Porphyrin photosensitization and phototherapy

Interactions of Mn complexes with DNA: the relevance of therapeutic applications towards cancer treatment

Manganese (Mn) is one of the most significant bio-metals that helps the body to form connective tissue, bones, blood clotting factors, and sex hormones. It is necessary for fat and carbohydrate metabolism, calcium absorption, blood sugar regulation, and normal brain and nerve functions. It accelerates the synthesis of proteins, vitamin C, and vitamin B. It is also involved in the catalysis of hematopoiesis, regulation of the endocrine level, and improvement of immune function. Again, Mn metalloenzymes like arginase, glutamine synthetase, phosphoenolpyruvate decarboxylase, and Mn superoxide dismutase (MnSOD) contribute to the metabolism processes and reduce oxidative stress against free radicals. Recent investigations have revealed that synthetic Mn-complexes act as antibacterial and antifungal agents. As a result, chemists and biologists have been actively involved in developing Mn-based drugs for the treatment of various diseases including cancer. Therefore, any therapeutic drugs based on manganese complexes would be invaluable for the treatment of cancer/infectious diseases and could be a better substitute for cisplatin and other related platinum based chemotherapeutic drugs. From this perspective, attempts have been made to discuss the interactions and nuclease activities of Mn(II/III/IV) complexes with DNA through which one can evaluate their therapeutic applications.

Novel Photodynamic Therapy for Esophageal Squamous Cell Carcinoma following Radiotherapy

Radiotherapy (RT) or chemoradiotherapy (CRT) are frequently selected as treatments for esophageal squamous cell carcinoma (ESCC). However, salvage treatment remains challenging when endoscopic resection is not indicated for residual or recurrent ESCC following RT or CRT. Recently, owing to the emergence of second-generation photodynamic therapy (PDT) using talaporfin sodium, PDT can be performed with less phototoxicity and therefore has regained popularity in the treatment of ESCC. In this study, the effectiveness and safety of second-generation PDT in patients with residual or recurrent ESCC following RT or CRT were examined. Local complete response (L-CR) rates, procedure-related adverse events, and prognosis were evaluated. In 12 patients with 20 ESCC lesions, the L-CR rates were 95.0%. Perforation, postoperative bleeding, and photosensitivity were not observed. Esophageal stricture following PDT developed in one patient, but this could be addressed using balloon dilation. During a median follow-up period of 12 (range, 3-42) months, the 3-year cause-specific survival rate was 85.7%. Even in patients with a Charlson comorbidity index score ≥ 3, the 2-year overall survival rates were 100%. In conclusion, PDT was an efficacious and a safe salvage treatment in patients with local residual or recurrent ESCC following RT or CRT.

A cell membrane-targeting AIE photosensitizer as a necroptosis inducer for boosting cancer theranostics

The exploration of cellular organelle-specific anchoring photosensitizers with both prominent fluorescence imaging behavior and extraordinary reactive oxygen species (ROS) production capability is highly in demand but remains a severe challenge for effective cancer theranostics involving photodynamic therapy (PDT). In this contribution, we developed a cell membrane-targeting and NIR-emission photosensitizer having an aggregation-induced emission (AIE) tendency. The AIE photosensitizer, namely TBMPEI, is capable of lighting up and ablating cancer cells by means of a necroptosis procedure enabling cell membrane rupture and DNA degradation upon light irradiation, endowing TBMPEI with impressive performance for both in vitro and in vivo fluorescence imaging-guided PDT.

Self-assembled semiconducting polymer based hybrid nanoagents for synergistic tumor treatment

There is an impending need for the development of carrier-free nanosystems for single laser triggered activation of phototherapy, as such approach can overcome the drawbacks associated with irradiation by two distinct laser sources for avoiding prolonged treatment time and complex treatment protocols. Herein, we developed a self-assembled nanosystem (SCP-CS) consisting of a new semiconducting polymer (SCP) and encapsulated ultrasmall CuS (CS) nanoparticles. The SCP component displays remarkable near infrared (NIR) induced photothermal ability, enhanced reactive oxygen species (ROS) generation, and incredible photoacoustic (PA) signals upon activation by 808 nm laser for phototherapy mediated cancer ablation. The CuS component improves the PA imaging ability of SCP-CS, and also enhances photo-induced chemodynamic efficacy. Attributed to promoted single laser-triggered hyperthermia and enhanced ROS generation, the SCP-CS nanosystem shows effective intracellular uptake and intratumoral accumulation, enhanced tumor suppression with reduced treatment time, and devoid of any noticeable toxicity.

