title: The development of a silica nanoparticle-based label-free DNA biosensor.
abstract: A silica nanoparticle-based DNA biosensor capable of detecting Bacillus anthracis bacteria through the use of unlabelled ss-oligonucleotides has been developed. The biosensor makes use of the optical changes that accompany a nanoparticle-immobilized cationic conjugated polymer (polythiophene) interacting with single-stranded vs. hybridized oligonucleotides, where a fluorescence signal appears only when hybridized DNA is present (i.e. only when the ss-oligonucleotide interacting with the polymer has hybridized with its complement). In order to enhance the sensitivity of the biosensor, two different nanoparticle architectures were developed and used to elucidate how the presence of neighboring fluorophores on the nanoparticle surface affects Förster-resonant energy transfer (FRET) between the polythiophene/oligonucleotide complex (FRET donor) and the fluorophores (FRET acceptors). We demonstrate that the silica nanoparticle-based FRET platform lowers the limit of detection at least 10-fold in comparison to the polythiophene itself, and allows the detection of ∼2 × 10(-12) moles of ss-oligonucleotide in a 100 μL sample with a standard fluorimeter (i.e. has a limit of detection of ∼2 nM ssDNA). Such nanoparticle-based biosensor platforms are beneficial because of the robustness and stability inherent to their covalent assembly and they provide a valuable new tool that may allow for the sensitive, label-free detection (the target DNA that produces the fluorescence signal is unlabelled) without the use of polymerase chain reaction.
authors.affiliation: Steacie Institute for Molecular Sciences, National Research Council, 100 Sussex Drive, Ottawa, Ontario, Canada K1A 0R6. arnold.kell@nrc.ca
authors.forename: Arnold J
authors.initials: AJ
authors.lastname: Kell
authors.forename: Lilianne
authors.initials: L
authors.lastname: Pagé
authors.forename: Sophie
authors.initials: S
authors.lastname: Tan
authors.forename: Isabelle
authors.initials: I
authors.lastname: Charlebois
authors.forename: Maurice
authors.initials: M
authors.lastname: Boissinot
authors.forename: Mario
authors.initials: M
authors.lastname: Leclerc
authors.forename: Benoit
authors.initials: B
authors.lastname: Simard
mesh_terms: D001408:Bacillus anthracis / Q000235:genetics; D015374:Biosensing Techniques / Q000379:methods*; D004277:DNA, Single-Stranded / Q000032:analysis*; D031541:Fluorescence Resonance Energy Transfer; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D009693:Nucleic Acid Hybridization; D009841:Oligonucleotides / Q000032:analysis; D011108:Polymers / Q000737:chemistry; D011806:Quinolinium Compounds / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry*; D013876:Thiophenes / Q000737:chemistry
chemical_list: C481052:Alexa fluor 546; D004277:DNA, Single-Stranded; D009841:Oligonucleotides; D011108:Polymers; D011806:Quinolinium Compounds; D013876:Thiophenes; C066730:polythiophene; D012822:Silicon Dioxide