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

Abstract

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 µm) to act as multimodal agents for intracoronary imaging is demonstrated. Under single line laser excitation at 1.3 µm, IR-QDs are capable of providing simultaneous backscattering contrast and efficient luminescence at 1.6 µm. 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.

Optical Nanoparticles for Cardiovascular Imaging

“…A future work will be incubation of the functionalized GNSs with endothelial cells or macrophages (since they are two cellular types related to the process of atherosclerosis) under flow conditions, and achieving an OCT contrast enhancement provided by this incubation process . Moreover, due to the fast growth of catheter‐based fluorescence imaging used in atherosclerosis, we used PbS QDs which can be excited by the IV‐OCT catheter and provide an emission around 1500 nm to image the aorta . As shown in Figure , the PbS QDs were injected into one artery that contained the IV‐OCT catheter inside.…”

“…The instantaneous (real time) and accumulative infrared fluorescence images generated by the PbS QDs inside the artery are also shown for the different positions of the IV‐OCT catheter and named A, B, C, D, and E. The corresponding OCT cross‐sectional images are also displayed together with the transverse OCT image of the artery. Reproduced with permission . Copyright 2017, Wiley‐VCH.…”

Designating Vulnerability of Atherosclerotic Plaques

“…Therefore, they possess great potential in the fields of biological imaging, molecular markers [47][48][49], and drug delivery [50][51][52]. QDs are useful in tumor detection [53], cardiovascular imaging [54], and cancer targeting [55]. Their high optical absorption and biocompatibility made noble metal nanoparticles to be widely used as biomarkers [56,57].…”

“…On the other hand, graphene quantum dots (GQDs) are extensively used in biomedical applications [58,59] since they exhibit lower cytotoxicity than cadmium (Cd), selenium (Se)-, and lead (Pb)-based quantum dots do [60]. The use of QDs as contrast agents in magnetic resonance imaging (MRI) [61], optical coherence tomography (OCT) [54], positron emission tomography (PET), single-photon emission computed tomography (SPECT), optical imaging such as fluorescence spectroscopy and Raman spectroscopy, and photoacoustic imaging (PAI) [62][63][64] proved their potential as diagnostic agents.…”

Magnetic Nanoplatelets for High Contrast Cardiovascular Imaging by Magnetically Modulated Optical Coherence Tomography

“…In order to further improve the imaging capability of IC‐OCT, especially for arteriosclerosis, and to develop it into a molecular imaging technique, research into contrast agents working at these wavelengths has begun and the combination with fluorescence imaging techniques was already demonstrated . So far, this has been more laborious because of the scarcity of optical materials and chromophores suitable for these conditions.…”