False-negative Results In Detection Research Articles

A novel split PEC sensor based on magneto–optic nanostructure and photocurrent polarity switching strategy

BackgroundPhotoelectrochemical (PEC) sensors have attracted much attention due to their low cost, simple instrumentation and high sensitivity. However, conventional PEC sensors require layer–by–layer modification of the photoelectrode surface, which has the disadvantages of being time–consuming and unstable. In addition, complex interfering substances in real samples may lead to false–positive or false–negative detection results. It was thought that the above drawbacks could be eliminated by the construction of a polarity inversion PEC sensor. In this work, a magnetically separated PEC sensor was constructed for the detection of Carcinoembryonic antigen (CEA). ResultsDuring the experiment, the construction of the sensor was used for sensitive detection of CEA. In the experimental process, Fe3O4@SiO2@CdS, a semiconductor material with magnetic properties, was chosen as the substrate material, and ZnO/CuO was used as the marker on the DNA2 molecule, and a split magnetic separation PEC sensor was constructed, which was used to realize the sensitive detection of CEA. Eventually, the detection range of the sensor for CEA detection is 1–10000 pg/mL, with the detection limit of 0.34 pg/mL. Additionally, the PEC sensor has the advantages of high speed, high efficiency, high sensitivity, good specificity, and high stability. The sensing platform constructed in this work can also be extended to detect other targets, which provides a new idea for PEC sensing platforms. SignificanceIn this experiment, we developed a split PEC immunosensor based on magneto–optic nanostructure and photocurrent polarity switching strategy. Specifically, the proposed magnetic nanostructure Fe3O4@SiO2@CdS–DNA1 exhibits good paramagnetism and dispersion ability. By magnetic separation process, the PEC signals of opposite polarity can be obtained.

Construction of an aptamer sensor for sensitive detection of AOH based on the enhancement of light/electric dual signaling response of Ru/Cu-THQ by Ag NCs

Precise detection of food safety is a hotspot and challenging aspect in contemporary scientific research. This study utilized Ag nanocubes (Ag NCs) to augment the electrogenerated chemiluminescence (ECL) and electrochemical (EC) dual-response signals of Ru/Cu-tetrahydroxybenzoquinone (Ru/Cu-THQ). Consequently, a novel aptamer sensor was developed for the trace detection of Alternariol (AOH). This dual-mode sensor offers several advantages: (1) The output of dual-channel signals significantly reduces the likelihood of false-positive and false-negative detection results, which are common in traditional single-mode sensing. (2) Ru/Cu-THQ effectively coordinates dual-channel outputs and exhibits excellent ECL and EC behavior. (3) Ag NCs, due to their strong K2S2O8 activation ability and excellent conductivity, further amplify the sensor's response signal. This sensor demonstrates effective detection performance for AOH in the concentration range of 0.01–100 ng/mL, offering a novel approach for accurate food safety detection and potential application in real sample analysis.

A Ratiometric Fluorescent Biosensor Based on Exonuclease III Amplification Strategy for Pathogenic Bacterial Gene Detection

Food-borne pathogenic bacteria seriously threaten public health.Based on the mechanism of fluorescence resonance energy transfer (FRET), a ratiometric fluorescence biosensor was constructed by integration of Exo Ⅲ-based signal amplification strategy.The Cy3 labeled R1-DNA firstly hybridized with Cy5 labeled R2-DNA to form duplex of R1/R2.Cy3 showed a low fluorescence response while Cy5 showed a high fluorescence response.The addition of target pathogenic bacterial gene (Lac Z gene) could de-hybridize the R1/R2, resulting in the fluorescence decreasing of Cy5 and the fluorescence recovering of Cy3.Under the assistance of Exo Ⅲ, the signal change was further amplified.The detection of limit reached as low as 5.29 pmol/L.The linear detection range was from 10 pmol/L to 2000 pmol/L.The developed ratiomtric detection strategy significantly reduced the possibility of false-positive and false-negative detection results.

Randomly primed, strand-switching, MinION-based sequencing for the detection and characterization of cultured RNA viruses.

RNA viruses rapidly mutate, which can result in increased virulence, increased escape from vaccine protection, and false-negative detection results. Targeted detection methods have a limited ability to detect unknown viruses and often provide insufficient data to detect coinfections or identify antigenic variants. Random, deep sequencing is a method that can more fully detect and characterize RNA viruses and is often coupled with molecular techniques or culture methods for viral enrichment. We tested viral culture coupled with third-generation sequencing for the ability to detect and characterize RNA viruses. Cultures of bovine viral diarrhea virus, canine distemper virus (CDV), epizootic hemorrhagic disease virus, infectious bronchitis virus, 2 influenza A viruses, and porcine respiratory and reproductive syndrome virus were sequenced on the MinION platform using a random, reverse primer in a strand-switching reaction, coupled with PCR-based barcoding. Reads were taxonomically classified and used for reference-based sequence building using a stock personal computer. This method accurately detected and identified complete coding sequence genomes with a minimum of 20× coverage depth for all 7 viruses, including a sample containing 2 viruses. Each lineage-typing region had at least 26× coverage depth for all viruses. Furthermore, analyzing the CDV sample through a pipeline devoid of CDV reference sequences modeled the ability of this protocol to detect unknown viruses. Our results show the ability of this technique to detect and characterize dsRNA, negative- and positive-sense ssRNA, and nonsegmented and segmented RNA viruses.

