Development of poly(lactic-co-glycolic acid) microparticles with pH-sensitive drug release behaviors

We developed a novel pH-sensitive microparticle using poly(lactide-co-glycolide) (PLGA) and 3-diethylaminopropylated poly( l -lysine) [poly(Lys-DEAP)] (pK b of DEAP ~6.5). Here, the design of the microparticle takes advantage of the unique pH-sensitive feature of poly(Lys-DEAP) as either a non-ionic characteristic of DEAP moieties at pH 7.4 or an ionic characteristic of DEAP moieties at acidic pH. In particular, the ionized DEAP in PLGA microparticles modulated acidic pH-activated microparticle-destruction and allowed accelerated release of the encapsulated drug content when the pH of the solution was decreased to from 7.4 to 6.8 or 6.0. We believe that this microparticle system is expected to improve the treatment efficacy for lung diseases with chronic respiratory acidosis.