Characterization of medical biopolymers by ultrasound spectroscopy

Pomocí ultrazvukové spektroskopie s vysokým rozlišením byly zkoumány vlastnosti roztoků hyaluronanu o různé molekulové hmotnosti v závislosti na koncentraci a teplotě roztoku. Dále byl zkoumán vliv iontové síly na vlastnosti roztoků pomocí rozpouštění hyaluronanu v 0,15 M vodném roztoku chloridu sodného. Pro vyhodnocení vlastností roztoků byly výsledky porovnávány s vodnými roztoky karagenanu. Bylo zjištěno, že hyaluronan se v roztocích chová stále stejně a nedochází u něho k žádným změnám, nezávisle na hmotnosti, teplotě či koncentraci.Using high resolution ultrasonic spectroscopy has been investigated hyaluron solutions of various molecules weights depending on their concentration and solution temperature. Furhermore, the influence of ionic strenght on the properties of solutions by dissolving hyaluronan in 0.15 M aqueous solution of sodium chloride. For comparison the properties of the hyaluronan solutions were compared with aqueous solutions of carrageenan. It was found that hyaluronan in solution behaves the same, regardless of the weight, temperature and concentration.

Study of interactions of hyaluronan-amino acids

Diplomová práce se zabývá studiem interakcí mezi polysacharidem hyaluronanem o různých molekulových hmotnostech s aminokyselinami argininem, lysinem, argininem hydrochloridem a 6-aminokapronovou kyselinou. Předpokládají se interakce mezi karboxylovými skupinami hyaluronanu a aminoskupinami aminokyselin. Interakce byly zkoumány pomocí technik ultrazvukové spektroskopie, DLS, měřením pH a vodivosti. Výsledky byly porovnávány s roztoky polystyren sulfonátu sodného. Pomocí ultrazvukové spektroskopie byla pozorována změna koncentračního inkrementu při titracích aminokyselin do vody a roztoků polymerů především u vysokých molekulových hmotností hyaluronanu a u NaPSS v kombinaci s 6AKK v koncentračním rozsahu přidané aminokyseliny 0–30 mM. Velikost této změny by mohla znamenat míru interakcí mezi polymery a aminokyselinami. Tato teorie ale nebyla potvrzena ostatními metodami. V případě měření pH a vodivosti roztoků byly interakce potvrzeny pouze pro nízkomolekulární hyaluronan a polystyren sulfonát interagující s argininem. U stanovování velikosti částic a měření zeta potenciálu pomocí DLS nebylo ze získaných výsledků možné stanovit jednoznačné závěry. Celkově se problematika interakce aminokyselin spolu s polyanionty ukázala nad očekávání komplexní a bude vhodné pozorování provedená v této práci dále rozšířit.The master´s thesis deals with the study of the interaction between the polysaccharide hyaluronan of diffrerent molecular weights with the amino acids arginine, lysine, arginine hydrochloride and 6-aminocaproic acid. They are expected interaction between carboxyl groups of hyaluronan and amino groups of amino acids. These interactions were investigated by using ultrasonic spectroscopy, DLS, measuring pH and conductivity. Obtained results were compared with sodium polystyrene sulfonate. With ultrasonic spectroscopy was observed a change of concentration inkrement for titration of amino acid to water or polymers solutions especially for high molecular weight hyaluronan and for NaPSS in combination with 6AKK in concentration range of added amino acid 0–30 mM. The size of this change could mean a degree of interaction between polymers and amino acids. This theory has not been confirmed by other methods. By pH and conductivity measurements interations between arginine and low molecular weight hyaluronan and NaPSS were only confirmed. There was no possibility to make unequivocal conclusions from determination of particle size and zeta potential by DLS. Overall, the issue of the interaction of amino acids with polyanions was proved above expectations complex and will be appropriate to further expand the observations made in this thesis.

Hyaluronan-amino acids interactions

The presented dissertation focuses on non-covalent interactions of hyaluronan of different molecular weights (9–1540 kDa) with basic (oligo)-amino acids (especially arginine) and the antimicrobial peptide cecropin B. High-resolution ultrasonic spectroscopy (HR-US), isothermal titration calorimetry (ITC) and potentiometric titration techniques were chosen to investigate the interactions. The thesis focuses on the characterization of interactions, especially with respect to the used molecular weight of interacting polymers and the ionic strength of the environment. Whether interactions occur or not was determined primarily by the length of the arginine oligomer chain. For monomeric amino acids, the interactions were investigated mainly by potentiometric titrations. Interactions were observable from arginine oligomers with eight monomer units. The molecular weight of hyaluronan mainly affected the intensity of the interactions. The transition between the individual conformations of hyaluronan (rod and random coil) was especially significant. Investigation of interactions was performed in water, in solutions with different concentrations of sodium chloride and in PBS. The sufficiently high ionic strength of the solution was able to suppress the interactions in water between the oligomers of arginine and hyaluronan. The basic antimicrobial peptide cecropin B has been shown to interact with hyaluronan in water but not in PBS. Based on these results, it was possible to conclude that the hyaluronan-cecropin B system would be particularly suitable for topical applications

Hyaluronan-Arginine Interactions-An Ultrasound and ITC Study

High-resolution ultrasound spectroscopy and isothermal titration calorimetry were used to characterize interactions between hyaluronan and arginine oligomers. The molecular weight of arginine oligomer plays an important role in interactions with hyaluronan. Interactions were observable for arginine oligomers with eight monomer units and longer chains. The effect of the ionic strength and molecular weight of hyaluronan on interactions was tested. In an environment with increased ionic strength, the length of the arginine oligomer was crucial. Generally, sufficiently high ionic strength suppresses interactions between hyaluronan and arginine oligomers, which demonstrated interactions in water. From the point of view of the molecular weight of hyaluronan, the transition between the rod conformation and the random coil conformation appeared to be important

High-Resolution Ultrasonic Spectroscopy: Looking at the Interpolyelectrolyte Neutralization from a Different Perspective

In this study, the high-resolution ultrasonic spectroscopy (HR-US) technique was applied to examine interpolyelectrolyte neutralization. The mentioned method was tested on the example of complexation between poly(allylammonium) cations and poly(acrylate) anions in aqueous solutions at pH = 7. It was confirmed by HR-US that the type of titration (stepwise or abrupt), the direction of titration, and the type of background salt affect the outcome of interpolyelectrolyte neutralization. The obtained results were explained on the basis of ultrasonic velocity and attenuation changes in the context of suspension compressibility, a parameter that is extremely sensitive to molecular organization and intermolecular interactions. Moreover, the results of HR-US measurements proved to be consistent with previous results obtained by more traditional methods such as dynamic light scattering, microcalorimetry, and electrokinetics. This research demonstrates that HR-US is a convenient and reliable method that can be employed for the investigation of interpolyelectrolyte neutralization and polyelectrolyte-related processes