Amphiphilic xylan-cholic acid conjugates: synthesis and self-assembly behaviors in aqueous solution

A novel amphiphilic biopolymer was synthesized by incorporating hydrophobic segment cholic acid (CA) into hydrophilic segment carboxymethyl xylan (CX) through coupling agent. Structural characteristics and self-assembly behaviors of the amphiphilic conjugates in aqueous solution were investigated in detail. Results showed that the conjugates provided monodispersed self-assembled micelles in distilled water, with average diameters in the range of 90-135 nm, depending on the DS of CA. TEM and AFM images proved that the self-assembly micelles were spherical. The micelles were covered with negatively charged carboxymethyl xylan shells, exhibiting zeta potential about - 38 mV. The aggregation concentration of the conjugate (0.0079-1.25 x 10(-2) g/L) was closely related to the DS of CA and solution pH. Moreover, CX-CA nanoparticles were sensitive to the pH of release media. The cellular uptake of DOX-loaded CX-CA nanoparticles was better than that of free DOX, and thus CX-CA nanoparticles can be used as a new carrier for antitumor drug delivery.