ABSTRACT
Since liposomes, almost independently of their composition, size, and charge are almost quantitatively captured by cells of the reticuloendothelial system within the first hour after their intravenous administration, the main goals for liposome surface modification were to increase liposome longevity and stability in the circulation, to change liposome biodistribution, to achieve targeting effect, and to impart to liposomes some “unusual” properties. Liposome modification with antibodies and specific ligands leads to drastic changes in liposome biodistribution without necessary changes in the liposome surface properties: all the targeting phenomena take place because of specific recognition between liposome-immobilized substances and the appropriate target within the body. Liposome surface modification with chelating compounds or moieties capable of firm binding heavy metals with liposomes, serves a special application of liposome as diagnostic agents and will be discussed here in some detail later. The very simple quantitative criteria can be introduced to describe the interaction of the polymer-protected liposome with a macromolecule from an external solution.
