Abstract: Novel magnesium-based compositions-of-matter which can be used for manufacturing implantable medical devices such as orthopedic implants are disclosed. The compositions-of-matter can be used for constructing monolithic, porous and/or multilayered structures which are characterized by biocompatibility, mechanical properties and degradation rate that are highly suitable for medical applications. Articles, such as medical devices, made of these magnesium-based compositions-of-matter and processes of preparing these magnesium-based compositions-of-matter are also disclosed.

Abstract: Surfaces play an important role in a biological system for most biological reactions occurring at surfaces and interfaces. The development of biomaterials for tissue engineering is to create perfect surfaces which can provoke specific cellular responses and direct new tissue regeneration. The improvement in biocompatibility of biomaterials for tissue engineering by directed surface modification is an important contribution to biomaterials development. Among many biomaterials used for tissue engineering, polyesters have been well documented for their excellent biodegradability, biocompatibility and nontoxicity. However, poor hydrophilicity and the lack of natural recognition sites on the surface of polyesters have greatly limited their further application in the tissue engineering field. Therefore, how to introduce functional groups or molecules to polyester surfaces, which ideally adjust cell/tissue biological functions, becomes more and more important. In this review, recent advances in polyester surface modification and their applications are reviewed. The development of new technologies or methods used to modify polyester surfaces for developing their biocompatibility is introduced. The results of polyester surface modifications by surface morphological modification, surface chemical group/charge modification, surface biomacromolecule modification and so on are reported in detail. Modified surface properties of polyesters directly related to in vitro/vivo biological performances are presented as well, such as protein adsorption, cell attachment and growth and tissue response. Lastly, the prospect of polyester surface modification is discussed, especially the current conception of biomimetic and molecular recognition.

Abstract: Polyelectrolyte microcapsules are made by layer-by-layer (LbL) coating of a sacrificial template, followed by decomposition of the template, to produce hollow microcapsules. In this paper, we report on the in vivo cellular uptake, degradation and biocompatibility of polyelectrolyte microcapsules produced from alternating dextran sulphate and poly-L-arginine layers on a template of calcium carbonate microparticles. We show that a moderate tissue reaction is observed after subcutaneous injection of polyelectrolyte microcapsules in mice. Within sixteen days after subcutaneous injection, most of the microcapsules are internalized by the cells and start to get degraded. The number of polyelectrolyte layers determines the stability of the microcapsules after cellular uptake.

Abstract: PEG-containing copolymers play a prominent role as biomaterials for different applications ranging from drug delivery to tissue engineering. These custom-designed materials offer enormous possibilities to change the overall characteristics of biomaterials by improving their biocompatibility and solubility, as well as their ability to crystallize in polymer blends and to resist protein adsorption. This article demonstrates various principles of PEG-based material design that are applied to fine tune the properties of biomaterials for different tissue engineering applications. More specifically, strategies are described to develop PEG copolymers with various block compositions and specific bulk properties, including low melting points and improved surface hydrophilicity. Highly hydrated polymer gel networks for promoting cellular growth or suppressing protein adsorption and cell adhesion are introduced. By incorporating selectively cleavable cross-links, these hydrophilic polymers can also serve as smart hydrogel scaffolds, mimicking the natural extracellular matrix for cell cultivation and tissue growth. Ultimately, these developments lead to the creation of biomimetic materials to immobilize bioactive compounds, allowing precise control of cellular adhesion and tissue growth.

Abstract: A novel architecture was designed by combining the biocompatibility of chitosan (CS) and excellent conductivity of carbon nanofiber (CNF). The controllable electrodeposition of soluble CNF-doped CS colloidal solution formed a robust CNF−CS nanocomposite film with good biocompatibility for the immobilization and cytosensing of K562 cells on an electrode. The formed architecture was characterized using scanning electron microscopic, infrared spectrum, contact angle, and thermogravimetric analyses. The adhesion of K562 cells on the nanocomposite film-modified electrode could be followed with electrochemical impedance spectroscopy and cyclic voltammetry. The presence of CNF facilitated the electrochemical behavior of K562 cells. The impedance of electronic transduction was related to the amount of the adhered cells, producing a highly sensitive impedance sensor for K562 cells ranging from 5 × 103 to 5.0 × 107 cells mL-1 with a limit of detection of 1 × 103 cells mL-1. This work suggested a strategy to prepare...

