Rheological and spectral properties of aqueous solutions of phenylalanine

Abstract

Viscosity and spectral properties of individual aqueous solutions of phenylalanine in a wide range of concentrations is studied. The structures with hydrodynamic radii of 1 - 2 nm and 20 - 50 nm in the diluted solutions of phenylalanine with a concentration of less than 22 ± 2 mmol/L is revealed. A plateau is observed on the concentration dependence of the reduced viscosity in the region concentrations of phenylalanine of more than 22 ± 2 mmol/L, indicating the formation of stable configurations associates. It is established that in this region the formation of agglomerates with hydrodynamic radii of 90 -100 nm and 150 - 200 nm takes place using the method of photon correlation spectroscopy. The further growth of the reduced viscosity corresponds to an increase in the number of particles in the associative structure. The increase in the concentration of amino acid in the solution leads to a decrease in the content of structures with a hydrodynamic radius of 90 - 100 nm. There are larger agglomerates with a hydrodynamic radii of 150 - 200 nm, the maximum content of which corresponds to the extremum of the reduced viscosity. The sharp decrease in the values of the reduced viscosity is indicates the formation of a denser three-dimensional structure in the concentration range of phenylalanine greater than 0.055 mol/L. The compaction of amino acid associative structure leads to an increase in the content of particles with a hydrodynamic radii of 90 - 100 nm. A possible scheme of self-assembled structures in the phenylalanine - phenylalanine system is shown