Composition and method for self-assembly and mineralization of peptide amphiphiles
The present invention is directed to a composition useful for making homogeneously mineralized self assembled peptide-amphiphile nanofibers and nanofiber gels. The composition is generally a solution comprised of a positively or negatively charged peptide-amphiphile and a like signed ion from the mineral. Mixing this solution with a second solution containing a dissolved counter-ion of the mineral and/or a second oppositely charged peptide amphiphile, results in the rapid self assembly of the peptide-amphiphiles into a nanofiber gel and templated mineralization of the ions. Templated mineralization of the initially dissolved mineral cations and anions in the mixture occurs with preferential orientation of the mineral crystals along the fiber surfaces within the nanofiber gel. One advantage of the present invention is that it results in homogenous growth of the mineral throughout the nanofiber gel. Another advantage of the present invention is that the nanofiber gel formation and mineralization reactions occur in a single mixing step and under substantially neutral or physiological pH conditions. These homogeneous nanostructured composite materials are useful for medical applications especially the regeneration of damaged bone in mammals. This invention is directed to the synthesis of peptide-amphiphiles with more than one amphiphilic moment and to supramolecular compositions comprised of such multi-dimensional peptide-amphiphiles. Supramolecular compositions can be formed by self assembly of multi-dimensional peptide-amphiphiles by mixing them with a solution comprising a monovalent cation.
1. A method for the mineralization of nanofibers, the method comprising:
preparing a first solution with at least one peptide amphiphile comprising a C 6 or greater hydrocarbon component at its N-terminus and a lyophilic peptide component;
preparing a second solution of a mineral salt; and
mixing said first and second solutions to self-assemble said peptide amphiphiles into nanofibers and a nanofiber gel,
wherein said mineralization occurs from initially dissolved mineral cations and anions along the nanofibers surfaces, wherein said nanofibers are fibrous cylindrical micelles.
2. The method claim 1 further comprising: aging the mixture of said first and second solutions to control the size and rate of growth of said minerals on the self-assembled peptide amphiphile nanofibers.
3. The method of claim 1 further comprising: adjusting the pH of one of the solutions prior to mixing them together.
4. The method of claim 1 , wherein said mineral cations and anions are selected from the group consisting of hydroxyapatite, fluoroapatite, calcium oxalate, calcite, tin hydrogen phosphate, iron oxides, iron hydroxides, iron oxyhydroxyoxides, titanium dioxide, and zinc oxide.
5. The method of claim 1 , wherein the peptide-amphiphile has a net negative charge.
6. The method of claim 4 , wherein the mineral is hydroxyapatite.