High-frequency ultrasound-responsive block copolymer micelle

Area of Science:

• Polymer Chemistry
• Materials Science
• Acoustics

Background:

• Block copolymers form micelles in aqueous solutions.
• Poly(ethylene oxide)-poly(2-tetrahydropyranyl methacrylate) (PEO-b-PTHPMA) micelles are investigated.
• Ultrasound sensitivity in polymer micelles is a developing field.

Purpose of the Study:

• To investigate the disruption of PEO-b-PTHPMA micelles using high-frequency ultrasound.
• To elucidate the mechanism of ultrasound-induced micelle disruption.
• To explore the potential of ultrasound-sensitive block copolymer micelles.

Main Methods:

• Exposure of PEO-b-PTHPMA micellar solutions to high-intensity focused ultrasound (HIFU) at 1.1 MHz.
• Monitoring of pH changes during ultrasound irradiation.
• Characterization using infrared spectroscopy, dynamic light scattering, atomic force microscopy, and fluorescence spectroscopy.

Main Results:

• HIFU induced a decrease in solution pH, indicating hydrolysis of THPMA groups.
• Infrared spectroscopy confirmed the formation of carboxylic acid dimers and hydroxyl groups.
• Micelle disruption was dependent on ultrasound power, solution volume, and focal spot location.

Conclusions:

• High-frequency HIFU can trigger hydrolysis of labile THPMA groups in block copolymer micelles at room temperature.
• This chemical reaction leads to the cleavage of THP groups and subsequent micelle disruption.
• PEO-b-PTHPMA micelles demonstrate ultrasound sensitivity, with potential applications in ultrasound-triggered drug delivery systems.