The activity of biological components depends both on the nature of the chemical signal and on its density and spatial organization. Engineering materials with functional domains (e.g. anisotropic particles, patchy or multi-compartment particles) is of great interest due to their ability to mimic number of analogues in nature. Here we describe a new method to create bi-functional patchy silica particles (SiNP).
Several alkoxysilane precursors were designed and synthesized bearing (i) a self-assembling group (e.g. anthracene) protecting (ii) a function of interest for bioconjugation (amine) and (iii) an alkoxysilane moiety for the transfer of the assemblies at the surface of the SiNP by sol-gel chemistry. Alkoxysilane self-assemblies were analyzed in different solvents by analytical and imaging techniques (DLS, Spectroscopy, (cryo)TEM). This method enabled us to create size-controlled patches at the surface of the particle. Upon deprotection of the self-assembling groups, amines are revealed for the grafting of bioactive ligands. The density of those ligands was tuned by modifying the size of the patches by influencing the alkoxysilane self-assemblies.
A second molecule of interest can be grafted between the patches, simultaneously or in a two-steps synthesis, in order to create bi-functional particles. In this work, the SiNP were used as a multifunctional platform allowing the co-grafting of biomolecules of interest for axonal out-growth, namely laminin-binding domains that are penta-peptide epitopes (IKVAV) and sulfonate groups (SO3- obtained from the grafting of commercial alkoxysilane) that have been shown to interact with positively charged collagen.
The underlying motivation for this multi-component approach is to control the collagen scaffold bioactivity by adjusting the laminin epitope concentration via its chemical confinement, while maintaining the favorable mechanical and cell adhesion properties of collagen.
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