Azide-modified corrole phosphorus complexes for endoplasmic reticulum-targeted fluorescence bioimaging and effective cancer photodynamic therapy

Study on corrole photosensitizers (PSs) for photodynamic therapy (PDT) has made remarkable progress. Targeted delivery of PSs is of great significance for enhancing therapeutic efficiency, decreasing the dosage, and reducing systemic toxicity during PDT. The development of PSs that can be specifically delivered to the subcellular organelle is still an attractive and challenging work. Herein, we synthesize a series of azide-modified corrole phosphorus and gallium complex PSs, in which phosphorus corrole 2-P could not only precisely target the endoplasmic reticulum (ER) with a Pearson correlation coefficient (PCC) up to 0.92 but also possesses the highest singlet oxygen quantum yields (ΦΔ = 0.75). This renders it remarkable PDT activity at a very low dosage (IC50 = 23 nM) towards HepG2 tumor cell line while ablating solid tumors in vivo with excellent biosecurity. Furthermore, 2-P exhibits intense red fluorescence (ΦF = 0.25), outstanding photostability, and a large Stokes shift (190 nm), making it a promising fluorescent probe for ER. This study provides a clinically potential photosensitizer for cancer photodynamic therapy and a promising ER fluorescent probe for bioimaging.

Current Progress in Gallium-based Liquid Metals for Combinatory Phototherapeutic Anticancer Applications

A variety of therapeutic approaches using liquid metal (LM) have been intensively investigated, due to its unique physico-chemical properties that include high surface tension, fluidity, shape deformability, thermal conductivity, and electrical conductivity. Among a series of LMs, the relatively lower toxicity and minimal volatility of gallium (Ga)-based LMs (GaLMs) enables their usage in a series of potential biomedical applications, especially implantable platforms, to treat multiple diseases. In addition, the highly efficient conversion of light energy into thermal or chemical energy via GaLMs has led to recent developments in photothermal and photodynamic applications for anticancer treatments. As attractive photothermal agents or photosensitizers, a systematic interpretation of the structural characteristics and photo-responsive behaviors of GaLMs is necessary to develop effective anticancer engineering applications. Therefore, the aim of this review is to provide a comprehensive summary of currently suggested GaLM-mediated photo-therapeutic cancer treatments. In particular, the review summarizes (1) surface coating techniques to form stable and multifunctional GaLM particulates, (2) currently investigated GaLM-mediated photothermal and photodynamic anticancer therapies, (3) synergistic efficacies with the aid of additional interventions, and (4) 3D composite gels embedded with GaLMs particles, to convey the potential technological advances of LM in this field.

Photodynamic antitumor activity of Gallium(III) and Phosphorus(V) complexes of trimethoxyl A2B triaryl corrole

Two new trimethoxyl A₂B triaryl corroles 10-(2,4,6-trimethoxyphenyl)-5,15-bis(pentafluorophenyl)- corrole (1) and 10-(3,4,5-trimethoxyphenyl)-5,15-bis(pentafluorophenyl)-corrole (2) and their gallium(III) and phosphorus(V) (1-Ga, 1-P, 2-Ga and 2-P) complexes had been prepared and well characterized by UV-vis, NMR and HR-MS. Among all compounds, 2-Ga, 1-P and 2-P showed excellent in vivo photodynamic activity against the MDA-MB-231, A549, Hela and HepG2 cell lines upon light irradiation at 625 nm. And 2-P even exhibited higher phototoxicity than the clinical photosensitizer temoporfin. Also, 2-P exhibited the highest singlet oxygen quantum yield and photostability. The preliminary investigation revealed that 2-P could be rapidly absorbed by tumor cells and mainly located in the cytoplasm. After photodynamic therapy (PDT) treatment with 2-P, mitochondrial membrane potential destruction, intracellular ROS level increasing and nuclear fragmentation of cancer cells could be observed. Cell cycle analysis demonstrated that the 2-P PDT may cause tumor cell arrest at sub-G1 stage and induce early and late apoptosis of cells. These results suggest that 2-P is a promising candidate as a photosensitizer for photodynamic therapy.

