THE FMOC GROUP (9-FLUORENYLMETHOXYCARBONYL) AS AN INDUCER OF NANOSTRUCTURATION OF BIOACTIVE PEPTIDES AND THEIR ENCAPSULATION IN HYDROGELS

The development of bioactive matrices based on peptide nanostructures highlights the importance of these molecules for the formulation of new materials applicable in biomedicine. In the last years, the ability of peptides to form self-organized structures that mimic the extracellular matrix has been extensively explored, showing promise in tissue regeneration and controlled drug release systems. However, controlling the self-aggregation process is challenging, and many bioactive sequences do not exhibit such properties, preventing their use in nanostructured matrices. In this project, we analyzed how the introduction of the Fmoc group (9-fluorenylmethoxycarbonyl)  influences the aggregation of cell-penetrating peptides derived from BAX (Bcl-2-associated X protein) inhibitory sequences. Through this strategy,  short sequences that do not  exhibit self-organization capacity were shown to be capable of forming ordered arrangements. In addition, we found that the Fmoc group increased the ability of these peptides to inhibit the growth of MCF-7 and MDA-MB-231 tumor cells, while maintaining compatibility with non-tumor MCF10A cells. To increase the potential of these systems, we also investigated their compatibility with collagen matrices in the form of hydrogels. We observed that the Fmoc group increases this compatibility, suggesting potential use in biomaterial printing and controlled release. Moreover, structural analyses showed that  Fmoc-containing peptides display  lower critical aggregation concentrations (CAC) and propensity to form b-sheet enriched aggregates, as revealed by Thioflavin fluorescence assays. The nanoscale ordering of the peptides was investigated through a combination of  atomic and electron microscopy, as well as small-angle X-ray scattering,  revealing the presence of polymorphs that presumably are able to enhance cell membrane interactions. . In conclusion, the addition of Fmoc moieties to bioactive peptides was found to be a valid strategy to produce nanostructured materials with potential biomedical uses.