A Luminescent, Water-Soluble Ir(III) Complex as a Potential Photosensitizer for Two-Photon Photodynamic Therapy

Elisabeta I Szerb,Giovanna Palermo,Lucie Sancey,Sharmistha Chatterjee,Massimo La Deda,Loredana Ricciardi,Giuseppe Strangi

doi:10.3390/app112411596

Abstract

This work reports the study of two-photon induced properties of a highly luminescent cyclometalated Ir(III) complex, [Ir(ppy)2(en)] OOCCH3 (1), ppy = 2-phenylpyridine, en = ethylenediamine. Steady-state and time-resolved fluorescence measurements were performed by exciting 1 at the biologically relevant wavelength of 800 nm, whereas, the generation of singlet oxygen (1O2) was evaluated using 9,10-Anthracenediyl-bis(methylene)dimalonic acid (ABDA) as a detection probe. Preliminary in vitro experiments with U87-MG cells were performed, showing the potential of this compound as a two-photon photodynamic therapy (2P-PDT) agent at NIR wavelengths.

Highlights

Photodynamic therapy (PDT) is a minimally invasive clinical approach approved for the treatment of numerous cancers [1] and non-cancerous diseases, which include psoriasis [2,3], age-related macular degeneration [4], viral [5,6] and fungal [7] infections
To overcome this drawback more attention has recently focused on “deep PDT techniques” [10]—such as two-photon photodynamic therapy (2P-PDT)—which involves the use of two-photon absorbing PSs that are triggered by excitation wavelengths in the spectral NIR region [11,12]
Using a femtosecond Ti/sapphire laser as excitation source, we obtained the emission spectrum and lifetime of [Ir(ppy)2] OOCCH3 (1) in aqueous solution resulting from two-photon excitation

Summary

Introduction

Photodynamic therapy (PDT) is a minimally invasive clinical approach approved for the treatment of numerous cancers [1] and non-cancerous diseases, which include psoriasis [2,3], age-related macular degeneration [4], viral [5,6] and fungal [7] infections. It requires the simultaneous presence of three key components: a photosensitizer (PS), a light source and molecular oxygen. To overcome this drawback more attention has recently focused on “deep PDT techniques” [10]—such as two-photon photodynamic therapy (2P-PDT)—which involves the use of two-photon absorbing PSs that are triggered by excitation wavelengths in the spectral NIR region [11,12].

Methods

Results

Conclusion