Photodynamic Therapy for the Treatment and Diagnosis of Cancer-A Review of the Current Clinical Status

Photodynamic therapy (PDT) has been used as an anti-tumor treatment method for a long time and photosensitizers (PS) can be used in various types of tumors. Originally, light is an effective tool that has been used in the treatment of diseases for ages. The effects of combination of specific dyes with light illumination was demonstrated at the beginning of 20th century and novel PDT approaches have been developed ever since. Main strategies of current studies are to reduce off-target effects and improve pharmacokinetic properties. Given the high interest and vast literature about the topic, approval of PDT as the first drug/device combination by the FDA should come as no surprise. PDT consists of two stages of treatment, combining light energy with a PS in order to destruct tumor cells after activation by light. In general, PDT has fewer side effects and toxicity than chemotherapy and/or radiotherapy. In addition to the purpose of treatment, several types of PSs can be used for diagnostic purposes for tumors. Such approaches are called photodynamic diagnosis (PDD). In this Review, we provide a general overview of the clinical applications of PDT in cancer, including the diagnostic and therapeutic approaches. Assessment of PDT therapeutic efficacy in the clinic will be discussed, since identifying predictors to determine the response to treatment is crucial. In addition, examples of PDT in various types of tumors will be discussed. Furthermore, combination of PDT with other therapy modalities such as chemotherapy, radiotherapy, surgery and immunotherapy will be emphasized, since such approaches seem to be promising in terms of enhancing effectiveness against tumor. The combination of PDT with other treatments may yield better results than by single treatments. Moreover, the utilization of lower doses in a combination therapy setting may cause less side effects and better results than single therapy. A better understanding of the effectiveness of PDT in a combination setting in the clinic as well as the optimization of such complex multimodal treatments may expand the clinical applications of PDT.

Inhibition of photodynamic therapy induced-immunosuppression with aminolevulinic acid leads to enhanced outcomes of tumors and pre-cancerous lesions

Photodynamic therapy (PDT) is a treatment option for tumors and pre-cancerous lesions, but it has immunosuppressive side effects that limit its effectiveness. Recent studies suggest that PDT-mediated immunosuppression occurs through a cyclooxygenase type 2 (COX-2) mediated pathway that leads to increases in regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs), which act as negative regulators of immune responses. Given this pathway, there are three main methods to block immunosuppression: i) Inhibiting the proliferation of Tregs, which can be achieved with the administration of cyclophosphamide or inhibitors of indoleamine 2,3-dioxygenase 1, an activator of Tregs; ii) inhibiting MDSCs by reducing hypoxia around the tumor to create an unfavorable environment or administering all-trans-retinoic acid, which converts MDSCs to a non-immunosuppressive state; and iii) inhibiting COX-2 through selective or non-selective COX-inhibitors. In the present review article, strategies that have shown increased efficacy of PDT in treating tumors and pre-cancerous lesions by blocking the immunosuppressive side effects are outlined and discussed.

A review of advanced nanoformulations in phototherapy for cancer therapeutics

Phototherapy has the potential to play a greater role in oncology. Phototherapy converts light energy into either chemical energy or thermal energy, which eventually destroys cancer cells after a series of biological reactions. With nanotechnology applications in cancer therapeutics, it has become possible to prepare smart drug carriers with multifunctional properties at the nanoscale level. These nanocarriers may be able to deliver the drug molecules to the target site more efficiently in the form of nanoparticles. Several intrinsic and extrinsic properties of these nanocarriers help target the tumor cells exclusively, and by utilizing these features, drug molecules can be delivered to the tumor cells specifically, which results in high tumor uptake and better therapeutic effects ultimately. Nanocarriers can also be designed to carry different drugs together to provide a platform for combination therapy like chemo-photodynamic therapy and chemo-photodynamic-photothermal therapy. In combination therapy, co-delivery of all different drugs is crucial to obtain their synergistic effects, and with the help of nanocarriers, it is possible to co-deliver these drugs by loading them together onto the nanocarriers.

