Assembly and in vitro characterization of thiomeric nanoparticles

The present study focused on the assembly of an insulin exhibiting, nanoparticulate formulation and the characterization thereof regarding particle size, zeta potential and stability of nanoparticles as well as mucoadhesion indicating, turbidity measurements and drug release studies after particle purification. The preparation was performed in the presence of insulin due to the formation of hydrogen bonds between poly(vinyl pyrrolidone) (PVP) and poly(acrylic acid) (PAA) or its conjugate poly(acrylic acid)-cysteine (PAA-Cys) with a molecular mass of 100 as well as 450 kDa. Stable suspensions, displaying nanoparticles with a mean particle size in the range of 200 nm as well as a negative zeta potential, were achieved with 100 kDa poly(acrylic acid) (PAA100) or poly(acrylic acid)-cysteine (PAA100-Cys). Turbidity measurements displayed a pH dependent interaction of nanoparticulate material and mucin leading to a greater and earlier interference at pH 3.9 compared to pH 7.4. Moreover a 1.2-fold increase of the absorbance of nanoparticle-mucin dispersions compared to mucin control was observed after 3 h. The introduced particulate drug delivery system might in conclusion display a sophisticated vehicle for the non-invasive delivery of insulin and other peptide drugs.