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Imaging Analysis of Carbohydrate-Modified Surfaces Using ToF-SIMS and SPRi
Whitman College, 345 Boyer Ave., Walla Walla, WA 99362, USA
Department of Bioengineering, University of Washington, Seattle, WA 98195, USA
NESAC/Bio, University of Washington, Seattle, WA 98195, USA
These authors contributed equally to this work.
* Author to whom correspondence should be addressed.
Received: 4 June 2010; in revised form: 28 June 2010 / Accepted: 1 July 2010 / Published: 7 July 2010
Abstract: Covalent modification of surfaces with carbohydrates (glycans) is a prerequisite for a variety of glycomics-based biomedical applications, including functional biomaterials, glycoarrays, and glycan-based biosensors. The chemistry of glycan immobilization plays an essential role in the bioavailability and function of the surface bound carbohydrate moiety. However, the scarcity of analytical methods to characterize carbohydrate-modified surfaces complicates efforts to optimize glycan surface chemistries for specific applications. Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) is a surface sensitive technique suited for probing molecular composition at the biomaterial interface. Expanding ToF-SIMS analysis to interrogate carbohydrate-modified materials would increase our understanding of glycan surface chemistries and advance novel tools in the nascent field of glycomics. In this study, a printed glycan microarray surface was fabricated and subsequently characterized by ToF-SIMS imaging analysis. A multivariate technique based on principal component analysis (PCA) was used to analyze the ToF-SIMS dataset and reconstruct ToF-SIMS images of functionalized surfaces. These images reveal chemical species related to the immobilized glycan, underlying glycan-reactive chemistries, gold substrates, and outside contaminants. Printed glycoarray elements (spots) were also interrogated to resolve the spatial distribution and spot homogeneity of immobilized glycan. The bioavailability of the surface-bound glycan was validated using a specific carbohydrate-binding protein (lectin) as characterized by Surface Plasmon Resonance Imaging (SPRi). Our results demonstrate that ToF-SIMS is capable of characterizing chemical features of carbohydrate-modified surfaces and, when complemented with SPRi, can play an enabling role in optimizing glycan microarray fabrication and performance.
Keywords: carbohydrate microarray; ToF-SIMS; SPR; glycomics
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Bolles, K.M.; Cheng, F.; Burk-Rafel, J.; Dubey, M.; Ratner, D.M. Imaging Analysis of Carbohydrate-Modified Surfaces Using ToF-SIMS and SPRi. Materials 2010, 3, 3948-3964.
Bolles KM, Cheng F, Burk-Rafel J, Dubey M, Ratner DM. Imaging Analysis of Carbohydrate-Modified Surfaces Using ToF-SIMS and SPRi. Materials. 2010; 3(7):3948-3964.
Bolles, Kathryn M.; Cheng, Fang; Burk-Rafel, Jesse; Dubey, Manish; Ratner, Daniel M. 2010. "Imaging Analysis of Carbohydrate-Modified Surfaces Using ToF-SIMS and SPRi." Materials 3, no. 7: 3948-3964.