Light Sources and Dosimetry Techniques for Photodynamic Therapy

Effective treatment delivery in photodynamic therapy (PDT) requires coordination of the light source, the photosensitizer, and the delivery device appropriate to the target tissue. Lasers, light-emitting diodes (LEDs), and lamps are the main types of light sources utilized for PDT applications. The choice of light source depends on the target location, photosensitizer used, and light dose to be delivered. Geometry of minimally accessible areas also plays a role in deciding light applicator type. Typically, optical fiber-based devices are used to deliver the treatment light close to the target. The optical properties of tissue also affect the distribution of the treatment light. Treatment light undergoes scattering and absorption in tissue. Most tissue will scatter light, but highly pigmented areas will absorb light, especially at short wavelengths. This review will summarize the basic physics of light sources, and describe methods for determining the dose delivered to the patient.

Encapsulation of Gold Nanorods with Porphyrins for the Potential Treatment of Cancer and Bacterial Diseases: A Critical Review

Cancer and bacterial diseases have been the most incidental diseases to date. According to the World Health Report 2018, at least every family is affected by cancer around the world. In 2012, 14.1 million people were affected by cancer, and that figure is bound to increase to 21.6 million in 2030. Medicine therefore sorts out ways of treatment using conventional methods which have been proven to have many side effects. Researchers developed photothermal and photodynamic methods to treat both cancer and bacterial diseases. These methods pose fewer effects on the biological systems but still no perfect method has been synthesized. The review serves to explore porphyrin and gold nanorods to be used in the treatment of cancer and bacterial diseases: porphyrins as photosensitizers and gold nanorods as delivery agents. In addition, the review delves into ways of incorporating photothermal and photodynamic therapy aimed at producing a less toxic, more efficacious, and specific compound for the treatment.

Screening of two-photon activated photodynamic therapy sensitizers using a 3D osteosarcoma model

An in vitro screening platform for high-throughput profiling and comparison of two-photon photodynamic therapy sensitizers was established.

Immunogenic cancer cell death selectively induced by near infrared photoimmunotherapy initiates host tumor immunity

Immunogenic cell death (ICD) is a form of cell death that activates an adaptive immune response against dead-cell-associated antigens. Cancer cells killed via ICD can elicit antitumor immunity. ICD is efficiently induced by near-infrared photo-immunotherapy (NIR-PIT) that selectively kills target-cells on which antibody-photoabsorber conjugates bind and are activated by NIR light exposure. Advanced live cell microscopies showed that NIR-PIT caused rapid and irreversible damage to the cell membrane function leading to swelling and bursting, releasing intracellular components due to the influx of water into the cell. The process also induces relocation of ICD bio markers including calreticulin, Hsp70 and Hsp90 to the cell surface and the rapid release of immunogenic signals including ATP and HMGB1 followed by maturation of immature dendritic cells. Thus, NIR-PIT is a therapy that kills tumor cells by ICD, eliciting a host immune response against tumor.

Efficacy Dependence of Photodynamic Therapy Mediated by Upconversion Nanoparticles: Subcellular Positioning and Irradiation Productivity

Singlet oxygen (¹ O₂ ), as an important kind of reactive oxygen species (ROS) and main therapeutic agent in photodynamic therapy (PDT), only have a half-life of 40 ns and an effective radius of 20 nm, which cause significant obstacles for improving PDT efficacy. In this work, novel upconversion nanoparticle (UCN)-based nanoplatforms are developed with a minimized distance between UCNs and a photosensitizer, protoporphyrin IX (PpIX), and a controllable payload of PpIX, to enhance and control ROS production. The ability of the nanoplatform to target different subcellular organelles such as cell membrane and mitochondria is demonstrated via surface modification of the nanoplatform with different targeting ligands. The results show that the mitochondria-targeting nanoplatforms result in significantly increased capability of both tumor cell killing and inhibition of tumor growth. Subcellular targeting of nanoparticles leads to the death of cancer cells in different manners. However, the efficiency of ROS generation almost have no influence on the tumor cell viability during the period of evaluation. These findings suggest that specific subcellular targeting of the nanoplatforms enhances the PDT efficacy more effectively than the increase of ROS production, and may shed light on future novel designs of effective and controllable PDT nanoplatforms.