Reaction of Corroles with Sarcosine and Paraformaldehyde: A New Facet of Corrole Chemistry

Details on the unexpected formation of two new (dimethylamino)methyl corrole isomers from the reaction of 5,10,15-tris(pentafluorophenyl)corrolatogallium(III) with sarcosine and paraformaldehyde are presented. Semi-empirical calculations on possible mechanism pathways seem to indicate that the new compounds are probably formed through a Mannich-type reaction. The extension of the protocol to the free-base 5,10,15-tris(pentafluorophenyl)corrole afforded an unexpected new seven-membered ring corrole derivative, confirming the peculiar behavior of corroles towards known reactions when compared to the well-behaved porphyrin counterparts.

Corroles at work: a small macrocycle for great applications

Corrole chemistry has witnessed an impressive boost in studies in the last 20 years, thanks to the possibility of preparing corrole derivatives by simple synthetic procedures. The investigation of a large number of corroles has highlighted some peculiar characteristics of these macrocycles, having features different from those of the parent porphyrins. With this progress in the elucidation of corrole properties, attention has been focused on the potential for the exploitation of corrole derivatives in different important application fields. In some areas, the potential of corroles has been studied in certain detail, for example, the use of corrole metal complexes as electrocatalysts for energy conversion. In some other areas, the field is still in its infancy, such as in the exploitation of corroles in solar cells. Herein, we report an overview of the different applications of corroles, focusing on the studies reported in the last five years.

β-Bis-CF3-substituted phosphorus corroles, theory and experiments

All constitutional isomers of beta bis-CF3 substituted (tpfc)PF2 were geometrically optimized and studied electronically. The six synthetically accessed compounds were characterized (of the 18 possible) by NMR spectroscopy and other techniques.

Ligand Non-innocence and Single Molecular Spintronic Properties of AgII Dibenzocorrole Radical on Ag(111)

A facile method for the quantitative preparation of silver dibenzo-fused corrole Ag-1 is described. In contrast to the saddle conformation resolved by single-crystal X-ray analysis for Ag-1, it adopts an unprecedented domed geometry, with up and down orientations, when adsorbed on an Ag(111) surface. Sharp Kondo resonances near Fermi level, both at the corrole ligand and the silver center were observed by cryogenic STM, with relatively high Kondo temperature (172 K), providing evidence for a non-innocent Ag^II -corrole^.2- species. Further investigation validates that benzene ring fusion and molecule-substrate interactions play pivotal roles in enhancing Ag(4d(x² -y² ))-corrole (π) orbital interactions, thereby stabilizing the open-shell singlet Ag^II -corrole^.2- on Ag(111) surface. Moreover, this strategy used for constructing metal-free benzene-ring fused corrole ligand gives rise to inspiration of designing novel metal-corrole compound for multichannel molecular spintronics devices.

Photodynamic antitumor activity of Ru(ii) complexes of imidazo-phenanthroline conjugated hydroxybenzoic acid as tumor targeting photosensitizers

Two novel Ru(ii) polypyridyl complexes bearing imidazo-phenanthroline conjugated hydroxybenzoic acid groups were designed to enhance the tumor targeting ability as photosensitizers for photodynamic therapy. [Ru(bpy)2(phcpip)] (ClO4)2 (Ru-1) and [Ru(bpy)2(ohcpip)] (ClO4)2 (Ru-2) (bpy = 2,2'-bipyridine; phcpip = 2-(3-carboxyl-4-hydroxyphenyl) imidazo [4,5-f]phenanthroline; ohcpip = 2-(2-hydroxyl-3-carboxyphenyl) imidazo [4,5-f] [1,10] phenanthroline) were synthesized and their photodynamic antitumor activities were investigated. Both complexes displayed high photocytotoxicity toward cancerous cell lines HepG2, A549, MCF-7, and MDA-MB-231, but low photocytotoxicity toward normal cell lines GES-1 and Huvec. They were mainly localized at the nucleus of HepG2 cells after 24 h incubation, arrested the cell cycle at the G2/M phase and induced cancer cell apoptosis through reactive oxygen species (ROS) mediated pathways. Tumor targeting of the complexes is attributed to stronger molecular binding to DNA.

