In situ conversion of porphyrin microbubbles to nanoparticles for multimodality imaging

• Published in: Nature nanotechnology Vol. 10; no. 4; pp. 325 - 332
• Main Authors: Huynh, Elizabeth, Leung, Ben Y. C., Helfield, Brandon L., Shakiba, Mojdeh, Gandier, Julie-Anne, Jin, Cheng S., Master, Emma R., Wilson, Brian C., Goertz, David E., Zheng, Gang
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.04.2015; Nature Publishing Group
• Subjects: 147/143; 639/925/350/2093; Conversion; Diseases; Drug delivery systems; Image Enhancement - methods; Imaging; letter; Materials Science; Materials Testing; Medical treatment; Microbubbles; Microscopy, Fluorescence - methods; Multimodal Imaging - methods; Nanoparticles; Nanoparticles - chemistry; Nanoparticles - ultrastructure; Nanostructure; Nanotechnology; Nanotechnology and Microengineering; Optical properties; Particle Size; Photoacoustic Techniques - methods; Porphyrins; Porphyrins - chemistry; Porphyrins - radiation effects; Ultrasonography - methods; Ultrasound
• ISSN: 1748-3387; 1748-3395
• DOI: 10.1038/nnano.2015.25

On exposure to low-frequency ultrasound, porphyrin microbubbles form nanoparticles that possess the same optical and therapeutic properties as the original microbubble, which can be used simultaneously for imaging and drug delivery. Converting nanoparticles or monomeric compounds into larger supramolecular structures by endogenous 1 , 2 or external 3 , 4 stimuli is increasingly popular because these materials are useful for imaging and treating diseases. However, conversion of microstructures to nanostructures is less common. Here, we show the conversion of microbubbles to nanoparticles using low-frequency ultrasound. The microbubble consists of a bacteriochlorophyll–lipid shell around a perfluoropropane gas. The encapsulated gas provides ultrasound imaging contrast and the porphyrins in the shell confer photoacoustic and fluorescent properties. On exposure to ultrasound, the microbubbles burst and form smaller nanoparticles that possess the same optical properties as the original microbubble. We show that this conversion is possible in tumour-bearing mice and could be validated using photoacoustic imaging. With this conversion, our microbubble can potentially be used to bypass the enhanced permeability and retention effect when delivering drugs to tumours.