title: Evaluation of calibration-free concentration analysis provided by Biacore™ systems.
abstract: Surface Plasmon Resonance biosensors measure the interaction between a molecule in solution and its interaction partner attached to a sensor surface. Under certain conditions, the observed binding rate can be used directly to obtain the concentration of the molecule in solution, without the use of any standard. This type of assay is referred to as Calibration Free Concentration Analysis, CFCA. By examining experimental conditions, including immobilization levels and temperature, for a range of analytes, and by using global analysis of several sample dilutions, conditions that gave the most robust results were identified. These conditions provided the concentration values that were on average ∼15% lower than those obtained using other methods. The accuracy of the concentration determined may be related to how the analyte is distributed in the dextran matrix and to its distance from the gold surface, and may thereby depend on the conversion of the SPR signal to mass. A good precision of CFCA, ∼8% (n = 21), was demonstrated when this method was used to efficiently guide purification procedures of Interferon α-2a. In this paper, the theory behind CFCA and the future developments, as well as the application of CFCA for absolute and relative concentration measurements (including the assessment of the potency of a biotherapeutic medicine) are discussed, and new evaluation tools that broaden the range of applications, are introduced.
authors.affiliation: GE Healthcare Bio-Sciences, Uppsala, Sweden. Electronic address: ewa.pol@ge.com.
authors.forename: Ewa
authors.initials: E
authors.lastname: Pol
authors.affiliation: GE Healthcare Bio-Sciences, Uppsala, Sweden.
authors.forename: Håkan
authors.initials: H
authors.lastname: Roos
authors.affiliation: GE Healthcare Bio-Sciences, Uppsala, Sweden.
authors.forename: Francis
authors.initials: F
authors.lastname: Markey
authors.affiliation: GE Healthcare Bio-Sciences, Uppsala, Sweden.
authors.forename: Fredrik
authors.initials: F
authors.lastname: Elwinger
authors.affiliation: Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Alan
authors.initials: A
authors.lastname: Shaw
authors.affiliation: GE Healthcare Bio-Sciences, Uppsala, Sweden.
authors.forename: Robert
authors.initials: R
authors.lastname: Karlsson
mesh_terms: D002138:Calibration; D006801:Humans; D016898:Interferon-alpha / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D008956:Models, Chemical; D012984:Software; D020349:Surface Plasmon Resonance / Q000379:methods* / Q000592:standards
chemical_list: D016898:Interferon-alpha
keywords: Biacore; Biosimilar; CFCA; SPR