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  1. Article ; Online: Implementing L-DNA analogs as mirrors of PCR reactant hybridization state: theoretical and practical guidelines for PCR cycle control.

    Spurlock, Nicholas / Gabella, William E / Nelson, Dalton J / Evans, David T / Pask, Megan E / Schmitz, Jonathan E / Haselton, Frederick R

    Analytical methods : advancing methods and applications

    2024  Volume 16, Issue 18, Page(s) 2840–2849

    Abstract: In previous reports, we described a PCR cycle control approach in which the hybridization state of optically labeled L-DNA enantiomers of the D-DNA primers and targets determined when the thermal cycle was switched from cooling to heating and heating to ... ...

    Abstract In previous reports, we described a PCR cycle control approach in which the hybridization state of optically labeled L-DNA enantiomers of the D-DNA primers and targets determined when the thermal cycle was switched from cooling to heating and heating to cooling. A consequence of this approach is that it also "adapts" the cycling conditions to compensate for factors that affect the hybridization kinetics of primers and targets. It assumes, however, that the hybridization state of the labeled L-DNA analogs accurately reflects the hybridization state of the D-DNA primers and targets. In this report, the Van't Hoff equation is applied to determine the L-DNA concentration and ratio of L-DNA strands required by this assumption. Simultaneous fluorescence and temperature measurements were taken during L-DNA controlled cycling, and the optical and thermal switch points compared as a function of both total L-DNA concentration and ratio of strands. Based on the Van't Hoff relationship and these experimental results, L-DNA best mirrors the hybridization of PCR primers and targets when total L-DNA concentration is set equal to the initial concentration of the D-DNA primer of interest. In terms of strand ratios, L-DNA hybridization behavior most closely matches the behavior of their D-DNA counterparts throughout the reaction when one of the L-DNA strands is far in excess of the other. The L-DNA control algorithm was then applied to the practical case of the SARS-CoV-2 N2 reaction, which has been shown to fail or have a delayed Cq when PCR was performed without nucleic acid extraction. PCR Cq values for simulated "unextracted" PCR samples in a nasopharyngeal background and in an NaCl concentration similar to that of viral transport media were determined using either the L-DNA control algorithm (
    MeSH term(s) Polymerase Chain Reaction/methods ; Nucleic Acid Hybridization ; DNA/chemistry ; DNA/analysis ; SARS-CoV-2/genetics ; DNA Primers/chemistry ; COVID-19 ; Humans
    Chemical Substances DNA (9007-49-2) ; DNA Primers
    Language English
    Publishing date 2024-05-09
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2515210-5
    ISSN 1759-9679 ; 1759-9660
    ISSN (online) 1759-9679
    ISSN 1759-9660
    DOI 10.1039/d4ay00083h
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Fluorophore-Quencher Interactions Effect on Hybridization Characteristics of Complementary Oligonucleotides.

    Zimmers, Zackary A / Adams, Nicholas M / Gabella, William E / Haselton, Frederick R

    Analytical methods : advancing methods and applications

    2019  Volume 11, Issue 22, Page(s) 2862–2867

    Abstract: Nucleic acids are often covalently modified with fluorescent reporter molecules to create a hybridization state-dependent optical signal. Designing such a nucleic acid reporter involves selecting a fluorophore, quencher, and fluorescence quenching design. ...

    Abstract Nucleic acids are often covalently modified with fluorescent reporter molecules to create a hybridization state-dependent optical signal. Designing such a nucleic acid reporter involves selecting a fluorophore, quencher, and fluorescence quenching design. This report outlines the effect that these choices have on the DNA hybridization characteristics by examining six fluorophores in four quenching schemes: a quencher molecule offset from the fluorophore by 0, 5, or 10 bases, and nucleotide quenching. The similar binding characteristics of left-handed L-DNA were evaluated in comparison with right-handed DNA to quantify the effect of each quenching scheme. These results were applied to the Adaptive PCR method, which monitors fluorescently-labeled L-DNA as a sentinel for analogous unlabeled D-DNA in the reaction. All of the tested fluorophores and quenching schemes increased the annealing temperature of the oligonucleotide pairs by values ranging from 0.5 to 8.5 °C relative to unlabeled oligonucleotides. The design with the smallest increase (0.5 °C) was a sense strand with a FAM fluorophore and an anti-sense strand with Black Hole Quencher 2 offset by 10 bases from the FAM. An identical design that did not offset the quencher molecules resulted in a shift in annealing temperature of 5 °C. PCR was performed using temperature switching based on each of these L-DNA designs, and efficiency was significantly increased for the 10-base offset design, which had the smallest shift in annealing temperature. These results highlight the importance of selecting an appropriate fluorescence quenching scheme for nucleic acid optical signals.
    Language English
    Publishing date 2019-05-17
    Publishing country England
    Document type Journal Article
    ZDB-ID 2515210-5
    ISSN 1759-9679 ; 1759-9660
    ISSN (online) 1759-9679
    ISSN 1759-9660
    DOI 10.1039/c9ay00584f
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article: Fluorophore-quencher interactions effect on hybridization characteristics of complementary oligonucleotides

