Cholesteryl-(L-lactic acid)n building blocks for self-assembling biomaterials

TThe synthesis and properties of a novel set of building blocks for the preparation of self-assembling biomaterials are described. These molecules consist of a relatively short oligo(L-lactic acid)n segment (n̄ = 10-40) that is substituted with a cholesterol moiety as an end group and in some cases has a second biofunctional substituent at its other terminus. The cholesterol moiety not only serves to induce liquid crystalline properties and drive the self-assembly of these oligomers, but also is expected to have an effect on the interaction of cells with these materials. The cholesteryl-(L-lactic acid)n̄ (CLAn̄) oligomers form thermotropic liquid crystals and self-assemble into lamellar structures consisting of interdigitated bilayers. In addition, the CLAn̄ oligomers can be homogeneously blended with poly(L-lactic acid), thereby offering the possibility to improve the cell interaction properties of this common surgical biomaterial. Furthermore, the secondary alcohol terminus of the CLAn̄ oligomers allows the opportunity to introduce additional bioactive substituents such as cholesterol, indomethacin (an antiinflammatory drug), and pyrene and rhodamine B (which can act as fluorescent labels for bioimaging purposes) and various α-amino acids. These biofunctional CLAn̄ oligomers can also be homogeneously mixed with the unsubstituted CLAn̄ oligomers and thus could enable a further noncovalent functionalization of self-assembling biomaterials.