bluuebunny/crossref_metadata_2025_split huggingface dataset:
Alginate/lactose‐modified chitosan hydrogels: A bioactive biomaterial for chondrocyte encapsulation
Authors: Marsich Eleonora , Borgogna Massimiliano , Donati Ivan , Mozetic Pamela , Strand Berit L. , Salvador Santiago Gomez , Vittur Franco , Paoletti Sergio 
Published: July 2007

AbstractA new bioactive scaffold was prepared from a binary polysaccharide mixture composed of a polyanion (alginate) and a polycation (a lactose‐modified chitosan, chitlac). Its potential use for articular chondrocytes encapsulation and cartilage reconstructive surgery applications has been studied. The hydrogel combines the ability of alginate to act as a 3D supporting structure with the capability of the second component (chitlac) to provide interactions with porcine articular chondrocytes. Physico‐chemical characterization of the scaffold was accomplished by gel kinetics and compression measurements and demonstrated that alginate‐chitlac mixture (AC‐mixture) hydrogels exhibit better mechanical properties when compared with sole alginate hydrogels. Furthermore, biochemical and biological studies showed that these 3D scaffolds are able to maintain chondrocyte phenotype and particularly to significantly stimulate and promote chondrocyte growth and proliferation. In conclusion, the present study can be considered as a first step towards an engineered, biologically active scaffold for chondrocyte in vitro cultivation, expansion, and cell delivery. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Reduced medical infection related bacterial strains adhesion on bioactive RGD modified titanium surfaces: A first step toward cell selective surfaces
Authors: Maddikeri R.R. , Tosatti S. , Schuler M. , Chessari S. , Textor M. , Richards R.G. , Harris L.G. 
Published: July 2007

AbstractIdeally, implants should inhibit nonspecific protein adsorption, bacterial adhesion, and at the same time, depending on the final application be selective toward cellular adhesion and spreading for all or only selected cell types. Poly(L‐lysine)‐grafted‐poly(ethylene glycol) (PLL‐g‐PEG) polymers have been shown to adsorb from aqueous solution onto negatively charged metal oxide surfaces, reducing protein adsorption as well as fibroblast, osteoblast and epithelial cell adhesion significantly. PLL‐g‐PEG can be functionalized with bioligands such as RGD (Arg‐Gly‐Asp), which then restores host cell adhesion, but the surface remains resistant to nonspecific protein adsorption. Previously, it was also shown that both nonfunctionalized PLL‐g‐PEG and RGD‐peptide functionalized PLL‐g‐PEG reduced the adhesion of Staphylococcus aureus to titanium (Ti) surfaces. The present study looked at the effect of other implant associated infection relevant bacteria, Staphylococcus epidermidis, Streptococcus mutans and Pseudomonas aeruginosa towards the same surface chemistries. The different surfaces were exposed to the bacteria for 1–24 h, and bacteria surface density was evaluated using scanning electron microscopy (SEM) and fluorescence light microscopy (FM). The adhesion of all bacteria strains tested was reduced on Ti surfaces coated with PLL‐g‐PEG compared to uncoated Ti surfaces even in the presence of RGD. The percentage reduction in bacterial adhesion over the 24‐h culture time investigated was 88%–98%, depending on the bacteria type. Therefore, coating surfaces with PLL‐g‐PEG/PEG‐RGD allows cells such as fibroblasts and osteoblasts to attach but not bacteria, resulting in a selective biointeractive pattern that may be useful on medical implants. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Characterization of polyelectrolyte multilayer films on polyethylene terephtalate vascular prostheses under mechanical stretching
Authors: Rinckenbach Simon , Hemmerlé Joseph , Dieval Florence , Arntz Youri , Kretz Jean‐Georges , Durand Bernard , Chakfe Nabil , Schaaf Pierre , Voegel Jean‐Claude , Vautier Dominique 
Published: July 2007