    Zimmers, Zackary A / Adams, Nicholas M / Gabella, William E / Haselton, Frederick R

    Analytical methods. 2019 June 6, v. 11, no. 22

    2019  

    Abstract: Nucleic acids are often covalently modified with fluorescent reporter molecules to create a hybridization state-dependent optical signal. Designing such a nucleic acid reporter involves selecting a fluorophore, quencher, and fluorescence quenching design. ...

    Abstract Nucleic acids are often covalently modified with fluorescent reporter molecules to create a hybridization state-dependent optical signal. Designing such a nucleic acid reporter involves selecting a fluorophore, quencher, and fluorescence quenching design. This report outlines the effect that these choices have on the DNA hybridization characteristics by examining six fluorophores in four quenching schemes: a quencher molecule offset from the fluorophore by 0, 5, or 10 bases, and nucleotide quenching. The similar binding characteristics of left-handed L-DNA were evaluated in comparison with right-handed DNA to quantify the effect of each quenching scheme. These results were applied to the Adaptive PCR method, which monitors fluorescently-labeled L-DNA as a sentinel for analogous unlabeled D-DNA in the reaction. All of the tested fluorophores and quenching schemes increased the annealing temperature of the oligonucleotide pairs by values ranging from 0.5 to 8.5 °C relative to unlabeled oligonucleotides. The design with the smallest increase (0.5 °C) was a sense strand with a FAM fluorophore and an anti-sense strand with Black Hole Quencher 2 offset by 10 bases from the FAM. An identical design that did not offset the quencher molecules resulted in a shift in annealing temperature of 5 °C. PCR was performed using temperature switching based on each of these L-DNA designs, and efficiency was significantly increased for the 10-base offset design, which had the smallest shift in annealing temperature. These results highlight the importance of selecting an appropriate fluorescence quenching scheme for nucleic acid optical signals.
    Keywords DNA ; analytical methods ; binding properties ; chemical bonding ; fluorescence ; fluorescent dyes ; hybridization ; nucleic acid annealing ; nucleic acid hybridization ; oligonucleotides ; polymerase chain reaction ; temperature
    Language English
    Dates of publication 2019-0606
    Size p. 2862-2867.
    Publishing place The Royal Society of Chemistry
    Document type Article
    ZDB-ID 2515210-5
    ISSN 1759-9679 ; 1759-9660
    ISSN (online) 1759-9679
    ISSN 1759-9660
    DOI 10.1039/c9ay00584f
    Database NAL-Catalogue (AGRICOLA)

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  4. Article ; Online: Detection of Single-Nucleotide Polymorphism Markers of Antimalarial Drug Resistance Directly from Whole Blood.

    Leelawong, Mindy / Adams, Nicholas M / Gabella, William E / Wright, David W / Haselton, Frederick R

    The Journal of molecular diagnostics : JMD

    2019  Volume 21, Issue 4, Page(s) 623–631

    Abstract: Monitoring of antimalarial resistance is important to prevent its further spread, but the available options for assessing resistance are less than ideal for field settings. Although molecular detection is perhaps the most efficient method, it is also the ...

