Fully biosourced amphiphilic block copolymer from tamarind seed xyloglucan and solanesol: synthesis, aqueous self-assembly, and drug encapsulation.

This study aims to explore the development of natural bio-based amphiphilic block copolymers for drug delivery applications. We investigated block copolymers derived from tamarind seed xyloglucan and solanesol, focusing on their synthesis, structural analysis, aqueous self-assembly, and drug encapsulation. Specifically, xyloglucan hydrolysate segments with number-average degrees of polymerization (DPs) of between 8 and 44 (XOS, XMS, XMS, XMS, and XMS) were used as the hydrophilic blocks, whereas plant-sourced solanesol was selected as the hydrophobic segment. These two segments were linked via click chemistry to create novel XOS-b-Sol and XMS-b-Sol copolymers, where XOS refers to a xyloglucan oligosaccharide (DP < 10), and XMS denotes a megalosaccharide, defined as a larger xyloglucan polymer with a DP >10. XMS- and XMS-b-Sol self-assembled in aqueous media to form predominantly narrowly dispersed spherical micelles, while XOS-b-Sol exhibited a combination of short wormlike structures and spherical micelles. Small-angle X-ray scattering, multi-angle dynamic light scattering, and transmission electron microscopy revealed the XMS- and XMS-b-Sol micelles are morphologically diverse. XMS-b-Sol solubilized quercetin, a water-insoluble flavonoid, highly effectively, highlighting its potential as an environmentally benign drug carrier.