title: Identification of molecular-mimicry-based ligands for cholera diagnostics using magnetic relaxation.
abstract: When covalently bound to an appropriate ligand, iron oxide nanoparticles can bind to a specific target of interest. This interaction can be detected through changes in the solution's spin-spin relaxation times (T2) via magnetic relaxation measurements. In this report, a strategy of molecular mimicry was used in order to identify targeting ligands that bind to the cholera toxin B subunit (CTB). The cellular CTB-receptor, ganglioside GM1, contains a pentasaccharide moiety consisting in part of galactose and glucose units. We therefore predicted that CTB would recognize carbohydrate-conjugated iron oxide nanoparticles as GM1 mimics, thus producing a detectable change in the T2 relaxation times. Magnetic relaxation experiments demonstrated that CTB interacted with the galactose-conjugated nanoparticles. This interaction was confirmed via surface plasmon resonance studies using either the free or nanoparticle-conjugated galactose molecule. The galactose-conjugated nanoparticles were then used as CTB sensors achieving a detection limit of 40 pM. Via magnetic relaxation studies, we found that CTB also interacted with dextran-coated nanoparticles, and surface plasmon resonance studies also confirmed this interaction. Additional experiments demonstrated that the dextran-coated nanoparticle can also be used as CTB sensors and that dextran can prevent the internalization of CTB into GM1-expressing cells. Our work indicates that magnetic nanoparticle conjugates and magnetic relaxation detection can be used as a simple and fast method to identify targeting ligands via molecular mimicry. Furthermore, our results show that the dextran-coated nanoparticles represent a low-cost approach for CTB detection.
authors.affiliation: Nanoscience Technology Center, University of Central Florida, 12424 Research Parkway, Suite 400, Orlando, Florida 32826, United States.
authors.forename: Charalambos
authors.initials: C
authors.lastname: Kaittanis
authors.forename: Tuhina
authors.initials: T
authors.lastname: Banerjee
authors.forename: Santimukul
authors.initials: S
authors.lastname: Santra
authors.forename: Oscar J
authors.initials: OJ
authors.lastname: Santiesteban
authors.forename: Ken
authors.initials: K
authors.lastname: Teter
authors.forename: J Manuel
authors.initials: JM
authors.lastname: Perez
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000737:chemistry; D002522:Chlorocebus aethiops; D002771:Cholera / Q000175:diagnosis*; D002772:Cholera Toxin / Q000737:chemistry; D003911:Dextrans / Q000737:chemistry; D005290:Ferric Compounds / Q000737:chemistry; D005677:G(M1) Ganglioside / Q000737:chemistry; D005690:Galactose / Q000737:chemistry; D008024:Ligands; D008280:Magnetics; D008968:Molecular Conformation; D018716:Molecular Mimicry; D053758:Nanoparticles / Q000737:chemistry; D020349:Surface Plasmon Resonance; D014709:Vero Cells
chemical_list: D003911:Dextrans; D005290:Ferric Compounds; D008024:Ligands; C000499:ferric oxide; D005677:G(M1) Ganglioside; D002772:Cholera Toxin; D005690:Galactose