Free-base porphyrin derivatives act as photosensitizers to form singlet oxygen, 1O2, a reactive oxygen species type II, and as such, they can act as antimicrobial agents. We report on an assessment of several neutral and ionic free-base porphyrin derivatives as potential antifungal agents by testing their effects on the crop pathogen Botrytis cinerea (B. cinerea), both in vitro and in vivo. The free-base ionic porphyrins tested impeded the growth of B. cinerea significantly in the 5-30 ppm concentration range when exposed to light but not under dark conditions. This response is consistent with a mechanism involving the photosensitization of 1O2(g), which was confirmed by an observed phosphorescence signal at 1275 nm. Among the free-base porphyrins screened, charged molecules were particularly effective, a property that is associated with their enhanced ability to interact with fungal spores. Interestingly, ionic porphyrins were found to be efficient against various strains of B. cinerea, including those that are resistant to common fungicides, which are routinely used in agriculture. As such, our findings suggest that ionic free-base porphyrin photosensitizers serve as effective and sustainable alternatives to conventional fungicides.

Radiotherapy is the standard treatment for nearly 60 % of cancer patients. Despite advancements such as brachytherapy, stereotactic radiotherapy, and intensity-modulated radiotherapy, further improvements in efficacy and safety are needed. Radiodynamic therapy (RDT) is gaining attention, in which improved radiotherapy outcomes are achieved with the use of porphyrins such as protoporphyrin IX, verteporfin, Mn-porphyrins, and other porphyrinoids such as phthalocyanines and texaphyrins. While the light-based excitation mechanisms of these photosensitizing agents are widely established, their radiosensitization mechanisms remain unclear and underinvestigated. A comprehensive investigation into the observed physicochemical and biological effects of these compounds during radiotherapy enables the identification of several key underlying mechanisms to explain the radiocatalytic properties of porphyrins and porphyrin-related compounds. Porphyrin-like sensitizers can (1) be excited by Cherenkov radiation, (2) be ionized by secondary electrons, (3) initiate redox cycling reactions and enhance reactive oxygen species production, and (4) interfere with critical signaling pathways. These effects may synergistically combine to enhance the effects of ionizing radiation and boost the radiosensitivity of cancer cells, offering a powerful new direction for cancer treatment.

1. Polyacrylamide gel electrophoresis is commonly used to visualize mixtures of proteins, such as those embedded in calcareous biominerals. However, it is ineffective for the detection of biochromes, a major class of low molecular weight organic compounds commonly associated with calcified exoskeletons. 2. We describe a novel approach based on the coupling of electrophoresis and photoluminescence (PL) spectral imaging to reveal invisible biochromes, identify them chemically, provide evidence for their putative interaction with exoskeletal macromolecules and purify them in large amounts. Our protocol relies on three key-steps: a mild extraction of all organics from bleached skeletal powder (step 1); an optimized electrophoretic fractionation immediately followed by direct on-gel spectral image acquisition performed before classical gel staining (step 2); a large-scale purification via preparative electrophoresis coupled to PL spectral imaging, to obtain significant amounts of biochromes of interest (step 3). 3. Steps 1-3 were successfully applied to recent gastropod shell extracts, while steps 1 and 2 were applied to their fossil equivalents from the Eocene epoch (approximate to approximately 45 million years). In both cases, we were able to identify porphyrins associated with the shells via a spectrophotometric measurement of the luminescent bands directly on the analytical gel, even at low concentration in the case of fossil extract. For recent shell extracts, our approach allowed us to identify spectrophotometrically the tubes containing the invisible pigments, after preparative fractionation and fraction collection. 4. Our protocol enables direct on-gel identification of porphyrin molecules, even in trace amounts. It opens up new avenues for studying a wide range of biological composites, whether mineralized or not, that contain photoluminescent biochromes. It is particularly well-suited to ancient specimens and fossils to trace the origin and evolution of biochrome complexes in the geological record.

BACKGROUND:Recent COVID crisis has demonstrated that modern society urgently needs an accessible protection against mass infections, especially viruses, as the new strains are appearing at an ever-increasing pace and cause severe harm to the population and the world economy.METHODS:We have developed an efficient phthalocyanine photosensitizer LASU, that is suitable for dyeing textiles and allows to prepare reusable self-disinfecting fabrics with strong antiviral properties. The safety profile of LASU was evaluated in accredited laboratories by several in vitro assays according to the OECD-guidelines.RESULTS:The textiles impregnated with LASU phthalocyanine showed a significant antiviral photodynamic effect even under moderate indoor and outdoor light. The dye did not show any genotoxic potential in human lymphocyte micronucleus assay. It showed a possible indication for eye irritation in human EpiOcular™ model and was phototoxic when tested in mouse BALB/c 3T3 cell test in the presence and absence of UVA-irradiation.CONCLUSION:Novel phthalocyanine-dyed textiles are suitable for general use as self-disinfecting antiviral barriers and materials in hospitals, households, and public places. The safety profile of LASU is the phototoxic effect which is related to LASU´s mode of action.

