@article {15125,
	title = {In-Vitro Bioactivity of Starch Thermoplastic/Hydroxylapatite Composite Biomaterials: An In-Situ Study Using Atomic Force Microscopy},
	journal = {Biomaterials},
	volume = {24},
	year = {2003},
	month = {2003-02-16 00:00:00},
	pages = {579-585},
	publisher = {Elsevier},
	abstract = {<p><span>The in vitro bioactivity of a composite composed by a biodegradable starch-based polymeric matrix and hydroxyapatite fillers was investigated, in situ, as a function of immersion time in a simulated body fluid (SBF) using atomic force microscopy (AFM). The surface roughness of the composite started to increase after the initial 8\&nbsp;h because of both the degradation of the polymer matrix and the nucleation of calcium phosphate. After 24\&nbsp;h of immersion the surface of the composite was fully covered with calcium phosphate nuclei with diameters around 126\&nbsp;nm. As the immersion time increased, the nuclei increased both in number and size, and coalesced leading to the formation of a dense and uniform calcium phosphate layer on the surface of the composite only after 126\&nbsp;h of SBF immersion. The results of in situ AFM observation agreed with those of standard in vitro bioactivity tests in combination with scanning electron microscopy observations. Thin-film X-ray diffraction demonstrated that the ratio of apatite to the polymer matrix was higher within the surface layer (40\&nbsp;μm deep from the surface) than that in the bulk after the immersion for 7 days. The water-uptake capability of the polymer contributes to the nucleation and growth of the calcium phosphate layer. These results suggest the great potential of the composite for a range of temporary applications in which bone-bonding ability is a desired property.</span></p>},
	keywords = {Atomic force microscope, bioactivity, Calcium phosphates, composites, Degradable polymer, hydroxyapatite},
	doi = {10.1016/S0142-9612(02)00371-X},
	url = {http://www.sciencedirect.com/science/journal/01429612/24/4},
	author = {Leonor, I. B. and Ito, A. and Onuma, K. and Kanzaki, N. and Reis, R. L.}
}
