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.
Institute of Pharmaceutical Technology and Biopharmaceutics, The University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria.
B
B
Ertl
F
F
Heigl
M
M
Wirth
F
F
Gabor
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