Tannic acid decorated poly(methacrylic acid) micro and nanoparticles with controllable tannic acid release and antioxidant properties

Abstract

Poly(methacrylic acid), p(MA), particles in the size range of nano and micrometer were prepared via emulsion and reverse suspension polymerization method, respectively. Ethylene glycol dimethacrylate (EGDMA) as a biodegradable cross-linker was used in the preparation of these p(MA) particles. Both nano and micrometer p(MA) particles were decorated with tannic acid (TA) via a direct esterification linkage upon activation of the carboxylic acid with N,N′-carbonyldiimidazole followed out by conjugation with TA to obtain p(MA)-TA. For the characterization of the particles TGA, FT-IR SEM, and light microscope were used. In vitro release of the TA from p(MA)-TA conjugates were investigated at pH 7.4 in phosphate buffered saline (PBS) by UV–vis spectrometer and result revealed that the amount of the used crosslinker has paramount significance in degradation of TA molecules. For example, p(MA)-TA microparticles with 1% of the crosslinking density released 83.24mg TA per g particles in comparison to nanosizes p(MA)-TA particles with 10% of the crosslinking density that released 35.21mg per g particles within four days. Additionally, antioxidant properties of all particles were evaluated by Total Phenol Content (TPC) and Trolox Equivalent Antioxidant Concentration (TEAC) methods and found that the p(MA)-TA microparticles has great antioxidant properties with TPC=61.41±1.44mgL−1 gallic acid equivalent (GAE), TEAC=248.82±1.96mMtroloxg−1 for dry sample.