Extended Data Fig. 6: Real-time dynamic NIR-IIb multiplexed imaging of Tm/Er tagged PS beads.

a, Fabrication procedures for polystyrene (PS) beads tagged with both α-TmNPs and α-ErNPs (Tm/Er tagged beads). b, NIR-IIb fluorescence images of Tm/Er-tagged PS beads in Tm-Ch or Er-Ch. The overlapping image shows well co-localization of the two channels. Scale bar, 50 μm. c, A photograph of the simultaneous dual-channel NIR-IIb fluorescence imaging system equipped with a microfluidic system. Tm/Er- tagged PS-beads were dispersed in cetane, followed by being pumped into the flow channel of the glass chip. d, Real-time multiplexed images of Tm/Er-tagged PS beads flowing in the channel of the glass chip at a fixed perfusion rate (100 mL/h). Elongated outline of the PS beads along the direction of fluid flowing was attributed to motion-blur under exposure time of ~ 300 ms. Scale bar, 50 μm. e, Statistical results of the average velocities in the Er-Ch and Tm-Ch. Quantitative results showed mean velocities of PS beads in a range of 4437.7–4657.0 μm/min in Tm-Ch and 4524.3–4675.4 μm/min in Er-Ch, with minor deviation between two imaging channels (less than 2% as shown in the right side of the figure). The data are shown as the mean ± s.d. (n = 17–18). A boxplot with minimum, maximum and median is shown. f, g, Pearson’s correlation (Pr value) analysis of (f) velocity and (g) location of the six tracked PS beads between Er- and Tm-Ch in a, indicating a high spatiotemporal synchronicity.