Caihui Luo

Chongqing Medical University, Ch’ung-ch’ing-shih, Chongqing Shi, China

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Publications (6)20.7 Total impact

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    ABSTRACT: We have developed a sensitive assay for enteropathogenic E. coli (EPEC) by integrating DNA extraction, specific polymerase chain reaction (PCR) and DNA detection using an electrode modified with the bundle-forming pilus (bfpA) structural gene. The PCR amplified products are captured on the electrode and hybridized with biotinylated detection probes to form a sandwich hybrid containing two biotinylated detection probes. The sandwich hybridization structure significantly combined the numerous streptavidin alkaline phosphatase on the electrode by biotin-streptavidin connectors. Electrochemical readout is based on dual signal amplification by both the sandwich hybridization structure and the enzyme. The electrode can satisfactorily discriminate complementary and mismatched oligonucleotides. Under optimal conditions, synthetic target DNA can be detected in the 1 pM to 10 nM concentration range, with a detection limit of 0.3 pM. EPEC can be quantified in the 10 to 107 CFU mL−1 levels within 3.5 h. The method also is believed to present a powerful platform for the screening of pathogenic microorganisms in clinical diagnostics, food safety and environmental monitoring. An electrochemical DNA sensor was first designed to detect a bfpA gene specifically related to the EPEC.
    No preview · Article · Oct 2013 · Microchimica Acta
  • Hu Fu · Chuang Ge · Wei Cheng · Caihui Luo · Decai Zhang · Li Yan · Yun He · Gang Yi
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    ABSTRACT: An electrochemical aptasensor was developed for sensitive and specific detection of thrombin by combining homogenous recognition strategy and gold nanoparticles (AuNPs) amplification. Streptavidin-alkaline phosphatase was used as reporter molecule. Compared with the traditional hairpin aptasensor monitoring the distance of the redox molecule from the electrode surface, the proposed aptasensor successfully overcome the limitations of distance and improved the stability and high affinity of the aptamer hairpin through homogenous recognition, which enhanced the sensitivity and selectivity of the sensors effectively. Additionally, AuNPs were employed to increase the active area and conductivity of the electrode, thus, improving the sensitivity of the aptasensor. As a result, the designed thrombin detection sensor obtained a lower detection limit of 0.52 pM in buffer and 6.9 pM in blood serum.
    No preview · Article · May 2013 · Electroanalysis
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    ABSTRACT: A specific and sensitive methodology was developed successfully for quantitative detection of Enterobacteriaceae bacteria by integrating Exonuclease III-assisted target recycling amplification with a simple electrochemical DNA biosensor. After target DNA hybridizes with capture DNA, Exonuclease III can selectively digest the capture DNA, which releases the target to undergo a new hybridization and cleavage cycle on sensor surface, leading to a successful target recycling. Finally, the left capture DNA is recognized by detection probe to produce the detectable signal, which decreases with the increasing target DNA concentration. Under the optimal conditions, the proposed strategy could detect target DNA down to 8.7fM with a linear range from 0.01pM to 1nM, showing high sensitivity. Meanwhile, the sensing strategy was successfully used for detection of Enterobacteriaceae bacteria down to 40CFUmL(-1) in milk samples. This strategy presented a simple, rapid and sensitive platform for Enterobacteriaceae bacteria detection and would become a versatile and powerful tool for food safety, biothreat detection and environmental monitoring.
    No preview · Article · Apr 2013 · Biosensors & Bioelectronics
  • Li Yan · Caihui Luo · Wei Cheng · Wei Mao · Decai Zhang · Shijia Ding
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    ABSTRACT: A novel electrochemical aptasensor for highly sensitive detection of Chloramphenicol (CAP) in honey was successfully developed based on target-induced strand release (TISR). CAP aptamer was immobilized on electrode and then hybridized with the complementary biotinylated detection probe to form aptamer/DNA duplex. In the presence of CAP, the TISR resulted in the dissociation of biotinylated detection probe from the electrode. Then the binding of streptavidin–alkaline phosphatase (ST–AP) to the remaining biotinylated detection probe led to enzyme-amplified electrochemical signal, which decreased with the increase of CAP concentration. Under optimal conditions, the electrochemical signal was linear with the logarithm of CAP concentrations in the range from 1 nM to 1000 nM with the detection limit of 0.29 nM of CAP. In addition, the designed strategy allowed the direct analysis of real honey samples and the results showed a good agreement with conventional LC–MS/MS method.
    No preview · Article · Nov 2012 · Journal of electroanalytical chemistry
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    ABSTRACT: An electrochemical immunosensor for detection of neuron specific enolase (NSE) was designed by immobilizing NSE covalently functionalized single-walled carbon nanotubes (NSE-SWNTs) on a glassy carbon electrode. The NSE-SWNTs not only enhanced electrochemical signal but also presented abundant antigen domains for competitive immunological recognition to anti-NSE primary antibody and then gold nanoprobes labeled with alkaline phosphatase conjugated secondary antibody (AP-anti-IgG/AuNPs). The AP-anti-IgG/AuNPs exhibited highly catalytic activity toward enzyme substrate and significantly amplified the amperometric signal for target molecule detection. Based on the dual signal amplification of SWNTs and gold nanoprobe, the immunosensor could response down to 0.033 ng mL(-1) NSE with a linear range from 0.1 ng mL(-1) to 2 μg mL(-1), and showed acceptable precision and reproducibility. The designed immunosensor was amenable to direct quantification of target protein with a wide range of concentration in complex clinical serum specimens. The assay results were in a good agreement with the reference values. The proposed electrochemical immunosensor provided a pragmatic platform for convenient detection of tumor markers in clinical diagnosis.
    No preview · Article · May 2012 · Talanta
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    ABSTRACT: AbstractA sensitive and specific electrochemical biosensor based on target‐induced aptamer displacement was developed for direct detection of Escherichia coli O111. The aptamer for Escherichia coli O111 was immobilized on a gold electrode by hybridization with the capture probe anchored on the electrode surface through Au‐thiol binding. In the presence of Escherichia coli O111, the aptamer was dissociated from the capture probe‐aptamer duplex due to the stronger interaction between the aptamer and the Escherichia coli O111. The consequent single‐strand capture probe could be hybridized with biotinylated detection probe and tagged with streptavidin‐alkaline phosphatase, producing sensitive enzyme‐catalyzed electrochemical response to Escherichia coli O111. The designed biosensor showed weak electrochemical signal to Salmonella typhimurium, Staphylococcus aureus and common non‐pathogenic Escherichia coli, indicating high specificity for Escherichia coli O111. Under the optimal conditions, the proposed strategy could directly detect Escherichia coli O111 with the detection limit of 112 CFU mL−1 in phosphate buffer saline and 305 CFU mL−1 in milk within 3.5 h, demonstrated the sensitive and accurate quantification of target pathogenic bacteria. The designed biosensor could become a powerful tool for pathogenic microorganisms screening in clinical diagnostics, food safety, biothreat detection and environmental monitoring.
    Preview · Article · May 2012 · Electroanalysis