title: Characterizing permeability and stability of microcapsules for controlled drug delivery by dynamic NMR microscopy.
abstract: Microscopic capsules made from polysaccharides are used as carriers for drugs and food additives. Here, we use NMR microscopy to assess the permeability of capsule membranes and their stability under different environmental conditions. The results allow us to determine the suitability of different capsules for controlled drug delivery. As a measure of the membrane permeability, we monitor the diffusion of paramagnetic molecules into the microcapsules by dynamic NMR microimaging. We obtained the diffusion coefficients of the probe molecules in the membranes and in the capsule core by comparing the measured time dependent concentration maps with numerical solutions of the diffusion equation. The results reveal that external coatings strongly decrease the permeability of the capsules. In addition, we also visualized that the capsules are stable under gastric conditions but dissolve under simulated colonic conditions, as required for targeted drug delivery. Depending on the capsule, the timescales for these processes range from 1 to 28 h.
authors: Experimental Physics III, TU Dortmund University, 44227 Dortmund, Germany. stefan.henning@tu-dortmund.de
authors: Stefan
authors: S
authors: Henning
authors: Daniel
authors: D
authors: Edelhoff
authors: Benedikt
authors: B
authors: Ernst
authors: Sabine
authors: S
authors: Leick
authors: Heinz
authors: H
authors: Rehage
authors: Dieter
authors: D
authors: Suter
mesh_terms: D000465:Algorithms; D000872:Anthocyanins / Q000737:chemistry; D002214:Capsules / Q000032:analysis*; D003106:Colon / Q000737:chemistry / Q000378:metabolism; D003287:Contrast Media; D003692:Delayed-Action Preparations; D004058:Diffusion; D004339:Drug Compounding; D016503:Drug Delivery Systems; D004355:Drug Stability; D005079:Excipients; D005753:Gastric Mucosa / Q000378:metabolism; D007421:Intestine, Small / Q000737:chemistry / Q000378:metabolism; D008279:Magnetic Resonance Imaging; D008567:Membranes, Artificial; D008853:Microscopy; D010316:Particle Size; D010368:Pectins / Q000737:chemistry; D010539:Permeability; D012116:Resins, Plant; D012995:Solubility; D013270:Stomach / Q000737:chemistry
chemical_list: D000872:Anthocyanins; D002214:Capsules; D003287:Contrast Media; D003692:Delayed-Action Preparations; D005079:Excipients; D008567:Membranes, Artificial; D012116:Resins, Plant; C003934:shellac; D010368:Pectins