Electrocatalytic Mechanism for Improving Sensitivity and Specificity of Electrochemical Nucleic Acid-Based Sensors with Covalent Redox Tags—Part I

ACS Sensors ◽  
2020 ◽  
Vol 5 (12) ◽  
pp. 3833-3841
Author(s):  
Yao Wu ◽  
Sufyaan Ali ◽  
Ryan J. White
2020 ◽  
Vol 117 (41) ◽  
pp. 25722-25731 ◽  
Author(s):  
Rose A. Lee ◽  
Helena De Puig ◽  
Peter Q. Nguyen ◽  
Nicolaas M. Angenent-Mari ◽  
Nina M. Donghia ◽  
...  

Asymptomatic carriers ofPlasmodiumparasites hamper malaria control and eradication. Achieving malaria eradication requires ultrasensitive diagnostics for low parasite density infections (<100 parasites per microliter blood) that work in resource-limited settings (RLS). Sensitive point-of-care diagnostics are also lacking for nonfalciparum malaria, which is characterized by lower density infections and may require additional therapy for radical cure. Molecular methods, such as PCR, have high sensitivity and specificity, but remain high-complexity technologies impractical for RLS. Here we describe a CRISPR-based diagnostic for ultrasensitive detection and differentiation ofPlasmodium falciparum,Plasmodium vivax,Plasmodium ovale, andPlasmodium malariae, using the nucleic acid detection platform SHERLOCK (specific high-sensitivity enzymatic reporter unlocking). We present a streamlined, field-applicable, diagnostic comprised of a 10-min SHERLOCK parasite rapid extraction protocol, followed by SHERLOCK for 60 min forPlasmodiumspecies-specific detection via fluorescent or lateral flow strip readout. We optimized one-pot, lyophilized, isothermal assays with a simplified sample preparation method independent of nucleic acid extraction, and showed that these assays are capable of detection below two parasites per microliter blood, a limit of detection suggested by the World Health Organization. OurP. falciparumandP. vivaxassays exhibited 100% sensitivity and specificity on clinical samples (5P. falciparumand 10P. vivaxsamples). This work establishes a field-applicable diagnostic for ultrasensitive detection of asymptomatic carriers as well as a rapid point-of-care clinical diagnostic for nonfalciparum malaria species and low parasite densityP. falciparuminfections.


2020 ◽  
Vol 5 (4) ◽  
pp. 1-29
Author(s):  
Farid E. Ahmed ◽  
Mostafa M. Gouda ◽  
Nancy C. Ahmed

Isolation methods that employ readily-available inexpensive supplies on the open market, which are reliable, as well as economical, such as nucleic acid amplification techniques (NAAT) based on microfluidic technology in low-resource research settings (LRRS) that meets the ASSURED guidelines are essential to develop a noninvasive diagnostic colon cancer screen in stool using micro(mi)RNA molecules. A combination of a microfluidic-based MiRNA stool test with a reliable rolling circle amplification/detection method applied to the quantification of miRNA molecules, result in an affordable sensitive and specific isothermal method for the noninvasive quantitative detection of miRNAs in LRRS. Scientists and engineers have become interested in miRNAs, and they have intensified their efforts to apply emerging simple detection tools to the important bioanalytical challenge of quantifying these small 18-26 nt long molecules. Some of the proposed approaches incorporate novel material, such as simple centrifuges and methods based on microfluidic technology, while others utilize the interesting biological properties of these molecules, such as forming branched RCA structures, allowing for the detection of these biomarker molecules at an attomolar "aM" concentration level, using low cost extraction and isothermal amplification methods in LRRS. We have been interested in studying colorectal cancer (CRC) because it is the 3rd most common malignancy worldwide, and stool can be obtained noninvasively from the patients. We have focused in this research on colon cancer (CC) because it is more common in the USA than rectal cancer (RC). The innovation of our approach lies in the exploratory use of an affordable, quantitative miRNA profiling in noninvasive stool samples in LRRS, whose extracted fragile total RNA is stabilized shortly after excretion from stool by commercially available kits, so it does not ever fragment, followed by quantitative standardized analytical tests that are neither labor intensive, nor require expensive instrumentation, in order to develop apanel of novel miRNA genes for the noninvasive diagnostic screening of early left and right sporadic colon cancers, more economically, and with higher sensitivity and specificity than any other colon cancer screening test currently available on the market. To show the clinical sensitivity and specificity of the proposed quantitative miRNA test using simple methodologies in LRRS,the miRNA results are to be correlated with FOBT, colonoscopy, and pathology data. Standardization establishes test’s performance criteria (sample selection, optimal sample running conditions, preservation and storage), in order to ensure that the assay will perform the same way in any laboratory, by any trained personnel, anywhere in low-resource laboratory settings worldwide.


