title: Encapsulation of Pancreatic Lipase in Hydrogel Beads with Self-Regulating Internal pH Microenvironments: Retention of Lipase Activity after Exposure to Gastric Conditions.
abstract: Oral delivery of lipase is important for individuals with exocrine pancreatic insufficiency; however, lipase loses activity when exposed to the highly acidic gastric environment. In this study, pancreatic lipase was encapsulated in hydrogel beads fabricated from alginate (gel former), calcium chloride (cross-linker), and magnesium hydroxide (buffer). Fluorescence confocal microscopy imaging was used to map the pH microclimate within the hydrogel beads under simulated gastrointestinal tract (GIT) conditions. The pH within buffer-free beads rapidly decreased when they moved from mouth (pH 6.3) to stomach (pH <4), leading to a loss of lipase activity in the small intestine. Conversely, the pH inside buffer-loaded beads remained close to neutral in the mouth (pH 7.33) and stomach (pH 7.39), leading to retention of lipase activity in the small intestine, as shown by pH-stat analysis of lipid digestion. The presence of the encapsulated buffer also reduced bead shrinkage under gastric conditions.
authors.affiliation: Department of Food Science, University of Massachusetts-Amherst , Amherst, Massachusetts 01003, United States.
authors.forename: Zipei
authors.initials: Z
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Food Science and Technology, Nanchang University , No. 8 235 Nanjing East Road, Nanchang 330047, Jiangxi, China.
authors.forename: Fang
authors.initials: F
authors.lastname: Chen
authors.affiliation: Department of Food Science, University of Massachusetts-Amherst , Amherst, Massachusetts 01003, United States.
authors.forename: Ruojie
authors.initials: R
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Food Science and Technology, Nanchang University , No. 8 235 Nanjing East Road, Nanchang 330047, Jiangxi, China.
authors.forename: Zeyuan
authors.initials: Z
authors.lastname: Deng
authors.affiliation: Department of Food Science, University of Massachusetts-Amherst , Amherst, Massachusetts 01003, United States.
authors.forename: David Julian
authors.identifier: http://orcid.org/0000-0002-9016-1291
authors.initials: DJ
authors.lastname: McClements
mesh_terms: D004795:Enzyme Stability; D041981:Gastrointestinal Tract / Q000378:metabolism; D006801:Humans; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008049:Lipase / Q000737:chemistry* / Q000378:metabolism; D008954:Models, Biological; D010179:Pancreas / Q000201:enzymology
chemical_list: D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D008049:Lipase
keywords: alginate; buffer; digestion; hydrogel beads; lipase