Hypothesis: The development of drug delivery systems with high-dose capability and remote control is of great importance in the field of medicine These systems show significant potential in improving therapeutic efficacy by increasing drug half-life and stability, optimizing drug dosage, and reducing side effects. Microbubbles (MBs) have been introduced as novel imaging agents and ultrasound-responsive drug carriers. These structures, consisting of a gas core enclosed in a shell, have the ability to deliver drugs in a targeted manner to the desired tissue These unique features have made microbubbles a promising option for theranostic applications Methods: In this research, an ultrasound-responsive drug carrier was developed through the synthesis of microbubbles with a polymeric shell made of block copolymer poly(ethylene glycol) and polycaprolactone (PEG-b-PCL) and a perfluorohexane (PFH) core, capable of releasing its contents in response to ultrasound and temperature stimuli. The diblock copolymer PEG-b-PCL is biodegradable, biocompatible amphiphilic, and at the same time, its polymerization method is relatively simple.
Findings: Optical microscopy results showed that the synthesized nanodroplets (NDs) are spherical and respond well to ultrasound. The stability of the particles and their size distribution were examined by dynamic light scattering (DLS). Finally doxorubicin hydrochloride (DOX), as a model drug, was successfully loaded onto the particles, achieving encapsulation efficiencies of 98.4% for the shell, where the drug was predominantly confined, and 95.84% for the particles, reflecting an overall high loading capacity throughout the structure. Additionally, drug release and its responsiveness to ultrasound were investigated. The results indicated that the particles were ultrasound-responsive, and drug release increased significantly during ultrasound exposure, making this drug carrier an ideal candidate for use as a theranostic agent in cancer treatment.