AbstractLayer‐by‐layer (LBL) polyelectrolyte films offer extensive potentials to enhance surface properties of vascular biomaterials. From the time of implantation, PET prostheses are continuously subjected to multiple mechanical stresses such as important distorsions and blood pressure. In this study, three LBL films, namely (1) poly(sodium 4‐styrenesulfonate)/poly(allylamine hydrochloride), (2) poly(L‐lysine)/hyaluronan, and (3) poly(L‐lysine)/poly(L‐glutamic acid) were built on to isolated PET filaments, thread, and vascular prostheses. The three LBL films uniformly covered the surface of the PET samples with rough, totally smooth, and “wrinkled” appearances respectively for (PAH/PSS)24, (PLL/HA)24, and (PLL/PGA)24 systems. We then assessed the behavior of these LBL films, in an aqueous environment [by environmental scanning electronic microscopy (ESEM)], when subjected to unidirectional longitudinal stretches. We found that stretching induces ruptures in the multilayer films on isolated filaments for longitudinal stretches of 14% for (PSS/PAH)24, 13% for (PLL/PGA)24, and 30% for (PLL/HA)24 films. On threads, the rupture limit is enhanced to be respectively 26, 20, and 28%. Most interestingly, we found that on vascular prosthesis no rupture is visible in any of the three multilayers types, even for elongations of 200% (200% undergone by the PET prostheses is representative of those encountered during graft deployment) which by far exceeds elongations observed under physiological conditions (10–20%, blood pressure). In term of mechanical behaviors, these preliminary data constitute a first step toward the possible use of LBL film to coat and functionalize vascular prosthesis. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Magnetic targeting after femoral artery administration and biocompatibility assessment of superparamagnetic iron oxide nanoparticles
Authors: Ma Hui‐Li , Qi Xian‐Rong , Ding Wu‐Xiao , Maitani Yoshie , Nagai Tsuneji 
Published: July 2007

AbstractFerrofluids are attractive candidates for magnetic targeting system because of their fluidity and magnetism. The magnetic nanoparticles in ferrofluids should have combined properties of superparamagnetic behavior, target localization, and biocompatibility. The magnetic targeting and biocompatibility of superparamagnetic iron oxide nanoparticles stabilized by alginate (SPION‐alginate) was investigated in vitro and in vivo. The localization of SPION‐alginate by an external magnetic field in vitro was quantitatively evaluated by determining the iron content, and the results revealed that the localization ratio of SPION‐alginate was 56%. Magnetic targeting of the SPION‐alginate after femoral artery administration with the magnetic field in rats was quantitatively investigated by iron content and qualitatively confirmed by histological evaluation and magnetic resonance imaging. The ratio of iron content between the target site and the nontarget site were 8.88 at 0.5 h and 7.50 at 2 h, respectively. The viability of RAW264.7 cells and L929 cells was apparently unaltered upon exposure to SPION‐alginate. The incubation with erythrocytes indicated that the SPION‐alginate did not induce erythrocytes hemolysis and aggregation. In conclusions, the SPION‐alginate had magnetic targeting with an external magnetic field and did not be detained at the injection site without the magnetic field. The SPION‐alginate was generally considered to be biocompatible in cytotoxicity and hemolysis aspects. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Acute oral toxicity evaluation of biodegradable and pH‐sensitive hydrogel based on polycaprolactone, poly(ethylene glycol) and methylacrylic acid (MAA)
Authors: Chen Xian , Qian ZhiYong , Gou MaLing , Chao GuoTao , Zhang YangDe , Gu YingChun , Huang MeiJuan , Wang JiWei , Pan YiFeng , Wei YuQuan , Chen JianPing , Tu MingJing 
Published: July 2007

AbstractIn this article, a novel biodegradable and pH‐sensitive hydrogel based on polycaprolactone, poly(ethylene glycol) and methylacrylic acid (MAA), was prepared by UV‐initiated free radical polymerization. The obtained hydrogel was characterized by 1H NMR and FTIR. The acute toxicity tests and histopathological study were performed in BALB/c mice. In acute oral toxicity test, mice were orally administered with a total 15 g/kg body weight (b.w.) of P(CL‐MAA‐EG) hydrogels, and were observed continuously for 14 days. For histopathologic study, samples including heart, liver, lung, kidneys, spleen, stomach, and intestine, were histochemically prepared and stained with hematoxylin‐eosin for histopathologic examination. No mortality or significant signs of acute toxicity was observed during the whole observation period, and no macroscopic alteration was found in the organs. Histopathological analysis of various organs also did not show any significant pathological changes. Thus, the maximal tolerance dose of P(CL‐MAA‐EG) hydrogels was calculated to be higher than 15 g/kg b.w. in BALB/c mice. It was suggested that the studied P(CL‐MAA‐EG) hydrogel in this article were nontoxic after acute oral administration and it might be a promising candidate as a novel oral drug carrier. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
A study on polysialic acid as a biomaterial for cell culture applications
Authors: Stark Yvonne , Bruns Stephanie , Stahl Frank , Kasper Cornelia , Wesemann Maike , Grothe Claudia , Scheper Thomas 
Published: July 2007

