摘要:

Cell-biomaterial interaction is of great importance for the development of bioinert as well as of hybrid surfaces. This study represents our results of human fibroblast interaction with PEG-coated surfaces of differing length and structure (linear or branched) of the oxyethylene chain. We employed three PEGs - PEG 1500 and PEG 6000, both linear but with different chain lengths, and PEG 12 500 which was branched. The PEGs were deposited on silica plates using branched poly(ethylene imine) as an anchoring polymer. Fibroblasts were plated and studied by immunofluorescence to evaluate the overall cell morphology, the organisation of the actin cytoskeleton, and the β1-integrin (fibronectin receptor). The particular effect of fibronectin (FN) pre-adsorption was studied. Our results suggest that PEG 6000 surface is to be preferable with respect to the initial interaction with the cells. The overall cell morphology was almost normal on bare surfaces. FN pre-coating additionally improved cell adhesion and spreading as well as the organization of the actin cytoskeleton and focal adhesion formation; the PEG 12 500 surface showed relatively poor initial properties. Almost no cell spreading was found on the bare surface, but FN pre-adsorption completely restored normal cell morphology. In contrast, PEG 1500 had to be considered as 'the worst' material, because of lower initial cell adhesion and spreading and FN pre-adsorption did not restore normal cell morphology.

ISSN:0920-5063    

DOI:10.1163/156856299X00838

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

This paper describes the synthesis and biodegradation of copolymers of cyclic depsipeptide with ε-caprolactone (CL) or lactide (LA). Optically active cyclic depsipeptides, 3,6-dimethyl-2,5-morpholinediones (DMOs), were prepared by the reaction of an amino acid (D-, L-, or DL-alanine) with a hydroxy acid derivative (DL-2-bromopropionyl bromide). These isomers are abbreviated as D-DMO, L-DMO and DL-DMO respectively, according to the names of alanine isomers. Then, we have prepared the copolymers of DMO isomers with CL using tin(II) octylate as a catalyst. The NMR spectra and thermal properties of DMO/CL copolymers revealed that these copolymers exist randomly. The enzymatic degradation of the copolymers has been examined using Rhizopus delemar lipase, cholesterol esterase (from Pseudomonas sp.), and Proteinase K (from Tritirachium album). Cholesterol esterase and Proteinase K show high degradability, while the lipase shows little degradation. Among the enzymes used, only Proteinase K could recognize the isomerism of DMO, resulting in the following order of degradability: copoly(L-DMO/CL) > copoly(DL-DMO/CL) > copoly(D-DMO/CL), i.e. this enzyme has the highest substrate specificity for naturally occurring L-alanine. Further, we have prepared the random copolymers of L-DMO with lactide (L-LA or DL-LA), and evaluated the enzymatic degradation of the copolymers by Proteinase K. The introduction of a small amount (up to c. 10 mol%) of L-DMO unit into LA homopolymers brought about greater degradability compared with LA homopolymers. In particular, L-DMO/L-LA copolymers with high degradability have been obtained without significant decrease in the mechanical and thermal properties of L-LA homopolymer.

ISSN:0920-5063    

DOI:10.1163/156856299X00847

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

In membrane hybrid liver support devices (HLSDs) using isolated hepatocytes where oxygen is transported only by diffusion to the cells, about 15-40% of the cell mass is likely to be in direct contact with the semipermeable membranes used as immunoselective barriers: quantitative effects of membrane surface properties on the kinetics of hepatocyte metabolic reactions may also affect HLSD performance. In this paper, we report our investigation of the effects of surface morphology of two microporous commercial membranes on the kinetics of oxygen consumption and ammonia elimination by primary hepatocytes in adhesion culture. Isolated rat hepatocytes were cultured on polypropylene microporous membranes with different surface roughness and pore size in a continuous-flow bioreactor whose fluid dynamics was optimized for the kinetic characterization of liver cell metabolic reactions. Collagencoatcd membranes were used as the reference substratum. Hepatocyte adhesion was not significantly affected by membrane surface morphology. The rates of the investigated reactions increased with ammonia concentration according to saturation kinetics: the values of kinetic parameters Vmaxand KMincreased as cells were cultured on the membrane with the greatest membrane surface roughness and pore size. For the reaction of oxygen consumption, Vmaxincreased from 0.066 to 0.1 pmol h-1per cell as surface roughness increased from 70 to 370 nm. For the kinetics of ammonia elimination, KMincreased from 0.23 to 0.32 mM and Vmaxincreased from 1.49 to 1.79 pmol h-1per cell with membrane surface roughness increasing from 70 to 370 nm. Cells cultured on collagen-coated membranes consistently yielded the highest reaction rates. The Vmaxvalues of 0.18 and 2.84 pmol h-1per cell for oxygen consumption and ammonia elimination, respectively, suggest that cell functions are also affected by the chemical nature of the substratum.

ISSN:0920-5063    

DOI:10.1163/156856299X00856

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Poly(ether ether ketone) (PEEK) films were chemically modified, by surface wet chemistry, into PEEK-OH, PEEK-NH2, and PEEK-NCO. Fibronectin (FN) adsorption, in the presence or absence of two non-ionic surfactants, was compared onto PEEK, PEEK-OH, and PEEK-NH2on which the protein can only be adsorbed, and onto PEEK-NCO on which FN could be covalently grafted. The amounts of FN present on the various supports were assayed by ELISA and LSC (with125I-labeled FN). The remarkable effect of Pluronic F68 in preventing non-specific protein adhesion on the less hydrophilic surfaces was pointed out. Accordingly, a procedure could be proposed that allows minimal FN adhesion vs FN fixation on PEEK-NCO. The resulting PEEK-FN film, which immobilized 120-150 ng FN cm-2, constitutes a new substratum for cell cultivation.

ISSN:0920-5063    

DOI:10.1163/156856299X00865

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

The effect of fibrinogen and high molecular weight kininogen on bacterial adhesion to functionalized polyurethanes was studied. Glass slides were coated with different polyurethanes, including Pellethane, sulfonated Pellethane, phosphonated Pellethane, a zwitterionic phosphonated polyurethane, and quaternized amine polyurethanes. The polymer-coated glass squares were exposed to radiolabelled S. aureus. When comparing adhesion to bare polyurethanes, it was found that adhesion was lowest on the phosphonated Pellethane and the zwitterionic phosphonated polyurethane while highest on the methyl quaternized polyurethanes. Fibrinogcn-mcdiated adhesion was studied by first exposing the polymers to increasing concentrations of canine fibrinogen before incubating them with S. aureus. All the polymers except the quaternized amine polyurethanes exhibited at least ten-fold increases in bacterial adhesion as the fibrinogen treatment concentration was increased from 0.0 to 10.0 μg ml-1. The quaternized amine polyurethanes maintained their relatively high amount of bacterial adhesion regardless of the fibrinogen concentration. The effect of two-chain high molecular weight kininogen (TCHMWK) on fibrinogen-mediated bacterial adhesion was assessed by exposing the polymers to 1.0 μg ml-1fibrinogen followed by two different concentrations of TCHMWK. Decreases in bacterial adhesion were observed on all the polymcrs except the quaternized amine polyurethanes, which again retained their relatively high amount of bacterial adhesion.

ISSN:0920-5063    

DOI:10.1163/156856299X00874

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor