Improving Hydrophobicity of Collagen with Silica Nanoparticles: Probing a Noncovalent Approach

Collagen-based materials have a widerange of applications in woundcare, tendon repair, cartilage repair, etc. Improving certain propertiessuch as hydrophobicity can diversify the application areas. In thiswork, we investigated the noncovalent interactions of suitably functionalizedsilica nanoparticles with collagen for the possibility of improvinghydrophobicity. Functionalization on silica nanoparticles was achievedvia Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) or "click"reaction using surface grafting methods. Furthermore, we synthesizedtwo different silica nanoparticles (SiNPs) functionalized with thefluorine-containing substrate or only with an aryl moiety (silica-g-4EMB and silica-g-ETFMB) for comparison.The functionalized SiNPs immobilized along with the model system trans-4-hydroxy-l-proline (HPA) (usually present in abundant quantities in collagen)have been probed using nuclear magnetic resonance (NMR) spin relaxationto appreciate the influence of SiNPs on HPA. Furthermore, we effectivelyutilized a saturated transfer difference (STD) NMR experiment to measurethe interaction parameters between judiciously functionalized silicananoparticles and substrates of interest. In essence, such a detailedstudy on noncovalent interactions employing an arsenal of experimentalapproaches facilitated the immobilization of suitably functionalizedsilica nanoparticles to collagen and leather (where collagen is amajor constituent), leading to improvements in hydrophobicity.