper coating. Both characteristic values were found to increase with the reduction in crystallite size. Reduced crystallite size (Hall-Petch effect) and preferred growth of copper films along (111) plane play a significant role on the increase in the hardness of the coating. Further, TEM analysis reveals the presence of nano-twins in the film deposited at higher current density, which contributed to a large extent to the sharp increase of coating hardness compared to the mechanism of Hall-Petch effect. The antimicrobial ability of the coated sample has been evaluated against Escherichia coli bacteria and which is compared with that of commercially available bulk copper using the colony count method. 94% of E. coli cells were died after six hours of exposure to the copper coated surface. The morphology of the copper treated cells was studied using SEM.

Influence of Starting Powders on Hydroxyapatite Coatings Fabricated by Room Temperature Spraying Method.

Three types of raw materials were used for the fabrication of hydroxyapatite coatings by using the room temperature spraying method and their influence on the microstructure and in vitro characteristics were investigated. Starting hydroxyapatite powders for coatings on titanium substrate were prepared by a heat treatment at 1100 °C for 2 h of bovine bone, bone ash, and commercial hydroxyapatite powders. The phase compositions and Ca/P ratios of the three hydroxyapatite coatings were similar to those of the raw materials without decomposition or formation of a new phase. All hydroxyapatite coatings showed a honeycomb structure, but their surface microstructures revealed different features in regards to surface morphology and roughness, based on the staring materials. All coatings consisted of nano-sized grains and had dense microstructure. Inferred from in vitro experiments in pure water, all coatings have a good dissolution-resistance and biostability in water.

Quantitative analysis of PEG-functionalized colloidal gold nanoparticles using charged aerosol detection.

Surface characteristics of a nanoparticle, such as functionalization with polyethylene glycol (PEG), are critical to understand and achieve optimal biocompatibility. Routine physicochemical characterization such as UV-vis spectroscopy (for gold nanoparticles), dynamic light scattering, and zeta potential are commonly used to assess the presence of PEG. However, these techniques are merely qualitative and are not sensitive enough to distinguish differences in PEG quantity, density, or presentation. As an alternative, two methods are described here which allow for quantitative measurement of PEG on PEGylated gold nanoparticles. The first, a displacement method, utilizes dithiothreitol to displace PEG from the gold surface. The dithiothreitol-coated gold nanoparticles are separated from the mixture via centrifugation, and the excess dithiothreitol and dissociated PEG are separated through reversed-phase high-performance liquid chromatography (RP-HPLC). The second, a dissolution method, utilizes potassium cyanide to dissolve the gold nanoparticles and liberate PEG. Excess CN(-), Au(CN)2 (-), and free PEG are separated using RP-HPLC. In both techniques, the free PEG can be quantified against a standard curve using charged aerosol detection. The displacement and dissolution methods are validated here using 2-, 5-, 10-, and 20-kDa PEGylated 30-nm colloidal gold nanoparticles. Further value in these techniques is demonstrated not only by quantitating the total PEG fraction but also by being able to be adapted to quantitate the free unbound PEG and the bound PEG fractions. This is an important distinction, as differences in the bound and unbound PEG fractions can affect biocompatibility, which would not be detected in techniques that only quantitate the total PEG fraction.

An in vitro model of a system of electrical potential compensation in extracorporeal circulation.

OBJECTIVES: Extracorporeal circulation (ECC) in patients undergoing cardiac surgery induces systemic immune-inflammatory reaction that results in increased postoperative morbidity. Many factors are responsible for the adverse response after ECC. The present in vitro study aimed to investigate electric charges (ECs) generated during ECC, to set a device compensating the ECs, and checking its effect on red blood cells (RBC). MATERIALS AND METHODS: The electrical signals of blood in ECC were collected by a custom developed low-noise electronic circuit, processed by a digital oscilloscope (DSO) and a dynamic signal analyzer (DSA). The compensation of ECs was performed using a compensation device, injecting a nulling charge into the blood circuit. The compensation effect of the ECs on RBCs was evaluated by scanning electron microscope (SEM). RESULTS: The electrical analysis performed using both the DSO and the DSA confirmed the EC formation during ECC. The notable electric signals recorded in standard ECC circuits substantially nulled once the compensation device was used, thus confirming efficient EC compensation. After two hours of ECC, the SEM non-blended test on human RBC samples highlighted morphological changes in acanthocytes of the normal biconcave-shaped RBC. CONCLUSIONS: The outcomes confirm the development of parasitic ECs during ECC and that a suppressor system may decrease the potential damage of ECs. Nevertheless, further studies are ongoing in order to investigate the complex mechanisms related to lymphocytes and platelet morphological and physiological chances during triboelectric charges in ECC.