Author(s):  
RASHMI M. KARIGOUDAR ◽  
MAHESH H. KARIGOUDAR ◽  
SANJAY M. WAVARE ◽  
LAKSHMI KAKHANDKI ◽  
SMITHA BAGALI

Objective: Tuberculosis is an airborne infection caused by Mycobacterium tuberculosis. Timely diagnosis and treatment are important to prevent the spread of infection. Cartridge-based nucleic acid amplification test (CBNAAT) provides a valuable tool in the early detection of TB. This study is undertaken to evaluate the utility of CBNAAT for the detection of MTB. Comparison of cartridge-based nucleic acid amplification testing with ZN staining. Methods: This prospective observational study was carried out in the Department of Microbiology, BLDEDU’s Shri B. M. Patil Medical College, Hospital and RC and Dr. Karigoudar Diagnostic Laboratory, Vijayapur. A total of 129 samples from patients with the presumptive diagnosis of TB based on history, clinical presentation, and radiological findings were included in the study. All samples were subjected to ZN staining, and Cartridge-based nucleic acid amplification test and data were analyzed. Results: The present study showed ZN smear positivity of 7.75% and CBNAAT positivity of 19.38%. CBNAAT sensitivity and specificity were 90% and 86.55, respectively, compared with ZN staining with a significant P value of <0.001. Conclusion: CBNAAT helps diagnose TB and detect rifampicin resistance within 2-3 h with high sensitivity and specificity. Rifampicin resistance detection is of great concern, which otherwise leads to treatment failure and on time spread of multidrug resistance TB, leading to increased morbidity and mortality.


1998 ◽  
Vol 36 (2) ◽  
pp. 375-381 ◽  
Author(s):  
Timothy A. Green ◽  
Carolyn M. Black ◽  
Robert E. Johnson

When a new diagnostic test is potentially more sensitive than the reference test used to classify persons as infected or uninfected, a substantial number of specimens from infected persons may be reference-test negative but new-test positive. Discrepant analysis involves the performance of one or more additional tests with these specimens, reclassification as infected those persons for whom the new-test-positive results are confirmed, and recalculation of the estimates of new-test sensitivity and specificity by using the revised classification. This approach has been criticized because of the bias introduced by the selective use of confirmation testing. Under conditions appropriate for evaluating a nucleic acid amplification (NAA) test for Chlamydia trachomatis infection with cell culture as the reference test, we compared the bias in estimates based on the discrepant-analysis classification of persons as infected or uninfected with that in estimates based on the culture classification. We concluded that the bias in estimates of NAA-test specificity based on discrepant analysis is small and generally less than that in estimates based on culture. However, the accuracy of discrepant-analysis-based estimates of NAA-test sensitivity depends critically on whether culture specificity is equal to or is slightly less than 100%, and it is affected by competing biases that are not fully taken into account by discrepant analysis.


Author(s):  
Roberto W. Dal Negro ◽  
Maria Visconti ◽  
Claudio Micheletto ◽  
Fiorenza Trevisan ◽  
Stefano Bertacco ◽  
...  

Cancers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 1117
Author(s):  
Svenja Engels ◽  
Lutz Brautmeier ◽  
Lena Reinhardt ◽  
Clara Wasylow ◽  
Friederike Hasselmann ◽  
...  

Background: In clinical routine, only fractions of lymph nodes (LNs) are examined histopathologically, often resulting in missed (micro-)metastases and incorrect staging of prostate cancer (PCa). One-step nucleic acid amplification (OSNA) analyzes the entire LN by detecting cytokeratin 19 (CK19) mRNA as a surrogate for LN metastases requiring less effort than conventional biomolecular techniques. We aimed to evaluate performance of OSNA in detecting sentinel LN (SLN) metastases in PCa. Methods: SLNs (n = 534) of 64 intermediate- or high-risk PCa patients undergoing radical prostatectomy with extended and sentinel-guided lymphadenectomy were cut into slices and alternatingly assigned to OSNA and histopathology (hematoxylin-eosin staining, CK19, and CK AE1/AE3 immunohistochemistry). Sensitivity and specificity of OSNA and concordance and measure of agreement (Cohen’s kappa (κ)) between OSNA and histopathology were assessed. Results: Histopathology revealed metastases in 76 SLNs. Sensitivity and specificity of OSNA were 84.2% and 96.1%, respectively. Discordant results were recorded for 30 of 534 SLNs, revealing high concordance (94.4%). Twenty-four discordant cases were classified as micrometastases, indicating a possible allocation bias. In 18 cases, positive results were conferred only by OSNA resulting in seven LN-positive patients who were missed by histopathology. Overall, the level of agreement was high (κ = 0.78). Conclusions: OSNA provided a diagnosis that was as least as accurate as detailed histological examination and might improve LN staging in PCa.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Chien-Ru Lin ◽  
Hsin-Yao Wang ◽  
Ting-Wei Lin ◽  
Jang-Jih Lu ◽  
Jason Chia-Hsun Hsieh ◽  
...  

