화학공학소재연구정보센터
Applied Surface Science, Vol.360, 86-97, 2016
Bifunctional coating based on carboxymethyl chitosan with stable conjugated alkaline phosphatase for inhibiting bacterial adhesion and promoting osteogenic differentiation on titanium
In this work, alkaline phosphatase (ALP) was covalently immobilized on carboxymethyl chitosan ( CMCS)coated polydopamine (PDA)-functionalized Ti to achieve a bifunctional surface. Our results showed 89% reduction in Staphylococcus epidermidis adhesion on this surface compared to that on pristine Ti. The ALPmodified Ti supported cell proliferation, and significantly enhanced cellular ALP activity and calcium deposition of osteoblasts, human mesenchymal stem cells (hMSCs) and human adipose-derived stem cells (hADSCs). The extent of enhancement in the functions of these cells is dependent on the surface density of immobilized ALP. The substrate prepared using an ALP solution of 50 vg/cm2 resulted in 44%, 54% and 129% increase in calcium deposited by osteoblasts, hMSCs and hADSCs, respectively, compared to those cultured on pristine Ti. The ALP-modified substrates also promoted the osteogenic differentiation of hMSCs and hADSCs by up-regulating gene expressions of runt-related transcription factor 2 (RUNX2), osterix ( OSX), and osteocalcin ( OC) in the two types of stem cells. The surface-immobilized ALP was stable after being subjected to 1 h immersion in 70% ethanol and autoclaving at 121 C for 20 min. However, the enzymatic bioactivity of the surface-immobilized ALP was reduced by about 50% after these substrates were immersed in phosphate buffered saline (PBS) or PBS containing lysozyme for 14 days. (C) 2015 Elsevier B.V. All rights reserved.