Early postsurgical visualization of composite mesh used in ventral hernia repair by amide proton transfer MRI.

PURPOSE: The feasibility of noninvasive visualization of composite meshes used in ventral hernia repair by amide-proton transfer magnetic resonance imaging (APT-MRI) was explored. METHODS: Magnetization transfer asymmetry ratio images of composite meshes were obtained in vitro and in vivo from fast-spin echo acquisitions with frequency saturation offsets of ±3.5 ppm with respect to water frequency and no saturation. Three rats were assessed with APT-MRI each week for 1 month after the intraperitoneal implantation of two meshes, one on each side of the incision. One mesh was coated with collagen and the other was not. RESULTS: In vitro, meshes were delineated with APT-MRI as a thin continuous linear hypersignal located on one side of the mesh. Unlike collagen-free meshes, collagen-coated meshes were easily identified in vivo with APT-MRI during the first 3 weeks postimplantation. The composite meshes magnetization transfer asymmetry ratio (8.7 ± 2.8%) were significantly different from the muscle magnetization transfer asymmetry ratio value (-0.9 ± 1.6%). After a month, the mesh value dropped down to 1.1 ± 3.9%. Muscle and mesh magnetization transfer asymmetry ratio values were not significantly different and mesh conspicuity was no longer possible. CONCLUSION: The results suggest that APT-MRI is a promising technique for noninvasive, early postsurgical visualization of composite meshes used in ventral hernia repair.

Grafting of poly(2-methacryloyloxyethyl phosphorylcholine) on polyethylene liner in artificial hip joints reduces production of wear particles.

Despite improvements in the techniques, materials, and fixation of total hip arthroplasty, periprosthetic osteolysis, a complication that arises from this clinical procedure and causes aseptic loosening, is considered to be a major clinical problem associated with total hip arthroplasty. With the objective of reducing the production of wear particles and eliminating periprosthetic osteolysis, we prepared a novel hip polyethylene (PE) liner whose surface graft was made of a biocompatible phospholipid polymer-poly(2-methacryloyloxyethyl phosphorylcholine (MPC)). This study investigated the wear resistance of the poly(MPC)-grafted cross-linked PE (CLPE; MPC-CLPE) liner during 15×10(6) cycles of loading in a hip joint simulator. The gravimetric analysis showed that the wear of the acetabular liner was dramatically suppressed in the MPC-CLPE liner, as compared to that in the non-treated CLPE liner. Analyses of the MPC-CLPE liner surface revealed that it suffered from no or very little wear even after the simulator test, whereas the CLPE liners suffered from substantial wears. The scanning electron microscope (SEM) analysis of the wear particles isolated from the lubricants showed that poly(MPC) grafting dramatically decreased the total number, area, and volume of the wear particles. However, there was no significant difference in the particle size distributions, and, in particular, from the SEM image, it was observed that particles with diameters less than 0.50µm were present in the range of the highest frequency. In addition, there were no significant differences in the particle size descriptors and particle shape descriptors. The results obtained in this study show that poly(MPC) grafting markedly reduces the production of wear particles from CLPE liners, without affecting the size of the particles. These results suggest that poly(MPC) grafting is a promising technique for increasing the longevity of artificial hip joints.

Mechanical and tribological behavior of silicon nitride and silicon carbon nitride coatings for total joint replacements.

Total joint replacements currently have relatively high success rates at 10-15 years; however, increasing ageing and an active population places higher demands on the longevity of the implants. A wear resistant configuration with wear particles that resorb in vivo can potentially increase the lifetime of an implant. In this study, silicon nitride (SixNy) and silicon carbon nitride (SixCyNz) coatings were produced for this purpose using reactive high power impulse magnetron sputtering (HiPIMS). The coatings are intended for hard bearing surfaces on implants. Hardness and elastic modulus of the coatings were evaluated by nanoindentation, cohesive, and adhesive properties were assessed by micro-scratching and the tribological performance was investigated in a ball-on-disc setup run in a serum solution. The majority of the SixNy coatings showed a hardness close to that of sintered silicon nitride (~18 GPa), and an elastic modulus close to that of cobalt chromium (~200 GPa). Furthermore, all except one of the SixNy coatings offered a wear resistance similar to that of bulk silicon nitride and significantly higher than that of cobalt chromium. In contrast, the SixCyNz coatings did not show as high level of wear resistance.

