title: Small mesh size hydrogel for functional photocontrol of encapsulated enzymes and small probe molecules.
abstract: Previously, we developed the "protein activation and release from cage by external light" (PARCEL) method for controlling the function of proteins by encapsulating them in a photodegradable hydrogel and subsequently releasing them by ultraviolet (UV) irradiation of the gel. However, controlling small proteins is difficult because small proteins can leak from the gap (ca. 12.4 nm) of the mesh structure of the hydrogel without irradiation. Here, we developed a photodegradable gel with a smaller mesh size (~3.6 nm) and used the new gel to control the function of three small enzymes (trypsin, chymotrypsin, and elastase) and several small nonprotein molecules. The new gel showed reduced leakage of the proteins without irradiation, and tryptic activity increased approximately 78-fold upon irradiation of gel-encapsulated trypsin. The new gel also permitted encapsulation and release of 4',6-diamidino-2-phenylindole (DAPI, molecular weight 277), a small DNA-specific fluorescent probe. After irradiation to the gel-encapsulated DAPI and subsequent addition of DNA, strong fluorescence of the DAPI-DNA complex was observed. Our results indicate that reducing the gel mesh size from 12.4 to 3.6 nm should allow the encapsulation of various proteins and small molecules in an inactive state and their subsequent light-induced release. We expect this method to be useful in preparation of photoactivated biosensors, drug delivery systems, and catalysis.
authors.affiliation: Graduate School of Pharmaceutical Sciences and Global COE Program, The University of Tokyo, 7-3-1 Hongo, Tokyo 113-0033, Japan.
authors.forename: Shuhei
authors.initials: S
authors.lastname: Murayama
authors.forename: Fumi
authors.initials: F
authors.lastname: Ishizuka
authors.forename: Kaihei
authors.initials: K
authors.lastname: Takagi
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Inoda
authors.forename: Akira
authors.initials: A
authors.lastname: Sano
authors.forename: Tomofumi
authors.initials: T
authors.lastname: Santa
authors.forename: Masaru
authors.initials: M
authors.lastname: Kato
mesh_terms: D002918:Chymotrypsin / Q000378:metabolism*; D004247:DNA / Q000737:chemistry / Q000378:metabolism; D004800:Enzymes, Immobilized / Q000378:metabolism; D005456:Fluorescent Dyes / Q000737:chemistry / Q000378:metabolism; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate / Q000737:chemistry*; D007211:Indoles / Q000737:chemistry / Q000378:metabolism; D010196:Pancreatic Elastase / Q000378:metabolism*; D010316:Particle Size; D010782:Photolysis; D014357:Trypsin / Q000378:metabolism*; D014466:Ultraviolet Rays
chemical_list: D004800:Enzymes, Immobilized; D005456:Fluorescent Dyes; D007211:Indoles; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; C007293:DAPI; D004247:DNA; D002918:Chymotrypsin; D010196:Pancreatic Elastase; D014357:Trypsin