Department of Chemistry, University of Illinois, Urbana, IL 61801, USA.
Biomaterials. 2011 Apr;32(11):2695-703. doi: 10.1016/j.biomaterials.2010.12.038. Epub 2011 Jan 22.
A mineralized polymeric matrix has been extensively studied to understand biomineralization processes and to further regulate phenotypic functions of various cells involved in osteogenesis and physiological homeostasis. It has been often proposed that several matrix variables including charge density, hydrophobicity, and pore size play vital roles in modulating composition and morphology of minerals formed within a three dimensional (3D) matrix. However, the aspects have not yet been systematically examined because a tool enabling the independent control of the matrix variables is lacking. This study presents an advanced integrative strategy to control morphology and composition of biominerals with matrix properties, by using a hydrogel formulated to independently control charge density, hydrophobicity, and porosity. The hydrogel consists of poly(ethylene glycol) monomethacrylate (PEGmM), poly(propylene glycol) monomethacrylate (PPGmM), and methacrylic alginate (MA), so the charge density and hydrophobicity of the hydrogel can be separately controlled with mass fractions of MA and PPGmM. Also, hydrogels which present only nano-sized pores, termed nanoporous hydrogels, are lyophilized and rehydrated to prepare the hydrogels containing micro-sized pores, termed microporous hydrogels. We find that increasing the mass fractions of MA and PPGmM of the microporous hydrogel promotes the growth of apatite layers because of the increases in the charge density, hydrophobicity and pore size. In contrast, increasing mass fractions of MA and PPGmM of the nanoporous hydrogel enhances the formation of calcium carbonate minerals. The dependency of the mineralization on hydrogel variables is related to the change in supersaturation of mineral ions. Overall, the results of this study will be highly useful to better understand the interplay of matrix variables in biomineralization and to design a wide array of mineralized matrix potentially used in cell therapies and tissue engineering.
一个矿化聚合物基质已经被广泛研究以了解生物矿化过程，并进一步调节涉及成骨和生理稳态的各种细胞的表型功能。人们经常提出，包括电荷密度、疏水性和孔径在内的几种基质变量在调节在三维（3D）基质中形成的矿物质的组成和形态方面起着至关重要的作用。然而，由于缺乏能够独立控制基质变量的工具，这些方面尚未得到系统的研究。本研究提出了一种先进的综合策略，通过使用一种水凝胶来控制具有基质特性的生物矿物质的形态和组成，该水凝胶能够独立控制电荷密度、疏水性和孔隙率。该水凝胶由聚乙二醇单甲醚（PEGmM）、聚丙二醇单甲醚（PPGmM）和甲基丙烯酰化藻酸盐（MA）组成，因此水凝胶的电荷密度和疏水性可以分别通过 MA 和 PPGmM 的质量分数来控制。此外，只呈现纳米级孔径的水凝胶，称为纳米多孔水凝胶，通过冷冻干燥和再水合来制备只呈现微米级孔径的水凝胶，称为微孔多孔水凝胶。我们发现，增加微孔水凝胶中 MA 和 PPGmM 的质量分数会由于电荷密度、疏水性和孔径的增加而促进磷灰石层的生长。相比之下，增加纳米多孔水凝胶中 MA 和 PPGmM 的质量分数会增强碳酸钙矿物质的形成。矿化对水凝胶变量的依赖性与矿物质离子过饱和度的变化有关。总的来说，本研究的结果将非常有助于更好地理解基质变量在生物矿化中的相互作用，并设计出广泛应用于细胞治疗和组织工程的矿化基质。