Trisubstituted porphyrin derivatives [(TriMPyP)M][Formula: see text]([Formula: see text]) 3 [Formula: see text][Formula: see text] containing three [Formula: see text]-methyl-4-pyridyl ([Formula: see text][Formula: see text] groups were synthesized and characterized electrochemically and spectroscopically in DMSO containing 0.1 M tetrabutylammonium salts. The effect of specific counter-anions, type of metal ion and number of meso-[Formula: see text][Formula: see text] groups on the redox behavior and spectroscopic properties of the neutral and reduced species are examined before and after controlled potential reduction in a thin-layer cell. Each tri-cationic derivative initially undergoes a global two-electron reduction to give a two-banded absorption spectrum with a broad near-IR band ranging from 750–807 nm depending on the type of metal ion. The position of the near-IR band for the doubly reduced porphyrin was also found to correlate with the number of meso-[Formula: see text][Formula: see text] groups on the macrocycle which varied from 1 to 4 while the first reduction potential remained essentially unchanged upon going from macrocycles with two to three to four meso-[Formula: see text][Formula: see text] groups.

New heterogeneous porous materials based on 5,10,15,20-(tetraphenyl)porphyrin (H 2 TPP), 5,10,15,20-(tetra-N-methyl-4-pyridyl)porphyrin tetrachloride (H 2 TNMPyP), zinc(II) 5,10,15,20-(tetra-N-methyl-4-pyridyl)porphyrin tetrachloride (ZnTNMP y P), 5,10,15,20-(tetra-4-carboxyphenyl)porphyrin (H 2 TCPP) and zinc(II)5,10,15,20-(tetra-4-carboxyphenyl)porphyrin (ZnTCPP) have been incorporated into mesoporous silica MCM-41 from slow diffusion of solutions containing different concentrations of porphyrin chromophores. Successful incorporation of all porphyrins has been confirmed by UV-Vis spectroscopy and TGA. XRD patterns of these silica-based host-guest samples prove that the mesoporous structure of MCM-41 remains unchanged after encapsulation. The potential abilities of these photosensitizers to form singlet oxygen ( 1 O[Formula: see text] at the solid state/air interface after light excitation were investigated. Despite the variable amount of encapsulated porphyrin derivatives (based on UV-vis assessment and chemical analysis), the phosphorescence intensity of 1 O 2 peak at 1270 nm remains relatively the same from one composite to the other meaning that the photosensitizers are mainly placed at the surface of the MCM-41 particles.

Examples of photoluminescence (PL) are being reported with increasing frequency in a wide range of organisms from diverse ecosystems. However, the chemical basis of this PL remains poorly defined, and our understanding of its potential ecological function is still superficial. Among mammals, recent analyses have identified free-base porphyrins as the compounds responsible for the reddish ultraviolet-induced photoluminescence (UV-PL) observed in the pelage of springhares and hedgehogs. However, the localization of the pigments within the hair largely remains to be determined. Here, we use photoluminescence multispectral imaging emission and excitation spectroscopy to detect, map, and characterize porphyrinic compounds in skin appendages in situ. We also document new cases of mammalian UV-PL caused by free-base porphyrins in distantly related species. Spatial distribution of the UV-PL is strongly suggestive of an endogenous origin of the porphyrinic compounds. We argue that reddish UV-PL is predominantly observed in crepuscular and nocturnal mammals because porphyrins are photodegradable. Consequently, this phenomenon may not have a specific function in intra- or interspecific communication but rather represents a byproduct of potentially widespread physiological processes.

The use of a single component porphyrin thin-film for photodynamic antimicrobial chemotherapy is unexplored. Herein, a porphyrin with good film formation properties is used to make thin layers, by physical vapor phase deposition, that are stable in aqueous media and can generate singlet oxygen upon 650 nm excitation. The synthesis and photophysical studies, in solution and as thin film, of free base 5,10,15,20-tetra-(4-hexyloxyphenyl)porphyrin are described. The porphyrin was synthesized via modified Adler-Longo conditions. Thin films of this porphyrin were made on quartz glass via spin coating and via vapour-phase deposition. The porphyrin was studied, in solution and as thin film (without a polymer component or matrix), with UV-Vis spectroscopy and with steady-state and time-resolved photoluminescence spectroscopy. The spin coated films display sharp J-band emission at 741 nm, indicating J-aggregate formation, but are not stable in aqueous media. The thin films obtained via vapour-phase deposition do not show the J-band emission, but are stable. The detection of singlet oxygen generated by the porphyrin thin film using a chemiluminescent water-soluble singlet oxygen probe is reported.

