title: Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry for quantitation and molecular stability assessment of insulin entrapped within PLGA nanoparticles.
abstract: Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was evaluated for both qualitative and quantitative analysis of insulin entrapped within poly(D,L-lactic-co-glycolic acid) nanoparticles. Quantitation was performed by adding an internal standard (arg-insulin) to defined and unknown sample solutions, in order to reduce point-to-point and sample-to-sample variability. The ratio of the peak height of insulin to the peak height of arg-insulin was plotted against the insulin concentration. In this way, an excellent linear relationship was found (R2 > 0.99). This method of quantitation was compared with classical UV spectroscopy and reverse-phase high-performance liquid chromatography measurements. All methods provided close final drug loading values for the insulin-loaded nanoparticle batches tested. Additionally, with respect to molecular stability, covalent insulin dimers were found only at trace levels in those nanoparticles. Compared with other methods, MALDI-TOF MS is a valuable tool for the characterization of proteins from nanoparticles, because no extensive extraction and complex sampling procedures are required.
authors.affiliation: School of Pharmacy, University of Geneva, Quai Ernest-Ansermet 30, 1211 Geneva 4, Switzerland.
authors.forename: Ugo
authors.initials: U
authors.lastname: Bilati
authors.forename: Carla
authors.initials: C
authors.lastname: Pasquarello
authors.forename: Garry L
authors.initials: GL
authors.lastname: Corthals
authors.forename: Denis F
authors.initials: DF
authors.lastname: Hochstrasser
authors.forename: Eric
authors.initials: E
authors.lastname: Allémann
authors.forename: Eric
authors.initials: E
authors.lastname: Doelker
mesh_terms: D000818:Animals; D004337:Drug Carriers / Q000032:analysis; D004355:Drug Stability; D005069:Evaluation Studies as Topic; D007328:Insulin / Q000032:analysis*; D019344:Lactic Acid / Q000032:analysis*; D049329:Nanostructures / Q000032:analysis*; D011100:Polyglycolic Acid / Q000032:analysis*; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011108:Polymers / Q000032:analysis*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*; D013552:Swine
chemical_list: D004337:Drug Carriers; D007328:Insulin; D011108:Polymers; D000077182:Polylactic Acid-Polyglycolic Acid Copolymer; D011100:Polyglycolic Acid; D019344:Lactic Acid