Abstract: The use of strontium-containing hydroxyapatite (Sr-HA) as a biomaterial has been reported recently. In vitro and in vivo studies have shown that Sr-HA promotes osteoblast response and stimulates new bone formation. In order to extend its usage to major load-bearing applications, such as artificial hip replacement, it has been proposed that the material could be used in the form of a coating on implant surfaces. This paper reports a preliminary study of biocompatibility of plasma sprayed Sr-HA coatings on a metallic substrate. Coatings of Sr-HA containing 10 mol% Sr2+ was produced on titanium alloy substrates. The coating exhibited good bonding with the substrate. The bioactivity of Sr-HA coating was evaluated in vitro by immersion in simulated body fluid (SBF). After immersion in SBF, Sr-HA coating exhibited great ability to induce apatite precipitation on its surface. The possible effects of cell–materials interactions of Sr-HA coating were examined by culturing osteoprecursor cells (OPC1) on coating surfaces. The effect of Sr-HA was also compared to a hydroxyapatite (HA) coating, which is widely used in orthopedics and dentistry. The results indicated that Sr-HA coating had good biocompatibility with human osteoblasts. OPC1 cells survived and proliferated well on the surface of coating. Sr-HA coating promoted OPC1 cells attachment, and more local contacts were produced on the surface. The presence of Sr stimulated OPC1 cell differentiation and ALP expression. No deleterious effect on ECM formation and mineralization was found with Sr-HA coating. The results indicated that Sr-HA coating had good mechanical properties and bioactivity in vitro.

Abstract: Uncertainty over the potential detrimental effects of engineered nanomaterials on human health and the environment has fueled public debate and the push for additional regulatory oversight. For single-walled carbon nanotubes (SWNTs) the published data citing in vitro toxicity are particularly inconsistent and widely disputed. The underlying reasons for the discrepancies can be attributed to two causes: first, the wide variability in sample preparation and “purification” methods, including incomplete characterization of the SWNT materials following purification, such as minimal description about their post-purification solution behavior; and second, the use of nonuniform characterization methods and materials with different preparative protocols, viability assessment methods, and cell/species populations. Unfortunately, both points have rarely been addressed simultaneously in the literature and consequently have led to the wide variety of results. Even for well developed and optimized experimental protocols, insufficient characterization of samples makes identification of the toxic parameter(s) exceedingly difficult. Further complicating the elucidation of the physical properties causing in vitro and in vivo toxicity with SWNT materials is the wide distribution of tube diameters, lengths, and chiralities produced by current synthesis methods. Definitive discrimination of relative and synergistic effects with respect to these differences will continue to be impossible without implementation of precise measurements, complete characterization, and the use of well-defined materials. One of the main sources of the variation in the published toxicity and biocompatibility data is the wide variability in SWNT dispersion, which results from many different preparative protocols and methods. While there is broad agreement that biological studies should put more emphasis on detailed characterization of test nanomaterials, the role of the dispersion state as a definitive factor influencing the cellular exposure and response to the SWNTs has often been ignored. Given a constant dosage, differences in dispersion ranging from macroscopic aggregates to micrometer-scale clusters, bundles of multiple nanotubes or individually dispersed nanotubes will dramatically affect the absolute size and amount of surface area of the nanotube material to which the cells are exposed. Our previous work has demonstrated that different SWNT preparation methods yield materials possessing varying degrees of dispersion, with one common result being networks of tubes that do not readily exchange once clustered. Notable, however, is the use of small molecule surfactants to induce SWNT solubility and dispersion in aqueous solutions. Dispersion protocols involving surfactants are attractive, as the incorporation of the nanotube inside a surfactant shell does not appreciably alter the graphitic structure and desirable physicochemical properties of the SWNTs. However, many surfactant dispersions are only partially effective at dispersing SWNT material, and thus yield suspensions of aggregates and not singly dispersed nanotubes. Recently, DNA, peptides, and carbohydrates have been used in this surfactant/ wrapping polymer role and have been demonstrated to suspend SWNTs, with high individual dispersion of the nanotubes. These dispersions, in the case of DNA, are even stable enough to allow for separation of the dispersed material into well-defined subpopulations of the SWNTs. Recent reports have highlighted successes in separating polydisperse SWNT populations into well-defined length and chirality fractions using gel chromatography, size exclusion chromatography (SEC), ion chromatography (IC), or various forms of electrophoresis. This sorting affords opportunities to explore which fractions and/or properties in particular are contributing to the cellular toxicity. Herein we describe our efforts in generating well-dispersed, separated-length fractions by SEC, the exhaustive characterization of these fraction populations, and high-concentration in vitro toxicity data, which indicate a threshold on the length and corresponding toxicity of SWNTs that are uptaken into cells. Dispersion of SWNTs in aqueous solutions typically involves some detergent formulation and sonication protocol for both separating and suspending SWNT aggregates in solution. For our aqueous preparations, DNA wrapping was used as it imparts high-concentration solubility, successfully disperses individual SWNTs, and does not significantly alter the C O M M U N IC A IO N

