The field of acoustic droplet vaporization (ADV) was introduced nearly 20 years ago to embolize tissues non-invasively. ADV used 1-5 µm perfluorocarbon (PFC) droplets and converted them into large gas bodies in the feeding artery with ultrasound (US) to embolize tissues downstream. Despite its potential clinical impact, the ADV field has not advanced. The manufacture of nanodroplets (ND) using PFC that boils near 0 oC to facilitate vaporization, was introduced 10 years later to rescue ADV, and to capitalize on the extravasation of small size ND for tumor detection. Despite this advance, the field remains stagnant because of critical efficacy and safety challenges hindering its translation and widespread use. The important challenge is the energetics required to cavitate the liquid PFC into gas, and the resultant rapid expansion that could injure tissues. We recently discovered and confirmed in vitro that when liquid PFC NDs come in close proximity to PFC gas-filled nanobubbles (NBs) or microbubbles (MB), liquid PFC evaporates from droplets to nearby bubbles and the fusion of their shell components results in bubble volume expansion by up to 6 orders of magnitude. Our platform departs from the status quo to achieve the benefits of ADV but without US nor the energetics required for vaporization. Our goal is to translate this approach to occlude tumor vessels from inside out, and do so without the need to visualize tumors since no US activation is needed. Equally exciting, the ability to control microbubble inflation to a specific size will enable diagnostic applications without the potentially harmful side effect of occluding vital vessels.

Nanodroplet vaporization without ultrasound as a new theranostic platform

ACS Spring Meeting 2021

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