Tetrakis(p-Carboranylthio-Tetrafluorophenyl)Chlorin (TPFC): Application for Photodynamic Therapy and Boron Neutron Capture Therapy

Carboranyl-containing chlorins have emerged as promising dual sensitizers for use in both photodynamic therapy (PDT) and boron neutron capture therapy (BNCT), by virtue of their known tumor affinity, low cytotoxicity in dark conditions, and their strong absorptions in the red region of the optical spectrum. Tetrakis(p-carboranylthio-tetrafluorophenyl)chlorin (TPFC) is a new synthetic carboranyl-containing chlorin of high boron content (24% by weight). To evaluate TPFC's applicability as sensitizer for both PDT and BNCT, we performed an in vitro and in vivo study using F98 rat glioma cells and F98 rat glioma-bearing brain tumor models. For the in vivo BNCT study, we used boronophenylalanine (BPA), which is currently used in clinical BNCT studies, via intravenous administration (i.v.) and/or used TPFC via convection-enhanced delivery (CED), a method for local drug infusion directly into the brain. In the in vitro PDT study, the cell surviving fraction following laser irradiation (9J/cm²) was 0.035 whereas in the in vitro BNCT study, the cell surviving fraction following neutron irradiation (thermal neutron=1.73×10¹² n/cm²) was 0.04. In the in vivo BNCT study, the median survival time following concomitant administration of BPA (i.v.) and TPFC (CED) was 42days (95% confidence interval; 37-43days). © 2014 Wiley Periodicals, Inc. and the American Pharmacists Association.

Noncovalent Ruthenium(II) Complexes-Single-Walled Carbon Nanotube Composites for Bimodal Photothermal and Photodynamic Therapy with Near-Infrared Irradiation

To enhance the efficacy and optimize the treatment of cancers, the integration of multimodal treatment strategies leading to synergistic effects is a promising approach. The coassembly of multifunctional agents for systematic therapies has received considerable interest in cancer treatment. Herein, Ru(II) complex-functionalized single-walled carbon nanotubes (Ru@SWCNTs) are developed as nanotemplates for bimodal photothermal and two-photon photodynamic therapy (PTT-TPPDT). SWCNTs have the ability to load a great amount of Ru(II) complexes (Ru1 or Ru2) via noncovalent π-π interactions. The loaded Ru(II) complexes are efficiently released by the photothermal effect of irradiation from an 808 nm diode laser (0.25 W/cm(2)). The released Ru(II) complexes produce singlet oxygen species ((1)O2) upon two-photon laser irradiation (808 nm, 0.25 W/cm(2)) and can be used as a two-photon photodynamic therapy (TPPDT) agent. Based on the combination of photothermal therapy and two-photon photodynamic therapy, Ru@SWCNTs have greater anticancer efficacies than either PDT using Ru(II) complexes or PTT using SWCNTs in two-dimensional (2D) cancer cell and three-dimensional (3D) multicellular tumor spheroid (MCTS) models. Furthermore, in vivo tumor ablation is achieved with excellent treatment efficacy under a diode laser (808 nm) irradiation at the power density of 0.25 W/cm(2) for 5 min. This study examines an efficacious bimodal PTT and TPPDT nanoplat form for the development of cancer therapeutics.

Distribution and retention of rose bengal and disulphonated aluminium phthalocyanine: a comparative study in unicellular eukaryote

Enhanced video-fluorescence microscopy and microspectrofluorometry were used to characterize the internalization, distribution and retention of two photosensitizers, rose bengal--a xanthene dye--and disulphonated aluminium phthalocyanine in eukaryote Paramecium aurelia. Rose bengal, because of its anionic nature, cannot diffuse across the cell membrane and accumulates there preferentially. In a drug-free medium the membrane fluorescence disappears after a few minutes. Complexation of rose bengal with low density lipoproteins gives rise to a different fluorescence pattern, where, in addition to membrane localization and diffuse cytoplasmic fluorescence, highly fluorescent endosomes are observed, which persisted for at least 1 h after drug treatment. Disulphonated aluminium phthalocyanine, on the contrary, seems to be directly internalized through an endocytotic process leading to the appearance of fluorescent endosomes, exhibiting a long persistence, together with cytoplasmic diffuse fluorescence. The presence of low density lipoproteins does not modify the internalization of the drug significantly, because of the very low yield of the complexation reaction. The potential of rose bengal as a photosensitizer for photodynamic therapy is discussed.