Abstract: A low-temperature solution approach (90-95 degrees C) using FeCl(3) and urea was carried out to synthesize beta-FeOOH nanorods in aqueous solution. The as-synthesized beta-FeOOH nanorods were further calcined at 300 degrees C to form porous nanorods with compositions including both beta-FeOOH and alpha-Fe(2)O(3). The derived porous nanorods were engineered to assemble with four layers of polyelectrolytes (polyacrylic acid (PAA)/polyethylenimine(PEI)/PAA/PEI) on their surfaces as polyelectrolyte multilayer nanocapsules. Fluorescein isothiocyanate (FITC) molecules were loaded into the polyelectrolyte multilayer nanocapsules in order to investigate drug release and intracellular delivery in Hela cells. The as-prepared nanocapsules showed ionic strength-dependent control of the permeability of the polyelectrolyte shells. The release behavior of the entrapped FITC from the FITC-loaded nanocapsules exhibited either controlled- or sustained-release trends, depending on the compactness of the polyelectrolyte shells on the nanorod surfaces. Cytotoxicity measurements demonstrate that the native nanorods and the polymer-coated nanorods have excellent biocompatibility in all dosages between 0.1 ng mL(-1) and 100 microgm L(-1). The time dependence of uptake of FITC-loaded nanocapsules by Hela cancer cells observed by laser confocal microscopy indicates that the nanocapsules can readily be taken up by cancer cells in 15 min, a relatively short period of time, while the slow release of the FITC from the initial perimembrane space into the cytoplasm was followed by release into the nucleus after 24 h.

Abstract: Antimicrobial nanofibers of poly(ϵ-caprolactone) (PCL) were prepared by electrospinning of a PCL solution with small amounts of silver-loaded zirconium phosphate nanoparticles (nanoAgZ) for potential use in wound dressing applications. The electrospun nanoAgZ-containing PCL nanofibers were characterized using field emission scanning electron microscopy, energy dispersive X-ray spectrum (EDX), X-ray diffraction analysis (XRD), antimicrobial tests, and biocompatibility tests. The SEM, EDX, and XRD investigations of the electrospun fibers confirmed that silver-containing nanoparticles were incorporated and well dispersed in smooth and beadless PCL nanofibers. The results of the antimicrobial tests showed that these fibers have maintained the strong killing abilities of Ag+ existed in the nanoAgZ against the tested bacteria strains and discoloration has not been observed for the nanofibers. To test the biocompatibility of nanofibers as potential wound dressings, primary human dermal fibroblasts (HDFs) were cultured on the nanofibrous mats. The cultured cells were evaluated in terms of cell proliferation and morphology. The results indicated that the cells attached and proliferated as continuous layers on the nanoAgZ-containing nanofibers and maintained the healthy morphology of HDFs. The earlier results suggested that nanoAgZ-containing fibers may be expected to be a novel material for potential wound dressing applications because of the significant bacteriostatic activities and good biocompatibility. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007

