生物材料中的分子自组装

Self-assembly provides a powerful paradigm for creating biomaterials that mimic the hierarchical complexity of biological tissues. The process is thermodynamically driven, seeking a minimum Gibbs free energy state. The design begins with molecular building blocks, often amphiphilic molecules (containing both hydrophilic and hydrophobic parts) such as block copolymers or peptide amphiphiles (PAs). When placed in an aqueous environment above a critical concentration, these molecules arrange themselves to minimize the unfavorable contact between their hydrophobic segments and water. This can lead to various nanostructures, including spherical micelles, cylindrical nanofibers, or planar bilayers, with the final morphology dictated by molecular geometry and packing parameters. A key advantage is the ability to encode biological function directly into the building blocks. For example, a PA can be designed with a peptide sequence containing the RGD motif, a well-known cell adhesion ligand. Upon self-assembly into nanofibers, this motif is displayed on the fiber surface, creating a scaffold that actively promotes cell attachment. These systems are often dynamic and responsive. A change in pH, temperature, or ionic strength can trigger a structural transition, allowing for the creation of ‘smart’ materials. For instance, a self-assembling peptide solution can be designed to be liquid for easy injection but form a solid 水凝胶 scaffold at body temperature, entrapping cells and drugs at a target site for regenerative medicine applications.