Title: In-situ ellipsometric study of calcium phosphate biomineralisation on organic thin films

Authors: Rayomand Shahlori; Geoffrey I.N. Waterhouse; Andrew R.J. Nelson; Duncan J. McGillivray

Addresses: School of Chemical Sciences, The University of Auckland, Private Bag 92019, Auckland, New Zealand; The MacDiarmid Institute for Advanced Materials and Nanotechnology, P.O. Box 600, Wellington, 6140, New Zealand ' School of Chemical Sciences, The University of Auckland, Private Bag 92019, Auckland, New Zealand; The MacDiarmid Institute for Advanced Materials and Nanotechnology, P.O. Box 600, Wellington, 6140, New Zealand ' Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia ' School of Chemical Sciences, The University of Auckland, Private Bag 92019, Auckland, New Zealand; The MacDiarmid Institute for Advanced Materials and Nanotechnology, P.O. Box 600, Wellington, 6140, New Zealand

Abstract: In this study, in-situ ellipsometry and scanning electron microscopy (SEM) were used to follow the growth kinetics of calcium phosphate (CaP) films on zein and hexadecanoic acid (HDA) layers self-assembled at the air-liquid interface. The duration of the mineral film induction period was heavily dependent on the organic template used, presence or absence of Mg2+, solution pH and concentration. In a standard simulated body fluid (SBF) solution at 20°C and pH 7.4, CaP film growth occurred after an induction period of 40 min for HDA and 100 min for zein. In the absence of Mg2+ the mineralisation induction period was reduced, for only the zein protein, to 50 min. At pH 6, HDA and zein-induced CaP films started forming after 100 min and 180 min, respectively. No induction period was observed when the SBF concentration was doubled, with immediate CaP growth observed for both HDA and zein. This study shows the effect of biomineralisation conditions on the growth of CaP with the organic template playing an important role. Knowledge of the factors that influence mineral growth processes is of importance in areas of biomineralisation and controlled crystal growth.

Keywords: biomineralisation; zein protein; calcium phosphate; organic template; air-water interface; ellipsometry; organic thin films; growth kinetics; hexadecanoic acid; HDA; mineral growth.

DOI: 10.1504/IJNT.2017.082457

International Journal of Nanotechnology, 2017 Vol.14 No.1/2/3/4/5/6, pp.375 - 384

Published online: 21 Feb 2017 *

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