Validation of a fluorescence-based method for the quantitative detection of specific nucleic acids aboard the ISS

The ability to detect and quantify specific nucleic acids is crucial for applications such as genetic research and real-time diagnostics. Polymerase chain reaction (PCR) and quantitative PCR (qPCR) are commonly used to detect DNA. However, these techniques are limited on-orbit due to the size and complexity of the equipment. To address these challenges, we have developed and characterized an alternative to qPCR, called fluoPCR, for use in spaceflight. The fluoPCR workflow consists of 1) a miniaturized thermal cycler to amplify target DNA sequences, 2) a handheld fluorescence viewer for optical detection of amplicons, and 3) data analysis to quantify fluorescence intensity. We tested the fluoPCR assay on the ISS across a range of target DNA sequence sizes and amounts. We found that targeted 100- and 400-base-pair (bp) sequences could be detected with high specificity and with quantifiable data patterns consistent with those obtained from ground qPCR assays. This investigation validates fluoPCR as a versatile alternative to qPCR for detecting and quantifying specific DNA sequences. It can be performed entirely aboard the ISS and similar space habitats and may enable quantitative nucleic acid detection for applications, from genetic research to molecular diagnostics, both in space and in resource-limited settings on Earth.