Mucoadhesion of latexes. I. Analytical methods and kinetic studies.

A Fourier transform infrared spectroscopy/attenuated total reflection technique for direct quantification of adsorbed poly(styrene) latexes on rat intestinal mucosa was developed for deposited latex amounts up to 1.5 g/m2. The method agreed well with another dosage assay of adsorbed particles by turbidimetry after denaturation of the mucus. Adsorption kinetics were made under static conditions at latex concentrations of 4 g/L in physiological saline. Ninety percent of equilibrium was reached after 10 min for a particle size of 230 nm, 20 min for a size of 320 nm, and 30 min for a size of 670 nm. The plateaus were between 0.6 and 0.9 g/m2 (adsorbed mass per apparent surface of mucosa). The first phase of the kinetics was theoretically approached by a diffusion model in the suspension medium. Mucosa from rat jejunum and ileum could be considered as a homogeneous biological model for latex adsorption.