Highly active porous scaffolds of collagen and hyaluronic acid prepared by suppression of polyion complex formation

Abstract

Collagen–hyaluronic acid scaffolds with high bioactivity, good mechanical properties and homogeneous pore structures are desirable for their applications in tissue engineering. However, under aqueous conditions collagen and hyaluronic acid form polyion complexes (PIC), which results in heterogeneous structures and poor mechanical properties of the scaffolds. In this study, we used low molecular weight salts to suppress PIC formation in collagen–hyaluronic acid suspensions during scaffold preparation. The suppression of PIC formation was studied by using turbidimetry, viscosity measurement and infrared analysis. The effects of suppression of PIC formation on the morphology and mechanical properties of the scaffolds were examined using scanning electron microscopy and compression tests. PIC formation was found to be dependent on the ionic strength of the suspension. The secondary structure of collagen was partially altered by its strong electrostatic interactions with hyaluronic acid. The suppression of PIC formation resulted in collagen–hyaluronic acid scaffolds with homogeneous pore structures and remarkably enhanced mechanical properties. Collagen–hyaluronic acid scaffolds prepared under suppression of PIC formation promoted proliferation of fibroblasts and upregulated the expression of genes encoding EGF, VEGF and IGF-1. Using low molecular weight salts to suppress PIC formation could aid in the design of collagen–glycosaminoglycan scaffolds for tissue engineering.