Pickering high internal phase emulsion templated poly(ɛ-caprolactone) scaffolds functionalized using type 1 collagen for enhanced bioactivity

Abstract

Overcoming the limitations associated with autologous and allogeneic grafts to treat refractory bone defects, bone regeneration scaffolds with tuneable physicochemical and biological activity have emerged as a promising alternative. In this direction, poly(ɛ-caprolactone) (PCL) based Pickering high internal phase emulsion (HIPE) templated scaffolds are widely studied.However, the inherent hydrophobicity and lack of biological activity severely restrict their applicability at the implant site. Addressing these concerns, we have developed Pickering HIPE templated PCL scaffolds using hydroxyethyl cellulose (HEC) as a functional macroinitiator for in-situ polymerization of Pickering HIPE followed by functionalization of the scaffolds with type 1 collagen. For this, Pickering HIPE were prepared by stabilizing ɛ-caprolactone (CL) and HEC solutions using hydrophobically modified silica nanoparticles (mSiNP) as Pickering stabilizers. The resulting scaffolds demonstrated excellent physicochemical characteristics with enhanced hydrophilicity and mechanical properties due to the presence of HEC. The unreacted functional sites were then utilized for collagen immobilization using a combination of Malaprade oxidation and Schiff base chemistry. EDX elemental mapping and type 1 collagen antibody staining confirmed the uniform presence of collagen throughout the surface of the scaffold. Finally, while all the scaffolds demonstrated excellent cytocompatibility, a significant increase in the metabolic activity was observed for collagen functionalized scaffolds which was attributed to its bioactive motifs that are recognized by cell binding integrins, thereby enhancing cell-material interaction leading to higher cellular adhesion and proliferation. Furthermore, a well-spread morphology of cells was observed on day 3 over the surface of collagen functionalized scaffold completely covering its porous architecture.