Fatigue property of a bioabsorbable magnesium alloy with a hydroxyapatite coating formed by a chemical solution deposition.

A hydroxyapatite (HAp) coating was directly formed on an extruded AZ31 magnesium alloy by a single-step chemical solution deposition. The HAp coating consists of an outer porous HAp layer, an inner continuous HAp layer, and a thin intermediate MgO layer, and the inner HAp and MgO layers are composed of nanocrystals. Tensile and fatigue tests were performed on the HAp-coated AZ31 in air. The HAp coating microscopically showed neither crack nor detachment at 5% static elongation (1.5% residual strain). With further elongation under tensile stress, cracks were formed perpendicularly to the tensile direction, and fragments of the coating detached with a fracture inside the inner continuous HAp layer. The fatigue strengths at 10(7) cycles (fatigue limit) of HAp-coated and mechanically polished AZ31 were ca. 80 MPa and ca. 90 MPa, respectively. The slight decrease in the fatigue limit with the HAp coating is attributed to small pits with a depth of ca. 10 µm formed on the substrate during the HAp-coating treatment. The HAp coating remained on the specimen without cracks after 10(7) cycles at the fatigue limit, which provides ca. 3% cyclic elongation.

An innovative, easily fabricated, silver nanoparticle-based titanium implant coating: development and analytical characterization.

Microbial colonization and biofilm formation on implanted devices represent an important complication in orthopaedic and dental surgery and may result in implant failure. Controlled release of antibacterial agents directly at the implant site may represent an effective approach to treat these chronic complications. Resistance to conventional antibiotics by pathogenic bacteria has emerged in recent years as a major problem of public health. In order to overcome this problem, non-conventional antimicrobial agents have been under investigation. In this study, polyacrylate-based hydrogel thin coatings have been electrosynthesised on titanium substrates starting from poly(ethylene glycol diacrylate)-co-acrylic acid. Silver nanoparticles (AgNPs) with a narrow size distribution have been synthesized using a "green" procedure and immobilized on Ti implant surfaces exploiting hydrogel coatings' swelling capabilities. The coatings have been characterized by XPS and SEM/EDX, while their silver release performances have been monitored by ICP-MS. The antibacterial activity of these AgNP-modified hydrogel coatings was tested evaluating in vitro inhibition growth of Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli, among the most common pathogens in orthopaedic infections. Moreover, a preliminary investigation of the biocompatibility of silver-loaded coatings versus MG63 human osteoblast-like cells has been performed. An important point of strength of this paper, in fact, is the concern about the effect of silver species on the surrounding cell system in implanted medical devices. Silver ion release has been properly tuned in order to assure antibacterial activity while preserving osteoblasts' response at the implant interface.

Evaluation of collagen/heparin coated TCP/HA granules for long-term delivery of BMP-2.

Bone morphogenetic proteins (BMPs) are the most potent osteoinductive growth factors. However, a delivery system is essential to take advantage of the osteoinductive effect of BMPs. The purpose of this study was to develop a sustained delivery system for recombinant human bone morphogenetic protein-2 (BMP-2). We covalently attached heparin to a cross-linked collagen type I coated tricalciumphosphate/hydroxyapatite (TCP/HA) bone substitute and subsequently loaded it with BMP-2. To systematically evaluate the contribution of each component with respect to the binding and release of BMP-2, six constructs were prepared and characterized: TCP/HA, TCP/HA with collagen (TCP/HACol), and TCP/HA with collagen and heparin (TCP/HAColHep) with and without BMP-2 (B). More BMP-2 bound to the TCP/HAColHep + B (92.9 ± 4.8 ng BMP-2/mg granule) granules as compared to the TCP/HACol + B (69.0 ± 9.6 ng BMP-2/mg granule) and TCP/HA + B granules (62.9 ± 5.4 ng BMP-2/mg granule). No difference in release pattern was found between the TCP/HA + B and TCP/HACol + B granules. Up to day 14, BMP-2 was still bound to the TCP/HAColHep + B granules, whereas most BMP had been released from TCP/HACol + B and TCP/HA + B granules at that time. After 21 days most BMP-2 also had been released from the TCP/HAColHep + B granules. The local and sustained delivery system for BMP-2 developed in this study may be useful as a carrier for BMP-2 and could possibly enhance bone regeneration efficacy for the treatment of large bone defects.

