Interactions of bovine serum albumin with ethylene oxide/butylene oxide copolymers in aqueous solution.
The interactions of bovine serum albumin (BSA) with three ethylene oxide/butylene oxide (E/B) copolymers having different block lengths and varying molecular architectures is examined in this study in aqueous solutions. Dynamic light scattering (DLS) indicates the absence of BSA-polymer binding in micellar systems of copolymers with lengthy hydrophilic blocks. On the contrary, stable protein-polymer aggregates were observed in the case of E 18B 10 block copolymer. Results from DLS and SAXS suggest the dissociation of E/B copolymer micelles in the presence of protein and the absorption of polymer chains to BSA surface. At high protein loadings, bound BSA adopts a more compact conformation in solution. The secondary structure of the protein remains essentially unaffected even at high polymer concentrations. Raman spectroscopy was used to give insight to the configurations of the bound molecules in concentrated solutions. In the vicinity of the critical gel concentration of E 18B 10 introduction of BSA can dramatically modify the phase diagram, inducing a gel-sol-gel transition. The overall picture of the interaction diagram of the E 18B 10-BSA reflects the shrinkage of the suspended particles due to destabilization of micelles induced by BSA and the gelator nature of the globular protein. SAXS and rheology were used to further characterize the structure and flow behavior of the polymer-protein hybrid gels and sols.
Kelarakis
Antonios
A
National and Kapodistrian University of Athens, Department of Chemistry, Physical Chemistry Laboratory, Panepistimiopolis, 157 71 Athens, Greece. akelar@cc.uoa.gr
Castelletto
Valeria
V
Krysmann
Marta J
MJ
Havredaki
Vasiliki
V
Viras
Kyriakos
K
Hamley
Ian W
IW
D000818:Animals; D004852:Epoxy Compounds / Q000737:chemistry*; D005782:Gels; D008823:Micelles; D044367:Phase Transition; D011092:Polyethylene Glycols / Q000737:chemistry*; D011487:Protein Conformation; D012710:Serum Albumin, Bovine / Q000737:chemistry*; D012996:Solutions; D014867:Water
D004852:Epoxy Compounds; D005782:Gels; D008823:Micelles; D012996:Solutions; D014867:Water; C087757:poly(ethylene oxide)-poly(butylene oxide) copolymer; D012710:Serum Albumin, Bovine; D011092:Polyethylene Glycols