Concise preparation and properties of the functional material polylactic acid modified by cystamine

Polylactic acid (PLA) is one of promising biocompatible and biodegradable polyesters. Cystamine (Cys) is a non-toxic simple compound containing disulfide bond. Polymermaterials containing disulfide bond used for drug delivery can undergo reduction reaction, leading to structural disintegration and the release of loaded drugs to achieve targeted drug transport and controlled delivery. To enrich the application of PLA and develop the preparation method of functional PLA material, a series of polymer PLACs were successfully prepared from lactic acid (LA) and Cys through direct melt polycondensation in a one-pot process. The structure and performance of the polymer PLACs were studied systematically. The results indicated that the disulfide bond can be smoothly incorporated into polymeric chain through the simple condensation of LA and Cys. The performances of polymer PLACs can be controlled by adjusting the feed ratio within a certain feed ratio range. Importantly, the -S-S-bond can be cleaved by the reducing agent dithiothreitol (DTT), resulting the corresponding PLA material with terminal thiol groups. When the ratio of n(LA) to n(Cys) is 30 to 1, the polymerization is optimal. Therefore, this method is expected to further facilitate the rapid formation of functional PLA telechelic polymer with disulfide bonds. Furthermore, PLACs have potential applications in the encapsulation and controlled release of disulfide bonds-containing molecules for systemic circulation in vivo.