XPS and SPR analysis of glycoarray surface density

Citation

Dhayal, M. & Ratner, D. M. (2009). XPS and SPR analysis of glycoarray surface density. Langmuir, 25(4), 2181-2187. PMCID: 2719674

Abstract

Despite the fact that the carbohydrate microarray has seen increasing use within the field of glycobiology, the surface chemistry of the glycoarray remains largely unexplored. Motivated by the need to develop surface analytical techniques to characterize carbohydrate-modified surfaces, we developed a quantitative X-ray photoelectron spectroscopy (XPS) and surface plasmon resonance imaging (SPR imaging) method to study glycan biosensors. We performed a comparative analysis on the relative coverage of mixed self-assembled monolayers (SAMs) on gold, consisting of a thiol-functionalized trimannoside (Manalpha1,2Manalpha1,2Manalpha-OEG-SH) at varying concentrations (0-100%) mixed separately with two thiol-containing polyethylene glycol oligomers. XPS C1s core level analysis was used to identify the O-C-O functionality unique to the carbohydrate acetal moiety and to separate and quantify the relative coverage of sugar in carbohydrate/OEG mixed SAMs. XPS spectra of the mixed SAMs demonstrated a proportional increase in the acetal signature of the glycan with increasing sugar concentration. To relate surface glycan density with biological function, we carried out a kinetic analysis of Concanavalin A (ConA) binding to SAMs of varying densities of carbohydrate using SPR imaging. We observed protein binding that was highly dependent on both glycan density and the nature of the OEG-thiol used in the mixed self-assembly. These results illustrate the utility of surface analytical techniques such as XPS and SPR in carbohydrate biosensor characterization and optimization.

Keyword(s)

*X-Rays
Canavalia/chemistry
Carbon/chemistry
Concanavalin A/analysis/chemistry
Glycosides/*analysis/*chemistry
Molecular Structure
Oxygen/chemistry
Spectrum Analysis/*methods
Surface Plasmon Resonance/*methods
Surface Properties

Notes

Dhayal, Marshal
Ratner, Daniel M
P41 EB002027/EB/NIBIB NIH HHS/
P41 EB002027-19/EB/NIBIB NIH HHS/
Langmuir. 2009 Feb 17;25(4):2181-7. doi: 10.1021/la8031122.

Reference Type

Journal Article

Secondary Title

Langmuir

Author(s)

Dhayal, M.
Ratner, D. M.

Year Published

2009

Date Published

1739750400

Volume Number

25

Issue Number

4

Pages

2181-2187

DOI

10.1021/la8031122

PMCID

2719674