Real-time monitoring of NIR-triggered drug release from phase-changeable nanodroplets by photoacoustic/ultrasound imaging

Optical-responsive nanodroplets have recently been studied as a new mode of remotely controlled drug delivery. As a class of new emerging smart drug carriers, NIR-absorber-loaded perfluorocarbon nanodroplets can be converted into gas bubbles through laser stimulation, called optical droplet vaporization (ODV), which provides a potential strategy to deliver therapeutic agents to solid tumors on demand. However, there is a lack of suitable technologies to monitor these drug-loaded nanodroplet behaviors in vivo, and control the site and amount of drug released. In this study, ultrasound and photoacoustic imaging technology were applied to directly monitor optical-responsive, drug-loaded nanodroplets within the tissue. We explored the effects of laser energy, repetition rate, and number of pulses on the release profiles of the delivered drug as well as ultrasound and photoacoustic imaging signal-intensity curves. The conducted studies demonstrated that this noninvasive technology helped determine the optimum time point for laser activation on accumulated drug-loaded nanodroplets within tissues, allowing for the potential to effectively treat pathologies while minimizing drug-related toxicities.

Automated summary

Optical-responsive nanodroplets are investigated as a new mode of remotely controlled drug delivery. NIR-absorber-loaded perfluorocarbon nanodroplets can be converted into gas bubbles through laser stimulation, known as optical droplet vaporization (ODV), providing a potential strategy to deliver therapeutic agents to solid tumors on demand. This study applies ultrasound and photoacoustic imaging technology to directly monitor drug-loaded nanodroplets in tissue, enabling the control of drug release and determining the optimal time point for laser activation.