Photodynamic Inactivation is an innovative technique used to combat bacterial and viral infections which involves the use of photosensitizing agents along with light to generate cytotoxic reactive oxygen species able to kill bacteria and viruses. In the first section of this minireview, porphyrin-based fluorophores are shown to be remarkable dye candidates for PDI (photodynamic inactivation) applications. The second section is dedicated to the description of porphyrin-based antimicrobial materials and their potentialities for industrial applications such as in food packaging or antimicrobial medical devices and hygiene. Finally, the failings and perspectives of PDI are analyzed to demonstrate how the PDI technique could be an efficient and ecologically friendly antimicrobial technique.

The derivatives of 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) are pivotal ingredients for a large number of functional, stimuli-responsive materials and therapeutic molecules based on their photophysical properties, and there is a urgent need to understand and predict their optical traits prior to investing a large amount of resources in preparing them. Density functional theory (DFT) and time-dependent DFT (TDDFT) computations were performed to calculate the excitation energies of the lowest-energy singlet excited state of a large series of common BODIPY derivatives employing various functional aiming at the best possible combination providing the least deviations from the experimental values. Using the common "fudge" correction, a series of combinations was investigated, and a methodology is proposed offering equal or better performances than what is reported in the literature.

Spectacular photoluminescence (PL) phenomena have been increasingly reported in various organisms from diverse ecosystems. However, the chemical basis of this PL remains poorly defined, and its potential ecological function is still blurry, especially in mammals. Here we used state-of-the-art spectroscopy and multispectral imaging techniques to document new cases of mammalian ultraviolet-induced PL (UV-PL) and to identify free-base porphyrins and natural derivatives as the organic compounds responsible for the reddish luminescence observed in the hairs and spines of distantly related species. We argue that pink to red UV-PL is predominantly observed in crepuscular and nocturnal mammals because porphyrins are photodegradable, and that this phenomenon might not have a specific function in intra- or interspecific communication but consists of a byproduct of a widespread physiological condition, overlooked in mammals.Co-first authors: Séverine Toussaint and Jasper Ponstein

X-ray-induced photodynamic therapy is based on the energy transfer from a nanoscintillator to a photosensitizer molecule, whose activation leads to singlet oxygen and radical species generation, triggering cancer cells to cell death. Herein, we synthesized ultra-small nanoparticle chelated with Terbium (Tb) as a nanoscintillator and 5-(4-carboxyphenyl succinimide ester)-10,15,20-triphenyl porphyrin (P1) as a photosensitizer (AGuIX@Tb-P1). The synthesis was based on the AGuIX@ platform design. AGuIX@Tb-P1 was characterised for its photo-physical and physico-chemical properties. The effect of the nanoparticles was studied using human glioblastoma U-251 MG cells and was compared to treatment with AGuIX@ nanoparticles doped with Gadolinium (Gd) and P1 (AguIX@Gd-P1). We demonstrated that the AGuIX@Tb-P1 design was consistent with X-ray photon energy transfer from Terbium to P1. Both nanoparticles had similar dark cytotoxicity and they were absorbed in a similar rate within the cells. Pre-treated cells exposure to X-rays was related to reactive species production. Using clonogenic assays, establishment of survival curves allowed discrimination of the impact of radiation treatment from X-ray-induced photodynamic effect. We showed that cell growth arrest was increased (35%-increase) when cells were treated with AGuIX@Tb-P1 compared to the nanoparticle doped with Gd.

Water-soluble cationic porphyrins have been shown to possess promising therapeutic potential, through biochemical processes. which depend on solubility as well as the extent of aggregation. under biological conditions. These properties are influenced by a multitude of factors the most important of which are the number of positively charged meso-substituents, the type of counteranion, the central metal ion and the solvent. We have previously investigated mono- di- and tetra-methylpyridyl porphyrins with mainly Cl- counterions and we now turn our attention to trisubstituted derivatives of the type shown at the bottom of the figure. These six new tricationic porphyrins represented as [(TriMPyP)M]3+X- 3 (where M = 2H, ZnII or PdII and X- = Cl- or Tosyl-) containing three N-methyl-4-pyridyl groups and chloride or tosylate counteranions were electrochemically and spectroscopically characterized for the first time. The physicochemical properties of the [(TriMPyP)M]3+X- 3 complexes were compared, under the same solution conditions, to several free base and metal tetracationic porphyrins shown at the top of the figure and represented as [(TMPyP)M]4+X- 4 (where M = 2H, MnIII, FeIII, CoII, ZnII or PdII). Figure 1

