Abstract
The "no reaction" lateral flow assay (nrLFA) uses a simplified LFA structure with no conjugate pad and no stored reagents. In the nrLFA, the capillary-based transport time or distance is the key indicator, rather than the outcome of a biochemical reaction. Hence, the calibration and reproducibility of the nrLFA device are critical. The capillary flow properties of several membrane types (nitrocellulose, nylon, cellulose acetate, polyethersulfone, and polyvinylidene difluoride) are evaluated. Flow rate evaluations of MilliporeSigma Hi-Flow™ Plus (HF075, HF135 and HF180) nitrocellulose membranes on nrLFA are performed using bodily fluids (whole blood, blood plasma, and artificial sweat). The results demonstrate that fluids with lower viscosity travel faster, and membranes with slower flow rate exhibit higher capability to distinguish fluids with different viscosities. Reproducibility tests of nrLFA are performed on HF075, demonstrating excellent reproducibility. The coefficient of variation for blood coagulation tests performed with the nrLFA using induced coagulation was 5% for the plasma front and 2% for the RBC front. The effects of variation in blood hematocrit and sample volume are also reported. The overall results indicate that the nrLFA approach has a high potential to be commercially developed as a blood monitoring point-of-care device with simple calibration capability and excellent reproducibility.