title: Biphasic release of protein from polyethylene glycol and polyethylene glycol/modified dextran microspheres.
abstract: Dextrans show great promise for delivery of therapeutic agents. Dextran acetates (DAs) were synthesized with increasing degrees of substitution (DA1 < DA2 < DA3) by the reaction of the polysaccharide dextran (70 kDa) with acetic anhydride. A series of polyethylene glycol (PEG)/DA microspheres were prepared and tested with bovine serum albumin (BSA) functioning as a model protein. Particle size (0.74-0.85 μm) and encapsulation efficiency (56-70%) increased with the degree of substitution along with a slower release rate of protein from PEG/DA microspheres. Time to release 90% of protein rose from 31 to 118 min. Percentage of BSA released from PEG and PEG/DA3 microspheres with time (min) was modeled mathematically [Y(PEG) = 100(1 - e(-0.12t)); Y(PEG/DA3) = 100(1 - e(-0.024t))] to predict cumulative delivery from mixtures in vitro over a period of hours when constrained to a target level at 30 min. The system is examined for potential application in thrombolytic therapy.
authors: School of Chemical, Biological and Materials Engineering, University of Oklahoma, Norman, Oklahoma 73019, USA.
authors: Hoai X
authors: HX
authors: Nguyen
authors: Edgar A
authors: EA
authors: O'Rear
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry; D002417:Cattle; D003692:Delayed-Action Preparations / Q000008:administration & dosage; D003911:Dextrans / Q000737:chemistry*; D016503:Drug Delivery Systems; D008422:Materials Testing; D008855:Microscopy, Electron, Scanning; D008863:Microspheres; D010316:Particle Size; D011092:Polyethylene Glycols / Q000737:chemistry*; D011506:Proteins / Q000008:administration & dosage*; D012710:Serum Albumin, Bovine / Q000008:administration & dosage
chemical_list: D001672:Biocompatible Materials; D003692:Delayed-Action Preparations; D003911:Dextrans; D011506:Proteins; D012710:Serum Albumin, Bovine; D011092:Polyethylene Glycols
keywords: biphasic release of protein; dextran acetate; microspheres; polyethylene glycol; reocclusion