title: Direct measurement of interactions between stimulation-responsive drug delivery vehicles and artificial mucin layers by colloid probe atomic force microscopy.
abstract: A novel thermo- and pH-sensitive nanogel particle, which is a core-shell structured particle with a poly(N-isopropylacrylamide) (p(NIPAAm)) hydrogel core and a poly(ethylene glycol) monomethacrylate grafted poly(methacrylic acid) (p(MMA-g-EG)) shell, is of interest as a vehicle for the controlled release of peptide drugs. The interactions between such nanogel particles and artificial mucin layers during both approach and separation were successfully measured by using colloid probe atomic force microscopy (AFM) under various compression forces, scan velocities, and pH values. While the magnitudes of the compression forces and scan velocities did not affect the interactions during the approach process, the adhesive force during the separation process increased with these parameters. The pH values significantly influenced the interactions between the nanogel particles and a mucin layer. A large steric repulsive force and a long-range adhesive force were measured at neutral pH due to the swollen p(MMA-g-EG) shell. On the other hand, at low pH values, the steric repulsive force disappeared and a short-range adhesive force was detected, which resulted from the collapse of the shell layer. The nanogel particles possessed a pH response that was sufficient to protect the incorporated peptide drug under the harsh acidic conditions in the stomach and to effectively adhere to the mucin layer of the small intestine, where the pH is neutral. The relationships among the nanogel particle-mucin layer interactions, pH conditions, scan velocities, and compression forces were systemically investigated and discussed.
authors.affiliation: Institute of Symbiotic Science and Technology, Tokyo University of Agriculture and Technology, Koganei, Tokyo, Japan. motoyuki@cc.tuat.ac.jp
authors.forename: Motoyuki
authors.initials: M
authors.lastname: Iijima
authors.forename: Motoyasu
authors.initials: M
authors.lastname: Yoshimura
authors.forename: Tadashi
authors.initials: T
authors.lastname: Tsuchiya
authors.forename: Mayumi
authors.initials: M
authors.lastname: Tsukada
authors.forename: Hideki
authors.initials: H
authors.lastname: Ichikawa
authors.forename: Yoshinobu
authors.initials: Y
authors.lastname: Fukumori
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Kamiya
mesh_terms: D000178:Acrylamides / Q000737:chemistry; D000327:Adsorption; D003102:Colloids / Q000737:chemistry; D016503:Drug Delivery Systems; D006863:Hydrogen-Ion Concentration; D018625:Microscopy, Atomic Force; D008855:Microscopy, Electron, Scanning; D009077:Mucins / Q000737:chemistry* / Q000648:ultrastructure*; D000080385:Nanogels; D010316:Particle Size; D011092:Polyethylene Glycols / Q000737:chemistry; D011094:Polyethyleneimine / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D013499:Surface Properties
chemical_list: D000178:Acrylamides; D003102:Colloids; D009077:Mucins; D000080385:Nanogels; D011109:Polymethacrylic Acids; C413692:polyethylene glycol polyethyleneimine nanogel; D011092:Polyethylene Glycols; D011094:Polyethyleneimine; C067295:N-isopropylacrylamide