title: Controlled loading of oligodeoxyribonucleotide monolayers onto unoxidized crystalline silicon; fluorescence-based determination of the surface coverage and of the hybridization efficiency; parallel imaging of the process by Atomic Force Microscopy.
abstract: Unoxidized crystalline silicon, characterized by high purity, high homogeneity, sturdiness and an atomically flat surface, offers many advantages for the construction of electronic miniaturized biosensor arrays upon attachment of biomolecules (DNA, proteins or small organic compounds). This allows to study the incidence of molecular interactions through the simultaneous analysis, within a single experiment, of a number of samples containing small quantities of potential targets, in the presence of thousands of variables. A simple, accurate and robust methodology was established and is here presented, for the assembling of DNA sensors on the unoxidized, crystalline Si(100) surface, by loading controlled amounts of a monolayer DNA-probe through a two-step procedure. At first a monolayer of a spacer molecule, such as 10-undecynoic acid, was deposited, under optimized conditions, via controlled cathodic electrografting, then a synthetic DNA-probe was anchored to it, through amidation in aqueous solution. The surface coverage of several DNA-probes and the control of their efficiency in recognizing a complementary target-DNA upon hybridization were evaluated by fluorescence measurements. The whole process was also monitored in parallel by Atomic Force Microscopy (AFM).
authors.affiliation: Istituto di Struttura della Materia, CNR, Via Salaria Km 29,300, 00016 Monterotondo Stazione, Rome, Italy.
authors.forename: Fabrizio
authors.initials: F
authors.lastname: Cattaruzza
authors.forename: Antonio
authors.initials: A
authors.lastname: Cricenti
authors.forename: Alberto
authors.initials: A
authors.lastname: Flamini
authors.forename: Marco
authors.initials: M
authors.lastname: Girasole
authors.forename: Giovanni
authors.initials: G
authors.lastname: Longo
authors.forename: Tommaso
authors.initials: T
authors.lastname: Prosperi
authors.forename: Giuseppina
authors.initials: G
authors.lastname: Andreano
authors.forename: Luciano
authors.initials: L
authors.lastname: Cellai
authors.forename: Emanuele
authors.initials: E
authors.lastname: Chirivino
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D015342:DNA Probes / Q000737:chemistry* / Q000648:ultrastructure; D005231:Fatty Acids, Unsaturated / Q000737:chemistry; D005453:Fluorescence; D005456:Fluorescent Dyes / Q000737:chemistry*; D018625:Microscopy, Atomic Force; D009693:Nucleic Acid Hybridization / Q000379:methods*; D015345:Oligonucleotide Probes / Q000737:chemistry* / Q000648:ultrastructure; D012825:Silicon / Q000737:chemistry*
chemical_list: D015342:DNA Probes; D005231:Fatty Acids, Unsaturated; D005456:Fluorescent Dyes; D015345:Oligonucleotide Probes; C048289:10-undecynoic acid; D012825:Silicon