A new contrast agent for combined photoacoustic and ultrasound imaging is presented. It has a liquid perfluorocarbon (PFC) core of about 250 nm diameter coated by a 30 nm thin polypyrrole (PPy) doped polymer shell emulsion that represents a broadband absorber covering the visible and near-infrared ranges (peak optical extinction at 1050 nm). When exposed to a sufficiently high intensity optical or acoustic pulse, the droplets vaporize to form microbubbles providing a strong increase in imaging sensitivity and specificity. The threshold for contrast agent activation can further drastically be reduced by up to 2 orders of magnitude if simultaneously exposing them with optical and acoustic pulses. The selection of PFC core liquids with low boiling points (i.e., perfluorohexane (56 °C), perfluoropentane (29 °C), and perfluorobutane (−2 °C)) facilitates activation and reduces the activation threshold of PPy-coated emulsion contrast agents to levels well within clinical safety limits (as low as 0.2 MPa at 1 mJ/cm²). Finally, the potential use of these nanoemulsions as a contrast agent is demonstrated in a series of phantom imaging studies.

中文翻译：

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聚吡咯涂层全氟化碳纳米乳剂作为声光声对比剂

提出了一种用于光声和超声成像相结合的新型造影剂。它具有直径约250 nm的液态全氟化碳（PFC）核，并涂覆有30 nm的稀聚吡咯（PPy）掺杂的聚合物壳乳液，代表了覆盖可见光和近红外范围（1050 nm的峰值消光）的宽带吸收剂。当暴露于足够高强度的光或声脉冲时，液滴蒸发形成微气泡，从而大大提高了成像灵敏度和特异性。如果同时将造影剂暴露于光和声脉冲中，则可以进一步将造影剂激活的阈值大幅降低2个数量级。选择低沸点的PFC核心液体（例如，全氟己烷（56°C），全氟戊烷（29°C），²）。最后，在一系列幻像成像研究中证明了这些纳米乳剂作为造影剂的潜在用途。