Synthesis and Characterization of a Cationic Poly(β-hydroxyalkanoate)

Abstract

Poly(beta-hydroxyalkanoates) (PHAs) are biodegradable polyesters produced by a wide range of bacteria. The structures of these polymers may be tuned by controlling the carbon source composition in the feed stock, but the range of functional groups accessible in this manner is limited to those that the organism is able to metabolize. Much effort has been made to chemically modify the side chains of these polymers to achieve new materials. Here, we report the synthesis of the first cationic PHA, poly(beta-hydroxy-octanoate)- co-(beta-hydroxy-11-(bis(2-hydroxyethyl)-amino)-10-hydroxyundecanoate) (PHON). Pseudomonas putida Gpo1 was used to produce poly(beta-hydroxy-octanoate)- co-(beta-hydroxy-10-undecenoate) (PHOU), whose vinyl-terminated side chains were first converted to terminal epoxides and then modified with diethanolamine. The modification of PHOU was examined using (1)H, COSY, and HSQC NMR and GPC and resulted in a loss of molecular weight due to aminolysis and also in the introduction of side chains terminated with tertiary amine groups, which are protonated at physiological pH. The polycationic PHA is soluble in polar solvents such as DMSO, DMF, and water. The new biodegradable cationic polymers are envisioned as nucleic acid delivery systems.

Water soluble polyhydroxyalkanoates: future materials for therapeutic applications

“…5 This reaction can proceed to complete conversion of the unsaturated double bonds in PHOU (Fig. 7 The successful side chain conversion was further accompanied by the change in solubility. With the increase in percentage of the pendant hydroxyl groups, the modified PHOU showed good solubility in polar solvents such as ethanol and methanol, and almost full solubility in water was also achieved.…”

Synthetic routes to degradable copolymers deriving from the biosynthesized polyhydroxyalkanoates: A mini review

“…The partially hydroxylated (50~60%) PHU being treated with potassium permanganate at 20°C was completely soluble in polar solvents (80/20 acetone/water, methanol or dimethyl sulfoxide), indicating a considerably enhanced hydrophilicity [42]. Epoxides-terminated side chains being converted from the vinyl terminal of PHU has been reported to be modified with diethanolamine to obtain a cationic PHA with pendant amine side groups [43,44]. When exposed to air at room temperature for 40 days, the unsaturated copolyester formed a highly flexible and biocompatible elastomer [45].…”

Amphiphilic Poly(3-hydroxy alkanoate)s: Potential Candidates for Medical Applications

“…Reaction between hexamethylene diamine with epoxidized PHOU provides cross-linked polyester [41]. Enhenced hydrophilicity of the PHOU has recently been achieved by the reaction between epoxidized PHOU and diethanol amine to give highly hydrophilic polyester, PHON [42]. The first reaction involved the transformation of the vinyl-terminated side chains of PHOU to epoxide groups (PHOE).…”