Halogenated Gallium Corroles:DNA Interaction and Photodynamic Antitumor Activity

A series of halogenated gallium corroles were synthesized and characterized by UV-vis, HRMS, NMR, and FT-IR. The interaction between these gallium corroles and calf thymus DNA had been investigated by spectroscopic methods. These gallium corroles would interact with CT-DNA via an outside binding mode. The photodynamic antitumor activity in vitro of these gallium corroles toward different cell lines had also been tested. 3-Ga displayed low cytotoxicity to normal cells under both light and dark conditions but high phototoxicity to liver cancer cells HepG2. The vitro experiment results showed that 3-Ga could be efficiently absorbed by tumor cells. After light illumination, it may induce reactive oxygen species (ROS) and cause destruction of the mitochondrial membrane potential, which may finally trigger tumor cell apoptosis. Flow cytometry results showed that HepG2 cells were mainly distributed in the sub-G0 phase, which corresponds to cells with highly fragmented DNA or dead cells generally. This suggests that 3-Ga could lead to tumor cell apoptosis after light illumination.

Phosphorus corrole complexes: from property tuning to applications in photocatalysis and triplet-triplet annihilation upconversion

Efficient triplet photosensitizers are important for fundamental photochemical studies and applications such as triplet-triplet annihilation upconversion (TTA UC), photoredox catalytic organic reactions and photovoltaics. We now report a series of phosphorus corrole compounds as efficient visible light-harvesting metal-free triplet photosensitizers. While the heavy-atom-free phosphorus corroles show absorption in the visible spectral region (centered at 573 nm) and have a decent triplet state quantum yield (Φ _Δ = 49%), iodo-substitution on the corrole core induces red-shifted absorption (589 nm) and improves intersystem crossing significantly (Φ _Δ = 67%). Nanosecond transient absorption spectra confirm triplet state formation upon photoexcitation (τ _T = 312 μs) and the iodinated derivatives also display near IR phosphorescence in fluid solution at room temperature (λ _em = 796 nm, τ _p = 412 μs). Both singlet oxygen (¹O₂) and superoxide radical anions (O₂ ^-˙) may be produced with the phosphorus corroles, which are competent photocatalysts for the oxidative coupling of benzylamine (the Aza Henry reaction). Very efficient TTA UC was observed with the phosphorus corroles as triplet photosensitizers and perylene as the triplet acceptor, with upconversion quantum yields of up to Φ _UC = 38.9% (a factor of 2 was used in the equation) and a very large anti-Stokes effect of 0.5 eV.

Intramolecular electron transfer in porphyrin-anthraquinone donor–acceptor systems with varying molecular bridges

Photoinduced electron transfer has been investigated in porphyrin anthraquinone (ZnTTP-AQ) donor–acceptor dyads having either ester (ZnTTP-AQ1) or ether (ZnTTP-AQ2) linkages. Both dyads were characterized by spectroscopic and electrochemical methods. Absorption spectra show absence of any ground state interaction between the porphyrin and anthraquinone moieties. The quenched fluoresence and lifetime indicate electron transfer from the porphyrin to the anthraquinone moiety. The quenching is more pronounced in ZnTTP-AQ1 with ester linkage, suggesting efficient electronic coupling compared to the ether linkage in ZnTTP-AQ2. Computational analysis and frontier molecular orbitals confirmed the formation of charged separated state por[Formula: see text]AQ[Formula: see text]. The electron transfer rates ([Formula: see text] of these triads are found in the range 0.43 × 108 to 10.52 × 109 s[Formula: see text] and are found to be solvent polarity dependent.

