In this study, we present a novel bead-incorporated centrifugal sample pretreatment microdevice to purify
influenza A H3N2
viral RNA. Simple revolution per minute (RPM) control can lead to
RNA capture on a bead-bed, and the sequential loading of a washing
solution and an elution
solution. Tetraethoxy orthosilicate (TEOS)-treated glass
microbeads were utilized as a capture matrix. The sample pretreatment microdevice consists of four reservoirs for storing an
RNA sample, a washing
solution, an elution
solution, and a collected sample, and they were merged at the
microbead-bed microchannel. The washing
solution reservoir and the elution
solution reservoir were connected to the bead-bed microchannel through a capillary valve and a siphon channel, respectively. An
RNA sample (a lysed
influenza A H3N2 virus), a washing
solution (70%
ethanol) and an elution
solution (water or a reverse transcription-polymerase chain reaction (RT-PCR) cocktail) were loaded into the designated reservoirs, and they were successively transported to the bead-bed by RPM control owing to the optimized channel design. Purified RNAs could be obtained in 440 s. Then, a target H3 gene was amplified by an off-chip based real-time RT-PCR to evaluate the capture efficiency of
RNA on our proposed microdevice. 81% of RNAs were successfully captured and purified. Interestingly, the use of the RT-PCR cocktail itself as an elution
solution resulted in a 76% capture yield. Furthermore, we successfully performed
RNA purification from the clinical nasopharyngeal swabs to identify the subtype of the influenza A virus. This platform provides high potential for the direct integration of the sample pretreatment microdevice into the downstream micro-PCR unit to create a total genetic analysis microsystem.