G-quadruplex DNA/protoporphyrin IX-based synergistic platform for targeted photodynamic cancer therapy

Photodynamic therapy (PDT) is an emerging technique to induce cancer cell death. However, the tumor specificity, cellular uptake and biodistribution of many photosensitizers urgently need to be improved. In this regard, we show here that the integrated nanoassemblies based on G-quadruplex DNAs (GQDs)/protoporphyrin IX (PPIX) can serve as a synergistic platform for targeted high-performance PDT. In the nanoassemblies, GQDs function as carriers of sensitiser PPIX and confers the system cancer cell targeting ability. After nucleolin-mediated efficient binding and cellular uptake of GQDs/PPIX assemblies, the strong red fluorescence of GQDs/PPIX complex provides a powerful tool for biological imaging. Moreover, the reactive oxygen species (ROS) generated by GQDs/PPIX under light illumination can effectively kill cancer cells. The present approach is simply composed by DNA and photosensitizers, thereby avoiding any complicated and time-consuming covalent modification or chemical labeling procedure.

Synthesis and biological evaluation of new boron-containing chlorin derivatives as agents for both photodynamic therapy and boron neutron capture therapy of cancer

New boron-containing chlorin derivatives 9 and 13 as agents for both photodynamic therapy (PDT) and boron neutron capture therapy (BNCT) of cancer were synthesized from photoprotoporphyrin IX dimethyl ester (2) and L-4-boronophenylalanine-related compounds. The in vivo biodistribution and clearance of 9 and 13 were investigated in tumor-bearing mice. The time to maximum accumulation of compound 13 in tumor tissue was one-fourth of that of compound 9, and compound 13 showed rapid clearance from normal tissues within 24h after injection. The in vivo therapeutic efficacy of PDT using 13 was evaluated by measuring tumor growth rates in tumor-bearing mice with 660 nm light-emitting diode irradiation at 3h after injection of 13. Tumor growth was significantly inhibited by PDT using 13. These results suggested that 13 might be a good candidate for both PDT and BNCT of cancer.

Toward a molecular understanding of the photosensitizer-copper interaction for tumor destruction

The aim of this study was to shown that the photosensitizer in photodynamic therapy (PDT) can contribute to the dark toxicity and phototoxicity of the tumor by binding with copper. This binding process can remove the copper from the body, stopping angiogenesis as well as activating the mechanisms of cell death, such as apoptosis and necrosis. In PDT, this coupling may be considered a new route for fighting cancer in addition to those already known which involve reactive oxygen species.

Enhanced luminescence of photosensitizer-based mesoporous silica nanocomposites via energy transfer from conjugated polymer

A unique assembly approach was developed to fabricate conjugated polymer and photosensitizer-doped mesoporous silica nanoparticles with effective Förster resonance energy transfer (FRET) from poly[(9,9-di(3,30-N,N0-trimethylammonium)-propylfluorenyl-2,7-diyl)-alt-co-(1,4-phenylene)] (PFP) to porphyrin-based photosensitizers (PSs). PFP and silica nanoparticles form a complex through electrostatic interactions, and efficient energy transfer from PFP to porphyrin-based PSs occurs upon irradiation. This approach is stable, effective, and diversified. PS-doped mesoporous silica nanoparticles showed three- to four-fold enhanced emission with the excitation of the maximum absorption wavelength of PS in the presence of PFP in comparison to the case without PFP. Doping fluorescence dyes into the nonporous core and adjusting the content of PS conjugated with the shell can endow the silica nanoparticles with a combinational optical signal of dyes and PS. These silica nanoparticles exhibit further improved performance on the basis of enhanced energy transfer offered by light-harvesting conjugated polymers.

Synthesis and stereochemistry of highly unsymmetric beta,meso-linked porphyrin arrays

Porphyrin arrays with tailor-made photophysical properties and well-defined three-dimensional geometries constitute attractive synthetic targets in porphyrin chemistry. The paper describes a variable, straightforward synthetic procedure for the construction of beta,meso-linked porphyrin multichromophores in good to excellent yields. In a Suzuki-type coupling reaction beta-borylated 5,10,15,20-tetraarylporphyrins (TAPs) served as versatile building blocks for the preparation of a plethora of directly linked, unsymmetrically substituted di- and triporphyrins. Besides their interesting photophysical properties, especially the trimeric porphyrin arrays show exciting stereochemical features. The established protocols thus open a convenient entry into the synthesis of achiral and chiral, unsymmetrically substituted beta,meso-linked oligoporphyrins, e.g., for applications in biomedicine or nonlinear optics.

