Rapid Transformation of Protein-Caged Nanomaterials into Microbubbles As Bimodal Imaging Agents

We present a general method for converting colloidal nanomaterials into microbubbles as ultrasound contrast agents. Protein-caged nanomaterials, made either by self-assembled nanoparticles' protein corona or by fluorescent gold nanoclusters, can be rapidly transformed into microbubbles via a sonochemical route, which promote disulfide cross-linking of cysteine residues between protein-caged nanomaterials and free albumin during acoustic cavitation. The proposed methods yielded microbubbles with multiple functions by adjusting the original nanoparticle/protein mixture. We also showed a new dual-modal imaging agent of fluorescent gold microbubbles in vitro and in vivo, which can hold many potential applications in medical diagnostics and therapy.