Recently, it has been suggested that quantum dots (QDs) could be used in the photodynamic therapy of cancer as resonance energy donors for conventional porphyrin type photosensitizers. Here we present the results of the spectroscopic studies on the formation of a non-covalent complex between QDs and photosensitizer chlorin Ce₆ in an aqueous medium and in the presence of bovine serum albumin (BSA). Changes in the absorption and fluorescence spectra of QDs and Ce₆ revealed the formation of a QD-Ce₆ complex which occurs due to hydrophobic interaction between the nonpolar moiety of an amphiphilic photosensitizer and the hydrophobic part of the lipid-based coating of the QD. The photosensitizer conjugated with the QD could be indirectly excited by the Forster resonance energy transfer (FRET) from the QD to Ce₆. The investigation on the capacity of such complex to generate ¹O₂ showed that the QD-Ce₆ complex irradiated by visible light is able to produce ¹O₂ more efficiently than QDs or Ce₆ taken separately. The photoinactivation of cells incubated with the QD-Ce₆ complex and irradiated in the spectral region where the photosensitizer does not absorb provided evidence that such complex could induce FRET-mediated cell destruction.

Keywords: quantum dots, lipids, photosensitizer, energy transfer, photodynamic therapy
PACS: 87.64.kv, 87.85Rs

MODIFIKUOTO PAVIRŠIAUS KVANTINIŲ TAŠKŲ IR CHLORINO e₆
KOMPLEKSAI FOTODINAMINEI TERAPIJAI
R. Rotomskis^a,b, J. Valančiūnaitė^b, A. Skripka ^b, S. Steponkienė^b, G. Špogis^b, S. Bagdonas ^a, G. Streckytė^a
aVilniaus universiteto Lazerinių tyrimų centras, Vilnius, Lietuva
^bVilniaus universiteto Onkologijos institutas, Vilnius, Lietuva

Pastaraisiais metais buvo pasiūlyta, kad kvantiniai taškai (KT) galėtų tapti energijos donorais tradiciniams porfirinams, taikomiems vėžio gydymui fotodinaminės terapijos metodu. Šiame darbe spektroskopiniais metodais tirtas nekovalentinės prigimties komplekso tarp KT ir fotosensibilizatoriaus chlorino e₆ (Ce₆) susidarymas vandeninėje terpėje ir jaučio serumo albumino aplinkoje. KT ir Ce₆ sugerties ir fluorescencijos spektrų pokyčiai atskleidė, kad KT ir Ce₆ komplekso formavimasis vyksta dėl hidrofobinės sąveikos tarp amfifilinio fotosensibilizatoriaus molekulės nepolinės dalies ir hidrofobinės KT lipidinio dangalo dalies. Tokiuose kompleksuose fotosensibilizatorius gali būti sužadinamas netiesiogiai vykstant Fiorsterio rezonansinės energijos pernašai. Švitinamas regimosios šviesos spinduliuote, KT ir Ce₆ kompleksas generuoja singuletinį deguonį aktyviau negu jo atskirai švitinami komponentai. Inkubavus vėžio ląsteles KT ir Ce₆ komplekso tirpalu ir pašvitinus šviesa, kurios sensibilizatorius nesugeria, didelė dalis ląstelių žuvo. Stabilių KT ir fotosensibilizatorių kompleksų citotoksiškumas ląstelėse galėtų būti panaudotas kuriant selektyvias fotodinaminės terapijos metodikas.

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