Journal of Biomedical Materials Research - Part B Applied Biomaterials

Poly(ethylene oxide) (PEO) coatings have been shown to reduce the adhesion of different microbial strains and species and thus are promising as coatings to prevent biomaterial‐centered infection of medical implants. Clinically, however, PEO coatings are not yet applied, as little is known about their stability and effectiveness in biological fluids. In this study, PEO coatings coupled to a glass substratum through silyl ether bonds were exposed for different time intervals to saliva, urine, or phosphate‐buffered saline (PBS) as a reference at 37°C. After exposure, the effectiveness of the coatings against bacterial adhesion was assessed in a parallel plate flow chamber. The coatings appeared effective against Staphylococcus epidermidis adhesion for 24, 48, and 0.5 h in PBS, urine, and saliva, respectively. Using XPS and contact‐angle measurements, the variations in effectiveness could be attributed to conditioning film formation. The overall short stability results from hydrolysis of the coupling of the PEO chains to the substratum. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater

The aim of this study was to measure degree of conversion (DC) of resin‐based composites (RBCs) using micro‐Raman spectroscopy followed by different sample preparation procedures and storing conditions. Ninety samples of Tetric EvoCeram (Ivoclar Vivadent, Schaan, Liechtenstein) were prepared in standardized molds and cured with a high powered LED light‐curing unit, bluephase® (Ivoclar Vivadent, Schaan, Liechtenstein) for 20 s. Samples were allocated to eight groups. DC of groups 1 and 2 was recorded without or after polishing. DC in groups 3 and 4 was recorded from vertically sectioned samples versus “split” samples. DC in groups 5–8 was recorded after storing samples at room temperature and humidity, in 90 ± 2% humidity at 37 ± 1°C, distilled water at 37 ± 1°C or buffered incubation medium (BIM) at 37 ± 1°C for 24 h. Mean values of DC in polished and unpolished samples were 63.6% (±3.2%) and 54.7% (±5.2%), respectively (p < 0.0001). There was no significant difference in DC after sample‐sectioning (p > 0.05). Significantly higher DC values were obtained after storing samples in BIM (76.8% ± 2.1%) than in distilled water (59.7% ± 5.7%), extreme humidity (60.3% ± 3.9%) or in room conditions (63.6% ± 3.2%) (p < 0.001). DC of an RBC measured by micro‐Raman spectroscopy may be affected by differences in sample preparation and storing conditions, making it difficult to extrapolate data from in vitro studies into clinically relevant information. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008

In this study, a slurry foaming method was developed to fabricate porous titanium, and two different surface treatments were applied to investigate their effects on the osteoinduction of the implants. Three types of implants, that was porous titanium with no treatment, with chemical‐thermal treatment (CTPT), and with acid‐alkali treatment (AAPT), were implanted in the dorsal muscles of adult dogs for 3 and 5 months. After implantation for 3 months, new bone was only found in the inner pores of AAPT by histological analysis and field emission scanning electron microscopy observation. After implantation for 5 months, new bone was also found in CTPT, but it was absent in AAPT. This study not only confirmed that porous titanium with appropriate surface treatments could possess osteoinduction but also showed that its osteoinductive potential was tightly related to the surface treatment. As a simpler method, acid‐alkali treatment could endow porous titanium with faster osteoinduction, and AAPT might have potential in clinical application. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010.

In this study, an attempt was made to develop an understanding of the densification behavior, phase stability, and biocompatibility property of HA‐CaTiO₃ biocomposite. The composites with varying CaTiO₃ (40–80 wt %) content were sintered at temperatures ranging from 1200°C to 1500°C for 3–5 hr to establish optimum processing parameters. The phase analysis using spectral techniques indicate good thermochemical compatibility between HA and CaTiO₃. The microstructural observations reveal homogeneous distribution of finer CaTiO₃ phase (1–2 μm) along with coarser calcium phosphate phase. In vitro cell culture studies using L929 mouse fibroblast and SaOS2 human osteoblast cell lines provide clear evidence of cell adhesion, spreading, and proliferation as well as the formation of cellular bridges, and, hence, good in vitro biocompatibility of the developed composite can be realized. Also, the number of viable cells was found to increase with incubation period, as revealed by statistical analysis of the 3(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay data. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010.

