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Title: Effect of otoconial proteins fetuin A, osteopontin, and otoconin 90 on the nucleation and growth of calcite

Here, 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 proteinsmore » 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.« less
 [1] ;  [2] ;  [3] ;  [4] ;  [2] ;  [2]
  1. Pacific Northwest National Lab. (PNNL), Richland, WA (United States); The George Washington Univ., Washington, D.C. (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  2. Washington Univ., St. Louis, MO (United States)
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
  4. The George Washington Univ., Washington, D.C. (United States)
Publication Date:
Grant/Contract Number:
AC05-76RL01830; RO1 DC011614
Accepted Manuscript
Journal Name:
Crystal Growth and Design
Additional Journal Information:
Journal Volume: 15; Journal Issue: 1; Journal ID: ISSN 1528-7483
American Chemical Society
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
OSTI Identifier: