Limiting dilution PCR has become an increasingly useful technique for the detection and quantification of rare species in a population, but the limit of detection and accuracy of quantification are largely determined by the number of reactions that can be analyzed. Increased throughput may be achieved by reducing the reaction volume and increasing processivity. We have designed a high-throughput microfluidic chip that encapsulates PCR reagents in millions of picoliter droplets in a continuous oil flow. The oil stream conducts the droplets through alternating denaturation and annealing zones, resulting in rapid (55 second cycles) and efficient PCR amplification. Inclusion of fluorescent probes in the PCR reaction mix permits the amplification process to be monitored within individual droplets at specific locations within the microfluidic chip. We show that amplification of a 245 bp Adenovirus product can be detected and quantified in 35 minutes at starting template concentrations as low as one template molecule per 167 droplets (0.003 pg/μL). The frequencies of positive reactions over a range of template concentrations agree closely with the frequencies predicted by Poisson statistics, demonstrating both the accuracy and sensitivity of this platform for limiting dilution and digital PCR applications.
GaP tensile strain compensation (SC) layers were introduced into GaAs solar cells enhanced with a five layer stack of InAs quantum dots (QDs). One sun air mass zero illuminated current-voltage curves show that SC results in improved conversion efficiency and reduced dark current. The strain compensated QD solar cell shows a slight increase in short circuit current compared to a baseline GaAs cell due to sub-GaAs bandgap absorption by the InAs QD. Quantum efficiency and electroluminescence were also measured and provide further insight to the improvements due to SC.
RECEIVED DATE (to be automatically inserted after your manuscript is accepted if required according to the journal that you are submitting your paper to) *beer2@llnl.gov ABSTRACT. The first lab-on-chip system for picoliter droplet generation and RNA isolation, followed by reverse transcription, and PCR amplification with real-time fluorescence detection in the trapped droplets has been developed. The system utilized a shearing T-junction in a fused silica device to generate a stream of monodisperse picoliter-scale droplets that were isolated from the microfluidic channel walls and each other by the oil phase carrier. An off-chip valving system stopped the droplets on-chip, allowing thermal cycling for reverse transcription and subsequent PCR amplification without droplet motion. This combination of the established realtime reverse transcription-PCR assay with digital microfluidics is ideal for isolating single-copy RNA and virions from a complex environment, and will be useful in viral discovery and geneprofiling applications.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.