Photoacoustic delivery and imaging methods in PDT

Homogeneous drug delivery to solid tumors is difficult to achieve because of biological barriers in the tumor and of its elevated interstitial fluid pressure. We investigated the distribution of a photosensitizer (redaporfin) in orthotopic 4T1 and subcutaneous CT26 tumors using photoacoustic tomography. Redaporfin has a distinct photoacoustic spectrum that allows for its localization and relative quantification. Whereas CT26 tumors uptake a large amount of redaporfin, 4T1 tumors have redaporfin mostly in their periphery. We exposed 4T1 tumors to high-intensity, broadband photoacoustic waves and show that the amount of redaporfin in 4T1 tumors increases after 5 minutes of exposure. Photoacoustic waves are a promising non-invasive method to increase drug delivery to solid tumors.