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DEAE-dextran hydrochloride is a positively charged biocompatible polyelectrolyte. Its behaviour in aqueous solutions - the changes in its colloidal characteristics and resulting conformation changes - were investigated using a combination of light scattering, densitometry and ultrasound spectrometry. The results indicated the formation of a voluminous, hydrated and coiled conformation of chains having average particle sizes in the range of units of microns at low ionic strength. This phenomenon was supported by an increase in DEAE-dextran hydrochloride concentration in the solution. The increase in ionic strength caused the shielding of DEAE-dextran hydrochloride charges on its chain, resulting in the destabilization of the conformation arrangement of the polyelectrolyte and the formation of denser, more compact and stiffer structures having smaller particle sizes. The proposed model of DEAE-dextran hydrochloride density in the studied environments (distilled water, NaCl solutions) showed the possibility of using a single equation model to calculate the overall density of the system., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

The aim of this paper is the rheological characterization of the concentrated, gel-like phase, which arises from mixed solutions of sodium hyaluronate and oppositely charged surfactant above its critical micellar concentration. The effects of hyaluronan molecular weight (from 300 to 2kDa) and the concentration of initial solutions (0.5 and 2% for hyaluronan, 50 or 200mM for surfactant) were investigated. All systems demonstrated viscoelastic properties which can be modified over a broad range of several decades of both storage and loss moduli by the hyaluronan molecular weight and initial concentrations. The characteristic relaxation time increased with the molecular weight of hyaluronan at constant initial composition. The effect of molecular weight on characteristic moduli was dependent on initial composition - the modulus increased with molecular weight for systems with 50mM of the surfactant and decreased for the other systems. Whereas no correlation was found between gel rheological properties and the surfactant:hyaluronan charge ratio, the properties were sensitive to structural features of surfactant molecules, particularly when low and moderate hyaluronan molecular weight was used., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

The degradation of hyaluronan (HA) of different molecular weights (Mw 14.3, 267.2 and 1160.6 kDa, measured for fresh solutions, before degradation) was studied in aqueous solutions by SEC-MALLS determination of molecular mass, polydispersity and conformation parameters. The solutions were stored either at laboratory or refrigerator temperatures for two months. After this period the weight average molecular weight decreased by 90% for 14.3 kDa, 95% for 267.2 kDa and 71% for 1160.6 kDa hyaluronan (room temperature) or 5.6% for 14.3 kDa, 6.2% for 267.2 kDa and 7.7% for 1160.6 kDa hyaluronan (refrigerator temperature). The hyaluronan aqueous solutions studied did not contain sodium azide or other protectants against microorganisms, because the aim of our study was to assess the degradation in solutions to be used in medicine or cosmetics (without any compounds that are poisonous or toxic for the human body). The solvent used to prepare the samples was pure water. The polydispersity of all the samples remained unaltered during the entire degradation at both temperatures. This indicates a non-random mechanism of degradation., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

The fast deprotonation of 1-naphthol was studied in aqueous solution and in polymer-cetyltrimethylammonium bromide (CTAB) mixtures using picosecond fluorescence spectroscopy to study the influence of hyaluronan hydration in polymer-surfactant interactions. The aqueous micelle solution showed the expected change of proton transfer rate around the reported critical micelle concentration (∼1 mM). The proton transfer rate dependence on CTAB concentration in the hyaluronan-CTAB and polystyrenesulfonate-CTAB systems differed significantly from that in the aqueous micelle solution. The dynamic study of excited state proton transfer (ESPT) revealed the significant influence of hyaluronan hydration in CTAB micelles. When hyaluronan-CTAB aggregates were formed at the CTAB concentration of 0.5mM, a tenfold decrease in the rate of deprotonation was observed when compared to polystyrenesulfonate-CTAB aggregates due to hyaluronan hydration. In 2mM CTAB-hyaluronan aggregates, the rate of deprotonation was found to be almost two times faster than in the 2mM CTAB or polystyrenesulfonate-CTAB system. Furthermore, the study of excited-state proton transfer of 1-naphthol confirmed that hyaluronan hydration layer penetrates into the micelle and changes the emission characteristics of 1-naphthol., (Copyright © 2015 Elsevier Ltd. All rights reserved.)