Abstract:Two photons are better than one: a square-planar Pt(II) complex with derivatized pyridine ligands was synthesized, which undergoes two-photon-induced ligand substitution with 600-740 nm light. Linear and quadratic density functional response theory allowed identification of the electronic transitions involved.
“…The introduction of extended conjugation into the amine ligands of square–planar Pt(II) complexes has allowed two-photon activation of ligand exchange using red and near-infrared (NIR) light. Interestingly, the optimum wavelength for two-photon activation of cis -[ PtCl 2 (MOPEP) 2 ], where MOPEP is the π -conjugated ligand 4-[2-(4-methoxyphenyl)ethynyl]pyridine, is shorter than twice the single-photon absorption wavelength [16]. Figure 3.Two-photon absorption (TPA) in the singlet metal-to-ligand charge-transfer ( 1 MLCT) band and subsequent excited-state absorption (ESA) allow highly conjugated ruthenium(II) systems, such as that shown, to be used for their optical power-limiting properties.…”
Section: Light Deliverymentioning
confidence: 99%
“…red light) that penetrate more deeply into tissues. For example, ligand substitution in square–planar Pt II complexes containing conjugated amine ligands can be activated by two-photon absorption, but interestingly, the absorption maximum for one-photon absorption is displaced slightly from the two-photon wavelength [16]. …”
Section: Photo-induced Release Of Bioactive Moleculesmentioning
This short review highlights some of the exciting new experimental and theoretical developments in the field of photoactivatable metal complexes and their applications in biotechnology and medicine. The examples chosen are based on some of the presentations at the Royal Society Discussion Meeting in June 2012, many of which are featured in more detail in other articles in this issue. This is a young field. Even the photochemistry of well-known systems such as metal–carbonyl complexes is still being elucidated. Striking are the recent developments in theory and computation (e.g. time-dependent density functional theory) and in ultrafast-pulsed radiation techniques which allow photochemical reactions to be followed and their mechanisms to be revealed on picosecond/nanosecond time scales. Not only do some metal complexes (e.g. those of Ru and Ir) possess favourable emission properties which allow functional imaging of cells and tissues (e.g. DNA interactions), but metal complexes can also provide spatially controlled photorelease of bioactive small molecules (e.g. CO and NO)—a novel strategy for site-directed therapy. This extends to cancer therapy, where metal-based precursors offer the prospect of generating excited-state drugs with new mechanisms of action that complement and augment those of current organic photosensitizers.
“…The introduction of extended conjugation into the amine ligands of square–planar Pt(II) complexes has allowed two-photon activation of ligand exchange using red and near-infrared (NIR) light. Interestingly, the optimum wavelength for two-photon activation of cis -[ PtCl 2 (MOPEP) 2 ], where MOPEP is the π -conjugated ligand 4-[2-(4-methoxyphenyl)ethynyl]pyridine, is shorter than twice the single-photon absorption wavelength [16]. Figure 3.Two-photon absorption (TPA) in the singlet metal-to-ligand charge-transfer ( 1 MLCT) band and subsequent excited-state absorption (ESA) allow highly conjugated ruthenium(II) systems, such as that shown, to be used for their optical power-limiting properties.…”
Section: Light Deliverymentioning
confidence: 99%
“…red light) that penetrate more deeply into tissues. For example, ligand substitution in square–planar Pt II complexes containing conjugated amine ligands can be activated by two-photon absorption, but interestingly, the absorption maximum for one-photon absorption is displaced slightly from the two-photon wavelength [16]. …”
Section: Photo-induced Release Of Bioactive Moleculesmentioning
This short review highlights some of the exciting new experimental and theoretical developments in the field of photoactivatable metal complexes and their applications in biotechnology and medicine. The examples chosen are based on some of the presentations at the Royal Society Discussion Meeting in June 2012, many of which are featured in more detail in other articles in this issue. This is a young field. Even the photochemistry of well-known systems such as metal–carbonyl complexes is still being elucidated. Striking are the recent developments in theory and computation (e.g. time-dependent density functional theory) and in ultrafast-pulsed radiation techniques which allow photochemical reactions to be followed and their mechanisms to be revealed on picosecond/nanosecond time scales. Not only do some metal complexes (e.g. those of Ru and Ir) possess favourable emission properties which allow functional imaging of cells and tissues (e.g. DNA interactions), but metal complexes can also provide spatially controlled photorelease of bioactive small molecules (e.g. CO and NO)—a novel strategy for site-directed therapy. This extends to cancer therapy, where metal-based precursors offer the prospect of generating excited-state drugs with new mechanisms of action that complement and augment those of current organic photosensitizers.
