A New Theranostic System Based on Gold Nanocages and Phase-Change Materials with Unique Features for Photoacoustic Imaging and Controlled Release

TLDR

The authors present a theranostic platform that simultaneously boosts photoacoustic imaging contrast and enables ultrasound‑triggered release of therapeutic agents. The platform is fabricated by loading gold nanocages with a phase‑change material such as 1‑tetradecanol, which can be pre‑mixed with dyes or effectors and, upon heating or HIFU, melts and diffuses through surface pores to release the encapsulated payload. Release kinetics are tunable by adjusting HIFU power, exposure time, or both, allowing precise control over the effector release profile.

Abstract

This communication reports a new theranostic system with a combination of capabilities to both enhance the contrast of photoacoustic (PA) imaging and control the release of a chemical or biological effector by high-intensity focused ultrasound (HIFU). The fabrication of this system simply involves filling the hollow interiors of gold nanocages with a phase-change material (PCM) such as 1-tetradecanol that has a melting point of 38−39 °C. The PCM can be premixed and thus loaded with a dye, as well as other chemical or biological effectors. When exposed to direct heating or HIFU, the PCM will melt and escape from the interiors of nanocages through small pores on the surface, concurrently releasing the encapsulated molecules into the surrounding medium. We can control the release profile by varying the power of HIFU, the duration of exposure to HIFU, or both.