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

The 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) over bar) segment ((n) over bar = 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)((n) over bar) (CLA((n) over bar)) oligomers form thermotropic liquid crystals and self-assemble into lamellar structures consisting of interdigitated bilayers. In addition, the CLA((n) over bar) 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 CLA((n) over bar) 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 alpha-amino acids. These biofunctional CLA((n) over bar) oligomers can also be homogeneously mixed with the unsubstituted CLA((n) over bar) oligomers and thus could enable a further noncovalent functionalization of self-assembling biomaterials.