Photochemical internalization (PCI) is a drug and gene therapy delivery method originally developed to improve the release of

macromolecule A macromolecule is a very large molecule important to biophysical processes, such as a protein or nucleic acid. It is composed of thousands of covalently bonded atoms. Many macromolecules are polymers of smaller molecules called monomers. The ...

s and

hydrophilic A hydrophile is a molecule or other molecular entity that is attracted to water molecules and tends to be dissolved by water.Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon'' Oxford: Clarendon Press. In contrast, hydrophobes are no ...

chemotherapeutic Chemotherapy (often abbreviated to chemo and sometimes CTX or CTx) is a type of cancer treatment that uses one or more anti-cancer drugs (chemotherapeutic agents or alkylating agents) as part of a standardized chemotherapy regimen. Chemotherap ...

agents from endosomes and

lysosome A lysosome () is a membrane-bound organelle found in many animal cells. They are spherical vesicles that contain hydrolytic enzymes that can break down many kinds of biomolecules. A lysosome has a specific composition, of both its membrane prot ...

s to the cytosol of targeted cancer cells. PCI is based on the use of endosomal and lysosomal localizing amphiphilic photosensitizers which, after activation by

light Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 tera ...

, induce photochemical reactions resulting in destruction of

endocytic Endocytosis is a cellular process in which substances are brought into the cell. The material to be internalized is surrounded by an area of cell membrane, which then buds off inside the cell to form a vesicle containing the ingested material. E ...

membranes mediated by reactive oxygen species (ROS). The photochemical destabilization of the membrane of the endocytic vesicle result in an endosomal escape of the entrapped drugs.Selbo PK, Weyergang A, Høgset A, Norum OJ, Berstad MB, Vikdal M, Berg K (2010) Photochemical internalization provides time- and space-controlled endolysosomal escape of therapeutic molecules. J Control Release, 148 (1): 2-12
doi:10.1016/j.jconrel.2010.06.008
/ref> The technology was invented by Kristian Berg at the

Norwegian Radium Hospital Oslo University Hospital, Radiumhospitalet ( no, Oslo universitetssykehus, Radiumhospitalet) is one of the four campuses of Oslo University Hospital in Oslo, Norway, and is dedicated to cancer treatment. This part of the hospital is the most specia ...

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