Study on the Effects of Type I Collagen Combined with Noncollagenous Proteins on Hydroxyapatite Formation in vitro using
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1238-UU03-05
Study on the Effects of Type I Collagen Combined with Noncollagenous Proteins on Hydroxyapatite Formation in vitro using SPM and GIXD Xiaolan Ba1, Elaine DiMasi2 and Miriam Rafailovich1 1 Department of Materials Science and Engineering, Stony Brook University, Stony Brook NY 11794 USA 2 National Synchrotron Light Source, Brookhaven National Laboratory, Upton NY 11973 USA
ABSTRACT The effects of the components of extracellular matrix on the bone formation and the kinetics of crystal growth of calcium phosphate have remained unknown. In this paper, we reported a method to investigate the role of Type I collagen and the interactions with other ECM proteins such as fibronectin and elastin during biomimic mineralization process in vitro. The early stage of mineralization was characterized by scanning probe microscopy (SPM) and shear modulation force microscopy (SMFM). The late stage of mineralization was investigated by synchrotron grazing incident x-ray diffraction (GIXD). The results demonstrate the cooperative interaction between type I collagen and noncollagenous proteins such as fibronectin or elastin could be essential for the biomineralization. INTRODUCTION Biomineralization refers to the formation of inorganic materials by living organisms, which is a widespread and important biological process [1]. It is a subject of constant scientific interest due to the broad potential application in materials and bio-medical engineering. Extracellular matrix (ECM) plays critical roles during biomineralization, not only providing a space to deposit mineral crystals but also conducting nucleation, crystal morphology and orientation of the biominerals with regard to hard tissue growth [2, 3]. Although numerous studies have been designed to elucidate the mechanisms that determine where, when, and how mineral crystals form in ECM of different hard tissues in vitro or in vivo [4-6], the fundamental mechanism of ECM-mediated biomineralization in hard tissues remains uncertain. In this paper, we successfully present an approach to mimic the ECM in vitro. Using a charged polymer substrate we show that the pure type I collagen and collagen binding with two noncollagenous proteins (NCPs), fibronectin and elastin, self assemble into a common fiber network. Our previous work has demonstrated that those two NCPs have different functions during biomineralization [7]. To improve the understanding of the interaction between organic molecules and biominerals during the initial stage of biomineralization, we demonstrate complementary surface sensitive techniques to study the process of biomimetic mineralization from the earliest stages. By exposing the fibers to calcium phosphate solution at physiological pH and ionic concentration, we are able to track the subtle changes of mechanical property of protein fibers by scanning probe microscopy (SPM) and shear modulation force microscopy (SMFM). Grazing incidence X-ray diffraction (GIXD) is used to determine crystalline property
of mineral. EXPERIMENT Surface preparation Polished
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