Ultrasound Imaging with Bi-Phasic Microbubble Clusters for Drug Retention
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Solution Overview
Problem
Current ultrasound-mediated drug delivery methods using microbubbles face limitations such as low drug loading capacity, high acoustic power requirements, rapid washout, and safety concerns due to cavitation mechanisms, hindering clinical transition.
Innovation Solution
A bi-phasic microbubble/microdroplet formulation where microbubbles are physically attached to emulsion microdroplets prior to administration, forming stable clusters that undergo a liquid-to-gas transition at low ultrasound power, producing large activated bubbles for targeted drug delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If microbubbles are used for ultrasound-mediated drug delivery, then drug delivery to target tissue is enhanced, but drug loading capacity is limited
Solution Approach 1:
The patent combines microbubbles and microdroplets into a single bi-phasic formulation system. The microbubble component provides ultrasound responsiveness while the microdroplet component provides drug loading capacity. This merging allows the system to achieve both enhanced drug delivery and high drug loading capacity without requiring separate complex systems.
Solution Approach 2:
The formulation uses a composite system consisting of two distinct components: gas-filled microbubbles and oil-based microdroplets with dissolved drugs. This composite approach allows each component to contribute its unique properties - the microbubbles for acoustic activation and the microdroplets for high drug payload - thereby resolving the contradiction between drug loading capacity and formulation complexity.
2Productivity
If high acoustic power is applied to activate microbubbles, then drug release is enhanced, but cavitation damage and safety issues increase
Solution Approach 1:
The patent changes the activation parameters by using low acoustic power and low mechanical index (MI < 1.9) ultrasound settings. This parameter change allows activation of the bi-phasic system without reaching the thresholds that cause harmful cavitation. The microdroplet vaporization occurs at lower energy levels compared to traditional microbubble rupture, thereby improving drug release efficiency while minimizing vascular damage.
Solution Approach 2:
The system utilizes phase transition of the microdroplet content from liquid to gas vapor upon ultrasound exposure. This phase transition mechanism occurs at lower acoustic powers than microbubble cavitation, enabling effective drug release without the harmful effects of violent cavitation. The controlled phase change provides a safer activation mechanism that maintains productivity while reducing harmful factors.
3Reliability
If microbubbles are administered for drug delivery, then targeted delivery is improved, but rapid washout from vasculature occurs
Solution Approach 1:
The patent employs preliminary action by having the microdroplet component ready with dissolved drugs before ultrasound activation. The microdroplets are pre-formulated with high drug concentrations and positioned within the vasculature alongside microbubbles. When activated, the immediate vaporization and drug release occur at the target site, ensuring reliable targeted delivery while the pre-positioned formulation prevents rapid washout by maintaining drug presence during the brief vascular transit time.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances drug loading capacity, reduces acoustic power needs, avoids cavitation, and facilitates prolonged drug retention and uptake to target tissues with minimal vascular damage.
Implementation Method 1
the microbubbles and microdroplets of said first and second components have opposite surface charges and form said clusters via attractive electrostatic interactions
Implementation Method 2
activation in-vivo of said cluster composition produces a liquid-to-gas transition (phase shift) of the diffusible component
Implementation Method 3
The clusters are readily activated in-vivo with low power ultrasound (i.e. with an MI of less than 1.9, preferably less than 0.7 and most preferably less than 0.4), which induce a liquid-to-gas transition (phase shift) of the diffusible component
Data Source
AI summary
The present disclosure relates to a method of imaging, involving administration of a bi-phasic formulation followed by application of high frequency sound waves to identify a region of interest. Following identification, a phase shift of the bi-phasic formulation may be activated by a second administration of high frequency sound waves such that gaseous components of the bi-phasic formulation are enlarged and localised at the region of interest.