Figure 5: Detection of deep-tissue infective endocarditis using the SWNT probe.

Comparison of the in-situ bioluminescence (a,b,e,f) from the S. aureus strain Xen-29, with the NIR-II fluorescence from the SWNT probe (c,d,g,h). Also shown are the excised heart and lungs, obtained after euthanizing the animals; Ht: Heart, Lu: Lungs. (a–d) One representative animal is shown from the cohort that received the non-targeted M13-SWNT probe, while (e–h) illustrates an animal from the group that received the targeted anti-S. aureus-M13-SWNT probe, showing high specificity of detection. (i) Intensity enhancement of the fluorescence signal over the RoI, normalized to the control case (naive mice, without suture or bacterial injection, with M13-SWNT dosing). Data plotted as mean±s.d. for N=5 measurements for every set. #, ##, ###P<0.01; statistically significant using Student’s t-test. (j–o) Microscopy analysis of the excised heart tissues, showing bright-field images with Gram staining (j,m,k,n) and fluorescence images using a green dye labelled on the M13 (l,o). Gram staining shows the formation of large vegetations of Gram-positive S. aureus in j and m. Parts of these images, indicated by the red boxes, are shown at × 100 magnification. There is marked enhancement in the fluorescence at the site of bacterial infection for the targeted anti-S. aureus-M13-SWNT-Alexa Fluor 488 case. Scale bar, 100 μm (j,m) and 20 μm (k,l,n,o).