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Edwards RL, Takach JE, McAndrew MJ, Menteer J, Lestz RM, Whitman D, Baxter-Lowe LA. Next generation multiplexing for digital PCR using a novel melt-based hairpin probe design. Front Genet 2023; 14:1272964. [PMID: 38028620 PMCID: PMC10667681 DOI: 10.3389/fgene.2023.1272964] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 10/27/2023] [Indexed: 12/01/2023] Open
Abstract
Digital PCR (dPCR) is a powerful tool for research and diagnostic applications that require absolute quantification of target molecules or detection of rare events, but the number of nucleic acid targets that can be distinguished within an assay has limited its usefulness. For most dPCR systems, one target is detected per optical channel and the total number of targets is limited by the number of optical channels on the platform. Higher-order multiplexing has the potential to dramatically increase the usefulness of dPCR, especially in scenarios with limited sample. Other potential benefits of multiplexing include lower cost, additional information generated by more probes, and higher throughput. To address this unmet need, we developed a novel melt-based hairpin probe design to provide a robust option for multiplexing digital PCR. A prototype multiplex digital PCR (mdPCR) assay using three melt-based hairpin probes per optical channel in a 16-well microfluidic digital PCR platform accurately distinguished and quantified 12 nucleic acid targets per well. For samples with 10,000 human genome equivalents, the probe-specific ranges for limit of blank were 0.00%-0.13%, and those for analytical limit of detection were 0.00%-0.20%. Inter-laboratory reproducibility was excellent (r 2 = 0.997). Importantly, this novel melt-based hairpin probe design has potential to achieve multiplexing beyond the 12 targets/well of this prototype assay. This easy-to-use mdPCR technology with excellent performance characteristics has the potential to revolutionize the use of digital PCR in research and diagnostic settings.
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Affiliation(s)
- Rebecca L. Edwards
- Department of Pathology and Laboratory Medicine, Children’s Hospital Los Angeles, Los Angeles, CA, United States
| | | | | | - Jondavid Menteer
- Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
- Division of Cardiology, Children’s Hospital Los Angeles, Los Angeles, CA, United States
| | - Rachel M. Lestz
- Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
- Division of Nephrology, Children’s Hospital Los Angeles, Los Angeles, CA, United States
| | - Douglas Whitman
- Luminex Corporation, A Diasorin Company, Austin, TX, United States
| | - Lee Ann Baxter-Lowe
- Department of Pathology and Laboratory Medicine, Children’s Hospital Los Angeles, Los Angeles, CA, United States
- Keck School of Medicine, University of Southern California, Los Angeles, CA, United States
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Lai JH, Keum JW, Lee HG, Molaei M, Blair EJ, Li S, Soliman JW, Raol VK, Barker CL, Fodor SPA, Fan HC, Shum EY. New realm of precision multiplexing enabled by massively-parallel single molecule UltraPCR. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.09.561546. [PMID: 37873291 PMCID: PMC10592712 DOI: 10.1101/2023.10.09.561546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/25/2023]
Abstract
PCR has been a reliable and inexpensive method for nucleic acid detection in the past several decades. In particular, multiplex PCR is a powerful tool to analyze many biomarkers in the same reaction, thus maximizing detection sensitivity and reducing sample usage. However, balancing the amplification kinetics between amplicons and distinguishing them can be challenging, diminishing the broad adoption of high order multiplex PCR panels. Here, we present a new paradigm in PCR amplification and multiplexed detection using UltraPCR. UltraPCR utilizes a simple centrifugation workflow to split a PCR reaction into ∼34 million partitions, forming an optically clear pellet of spatially separated reaction compartments in a PCR tube. After in situ thermocycling, light sheet scanning is used to produce a 3D reconstruction of the fluorescent positive compartments within the pellet. At typical sample DNA concentrations, the magnitude of partitions offered by UltraPCR dictate that the vast majority of target molecules occupy a compartment uniquely. This single molecule realm allows for isolated amplification events, thereby eliminating competition between different targets and generating unambiguous optical signals for detection. Using a 4-color optical setup, we demonstrate that we can incorporate 10 different fluorescent dyes in the same UltraPCR reaction. We further push multiplexing to an unprecedented level by combinatorial labeling with fluorescent dyes - referred to as "comboplex" technology. Using the same 4-color optical setup, we developed a 22-target comboplex panel that can detect all targets simultaneously at high precision. Collectively, UltraPCR has the potential to push PCR applications beyond what is currently available, enabling a new class of precision genomics assays.
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Moufarrej MN, Bianchi DW, Shaw GM, Stevenson DK, Quake SR. Noninvasive Prenatal Testing Using Circulating DNA and RNA: Advances, Challenges, and Possibilities. Annu Rev Biomed Data Sci 2023; 6:397-418. [PMID: 37196360 PMCID: PMC10528197 DOI: 10.1146/annurev-biodatasci-020722-094144] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Prenatal screening using sequencing of circulating cell-free DNA has transformed obstetric care over the past decade and significantly reduced the number of invasive diagnostic procedures like amniocentesis for genetic disorders. Nonetheless, emergency care remains the only option for complications like preeclampsia and preterm birth, two of the most prevalent obstetrical syndromes. Advances in noninvasive prenatal testing expand the scope of precision medicine in obstetric care. In this review, we discuss advances, challenges, and possibilities toward the goal of providing proactive, personalized prenatal care. The highlighted advances focus mainly on cell-free nucleic acids; however, we also review research that uses signals from metabolomics, proteomics, intact cells, and the microbiome. We discuss ethical challenges in providing care. Finally, we look to future possibilities, including redefining disease taxonomy and moving from biomarker correlation to biological causation.
