Ln(III) Complexes Embedded in Biocompatible PLGA Nanoparticles as Potential Vis-to-NIR Optical Probes

Abstract

In this contribution, we present the spectroscopic study of two NIR emitting hydrophobic heteroleptic (R,R)-YbL1(tta) and (R,R)-NdL1(tta) complexes (with tta = 2-thenoyltrifluoroacetonate and L1 = N,N′-bis(2-(8-hydroxyquinolinate)methylidene)-1,2-(R,R or S,S)-cyclohexanediamine), both in methanol solution and embedded in water dispersible and biocompatible poly lactic-co-glycolic acid (PLGA) nanoparticles. Thanks to their absorption properties in a wide range of wavelengths extending from the UV up to the blue and green visible regions, the emission of these complexes can be effectively sensitized using visible radiation, which is much less harmful to tissues and skin than the UV one. The encapsulation of the two Ln(III)-based complexes in PLGA allows us to preserve their nature, making them stable in water and to test their cytotoxicity on two different cell lines, with the aim of using them in the future as potential bioimaging optical probes.

Circularly polarized luminescence activity in the near infrared spectral region of a water-soluble ytterbium(iii) complex containing a conjugated chromophoric ligand

“…Recently, some of us demonstrated that the Yb(III) luminescence can be efficiently sensitized upon excitation of a conjugated ligand system in different spectral regions: from UV to Vis. 19,20 In order to efficiently sensitize the Ln(III) luminescence at NIR wavelengths, one possible strategy is the design of ligands including a two-photon absorbing chromophoric antenna capable of transferring the excitation energy to the Ln(III) ion. Two-photon (2P) excitation is a nonlinear optical phenomenon which takes place when an excited state of a chromophore can be populated by the concomitant absorption of two photons, whose wavelength is twice that of a Luminescent Materials Laboratory, DB, Universita `di Verona, and INSTM, UdR Verona, Strada Le Grazie 15, 37134 Verona, Italy.…”