Dual-Mode Contrast Agents with RGD-Modified Polymer for Tumour-Targeted US/NIRF Imaging

Background: Cancer diagnosis and treatment during the early stages of disease remain extremely challenging clinical tasks. The development of effective multimode contrast agents could greatly facilitate the early detection of cancer. Materials and Methods: We prepared dual-mode contrast agents using a biotin/avidin bioamplification system. Through in vivo and in vitro experiments, we verified the imaging performance of this contrast agents in both fluorescence and ultrasound and its targeting specificity for MDA-MB-231 cells. Results: The RGD peptide-labelled microbubbles showed excellent targeting of alpha v beta 3 integrin expressed by MDA-MB-231 cells in vitro and in vivo. The signal intensity and time duration of ultrasound imaging using these particles were superior to those obtained with a typical ultrasound contrast agent in the clinic. The tumour areas also demonstrated high Cy5.5 accumulation by fluorescence imaging. Conclusion: The results show that this targeted dual-mode imaging system yields outstanding US/NIRF imaging results, possibly allowing the early clinical diagnosis of cancer.