Radiolabeled Liposomes for Nuclear Imaging Probes

Abstract

Quantitative nuclear imaging techniques are in high demand for various disease diagnostics and cancer theranostics. The non-invasive imaging modality requires radiotracing through the radioactive decay emission of the radionuclide. Current preclinical and clinical radiotracers, so-called nuclear imaging probes, are radioisotope-labeled small molecules. Liposomal radiotracers have been rapidly developing as novel nuclear imaging probes. The physicochemical properties and structural characteristics of liposomes have been elucidated to address their long circulation and stability as radiopharmaceuticals. Various radiolabeling methods for synthesizing radionuclides onto liposomes and synthesis strategies have been summarized to render them biocompatible and enable specific targeting. Through a variety of radionuclide labeling methods, radiolabeled liposomes for use as nuclear imaging probes can be obtained for in vivo biodistribution and specific targeting studies. The advantages of radiolabeled liposomes including their use as potential clinical nuclear imaging probes have been highlighted. This review is a comprehensive overview of all recently published liposomal SPECT and PET imaging probes.

Hydroxyapatite Nanocrystals Integrated into Mesoporous Silica for Sustained Delivery of Doxorubicin

“…Through the incorporation of a radioactive isotope into the material of interest, radiolabeling enables researchers to monitor its movement, localization, and clearance dynamics in real time, providing valuable insights into its pharmacokinetics and tissue-specific accumulation. By utilizing imaging modalities, such as positron emission tomography (PET), single-photon emission computed tomography (SPECT), or autoradiography, radiolabeled materials can be visualized noninvasively, allowing for the precise localization and quantification of their distribution within specific organs or tissues, or even at the cellular level. − Moreover, radiolabeling facilitates the determination of key pharmacokinetic parameters, including blood circulation half-life, tissue residence time, and metabolic stability, providing comprehensive data crucial for optimizing the design and formulation of novel therapeutic agents. This information aids in the development of targeted drug delivery systems, ensuring effective delivery to the desired sites while minimizing systemic exposure and potential toxicity. − …”

Polymeric Nanoparticles for Drug Delivery

“…982 Researchers combine these radionuclides with biologically relevant molecules to develop radiopharmaceuticals, which are then applied to visualize organs or identify infected tissues. 983 Depending on the specific decay processes of radionuclides, two primary nuclear imaging modalities have been developed: single-photon emission computed tomography (SPECT) and positron emission tomography (PET). SPECT is designed for gamma-emitting radionuclides, while PET is specifically used for positron-emitting radionuclides.…”

“…Radionuclides are unstable isotopes that emit radiation primarily through radioactive decay, including alpha (α) particles, charged beta particles (positrons, β+; electrons, β−), gamma (γ) rays, or electron (e) radiation . Researchers combine these radionuclides with biologically relevant molecules to develop radiopharmaceuticals, which are then applied to visualize organs or identify infected tissues . Depending on the specific decay processes of radionuclides, two primary nuclear imaging modalities have been developed: single-photon emission computed tomography (SPECT) and positron emission tomography (PET).…”

Application of Nanoparticles in the Diagnosis of Gastrointestinal Diseases: A Complete Future Perspective

“…Liposomal radiotracers have emerged as promising nuclear imaging probes, and various methods for radionuclide labeling (such as encapsulation within liposomes to protect them from enzymatic degradation or protein binding) and synthetic strategies, have been extensively investigated to enhance their biocompatibility, stability, and specific targeting capabilities. 281 For example, Lee et al have introduced a novel PET imaging strategy that capitalizes on the differential esterase activity of tumors and mononuclear phagocyte system organs. They utilize 124 I-labeled liposomes as radiotracers, which are rapidly eliminated from the liver and spleen upon cleavage by esterases.…”