“Off–on–off” type of selectively pH-sensing 8-hydroxyquinoline-substituted gallium(iii) corrole

We herein reported the synthesis and pH sensing property of a novel gallium corrole derivatives based on 8-hydroxyquinoline. Ga-corrole derivative showed good fluorescent response upon changing the pH values in the wide region of pH 1 to 12.

Synthesis, characterization and photodynamic activity of Sn(iv) triarylcorroles with red-shifted Q bands

A tin(iv)corrole with meso-thien-2-yl rings has significantly red-shifted Q bands and is found to have favourable photodynamic therapy activity.

Antimicrobial activity and safety applications of meso-tetra(4-pyridyl)platinum(II) porphyrin

Tetra-platinated(II) porphyrin hexafluorophosphate compound (4-PtTPyPor) was synthetized and along 5,10,15,20-tetrakis(4-pyridyl)porphyrin (4-TPyPor), evaluated about the antimicrobial activity and safety. The effect was evaluated with and without light exposition. The antimicrobial activity was analyzed by microdilution and growth curve method. The assays showed an increase of antimicrobial potential caused by porphyrins with light exposition comparing the treatment without light irradiation. The biocompatibility was tested by MTT, ROS production, dsDNA on culture medium and hemolysis. All platinum porphyrin concentrations showed hemolytic activity under light exposition. The ROS measurement doesn't showed statistic difference between treatments and control. The picogreen assay demonstrates a reduction of dsDNA on culture medium with cells treated with porphyrins under light irradiation. The study demonstrated that the platinated porphyrins might be promising microbial photodynamic inactivation with potential applications in wastewater treatment, biofilm control and bioremediation.

DNA-binding, photocleavage and anti-cancer activity of tin(IV) corrole

A new tin(IV) corrole, 5,10,15-tris(4-methoxycarbonylphenyl) corrole tin(IV) (1-Sn) was synthesized and characterized. The DNA binding, photocleavage and anti-cancer activity were studied and compared with its free-base. The interaction of 1-Sn and its free-base 1 with calf thymus DNA had been investigated by spectroscopic methods, viscosity measurements and molecular docking analysis. The results revealed that 1-Sn and 1 could interact with calf thymus DNA via an outside groove binding mode. Furthermore, although 1 displayed no photonuclease activity, 1-Sn exhibited good photonuclease activity as indicated by agarose gel electrophoresis, and superoxide anion might be the active intermediate for the DNA scission. Finally, 1 was nontoxic but 1-Sn displayed cytotoxicity towards A549 tumor cell lines.

Photophysical properties and photodynamic anti-tumor activity of corrole-coumarin dyads

A new non-conjugated corrole-coumarin dyad and its gallium complex has been synthesized. Photophysical properties of the dyads were tested in two solvents, exhibiting strong solvent effect on the absorption and fluorescence spectra. Absorption spectra of the dyads are a linear combination of the spectra of their corresponding monomers, demonstrating a negligible electronic communication between coumarin and corrole moiety. However, fluorescence emission of coumarin entity in all dyads were quenched significantly as compared to pristine coumarin; this was attributed to intramolecular energy transfer from coumarin to the corrole. Photodynamic anti-tumor tests revealed that gallium corrole-coumarin dyads (2-Ga) exhibited good PDT activity towards SiHa cells. After PDT treatment, 2-Ga could induce apoptosis in SiHa cells, which was associated to cell S phase arrest, collapse of the mitochondrial membrane potential and increase of the intracellular ROS level.