“…As a result, metal complexes with the ability to absorb two photons (usually large with highly conjugated donor and acceptor ligands) can be activated with longer and clinically relevant wavelengths. In a recent report, Zhao et al 56 presented the first example of a Pt(II) complex containing the π-conjugated ligand 4-[2-(4-methoxyphenyl)ethynyl]pyridine for which activation with laser pulses between 600 and 740 nm yielded the same photoproducts as UV activation 56 . Furthermore, research has been carried out on the development of upconversion nanoparticles in PDT.…”
Platinum-based chemotherapeutic drugs such as cisplatin, carboplatin and oxaliplatin are widely applied for the treatment of various types of tumours. Over the last few decades, a large variety of Pt(II) and Pt(IV) complexes have been developed to improve the applicability in a wider spectrum of cancers, increase their therapeutic window and reduce the dose-limiting side effects. Photodynamic therapy (PDT), which is the administration of a photosensitiser followed by visible light activation, is a promising route to avoid damage to healthy cells and the surrounding tissue. Transition metal complexes as photochemotherapeutic agents are an attractive option for further development in the field of photoactivated chemotherapy (PACT). These complexes exhibit different numbers and types of excited states which are easily accessible upon light irradiation, subsequently giving rise to the formation of various photoproducts that can enable a distinct mode of action. Platinum-diazido complexes are promising candidates for PACT due to the low cytotoxicity when irradiated with visible light. This review summarises the mode of action of current platinum anticancer drugs with cisplatin as a lead example and the development of non-conventional Pt(II) complexes. Background information regarding PDT the photophysical and photochemical properties of metal complexes is provided, as well as notable examples of photoactivated metal complexes with biological activity. Particular emphasis is placed on recent developments on platinum photoactivated drugs.
“…The unexpected photodamage to tissues, nucleic acids, proteins, and inefficient light/tissue penetration could potentially hamper the use of short-wavelength lightactivated Pt IV complexes for wide clinical applications. [6] Although two-photon photolysis using long-wavelength excitation has been used to investigate the possibility of ligand substitution in square-planar Pt II complex, [7] the probability of two-photon absorption is typically small and large crosssections of selected ligands are required for the system to be susceptible to longer-wavelength light irradiation. Given the clinical significance of photoactive Pt IV prodrugs, the design of a simple and specific strategy that offers precise control of long-wavelength light activation of Pt IV prodrug complexes specifically to tumor cells with minimum biological damage remains a big challenge.…”
Platinum-based drugs are among the most active antitumor reagents in clinical practice; their application is limited by side effects and drug resistance. A novel and personalized near-infrared (NIR) light-activated nanoplatform is obtained by combining a photoactivatable platinum(IV) prodrug and a caspase imaging peptide conjugated with silica-coated upconversion-luminescent nanoparticles (UCNPs) for the remote control of antitumor platinum prodrug activation, and simultaneously for real-time imaging of apoptosis induced by activated cytotoxicity. Upon NIR light illumination, the Pt(IV) prodrug complex is activated at the surface of the nanoparticle and active components are selectively released which display cytotoxicity against human ovarian carcinoma A2780 cells and its cisplatin-resistant variant A2780cis cells. More importantly, the caspases enzymes triggered by cytotoxicity would effectively cleave the probe peptide, thereby allowing the direct imaging of apoptosis in living cells.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
