Evaluation of 18F-labeled targeted perfluorocarbon-filled albumin microbubbles as a probe for microUS and microPET in tumor-bearing mice

ObjectiveIn this study, albumin-shelled, targeted MBs (tMBs) were first demonstrated with the expectation of visualization of biodistribution of albumin-shelled tMBs. The actual biodistribution of albumin-shelled tMBs is of vital importance either for molecular imaging or for drug delivery.MotivationRecently, albumin microbubbles (MBs) have been studied for drug and gene delivery in vitro and in vivo through cavitation. Targeted lipid-shelled MBs have been applied for ultrasound molecular imaging and conjugated with radiolabeled antibodies for whole-body biodistribution evaluations. The novelty of the work is that, in addition to the lipid tMBs, the albumin tMBs was also applied in biodistribution detection.MethodsMultimodality albumin-shelled, 18F-SFB-labeled VEGFR2 tMBs were synthesized, and their characteristics in mice bearing MDA-MB-231 human breast cancer were investigated with micro-positron-emission tomography (microPET) and high-frequency ultrasound (microUS).ResultsAlbumin-shelled MBs can be labeled with 18F-SFB directly and conjugated with antibodies for dual molecular imaging. The albumin-shelled tMBs show a lifetime in 30 min in the blood pool and a highly specific adherence to tumor vessels in mice bearing human breast cancer.ConclusionsFrom the evaluations of whole-body biodistribution, the potential of the dual molecular imaging probe for drug or gene delivery in animal experiments with albumin shelled MBs has been investigated.

► Biodistribution of albumin-shelled, targeted microbubbles (tMBs) were first demonstrated.
► 18F-SFB-labeled VEGFR2 tMBs were synthesized.
► The characteristics of tMBs in tumor animal model were investigated with microPET and microUS.
► The tMBs show a lifetime in 30 minutes in the blood pool and a highly specific adherence to tumor vessels.
► The potential of the US/PET molecular imaging probe for drug or gene delivery with albumin shell has been investigated.