    Abstract Monitoring of antimalarial resistance is important to prevent its further spread, but the available options for assessing resistance are less than ideal for field settings. Although molecular detection is perhaps the most efficient method, it is also the most complex because it requires DNA extraction and PCR instrumentation. To develop a more deployable approach, we designed new probes, which, when used in combination with an inhibitor-tolerant Taq polymerase, enable single-nucleotide polymorphism genotyping directly from whole blood. The probes feature two strategic design elements: locked nucleic acids to enhance specificity and the reporter dyes Cy5 and TEX615, which have less optical overlap with the blood absorbance spectra than other commonly used dyes. Probe performance was validated on a traditional laboratory-based instrument and then further tested on a field-deployable Adaptive PCR instrument to develop a point-of-care platform appropriate for use in malaria settings. The probes discriminated between wild-type Plasmodium falciparum and the chloroquine-resistant CRT PF3D7_0709000:c.227A>C (p.Lys76Thr) mutant in the presence of 2% blood. Additionally, in allelic discrimination plots with the new probes, samples clustered more closely to their respective axes compared with samples using minor groove binder probes with 6-FAM and VIC reporter dyes. Our strategy greatly simplifies single-nucleotide polymorphism detection and provides a more accessible alternative for antimalarial resistance surveillance in the field.
    MeSH term(s) Alleles ; Antimalarials/pharmacology ; Drug Resistance/genetics ; Genotype ; Humans ; Hydrolysis ; Malaria/diagnosis ; Malaria/drug therapy ; Malaria/genetics ; Malaria/parasitology ; Polymerase Chain Reaction ; Polymorphism, Single Nucleotide
    Chemical Substances Antimalarials
    Language English
    Publishing date 2019-06-13
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 2000060-1
    ISSN 1943-7811 ; 1525-1578
    ISSN (online) 1943-7811
    ISSN 1525-1578
    DOI 10.1016/j.jmoldx.2019.02.004
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Adaptive PCR Based on Hybridization Sensing of Mirror-Image l-DNA.

    Adams, Nicholas M / Gabella, William E / Hardcastle, Austin N / Haselton, Frederick R

    Analytical chemistry

    2016  Volume 89, Issue 1, Page(s) 728–735

    Abstract: Polymerase chain reaction (PCR) is dependent on two key hybridization events during each cycle of amplification, primer annealing and product melting. To ensure that these hybridization events occur, current PCR approaches rely on temperature set points ... ...

    Abstract Polymerase chain reaction (PCR) is dependent on two key hybridization events during each cycle of amplification, primer annealing and product melting. To ensure that these hybridization events occur, current PCR approaches rely on temperature set points and reaction contents that are optimized and maintained using rigid thermal cycling programs and stringent sample preparation procedures. This report describes a fundamentally simpler and more robust PCR design that dynamically controls thermal cycling by more directly monitoring the two key hybridization events during the reaction. This is achieved by optically sensing the annealing and melting of mirror-image l-DNA analogs of the reaction's primers and targets. Because the properties of l-DNA enantiomers parallel those of natural d-DNAs, the l-DNA reagents indicate the cycling conditions required for effective primer annealing and product melting during each cycle without interfering with the reaction. This hybridization-sensing approach adapts in real time to variations in reaction contents and conditions that impact primer annealing and product melting and eliminates the requirement for thermal calibrations and cycling programs. Adaptive PCR is demonstrated to amplify DNA targets with high efficiency and specificity under both controlled conditions and conditions that are known to cause traditional PCR to fail. The advantages of this approach promise to make PCR-based nucleic acid analysis simpler, more robust, and more accessible outside of well-controlled laboratory settings.
    MeSH term(s) DNA/genetics ; DNA Probes/chemistry ; Polymerase Chain Reaction/instrumentation ; Temperature
    Chemical Substances DNA Probes ; DNA (9007-49-2)
    Language English
    Publishing date 2016-12-19
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 1508-8
    ISSN 1520-6882 ; 0003-2700
    ISSN (online) 1520-6882
    ISSN 0003-2700
    DOI 10.1021/acs.analchem.6b03291
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article: Adaptive PCR Based on Hybridization Sensing of Mirror-Image l-DNA

    Adams, Nicholas M / Gabella, William E / Hardcastle, Austin N / Haselton, Frederick R

    Analytical chemistry. 2017 Jan. 03, v. 89, no. 1

    2017  

    Abstract: Polymerase chain reaction (PCR) is dependent on two key hybridization events during each cycle of amplification, primer annealing and product melting. To ensure that these hybridization events occur, current PCR approaches rely on temperature set points ... ...

