摘要:

AbstractWe have studied the surface chemistry of two lots of Biomer™ (BSP067 and BSUAOOl), and widely used commercial poly(ether urethane) (PEU). Although transmission infrared adsorption studies revealed no differences in the bulk chemistry of the two lots, the surface chemistry, as seen by x‐ray photoelectron spectroscopy (XPS) and static secondary ion mass spectrometry (SIMS), was different. Lot BSP067 showed softsegment enrichment at the surface, which is typical of PEU. Lot BSUAOOl showed no evidence of either hard‐ or soft‐segment PEU components at the surface. The surface of this lot was completely covered with a nonextractable additive identified as poly(diisopropy1 amino ethyl methacrylate). Small amounts of a low‐molecular‐weight antioxidant were observed at the surface of both samples. Because the biological response to polymers is dependent on surface structure, these results are of considerable importance to biomateria

ISSN:0021-9304    

DOI:10.1002/jbm.820260302

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractThe nature of the contact sites formed during the adhesion of osteoblasts to orthopedic implant materials was investigated by fluorescence microscopy. More specifically, the cytoskeletal organization of and the focal contact formation by neonatal rat calvarial osteoblasts attaching to and spreading on 316L stainless steel, Ti‐6A1– 4V, Co–Cr–Mo, Synamel (hydroxyapatite), alumina, and borosilicate glass were examined. Focal contacts are regions where the plasma membrane approaches the substrate to within 10–15 nm and where bundles of cytoskeletal microfilaments terminate. Fluorescent‐labeling of F–actin– containing microfilaments demonstrated a typical sequence of events as rounded, suspended osteoblasts spread onto the substrates. Immunofluorescent‐labeling of the protein vinculin, which is found at the cytoplasmic face of focal contacts, initially showed the formation of streak‐like focal patches. On the biomaterials, the vinculin staining subsequently extended up and along, but ventral to, the microfilament bundles. The fibrillar patterns observed at later times may evidence the formation of extracellu

ISSN:0021-9304    

DOI:10.1002/jbm.820260303

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractDuring arthrotomy, desiccation of the articular cartilage of synovial joints by the ambient environment of the operating room causes chondrocyte death and may promote degenerative changes within the joint. This study documents the efficacy of a biomaterial, hyaluronan (HY) solution, to maintain chondrocyte viability during desiccation. Rabbit patellar articular cartilage was air‐dried for 2 h with and without application of the HY solution. As assessed by35S04uptake and autoradiography, the HY solution helped maintain chondrocyte viability, when compared to air dried specimens (p ≤ 0.02). HY solution applied to the articular surfaces of joints undergoing arthrotomy may offset the detrimental effects of desiccation, such as chondrocyte death and degenerative joint chan

ISSN:0021-9304    

DOI:10.1002/jbm.820260304

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractThe surface chemistry, oxidation, and dissolution kinetics of titanium were measured to establish the mechanisms of passive dissolution in physiological environments. Titanium thin films were immersed in 8.0 mM ethylenediamine‐ tetraacetic acid in simulated interstitial electrolyte (EDTA/SIE) and maintained at 37°C, 10% O2, 5% CO2and 7.2 pH for periods of time up to 3200 h (133 days). Two immersion schemes were employed: the integral sequentially determined the titanium released into a solution of accumulated dissolution products; and the differential continuously replenished the test solution. The solutions were analyzed for titanium by electrothermal atomic absorption spectrometry (EAAS), and the sample surfaces were analyzed by Auger electron spectroscopy (AES) and x‐ray photoelectron spectroscopy (XPS) to determine oxide composition, stoichiometry, and thickness. Prior to immersion two types of hydroxyl (OH) groups were distinguished on the TiO2surface. Upon immersion, the chemistry of the surface changed as a function of immersion: the presence of OH groups increased and P (nonelemental) was detected at the surface. The dissolution kinetics obeyed a two‐phase logarithmic model, where the transition between phases occurred simultaneously with the adsorption of the P‐containing species. The dissolution kinetics depended on surface reactions, electric field strength, and molecular diffusion. These mechanisms explain the observed dependence of dissolution kinetics on the properties of the surface oxide and solution

ISSN:0021-9304    

DOI:10.1002/jbm.820260305

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractColony assay using V79 cells, the agar diffusion assay with L929 cells, and the 7‐day rabbit muscle implantation test were employed to evaluate the cytotoxicity and tissue toxicity of natural rubber latex (NRL) materials. Thein vivoimplantation test showed that, among 13 histological parameters, thickness of inflammatory layer was the most useful index to evaluate tissue responses quantitatively. A comparison of thein vivoand in nitro parameters revealed the following correlations between the thickness of the inflammatory layer and cytotoxicity indices: Colony assay of the extracts, IC50: r = 0.80; Agar diffusion assay, Zone index: r = 0.73; Lysis index: r = 0.61. From these results, it appears that the colony assay provides a more reliable prediction of the tissue response than the agar diffusion assa