AbstractPolysialic acid (PSA) was investigated for its applicability as coating material for mammalian cell cultivation. PSA is involved in post‐translational modification of the vertebrate neural cell adhesion molecule (NCAM). It is biocompatible and degradation‐controlled. Thus, it becomes interesting for use as a coating and scaffold material for tissue engineering applications, especially for peripheral nerve regeneration. As a preliminary study of the use of PSA as scaffold material it was tested in its soluble form as coating material. The cytotoxicity was investigated and compared to another polysaccharide β‐glucan, to widely used coating substances (collagen I, poly‐L‐lysine, hyaluronic acid) and uncoated tissue culture plastic material. The interactions between the modified cell culture surface and the cells were investigated using a model liver cell line Hep‐G2 and a neurobiological cell line PC‐12. The PSA coating itself was analyzed by immunoanalysis. Viability of the cells was investigated by the MTT assay. The number and distribution of adhered cells were studied by cell nuclei staining. Furthermore, the differentiation status of the PC‐12 cells was monitored, as well as glucose and lactate levels in the cell culture medium from the Hep‐G2 cells. Comparable viability and similar numbers of attached cells were observed. Growth in cell clusters was observed for PSA, β‐glucan, and hyaluronic acid coated materials. In general, the results indicate that PSA is comparable to other well‐established coating materials (e.g. collagen I, hyaluronic acid, and poly‐L‐lysine). Moreover, as a key substance in vertebrate development it offers interesting features for nerve regeneration, especially as an insoluble, modified scaffold material. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
In vitro biological evaluation of β–TCP/HDPE—A novel orthopedic composite: A survey using human osteoblast and fibroblast bone cells
Authors: Homaeigohar S. SH. , Shokrgozar M. A. , Khavandi A. , Sadi A. Yari 
Published: July 2007

AbstractBeta‐tricalcium phosphate reinforced high density polyethylene (β‐TCP/HDPE) was prepared to simulate bone composition and to study its capacity to act as bone tissue. This material was produced by replacing the mineral component and collagen soft tissue of the bone with β‐TCP and HDPE, respectively. The biocompatibility of the composite samples with different volume fractions of TCP (20, 30 and 40 vol %) was examined in vitro using two osteoblast cell lines G‐292 and Saos‐2, and also a type of fibroblast cell isolated from bone tissue, namely human bone fibroblast (HBF) by proliferation, and cell adhesion assays. Cell‐material interaction with the surface of the composite samples was examined by scanning electron microscopy (SEM). The effect of β‐TCP/HDPE on the behavior of osteoblast and fibroblast cells was compared with those of composite and negative control samples; polyethylene (PE) and tissue culture polystyrene (TPS), respectively. In general, the results showed that the composite samples containing β‐TCP as reinforcement supported a higher rate of proliferation by various bone cells after 3, 7, and 14 days of incubation compared to the composite control sample. Furthermore, more osteoblast cells were attached to the surface of the composite samples when compared to the composite control samples after the above incubation periods (p < 0.05), while in the case of HBF an equal or even higher number of cells adhered to PE was observed. The number of adhered osteoblast cells was almost equal and in some days even higher than the number of adhered cells on negative control sample, while in the case of fibroblast this difference was significantly higher than TPS (p < 0.05). Adhered cells presented a normal morphology by SEM and many of the cells were observed to be undergoing cell division. These findings indicate that β‐TCP/HDPE composites are biocompatible, nontoxic, and act to stimulate proliferation and adhesion of the cells, whether osteoblast or fibroblast. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Relationship between tissue stiffness and degree of mineralization of developing trabecular bone
Authors: Mulder Lars , Koolstra Jan Harm , den Toonder Jaap MJ , van Eijden Theo MGJ 
Published: July 2007

