Comparative visible-light and near-infrared fluorescence detection of microRNA in blood plasma with paper lateral flow test strips

Prevailing colorimetric paper lateral flow strips (PLFSs) are inexpensive and easy to use by untrained personnel, but suffer from low sensitivity and severe interference from complex sample matrices such as blood plasma. Hence, a PLFS based on near-infrared fluorescence (NIRF) has been developed to directly detect microRNA (miRNA) in blood plasma without any further sample pretreatment. To mitigate the issue of low intensity and photo-instability of organic NIRF dye molecules, the dye-encapsulated silica nanoparticles have been synthesized and incorporated into a PLFS for miRNA detection. To demonstrate the advantage of NIRF, a PLFS based on visible-light fluorescence (VisF) has also been constructed as the control. The test results reveal that the NIRF-PLFS with fluorescence emission at 773 nm exhibits sensing performance comparable to the VisF-PLFS with fluorescence emission at 542 nm when measuring miRNA in buffer solution. However, the NIRF-PLFS shows far superior performance over the VisF-PLFS in terms of the linear detection range and the limit of detection when measuring miRNA in blood plasma samples. The NIRF-PLFS has achieved a limit of detection of 50 pM toward miRNA in the diluted blood plasma sample, two orders of magnitude lower than that of the VisF-PLFS. The developed NIRF-PLFS exhibits great potential as a point-of-care (POC) tool in detection of disease biomarkers in human fluid samples.