Naslov
The thermodynamic study of interpolyelectrolyte and protein-polyelectrolyte complexes

Autori
Požar, Josip ; Štajner, Lara ; Kremer, Tomislav ; Kovačević, Davor

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
29th Conference of the European Colloid and Interface Society (ECIS), Bordeaux, Francuska, 6. – 11. 9. 2015. / - , 2015, 1-1

Skup
29th Conference of the European Colloid and Interface Society (ECIS)

Mjesto i datum
Bordeaux, Francuska, 06.09.2015. - 11.09.2015

Vrsta sudjelovanja
Poster

Vrsta recenzije
Nije recenziran

Ključne riječi
polyelectrolytes ; proteins ; complexation ; microcalorimetry

Sažetak
It is well-known that mixing of aqueous solutions of oppositely charged polyelectrolytes, as well as oppositely charged proteins and polyelectrolytes, leads to the formation of aggregates often called polyelectrolyte or protein-polyelectrolyte complexes. We systematically investigated the complexation of sodium poly(allylammonium) chloride (PAH) with a strong polyanion sodium poly(styrenesulfonate) (PSS) and with a weak polyanion poly(acrylic acid) (PAA). Additionally, the interactions between lysozyme and PSS, as the model system for investigating protein-polyelectrolyte complexation processes, were examined. The heat effects of abovementioned processes were determined by isothermal titration microcalorimetry. Electrophoretic mobility and particle size measurements were also applied. The influence of electrolyte type, ionic strength, pH, reactant concentration and titration direction (addition order) on complexation was investigated at t = 25 ºC In all experiments complexation was found to be predominantly entropically driven, irrespectively of the type of reaction products formed (polyelectrolyte complexes, precipitates), electrolyte type, addition order and concentration. For PAH-PSS complexation the correlation between obtained reaction enthalpies for complex and precipitate formation with anion hydration enthalpies was observed and the product formation was the least enthalpically favorable in solutions containing weakly hydrated NO3 and ClO4 anions. For lysozyme-PSS complexation the process is notably more exothermic at pH = 3.1 than at pH = 7.5. Somewhat surprisingly, the formation of protein-polyelectrolyte complexes seems to be notably more favorable than that of PSS-PAH. The cumulative enthalpy changes per monomer of PSS were found to be 22 kJ mol-1, contrary to almost isoenthalpic pairing of PAH with PSS. Such differences are most likely caused by the more pronounced counterion condensation in solution of two strongly charged polyelectrolytes, than in solution of lysozyme and PSS.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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