    Abstract Polymerase chain reaction (PCR) is dependent on two key hybridization events during each cycle of amplification, primer annealing and product melting. To ensure that these hybridization events occur, current PCR approaches rely on temperature set points and reaction contents that are optimized and maintained using rigid thermal cycling programs and stringent sample preparation procedures. This report describes a fundamentally simpler and more robust PCR design that dynamically controls thermal cycling by more directly monitoring the two key hybridization events during the reaction. This is achieved by optically sensing the annealing and melting of mirror-image l-DNA analogs of the reaction’s primers and targets. Because the properties of l-DNA enantiomers parallel those of natural d-DNAs, the l-DNA reagents indicate the cycling conditions required for effective primer annealing and product melting during each cycle without interfering with the reaction. This hybridization-sensing approach adapts in real time to variations in reaction contents and conditions that impact primer annealing and product melting and eliminates the requirement for thermal calibrations and cycling programs. Adaptive PCR is demonstrated to amplify DNA targets with high efficiency and specificity under both controlled conditions and conditions that are known to cause traditional PCR to fail. The advantages of this approach promise to make PCR-based nucleic acid analysis simpler, more robust, and more accessible outside of well-controlled laboratory settings.
    Keywords DNA ; enantiomers ; hybridization ; melting ; monitoring ; nucleic acid annealing ; polymerase chain reaction ; temperature
    Language English
    Dates of publication 2017-0103
    Size p. 728-735.
    Publishing place American Chemical Society
    Document type Article
    ZDB-ID 1508-8
    ISSN 1520-6882 ; 0003-2700
    ISSN (online) 1520-6882
    ISSN 0003-2700
    DOI 10.1021%2Facs.analchem.6b03291
    Database NAL-Catalogue (AGRICOLA)

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  7. Article ; Online: Multiplexed Adaptive RT-PCR Based on L-DNA Hybridization Monitoring for the Detection of Zika, Dengue, and Chikungunya RNA.

    Euliano, Erin M / Hardcastle, Austin N / Victoriano, Christia M / Gabella, William E / Haselton, Frederick R / Adams, Nicholas M

    Scientific reports

    2019  Volume 9, Issue 1, Page(s) 11372

    Abstract: Reverse transcription polymerase chain reaction (RT-PCR) is the gold standard for the molecular diagnosis of many infectious diseases, including RNA viruses, but is generally limited to settings with access to trained personnel and laboratory resources. ... ...

    Abstract Reverse transcription polymerase chain reaction (RT-PCR) is the gold standard for the molecular diagnosis of many infectious diseases, including RNA viruses, but is generally limited to settings with access to trained personnel and laboratory resources. We have previously reported a fundamentally simpler thermal cycling platform called Adaptive PCR, which dynamically controls thermal cycling conditions during each cycle by optically monitoring the annealing and melting of mirror-image L-DNA surrogates of the PCR primers and targets. In this report, we integrate optically-controlled reverse transcription and single-channel monitoring of L-DNAs to develop a multiplexed Adaptive RT-PCR instrument and assay for the detection of Zika, dengue, and chikungunya virus RNA with high target specific and low limits of detection. The assay is demonstrated to detect as low as 5 copies/reaction of Zika or chikungunya RNA and 50 copies/reaction of dengue RNA. The multiplexed Adaptive RT-PCR instrument is robust and has many of the features required to implement diagnostic assays for RNA viruses in settings that lack traditional laboratory resources.
    MeSH term(s) Chikungunya Fever/diagnosis ; Chikungunya virus/isolation & purification ; Chikungunya virus/metabolism ; Dengue/diagnosis ; Dengue Virus/isolation & purification ; Dengue Virus/metabolism ; Humans ; Multiplex Polymerase Chain Reaction/methods ; RNA, Viral/analysis ; Reverse Transcriptase Polymerase Chain Reaction/methods ; Sensitivity and Specificity ; Zika Virus/isolation & purification ; Zika Virus/metabolism ; Zika Virus Infection/diagnosis
    Chemical Substances RNA, Viral
    Language English
    Publishing date 2019-08-06
    Publishing country England
    Document type Journal Article ; Research Support, N.I.H., Extramural
    ZDB-ID 2615211-3
    ISSN 2045-2322 ; 2045-2322
    ISSN (online) 2045-2322
    ISSN 2045-2322
    DOI 10.1038/s41598-019-47862-6
    Database MEDical Literature Analysis and Retrieval System OnLINE

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