Intramitochondrial dyes allow selective in vitro photolysis of carcinoma cells

Targeting Mitochondria for Cancer Treatment

There is an increasing accumulation of data on the exceptional importance of mitochondria in the occurrence and treatment of cancer, and in all lines of evidence for such participation, there are both energetic and non-bioenergetic functional features of mitochondria. This analytical review examines three specific features of adaptive mitochondrial changes in several malignant tumors. The first feature is characteristic of solid tumors, whose cells are forced to rebuild their energetics due to the absence of oxygen, namely, to activate the fumarate reductase pathway instead of the traditional succinate oxidase pathway that exists in aerobic conditions. For such a restructuring, the presence of a low-potential quinone is necessary, which cannot ensure the conventional conversion of succinate into fumarate but rather enables the reverse reaction, that is, the conversion of fumarate into succinate. In this scenario, complex I becomes the only generator of energy in mitochondria. The second feature is the increased proliferation in aggressive tumors of the so-called mitochondrial (peripheral) benzodiazepine receptor, also called translocator protein (TSPO) residing in the outer mitochondrial membrane, the function of which in oncogenic transformation stays mysterious. The third feature of tumor cells is the enhanced retention of certain molecules, in particular mitochondrially directed cations similar to rhodamine 123, which allows for the selective accumulation of anticancer drugs in mitochondria. These three features of mitochondria can be targets for the development of an anti-cancer strategy.

Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction Using Deep Eutectic Solvents (DESs) for Neutral Red Dye Spectrophotometric Determination

Deep eutectic solvents (DES), which have low toxicity and are low cost, biodegradable, and easily synthesized, were used for the extraction of neutral red (NR) dye before its spectrophotometric analysis. DES, containing choline chloride as a hydrogen bond acceptor and phenol as a hydrogen bond donor with a molar ratio of 1:2, was used for the extraction of NR dye from aqueous media. The possible interaction of different DESs with NR was studied using density functional theory (DFT) calculations. Experimentally, a UV-visible spectrophotometer was used for the quantitative analysis. The most important parameters affecting method performance, such as pH, extraction temperature, DES type, its volume, THF volume, sonication time, and centrifugation time, were optimized. The developed method provides exceptional sensitivity in terms of LOD and LOQ, which were 2.2 and 7.3 µg/L respectively. The relative standard deviation was 1.35−1.5% (n = 10), and the pre-concentration factor was 40. The method was found to be linear in the range of 2−300 µg/L (R2 = 0.9967). The method was successfully used for the determination of NR in wastewater samples. Finally, the DES-based method presents operational simplicity, high sensitivity, and rapid determination (<5 min) compared with other analytical procedures.

J, M.D.P. DE. C, RAJENDRAM S. Photodynamic Therapy : An Overview and Insights into a Prospective Mainstream Anticancer Therapy

Photodynamic therapy (PDT) procedure has minimum invasiveness in contrast to conventional anticancer surgical procedures. Although clinically approved a few decades ago, it is not commonly used due to its poor efficacy, mainly due to poor light penetration into deeper tissues. PDT uses a photosensitizer (PS), which is photoactivated on illumination by light of appropriate wavelength and oxygen in the tissue, leading to a series of photochemical reactions producing reactive oxygen species (ROS) triggering various mechanisms resulting in lethal effects on tumor cells. This review looks into the fundamental aspects of PDT, such as photochemistry, photobiological effects, and the current clinical applications in the light of improving PDT to become a mainstream therapeutic procedure against a broad spectrum of cancers and malignant lesions. The side effects of PDT, both early and late-onset, are elaborated on in detail to highlight the available options to minimize side effects without compromising therapeutic efficacy. This paper summarizes the benefits, drawbacks, and limitations of photodynamic therapy along with the recent attempts to achieve improved therapeutic efficacy via monitoring various cellular and molecular processes through fluorescent imagery aided by suitable biomarkers, prospective nanotechnology-based targeted delivery methods, the use of scintillating nanoparticles to deliver light to remote locations and also combining PDT with conventional anticancer therapies have opened up new dimensions for PDT in treating cancers. This review inquires and critically analyses prospective avenues in which a breakthrough would finally enable PDT to be integrated into mainstream anticancer therapy.

