title: Versatile SPR aptasensor for detection of lysozyme dimer in oligomeric and aggregated mixtures.
abstract: A Surface Plasmon Resonance (SPR) sensor for the quantitation of lysozyme dimer in monomer-dimer mixtures, reaching a detection limit of 1.4nM dimer, has been developed. The sensor is based on an aptamer which, although developed for the monomeric form, binds also the dimeric form but with a strikingly different kinetics. The aptasensor was calibrated using a dimer obtained by cross-linking. Sensorgrams acquired with the aptasensor in monomer-dimer mixtures were analysed using Principal Components Analysis and Multiple Regression to establish correlations with the dimer content in the mixtures. The method allows the detection of 0.1-1% dimer in monomer solutions without any separation. As an application, the aptasensor was used to qualitatively observe the initial stages of aggregation of lysozyme solutions at 60°C and pH 2, through the variations in lysozyme dimer amounts. Several other methods were used to characterize the lysozyme dimer obtained by cross-linking and confirm the SPR results. This work highlights the versatility of the aptasensor, which can be used, by simply tuning the experimental conditions, for the sensitive detection of either the monomer or the dimer and for the observation of the aggregation process of lysozyme.
authors.affiliation: International Centre of Biodynamics, 1 B Intrarea Portocalelor, 060101 Bucharest, Romania. Electronic address: avasilescu@biodyn.ro.
authors.forename: Alina
authors.initials: A
authors.lastname: Vasilescu
authors.affiliation: Institute of Biology of the Romanian Academy, 296 Splaiul Independentei, 060031 Bucharest, Romania.
authors.forename: Cristina
authors.initials: C
authors.lastname: Purcarea
authors.affiliation: Institute of Biology of the Romanian Academy, 296 Splaiul Independentei, 060031 Bucharest, Romania.
authors.forename: Elena
authors.initials: E
authors.lastname: Popa
authors.affiliation: Institute of Biology of the Romanian Academy, 296 Splaiul Independentei, 060031 Bucharest, Romania.
authors.forename: Medana
authors.initials: M
authors.lastname: Zamfir
authors.affiliation: University of Bucharest, Faculty of Chemistry, Department of Analytical Chemistry, 4-12 Blvd. Regina Elisabeta, 030018 Bucharest, Romania.
authors.forename: Iuliana
authors.initials: I
authors.lastname: Mihai
authors.affiliation: National Institute for Research and Development in Biological Sciences, Bioanalysis Center, 296 Splaiul Independentei, Bucharest, Romania.
authors.forename: Simona
authors.initials: S
authors.lastname: Litescu
authors.affiliation: International Centre of Biodynamics, 1 B Intrarea Portocalelor, 060101 Bucharest, Romania.
authors.forename: Sorin
authors.initials: S
authors.lastname: David
authors.affiliation: International Centre of Biodynamics, 1 B Intrarea Portocalelor, 060101 Bucharest, Romania.
authors.forename: Szilveszter
authors.initials: S
authors.lastname: Gaspar
authors.affiliation: International Centre of Biodynamics, 1 B Intrarea Portocalelor, 060101 Bucharest, Romania.
authors.forename: Mihaela
authors.initials: M
authors.lastname: Gheorghiu
authors.affiliation: BAE: Biocapteurs-Analyses-Environnement, Universite de Perpignan Via Domitia, 52 Avenue Paul Alduy, Perpignan Cedex 66860, France. Electronic address: jlmarty@univ-perp.fr.
authors.lastname: Jean-Louis Marty
mesh_terms: D000818:Animals; D052157:Aptamers, Nucleotide / Q000737:chemistry*; D002645:Chickens; D057230:Limit of Detection; D009113:Muramidase / Q000032:analysis*; D066329:Protein Aggregates; D055503:Protein Multimerization; D020349:Surface Plasmon Resonance / Q000379:methods*
chemical_list: D052157:Aptamers, Nucleotide; D066329:Protein Aggregates; C421864:hen egg lysozyme; D009113:Muramidase
keywords: Aptamer-based sensor; Lysozyme dimer; Soluble oligomers; Surface plasmon resonance