We introduce a portable biochemical
analysis platform for rapid
field deployment of nucleic acid-based diagnostics using consumer-class
quadcopter drones. This approach exploits the ability to isothermally
perform the polymerase chain reaction (PCR) with a single heater,
enabling the system to be operated using standard 5 V USB sources
that power mobile devices (via battery, solar, or hand crank action).
Time-resolved fluorescence detection and quantification is achieved
using a smartphone camera and integrated image analysis app. Standard
sample preparation is enabled by leveraging the drone’s motors
as centrifuges via 3D printed snap-on attachments. These advancements
make it possible to build a complete DNA/RNA analysis system at a
cost of ∼$50 ($US). Our instrument is rugged and versatile,
enabling pinpoint deployment of sophisticated diagnostics to distributed
field sites. This capability is demonstrated by successful in-flight
replication of Staphylococcus aureus and λ-phage
DNA targets in under 20 min. The ability to perform rapid in-flight
assays with smartphone connectivity eliminates delays between sample
collection and analysis so that test results can be delivered in minutes,
suggesting new possibilities for drone-based systems to function in
broader and more sophisticated roles beyond cargo transport and imaging.
Most molecular diagnostic assays require upfront sample preparation steps to isolate the target’s nucleic acids, followed by its amplification and detection using various nucleic acid amplification techniques. Because molecular diagnostic methods are generally rather difficult to perform manually without highly trained users, automated and integrated systems are highly desirable but too costly for use at point-of-care or low-resource settings. Here, we showcase the development of a low-cost and rapid nucleic acid isolation and amplification platform by modifying entry-level 3D printers that cost between $400 and $750. Our modifications consisted of replacing the extruder with a tip-comb attachment that houses magnets to conduct magnetic particle-based nucleic acid extraction. We then programmed the 3D printer to conduct motions that can perform high-quality extraction protocols. Up to 12 samples can be processed simultaneously in under 13 minutes and the efficiency of nucleic acid isolation matches well against gold-standard spin-column-based extraction technology. Additionally, we used the 3D printer’s heated bed to supply heat to perform water bath-based polymerase chain reactions (PCRs). Using another attachment to hold PCR tubes, the 3D printer was programmed to automate the process of shuttling PCR tubes between water baths. By eliminating the temperature ramping needed in most commercial thermal cyclers, the run time of a 35-cycle PCR protocol was shortened by 33%. This article demonstrates that for applications in resource-limited settings, expensive nucleic acid extraction devices and thermal cyclers that are used in many central laboratories can be potentially replaced by a device modified from inexpensive entry-level 3D printers.
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.