Pickering high internal phase emulsion templated poly(ε-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 have emerged as a promising alternative. In this direction, poly(ε-caprolactone) (PCL) based Pickering high internal phase emulsion (HIPE) templated scaffolds are widely studied. However, the inherent hydrophobicity and lack of biological activity of these scaffolds severely restrict their applicability at the implant site. Addressing this, 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 with type 1 collagen. Pickering HIPE was prepared by stabilizing ε-caprolactone (CL) and HEC solutions using hydrophobically modified silica nanoparticles (mSiNP) as Pickering stabilizers. The resulting scaffolds demonstrated a decrease in contact angle from ∼90° to ∼66° and increase in compressional stress from 22k Pa to 64.6k Pa due to the presence of HEC. The unreacted functional sites were 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 3 times increase in the metabolic activity was observed at day 7 for the collagen functionalized scaffolds, which was attributed to the bioactive motifs present over the surface of scaffolds. Furthermore, a well-spread morphology of cells was observed on day 3 over the surface of the collagen functionalized scaffold completely covering its porous architecture.