Fig. 4: Detection of SiO2 beads in a homogeneous assay by DIAMOND.
From: Digital plasmonic nanobubble detection for rapid and ultrasensitive virus diagnostics
a Schematic of a homogeneous assay of SiO2 beads by AuNPs as a pair of targets and probes at room temperature (RT). Lower panel shows that when bead concentrations are insufficient to induce the color change, DIAMOND can detect the PNB signals. b TEM image of SiO2-AuNPs conjugates. Scale bar in inset is 200 nm. c Representative PNB signal traces (100 pulses) for the assay solutions. Schematics represent the assay information. d Bivariate plot of amplitude and AUC extracted from 3000 pulses for the assay solutions with different λ of SiO2 beads. Dashed lines indicate the positions of thresholds calculated from the control sample. e Quantification of SiO2 bead concentration and λ(SiO2) as a function of frequency counting (fon). A logistic fitting is applied for the calibration curve. Inset shows the linear region of the calibration curve. The LOD was calculated as 3 standard deviations of the control dividing the slope of regression line. f Linear correlation between the background-subtracted frequency (fon′) and Poisson probability. Error bars in (e) and (f) indicate the standard deviations of three independent measurements.
