Effect of surfactants on surface activity and rheological properties of type I collagen at air/water interface.
We describe the effect of three synthetic surfactants (anionic - sodium dodecyl sulfate (SDS), cationic - cetyltrimethylammonium bromide (CTAB) and nonionic - Triton X-100 (TX-100)) on surface properties of the type I calf skin collagen at the air/water interface in acidic solutions (pH 1.8). The protein concentration was fixed at 5×10-6molL-1and the surfactant concentration was varied in the range 5×10-6molL-1-1×10-4molL-1, producing the protein/surfactant mixtures with molar ratios of 1:1, 1:2, 1:5, 1:10 and 1:20. An Axisymmetric Drop Shape Analysis (ADSA) method was used to determine the dynamic surface tension and surface dilatational moduli of the mixed adsorption layers. Two spectroscopic techniques: UV-vis spectroscopy and fluorimetry allowed us to determine the effect of the surfactants on the protein structure. The thermodynamic characteristic of the mixtures was studied using isothermal titration calorimetry (ITC) and differential scanning calorimetry (DSC). Modification of the collagen structure by SDS at low surfactant/protein ratios has a positive effect on the mixture's surface activity with only minor deterioration of the rheological properties of the adsorbed layers. The collagen/CTAB mixtures do not show that pronounced improvement in surface activity, while rheological properties are significantly deteriorated. The mixtures with non-ionic TX-100 do not show any synergistic effects in surface activity.
Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664, Warsaw, Poland.
Aleksandra
A
Kezwoń
Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664, Warsaw, Poland.
Ilona
I
Góral
Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, 02-106 Warsaw, Poland.
Tomasz
T
Frączyk
Faculty of Chemistry, Warsaw University of Technology, Noakowskiego 3, 00-664, Warsaw, Poland. Electronic address: kamil.wojciechowski@ch.pw.edu.pl.
Kamil
K
Wojciechowski
D000388:Air; D002152:Calorimetry, Differential Scanning; D024042:Collagen Type I / Q000378:metabolism*; D012212:Rheology; D013056:Spectrophotometry, Ultraviolet; D013500:Surface Tension; D013501:Surface-Active Agents / Q000737:chemistry*; D014867:Water
D024042:Collagen Type I; D013501:Surface-Active Agents; D014867:Water
CTAB; Calorimetry; Fluorimetry; SDS; Spectrophotometry; Surface dilatational rheology; Surface tension; TRITON X-100; Type I calf skin collagen