Lectin-mediated bioadhesion: preparation, stability and caco-2 binding of wheat germ agglutinin-functionalized Poly(D,L-lactic-co-glycolic acid)-microspheres.
To take advantage of the cytoadhesive characteristics of Wheat germ agglutinin (WGA) for improved particulate drug delivery, the interaction between WGA-grafted poly(D,L-lactic-co-glycolic acid)-microspheres and Caco-2 monolayers was investigated using bovine serum albumin (BSA) or glycine coated microspheres as a control. Covalent immobilization of WGA by the carbodiimide/N-hydroxysuccinimide-method on 4 microm microspheres yielded a surface density of 9.67+/-1.21x10(6) molecules/particle, whereas 0.22+/-0.04x10(6) WGA-molecules were bound by physical adsorption. After storage for 21 days in HEPES-buffer and treatment of the particles with 5 M urea, 86% of covalently linked lectin was still attached to the particles. At 4 degrees C the Caco-2 binding rate of both, WGA- and BSA-modified particles increased with addition of increasing numbers of particles until saturation was reached at 38150+/-1740 (WGA) or 12066+/-1195 (BSA) microspheres bound/mm(2) Caco-2 monolayer. Inhibition of Caco-2 binding of WGA-functionalized microspheres by chitotriose indicated for specificity of the interaction. As observed by confocal laser scanning microscopy, the fluorescein-loading of the particles was accumulated intracellularly after incubation of Caco-2 monolayers with WGA-modified microspheres contrary to glycine-grafted microspheres. Additionally, in case of WGA-functionalized microspheres the amount of cell associated fluorescein was 200-fold higher than that of the free solution. In conclusion, WGA-modified microspheres are expected to enhance intestinal transport of incorporated drugs due to cytoadhesion provided by the lectin coating.
Ertl
B
B
Institute of Pharmaceutical Technology and Biopharmaceutics, The University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria.
Heigl
F
F
Wirth
M
M
Gabor
F
F
D000818:Animals; D018938:Caco-2 Cells / Q000378:metabolism*; D002417:Cattle; D004337:Drug Carriers; D006801:Humans; D019344:Lactic Acid / Q000138:chemical synthesis / Q000493:pharmacokinetics*; D037102:Lectins / Q000138:chemical synthesis / Q000493:pharmacokinetics; D008863:Microspheres; D011100:Polyglycolic Acid / Q000138:chemical synthesis / Q000493:pharmacokinetics*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers / Q000138:chemical synthesis / Q000493:pharmacokinetics*; D014909:Wheat Germ Agglutinins / Q000138:chemical synthesis / Q000493:pharmacokinetics*
D004337:Drug Carriers; D037102:Lectins; D011108:Polymers; D014909:Wheat Germ Agglutinins; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid