Simple, low-cost, and accurate nucleic acid assay platforms
hold
great promise for point-of-care (POC) pathogen detection, disease
surveillance, and control. Plasmonic photothermal polymerase chain
reaction (PPT-PCR) is a powerful and efficient nucleic acid amplification
technique, but it lacks a simple and convenient analysis method for
POC applications. Herein, we propose a novel plasmonic cross-linking
colorimetric PCR (PPT-ccPCR) assay by integrating plasmonic magnetic
nanoparticle (PMN)-based PPT-PCR with gold nanoparticle (AuNP)-based
cross-linking colorimetry. AuNPs form assembled structures with the
PMNs in the presence of amplicons and collect in a magnetic field,
resulting in color changes to the supernatant. Target DNA with concentrations
as low as 5 copies/μL can be visually detected within 40 min.
The achieved limit of detection was 1.8 copies/μL based on the
absorption signals. This simple and sensitive strategy needs no expensive
instrumentation and demonstrates high potential for POC detection
while enabling further applications in clinical diagnostics.