title: Dual on-off and off-on switchable oligoaziridine biosensor.
abstract: A water-soluble biocompatible aziridine-based biosensor with pendant anthracene units was synthesized by radicalar polymerization of N-substituted aziridines in supercritical carbon dioxide. The binding ability of the sensor towards a series of metal ions was examined by comparing the fluorescence intensities of the solutions before and after the addition of 100 equivalents of a solution of the metal ion chloride salt. A fast, simple and highly optical sensitive dual behavior, "off-on" and "on-off" response, was observed after the biosensor was exposed to the metal cations in aqueous solution. Zinc presented the highest fluorescence enhancement (turn-on) and copper presented the highest fluorescence quenching (turn-off). The response time was found to be instantaneous and the detection limit was achieved even in the presence of excess metal cation competitors. By using immunofluorescence microscopy it was also shown that oligoaziridine acts as an "on-off" probe through highly sensitive (detection limit of 1.6nM), selective and reversible binding to copper anions under physiologic conditions using living Human Fibroblast cells. The stoichiometry for the reaction of the biosensor with Cu(2+) was determined by a Job plot and indicates the formation of an oligoaziridine-Cu(2+) 1:2 adduct.
authors: REQUIMTE, Departamento de Química, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal.
authors: Vivek P
authors: VP
authors: Raje
authors: Patrícia I
authors: PI
authors: Morgado
authors: Maximiano P
authors: MP
authors: Ribeiro
authors: Ilídio J
authors: IJ
authors: Correia
authors: Vasco D B
authors: VD
authors: Bonifácio
authors: Paula S
authors: PS
authors: Branco
authors: Ana
authors: A
authors: Aguiar-Ricardo
mesh_terms: D001388:Aziridines / Q000737:chemistry* / Q000633:toxicity; D015374:Biosensing Techniques / Q000379:methods*; D002245:Carbon Dioxide / Q000737:chemistry; D002412:Cations / Q000032:analysis; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D003300:Copper / Q000032:analysis*; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects; D006801:Humans; D057230:Limit of Detection; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence / Q000379:methods; D015032:Zinc / Q000032:analysis
chemical_list: D001388:Aziridines; D002412:Cations; D002245:Carbon Dioxide; C033132:aziridine; D003300:Copper; D015032:Zinc