Fig. 4.

Contrast-enhanced OCT imaging of retinal vessels after intravenous ${\mathrm{GNR}}^{\mathrm{mPEG}}$ injection. (a) Experimental design. Orange arrows indicate the time points for IV injection of ${\mathrm{GNR}}^{\mathrm{mPEG}}$. Black arrows indicate the times at which OCT imaging was performed. (b) Representative OCT images of mice retinae before and after ${\mathrm{GNR}}^{\mathrm{mPEG}}$ injection. Conditions corresponding to the images are indicated on the left. $\text{Scale bar}=500\mu \mathrm{m}$. (c) and (d) Measure of OCT intensity inside retinal blood vessels after ${\mathrm{GNR}}^{\mathrm{mPEG}}$ injection. (c) Sensitivity measurements and (d) measure of ${\mathrm{GNR}}^{\mathrm{mPEG}}$ signal decay from blood postinjection. $\text{Mean}\pm \mathrm{SEM}$; * $p$ value $<0.05$, $\mathrm{ns}=\text{not significant}$; all conditions in (c) and (d) are compared with preinjection images using one-way analysis of variance. Data represent three independent experiments. (e) Hyperspectral image of unstained $5\text{-}\mu \mathrm{m}$-thick formalin-fixed paraffin embedded section of a mouse retina 1 h after IV injection of ${\mathrm{GNR}}^{\mathrm{mPEG}}$. Gray—ambient scattering from tissue, red—pixels with characteristic spectra from GNRs. $\text{Scale bar}=50\mu \mathrm{m}$. Note the presence of GNRs inside a large vessel at the center.