Nontoxic Intralipid-DSPE-PEG2000-COOH Nanoparticles as Optical Coherence Tomography Contrast Agents for Tumor Angiography in Live Animals

Optical coherence tomography (OCT) is a noninvasive imaging technique that has been extensively used in the medical field for visualizing tissue microstructure. However, imaging microvasculature in tumors using an OCT is challenging due to slow blood flow, strong scattering, and attenuation of light by solid tumor tissue. To overcome these limitations, nontoxic intralipid-DSPE-PEG2000-COOH (IDPC) nanoparticles were synthesized as contrast agents for enhanced tumor angiography in live animals. The study aimed to investigate the potential of IDPC nanoparticles in improving OCT angiography of the OCTA (OCCT) for mice normal ears and superficial tumors in the near-infrared (NIR-II) window. Pure 20% intralipid exhibits limited water solubility and is rapidly absorbed by hemoglobin cells in the bloodstream, which makes it unsuitable for imaging and therapy purposes. However, newly synthesized IDPC nanoparticles can successfully overcome these limitations. During the study, IDPC nanoparticles were used to enhance angiography in mouse ears and tumors. The results showed that the use of IDPC nanoparticles increased vessel densities (AVD) by 22% in mice ears and 45% in tumors as well as signal intensity by 18% in ears and 16% in tumors. Moreover, IDPC nanoparticles demonstrated high cell viability (∼99%) and excellent biocompatibility in the blood biochemical analysis of mice. These findings suggest that the safe and nontoxic IDPC nanoparticles have clinical potential to enhance the scope of OCT imaging for investigating vascular diseases and tumors. The unique properties of IDPC nanoparticles can also be beneficial in exploring biological mechanisms, physiological complexities, and cellular and molecular behaviors in various diseases.