Indocyanine green-loaded pulmonary surfactant-based nanoparticles for near-infrared fluorescent detection of lung metastasis via inhalation delivery

Abstract

Lung cancer is one of the deadliest types of cancers worldwide, possessing a high number of patients and death rate. The first and foremost treatment to such diagnosed lung cancers is surgical removal, where physical excisions of the lung cancer tissues are performed. In such basic surgical treatments, minimizing the accidental removal of the healthy lung tissue is critical, as it is the major factor in affecting the patient’s life quality post-surgery. Thus, an imaging system that can distinguish the tumor tissues from normal lung tissues with high accuracy and precision is in need of development. Currently, various near-infrared fluorescent materials are being used to distinguishing certain tissues in biological systems. In particular, Indocyanine Green, a fluorescent with its emission spectrum near 780nm, is an FDA-approved material with high biosafety. By loading such fluorescent material onto a nanoparticle based on pulmonary surfactant, a commercially available material naturally abundant within the lungs, clinical safety may be maximized. Inhalation delivery of these nanoparticles showed specific delivery to only the lungs, thereby decreasing possible toxicity in other major organs. Such delivered particles have been confirmed to be able to distinguish lung cancer nodules from healthy lung tissue with highly efficient negative imaging, mainly because of the physical barriers of the tumor nodules and the decreased ratio of macrophages in the nodules, which is the major type of cell that exhibit uptaking ability towards nanoparticles. Furthermore, the fact that such fluorescent nanoparticles distinguish tumor regions from healthy tissues more efficiently than other small-molecule fluorescent materials have been confirmed, yielding the potential to decrease the general dosage of the fluorescent material in use, possibly decreasing the toxicity while increasing the economic efficiency of the imaging system. In short, this study allows ICG to behave as a nanoparticle by loading it onto a liposome-form nanoparticle based on a bio-safe material, the pulmonary surfactant. Via inhalation of this newly synthesized Surf-ICG nanoparticles, an accurate and effective detection of the lung cancer nodules from the background-existing healthy lung tissues can be met.