Synthesis of novel (bio) degradable linear azo polymers conjugated with olsalazine

Abstract

Click Cu(I)-catalyzed polymerization of diynes and diazides was performed to obtain a novel type of linear copolymer, which were prepared from monomers derived from poly(ethylene glycol), 5, 5′-azodisalicylic acid [olsalazine] and 1,4-butanediol diglycidyl ether. The resulting copolymers will carry ester and azo functions along the polymer backbone, so they will be sensitive to pH as well as be degraded by azoreductase enzymes present in the colonic microbiota. Most of the copoly(azoester triazole)s obtained were water soluble, and all of them were characterized by Fourier transform infrared, nuclear magnetic resonance (NMR), and gel permeation chromatography (GPC). Differential scanning calorimetry (DSC) revealed them to be amorphous, and in general, the polymers were stable up to 250 °C under nitrogen as demonstrated by thermogravimetric analysis (TGA). The degradation behavior of the polymers was evaluated in vitro. Degradation studies were carried out at 37 °C in buffered salt solution at pH 7.4, and were monitored by GPC and NMR spectroscopies. A biodegradation experiment of a water-soluble prototype polymer showed that they are biodegradable via a strain of Enterococcus faecalis. The experiment was monitored using ultraviolet–visible spectroscopy.