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Chemoenzymatic Synthesis of Branched Glycopolymer Brushes as the Artificial Glycocalyx for Lectin Specific Binding
- Wang, Yuzhen, Gu, Lei, Xu, Fanli, Xin, Fengxue, Ma, Jiangfeng, Jiang, Min, Fang, Yan
- Langmuir 2019 v.35 no.13 pp. 4445-4452
- Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy, binding capacity, bioengineering, cell membranes, concanavalin A, contact angle, dextransucrase, glycosylation, gold, maltose, mass spectrometry, polymerization, polymers, polysaccharides, quartz crystal microbalance, sucrose
- The artificial glycocalyx fabricated by carbohydrates is of interest because it provides a platform to simulate the cell membranes that widely exist in the nature, and thus enable extensive applications to be implantable in bioengineering. Here, we present a green strategy combining two polymerization techniques, surface-initiated atom transfer radical polymerization (SI-ATRP) and enzyme-catalyzed elongation of polysaccharide, for fabricating densely packed branched glycopolymer brushes on the gold surface as the artificial glycocalyx. In this strategy, SI-ATRP is first performed to graft a linear polymer chain for anchoring maltose, which can be used as an enzyme acceptor for dextransucrase (DSase). Under DSase, a branched polysaccharide is efficiently formed through elongation of a sucrose substrate. Undoubtedly, enzymatic transglycosylation has unique advantages, such as being green, regio-, and stereo-selective, etc. The process of DSase-catalyzed polysaccharide is well monitored by a quartz crystal microbalance, and the grafting density of the glycopolymer brushes is estimated to be 0.7 chain nm–² with 23.0 nm dry thickness. The polysaccharide brushes display a branched structure consisting of α-d-glucose residues with 5% of α-1,3-linked shorter chain branches, and the branched structure is well characterized by X-ray photoelectron spectroscopy, time-of-flight secondary ion mass spectrometry, Fourier transform infrared/mirror reflection, water contact angle analysis, and atomic force microscopy. Compared with the linear maltose-anchored brushes, the branched glycopolymer analog prepared here shows high specific binding capacity of concanavalin A recognition, which should be of use in biomedical application.