title: Protein adsorption and displacement at lipid layers determined by total internal reflection fluorescence (TIRF).
abstract: In many drug delivery systems such as liposomes, the adsorption of interstitial proteins upon administration can have a huge effect on the elimination, release, and stability of the delivery system. For example, it is assumed that PEGylated liposomes prevent the adsorption of opsonins and thereby prolong the circulation time in vivo, and EMEA guidelines recommend that more than 80% of the protein antigen is adsorbed in the formulation of adjuvant systems. However, few methods exist to elucidate this protein adsorption. The present study indicates that total internal reflection fluorescence (TIRF) is a possible method to examine the adsorption and exchange of proteins at lipid surfaces. In the TIRF set-up, a lipid layer can be formed [exemplified with dimethyldioctadecylammonium bromide (DDA) and D-(+)-trehalose 6,6'-dibehenate (TDB)] whereafter protein (i.e., ovalbumin or an antigen, Ag85B-ESAT-6) is adsorbed, and these proteins can subsequently be displaced by the abundant interstitial protein (i.e., serum albumin).
authors.affiliation: Department of Pharmaceutics and Analytical Chemistry, The Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, Copenhagen, Denmark. lej@farma.ku.dk
authors.forename: Lene
authors.initials: L
authors.lastname: Jorgensen
authors.forename: Grith Krøyer
authors.initials: GK
authors.lastname: Wood
authors.forename: Ida
authors.initials: I
authors.lastname: Rosenkrands
authors.forename: Charlotte
authors.initials: C
authors.lastname: Petersen
authors.forename: Dennis
authors.initials: D
authors.lastname: Christensen
mesh_terms: D000276:Adjuvants, Immunologic; D000327:Adsorption; D016503:Drug Delivery Systems; D005453:Fluorescence; D006017:Glycolipids; D008055:Lipids; D008081:Liposomes; D011506:Proteins / Q000502:physiology*; D000644:Quaternary Ammonium Compounds; D012709:Serum Albumin; D014199:Trehalose
chemical_list: D000276:Adjuvants, Immunologic; D006017:Glycolipids; D008055:Lipids; D008081:Liposomes; D011506:Proteins; D000644:Quaternary Ammonium Compounds; D012709:Serum Albumin; C507803:trehalose 6,6'-dibehenate; C015831:dimethyldioctadecylammonium; D014199:Trehalose