Thermo-sensitive random poly(L-alanine-co-L-lactic acid) with no cytotoxicity by the structure-controlled synthesis for a nano-drug carrier

摘要

A random poly(L-alanine-co-L-lactic acid) (PAL) with excellent thermo-sensitivity and no cytotoxicity was synthesized by the structure-controlled polycondensation from natural L-alanine and L-lactic acid. Only those PALs in which the contents of L-alanine structural unit are rigidly controlled in the smaller range of 53-65% show a reversible lower critical solution temperature of 35-60 degrees C. The change of secondary structure in poly(L-alanine) segments by the introduction of L-lactic acid structural unit plays a decisive role in regulating the thermo-sensitivity of PAL. The viability of HeLa cells exposed to PAL reaches up to 91-116% after incubation of 24 and 72h, indicating no cytotoxicity. Furthermore, PAL can easily form curcumin-loaded nano-carriers through its thermo-sensitivity and self-assembly. The curcumin-loaded PAL nano-particles are observed to clearly internalize into the cells by confocal laser-scanning microscopy, and thus can be used as a potential nano-drug-carrier.