title: Organically modified silica nanoparticles co-encapsulating photosensitizing drug and aggregation-enhanced two-photon absorbing fluorescent dye aggregates for two-photon photodynamic therapy.
abstract: We report energy-transferring organically modified silica nanoparticles for two-photon photodynamic therapy. These nanoparticles co-encapsulate two-photon fluorescent dye nanoaggregates as an energy up-converting donor and a photosensitizing PDT drug as an acceptor. They combine two features: (i) aggregation-enhanced two-photon absorption and emission properties of a novel two-photon dye and (ii) nanoscopic fluorescence resonance energy transfer between this nanoaggregate and a photosensitizer, 2-devinyl-2-(1-hexyloxyethyl)pyropheophorbide. Stable aqueous dispersions of the co-encapsulating nanoparticles (diameter < or = 30 nm) have been prepared in the nonpolar interior of micelles by coprecipitating an organically modified silica sol with the photosensitizer and an excess amount of the two-photon dye which forms fluorescent aggregates by phase separation from the particle matrix. Using a multidisciplinary nanophotonic approach, we show: (i) indirect excitation of the photosensitizer through efficient two-photon excited intraparticle energy transfer from the dye aggregates in the intracellular environment of tumor cells and (ii) generation of singlet oxygen and in vitro cytotoxic effect in tumor cells by photosensitization under two-photon irradiation.
authors.affiliation: Institute for Lasers, Photonics and Biophotonics, Department of Chemistry, State University of New York, Buffalo, NY 14260-3000, USA.
authors.forename: Sehoon
authors.initials: S
authors.lastname: Kim
authors.forename: Tymish Y
authors.initials: TY
authors.lastname: Ohulchanskyy
authors.forename: Haridas E
authors.initials: HE
authors.lastname: Pudavar
authors.forename: Ravindra K
authors.initials: RK
authors.lastname: Pandey
authors.forename: Paras N
authors.initials: PN
authors.lastname: Prasad
mesh_terms: D000042:Absorption; D000970:Antineoplastic Agents / Q000737:chemistry* / Q000494:pharmacology; D011232:Chemical Precipitation; D002734:Chlorophyll / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology; D005456:Fluorescent Dyes / Q000737:chemistry*; D006367:HeLa Cells / Q000187:drug effects / Q000473:pathology; D006801:Humans; D042541:Intracellular Space / Q000473:pathology; D008823:Micelles; D053758:Nanoparticles / Q000737:chemistry*; D010778:Photochemotherapy; D017785:Photons; D017319:Photosensitizing Agents / Q000737:chemistry* / Q000494:pharmacology; D026082:Singlet Oxygen / Q000737:chemistry; D013050:Spectrometry, Fluorescence
chemical_list: D000970:Antineoplastic Agents; D005456:Fluorescent Dyes; D008823:Micelles; D017319:Photosensitizing Agents; D002734:Chlorophyll; C083998:2-(1-hexyloxyethyl)-2-devinyl pyropheophorbide-a; D026082:Singlet Oxygen