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Lim J, Zhou S, Baek J, Kim AY, Valera E, Sweedler J, Bashir R. A Blood Drying Process for DNA Amplification. Small 2024; 20:e2307959. [PMID: 37888793 DOI: 10.1002/smll.202307959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Indexed: 10/28/2023]
Abstract
The presence of numerous inhibitors in blood makes their use in nucleic acid amplification techniques difficult. Current methods for extracting and purifying pathogenic DNA from blood involve removal of inhibitors, resulting in low and inconsistent DNA recovery rates. To address this issue, a biphasic method is developed that simultaneously achieves inhibitor inactivation and DNA amplification without the need for a purification step. Inhibitors are physically trapped in the solid-phase dried blood matrix by blood drying, while amplification reagents can move into the solid nano-porous dried blood and initiate the amplification. It is demonstrated that the biphasic method has significant improvement in detection limits for bacteria such as Escherichia coli, Methicillin-resistant Staphylococcus aureus, Methicillin-Sensitive Staphylococcus aureus using loop-mediated isothermal amplification (LAMP) and recombinase polymerase amplification (RPA). Several factors, such as drying time, sample volume, and material properties are characterized to increase sensitivity and expand the application of the biphasic assay to blood diagnostics. With further automation, this biphasic technique has the potential to be used as a diagnostic platform for the detection of pathogens eliminating lengthy culture steps.
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Affiliation(s)
- Jongwon Lim
- Nick Holonyak Jr. Micro and Nanotechnology Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Shuaizhen Zhou
- Department of Energy Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Janice Baek
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Alicia Yeaeun Kim
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Enrique Valera
- Nick Holonyak Jr. Micro and Nanotechnology Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Jonathan Sweedler
- Department of Energy Center for Advanced Bioenergy and Bioproducts Innovation, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Carl R. Woese Institute for Genomic Biology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Rashid Bashir
- Nick Holonyak Jr. Micro and Nanotechnology Laboratory, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Department of Biomedical and Translational Science, Carle Illinois College of Medicine, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
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Kim U, Lee SY, Oh SW. Thermophilic helicase-dependent amplification-based CRISPR/Cas12a system: Detection of stx2 in Escherichia coli O157:H7 by controlling primer dimers. Anal Chim Acta 2023; 1239:340679. [PMID: 36628706 DOI: 10.1016/j.aca.2022.340679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 11/25/2022] [Accepted: 11/26/2022] [Indexed: 12/04/2022]
Abstract
BACKGROUND s: To overcome the limitation of polymerase chain reaction (PCR), isothermal amplification methods such as thermophilic helicase-dependent amplification (tHDA) have been developed. However, formation of primer dimer due to the single amplification temperature are major problems of tHDA. When cross-dimerization of forward and reverse primer occurred, false-positive results can be found on the lateral flow assay (LFA) which is one of the major detection methods widely used as a point of care diagnosis. Therefore, specific method of detecting only the target amplicon is required. RESULTS In this study, a tHDA-based CRISPR/Cas12a system was developed to detect low levels of Escherichia coli O157:H7 in fresh salad mix without the false-positive results produced by primer dimers. For the comparison of the effect in eliminating false-positive results by CRISPR/Cas12a system, LFA was also evaluated. The tHDA-based CRISPR/Cas12a system detected as low as 101 CFU/mL E. coli O157:H7 in bacterial pure culture. In LFA false-positive results were produced due to the primer dimer, whereas the primer dimer produced by tHDA was not detected in the CRISPR/Cas12a system. These results indicated that the CRISPR/Cas12a system eliminated the formation of primer dimer. In fresh salad mix, the tHDA-based CRISPR/Cas12a system combined with the filter concentration method detected 103 CFU/g E. coli O157:H7. CONCLUSION This study was the first to amplify stx2 of E. coli O157:H7 with tHDA as an isothermal amplification method and detected the amplicon without false-positive results by combining tHDA with CRISPR/Cas12a. Therefore, this study showed great potential for detecting low levels of E. coli O157:H7 present in fresh salad mix.
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Affiliation(s)
- Unji Kim
- Department of Food and Nutrition, Kookmin University, Seoul, Republic of Korea
| | - So-Young Lee
- Department of Food and Nutrition, Kookmin University, Seoul, Republic of Korea
| | - Se-Wook Oh
- Department of Food and Nutrition, Kookmin University, Seoul, Republic of Korea.
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Ganguli A, Lim J, Mostafa A, Saavedra C, Rayabharam A, Aluru NR, Wester M, White KC, Kumar J, McGuffin R, Frederick A, Valera E, Bashir R. A culture-free biphasic approach for sensitive and rapid detection of pathogens in dried whole-blood matrix. Proc Natl Acad Sci U S A 2022; 119:e2209607119. [PMID: 36161889 DOI: 10.1073/pnas.2209607119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Blood stream infections (BSIs) cause high mortality, and their rapid detection remains a significant diagnostic challenge. Timely and informed administration of antibiotics can significantly improve patient outcomes. However, blood culture, which takes up to 5 d for a negative result, followed by PCR remains the gold standard in diagnosing BSI. Here, we introduce a new approach to blood-based diagnostics where large blood volumes can be rapidly dried, resulting in inactivation of the inhibitory components in blood. Further thermal treatments then generate a physical microscale and nanoscale fluidic network inside the dried matrix to allow access to target nucleic acid. The amplification enzymes and primers initiate the reaction within the dried blood matrix through these networks, precluding any need for conventional nucleic acid purification. High heme background is confined to the solid phase, while amplicons are enriched in the clear supernatant (liquid phase), giving fluorescence change comparable to purified DNA reactions. We demonstrate single-molecule sensitivity using a loop-mediated isothermal amplification reaction in our platform and detect a broad spectrum of pathogens, including gram-positive methicillin-resistant and methicillin-susceptible Staphylococcus aureus bacteria, gram-negative Escherichia coli bacteria, and Candida albicans (fungus) from whole blood with a limit of detection (LOD) of 1.2 colony-forming units (CFU)/mL from 0.8 to 1 mL of starting blood volume. We validated our assay using 63 clinical samples (100% sensitivity and specificity) and significantly reduced sample-to-result time from over 20 h to <2.5 h. The reduction in instrumentation complexity and costs compared to blood culture and alternate molecular diagnostic platforms can have broad applications in healthcare systems in developed world and resource-limited settings.
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