text: Ligand-targeted liposomes are used for a variety of applications depending on the liposome, ligand, and liposome contents. Ligand-targeted liposomes can also be used for diagnostics through imaging. The liposomes can contain imaging agents to aid in visualization such as fluorescent dyes, labeling probes, and contrast agents. Commonly, a radioactive gamma-emitter, fluorescent marker, or magnetic resonance imaging (MRI) agent is encapsulated in the liposome for this application. The active targeting mechanism of LTLs allows the target tissue to retain the imaging agent while the remaining agent is cleared from circulation. The ligand-targeted liposomes increase the specificity and sensitivity of the images taken through positron emission tomography (PET), single-photon emission computed tomography (SPECT), and MRI techniques through the ligand localization to receptors of interest. Biotinylated liposomes containing [Ga] coupled with a later injection of avidin have been shown to reduce background signal and produce the needed contrast for imaging while reducing the circulation time of radioactive imaging agent. Molecular imaging of processes over time in vivo is also made possible using ligand-targeted nanoparticles. As of 2015,  many ligand-targeted imaging agents such as MIP-1404, MIP-1405, MIP-1072, MIP-109, and F-DCFBC were undergoing clinical trials. The ability of a liposome to encapsulate these imaging agents and deliver them to specific regions through ligand targeting is helpful for precision detection.
  Ligand-targeted liposomes are a promising method of drug delivery. These systems are efficient in delivering the drug to localized areas with low peripheral distribution, which minimizes the off-target effects. The favorable biodistribution to target tissue is an encouraging property of this drug delivery system. In addition to highly targeting tissue, the ligand-targeted liposomes have a short circulating half-life, so they can be quickly cleared from the bloodstream. Ligand-targeted liposomes can be used to deliver AuNRs for localized delivery of photo-thermal therapy in cancer treatment. Photodynamic therapy (PDT) is a non-invasive cancer therapy that relies on a photosensitizing (PS) pro-drug to interact with light and oxygen as a cancer therapeutic agent. PSs can be encapsulated in LTLs, allowing them to move through systemic circulation to the tumor site for ligand binding to specify the area of their effect. Using PDT causes damage to cancer cells and tumor microvasculature. There are many liposome-based products currently approved or undergoing clinical trials.
  Aside from cancer therapies, ligand-targeted liposomes can also be used to target inflammation in the body that may be present due to rheumatoid arthritis, psoriasis, vascular inflammation, and organ transplantation. E-selectin is a cell-specific receptor expressed by inflamed endothelium that ligands can target.
  LTLs also have the potential for localized treatment in fungal infections. AmBisome (L-AMB) is an LTL that contains Amphotericin B (AMPH-B), an anti-fungal treatment that is effective for a broad variety of fungal infections. AMPH-B can be toxic after prolonged exposure, making it a good candidate for the targeting and rapid clearing of systemic circulation of LTLs. AmBisome is also effective due to the inflammation in the area of fungal activity, which increases vascular permeation.