Characterization of protein immobilization at silver surfaces bynear edge x-ray absorption fine structure spectroscopy
Ribonuclease A (RNase A) is immobilized on silver surfacesin oriented and random form via self-assembled monolayers (SAMs) ofalkanethiols. The immobilization process is characterized step-by-stepusing chemically selective near-edge X-ray absorption fine structurespectroscopy (NEXAFS) at the C, N, and S K-edges. Causes of imperfectimmobilization are pinpointed, such as oxidation and partial desorptionof the alkanethiol SAMs and incomplete coverage. The orientation of theprotein layer manifests itself in an 18 percent polarization dependenceof the NEXAFS signal from the N 1s to pi* transition of the peptide bond,which is not seen for a random orientation. The S 1s to C-S sigma*transition exhibits an even larger polarization dependence of 41 percent,which is reduced to 5 percent for a random orientation. A quantitativemodel is developed that explains the sign and magnitude of thepolarization dependence at both edges. The results demonstrate thatNEXAFS is able to characterize surface reactions during theimmobilization of proteins and to provide insight into their orientationson surfaces.
- Research Organization:
- COLLABORATION - University ofWisconsin-Madison
- DOE Contract Number:
- DE-AC02-05CH11231
- OSTI ID:
- 928875
- Report Number(s):
- LBNL-63059; LANGD5; TRN: US200811%%364
- Journal Information:
- Langmuir, Vol. 22, Issue 18; Related Information: Journal Publication Date: AUG 29 2006; ISSN 0743-7463
- Country of Publication:
- United States
- Language:
- English
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