Beam pen lithography as a new tool for spatially controlled photochemistry, and its utilization in the synthesis of multivalent glycan arrays

Abstract

Herein, we describe how cantilever-free scanning probes can be used to deposit precursor material and subsequently irradiate the precursor to initiate polymerization, resulting in a 3D lithographic method wherein the position, height and diameter of each feature can be tuned independently. Specifically, acrylate and methacrylate monomers were patterned onto thiol terminated glass and subsequently exposed to UV light produced brush polymers by a photoinduced radical acrylate polymerization reaction. Here, we report the first examples of glycan arrays, comprised of methacrylate brush polymers that are side-chain functionalized with a-glucose, by this new lithographic approach. Their binding with fluorophore labeled concanavalin A (ConA) was assayed by fluorescence microscopy. The fluorescence of these brush polymers was compared to glycan arrays composed of monolayers of a-mannosides and a-glucosides prepared by combining polymer pen lithography (PPL) with the thiol-ene photochemical reaction or the copper-catalyzed azidealkyne cycloaddition. At high ConA concentration, the fluorescence signal of the brush polymer was nearly 20 times greater than that of the glycan monolayers, and the brush polymer arrays had a detection limit nearly two orders of magnitude better than their monolayer counterparts. Because of the ability of this method to control precisely the polymer length, the relationship between limit of detection and multivalency could be explored, and it was found that the longer polymers (136 nm) are an order of magnitude more sensitive towards ConA binding than the shorter polymers (8 nm) and that binding affinity decreased systematically with length. These glycan arrays are a new tool to study the role of multivalency on carbohydrate recognition, and the photopolymerization route towards forming multivalent glycan scaffolds described herein, is a promising route to create multiplexed glycan arrays with nanoscale feature dimensions.

Multi-dimensional glycan microarrays with glyco-macroligands

“…Most recently, Braunschweig et al employed a new approach by combining polymer pen lithiography (PPL) and beam pen lithiography (BPL) with acrylate or methacrylate photo polymerization chemistry to generate arrays of brush polymers with side chain functionalized with fluorophores or glycans [40]. They patterned acrylate and methacrylate monomers (α-mannose and α-glucoside) onto thiol coated glass slides and exposed these glass slides to UV light that produced brush polymers by a photoinduced radical acrylate polymerization reaction.…”

“…[11,13,33] Fig. 4 Glycopolymer-based glycoarray: a duel end functionalized mucin like glycopolymer with alkyne on one end and Texas Red dye on the other end [24], b mucin like glycopolymer presentation that mimics native mucin [40], c biotin end functionalized glycopolymer immobilized glass slide [26], d glycopolymer formation at different illumination times [41], e O-cyanate end functionalized glycopolymer immobilized on amine functionalized glass slide [27], f O-cyanate chain-end functionalized glycopolymer pre-complexed and immobilized with boronic acid ligands of different sizes [28]. Modified from Ref.…”

Polymer Brushes with Precise Architectures for Molecular Biorecognition

“…In a later study [116], their interaction with blood was also examined and it was found that the nature of the sugar group (Glc, Man, or Gal) has an effect on the amount and type of plasma proteins being adsorbed, with glucose-functionalized brushes leading to the lowest adsorption. Bian [117] et al reported an example of glycan arrays decorated with Concanavalin A, creating glycan-functionalized polymer brushes with pendant carbohydrate side groups by the thiol-acrylate photopolymerization. The results of this study have demonstrated that polymer brushes are better polymer scaffolds than their counterpart SAM decorated with α-mannosides and α-glucosides.…”

Carbohydrate derivative-functionalized biosensing toward highly sensitive electrochemical detection of cell surface glycan expression as cancer biomarker

“…Inspired by the concept of DNA and protein biosensors, carbohydrate-functionalized biosensors, which are composed of carbohydrate attached to a solid surface, have recently been developed as reliable and efficient tools for the assay of biological analytes (Pussak et al, 2013;Shin et al, 2005;Martin et al, 2013). This technology not only facilitates fast and sensitive analysis of a large number of biomolecules, but also effectively mimics the presentation of glycans on living cell surface to exhibit multivalent interactions with receptors (Bian et al, 2014;Mader et al, 2012). Regarding the construction of the carbohydratefunctionalized biosensor, the efficient immobilization of carbohydrates is an important factor because carbohydrates do not have functional groups (Yamada et al, 2013).…”