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Micellar properties of the zwitterionic bile derivative CHAPS
M A Partearroyo1, F M Goñi, I Katime
1Department of Biochemistry, Faculty of Science, University of the Basque Country, Bilbao, Spain.
Biochemistry International
|February 1, 1988
Summary
The critical micellar concentration (cmc) of 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS) was determined. CHAPS exhibits a stable cmc across varying pH and temperature, but ionic strength significantly lowers its cmc.
Area of Science:
- Biochemistry
- Physical Chemistry
- Surfactant Science
Background:
- The zwitterionic bile derivative 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS) is a widely used non-ionic surfactant in biological and biochemical research.
- Understanding the aggregation behavior of CHAPS, specifically its critical micellar concentration (cmc), is crucial for its effective application in various experimental settings.
Purpose of the Study:
- To accurately measure the critical micellar concentration (cmc) of CHAPS using multiple techniques.
- To investigate the influence of temperature, pH, and ionic strength on the cmc of CHAPS.
Main Methods:
- Critical micellar concentration (cmc) determination using fluorescence spectroscopy, light scattering, and vapor pressure osmometry.
- Vapor pressure osmometry was identified as the most convenient and reliable method.
Main Results:
- The cmc of CHAPS in pure water at 25°C was found to be approximately 9 mM.
- A slight decrease in cmc was observed with increasing temperature, from 9 mM at 25°C to 7 mM at 50°C.
- The cmc of CHAPS remained unaffected within a pH range of 4 to 11.
- Increasing ionic strength (40 mM KCl) significantly reduced the cmc of CHAPS by approximately half.
Conclusions:
- Vapor pressure osmometry is a highly reliable method for determining the cmc of CHAPS.
- CHAPS exhibits robust micellar behavior across a broad pH and temperature range, making it a stable choice for biochemical applications.
- Ionic strength plays a significant role in modulating the aggregation properties of CHAPS, which is an important consideration for experimental design.