X-ray visible microspheres derived from highly branched biodegradable poly(lactic acid) terminated by triiodobenzoic acid: Preparation and degradation behavior

Biodegradable polyesters with X-ray visibility for biomedical applications have attracted increasing attention. We herein reported a facile method of end-chain functionalization to prepare highly branched linear-comb poly (lactic acid) (Lc-PLA) using triiodobenzoic acid (TIBA) as end-capping and X-ray contrast agent. Three branch lengths of iodinated linear-comb poly (lactic acid) (I-Lc-PLA 30k , I-Lc-PLA 50k , and I-Lc-PLA 70k ) were successfully synthesized and then microspheres with well-controlled size (average size ~180 μm) were prepared. By micro-CT testing, the results showed that shorter branch length of PLA contributed more iodinated end-group functionalized sites, leading a relatively high iodine content and excellent radiopacity. After terminated with TIBA, glass transition temperature and thermal stability of I-Lc-PLA polymers were greatly improved. During the in vitro hydrolytic degradation of three months, the molecular weight , iodine content, surface microstructure and micro-CT radiopacity of these microspheres were investigated. The degradation results showed that I-Lc-PLA 50k possessed sufficient iodine content and high household unit values, suggesting a well-maintained radiopacity of I-Lc-PLA. Therefore, this work proposed a highly branched I-Lc-PLA microspheres with promising CT-imaging capacity, which could be used as a long-term embolic material.