Singlet Oxygen Generation via Two-Photon Excited FRET

Abstract

A new approach to two-photon excited photodynamic therapy has been developed. A dendritic array of eight donor chromophores capable of two-photon absorption (TPA) was covalently attached to a central porphyrin acceptor. Steady-state fluorescence measurements demonstrated that the donor chromophores transfer excited-state energy to the porphyrin with 97% efficiency. Two-photon excitation of the donor chromophores at 780 nm resulted in a dramatic increase in porphyrin fluorescence relative to a porphyrin model compound. Enhanced singlet oxygen luminescence was observed from oxygen-saturated solutions of the target compound under two-photon excitation conditions.

Enhanced Two‐Photon Absorption of Organic Chromophores: Theoretical and Experimental Assessments

“…(48)(49)(50)(51)(52)(53)(54)(55) have to be truncated to some reasonable number of excited states, which is also the case of usual SOS applications. Modern computational codes use direct Krylov sub-space methods to calculate excited states.…”

“…Finally, out of 8 contributions (Eqs. (48)(49)(50)(51)(52)(53)(54)(55)) to the response, terms involving multi-dimensional tensors such as V αβγδ bear the majority of the computational expense. Identifying dominant contributions into the total response allows one to formulate truncated approaches to calculate NLO responses of large and complex molecular systems at different levels of accuracy.…”

“…This is particularly true for applications based on organic TPA chromophores thanks to the synthetic versatility and modularity offered by organic chemistry. This opens the way toward synthetically challenging strategies for the creation of highly robust smart materials and devices based on either all-organic nanoarchitectures [51,52,309] (in particular for bioimaging or biomedical applications by combination of two-photon absorbers with bioactive molecules such as drugs, proteins, recognition moieties, etc.) or hybrid materials [19,65,[310][311][312] such as metal/organic, semiconductor/metallic, nanoassemblies or functionalized surfaces.…”

Fluorescent Dyes Used in Polymer Carriers as Imaging Agents in Anticancer Therapy

“…These groups constitute an attractive trigger because UV light induced Wolff rearrangement of DNQ to a 3-indenecarboxylic acid group with hydrophilic properties enhancing water solubility of that compound. Moreover, infrared light can be applied in photodynamic therapy [217][218][219][220] and liposome degradation [221]. Furthermore, mechanopores along the polymer poly(methyl acrylate) backbone (e.g., cyclobutane mechanopores) can be activated in polymers containing a coumarin dimer probe by mechanochemical scisson under pulsed ultrasound conditions (sonochemical) in solid state [222].…”

Significant effects of branches and bromine substitution of near-infrared two-photon photosensitizers on the generation of singlet oxygen

“…Near-infrared photon has remarkable advantage, such as low energy, excellent penetration and negligible damage to normal biological tissues. Hence, the utilization of near-IR laser to irradiate two-photon triplet photosensitizers to generate singlet oxygen receives considerable attentions [12][13][14][15][16][17][18]. While unfortunately, near-infrared TPA photodynamic therapy has never reached its full potentials due to the absence of the criteria for the design of photosensitizers with large twophoton absorption cross sections and high singlet oxygen quantum yields.…”