In the current work, we established in vivo imaging of antigen-specific CD8+ CTLs in the tumour microenvironment induced by the pErNP–OVA–CpG B nanovaccine targeted to the tumour draining lymph node, using two additional NIR-IIb emitting nanoparticles functionalized with the same P3 coating (as the pErNP vaccine carrier) and conjugated to CD8 diabody and pMHC-I OVA–tetramer, respectively (Fig. 4a). Here, CD8A is linked to neoplasm.