Guanidinylated chitosan inspired by arginine-rich cell-penetrating peptides.

Abstract We introduce a simple method for producing guanidinylation of chitosan (CS) with 1‑amidinopyrazole hydrochloride (AP). Production of GCS is proved via NMR, IR, and elemental analyses. In a reaction using 4.5 eq of AP for 7 days at room temperature, we obtained GCS with 42.3% of degree of guanidinylation (DG). The DG value can be controlled by the reaction time and AP amount. Furthermore, remarkable enhancement of the interaction between GCS and bovine serum albumin by guanidinylation was observed. This simple guanidinylation method for CS could provide novel additives for protein/peptide delivery systems. Highlights • Guanidinylation of chitosan with 1‑amidinopyrazole hydrochloride was investigated. • High degree of guanidinylation (42.3%) was achieved with a simple method. • Effect of guanidino groups on BSA-binding was investigated with fluorescence spectra. • Guanidino groups enhanced the interaction with BSA in neutral pH remarkably. [ABSTRACT FROM AUTHOR]