title: Femtomolar detection of autoantibodies by magnetic relaxation nanosensors.
abstract: The development of nanosystems applied to rapid and sensitive measurement of biomarkers in fluid samples is a current major goal in diagnostic biomedicine. In this article, we report the accurate and reliable detection of anti-HSA (human serum albumin) antibodies by protein-functionalized magnetic nanospherical probes due to the reversible alteration of their microaggregation state induced by protein antibody-specific interaction, sensed as changes in the T(2) relaxation time of surrounding water molecules. Once the optimal parameters were adjusted, the method proved to be very sensitive, providing concentration- and time-dependent responses. Furthermore, we demonstrate that the developed immunoassay is able to quantitatively determine the biomarker concentration from T(2) linear correlation, thereby supplying a rapid, yet accurate, assay with sensitivity in the femtomolar range. The high susceptibility and stability of these magnetic nanoparticles, as well as their accessible synthetic preparation, make these nanosensors a promising new tool for versatile and effective medical diagnostics.
authors.affiliation: Dipartimento di Biotecnologie e Bioscienze, Università di Milano-Bicocca, 20126 Milano, Italy.
authors.forename: Miriam
authors.initials: M
authors.lastname: Colombo
authors.forename: Silvia
authors.initials: S
authors.lastname: Ronchi
authors.forename: Diego
authors.initials: D
authors.lastname: Monti
authors.forename: Fabio
authors.initials: F
authors.lastname: Corsi
authors.forename: Emilio
authors.initials: E
authors.lastname: Trabucchi
authors.forename: Davide
authors.initials: D
authors.lastname: Prosperi
mesh_terms: D001323:Autoantibodies / Q000032:analysis* / Q000276:immunology; D006801:Humans; D008280:Magnetics; D046529:Microscopy, Electron, Transmission; D015336:Molecular Probe Techniques; D053758:Nanoparticles / Q000032:analysis* / Q000737:chemistry / Q000648:ultrastructure; D012709:Serum Albumin / Q000276:immunology; D012822:Silicon Dioxide
chemical_list: D001323:Autoantibodies; D012709:Serum Albumin; D012822:Silicon Dioxide