Polysaccharides: The “Click” Chemistry Impact

Abstract

Polysaccharides are complex but essential compounds utilized in many areas such as biomaterials, drug delivery, cosmetics, food chemistry or renewable energy. Modifications and functionalizations of such polymers are often necessary to achieve molecular structures of interest. In this area, the emergence of the "click" chemistry concept, and particularly the copper-catalyzed version of the Huisgen 1,3-dipolar cycloaddition reaction between terminal acetylenes and azides, had an impact on the polysaccharides chemistry. The present review summarizes the contribution of "click" chemistry in the world of polysaccharides.

Chemo‐enzymatic Assembly of Clickable Cellulose Surfaces via Multivalent Polysaccharides

“…[5] For example, introduction of a single functional group at one end of xyloglucan (XG, Figure 1) chains has previously been employed by our group to add a range of chemistries to diverse types of cellulose under mild conditions. Here, we elected to attach propargylamino groups via reductive amination with NaCNBH 3 , as the resulting multialkynylated conjugates [11] would be readily amenable to Cu I -catalyzed azide-alkyne cycloaddition (CuAAC, a Huisgen 1-3 dipolar cycloaddition [12] ), popularized by Sharpless and colleagues as an example of "click chemistry" (Scheme 1). [10] We reasoned that subsequent adsorption of such multivalent polysaccharide derivatives could then be used to deliver chemical payloads to cellulosic surfaces under mild conditions (aqueous solution, room temperature).…”

“…[6a, b] The resulting alkynylated brush structure opens new routes for multifunctionalization [11,22] of cellulosic surfaces, with applications in biocomposites, paper, and textile engineering, including the development of bioactive and "smart" materials. GalOx-mediated oxidation of galactose and subsequent reductive amination provides more reactive active sites per polysaccharide molecule than our previous method of reducing end modification.…”

Chitosan as an Advanced Healthcare Material

“…Th is method has to date produced a variety of chitosan-based derivatives which can have several diff erent functional groups present. Th ese modifi cations improve the utility of these polymers for various applications [16,17]. However, limitations to this reaction due to oxidative instability of Cu(I) and subsequent diffi culty of metal removal from the complexing polymer, led to the development of a metal free coupling method.…”

Synthesis of Hyperbranched Poly(ε-caprolactone) Containing Terminal Azobenzene Structure via Combined Ring-Opening Polymerization and “Click” Chemistry

“…This concept of popular "click" chemistry had attracted much attention because of its high efficiency, quantitative yield and selectivity under mild reaction conditions [25][26][27]. This novel method had been successfully applied in the area of polymer materials with different topologic structures, including linear, block, and star-shaped polymers and dendrimers [28][29][30][31][32][33][34]. In very recent years, "click" chemistry has also been used for the synthesis of hyperbranched polytriazole through step-growth polymerization.…”