Nanochemistry and biotechnology

Analysis of the effect of AlCl3 and FeCl3 concentration in BSA solutions on the parameters of film textures upon reaching the isoelectric point
D. Glibitskiy1, O. Gorobchenko2, O. Nikolov2, T. Cheipesh3,
T. Dzhimieva3,4, I. Zaitseva4,5, A. Zibarov6, A. Roshal6,
M. Semenov1, A. Khrebtova1, G. Glibitskiy1
1 Department of biological physics, O.Ya. Usikov Institute for Radiophysics and Electronics, National Academy of Sciences of Ukraine, Kharkiv, 61085, Ukraine.
E-mail: dima.glib@gmail.com
2 Department of molecular and medical biophysics, School of radiophysics, biomedical electronics and computer systems, V.N. Karazin Kharkiv National University, Kharkiv, 61022, Ukraine.
3 Chemical faculty, V.N. Karazin Kharkiv National University, Kharkiv, 61022, Ukraine.
4 V.N. Karazin Kharkiv National University, Kharkiv, 61022, Ukraine.
5 O.M. Beketov National University of Urban Economy, Kharkiv, 61002, Ukraine.
6 Institute for Chemistry, V.N. Karazin Kharkiv National University, Kharkiv, 61022, Ukraine.

A method for assessing the effect of physicochemical factors on biopolymers by analyzing textures on films resulting from their dried solutions was previously presented. The main parameters for describing textures in this method are the specific length Lspec and the number of segments of zigzag patterns Nsegm.
In the present work, analysis of the influence of different concentrations of AlCl3 and FeCl3 (from 0.1 to 0.4 mmol/l) on the change in texture parameters has been performed. It was found that with pH values going from 3.58 to 3.38, the decrease in Nsegm and Lspec for AlCl3 ranges from 5000 to 1800 and from 4.2 to 2.6, respectively. In FeCl3 solutions, the decrease of pH from 2.8 to 2.46 results in decreasing Nsegm and Lspec from 6400 to 0 and from 6 to 0, respectively.
The decrease in Nsegm and Lspec correlates with the onset of BSA precipitation in solutions at pH < 3.7 (AlCl3) and pH < 3 (FeCl3), which may be due to the reentrant condensation in solutions due to a significant decrease in the absolute value of the protein surface potential.
Thus, it can be concluded that the dominant factor in the change in Nsegm and Lspec is the change in the concentration of Al+3 and Fe+3 ions.