Figure 4

Colorimetric detection of OHT-GNPs against NA proteins and real viruses. OHT-GNPs were treated with (a) NA proteins (10 μg) and (b) real viruses (103 PFU/test). After 5 min, their absorption profiles were measured using a multidetection microplate reader, and colorimetric changes were observed. The insert photos show the colorimetric changes (black: WT, and red: Tamiflu-resistant). The purple color indicates that OHT-GNPs detected Tamiflu resistance (or the NA protein of the Tamiflu-resistant virus) due to the binding with the Tamiflu-resistant enzyme.