Preparation,Thermostability, and Degradation In Vitro of Polylactides Bearing Porphyrins

Polylactide (PLA) bearing hemin coupling moieties was prepared by a reaction between the two carboxylic groups of hemin and amino groups of amino-terminated PLA and characterized by UV-Vis, IR, and ¹H NMR spectra and gel permeation chromatography. Blank microparticles and microparticles loaded with bovine serum albumin (BSA), both of PLA bearing hemin, were prepared and characterized by solid UV-Vis spectra and thermogravimetric analysis (TGA). The effects of hemin on thermostability and degradation of microparticles of PLA were studied using TGA and a degradation experiment in vitro. These experiments showed that the introduction of porphyrin rings into PLA molecules led to the reduction of thermostability, a greater degradation of the polymer than the original polymer under the same condition in vitro, and a higher ability of the polymer binding to BSA molecules. These results should be of use in biodegradable polymer design and photodynamic therapy studies of porphyrin derivatives.