AbstractIt is unknown how the degree of mineralization of bone in individual trabecular elements is related to the corresponding mechanical properties at the bone tissue level. Understanding this relationship is important for the comprehension of the mechanical behavior of bone at both the apparent and tissue level. The purpose of the present study was, therefore, to determine the tissue stiffness and degree of mineralization of the trabecular bone tissue and to establish a relationship between these two variables. A second goal was to assess the change in this relation during development. Mandibular condylar specimens of four fetal and four newborn pigs were used. The tissue stiffness was measured using nanoindentation. A pair of indents was made in the cores of 15 trabecular elements per specimen. Subsequently, the degree of mineralization of these locations was determined from microcomputed tomography. The mean tissue stiffness was 11.2 GPa (±0.5 GPa) in the fetal group and 12.0 GPa (±0.8 GPa) in the newborn group, which was not significantly different. The degree of mineralization of the fetal trabecular cores was 744 mg/cm3 (±28 mg/cm3). The one in the newborn bone measured 719 mg/cm3 (±34 mg/cm3). Again, the difference was statistically insignificant. A significant relationship between tissue stiffness and degree of mineralization was obtained for fetal (R = 0.42, p < 0.001) and newborn (R = 0.72, p < 0.001) groups. It was concluded that woven bone tissue in fetal and newborn trabecular cores resembles adult trabecular bone in terms of tissue properties and is strongly correlated with degree of mineralization. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Cotton wool‐like nanocomposite biomaterials prepared by electrospinning: In vitro bioactivity and osteogenic differentiation of human mesenchymal stem cells
Authors: Schneider Oliver D. , Loher Stefan , Brunner Tobias J. , Uebersax Lorenz , Simonet Marc , Grass Robert N. , Merkle Hans P. , Stark Wendelin J. 
Published: July 2007

AbstractThe present study evaluates the in vitro biomedical performance of an electrospun, flexible, and cotton wool‐like poly(lactide‐co‐glycolide) (PLGA)/amorphous tricalcium phosphate (ATCP) nanocomposite. Experiments on in vitro biomineralization, applicability in model defects and a cell culture study with human mesenchymal stem cells (hMSC) allowed assessing the application of the material for potential use as a bone graft. Scaffolds with different flame made ATCP nanoparticle loadings were prepared by electrospinning of a PLGA‐based composite. Immersion in simulated body fluid showed significant deposition of a hydroxyapatite layer only on the surface of ATCP doped PLGA (up to 175% mass gain within 15 days for PLGA/ATCP 60:40). Proliferation and osteogenic differentiation of hMSC on different nanocomposites were assessed by incubating cells in osteogenic medium for 4 weeks. Proper adhesion and an unaffected morphology of the cells were observed by confocal laser scanning microscopy for all samples. Fluorometric quantification of dsDNA and analysis of ALP activity revealed no significant difference between the tested scaffolds and excluded any acute cytotoxic effects of the nanoparticles. The osteocalcin content for all scaffolds was 0.12–0.19 ng/ng DNA confirming osteogenic differentiation of human mesenchymal stem cells on these flexible bone implants. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2008
Thermal reactions of brushite cements
Authors: Bohner M. , Gbureck U. 
Published: July 2007

AbstractThe thermal reactions of a brushite cement made of β‐tricalcium phosphate (β‐TCP), monocalcium phosphate monohydrate (MCPM), and an aqueous solution were followed in situ with an isothermal calorimeter at 37°C. The investigated parameters were the β‐TCP/MCPM weight ratio, the liquid‐to‐powder ratio, the synthesis route and milling duration of the β‐TCP powder, as well as the presence of sulfate, citrate, and pyrophosphate ions in the mixing liquid. The thermograms were complex, particularly for mixtures containing an excess of MCPM or additives in the mixing solution. Results suggested that the endothermic MCPM dissolution and the highly exothermic β‐TCP dissolution occurred simultaneously, thereby leading to the formation of a large exothermic peak at early reaction time. Both reactions were followed by the exothermic crystallization of brushite and in the presence of an excess of MCPM by the endothermic crystallization of monetite. Additives generally widened the main exothermic reaction peak, or in some cases with pyrophosphate ions postponed the main exothermic peak at late reaction time. Generally, the results could be well explained and understood based on thermodynamic and solubility data. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Uniaxial and biaxial properties of terminally sterilized porcine urinary bladder matrix scaffolds
Authors: Freytes Donald O. , Stoner Richard M. , Badylak Stephen F. 
Published: July 2007

