Photoacoustic ratiometric assessment of mitoxantrone release from theranostic ICG-conjugated mesoporous silica nanoparticles.

A theranostic nanosystem based on indocyanine green (ICG) covalently conjugated to mesoporous silica nanoparticles (MSNs) loaded with the anticancer drug mitoxantrone (MTX) is proposed as an innovative photoacoustic probe. Taking advantage of the characteristic PA signal displayed by both ICG and MTX, a PA-ratiometric approach was applied to assess the drug release profile from the MSNs. After complete in vitro characterization of the nanoprobe, a proof-of-concept study has been carried out in tumour-bearing mice to evaluate in vivo its effectiveness for cancer imaging and chemotherapeutic agent delivery.