Figure 4a: Fluorescence spectral responses of KF polymeraseaidedamplification assay for HA protein of varying concentrations (a to f: 0, 2.5, 3.5, 5, 7.5, 10 μg/mL). Insert: The linear relationship of the fluorescence intensity on HA protein concentrations from 2.5 μg/mL to 7.5 μg/mL. The error bars embody the standard deviations of repeated results.