This work shows that loop-mediated isothermal amplification (LAMP) of nucleic acid can be integrated in an eight-channel microfluidic chip for readout either by the naked eye (as a result of the insoluble byproduct pyrophosphate generating during LAMP amplification) or via absorbance measured by an optic sensor; we call this system microLAMP (microLAMP). It is capable of analyzing target nucleic acids quantitatively with high sensitivity and specificity. The assay is straightforward in manipulation. It requires a sample volume of 0.4 microL and is complete within 1 h. The sensitivity of the assay is comparable to standard methods, where 10 fg of DNA sample could be detected under isothermal conditions (63 degrees C). A real time quantitative microLAMP assay using absorbance detection is possible by integration of optical fibers within the chip.

Multiplex gene assay is a valuable molecular tool not only in academic science but also in clinical diagnostics. Multiplex PCR assays, DNA microarrays, and various nanotechnology-based methods are examples of major techniques developed for analyzing multiple genes; none of these, however, are suitable for point-of-care diagnostics, especially in resource-limited settings. In this report, we describe an octopus-like multiplex microfluidic loop-mediated isothermal amplification (mμLAMP) assay for the rapid analysis of multiple genes in the point-of-care format and provide a robust approach for predicting viruses. This assay with the ability of analyzing multiple genes qualitatively and quantitatively is highly specific, operationally simple, and cost/time-effective with the detection limit of less than 10 copies/μL in 2 μL quantities of sample within 0.5 h. We successfully developed a mμLAMP chip for differentiating three human influenza A substrains and identifying eight important swine viruses.

Interstitial fluid (ISF), as an emerging source of biomarkers, is unmistakably significant for disease diagnosis. Microneedles (MNs) provide a minimally invasive approach for extracting the desired molecules from ISF. However, existing MNs are limited by their capture efficiency and sensitivity, which impedes early disease diagnosis. Herein, an engineered wearable epidermal system is presented with a combination of reverse iontophoresis and MNs for rapid capture and sensing of Epstein‐Barr virus cell‐free DNA (an important biomarker of nasopharyngeal carcinoma). Owing to a dual‐extraction effect demonstrated by reverse iontophoresis and MNs, the engineered wearable platform successfully isolates the cell‐free DNA target from ISF within 10 min, with a threshold of 5 copies per µL and a maximum capture efficiency of 95.4%. The captured cell‐free DNA is also directly used in a recombinase polymerase amplification electrochemical microfluidic biosensor with a detection limit of 1.1 copies per µL (or a single copy). The experimental data from immunodeficient mouse models rationalizes the feasibility and practicality of the wearable system. Collectively, the developed method opens an innovative route for minimally invasive sampling of ISF for cell‐free DNA‐related cancer screening and prognosis.