AbstractThe Mycobacterium tuberculosis complex (MTBC) remains one of the top 10 leading causes of death globally. The early diagnosis of MTBC can reduce mortality and mitigate disease transmission. However, current nucleic acid amplification diagnostic test methods are generally time-consuming and show suboptimal diagnostic performance, especially in extrapulmonary MTBC samples or acid-fast stain (AFS)-negative cases. Thus, development of an accurate assay for the diagnosis of MTBC is necessary, particularly under the above mentioned conditions. In this study, a single-tube nested real-time PCR assay (N-RTP) was developed and compared with a newly in-house-developed high-sensitivity real-time PCR assay (HS-RTP) using 134 clinical specimens (including 73 pulmonary and 61 extrapulmonary specimens). The amplification efficiency of HS-RTP and N-RTP was 99.8% and 100.7%, respectively. The sensitivity and specificity of HS-RTP and N-RTP for the diagnosis of MTBC in these specimens were 97.5% (77/79) versus 94.9% (75/79) and 80.0% (44/55) versus 89.1% (49/55), respectively. The sensitivity and specificity of HS-RTP and N-RTP for the diagnosis of MTBC in pulmonary specimens were 96.3% (52/54) versus 96.3% (52/54) and 73.7.0% (14/19) versus 89.5% (17/19), respectively; in extrapulmonary specimens, the sensitivity and specificity of HS-RTP and N-RTP were 100% (25/25) versus 92% (23/25) and 83.3% (30/36) versus 88.9% (32/36), respectively. Among the AFS-negative cases, the sensitivity and specificity of HS-RTP and N-RTP were 97.0% (32/33) versus 90.9% (30/33) and 88.0% (44/50) versus 92.0% (46/50), respectively. Overall, the sensitivity of HS-RTP was higher than that of N-RTP, and the performance was not compromised in extrapulmonary specimens and under AFS-negative conditions. In contrast, the specificity of the N-RTP assay was higher than that of the HS-RTP assay in all types of specimens. In conclusion, the HS-RTP assay would be useful for screening patients suspected of exhibiting an MTBC infection due to its higher sensitivity, while the N-RTP assay could be used for confirmation because of its higher specificity. Our results provide a two-step method (screen to confirm) that simultaneously achieves high sensitivity and specificity in the diagnosis of MTBC.


2020 ◽  
Author(s):  
Hong Yue ◽  
Radosław P Nowak ◽  
Daan Overwijn ◽  
N Connor Payne ◽  
Stephanie Fischinger ◽  
...  

The human beta coronavirus SARS-CoV-2, causative virus of COVID-19, has infected more than 15 million people globally and continues to spread. Widespread, population level testing to detect active and past infections is critical to curb the COVID-19 pandemic. Antibody (serological) testing is the only option for detecting past infections outside the narrow window accessible to nucleic acid-based tests. However, currently available serological assays commonly lack scalability. Here, we describe the development of a rapid homogenous serological assay for the detection of antibodies to SARS-CoV-2 in patient plasma. We show that the fluorescence-based assay accurately detects seroconversion in COVID-19 patients from less than 1 microliter of plasma. Using a cohort of samples from COVID-19 infected or healthy individuals, we demonstrate detection with 100% sensitivity and specificity. This assay addresses an important need for a robust, low barrier to implementation, and scalable serological assay with complementary strengths to currently available serological platforms.


2021 ◽  
Author(s):  
Sri Gowtham Thakku ◽  
Cheri M Ackerman ◽  
Cameron Myhrvold ◽  
Roby P Bhattacharyya ◽  
Jonathan Livny ◽  
...  

Rapid and accurate diagnosis of infections is fundamental to individual patient care and public health management. Nucleic acid detection methods are critical to this effort, but are limited either in the breadth of pathogens targeted or by the expertise and infrastructure required. We present here a high-throughput system that enables rapid identification of bacterial pathogens, bCARMEN, which utilizes: (1) modular CRISPR-Cas13-based nucleic acid detection with enhanced sensitivity and specificity; and (2) a droplet microfluidic system that enables thousands of simultaneous, spatially multiplexed detection reactions at nanoliter volumes; and (3) a novel pre-amplification strategy that further enhances sensitivity and specificity. We demonstrate bCARMEN is capable of detecting and discriminating 52 clinically relevant bacterial species and several key antibiotic resistance genes. We further develop a proof of principle system for use with stabilized reagents and a simple workflow with optical readout using a cell phone camera, opening up the possibility of a rapid point-of-care multiplexed bacterial pathogen identification and antibiotic susceptibility testing.


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