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Affiliation(s)
| | - Diana W Bianchi
- Eunice Kennedy Shriver National Institute of Child Health and Human Development and Section on Prenatal Genomics and Fetal Therapy, Center for Precision Health Research, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland, USA
| | - Gary M Shaw
- Department of Pediatrics and March of Dimes Prematurity Research Center at Stanford University, Stanford University School of Medicine, Stanford, California, USA
| | - David K Stevenson
- Department of Pediatrics and March of Dimes Prematurity Research Center at Stanford University, Stanford University School of Medicine, Stanford, California, USA
| | - Stephen R Quake
- Department of Bioengineering and Department of Applied Physics, Stanford University, Stanford, California, USA
- Chan Zuckerberg Initiative, Redwood City, California, USA
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Ma C, Yuan M, Gong P, Zhu H, Tan G. Design of a digital PCR optical detection system with multiple fluorescent microdroplets. APPLIED OPTICS 2023; 62:183-195. [PMID: 36606864 DOI: 10.1364/ao.479774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Accepted: 12/01/2022] [Indexed: 06/17/2023]
Abstract
The need for accurate nucleic acid testing is increasing with the spread of the global pandemic. Problems such as low efficiency and precision and large volume exist because the number of existing digital polymerase chain reaction (PCR) testing instrument channels is low. In order to solve these problems, a four channel micro drop digital PCR system was designed. The collimating lens set and objective lens of the LED light source are designed in ZEMAX software, and the entire optical path is simulated. It is verified that the light energy utilization rate of the system is over 93% and that stray light interference is marginal.
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Shum EY, Lai JH, Li S, Lee HG, Soliman J, Raol VK, Lee CK, Fodor SP, Fan HC. Next-Generation Digital Polymerase Chain Reaction: High-Dynamic-Range Single-Molecule DNA Counting via Ultrapartitioning. Anal Chem 2022; 94:17868-17876. [PMID: 36508568 PMCID: PMC9798378 DOI: 10.1021/acs.analchem.2c03649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Digital PCR (dPCR) was first conceived for single-molecule quantitation. However, current dPCR systems often require DNA templates to share partitions due to limited partitioning capacities. Here, we introduce UltraPCR, a next-generation dPCR system where DNA counting is performed in a single-molecule regimen through a 6-log dynamic range using a swift and parallelized workflow. Each UltraPCR reaction is divided into >30 million partitions without microfluidics to achieve single template occupancy. Combined with a unique emulsion chemistry, partitions are optically clear, enabling the use of a three-dimensional imaging technique to rapidly detect DNA-positive partitions. Single-molecule occupancy also allows for more straightforward multiplex assay development due to the absence of partition-specific competition. As a proof of concept, we developed a 222-plex UltraPCR assay and demonstrated its potential use as a rapid, low-cost screening assay for noninvasive prenatal testing for as low as 4% trisomy fraction samples with high precision, accuracy, and reproducibility.
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Hou Y, Chen S, Zheng Y, Zheng X, Lin JM. Droplet-based digital PCR (ddPCR) and its applications. Trends Analyt Chem 2022. [DOI: 10.1016/j.trac.2022.116897] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Zhu M, Shan Z, Ning W, Wu X. Image Segmentation and Quantification of Droplet dPCR Based on Thermal Bubble Printing Technology. SENSORS (BASEL, SWITZERLAND) 2022; 22:7222. [PMID: 36236321 PMCID: PMC9573249 DOI: 10.3390/s22197222] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/05/2022] [Revised: 09/20/2022] [Accepted: 09/21/2022] [Indexed: 06/16/2023]
Abstract
Thermal inkjet printing can generate more than 300,000 droplets of picoliter scale within one second stably, and the image analysis workflow is used to quantify the positive and negative values of the droplets. In this paper, the SimpleBlobDetector detection algorithm is used to identify and localize droplets with a volume of 24 pL in bright field images and suppress bright spots and scratches when performing droplet location identification. The polynomial surface fitting of the pixel grayscale value of the fluorescence channel image can effectively compensate and correct the image vignetting caused by the optical path, and the compensated fluorescence image can accurately classify positive and negative droplets by the k-means clustering algorithm. 20 µL of the sample solution in the result reading chip can produce more than 100,000 effective droplets. The effective droplet identification correct rate of 20 images of random statistical samples can reach more than 99% and the classification accuracy of positive and negative droplets can reach more than 98% on average. This paper overcomes the problem of effectively classifying positive and negative droplets caused by the poor image quality of photographed picolitre ddPCR droplets caused by optical hardware limitations.
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Affiliation(s)
- Mingjie Zhu
- School of Microelectronics, Shanghai University, Shanghai 200444, China
| | - Zilong Shan
- School of Microelectronics, Shanghai University, Shanghai 200444, China
| | - Wei Ning
- Shanghai Industrial µTechnology Research Institute, Shanghai 201800, China
| | - Xuanye Wu
- School of Microelectronics, Shanghai University, Shanghai 200444, China
- Shanghai Industrial µTechnology Research Institute, Shanghai 201800, China
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