A fluorescent polymeric hybridization transducer supported on magnetic microbeads was investigated for the
rapid, ultrasensitive, and sequence-specific detection of
DNA. We show that the polymer derivative can be used
to detect target DNA directly on magnetic particles by
preparing “target-ready” microbeads grafted with the
polymer and suitable DNA probes. A detection limit of
∼200 target copies in a probed volume of 150 μL (1.4
copies/μL) was obtained for a DNA sequence specific to
Candida albicans This detection scheme does not
require the release of the hybridized target DNA prior to
its detection or the labeling or amplification of the nucleic
acids. Furthermore, we show that the fluorescence from
these biosensing magnetic beads can be read while
magnetically confined in a small volume by a microelectromagnetic trap, which offers the possibility of performing
both the preconcentration and detection steps simultaneously on the same support. The combination of the
fluorescent polymer biosensor with magnetic particle-assisted DNA preconcentration extends the application
of this ultrasensitive biosensor to biological samples with
complex matrixes and to integrated lab-on-a-chip platforms, where it could be used for fast multitarget DNA
detection in point-of-care diagnostics and field analysis.
Self-assembled molecular structures immobilized on solid substrates and composed of fluorophore-tagged oligonucleotide probes and an optical polymeric transducer were investigated for the trace level detection of DNA target molecules. Rapid and efficient energy transfer between the polymeric transducer and fluorophores within the molecular aggregates leads to a massive intrinsic amplification of the fluorescence signal and to the label-free detection of as little as 300 DNA molecules, with the specificity required for the detection of single-nucleotide mismatches. This capacity for attomolar detection levels while the sensing structures are attached onto solid supports could lead to the development of biochip platforms for fast and simple PCR-free multitarget DNA detection.
By combining an appropriate DNA aptamer with a cationic polythiophene optical transducer, human thrombin can be specifically detected on microarrays in the attomole range in less than one hour without any tagging of the target. The system can be modified and utilized as a probe for the detection of various proteins or other biomolecules. This work opens new interesting possibilities for simple and rapid multiparametric analysis in genomics and proteomics.
Laser-enhanced ionization was investigated as a detection technique for trace elemental analysis of solid samples by laser ablation. Laser ablation of aluminum samples was performed in an ablation cell, and the ablated material was carried by a flow of gas to a miniature LEI flame where Pb was detected. This decoupling of ablation cell and detector allowed the independent optimization of vaporization and detection processes. We have investigated the different excitation schemes for Pb and uncovered five new LEI-active transitions in the visible range. We have demonstrated that the use of an argon-oxygen/acetylene flame sheathed with argon resulted in the elimination of background interference from the two-photon ionization of nitric oxide. We have shown that the use of helium as a carrier gas results in a higher ablation yield and lower pulse-to-pulse variations in LEI signal and in better analytical figures of merit. We have characterized the performance of the technique in terms of detection limits and dynamic range, and we have obtained a detection limit of 60 ng/g for the determination of Pb in high purity aluminum.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.