Photolytical reactions for light induced biological effectors release: on the road to the phototherapeutic window

Abstract

The use of caged compounds, defined as photolabile precursors of biological effectors, have proven to be attractive in various fields of biology. Photolytical reactions have been widely used to allow a rapid and efficient concentration jump of various biological effectors within organized biological systems. During the last two decades, the challenge was to overcome the difficulty that only high energy UV light was used to induce photochemical reactions on photoremovable protecting groups (PPGs). Infrared-sensitive PPGs should be able to improve in vivo applications of caged compounds. The present review is focused on recent strategies enabling the use of excitation wavelength inside the photo-therapeutical window (600-1000 nm) to efficiently and specifically cleave a chemical bond.

Photoactivatable Liposomes for Blue to Deep Red Light-Activated Surface Drug Release: Application to Controlled Delivery of the Antitumoral Drug Melphalan

“…In particular, blue light-sensitive PPGs have been reported in the coumarin, − o -nitrobenzyl , and o -nitrophenethyl series. To be able to use a red-light activation, the use of upconversion (UC) assisted photolysis has been recently explored to trigger drug delivery upon photolysis from nanocarriers in vivo. , UC is an anti-Stokes process able to convert photons into higher-energy, allowing for example, the conversion of red to blue light. UC systems based on triplet–triplet annihilation upconversion (TTA-UC) of organic chromophores have very recently been applied for life science applications. − In TTA-UC, photon energies absorbed by (at least) two donor chromophoresalso called “sensitizers”are transferred to emitter chromophoresalso called “annihilators”through collisions resulting in triplet–triplet energy transfer.…”

Ultrafast and efficient energy transfer in a one- and two-photon sensitized rhodamine-BODIPY dyad: a perspective for broadly absorbing photocages

“…5,6 Such applications favor excitation light of the so called ''phototherapeutic window'' (600-1000 nm) which provides less phototoxicity and deep tissue penetration due to little light scattering and competitive absorption. 7 Photolabile Protecting Groups (PPGs) that operate in this area are rare and mainly include BODIPY-, xanthene-or cyanine-derived structures. 8,9 However, while demonstrating strong absorption, these compounds often lack efficient photorelease quantum yields.…”

Two-Photon Sensitive Coumarinyl Photoremovable Protecting Groups with Rigid Electron-Rich Cycles Obtained by Domino Reactions Initiated by a 5-exo-Dig Cyclocarbopalladation

“…[23][24][25][26][27] In most cases, those modification lead to coumarinyl PPG with only modest uncaging quantum yields. 2,28 In particular, Zhu and coworkers 25 introduced 7-diethylaminocoumarin (DEAC) analogues with electron-rich styryl appendages at the 3-position (1).…”

“…Coumarinylmethyl PPGs are widely used phototriggers due to the rapid photolytic reaction (in the nanosecond range). , These latter caging groups have already been modified by π-extended electron-donating or electron-withdrawing moieties, leading to blue and green light-activatable PPGs. − In most cases, those modifications lead to coumarinyl PPGs with only modest uncaging quantum yields. , In particular, Zhu and co-workers introduced 7-diethylaminocoumarin (DEAC) analogues with electron-rich styryl appendages at position 3 ( 1 ).…”