Objectives. Dextran-shelled, decafluoropentane-containing Oxygen-Loaded Nanobubbles (OLNs), ~500 nm-sized and negatively charged, are new oxygenating drugs developed to treat hypoxia-associated pathologies, including cutaneous chronic wounds (diabetic foot, bedsores). In the present work, O2 saturation and haemoglobin (Hb) total concentration were monitored in OLN-treated mice by photoacoustic imaging, a hybrid technique based on detection of acoustic waves generated by absorption of short laser pulses in biological tissues, combining excellent contrast from optical techniques with high resolution from ultrasound imaging. Methods. OLN hydroxy-ethylcellulose gel formulations were applied topically on murine hindlimbs. Photoacoustic imaging was performed with commercially available Vevo® LAZR system (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. Apparently, 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.
In vivo photoacoustic imaging and Oxygen-Loaded Nanobubbles: a meant-to-be marriage for cutaneous oxygenation improvement.
PRATO, Mauro;GUIOT, Caterina
2013-01-01
Abstract
Objectives. Dextran-shelled, decafluoropentane-containing Oxygen-Loaded Nanobubbles (OLNs), ~500 nm-sized and negatively charged, are new oxygenating drugs developed to treat hypoxia-associated pathologies, including cutaneous chronic wounds (diabetic foot, bedsores). In the present work, O2 saturation and haemoglobin (Hb) total concentration were monitored in OLN-treated mice by photoacoustic imaging, a hybrid technique based on detection of acoustic waves generated by absorption of short laser pulses in biological tissues, combining excellent contrast from optical techniques with high resolution from ultrasound imaging. Methods. OLN hydroxy-ethylcellulose gel formulations were applied topically on murine hindlimbs. Photoacoustic imaging was performed with commercially available Vevo® LAZR system (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. Apparently, 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.
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