The formation of protein concentration gradients mediated by density differences of poly(ethylene glycol) microspheres.
The formation of protein concentration gradients mediated by density differences of poly(ethylene glycol) microspheres.
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DOI：
10.1016/j.biomaterials.2010.07.085
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发表时间：
2010-11
期刊：
影响因子：
14
通讯作者：
Elbert, Donald L.
中科院分区：
文献类型：
--
作者：
Roam, Jacob L.;Xu, Hao;Nguyen, Peter K.;Elbert, Donald L.
组织工程支架形成的一个关键因素是引入生物活性分子的浓度梯度。我们探索了使用通过热致相分离制备的聚乙二醇（PEG）微球来促进支架中梯度的产生。产生具有不同密度（浮力）的PEG微球并离心以形成微球梯度。我们先前发现，相分离后的凝胶化时间控制去溶胀状态下微球的尺寸，而交联密度影响缓冲液交换到PBS中后的溶胀。这里用于控制微球密度的主要因素是PEG溶液在硫酸钠水溶液中相分离后反应的温度和高于“浊点”的孵育期的长度。使用不同的温度和孵育时间，形成在离心时自组装成梯度的微球。梯度是用尖锐的界面或逐渐的过渡产生的，最多有五层不同的微球类型。为了验证概念，还组装了共价固定的蛋白质的浓度梯度。还制备了含有肝素的PEG微球。将PEG-肝素微球与荧光标记的鱼精蛋白一起孵育并用于形成梯度支架。在微球中形成梯度的能力可能被证明是有用的，以实现更好地控制蛋白质从支架释放的动力学或产生梯度的固定化生长因子。
A critical element in the formation of scaffolds for tissue engineering is the introduction of concentration gradients of bioactive molecules. We explored the use of poly(ethylene glycol) (PEG) microspheres fabricated via a thermally induced phase separation to facilitate the creation of gradients in scaffolds. PEG microspheres were produced with different densities (buoyancies) and centrifuged to develop microsphere gradients. We previously found that the time to gelation following phase separation controlled the size of microspheres in the de-swollen state, while crosslink density affected swelling following buffer exchange into PBS. The principle factors used here to control microsphere densities were the temperature at which the PEG solutions were reacted following phase separation in aqueous sodium sulfate solutions and the length of the incubation period above the ‘cloud point’. Using different temperatures and incubation times, microspheres were formed that self-assembled into gradients upon centrifugation. The gradients were produced with sharp interfaces or gradual transitions, with up to five tiers of different microsphere types. For proof-of-concept, concentration gradients of covalently immobilized proteins were also assembled. PEG microspheres containing heparin were also fabricated. PEG-heparin microspheres were incubated with fluorescently labeled protamine and used to form gradient scaffolds. The ability to form gradients in microspheres may prove to be useful to achieve better control over the kinetics of protein release from scaffolds or to generate gradients of immobilized growth factors.
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DOI：
10.1073/pnas.0801866105
发表时间：
2008-07-15
影响因子：
11.1
作者：
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通讯作者：
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影响因子：
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作者：
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影响因子：
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作者：
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通讯作者：
Seliktar, D
影响因子：
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作者：
Moore, K;Macsween, M;Shoichet, M
通讯作者：
Shoichet, M