title: Atomic force microscopy recognition of protein A on Staphylococcus aureus cell surfaces by labelling with IgG-Au conjugates.
abstract: The labelling of functional molecules on the surface of bacterial cells is one way to recognize the bacteria. In this work, we have developed a method for the selective labelling of protein A on the cell surfaces of Staphylococcus aureus by using nanosized immunogold conjugates as cell-surface markers for atomic force microscopy (AFM). The use of 30-nm size Au nanoparticles conjugated with immunoglobulin G (IgG) allowed the visualization, localization and distribution of protein A-IgG complexes on the surface of S. aureus. The selectivity of the labelling method was confirmed in mixtures of S. aureus with Bacillus licheniformis cells, which differed by size and shape and had no IgG receptors on the surface. A preferential binding of the IgG-Au conjugates to S. aureus was obtained. Thus, this novel approach allows the identification of protein A and other IgG receptor-bearing bacteria, which is useful for AFM indication of pathogenic microorganisms in poly-component associations.
authors.affiliation: Department of Microbiology, Orenburg State University, Pobedy Ave, 13, 460018, Orenburg, Russia.
authors.forename: Elena B
authors.initials: EB
authors.lastname: Tatlybaeva
authors.affiliation: Department of Biochemical Physics, Orenburg State University, Pobedy Ave, 13, 460018, Orenburg, Russia ; Institute of micro- and nanotechnologies of Orenburg State University, Pobedy Ave, 13, 460018, Orenburg, Russia.
authors.forename: Hike N
authors.initials: HN
authors.lastname: Nikiyan
authors.affiliation: Department of Biochemical Physics, Orenburg State University, Pobedy Ave, 13, 460018, Orenburg, Russia ; Institute of Cellular and Intracellular Symbiosis, RAS, Pionerskaya str., 11, 460000, Orenburg, Russia.
authors.forename: Alexey S
authors.initials: AS
authors.lastname: Vasilchenko
authors.affiliation: Department of Microbiology, Orenburg State University, Pobedy Ave, 13, 460018, Orenburg, Russia ; All-Russian Research Institute of Beef Cattle, RAA, 9 Yanvarja str, 29, 460000, Orenburg, Russia.
authors.forename: Dmitri G
authors.initials: DG
authors.lastname: Deryabin
keywords: IgG–gold nanoparticle conjugates; Staphylococcus aureus; atomic force microscopy; protein A