Degradation of poly(butylenes succinate) as a novel biomaterial in vitro

Background: Poly(butylene succinate) (PBS) has also been known as an important biodegradable aliphatic polyester because of its good degradation properties, excellent physical properties and molding processability. Therefore, its potential application as a novel biomaterial has been concerned and expected to be used as the drug carriers in controlled delivery and the scaffold materials in tissue engineering. Objective: To verify the degradation behavior of the biodegradable PBS in vitro. Design, time and setting: The experiment, an unitary sample observation, was conducted in the State Engineering Research Center of Engineering Plastics, Institute of Physics and Chemistry, Chinese Academy of Sciences (Beijing, China) from June to November in 2007. Materials: PBS was synthesized by melt phase polycondensation of 1,4-butanediol and succinic acid, then purified in the sequence of being dissolved in chloroform, precipitated in methanol, and dried in a vacuum at 60 ° C for 48 hours. Methods: The average thickness of 100 μ in PBS film was prepared by heat-processing method using plate vulcanization machine, and then cut into pieces of 1 cm×1 cm area. The evaluation of PBS film degradation behavior was carried out in the phosphate-buffered saline (pH 7.4). Main outcome measures: The changes in weight, molecular weight, pH value and surface structures of PBS were examined. Results: PBS films degraded in the phosphate-buffered saline solution. The degradation process exhibited two phases: The degradation in the first phase was slow in 0-9 weeks, and the process accelerated in the second phase of 9-15 weeks. Unlike the weight change, the molecular weight of the PBS films decreased immediately and continually throughout the time course. The pH value of the phosphate-buffered saline solution remained between 6.0 and 8.0 though an increase appreciably after degradation, which resulted from the acid degradation products of the polymer. The PBS films became rough and a large number of small cracks appeared, with many round eroded regions formed at 12 weeks. The cracks enlarged and the round regions evolved into holes after 15 weeks. The results showed that the PBS degraded with the same behavior as that of the degradable poly(a-hydroxyesters). Conclusion: The PBS films degrade in the phosphate-buffered saline solution and create acid products. The degradation process includes lag phase and acceleration phase.