A new real-time method for investigation of affinity properties and binding kinetics of magnetic nanoparticles

作者：Orlov Alexey V; Nikitin Maxim P; Bragina Vera A; Znoyko Sergey L; Zaikina Marina N; Ksenevich Tatiana I; Gorshkov Boris G; Nikitin Petr I^*

来源：Journal of Magnetism and Magnetic Materials, 2015, 380: 231-235.

DOI：10.1016/j.jmmm.2014.10.019

• Magnetic nanoparticles
• Binding kinetics
• Affinity constant measurement
• Multivalency
• Label-free
• Biosensors
• Prostate-specific antigen
• Spectral correlation interferometry
• Surface plasmon resonance

A method for quantitative investigation of affinity constants of receptors immobilized on magnetic nanoparticles (MP) is developed based on spectral correlation interferometry (SCI). The SCI records with a picometer resolution the thickness changes of a layer of molecules or nanoparticles due to a biochemical reaction on a cover slip, averaged over the sensing area. The method is compatible with other types of sensing surfaces employed in biosensing. The measured values of kinetic association constants of magnetic nanoparticles are 4 orders of magnitude higher than those of molecular antibody association with antigen. The developed method also suggests highly sensitive detection of antigens in a wide dynamic range. The limit of detection of 92 pg/ml has been demonstrated for prostate-specific antigen (PSA) with 50-nm MP employed as labels, which produce 3-order amplification of the SCI signals. The calibration curve features high sensitivity (slope) of 3-fold signal raise per 10-fold increase of PSA concentration within 4-order dynamic range, which is an attractive compromise for precise quantitative and highly sensitive immunoassay. The proposed biosensing technique offers inexpensive disposable sensor chips of cover slips and represents an economically sound alternative to traditional immunoassays for disease diagnostics, detection of pathogens in food and environmental monitoring.

• 出版日期2015-4-15