ISSN:0021-9304    

DOI:10.1002/jbm.820260306

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractClinical applications of small‐diameter synthetic vascular grafts are hindered by their highly thrombogenic surfaces. To develop vascular grafts that resist thrombotic occlusion, a radio frequency glow discharge (RFGD) process was employed to modify the surface of existing graft materials. Ultrathin coatings of RFGD polymers of ethylene (E), tetrafluoroethylene (TFE), and hexamethyldisiloxane (HMDS) were deposited on the lumen of Dacron grafts. Surfaces were characterized by electron spectroscopy for chemical analysis (ESCA). The effect of glow discharge treatments on plateletgraft interactions was evaluated in anex vivobaboon shunt model. Following placement of an untreated or RFGD‐ treated graft in the shunt, deposition of111Indium‐labeled platelets was monitored for 60 min by γ camera imaging. Untreated Dacron rapidly accumulated large numbers of platelets, reaching a plateau i n 60 min. HMDS‐ and TFE‐treated Dacron had significantly lower levels of platelet deposition compared to the untreated control. In contrast, the ethylene treatment of Dacron augmented platelet deposition, making it the most platelet‐ adherent surface studied.In vitrostudies were also performed using untreated and RFGD‐treated poly (ethylene terephthalate) (PET) coverslips. ESCA verified that the surface composition of the untreated and RFGD‐treated coverslips were virtually identical to their untreated and treated Dacron graft counterparts. Samples were incubated in washed baboon platelet suspensions for 2 h at 37°C. Platelet adhesion on the untreated PET was relatively high, and many of the platelets had a completely spread morphology. The HMDS and TFE treatment of PET reduced the number of adherent platelets and prevented platelet spreading on the surface. Platelet adhesion and spreading on the ethylene‐treated surface was the highest among the four studied. There is a remarkable linear correlation of theex vivoandin vitropla

ISSN:0021-9304    

DOI:10.1002/jbm.820260307

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractPhotoreactive poly(ethy1ene glycol) (PEG) was synthesized by reacting 4‐fluoro‐ 3‐nitrophenyl azide (FNPA) with sodium salt of PEG. The synthesized 4‐azido‐2‐ nitrophenyl PEG (ANP‐PEG) was charac‐ terized by1H‐NMR, IR, and UV spectro‐ scopy. ANP‐PEG was grafted to dimethyldichlorosilane‐coated glass (DDS‐glass) by photolysis without any premodification of the surface. The effects of various grafting factors, such as the polymer adsorption time, concentration of ANP‐PEG, and UV irradiation time, on the PEG grafting efficiency were examined. The PEG‐grafted DDS‐glass was characterized by measuring surface free energies, surface‐induced platelet activation, and the relative amount of PEG grafted on the surface using electron spectroscopy for chemical analysis (ESCA). Platelet adhesion and activation was analyzed by measuring the number and spread area of adherent platelets. The results showed that ANP‐PEG had to be adsorbed onto DDS‐glass for at least 12 h before photolysis for the maximum grafting efficiency. No platelets could adhere to the PEG‐grafted DDS‐glass, if the bulk concentration of ANP‐PEG in the adsorption solution was between 1 mg/mL and 10 mg/mL. Above 10 mg/mL, platelet activation gradually increased and reached the maximum at 30 mg/mL. Our data indicate that the grafting of ANP‐PEG requires careful control of the grafting conditions and that the grafted PEG ca

ISSN:0021-9304    

DOI:10.1002/jbm.820260308

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

摘要:

AbstractSynthetic elastomeric polypeptide matrices based on the repeating amino acid sequences of elastin have biophysical and biological properties which are favorable for prosthetic materials. An important requirement envisaged for some applications is the ability to support cell adhesion and growth. The X20–poly– (GVGVP), the γ–irradiation cross‐linked elastomeric matrix based on the repeatin poly[n(GVGVP), (GRGDSP)] containing the covalently incorporated cell adhesion sequence Arg–Gly–Asp–Ser (RGDS) were synthesized. These matrices were tested for their ability to support the adhesion and growth of bovine aortic endothelial cells and of bovine ligamentum nuchae fibroblasts. Adhesion experiments carried pentamer Val–Pro–Gly–Val–Gly, and X2 B – out in albumin‐containing media showed that matrices containing 60:1, 40:1, and 20:l ratios of (GVGVP):(GRGDSP) supported maximal cell attachment, that matrices containing 100:l exhibited an intermediate level of attachment and that matrices composed of 500:l and (GVGVP) alone were very poor supports for cell attachment. Serum in the media promoted submaximal cell attachment to X20–poly– (GVGVP) but did not permit substantial cell growth. Cell growth was supported by matrices having high ratios of (GRGDSP). Ratios of 60:1, 40:1, and 2O:l supported three population doublings of endothelial cells over 3 days resulting in confluent matrix‐adherent monolayers. Ratios of 40:l and 20:l similarly sup

ISSN:0021-9304    

DOI:10.1002/jbm.820260309

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY

ISSN:0021-9304    

DOI:10.1002/jbm.820260301

出版商:John Wiley&Sons, Inc.    

年代:1992

数据来源: WILEY