Loop-mediated isothermal amplification of a single DNA molecule in polyacrylamide gel-based microchamber
Loop-mediated isothermal amplification (LAMP) is an original nucleic acid amplification method established by Notomi et al. LAMP is performed under isothermal condition, employing only a basic reaction protocol and minimal supporting electronics. These requirements prove to be viable for exploring the avenues to down-scale this biological reaction for Lab-on-a-chip application. Hence here, we developed a novel technique for fluorescent imaging of LAMP at a single molecule level. The experiment was conducted in a polyacrylamide (PAA) gel-based microchamber where a single DNA template, freely suspended in a solution containing primers and polymerase was initially encapsulated. In order to activate the amplification reaction, a microheater regulated by an automatic computerized feedback system was used for localized heating. This microchamber-based approach for LAMP demonstrated the effective exploitation of minute amount of templates and primers, and the overall reduction in LAMP detection time. An average efficiency of 80% was evaluated for conducting DNA amplification after 50 min of incubation at 65°C. As the total time for reaction including detection can be completed in less than 1 h, this one-step, direct observation method displays the potential as a simple alternative to conventional techniques for genetic analysis and diagnosis in the clinical laboratory.