Synthesis and characterization of castor oil-derived oxidation-responsive amphiphilic block copolymers: Poly(ethylene glycol)-b-poly(11-((2-hydroxyethyl)thio)undecanoate)

Identifier:  imarina:6390050

Handle: https://hdl.handle.net/20.500.11797/imarina6390050

Authors:  Valverde, C; Lligadas, G; Ronda, JC; Galià, M; Cádiz, V

Abstract:
© 2020 Elsevier Ltd The synthesis of oxidation-responsive biodegradable amphiphilic block copolymers by Candida Antarctica Lipase B (CALB)-catalyzed self-polycondensation of 11-((2-hydroxyethyl)-thio)undecanoic acid (TEHA) initiated by methoxy polyethyleneglycol (mPEG-OH) of different molecular weights has been described. SEC and mono and bidimensional NMR have been used to confirm the molecular weight and structure of the polymers and copolymers. DSC and TGA have been employed to characterize their thermal properties. The oxidation behaviour in front of H2O2 as well as the structure of the oxidized products has been established using NMR, FTIR and Raman spectroscopies. The different block copolymers could self-assemble to form nanosized micelles in aqueous solution with low critical micelle concentration (CMC), showing potential application as dual responsive systems in drug delivery. Micellar characteristics were investigated by dynamic light scattering (DLS) and transmission electron microscopy (TEM). These micelles are prone to undergo a H2O2-triggered disassembly due to the oxidizable thioether groups in the hydrophobic core. Nile Red was used as model for hydrophobic drugs to test the oxidative triggered release of a copolymer, which showed progressive release in few hours upon the addition of H2O2.