Abstract
Monitoring multiple biological interactions in a multiplexed array format has numerous advantages. However, converting well-developed surface chemistry for spectroscopic measurements to array-based high-throughput screening is not a trivial process and often proves to be the bottleneck in method development. This paper reports the fabrication and characterization of a new carbohydrate microarray with synthetic sialosides for surface plasmon resonance imaging (SPRi) analysis of lectin-carbohydrate interactions. Contact printing of functional sialosides on neutravidin-coated surfaces was carried out and the properties of the resulting elements were characterized by fluorescence microscopy and atomic force microscopy (AFM). Sambucus nigra agglutinin (SNA) was deposited on four different carbohydrate functionalized surfaces and differential binding was analyzed to reveal affinity variation as a function of headgroup sialic acid structures and linking bonds. SPRi studies indicated that this immobilization method could result in high quality arrays with RSD < 5% from array element to array element, superior to the conventional covalent linkage used for protein cholera toxin (CT) in a comparison experiment, which yields nonuniform array elements with RSD > 15%. Multiplexed detection of SNA/biotinylated sialoside interactions on arrays up to 400 elements has been performed with good data correlation, demonstrating the effectiveness of the biotin-neutravidin-based biointerface to control probe orientation for reproducible and efficient protein binding to take place. Additionally, the regeneration of the array surface was demonstrated with a glycine stripping buffer, rendering this interface reusable. This in-depth study of array surface chemistry offers useful insight into experimental conditions that can be optimized for better performance, allowing many different protein-based biointeractions to be monitored in a similar manner.