Abstract: Background: Silicone implants are being used increasingly worldwide, especially in breast augmentation procedures. The most common morbidity observed is capsular contracture, which occurs in 15 percent of cases. To overcome this problem, the authors have developed a novel nanocomposite based on polyhedral oligomeric silsesquioxane-poly(carbonate-urea) urethane (POSS-PCU) for use as tissue implants.Methods: These polymers were implanted in six healthy sheep (n = 6) for 36 months and a siloxane served as the positive control. After explantation, these polymers were extracted, as was the surrounding capsule, if any. Attenuated total reflectance Fourier transform infrared spectroscopy analysis was performed to look for signs of surface degradation on the polymers and histopathologic and electron microscopic examinations were performed to study the interaction between the biomaterial and the host environment in greater detail.Results: After implantation, the authors observed minimal inflammation of the nanocomposite within the sheep model as compared with the siloxane control. Contact angle measurements and fibrinogen enzyme-linked immunosorbent assay tests were then conducted on the POSS-PCU nanocomposite to determine the reason for this behavior. The increased fibrinogen adsorption on POSS-PCU, its amphilicity, and large contact-angle hysteresis indicated that POSS-PCU inhibits inflammation by adsorbing and inactivating fibrinogen on its surface. In complete contrast, the control siloxane in the same setting demonstrated very significant inflammation and degradation, resulting in capsular formation. Naturally, there was no evidence of degradation of the nanocomposite compared with the siloxane control.Conclusions: POSS-PCU nanocomposites have enhanced interfacial biocompatibility and better biological stability as compared with conventional silicone biomaterials, thus making them safer as tissue implants.

Abstract: Non-woven poly(epsilon-caprolactone) (PCL) nanofibers were prepared by electrospinning and type-I collagen was then immobilized on the nanofibers after surface modification by remote plasma treatment. A collagen-coated surface was observed and characterized using scanning electron microscopy (SEM), contact-angle measurement and X-ray photoelectron spectroscopy (XPS). The results confirmed the successful immobilization of collagen on the nanofibers and the great improvement of surface wettability due to coating. The amounts of immobilized collagen were also measured by colorimetry. The results showed that remote plasma treatment can provide higher immobilization of collagen than conventional plasma. Primary human dermal fibroblasts (HDFs) were cultured to evaluate the biocompatibility of collagen-immobilized electrospun PCL nanofibers. The results of MTT testing and SEM showed that collagen immobilization can obviously enhance the attachment spreading and proliferation of HDFs compared with the pristine material. The collagen-immobilized non-woven PCL nanofibers can be expected to be a potential scaffold material for tissue engineering.

Abstract: A polyacrylic acid film was synthesized on titanium substrates from aqueous solutions via an electroreductive process for the first time. This work was done in order to develop a versatile coating for titanium-based orthopaedic implants that acts as both an effective bioactive surface and an effective anti-corrosion barrier. The chemical structure of the PAA coating was investigated by X-ray photoelectron spectroscopy (XPS). Scanning electron microscopy (SEM) was employed to evaluate the effect of annealing treatment on the morphology of the coatings in terms of their uniformity and porosity. Inductively coupled plasma mass spectrometry was used to measure ion concentrations in ion release tests performed on Ti-6Al-4V sheets modified with PAA coatings (annealed and unannealed). Results indicate that the annealing process produces coatings that possess considerable anti-corrosion performance. Moreover, the availability and the reactivity of the surface carboxylic groups were exploited in order to graft biological molecules onto the PAA-modified titanium implants. The feasibility of the grafting reaction was tested using a single aminoacid residue. A fluorinated aminoacid was selected, and the grafting reaction was monitored both by XPS, using fluorine as a marker element, and via quartz crystal microbalance (QCM) measurements. The success of the grafting reaction opens the door to the synthesis of a wide variety of PAA-based coatings that are functionalized with selected bioactive molecules and promote positive reactions with the biological system interfacing the implant while considerably reducing ion release into surrounding tissues.

Abstract: The biocompatibility of polymer scaffolds as neural stem cell transplantation matrices has not yet been studied extensively. In this study, we evaluated the biocompatibility of various biodegradable polymers for neural stem cells. The biocompatibility tests were performed by culturing hippocampal progenitor cells (HiB5) on films of poly(lactic-co-glycolic acid) (PLGA), poly(L-lactide-co-e-caprolactone) (PLCL) and poly(L-lactic acid) (PLLA) or in the presence of extracts from these polymers. Specifically, the viability, mitochondrial metabolic activity, proliferation, apoptosis and neurite out-growth of HiB5 cells were examined in biocompatibility tests. Among the tested polymers, PLGA performed best with respect to cell viability, mitochondrial metabolic activity and apoptotic activity. Compared to the other polymers, PLLA showed the worst results in all categories evaluated. PLGA also showed favorable results for neurite out-growth of HiB5 cells. The results of this study demonstrate the promising biocom...