K. Moreland - Effect of Otoconial Proteins Fetuin A, Osteopontin, and Otoconin 90 on the Nucleation and Growth of Calcite.

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  Publication Details (including relevant citation   information):

  Crystal Growth & Design

  Vol. 15, No. 1, pg. 129-136 (2015)

  ISSN: 1528-7483

  DOI: 10.1021/cg501001r


  We investigated the roles of three proteins associated with the   formation of otoconia including fetuin A, osteopontin (OPN), and   otoconin 90 (OC90). In situ atomic force microscopy (AFM) studies   of the effects of these proteins on the growth of atomic steps on   calcite surfaces were performed to obtain insight into their   effects on the growth kinetics. We also used scanning electron   microscopy to examine the effects of these proteins on crystal   morphology. All three proteins were found to be potent inhibitors   of calcite growth, although fetuin A promoted growth at   concentrations below about 40 nM and only became an inhibitor at   higher concentrations. We then used in situ optical microscopy to   observe calcite nucleation on films of these proteins adsorbed   onto mica surfaces. By measuring the calcite nucleation rate as a   function of supersaturation, the value of the interfacial energy   that controls the free energy barrier to heterogeneous nucleation   was determined for each protein. OPN and OC90 films led to   significantly reduced interfacial energies as compared to the   value for homogeneous calcite nucleation in bulk solution. The   value for fetuin A was equal to that for bulk solution within   experimental error. Zeta potential measurements showed all of the   proteins possessed negative surface charge and varied in   magnitude according to sequence fetuin A > OC90 > OPN. In   addition, the interfacial energies exhibited an inverse scaling   with the zeta potential. In analogy to previous measurements on   polysaccharide films, this scaling indicates the differences   between the proteins arise from the effect of protein surface   charge on the solution?substrate interfacial energy.

  Mina Hong

  Address (URL): http://pubs.acs.org/doi/abs/10.1021/cg501001r