Calcium phosphate mineralization beneath monolayers of poly(n-butylacrylate)–block–poly(acrylic acid) block copolymers

Abstract

Amphiphilic poly(acrylic acid)-block-poly(n-butylacrylate) block copolymer films at the air-water interface have been mineralized with calcium phosphate. The polymers form stable monolayers at the free surface. Their stability is virtually independent of ion strength or pH changes in the subphase. The outcome of calcium phosphate crystallization depends on the calcium and phosphate concentrations, the stirring rate of the subphase, and the subphase pH. At low calcium and phosphate concentrations (2 mM), uniform polymer-calcium phosphate hybrid films form. Higher calcium and phosphate concentrations yield less ordered films, which often contain large blocks of material beneath the polymer monolayer. Occasionally, also filaments similar to samples described by Peytcheva et al. (Colloid Polym. Sci., 2002, 280, 218) are observed. Films mineralized at pH values below ca. 6 contain particles that are a few nanometers apart and the resulting films retain some flexibility. Films grown above pH 6 have a higher degree of mineralization. They are stiff and tend to break upon mechanical stress. Overall, the paper illustrates that low calcium phosphate supersaturation in the subphase and a well-defined (but not crystalline) interface are crucial for controlling calcium phosphate mineralization. As a result, the current study could serve as a model for biological mineralization which is more closely related to Nature than films made from e.g. detergents or low molecular mass compounds.

Poly(ethylene oxide)-based block copolymers with very high molecular weights for biomimetic calcium phosphate mineralization

“…[43][44][45] To a large extent, this is due the well-known biopassivation abilities of PEO 46 and the strong interaction of poly(electrolyte)s with inorganic ions [47][48][49][50] and surfaces. 47,48,[51][52][53] The combination of highly charged remineralizition-enhancing 48,49,[54][55][56][57][58][59][60][61][62] or dissolution-limiting 63,64 polymer segments with the biopassivation of PEO is thus a viable strategy towards multifunctional polymers providing both anti-biolm and remineralization-enhancing behavior in one single system.…”

The Biomimetic Mineralization Closer to a Real Biomineralization

“…8b . It is remarkable that an interesting phenomenon in the recent publication, Casse et al (Casse, et al, 2008) has found that even a rather flexible matrix like the block copolymers film at the vapor-liquid interface not only leads to uniform particles with identical particle sizes, but also can act as a tool for the 2D arrangement of the resulting particles in a nearcrystalline order in a distorted hexagonal lattice. Regulating mineralization on the atomic (crystal phase) and the nanoscopic (particle size and shape) scale in the reported work is often encountered in the case that inorganic crystals are mineralized under organic matrix templates.…”

Usage of polymer brushes as substrates of bone cells

“…Moreover, the block copolymer film at the air/water interface also acts as a tool for the 2D arrangement of the resulting particles in a nearcrystalline order [46]. The Wentrup-Byrne group has demonstrated that the amount of phosphate groups in the matrix polymers [poly(monoacryloxyethyl phosphate) and poly(2-(methacryloyloxy)-ethyl phosphate)] had great impact on the calcium phosphate crystallization.…”