A Foldable Thermoplastic Microdevice Integrating Isothermal Amplification and Schiff-Reaction-Based Colorimetric Assay for the Detection of Infectious Pathogens

Abstract

In this study, we introduce a plastic-based foldable microdevice that integrates loop-mediated isothermal amplification (LAMP) and a colorimetric assay based on the Schiff reaction to detect the genes of infectious bacteria. The device comprises two sides: a sample zone containing amplification chambers and a detection zone for the colorimetric assay. The detection zone contains poly(methyl methacrylate) structures for transferring the colorimetric reagent-soaked glass micro-fiber paper into the sample chambers. Specific genes of Staphylococcus aureus (S. aureus) and Streptococcus pneumoniae (S. pneumoniae), the most common bacterial infection causes, were amplified by LAMP assay. The S. aureus gene was detected up to 10 fg/μL and the S. pneumoniae gene up to 0.1 pg/μL. The amplified target genes were visually identified using a colorimetric assay with Schiff’s reagent, which showed clear color discrimination through a reaction with aldehyde groups derived from the DNA in the amplicons. The introduced method, integrating amplification and detection processes in a single device, is expected to be utilized in point-of-care testing analysis for the simple and rapid detection of infectious pathogens.