Multi-photon excitation in uncaging the small molecule bioregulator nitric oxide

Abstract

Multi-photon excitation allows one to use tissue transmitting near-infrared (NIR) light to access excited states with energies corresponding to single-photon excitation in the visible or ultraviolet wavelength ranges. Here, we present an overview of the application of both simultaneous and sequential multi-photon excitation in studies directed towards the photochemical delivery (‘uncaging’) of bioactive small molecules such as nitric oxide (NO) to physiological targets. Particular focus will be directed towards the use of dyes with high two-photon absorption cross sections and lanthanide ion-doped upconverting nanoparticles as sensitizers to facilitate the uncaging of NO using NIR excitation.

Effects of light-activated diazido-PtIVcomplexes on cancer cellsin vitro

“…into the red region) through synthesis of new complexes alone. Alternatively, it might be worthwhile to tether such light-activatable complexes to up-converting nanoparticles that specifically home in on tumour cells [43,44]. Such nanoparticles could then up-convert near-infrared radiation, directed at the tumour with fibre optic devices, to emit visible light of the proper wavelength and sufficient intensity to achieve efficient photoactivation deeper within tumours.…”

Combination of nitric oxide and drug delivery systems: tools for overcoming drug resistance in chemotherapy

“…mPEG-PLGA-BNN6-DOX system presents a conceptual strategy to prevent the premature release of NO and encourage the targeted delivery of NO and drug. However, further efforts exploiting other NO donors or development of advanced remote activation strategies for deep tissue penetration such as two-photon excitation laser [71] or upconversion nanoparticles [72] are needed and warrant exploration.…”

Photo-Controlled Release of NO and CO with Inorganic and Organometallic Complexes

“…Preparation UCNPs with a mesoporous silica shell impregnated with Roussin's Black Salt (red dots), a photo active nitric oxide generator, and coated with poly(allylamine). NIR irradiation leads to upconversion to wavelengths overlapping the RBS absorbance and NO uncaging [53]. ( Needs Permission) Question: has this been obtained?…”

“…The result is a sensitized photoreaction of the photoNORM that depends on the presence of excited states with appropriate energies and desired reactivities but does not depend on Another approach to longer wavelength excitation is multiphoton excitation, which involves the combining the energy of more than one NIR photon to achieve the energies necessary to effect the desired photochemistry from a suitable precursor [53]. A second potential advantage of this approach is that, since the probability of two-photon excitation (TPE) is proportional to the square of the incident light intensity (I 2 ), it is most likely to occur at the focal point of the excitation beam.…”