title: Direct fluorescence in situ hybridization (FISH) in Escherichia coli with a target-specific quantum dot-based molecular beacon.
abstract: Quantum dots (QDs) are inorganic fluorescent nanocrystals with excellent properties such as tunable emission spectra and photo-bleaching resistance compared with organic dyes, which make them appropriate for applications in molecular beacons. In this work, quantum dot-based molecular beacons (QD-based MBs) were fabricated to specifically detect β-lactamase genes located in pUC18 which were responsible for antibiotic resistance in bacteria Escherichia coli (E. coli) DH5α. QD-based MBs were constructed by conjugating mercaptoacetic acid-quantum dots (MAA-QDs) with black hole quencher 2 (BHQ2) labeled thiol DNA vial metal-thiol bonds. Two types of molecular beacons, double-strands beacons and hairpin beacons, were observed in product characterization by gel electrophoresis. Using QD-based MBs, one-step FISH in tiny bacteria DH5α was realized for the first time. QD-based MBs retained their bioactivity when hybridizing with complementary target DNA, which showed excellent advantages of eliminating background noise caused by adsorption of non-specific bioprobes and achieving clearer focus of genes in plasmids pUC18, and capability of bacterial cell penetration and signal specificity in one-step in situ hybridization.
authors: Key Laboratory of Analytical Chemistry for Biology and Medicine (Ministry of Education), College of Chemistry and Molecular Sciences, State Key Laboratory of Virology, Wuhan University, Wuhan 430072, PR China.
authors: Sheng-Mei
authors: SM
authors: Wu
authors: Zhi-Quan
authors: ZQ
authors: Tian
authors: Zhi-Ling
authors: ZL
authors: Zhang
authors: Bi-Hai
authors: BH
authors: Huang
authors: Peng
authors: P
authors: Jiang
authors: Zhi-Xiong
authors: ZX
authors: Xie
authors: Dai-Wen
authors: DW
authors: Pang
mesh_terms: D015342:DNA Probes / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics*; D018390:Gene Targeting / Q000379:methods*; D017404:In Situ Hybridization, Fluorescence / Q000379:methods*; D015336:Molecular Probe Techniques; D045663:Quantum Dots; D001618:beta-Lactamases / Q000235:genetics*
chemical_list: D015342:DNA Probes; D001618:beta-Lactamases