Zeta-potential and Particle Size Analysis of Human Amelogenins

Abstract

The developing enamel matrix is a highly dynamic system mainly composed of the full-length amelogenin and its proteolytic cleavage products. In this study, size, zeta-potential, and the isoelectric points of nanoparticles of the recombinant full-length human amelogenin (rH174) and two proteolytic products (rH163 and rH146) were analyzed by dynamic light-scattering and electrokinetic measurements. We tested the hypothesis that zeta-potential may be used as a control parameter in directing the self-assembly of amelogenins. Extensive aggregation of amelogenin molecules with the particle size reaching about one micron occurred at a mildly acidic to neutral pH, and coincided with the red shift of the internal fluorescence. Zeta-potential was between ± 15 mV in the same pH range, indicating that amelogenin aggregation occurred when surface potentials were minimal. This suggests that electrostatic interactions may be another crucial factor, aside from hydrophobic interaction, in the aggregation and hierarchical assembly of spherical particles of amelogenins into supramolecular structures of a higher order.

Dissecting Amelogenin Protein Nanospheres

“…The most striking observation from steady state intrinsic tryptophan fluorescence was a sharp blue shift of 7-8 nm in the emission maximum that occurred between pH 5.8 and 6.1 and was concomitant with visible aggregation. A similar observation has been made previously in the case of human amelogenin (26), although the narrow range in which the shift occurred was not noted. Prior to the large blue shift at pH 5.8, we observed a smaller gradual blue shift of 3 nm between pH 3.4 and 5.8 ( Fig.…”

“…Accordingly, the midpoint of the large shift in fluorescence occurs around pH 6.1, which is close to the pK a value of histidine and is concomitant with visible aggregation of the protein. -Potential studies on recombinant human amelogenin have shown that there is no charge on the protein at around pH 6.8 and that a small positive charge on the protein cannot cause dispersion as effectively as a small negative charge (26).…”

Optimization of process parameters by Taguchi robust design method for the development of nano‐crystals of sirolimus using sonication based crystallization

“…Cao et al [33] have found that addition of surfactant enhances negative zeta potential values and has a major role in the size of the crystal formation. Uskokovic et al [34] found that value of zeta potential and particle size are highly dependent on the pH of a solution. Further they [34] envisaged that as pH of a medium increases, value of zeta potential decreases and causes aggregation and destabilization of suspension.…”

“…Scientific analysis Apart from statistical analysis, the use of scientific theory will help to understand the correlation of particle size and its surface charges. Researchers [26][27][28][29][30][31][32][33][34] found that quantity and quality of surfactant have major role in the surface charge of the crystals or particles formed and the surface charge controls the size of the crystals or particles. From figure 1, tables 1 and 3, it can be said that at higher amount of surfactant (3.1 mL), the S/N ratio is minimum (-275.67) which indicates that surfactant has an impact on the particle size formation.…”

Cryogenic Transmission Electron Microscopy Study of Amelogenin Self-Assembly at Different pH

“…In vitro, amelogenin has been shown to self-assemble, forming nanospheres of 15-20 nm in diameter similar to those formed in vivo Moradian-Oldak et al, 1994;Fincham et al, 1995]. These nanospheres have been intensively characterized, for example, by dynamic light scattering (DLS) [Uskokovic et al, 2010;Fincham et al, 1998;Wiedemann-Bidlack et al, 2007], atomic force microscopy [Moradian-Oldak et al, 2000], transmission electron microscope (TEM) [Du et al, 2005;Wiedemann-Bidlack et al, 2007], small angle X-ray scattering [Aichmayer et al, 2005], and nuclear magnetic resonance [Buchko et al, 2010;Delak et al, 2009].…”