Integrating nucleic acid extraction in amplification-based
point-of-care
diagnostics will be a significant feature for next-generation point-of-care
virus detection devices. However, extracting DNA efficiently on a
microfluidic chip poses many technological and commercialization challenges,
including manual steps, multiple instruments, pretreatment processes,
and the use of organic solvents (ethanol, IPA) that inhibit detection,
which is not viable with routine testing such as viral load monitoring
of transplant patients for post-operative care. This paper presents
a microfluidic system capable of two-step DNA extraction from blood
using a UV-assisted hyperbranched poly(β-amino ester) (HPAE)-modified
silica membrane for cytomegalovirus (CMV) detection in a rapid and
instrument-free manner without the presence of amplification inhibitors.
HPAEs of varying branch ratios were synthesized, screened, and coated
on a silica membrane and bonded between two layers of poly(methyl
methacrylate) (PMMA) substrates. Our system could selectively extract
DNA from blood with an efficiency of 94% and a lower limit viral load
of 300 IU/mL in 20 min. The extracted DNA was used as the template
for real-time loop-mediated isothermal amplification (LAMP)-based
detection of CMV and was found to produce a fluorescent signal intensity
that was comparable with commercially extracted templates. This system
can be integrated easily with a nucleic acid amplification system
and used for routine rapid testing of viral load in patient blood
samples.