Liposomes and their applications in molecular imaging.

Molecular imaging is a relatively new discipline with a crucial role in diagnosis and treatment tracing of diseases through characterization and quantification of biological processes at cellular and sub-cellular levels of living organisms. These molecular targeted systems can be conjugated with contrast agents or radioligands to obtain specific molecular probes for the purpose of diagnosis of diseases more accurately by different imaging modalities. Nowadays, an interesting new approach to molecular imaging is the use of stealth nanosized drug delivery systems such as liposomes having convenient properties such as biodegradability, biocompatibility and non-toxicity and they can specifically be targeted to desired disease tissues by combining with specific targeting ligands and probes. The targeted liposomes as molecular probes in molecular imaging have been evaluated in this review. Therefore, the essential point is detection of molecular target of the disease which is different from normal conditions such as increase or decrease of a receptor, transporter, hormone, enzyme etc, or formation of a novel target. Transport of the diagnostic probe specifically to targeted cellular, sub-cellular or even to molecular entities can be performed by molecular imaging probes. This may lead to produce personalized medicine for imaging and/or therapy of diseases at earlier stages.