Chemoenzymatic Synthesis of Galectin Binding Glycopolymers.

Chemoenzymatic synthesis is an important strategy for the formation of glycopolymers. The use of a smaller number of traditional chemical steps and enzyme catalyzed reactions increases the yield of glycopolymer that can be produced by reducing the overall number of synthetic steps. In addition, chemoenzymatic routes are likely to be more accessible to those without a background in carbohydrate synthesis, making glycopolymers more available for studies across a broader range of scientists. Here, the enzymatic addition of galactose to N-acetylglucosamine functionalized glycodendrimers reduced the requisite number of synthetic steps for the full chemical synthesis of N-acetyl lactosamine (Lac NAc) functionalized dendrimers to four steps. Unpurified cell lysate was used in the enzyme catalyzed glycosylation, and product glycodendrimers were readily purified by dialysis after enzymatic degradation of all protein components of the lysate in the crude reaction mixture. Lac NAc functionalized dendrimers were used very effectively in homotypic cancer cellular aggregation assays and were found to either inhibit or enhance galectin-3 mediated cancer cellular aggregation, with differences in outcomes dependent on the generation of Lac NAc functionalized dendrimers that were used.

Cyclodextrin-functionalized chromatographic materials tailored for reversible adsorption.

Novel dendronized silica substrates were synthesized. First- and second- generation polyaryl ether dendrons were appended to silica surfaces. Using Cu(I) mediated cycloaddition "click" chemistry, ß-cyclodextrin was tethered to the dendronized surfaces and to a nondendronized surface for comparison purposes. This synthesis strategy affords a modular, versatile method for surface functionalization in which the density of functional groups can be readily varied by changing the generation of dendron used. The surfaces, which are capable of adsorbing target analytes, have been characterized and studied using X-ray photoelectron spectroscopy (XPS) and vibrational sum frequency spectroscopy (VSFS). Fluorescence spectroscopy was used to study the surfaces' ability to retain coumarin 152 (C152). These studies indicated that the ß-cyclodextrin functionalized surfaces not only adsorbed C152 but also retained it through multiple aqueous washes. Furthermore, these observations were quantified and show that substrates functionalized with first-generation dendrons have a more than 6 times greater capacity to adsorb C152 than slides functionalized with monomeric ß-cyclodextrin. The first-generation dendrons also have 2 times greater the capacity than the larger generation dendrons. This result is explained by describing a dendron that has an increased number of ß-cyclodextrin monomers but, when covalently bound to silica, has a footprint too large to optimize the number of accessible monomers. Overall, both dendronized surfaces demonstrated an increased capacity to adsorb targeted analytes over the slides functionalized with monomeric ß-cyclodextrin. The studies reported provide a methodology for characterizing and evaluating the properties of novel, highly functional surfaces.