Kuhlman William, Taniguchi Ikuo, Griffith Linda G, Mayes Anne M
Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Biomacromolecules. 2007 Oct;8(10):3206-13. doi: 10.1021/bm070237o. Epub 2007 Sep 18.
The effects of tether length on cell adhesion to poly(methyl methacrylate)-graft-poly(ethylene oxide), PMMA-g-PEO, comb copolymer films functionalized with the adhesion peptide RGD were investigated. Copolymers having PEO tether lengths of 10 and 22 EO segments were synthesized and coupled with a synthetic peptide that contained both RGD and the synergy sequence PHSRN. Cell spreading assays revealed that the longer polymer tethers increased the rate of spreading and reduced the time required for fibroblasts to form focal adhesions. Fluorescence resonance energy transfer (FRET) measurements indicated a mean separation between integrin-bound peptides of 15.6 +/- 1.4 nm for combs with long (22-mer) tethers, compared with 17.5 +/- 1.3 nm for short (10-mer) tethers, on films of comparable peptide density (approximately 2500 peptides/microm2). The results suggest that the added mobility afforded by the more extensible tethers encouraged the formation of focal adhesions by allowing cells to reorganize tethered peptides on the nanometer length scale. In addition, adhesion peptides were selectively coupled to 10-mer or 22-mer PEO tethers within a bimodal brush to investigate stratification effects on cell adhesion. Peptides bound by short tethers in a bed of long unsubstituted chains resulted in surfaces that resisted, rather than promoted, cell adhesion. By contrast, when long peptide tethers were employed with short unsubstituted chains, cell attachment and spreading were comparable to that found on a monomodal brush of long chains at equivalent peptide density.
研究了拴系长度对细胞黏附于用黏附肽RGD功能化的聚（甲基丙烯酸甲酯）-接枝-聚（环氧乙烷）（PMMA-g-PEO）梳型共聚物薄膜的影响。合成了具有10个和22个环氧乙烷链段拴系长度的共聚物，并与一种同时包含RGD和协同序列PHSRN的合成肽偶联。细胞铺展试验表明，较长的聚合物拴系增加了铺展速率，并减少了成纤维细胞形成黏着斑所需的时间。荧光共振能量转移（FRET）测量表明，在肽密度相当（约2500个肽/μm²）的薄膜上，对于长（22聚体）拴系的梳型共聚物，整联蛋白结合肽之间的平均间距为15.6±1.4 nm，而对于短（10聚体）拴系的梳型共聚物，该间距为17.5±1.3 nm。结果表明，更具延展性的拴系所提供的额外流动性通过允许细胞在纳米长度尺度上重新组织拴系的肽，促进了黏着斑的形成。此外，将黏附肽选择性地偶联到双峰刷中的10聚体或22聚体PEO拴系上，以研究分层对细胞黏附的影响。在长的未取代链层中由短拴系结合的肽导致表面抵抗而不是促进细胞黏附。相比之下，当长肽拴系与短的未取代链一起使用时细胞附着和铺展与在相同肽密度下长链单峰刷上的情况相当。
