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.
In the present work we show that the interaction between short lasers pulses and tailor-made nanostrucured materials can produce broadband high-frequency ultrasound. In order to obtain efficient light-to-pressure conversion we used nanostructured carbon nanotubes permeated with high thermal expansion polydimethylsiloxane and nanometric TiO2 particles with adsorbed dye infused polystyrene. It is possible to achieve ultrasound pulses with central frequencies of 80 MHz and bandwidths of 125 MHz (at -6 dB) using a 6 ns pulsed laser. The aforementioned materials are used in order to establish proof-of-concept of the non-destructive ultrasound pulses interaction with biological membranes, exemplified by the unloading of Green Fluorescence Protein from giant unilamellar vesicles, and of non-invasive material inspection, illustrated with the measurement of the thickness of thin paint layers based on ultrasound frequency attenuation.
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