In vivo imaging of microfluidic-produced microbubbles

Area of Science:

• Biomedical Engineering
• Medical Imaging
• Nanotechnology

Background:

• Microfluidics enables precise microbubble production for medical applications like ultrasound contrast.
• Current methods face limitations in production rate, stability, and diameter control.
• In situ vascular production could overcome these limitations.

Purpose of the Study:

• To investigate the feasibility of in situ microfluidic microbubble production directly within the vasculature.
• To assess the ultrasound contrast enhancement capabilities of these microbubbles in vivo.
• To evaluate the safety and physiological impact of direct vascular administration.

Main Methods:

• Microfluidic device used to generate nitrogen gas microbubbles stabilized with bovine serum albumin and dextrose.
• Microbubbles injected intravenously into wild-type C57BL/6 mice via tail-vein catheter.
• Ultrasound imaging (12.5 MHz) of cardiac ventricles to analyze microbubble transit and image intensity over time.

Main Results:

• Microbubbles produced at rates of approximately 10^5 bubbles/s were observed in both right and left ventricles.
• Median transit times in the right ventricle: 2.9s (rise), 21.3s (duration), 14.3s (decay).
• Mice tolerated the procedure well, with no observable respiratory or cardiac distress, even with microbubbles up to 19 μm.

Conclusions:

• In situ microfluidic microbubble generation in the vasculature is feasible for ultrasound contrast.
• This approach demonstrates potential for simplified in vivo contrast agent administration.
• The method shows promise for applications in diagnostic imaging and potentially drug/gene delivery.