Modification of TiO(2) nanotube surfaces by electro-spray deposition of amoxicillin combined with PLGA for bactericidal effects at surgical implantation sites.

OBJECTIVE: To fabricate the antibiotic-releasing coatings on TiO(2) nanotube surfaces for wide applications of implant and bone plate in medical and dental surgery, the optimal deposition time of amoxicillin/PLGA solution simultaneously performing non-toxicity and a high bactericidal effect for preventing early implant failures was found. MATERIALS AND METHODS: FE-SEM, ESD and FT-IR were used for confirming deposition of amoxicillin/PLGA on the TiO(2) surface. Also, the elution of amoxicillin/PLGA in a TiO(2) nanotube surface was measured by a UV-VIS spectrophotometer. The bactericidal effect of amoxicillin on the TiO(2) nanotube surface was evaluated by using Staphylococcus aureus (S. aureus). The cytotoxicity and cell proliferation were observed by WST assay using MC3T3-E1 osteoblast cells. RESULTS: The results indicated that the TiO(2) nanotube surface controlled by electro-spray deposition time with amoxicillin/PLGA solution could provide a high bactericidal effect against S. aureus by the bactericidal effect of amoxicillin, as well as good osteoblast cell proliferation at the TiO(2) nanotube surface without toxicity. CONCLUSIONS: This study used electro-spray deposition (ESD) methodology to obtain amoxicillin deposition in nanotube structures of TiO(2) and found the optimal deposition time of amoxicillin/PLGA solution simultaneously performing non-toxicity and a high bactericidal effect for preventing early implant failures.

Effect of strontium-substituted nanohydroxyapatite coating of porous implant surfaces on implant osseointegration in a rabbit model.

PURPOSE: This study investigated the effects of a strontium-substituted nanohydroxyapatite (Sr-HA) coating, deposited onto porous implant surfaces using an electrochemical process, on implant osseointegration in a rabbit model. MATERIALS AND METHODS: The surfaces were analyzed by field-emission scanning electron microscopy, x-ray diffractometry (XRD), Fourier transform infrared spectroscopy (FT-IR), a portable surface roughness tester, and inductively coupled plasma atomic emission spectroscopy (ICP-AES). Thirty implants (half HA-coated and half Sr-HA-coated) were inserted into femurs of 15 rabbits. After 2, 4, and 8 weeks, the femurs were retrieved and prepared for histomorphometric evaluation. RESULTS: Microscopic examination showed a surface topography of rodlike crystals on both surfaces. XRD and FT-IR showed that the phase of the deposits was HA. No differences were found in surface roughness between the two groups. ICP-AES showed that the Sr/(Ca+Sr) molar ratio of Sr-HA coating was 10.1 mol%. Histologic observation showed that new bone appeared on both surfaces after 2 weeks and became mature after 8 weeks. Histomorphometric analysis showed no differences between the two groups in bone-to-implant contact at 2 weeks or in bone area within all threads at 2 and 4 weeks. The Sr-HA coated group had significantly higher bone-to-implant contact at 4 and 8 weeks. Significant differences were also found in bone area at 8 weeks. CONCLUSION: The present study showed that this Sr-HA coating, deposited using an electrochemical process, has the potential to enhance implant osseointegration.

In vivo solid-phase microextraction for tissue bioanalysis.

Conventional in vitro or ex vivo bioanalytical quantitative sample preparation methods for the determination of compounds in biological tissues are often coupled with challenges in obtaining an assay representative of the system of interest. The rising interest in in vivo microsampling bioanalytical methods is due to the unique advantages they offer over their in vitro counterparts. In vivo solid-phase microextraction (SPME), a diffusion-based microsampling tool, has been successfully applied in recent studies to various biological systems. This review presents recent trends in tissue bioanalysis using in vivo SPME as a sample preparation tool. Efforts were made to discuss the various bioapplications of the method while highlighting possible strategies for improved sensitivity where needed. In vivo SPME devices currently employed for the various applications have also been described. In addition, we highlight selectivity of a new class of biocompatible coatings that can potentially improve the coverage of metabolites for untargeted metabolomics.