Rapid detection of aflatoxigenic Aspergillus sp. in herbal specimens by a simple, bendable, paper‐based lab‐on‐a‐chip

Postharvest herbal product contamination with mycotoxins and mycotoxin‐producing fungi represents a potentially carcinogenic hazard. Aspergillus flavus is a major cause of this issue. Available mold detection methods are PCR‐based and rely heavily on laboratories; thus, they are unsuitable for on‐site monitoring. In this study, a bendable, paper‐based lab‐on‐a‐chip platform was developed to rapidly detect toxigenic Aspergillus spp. DNA. The 3.0‐4.0 cm 2 chip is fabricated using Whatman™ filter paper, fishing line and a simple plastic lamination process and has nucleic acid amplification and signal detection components. The Aspergillus assay specifically amplifies the aflatoxin biosynthesis gene, a fl R, using loop‐mediated isothermal amplification (LAMP); hybridization between target DNA and probes on blue silvernanoplates (AgNPls) yields colorimetric results. Positive results are indicated by the detection pad appearing blue due to dispersed blue AgNPls; negative results are indicated by the detection pad appearing colorless or pale yellow due to probe/target DNA hybridization and AgNPls aggregation. Assay completion requires less than 40 min, has a limit of detection (LOD) of 100 a fl R copies, and has high specificity (94.47%)and sensitivity (100%). Contamination was identified in 14 of 32 herbal samples tested (43.75%). This work demonstrates the fabrication of a simple, low‐cost, paper‐based lab‐on‐a‐chip platform suitable for rapid‐detection applications.