Experimental studies of photodynamic therapy in a retinoblastoma-like tumour

Combination therapy with a purified hematoporphyrin derivative, Photofrin II, and red light (photodynamic therapy) was investigated in a retinoblastoma-like tumour growing in the eyes of rats in vivo and in cell cultures. There was a marked dose-response relationship between Photofrin II and the light energy both in vitro and in vivo. Up to 33% of the tumours could be controlled in vivo. In vivo/in vitro assays indicated Photofrin II uptake in the tumour cells in vivo in relation to the administered doses. Studies of cell death kinetics suggested that the mechanisms of photodynamic therapy were both a primary cell kill effect and a secondary tissue destruction, probably as a consequence of vascular damage.

Phototocatalytic lithography of poly(propylene sulfide) block copolymers: toward high-throughput nanolithography for biomolecular arraying applications

Photocatalytic lithography (PCL) is an inexpensive, fast, and robust method of oxidizing surface chemical moieties to produce patterned substrates. This technique has utility in basic biological research as well as various biochip applications. We report on porphyrin-based PCL for patterning poly(propylene sulfide) block copolymer films on gold substrates on the micrometer and submicrometer scales. We confirm chemical patterning with imaging ToF-SIMS and low-voltage SEM. Biomolecular patterning on micrometer and submicrometer scales is demonstrated with proteins, protein-linked beads. and fluorescently labeled proteins.

Fluorescence investigation of the binding of model PDT drugs to nonionic and zwitterionic surfactants

The binding of two model photodynamic therapy drugs, chlorin p(6) and purpurin 18, with surfactants has been studied using steady-state and time-resolved fluorescence techniques. The surfactants used are amphiphilic nonionic surfactant (Tween 80 and Tween 40) and zwitterionic surfactant (HAPS). These have applications in drug delivery. The studies have been performed at pH 7 and 5 for chlorin p(6) and at pH 7 for purpurin 18. The binding constants have been estimated from the change in fluorescence parameters and have been compared with those for Cremophor EL and human serum albumin. Chlorin p(6) is found to bind to the surfactants to a greater extent at pH 5 than at pH 7. The same ionic species of chlorin p(6) is found to exist at the maximum concentrations of the surfactants.

Fabrication of ZnPc/protein nanohorns for double photodynamic and hyperthermic cancer phototherapy

Multifunctionalization of carbon nanotubules is easily achieved by attaching functional molecules that provide specific advantages for microscopic applications. We fabricated a double photodynamic therapy (PDT) and photohyperthermia (PHT) cancer phototherapy system that uses a single laser. Zinc phthalocyanine (ZnPc) was loaded onto single-wall carbon nanohorns with holes opened (SWNHox), and the protein bovine serum albumin (BSA) was attached to the carboxyl groups of SWNHox. In this system, ZnPc was the PDT agent, SWNHox was the PHT agent, and BSA enhanced biocompatibility. The double phototherapy effect was confirmed in vitro and in vivo. When ZnPc-SWNHox-BSA was injected into tumors that were subcutaneously transplanted into mice, the tumors almost disappeared upon 670-nm laser irradiation. In contrast, the tumors continued to grow when only ZnPc or SWNHox-BSA was injected. We conclude that carbon nanotubules may be a valuable new tool for use in cancer phototherapy.

Porphyrin-based photocatalytic lithography

Photocatalytic lithography couples light with photoreactive coated mask materials to pattern surface chemistry. We excite porphyrins to create radical species that photocatalytically oxidize, and thereby pattern, chemistries in the local vicinity. The technique advantageously is suited for use with a wide variety of substrates. It is fast and robust, and the wavelength of light does not limit the resolution of patterned features. We have patterned proteins and cells to demonstrate the utility of photocatalytic lithography in life science applications.

Ruthenium porphyrin compounds for photodynamic therapy of cancer

Five 5,10,15,20-tetra(4-pyridyl)porphyrin (TPP) areneruthenium(II) derivatives and a p-cymeneosmium and two pentamethylcyclopentadienyliridium and -rhodium analogues were prepared and characterized as potential photosensitizing chemotherapeutic agents. The biological effects of all these derivatives were assessed on human melanoma tumor cells, and their cellular uptake and intracellular localization were determined. All molecules, except the rhodium complex which was not cytotoxic, demonstrated comparable cytotoxicity in the absence of laser irradiation. The ruthenium complexes exhibited excellent phototoxicities toward melanoma cells when exposed to laser light at 652 nm. Cellular uptake and localization microscopy studies of [Ru 4(eta (6)-C 6H 5CH 3) 4(TPP)Cl 8] and [Rh 4(eta (5)-C 5Me 5) 4(TPP)Cl 8] revealed that they accumulated in the melanoma cell cytoplasm in granular structures different from lysosomes. The fluorescent porphyrin moiety and the metal component were localized in similar structures within the cells. Thus, the porphyrin areneruthenium(II) derivatives represent a promising new class of organometallic photosensitizers able to combine chemotherapeutic activity with photodynamic therapeutic treatment of cancer.

