Photoacoustic imaging is a hybrid imaging modality based on the detection of acoustic waves generated by the absorption of short laser pulses in biological tissue, combining the advantages of excellent contrast achieved in optical techniques with the high resolution of ultrasound imaging. Since multi-wavelength photoacoustic imaging can estimate oxygen saturation and total concentration of hemoglobin, it appears a suitable tool for testing the efficacy of new oxygenating drugs in cutaneous hypoxia-associated pathologies, including diabetic foot and bedsores. In the present work, we have developed dextran-shelled, decafluoropentane-containing Oxygen-Loaded Nanobubbles (OLNs), and used photoacoustic imaging to monitor skin oxygenation in the treated mice. Methods. OLN hydroxy-ethylcellulose gel formulations were applied topically on murine hindlimbs. Photoacoustic imaging was performed with commercially available Vevo® LAZR system (Fujifilm VisualSonics) featuring a hybrid ultrasound transducer (central frequency: 21 MHz; spatial resolution: 75 μm). Results. Photoacoustic monitoring revealed significantly and constantly increased oxyHb levels in OLN-treated mice. OLN effects were specifically dependent on O2 gradual diffusion from OLN core, since O2-Free Nanobubbles (OFNs, negative control) did not affect oxy/deoxyHb balances, whereas O2-Saturated Solution (OSS, positive control) did induce a high but only transient oxyHb peak. Conclusions. Photoacoustic imaging appears a useful technique to monitor in vivo skin oxygenation during topical administration of exogenous O2, properly encapsulated in nanobubble formulations. Acknowledgements. Work supported by funding from FujiFilm VisualSonics and Ateneo-Compagnia di San Paolo (ORTO11CE8R 2011).
In vivo photoacoustic imaging of Oxygen-Loaded Nanobubbles: theranostic agents for hypoxia-associated pathologies.
PRATO, Mauro;CAVALLI, Roberta;GUIOT, Caterina
2013-01-01
Abstract
Photoacoustic imaging is a hybrid imaging modality based on the detection of acoustic waves generated by the absorption of short laser pulses in biological tissue, combining the advantages of excellent contrast achieved in optical techniques with the high resolution of ultrasound imaging. Since multi-wavelength photoacoustic imaging can estimate oxygen saturation and total concentration of hemoglobin, it appears a suitable tool for testing the efficacy of new oxygenating drugs in cutaneous hypoxia-associated pathologies, including diabetic foot and bedsores. In the present work, we have developed dextran-shelled, decafluoropentane-containing Oxygen-Loaded Nanobubbles (OLNs), and used photoacoustic imaging to monitor skin oxygenation in the treated mice. Methods. OLN hydroxy-ethylcellulose gel formulations were applied topically on murine hindlimbs. Photoacoustic imaging was performed with commercially available Vevo® LAZR system (Fujifilm VisualSonics) featuring a hybrid ultrasound transducer (central frequency: 21 MHz; spatial resolution: 75 μm). Results. Photoacoustic monitoring revealed significantly and constantly increased oxyHb levels in OLN-treated mice. OLN effects were specifically dependent on O2 gradual diffusion from OLN core, since O2-Free Nanobubbles (OFNs, negative control) did not affect oxy/deoxyHb balances, whereas O2-Saturated Solution (OSS, positive control) did induce a high but only transient oxyHb peak. Conclusions. Photoacoustic imaging appears a useful technique to monitor in vivo skin oxygenation during topical administration of exogenous O2, properly encapsulated in nanobubble formulations. Acknowledgements. Work supported by funding from FujiFilm VisualSonics and Ateneo-Compagnia di San Paolo (ORTO11CE8R 2011).
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