Remote Loading: The Missing Piece for Achieving High Drug Payload and Rapid Release in Polymeric Microbubbles

Area of Science:

• Biomedical Engineering
• Materials Science
• Nanotechnology

Background:

• Microbubbles are used for targeted drug delivery, but suffer from limited drug loading capacity.
• Current methods involve surface loading or nanoparticle coating, restricting payload.
• A new approach is needed to significantly increase drug loading for improved therapeutic efficacy.

Purpose of the Study:

• To develop a novel method for significantly increasing drug loading capacity in microbubbles.
• To create remotely loaded microbubbles (RLMBs) with a high payload of doxorubicin.
• To demonstrate on-demand drug release from RLMBs using an external stimulus.

Main Methods:

• Utilized a transmembrane ammonium sulfate and pH gradient for crystallized doxorubicin loading into polymeric microcapsules.
• Created RLMBs by sublimating the liquid core of the doxorubicin-loaded microcapsules.
• Investigated doxorubicin release kinetics from RLMBs under ultrasound exposure.

Main Results:

• Achieved an 18-fold increase in drug payload in RLMBs compared to physically loaded microcapsules.
• Demonstrated rapid and efficient drug release: 82.4 ± 5.5% doxorubicin released within 120 seconds.
• Successfully developed microbubbles capable of releasing drugs from the core on demand.

Conclusions:

• This novel technique significantly enhances drug loading capacity for microbubble-based drug delivery.
• Remotely loaded microbubbles offer a promising platform for targeted cancer therapy with on-demand drug release.
• The developed RLMBs represent a breakthrough in microbubble technology for advanced drug delivery applications.