Studies on the interaction between tetraphenylporphyrin compounds and bovine serum albumin

The interaction of three porphyrin compounds with bovine serum albumin (BSA) was examined by fluorescence emission spectra at the excitation wavelength 280 nm and in UV-Vis absorption spectra. Through fluorescence quenching experiments, it was confirmed that the combination of three porphyrin compounds with BSA was a single static quenching process. The binding constant K(A), the thermodynamic parameters enthalpy change (DeltaH(0)), Gibbs free energy change (DeltaG(0)) and entropy change (DeltaS(0)) were obtained. It was found that hydrophobic interaction played a main role in tetraphenylporphyrin (TPP) or tetraparacholophenylporphyrin (TClPP) binding to BSA, while tetraparamethoxyphenylporphyrin (TMEOPP) mainly based on van der Waals' force. According to Föster energy transfer, the separate distance r, the energy transfer efficiency E and Föster radium R(0) were calculated. The results obtained from the above experiments showed that three porphyrin compounds were tightly bound to BSA.

Plasmonic photothermal therapy (PPTT) using gold nanoparticles

The use of lasers, over the past few decades, has emerged to be highly promising for cancer therapy modalities, most commonly the photothermal therapy method, which employs light absorbing dyes for achieving the photothermal damage of tumors, and the photodynamic therapy, which employs chemical photosensitizers that generate singlet oxygen that is capable of tumor destruction. However, recent advances in the field of nanoscience have seen the emergence of noble metal nanostructures with unique photophysical properties, well suited for applications in cancer phototherapy. Noble metal nanoparticles, on account of the phenomenon of surface plasmon resonance, possess strongly enhanced visible and near-infrared light absorption, several orders of magnitude more intense compared to conventional laser phototherapy agents. The use of plasmonic nanoparticles as highly enhanced photoabsorbing agents has thus introduced a much more selective and efficient cancer therapy strategy, viz. plasmonic photothermal therapy (PPTT). The synthetic tunability of the optothermal properties and the bio-targeting abilities of the plasmonic gold nanostructures make the PPTT method furthermore promising. In this review, we discuss the development of the PPTT method with special emphasis on the recent in vitro and in vivo success using gold nanospheres coupled with visible lasers and gold nanorods and silica-gold nanoshells coupled with near-infrared lasers.

Water-Soluble Self-Assembled Butadiyne-Bridged Bisporphyrin: A Potential Two-Photon-Absorbing Photosensitizer for Photodynamic Therapy

We have synthesized a novel, two-photon-absorbing photosensitizer for two-photon-absorption photodynamic therapy (2PA-PDT). The molecule is a butadiyne-bridged porphyrin dimer terminated with two water-soluble porphyrin monomers connected through Zn-imidazolyl self-assembly and covalently linked through olefin metathesis. It has an effective two-photon-absorption (2PA) cross-section value, sigma((2)), of 33 000+/-4600 GM with 5-ns pulses at 890 nm measured by using the open-aperture Z-scan technique. The compound was found to generate singlet oxygen, cytotoxic for tumor cells in photodynamic therapy (PDT), under 2PA conditions by conducting photobleaching experiments with anthracene-9,10-dipropionic acid sodium salt (ADPA).

Diffuse interstellar bands: a comprehensive laboratory study

As a result of the search for the identity of the chromophores responsible for producing the diffuse interstellar bands, a comprehensive exposition of experimental data is presented, which implicates the following molecules: (1) The extremely stable organic molecules, magnesium tetrabenzoporphyrin (MgTBP) and H(2)TBP. (2) A paraffin matrix (referred to as "grains") containing TBPs. (3) A low concentration of pyridine (also within the grains), whose transmission window at 2175 A, accounts for the ubiquitous UV bump. The blue emission spectra associated with the central star, HD44179, of the Red Rectangle displays the fluorescence excitation spectra of bare MgTBP. This unique spectrum matches the low temperature lab data of MgTBP in the vapor phase. An effective grain temperature of 2.728 K (+/-0.008) was deduced, based on MgTBP's lowest measured vibrational state of 341 GHz.