AbstractScaffolds composed of extracellular matrix have been successfully used to support the reconstruction of a variety of tissues in preclinical studies and in clinical applications. As an off‐the‐shelf product, extracellular matrix (ECM) scaffolds must be subjected to terminal sterilization before use. The choice of sterilization method may alter the integrity of the ECM's composition and structure such that the mechanical and material properties are adversely affected. The present study evaluated selected structural properties of an ECM scaffold derived from the urinary bladder termed urinary bladder matrix after being sterilized by three different methods: ethylene oxide (ETO) (750 mg/h for 16 h), gamma irradiation (2.0 Mrads), or electron beam irradiation (e‐beam) (2.2 Mrads). The structural properties that were evaluated include maximum force, maximum elongation, maximum tangential stiffness, energy dissipation, and ball‐burst strength. All sterilization methods affected at least two of the measured properties. ETO was shown to have the least detrimental effect upon the measured properties. Gamma and e‐beam irradiation were shown to decrease the uniaxial and biaxial strength, maximum tangential stiffness, and the energy dissipation of the ECM scaffolds. The present study showed that the choice of terminal sterilization method affects the structural properties of scaffolds composed of extracellular matrix. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2008
Chitosan coated alginate beads containing poly(N‐isopropylacrylamide) for dual‐stimuli‐responsive drug release
Authors: Shi Jun , Alves Natália M. , Mano João F. 
Published: July 2007

AbstractChitosan coated alginate beads containing poly(N‐isopropylacrylamide) (PNIPAAM), were prepared to be used as a controlled pH/temperature sensitive drug delivery system with improved encapsulation efficiency and delayed release rate. The studied beads were characterized by differential scanning calorimetry, scanning electron microscopy, and Fourier transform infrared spectroscopy. Water uptake and release studies using indomethacin as a model drug were also performed. The drug loading efficiency of the beads with the polyelectrolyte complex coating is significantly higher (84%) than that of the uncoated ones (74%). The equilibrium swelling of the developed materials was found to be pH‐ and thermo‐ responsive. For all the conditions it was found that the release profile was slower for the coated beads, indicating that the polyelectrolyte complex coating could slow down the release rate effectively. These results suggest that the studied smart system has potential to be used as an effective pH/temperature sustainable delivery system for biomedical applications. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Effects of load and indicator type upon occlusal contact markings
Authors: Saad Muhammad N. , Weiner Gabriel , Ehrenberg David , Weiner Saul 
Published: July 2007

AbstractStatement of Problem: Clinicians use occlusal indicators to identify tooth contacts. However, the reliability of these indicators has been questioned. At times occlusal contacts are not identified or false positive occlusal contacts are observed. Purpose of Study: This study was designed to compare the number and size of occlusal indicator marks from both thick and thin occlusal indicator materials with different loads. Materials and Methods: Ivorine casts were articulated and mounted on an Hana Mate nonadjustable articulator. Loads of 100N, 150N, and 200N were applied with Accufim (25 μm thick, Parkell, Farmingdale, NY) and Articulating Paper (60 μm thick, G.E. Rudischauer Dental Articulating Paper, Brooklyn, NY) as the occlusal indicators. A fresh piece of indicator was used for each trial. Comparisons were made of the number and size of the contacts for both the thick and thin occlusal indicators at the different loads. Results: Observation of the marks recorded with the thicker occlusal indicator demonstrated both a greater number marks and a larger size to the marks when compared to the thinner Accufilm, p ≤ 0.02–0.0001. However, there was no significant increase in the number or size of the marks with an increased load for either material. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008