Xylan is a highly available bioresource present in hardwoods and non-wood lignocellulosic biomass. It can easily be obtained as a by-product of pulp production or by upgrading paper pulp to dissolving quality by cold-alkali extraction. However, valorization strategies for xylan are highly needed to justify the added costs for adopting xylan extraction and purification processes. Chemical functionalization of xylan to derivatives and shaping into functional materials are very attractive approaches in this regard. The aim of the present study was to prepare novel activated nanomaterials from xylan phenyl carbonates (XPhC). It is demonstrated that the PhC group (i) is easily introduced by homogeneous derivatization, (ii) is hydrophobic and thus should enable facile self-assembling into spherical nanoparticles (NP), and (iii) can be converted with nucleophilic amines to introduce various functionalities (e.g., dyes, drugs, antibodies) prior or subsequent to the NP formation. XPhC with high degrees of substitution (DS) of up to 2.0 were prepared in completely homogeneous reactions using different reaction media. Spectroscopic characterization revealed different substitution pattern for the products: statistic (in ionic liquids) vs. preferential at position 3 (in dipolar aprotic solvent with LiCl). Xylans from different origin were included in this study to investigate the effect of molecular weight and monosaccharide composition on the xylan carbonate synthesis and likewise evaluate the potential for adding value to different processes in which xylan could be derived as a by-product. Finally, the quantitative conversion of the activated XPhC into carbamates was studied with different nucleophilic amines. Using a dialysis approach, spherical XPhC-NP were obtained with a Z-average diameter of ≈ 100-300 nm and a narrow polydispersity (PDI ≈ 0.1). It could be demonstrated that the activated PhC groups are not cleaved during the particle formation. Thus, it is possible to functionalize these “activated-NP” for specific applications (e.g., drug delivery, bio-sensoring, immunoassays). Surprisingly, cellulose phenyl carbonates were not suitable for the preparation of NP, which clearly indicates the possibilities for integrating xylan into high-value added nanomaterials with unique fields of application.

Activated polysaccharide nanoparticles derived from xylan phenyl carbonates – From synthesis to applications

253rd National Meeting (2017)

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