title: Two-Stage Isothermal Enzymatic Amplification for Concurrent Multiplex Molecular Detection.
abstract: The wide array of pathogens responsible for infectious diseases makes it difficult to identify causative pathogens with single-plex tests. Although multiplex PCR detects multiple targets, it is restricted to centralized laboratories, which delays test results or makes multiplexing unavailable, depriving healthcare providers of critical, real-time information.
  
  
  
  To address the need for point-of-care (POC) highly multiplexed tests, we propose the 2-stage, nested-like, rapid (<40 min) isothermal amplification assay, dubbed rapid amplification (RAMP). RAMP's first-stage uses outer loop-mediated isothermal amplification (LAMP) primers to amplify all targets with recombinase polymerase amplification (RPA). First-stage amplicons are aliquoted to second stage reactors, each specialized for a specific target, to undergo LAMP. The assay is implemented in a microfluidic chip. LAMP amplicons are detected in situ with colorimetric dye or with a fluorescent dye and a smartphone.
  
  
  
  In experiments on a benchtop and in a microfluidic format, RAMP demonstrated high level of multiplexing (≥16); high sensitivity (i.e., 1 plaque-forming unit of Zika virus) and specificity (no false positives or negatives); speed (<40 min); ease of use; and ability to cope with minimally processed samples.
  
  
  
  RAMP is a hybrid, 2-stage, rapid, and highly sensitive and specific assay with extensive multiplexing capabilities, combining the advantages of RPA and LAMP, while circumventing their respective shortcomings. RAMP can be used in the lab, but one of its distinct advantages is amenability to simple implementation in a microfluidic format for use at the POC, providing healthcare personnel with an inexpensive, highly sensitive tool to detect multiple pathogens in a single sample, on site.
authors.affiliation: Department of Mechanical Engineering and Applied Mechanics, School of Engineering and Applied Sciences, University of Pennsylvania, Philadelphia, PA.
authors.forename: Jinzhao
authors.initials: J
authors.lastname: Song
authors.affiliation: Department of Mechanical Engineering and Applied Mechanics, School of Engineering and Applied Sciences, University of Pennsylvania, Philadelphia, PA.
authors.forename: Changchun
authors.initials: C
authors.lastname: Liu
authors.affiliation: Department of Mechanical Engineering and Applied Mechanics, School of Engineering and Applied Sciences, University of Pennsylvania, Philadelphia, PA.
authors.forename: Michael G
authors.initials: MG
authors.lastname: Mauk
authors.affiliation: Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA.
authors.forename: Shelley C
authors.initials: SC
authors.lastname: Rankin
authors.affiliation: Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA.
authors.forename: James B
authors.initials: JB
authors.lastname: Lok
authors.affiliation: Department of Pathobiology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA.
authors.forename: Robert M
authors.initials: RM
authors.lastname: Greenberg
authors.affiliation: Department of Mechanical Engineering and Applied Mechanics, School of Engineering and Applied Sciences, University of Pennsylvania, Philadelphia, PA; bau@seas.upenn.edu.
authors.forename: Haim H
authors.initials: HH
authors.lastname: Bau
mesh_terms: D006801:Humans; D046210:Microfluidic Analytical Techniques; D060885:Multiplex Polymerase Chain Reaction; D021141:Nucleic Acid Amplification Techniques; D019095:Point-of-Care Systems; D013696:Temperature