Nanoparticles as vehicles for delivery of photodynamic therapy agents

Photodynamic therapy (PDT) in cancer treatment involves the uptake of a photosensitizer by cancer tissue followed by photoirradiation. The use of nanoparticles as carriers of photosensitizers is a very promising approach because these nanomaterials can satisfy all the requirements for an ideal PDT agent. This review describes and compares the different individual types of nanoparticles that are currently in use for PDT applications. Recent advances in the use of nanoparticles, including inorganic oxide-, metallic-, ceramic-, and biodegradable polymer-based nanomaterials as carriers of photosensitizing agents, are highlighted. We describe the nanoparticles in terms of stability, photocytotoxic efficiency, biodistribution and therapeutic efficiency. Finally, we summarize exciting new results concerning the improvement of the photophysical properties of nanoparticles by means of biphotonic absorption and upconversion. Photodynamic therapy (PDT) in cancer treatment involves the uptake of a photosensitizer by cancer tissue followed by photoirradiation. The use of nanoparticles as carriers of photosensitizers is a very promising approach because these nanomaterials can satisfy all the requirements for an ideal PDT agent. This review describes and compares the different individual types of nanoparticles that are currently in use for PDT applications. Recent advances in the use of nanoparticles, including inorganic oxide-, metallic-, ceramic-, and biodegradable polymer-based nanomaterials as carriers of photosensitizing agents, are highlighted. We describe the nanoparticles in terms of stability, photocytotoxic efficiency, biodistribution and therapeutic efficiency. Finally, we summarize exciting new results concerning the improvement of the photophysical properties of nanoparticles by means of biphotonic absorption and upconversion. the absorption coefficient divided by the number of molecular entities contained in a volume of the absorption medium along the light path. In the case of biphotonic excitation, it is a two photon absorption (TPA) cross-section. the quality of not having toxic or injurious effects on biological systems. How nanomaterials interact with the human body and, eventually, how those interactions determine the clinical success of a medical device. organic nanoparticles made of polymer that can be degraded in a biological environment. This occurs mainly by hydrolysis or enzymatic reactions. inorganic nanoparticles with porous characteristics made mainly of silica, titania or alumina. diffusion MRI enables the study of water diffusion in a variety of environments (e.g. biological tissues). Diffusion MRI can be performed at various time points after treatment to monitor changes in tumour diffusion and tumour growth. After PDT, for instance, brain cells die, trapping water molecules inside them (cellular pumps are no longer functioning). nanoparticles (usually silica) doped with a large number of dye molecules (either organic or inorganic). There can be tens of thousands of dye molecules inside a single silica particle. amount of photosensitizer in nanoparticles divided by the amount of nanoparticles, usually expressed as a percentage. drug loading divided by the theoretical drug loading (expressed as a percentage). a type of treatment in which body tissue is exposed to high temperatures to damage cancer cells or to make them more sensitive to the effects of radiation and certain anticancer drugs. nanoparticles made of metal, such as gold or silver. nanoparticles with different units (e.g. targeting units, imaging agents) or nanoparticles that have several functions (therapy, diagnosis). the term nanoparticle is generally used to refer to a small particle with all three dimensions measuring less than 1000 nanometres. effect on cell survival dependent upon the incident level of light (toxic effect on cells induced by absorption of light). the process by which a photochemical or photophysical alteration occurs in one molecular entity as a result of initial absorption of radiation by another molecular entity called a photosensitizer. light-sensitive molecule that can activate an alteration in another molecular entity. Photodynamic therapy is based on the formation of singlet oxygen from triplet oxygen by a photosensitizer. Singlet oxygen gives rise to peroxidative reactions that can cause cell damage and death. PDT-induced thrombosis. Photothrombic efficacy is visually assessed for each CAM according to the vessel closure efficacy. The number of defined events that occur per photon absorbed by the system. nanoparticles that can be stimulated by X-rays or other radiation sources and will generate light excitation resulting from successive or simultaneous absorption of two photons by an atom or a molecular entity. The simultaneous two-photon absorption can also be called biphotonic excitation. a nonlinear optical effect in which light frequency is increased.