Zr‐based bulk metallic glasses (BMGs) possess attractive properties for prospective biomedical applications. The present study designs Ni‐free Zr–Cu–Al–Nb–Pd BMGs and investigates their in vitro biocompatibility by studying mechanical properties, bio‐corrosion resistance, and cellular responses. The Ti–6Al–4V alloy is used as a reference material. It is found that the Zr‐based BMGs exhibit good mechanical properties, including high strengths above 1600 MPa, high hardness over 4700 MPa, and low elastic moduli of 85–90 GPa. The Zr‐based BMGs are corrosion resistant in a simulated body environment, as revealed by wide passive regions, low passive current densities, and high pitting overpotentials. The formation of ZrO₂‐rich surface passive films of the Zr‐based BMGs contributes to their high corrosion resistance, whereas their pitting corrosion in the phosphate buffered saline solution can be attributed to the sensitivity of the ZrO₂ films to the chloride ion. The general biosafety of the Zr‐based BMGs is revealed by normal cell adhesions and cell morphologies. Moreover, the Zr/Cu content ratio in the alloy composition affects the biocompatibility of the Zr‐based BMGs, by increasing their corrosion resistance and surface wettability with the increase of the Zr/Cu ratio. Effects of Zr/Cu ratios can be used to guide the future design of biocompatible Zr‐based BMGs. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 100B: 1472–1482, 2012.

Despite the beneficial properties and outstanding potential of hydrogels for biomedical applications, several unmet challenges must be overcome, especially regarding to their known sensitivity to conventional sterilization methods. It is crucial for any biomaterial to withstand an efficient sterilization to obtain approval from regulatory organizations and to safely proceed to clinical trials. Sterility assurance minimizes the incidence of medical device‐related infections, which still constitute a major concern in health care. In this review, we provide a detailed and comprehensive description of the published work from the past decade regarding the effects of sterilization on different types of hydrogels for biomedical applications. Advances in hydrogel production methods with simultaneous sterilization are also reported. Terminal sterilization methods can induce negative or positive effects on several material properties (e.g., aspect, size, color, chemical structure, mechanical integrity, and biocompatibility). Due to the complexity of factors involved (e.g., material properties, drug stability, sterilization conditions, and parameters), it is important to note the virtual impossibility of predicting the outcome of sterilization methods to determine a set of universal rules. Each system requires case‐by‐case testing to select the most suitable, effective method that allows for the main properties to remain unaltered. The impact of sterilization methods on the intrinsic properties of these systems is understudied, and further research is needed. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2472–2492, 2018.

This study investigates the microstructure, mechanical properties, corrosion behavior, and biocompatibility of magnesium (Mg)‐based Mg1Zr2SrxDy (x = 0, 1, 1.63, 2.08 wt %) alloys for biodegradable implant applications. The corrosion behavior of the Mg‐based alloys has been evaluated in simulated body fluid using an electrochemical technique and hydrogen evolution. The biocompatibility of the Mg‐based alloys has been assessed using SaSO2 cells. Results indicate that the addition of Dy to Mg‐Zr‐Sr alloy showed a positive impact on the corrosion behavior and significantly decreased the degradation rates of the alloys. The degradation rate of Mg1Zr2Sr1.0Dy decreased from 17.61 to 12.50 mm year⁻¹ of Mg1Zr2Sr2.08Dy based on the hydrogen evolution. The ultimate compressive strength decreased from 270.90 MPa for Mg1Zr2Sr1Dy to 236.71 MPa for Mg1Zr2Sr2.08Dy. An increase in the addition of Dy to the Mg‐based alloys resulted in an increase in the volume fraction of the Mg₂Dy phase, which mitigated the galvanic effect between the Mg₁₇Sr₂ phase and the Mg matrix, and led to an increase in the corrosion resistance of the base alloy. The biocompatibility of the Mg‐based alloys was enhanced with decreasing corrosion rates. Mg1Zr2Sr2.08Dy exhibited the lowest corrosion rate and the highest biocompatibility compared with the other Mg‐based alloys. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 2425–2434, 2018.

