Nanobody-photosensitizer conjugates for targeted photodynamic therapy

Conjugates consisting of nanobodies (NB) targeting the epidermal growth factor receptor (EGFR) and a traceable photosensitizer (PS) are here described and evaluated in vitro. EGFR-targeted NB-PS conjugates retain their binding specificity after PS conjugation and the biparatopic NB leads to a more effective intracellular delivery of PS. These NB-PS conjugates specifically induce cell death of EGFR overexpressing cells, in the low nanomolar concentration, while PS alone or the NB-PS conjugates in the absence of light induce no toxicity. These new NB-PS conjugates are promising in the field of targeted photodynamic therapy (PDT).212