Association Between Early Stage Colon Neoplasms and False-negative Results From the Fecal Immunochemical Test

The fecal immunochemical test (FIT) can identify patients with advanced colorectal neoplasms, but it also has a high rate of false-negative results. It would be helpful to characterize colorectal neoplasms that are not detected by FIT to aid in development of new tests. We characterized colorectal neoplasms from patients who had negative results from the FIT. We analyzed data from 18,296 subjects who were screened for colorectal cancer by colonoscopy and the FIT at the Health Management Center of National Taiwan University Hospital from September 2005 through September 2010. We identified 4045 subjects with colorectal neoplasms (3385 with nonadvanced adenomas, 632 with advanced adenomas, and 28 with cancer). We analyzed the sensitivity of the FIT in identifying these patients, along with information on lesion size, location, and morphology. The FIT identified patients with nonadvanced adenomas, advanced adenomas, and cancer with sensitivity values of 10.6% (95% confidence interval [CI], 10.2%-12.3%), 28.0% (95% CI, 24.6%-31.7%), and 78.6% (95% CI, 58.5%-91.0%), respectively. The FIT detected proximal advanced adenomas and nonpolypoid lesions with lower levels of sensitivity than distal advanced adenomas; it had a high false-negative rate in detection of adenomas <15 mm (adjusted odds ratio, 2.85; 95% CI, 1.79-4.54) and nonpolypoid adenomas (adjusted odds ratio, 2.15; 95% CI, 1.22-3.80), after adjusting for demographic characteristics, colonoscopy findings, and potential confounders. The FIT produced a higher percentage of false-negative results in detection of carcinoma in situ and T1 cancer than in T2-T4 cancers (66.7% sensitivity vs 100%; P = .049). The FIT produces a high rate of false-negative results for patients with small or nonpolypoid adenomas. Early-stage cancers are associated with a high rate of false-negative results from the FIT.

False-Negative Results in Detection of Monoclonal Proteins by Capillary Zone Electrophoresis: A Prospective Study

Over the last 5 years, capillary zone electrophoresis (CZE) with the use of fused-silica capillaries has been increasingly introduced in clinical laboratories for routine serum-protein electrophoresis (1). The multichannel, automated Paragon CZE 2000 instrument (seven capillaries in parallel; Beckman Coulter) represented an especially attractive alternative to time-consuming manual techniques. CZE has been documented to perform reliably for the analysis of serum proteins and for the detection of monoclonal components (2)(3). We reported (4) that the sensitivity of the Paragon CZE 2000 system for the detection of monoclonal components (93%) was superior to the sensitivity of cellulose acetate gel electrophoresis (74%) and agarose gel electrophoresis (86%). In a prospective study, Katzman et al. (5) reported sensitivities of 95% and 91% for seven-capillary electrophoresis and agarose gel electrophoresis, respectively. When compared with agarose gel electrophoresis, CZE was able to detect more low-concentration IgA monoclonal components or light chains that were hidden in agarose gel electrophoresis because of comigration with transferrin or C3 (6). Paraproteins that are missed by CZE are typically very low-concentration monoclonal components that are also missed by agarose gel electrophoresis, but not by immunofixation. Problems with the detection of monoclonal components by CZE have been described (7)(8). Using a single-capillary Beckman P/ACE instrument with a capillary and buffer different from the Paragon CZE 2000 system, Jenkins and Guerin (7) performed a prospective study on 5500 specimens in which they compared CZE with agarose gel electrophoresis for the detection of monoclonal components. The authors identified six paraproteins that did not separate correctly on CZE. On agarose gel electrophoresis, all of these proteins migrated in the very slow γ region. The pI …

Accuracy of prospective two-dimensional echocardiographic evaluation of left ventricular outflow tract in complete transposition of the great arteries

Thirty-two consecutive infants with transposition of the great arteries (TGA) and ventricular septal defect underwent subxiphoid 2-dimensional echocardiography (2-D echo). Two independent observers prospectively evaluated each echocardiogram for the presence or absence of left ventricular (LV) outflow tract obstruction, whether outflow obstruction was dynamic or fixed, or both, and the precise anatomic type of fixed obstruction. Compared with the LV-to-pulmonary artery gradient determined at cardiac catheterization, 2-D echo yielded low false-negative (7 to 13%) and false-positive (0 to 6%) rates for diagnosing the presence or absence of LV outflow tract obstruction. Moreover, the false-negative cases were only minor errors, because the measured LV-pulmonary artery gradients proved to be less than 25 mm Hg. Compared with the long-axial oblique LV angiogram, 2-D echo yielded no false-negative results in detection of outflow tract obstruction, which was at least partly fixed. Compared with autopsy/surgical observation, 2-D echo made no significant errors in delineating the exact anatomic type of fixed obstruction. The diagnostic accuracy of 2-D echo in detecting and characterizing LV outflow tract obstruction limits the need for “routine” cardiac catheterization before repair in infants with TGA and intact ventricular septum. Furthermore, because certain types of fixed LV outflow tract obstruction are difficult for the surgeon to visualize and alleviate, precise knowledge of the anatomic type of fixed obstruction influences the choice among Rastelli, intraatrial baffle and arterial switch procedures in patients with TGA and ventricular septal defect.