title: G-quadruplex-forming oligonucleotide conjugated to magnetic nanoparticles: synthesis, characterization, and enzymatic stability assays.
abstract: In the present work, we report the conjugation of superparamagnetic nanoparticles to a fluorescently labeled oligodeoxyribonucleotide (ODN) able to fold into stable unimolecular guanine quadruple helix under proper ion conditions by means of its thrombin-binding aptamer (TBA) sequence. The novel modified ODN, which contained a fluorescent dU(Py) unit at 3'-end and a 12-amino-dodecyl spacer (C(12)-NH(2)) at 5' terminus, was characterized by ESI-MS and optical spectroscopy (UV, CD, fluorescence), and analyzed by RP-HPLC chromatography and electrophoresis. From CD and fluorescence experiments, we verified that dU(Py) and C(12)-NH(2) incorporation does not interfere with the conformational stability of the G-quadruplex. Subsequently, the conjugation of the pyrene-labeled ODN with the magnetite particles was performed, and the ODN-conjugated nanoparticles were studied through optical spectroscopy (UV, CD, fluorescence) and by enzymatic and chemical assays. We found that the nanoparticles enhanced the stability of the TBA ODN to enzymatic degradation. Finally, we evaluated the amount of the TBA-conjugated nanoparticles immobilized on a magnetic separator in view of the potential use of the nanosystem for the magnetic capture of thrombin from complex mixtures.
authors.affiliation: Dipartimento di Chimica delle Sostanze Naturali, Università di Napoli Federico II, Via D. Montesano 49, 80131 Napoli, Italy. domymusu@alice.it
authors.forename: Domenica
authors.initials: D
authors.lastname: Musumeci
authors.forename: Giorgia
authors.initials: G
authors.lastname: Oliviero
authors.forename: Giovanni N
authors.initials: GN
authors.lastname: Roviello
authors.forename: Enrico M
authors.initials: EM
authors.lastname: Bucci
authors.forename: Gennaro
authors.initials: G
authors.lastname: Piccialli
mesh_terms: D002851:Chromatography, High Pressure Liquid; D004795:Enzyme Stability; D054856:G-Quadruplexes; D008280:Magnetics; D053758:Nanoparticles; D009841:Oligonucleotides / Q000737:chemistry*; D013057:Spectrum Analysis / Q000379:methods
chemical_list: D009841:Oligonucleotides