Photodynamic therapy is an innovative approach to treat diverse cancers and diseases that involves the use of photosensitizing agents along with light of an appropriate wavelength to generate cytotoxic reactive oxygen species. Among the collection of potential dye candidates, porphyrinoids ( i.e. porphyrins, chlorins, and phthalocyanines) are probably the most promising photosensitizers for PDT applications. This review shows the great potential of these derivatives for their industrial development in the field of health through different applications in photodynamic therapy (PDT), photoimmunotherapy (PIT), ophthalmology, dermatology and photodynamic inactivation (PDI). The purpose of this survey is also to show the new trends and evolutions in these fields.

Selective nucleotide recognition for biosensor evolution requires rational probe design toward the binding-pattern-susceptible readout but without serious poison in selectivity from the context sequences. In this work, we synthesized a dual-function (trihydroxyphenyl)porphyrin (POH3) to target the abasic site (AP site) in ds-DNA using the trihydroxyphenyl substituent and the tetrapyrrole macrocycle as the recognition unit (RU) and the fluorescent signal unit (SU), respectively. RU and SU are separated from each other but are prototropically allosteric. We found that an appropriate pH favors formation of the nonfluorescent quinine/pyrrole (O-NH) conformer of POH3. However, the complementary hydrogen bonding of RU in O-NH with the target cytosine opposite the AP site switches on the SU fluorescence through prototropic allostery toward the phenol/isopyrrole (OH-N) conformer, while the bases thymine, guanine, and adenine totally silence this allostery, suggesting a superb selectivity in single-nucleotide polymorphism (SNP) analysis. The role of the prototropic allostery in achieving such SNP selectivity is also evidenced using porphyrins with other hydroxyl substituent patterns. Because of the SU separation from RU, SU is not directly involved in the interaction with the AP site, and thus, the turn-on selectivity is also realized for DNA with flanking guanine, the most easily oxidized base in DNA. This tolerance to the flanking base identity has seldom been achieved in previous studies. Additionally, other DNA structures cannot bring this allostery, indicating that the combination recipe of the AP site design and the prototropically allosteric probe will find wide applications in DNA-based sensors.

The electrochemical oxidation of zinc(II) 5,15-p-ditolyl-10-phenylporphyrin at its first oxidation potential leads to the formation of the corresponding meso-meso porphyrin dimer as the main product. The number of electrons abstracted, the addition of the hindered base 2,6-lutidine as well as operating in DMF, instead of a CH2Cl2/CH3CN mixture are the key parameters to obtain high yields of the desired coupling product. Indeed, when the electrolyses are carried out in the CH2Cl2/CH3CN mixture, the unexpected zinc(II) 5-chloro-10,20-p-ditolyl-15-phenyl porphyrin is produced as a by-product, the chlorine atom originating from the CH2Cl2 solvent. The monomer and the dimer are characterised by electrochemical analysis. The signature of the dimer is clearly distinguished on the cyclic voltammogram of the monomer on condition of the prior addition of 2,6-lutidine as a hindered base, indicating that the dimerisation process is thus strongly accelerated. Besides, unprecedented X-ray crystallographic structures of the monomer and the meso-meso dimer are presented and their respective structural parameters are compared.

Three face-to-face biscobalt bisporphyrin dyads, including one incorporating a copper(II) ion inside the linker, were synthesized and characterized both spectroscopically and electrochemically in three non-aqueous solvents, dichloromethane, benzonitrile and pyridine. The electrocatalytic reduction of dioxygen with these derivatives on an electrode surface in 1.0 M HClO4 was also investigated and the results are compared to that obtained with "regular" Pacman biscobalt bisporphyrins under the same experimental conditions. Surprisingly, the tris-metal species ( Cu-bisCo ) catalyzes the reduction of O2 mainly via a 2e- transfer process, leading to H2O2 , while the bis-metal (bisCo) catalyst produces H2O via a four electron, four proton process.

A manganese(IV)-oxo porphyrin catalyzes C-C bond formation between zinc porphyrins at the meso-position with a two-electron oxidant to afford the meso-meso linked porphyrin dimer efficiently. The meso-meso linked dimer is formed via formation of the porphyrin radical cation, and the rate-determining step in the catalytic cycle is the formation of a manganese(IV)-oxo porphyrin with a two-electron oxidant.