A large mobility of hydrophilic molecules at the outmost layer controls the protein adsorption and adhering behavior with the actin fiber orientation of human umbilical vein endothelial cells (HUVEC)

Polyrotaxane-based biointerfaces with dynamic biomaterial functions

The molecular mobility of cyclic molecules (e.g.α-cyclodextrins) threaded along a linear polymer chain (e.g. poly(ethylene glycol)) in polyrotaxanes is a unique feature for biomaterials with dynamic functionality. Surfaces with molecular mobility can be obtained by introducing polyrotaxanes. The molecular mobility of polyrotaxane-based surfaces can be modulated by changing the number of threaded cyclic molecules and modifying their functional groups. Biological ligands modified with α-cyclodextrins exhibit increased multivalent interactions with their receptors due to the molecular mobility of the latter. Furthermore, polyrotaxane-based surfaces not only improve the initial response of cells via multivalent interactions, but also affect cytoskeleton formation and the inherent quality of cells, including differentiation. Such polyrotaxane surfaces can emerge as new biointerfaces that can adapt to the dynamic biological nature.

Self-assembled phosphate-polyamine networks as biocompatible supramolecular platforms to modulate cell adhesion

The modulation of cell adhesion via biologically inspired materials plays a key role in the development of realistic platforms to envisage not only mechanistic descriptions of many physiological and pathological processes but also new biointerfacial designs compatible with the requirements of biomedical devices. In this work, we show that the cell adhesion and proliferation of three different cell lines can be easily manipulated by using a novel biologically inspired supramolecular coating generated via dip coating of the working substrates in an aqueous solution of polyallylamine in the presence of phosphate anions-a simple one-step modification procedure. Our results reveal that selective cell adhesion can be controlled by varying the deposition time of the coating. Cell proliferation experiments showed a cell type-dependent quasi-exponential growth demonstrating the nontoxic properties of the supramolecular platform. After reaching a certain surface coverage, the supramolecular films based on phosphate-polyamine networks displayed antiadhesive activity towards cells, irrespective of the cell type. However and most interestingly, these antiadherent substrates developed strong adhesive properties after thermal annealing at 37 °C for 3 days. These results were interpreted based on the changes in the coating hydrophilicity, topography and stiffness, with the latter being assessed by atomic force microscopy imaging and indentation experiments. The reported approach is simple, robust and flexible, and would offer opportunities for the development of tunable, biocompatible interfacial architectures to control cell attachment for various biomedical applications.

Dynamic polyrotaxane-coated surface for effective differentiation of mouse induced pluripotent stem cells into cardiomyocytes

Increasing molecular mobility of hydrated polyrotaxane (PRX)-coated surfaces was effective to promote the differentiation of mouse induced pluripotent stem cells (iPS cells) into cardiomyocytes.

Mobility of the Arg-Gly-Asp ligand on the outermost surface of biomaterials suppresses integrin-mediated mechanotransduction and subsequent cell functions

Mechanotransduction in the regulation of cellular responses has been previously studied using elastic hydrogels. Because cells interact only with the surface of biomaterials, we are focusing on the molecular mobility at the outermost surface of biomaterials. In this study, surfaces with the mobile Arg-Gly-Asp-Ser (RGDS) peptide have been constructed. Cell culture substrates were coated with ABA-type block copolymers composed of poly(2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate) segments (A) and a polyrotaxane (PRX) unit with RGDS bound to α-cyclodextrin (B). Adhesion, morphological changes and actin filament formation of human umbilical vein endothelial cells were reduced on the surfaces containing mobile PRX-RGDS in comparison to the immobile RGDS surfaces constructed from random copolymers with RGDS side groups (Prop-andom-RGDS). In the neurite outgrowth assay using rat adrenal pheochromocytoma cells (PC12), only ∼20% of adherent PC12 cells had neurites on PRX-RGDS surfaces, but more than 50% did on the Random-RGDS surface. The beating colony of dimethyl-sulfoxide-treated mouse embryonic carcinoma cells (P19CL6) were found 10 and 14 days after induction on PRX-RGDS and Random-RGDS surfaces, respectively. After 22 days, the beating colony disappeared on PRX-RGDS surfaces, but many colonies remained on Random-RGDS surfaces. These data suggest that the molecular mobility of the cell-binding ligand on the outermost surface of materials effectively suppresses the actin filament formation and differentiation of these functional cell lines, and may be used as a culture substrate for immature stem cells or progenitor cells.

Directing stem cell differentiation by changing the molecular mobility of supramolecular surfaces

Polymer surfaces with a wide range of hydrated surface mobility are developed by a simple deposition method with supramolecular block copolymers. The morphologies of adhering stem cells are greatly dependent on the surface mobility of polymers, and this induces significant changes in the cytoskeletal signaling pathway to direct the downstream stem cell differentiation.

Supramolecular flower micelle formation of polyrotaxane-containing triblock copolymers prepared from macro-chain transfer agents bearing molecular hooks

A precise synthesis of polyrotaxanes (PRX)-containing triblock copolymers was achieved using PRX macro-chain transfer agents with terminal hooks. Also, polymeric micelle formation of them in aqueous solution was investigated.