Cellular behavior can be influenced by the chemical and physical surface characteristics of biomedical substrates. To understand the relationships between various topographical surface patterns and cellular activities, various types of pattern models have been developed and examined in a range of sizes (microscale, nanoscale, and hierarchical structures consisting of both) and shapes (pillar, hole, groove, grate, grid, and island). Here, we review fabrication methods for obtaining physically patterned microscale and nanoscale surfaces, and discuss the relationships between cellular responses and physically patterned surfaces, which could be applied to various biomedical scaffolds used in tissue engineering applications. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 102B: 1580–1594, 2014.

The purpose of the present study was to compare wear particles isolated from metal–metal (MM) hip implants worn in an orbital bearing simulator with particles from similar MM total hip replacement (THR) implants worn in vivo. Comparison of these particles is important because it will help to assess the overall suitability of this type of hip simulator for reproducing in vivo wear and for producing physiological wear particles suitable for biological studies of in vitro cellular response. Commercial grade components made of ASTM F75 (cast) alloy were evaluated. Simulator tests were performed in 95% bovine calf serum with a 28‐mm‐diameter implant. Wear particles were collected from 0 to 0.25 million cycles (run‐in wear period) and 1.75 to 2 million cycles (steady‐state wear period). Tissues from seven patients with MM implants (surface replacement or stem type) were harvested at revision surgeries (after 1–43 months). Metal wear particles were isolated from serum lubricant or tissues using an enzymatic protocol that was previously optimized to minimize particle changes due to reagents. After isolation, particles were centrifuged, embedded in epoxy resin, and characterized by transmission electron microscopy (TEM) and energy dispersive X‐ray analysis (EDXA). Results of EDXA on particles from the hip simulator primarily indicated a predominance of particles containing Cr and O but no Co (most likely chromium oxide particles), and fewer CoCrMo particles presenting varying ratios of Co and Cr. Image analysis of TEM micrographs demonstrated that the majority of the particles from the simulator were round to oval, but a substantial number of needle‐shaped particles were also found, especially from 0 to 0.25 Mc. The particles generated from 0 to 0.25 Mc had an average length of 53 nm, whereas those generated from 1.75 to 2 Mc had an average length of 43 nm. In vivo, EDXA and TEM analysis of particles that were retrieved from two patients at 23 and 43 months respectively, revealed that they were the most comparable in composition, average length (57 nm), and shape to particles generated in the hip simulator during the run‐in wear period. Because a large clinical retrieval study in the literature suggested that a run‐in wear regime might occur in vivo for some 6–36 months, the fidelity of the simulator of the present study was strongly supported. However, some uncertainties existed, including the finding that the particles isolated from the other five patients generated from 1 month up to 15 months (shorter implantation times than the other two patients) were smaller and mostly contained only Cr and O (no Co). In the opinion of the authors, this particular very short term patient group was somewhat atypical. Therefore, despite these uncertainties, the present study was deemed to support the ability of the orbital bearing hip simulator to produce physiological wear particles. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 70B: 167–178, 2004

There is currently much discussion about the most clinically relevant testing methods for evaluating total hip replacements. This study examined the effect of different swing phase loads, including microseparation, on the wear, friction, and wear particles of metal‐on‐metal (MOM) hip replacements. MOM hip replacements were tested for 5 million cycles with the use of a hip simulator; prostheses were tested with a low (100‐N) and ISO (280‐N) swing phase load, and under microseparation conditions. Increasing the swing phase load from 100 to 280 N in the same hip simulator increased the wear of the MOM hip replacements by over tenfold. Introducing microseparation into the gait cycle increased wear further, and stripe wear was observed on the femoral heads, accompanied by corresponding rim damage on the acetabular cups. No significant difference in wear particle size was observed between wear particles produced by low load and microseparation hip simulator conditions. Introducing microseparation into the hip simulator gait cycle increased the wear of MOM prostheses. Joint laxity and separation may lead to increased wear rates of MOM prostheses in vivo. Additionally elevated positive swing phase loads may also increase wear. Variable swing phase load conditions in vivo may contribute to variations in clinical wear rates. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 70B: 233–239, 2004