Quantum Dots Emitting in the Third Biological Window as Bimodal Contrast Agents for Cardiovascular Imaging

Physicians are demanding innovative technologies for multimodal imaging of the cardiovascular system that would lead to the appearance of advanced diagnosis and therapy procedures. This implies the simultaneous development of new imaging techniques and contrast agents whose synergy would make it possible. Optical coherence tomography (OCT) has recently emerged as a versatile and high-resolution clinical technique for cardiovascular imaging. Unfortunately, the lack of adequate contrast agents impedes the use of OCT for intracoronary multimodal imaging. In this work, the hitherto unexplored capability of semiconductor quantum dots (IR-QDs) emitting in the third infrared biological window (1.55-1.87 mu m) to act as multimodal agents for intracoronary imaging is demonstrated. Under single line laser excitation at 1.3 mu m, IR-QDs are capable of providing simultaneous backscattering contrast and efficient luminescence at 1.6 mu m. In this work, backscattered radiation is successfully employed to construct OCT images in both fluids and tissues whereas the infrared luminescence of the IR-QDs provides the possibility for simultaneous acquisition of high penetrating fluorescence images. The first multimodal (fluorescence + OCT) imaging of an artery using IR-QDs as contrast agents is provided herein demonstrating their outstanding potential for future clinical applications.