The gelation kinetics of four β-hairpin oligopeptides that have been designed to exhibit responsive behavior to changes in environmental conditions, such as pH, ionic strength and temperature, are characterized using multiple particle tracking microrheology and circular dichroism (CD) spectroscopy. The peptides, predominantly an alternating sequence of valine and lysine residues, differ by a point substitution of a single amino acid near a type II'β-turn sequence. The rate of gelation becomes faster for point substitutions which reduce the total charge of the peptide.
View Article and Find Full Text PDFThe viscoelastic properties of physical and chemical polymer gels are characterized through the liquid-solid transition using particle tracking microrheology. Measurements of the probe particle mean-squared displacement are shifted as the extent of gelation increases to generate master curves. From the shift factors, we determine the gel point and critical scaling exponents.
View Article and Find Full Text PDFOrganic monolayer protected Cu2S nanorods, 4 nm in diameter and 12 nm long, were synthesized using a novel solventless synthetic approach. Thermolytic degradation of a copper thiolate precursor at temperatures ranging from 140 to 200 degrees C produces Cu2S nanorods. Higher temperatures promote isotropic growth of spherical nanocrystals.
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