Sensitive biomolecule detection in lateral flow assay with a portable temperature-humidity control device

Lateral flow assays (LFAs) have currently attracted broad interest for point-of-care (POC) diagnostics, but their application has been restricted by poor quantification and limited sensitivity. While the former has been currently solved to some extent by the development of handheld or smartphone-based readers, the latter has not been addressed fully, particularly the potential influences of environmental conditions (e.g., temperature and relative humidity (RH)), which have not yet received serious attention. The present study reports the use of a portable temperature-humidity control device to provide an optimum environmental requirement for sensitivity improvement in LFAs, followed by quantification by using a smartphone. We found that a RH beyond 60% with temperatures of 55-60 °C and 37-40 °C produced optimum nucleic acid hybridization and antigen-antibody interaction in LFAs, respectively representing a 10-fold and 3-fold signal enhancement over ambient conditions (25 °C, 60% RH). We envision that in the future the portable device could be coupled with a fully integrated paper-based sample-to-answer biosensor for sensitive detection of various target analytes in POC settings.