Synthesis and biological evaluation of new pentaphyrin macrocycles for photodynamic therapy

This paper describes the synthesis and in-depth characterization of two new porphyrogenic macrocycles 1 and 2, and provides an evaluation of these molecules as photosensitizer agents. By tuning the reaction conditions and starting from readily available 1,9-diformyl-5-phenyldipyrromethane (4) and tripyrrane dicarboxylic acid (3), both the nonaromatic isopentaphyrin 1, composed of a 24 pi-electron macrocycle, and the aromatic pentaphyrin 2, composed of a 22 pi-electron macrocycle, were obtained in good yield and purity. Confocal laser microscopy and cytofluorimetry studies showed that the newly synthesized pentaphyrins penetrate the cell membranes and localize mainly in the cytoplasm. In the absence of light, 1 and 2 exhibit a nonsignificant cytotoxic effect at concentrations up to 3 mug/mL. In contrast, the synthesized pentaphyrins, when delivered to cells at 1.5 or 3 microg/mL and irradiated with white light (8 mW/cm(2)), promoted a strong and dose-dependent phototoxic effect in four different cell lines. FACS and caspase-3/7 activation assays demonstrated that the pentaphyrins cause cell death by apoptosis.

Photoactivation of pheophorbide a induces a mitochondrial-mediated apoptosis in Jurkat leukaemia cells

The mechanism of cell death by pheophorbide a (Pba) which has been established to be a potential photosensitizer was examined in experimental photodynamic therapy (PDT) on Jurkat cells, a human lymphoid tumor cell line. In 30-60 min after irradiation, Pba treated cells exhibited apoptotic features including membrane blebbing and DNA fragmentation. Pba/PDT caused a rapid release of cytochrome c from mitochondria into the cytosol. Sequentially, activation of caspase-3 and the cleavage of poly ADP-ribose polymerase (PARP) were followed. Meanwhile, no evidence of activation of caspase-8 was indicated in the cells. In experiments with caspase inhibitors, it was found that caspase-3 alone was sufficient initiator for the Pba-induced apoptosis of the cells. Pba specific emission spectra were confirmed in the mitochondrial fraction and the light irradiation caused a rapid change in its membrane potential. Thus, mitochondria were entailed as the crucial targets for Pba as well as a responsible component for the cytochrome c release to initiate apoptotic pathways. Taken together, it was concluded that the mode of Jurkat cell death by Pba/PDT is an apoptosis, which is initiated by mitochondrial cytochrome c release and caspase-3-pathways.

Targeting cells that overexpress the epidermal growth factor receptor with polyethylene glycolated BPD verteporfin photosensitizer immunoconjugates

Photoimmunotherapy was introduced two decades ago but has been studied infrequently in vivo and is virtually untested clinically. Progress has been limited because high-quality, well-characterized photosensitizer immunoconjugates (PICs) have been difficult to make. Here, we describe the development of an innovative conjugation method for producing water-soluble PICs that are free of insoluble aggregates and free of unacceptable amounts of noncovalently associated photosensitizer impurities. The method exploits two procedures previously untried in this research area. First, a small number of antibody lysines (<3 per antibody) are polyethylene glycolated (PEGylated) using a 10 kDa branched polyethylene glycol (PEG), which dramatically enhances PIC solubility and reduces PIC aggregation. Second, a 50% dimethyl sulfoxide-50% aqueous two-solvent system is used to prevent photosensitizer aggregation and noncovalent interactions. These measures allow efficient covalent linkage of the photosensitizer BPD Verteporfin (BPD) to antibody lysines, thorough purification of the resulting PICs (verified by sodium dodecyl sulfate-polyacrylamide gel electrophoresis), maintenance of PIC antigen-binding activity (verified by cellular binding-uptake assays) and reduction of nonspecific cellular uptake (e.g. macrophage capture) of the PICs. Loading levels could be varied controllably in the range < or = 11 BPD/antibody. PICs of the C225 anti-epidermal growth factor receptor (EGFR) chimeric monoclonal antibody killed EGFR-overexpressing A-431 cells photodynamically but did not significantly affect EGFR-negative NR6 cells. Although fluorescence measurements demonstrated that the PICs were quenched by as much as an order of magnitude compared with free BPD, an impressive 90% reduction in A-431 cell viability was achieved using 20 J/cm2 of 690 nm light after a 40 h incubation with the C225 PICs. The results suggest that PEGylated BPD-C225 PICs merit further investigation in animal models of EGFR-overexpressing cancers.