Targeted photodynamic therapy of cancer using a novel gallium (III) tris (ethoxycarbonyl) corrole conjugated-mAb directed against cancer/testis antigens 83

Photodynamic therapy (PDT) is a noninvasive, highly selective approach to the treatment of tumors. However, its therapeutic effect is limited by long‐lasting skin phototoxicity. Therefore, to compromise this shortcoming, it is preferable to deliver photosensitizers selectively to tumor cells with the aid of antibodies specific against tumor‐associated antigens. Cancer/testis antigens 83 (CT83), also called KK‐LC‐1 or CXorf61, recognized by cytotoxic T lymphocytes (CTL), has become a promising target for immunotherapy. Herein, we developed and characterized a novel mouse CT83 mAb 7G4 with a high affinity with Gallium (III) 5, 10, 15‐tris (ethoxycarbonyl) corrole (1‐Ga), a new and promising photosensitizer in PDT. The enzyme‐linked immunosorbent assay (ELISA), flow cytometry and cytotoxicity activity assays revealed that 7G4‐1‐Ga was able to recognize human CT83 with high specificity. Furthermore, 7G4‐1‐Ga showed greater cytotoxicity to CT83‐expressing human cancer cells in vitro than 1‐Ga. These results suggest that the antibody‐conjugated photosensitizer between anti‐CT83 mAb and 1‐Ga may have a good application in PDT, where the destruction of CT83‐expressing tumor is required.

trans-A2B-corrole bearing 2,3-di(2-pyridyl)quinoxaline (DPQ)/phenothiazine moieties: synthesis, characterization, electrochemistry and photophysics

Singlet–singlet energy transfer and electron transfer processes in corrole–phenothiazine and corrole–DPQ dyads were demonstrated by using electrochemical and fluorescence (steady-state and time-resolved) spectral studies.

One-Pot Synthesis of Contracted and Expanded Porphyrins with meso-CF3 Groups

Corrole and sapphyrin with the smallest meso-substituents reported so far were prepared in a one-pot synthesis that relies on a non-aldehydic precursor for introducing CF₃ groups. The substantial amounts of products obtained by this facile pathway allowed for the full characterization of 5,10,15-tris(trifluoromethyl)corrole, the access to a variety of stable chelates thereof and investigations that disclose the unique structural and chemical properties induced by the CF₃ substituents. The novel 5,10,15,20-tetra(trifluoromethyl)sapphyrin undergoes only single protonation, which according to its crystal structure is stabilized by favorable non-bonding F/H interaction between the meso-CF₃ and the inverted pyrrolic NH.

Synthesis, characterization and photophysical properties of ferrocenyl and mixed sandwich cobaltocenyl ester linked meso-triaryl corrole dyads

We report here the design and synthesis of corrole-metallocene dyads consisting of a metallocene (either ferrocene (Dyad 1) or mixed sandwich [Formula: see text]-[C[Formula: see text]H[Formula: see text](COOH)]Co([Formula: see text]-C[Formula: see text]Ph[Formula: see text] (Dyad 2)) connected via an ester linkage at meso phenyl position. Both the dyads were characterized by [Formula: see text]H NMR, MALDI-TOF, UV-visible, fluorescence spectroscopies (steady-state, picosecond time-resolved), femtosecond transient absorption spectroscopy (fs-TA) and electrochemical methods. The absorption spectra of these dyads showed slight broadening and splitting of the Soret band that indicates a weak ground state interaction between the corrole macrocycle and metallocene part of the present donor–acceptor (D–A) system. However, in both the dyad systems, fluorescence emission of the corrole was quenched in polar solvents as compared to its parent compound 10-(4-hydroxyphenyl)-5,15-bis-(pentafluorophenyl ) corrole (Ph-Corr). The quenching was more pronounced in ferrocene derivatives than in cobaltocenyl derivatives. Transient absorption studies confirm the absence of photoinduced electron transfer from metallocene to correl for these dyad systems and the quenching of singlet state of corrole is found to enhance intersystem crossing due to heavy atom effect.