Figure 5.
Magnetic enrichment of fluorescent-streptavidin by AuNP/mNP mixtures. AF-750 labeled-streptavidin fluorescence and AuNP absorbance were measured after processing variable volumes of 50% human plasma containing 5 nM fluorescent-streptavidin. In all cases, the captured particles were redissolved into 10 μL of PBS 6.0 buffer, achieving a 50-fold, 25-fold, or 10-fold particle/protein enrichment factor for the 500, 250, and 100 μL samples, respectively. Samples spiked with 1 μM free biotin served as negative controls to block the streptavidin binding sites preventing fluorescence capture, while particle capture/absorbance remained high.