Synthesis and Development of Lipoprotein-Based Nanocarriers for Light-Activated Theranostics

One of the central directions of research in medical theranostics is the design of agents that can simultaneously exert a therapeutic effect and enable molecular imaging. Although several types of small molecules (e.g., radiotracers and photosensitizers (PS)) have been successfully used for disease-related theranostics, nanocarriers have a variety of advantages over small molecules, such as enhanced pharmacokinetic profiles and drug-shielding ability. In addition, nanocarriers are versatile and can be loaded with multiple agents in multiple ways (e.g., surface loading, core loading), which allows the packaging of several imaging and therapeutic molecules and thus offers the potential for image-guided therapy. At the theranostics frontier, the loading of phototoxic agents into nanocarriers enables spatial and temporal control of therapeutic drug activation or release, with the goal of treatment of disease in a selective and specific manner, thus improving the therapeutic index. Along with light-activated therapy, imaging modalities such as fluorescence imaging, radiography, magnetic resonance imaging (MRI) and computed tomography (CT) facilitate the understanding of drug distribution and can provide valuable information towards the treatment outcome. As natural and endogenous nanocarriers, lipoproteins have long been utilized in nanomedicine as delivery tools for therapeutics and imaging contrast agents. They have several advantages for light-activated theranostics, such as excellent size control, high payload-carrying capacity, biocompatibility, biodegradability and nonimmunogenicity. 1.1. Photosensitizers