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Publications (2)9.93 Total impact

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    ABSTRACT: Based on the high efficiency of fluorescence quenching and the different affinities of water-soluble carbon nanoparticles (CNPs) towards single-stranded DNA (ssDNA) and double-stranded DNA/RNA hybrid, a novel, rapid and cost-effective assay for detection of microRNA and nuclease activity was developed. The fluorescein-labeled ssDNA probe (FAM-P) could be adsorbed on the surface of CNPs through π-π stacking interaction giving rise to fluorescence quenching. By introduction of microRNA complementary to the DNA probe, the double-stranded DNA/miRNA hybrid could be formed and released from the surface of CNPs resulting in the fluorescence recovery. Thus, microRNA was successfully detected in homogenous fashion without any amplification or enzyme-involving reactions. Moreover, we demonstrated that the nuclease activities of RNase H and DNase I could also be sensitively monitored by using CNPs based on the fluorescence changing of the DNA probe. So, the CNPs provide an excellent homogeneous sensing platform for studying molecular diagnosis and therapeutics.
    The Analyst 07/2012; 137(16):3667-72. · 4.23 Impact Factor
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    ABSTRACT: Ligase chain reaction (LCR) offers a simple and robust alternative platform for nucleic acid amplification, but its application has been limited because the LCR products are mostly detected by gel electrophoresis separation or heterogeneous analysis. In this paper, we report a novel homogeneous LCR assay by using cationic conjugated polymers (CCPs) as an indicator for detection of single-nucleotide polymorphism (SNP). For LCR, we design two pairs of unique target-complement probes. Each pair of probes contains two adjacent probes, in which one probe is designed with phosphorothioate modification at its 3'-end, and the other probe is labeled with fluorescein at its 5'-end. After the LCR, the two adjacent probes are ligated to form one DNA strand with a fluorescein label at its 5'-end and phosphorothioate modification at its 3'-end, which is resistant to the exonuclease I and exonuclease III degradation. When the CCP is added, because of the strong electrostatic interactions between CCP and DNA, effective fluorescence resonance energy transfer (FRET) from the CCP to the fluorescein-labeled DNA can be observed. In contrast, the unligated fluorescein-labeled probes are degraded to the mononucleotides by exonuclease I and exonuclease III. Introduction of CCP leads to inefficient FRET results because much weaker electrostatic interactions between the fluorescein-labeled mononucleotides and CCP keep the fluorescein far away from CCP. Accordingly, homogeneous LCR for SNP detection is performed successfully. The method is sensitive and specific enough to detect 1 fM (600 zmol) DNA molecules. It is possible to quantify SNP and accurately determine the allele frequency as low as 1.0%. This proposed assay strategy extends the application of LCR and provides a new platform for homogeneous detection of SNP.
    Analytical Chemistry 03/2012; 84(8):3739-44. · 5.70 Impact Factor