Application of dimensional analysis in sorption modeling of the styryl pyridinium cationic dyes on reusable iron based humic acid coated magnetic nanoparticles

Cationic dyes exist in various industrial wastewaters and removal prior to discharge is necessary due to their carcinogenic behavior which poses a serious threat to human health. Iron based humic acid coated magnetic nanoparticles (HA-MNPs) were evaluated for the removal of 2-[4-(dimethylamino) styryl]-1-methylpyridinium iodide (2-ASP) as a model compound for cationic styryl pyridinium dyes from aqueous media. HA-MNPs were prepared by co-precipitation and characterized. The adsorption of 2-ASP, measured by fluorescence, demonstrates HA-MNPs are efficient for the 2-ASP removal with a maximum adsorption capacity of ~8 mg/g. Kinetic behavior and equilibrium studies showed the adsorption process fits with pseudo 2nd order and Langmuir isotherm models. The adsorption is relatively fast with ~70% of the adsorption complete within 30 min. The overall removal increases by increasing solution pH. The observed increase in adsorption can be assigned to an enhanced electrostatic attraction between the positively charged 2-ASP and the increase in the negative charge on the HA-MNPs surface as a function of increasing solution pH. Effective and repetitive regeneration of the HA-MNPs was achieved using NaOH treatment of saturated sorbent. Regeneration of HA-MNPs showed that removal efficiency remains consistently high after five consecutive cycles. Dimensional analysis suggested that initial concentration/sorbent dose ratio should be considered for accurate sorption modeling confirmed by experimental data. Then generalized empirical models for isothermal study and removal efficiency prediction were accurately deduced. This finding will help researchers in sorption studies to design their experiments more efficiently and to develop improved empirical models in removal prediction.

Berberine Photo-Activation Potentiates Cytotoxicity in Human Astrocytoma Cells through Apoptosis Induction

Photodynamic therapy (PDT) has recently attracted interest as an innovative and adjuvant treatment for different cancers including malignant gliomas. Among these, Glioblastoma (GBM) is the most prevalent neoplasm in the central nervous system. Despite conventional therapeutic approaches that include surgical removal, radiation, and chemotherapy, GBM is characterized by an extremely poor prognosis and a high rate of recurrence. PDT is a physical process that induces tumor cell death through the genesis and accumulation of reactive oxygen species (ROS) produced by light energy interaction with a photosensitizing agent. In this contribution, we explored the potentiality of the plant alkaloid berberine (BBR) as a photosensitizing and cytotoxic agent coupled with a PDT scheme using a blue light source in human established astrocytoma cell lines. Our data mainly indicated for the combined BBR-PDT scheme a potent activation of the apoptosis pathway, through a massive ROS production, a great extent of mitochondria depolarization, and the sub-sequent activation of caspases. Altogether, these results demonstrated that BBR is an efficient photosensitizer agent and that its association with PDT may be a potential anticancer strategy for high malignant gliomas.

Uptake of micropollutant-bisphenol A, methylene blue and neutral red onto a novel bagasse-β-cyclodextrin polymer by adsorption process

The presence of emerging micropollutants and dyes in water resource has raised global concern about their intense effects to aquatic environments, ecosystem and human health in general. So far, various adsorbents have been suggested for reducing the levels of bisphenol A, methylene blue and neutral red contamination in wastewaters. However, a number of these adsorbents seemed to have low adsorptive capacities and regeneration performances. In view of these, batch experiment was performed to decontaminate these pollutants from aqueous solutions using an optimized bagasse-β-cyclodextrin polymer (SB-β-CD). Characterization studies of SB-β-CD were performed using FTIR, pH point of zero charge, XRD and BET methods. Adsorption of BPA, MB and NR was favored at lower temperature (298 K) and pH of 7.0, 9.0 and 6.0, respectively. The maximum adsorption capacity of BPA, MB and NR at 298 K was 121, 963 and 685 mg g^-1, respectively. Hydrogen bonding through host-guest inclusion and electrostatic interactions could respectively attribute to uptake of BPA and MB/NR onto SB-β-CD. Adsorption kinetics of three pollutants followed pseudo-second-order model. Langmuir and Freundlich models were fitted to describe the adsorption of BPA and MB/NR, respectively. Thermodynamic parameters confirmed the occurrence of physical adsorption which is spontaneous and exothermic in nature. SB-β-CD loaded with BPA and MB/NR was certainly reused by 75% ethanol and 0.1 mol L^-1 HCl solutions, respectively. Novel SB-β-CD showed better adsorptive capacity and regeneration performances; consequently can offers practical application for removal of BPA, MB and NR from wastewaters.

Rational design of block copolymer self-assemblies in photodynamic therapy

Photodynamic therapy is a technique already used in ophthalmology or oncology. It is based on the local production of reactive oxygen species through an energy transfer from an excited photosensitizer to oxygen present in the biological tissue. This review first presents an update, mainly covering the last five years, regarding the block copolymers used as nanovectors for the delivery of the photosensitizer. In particular, we describe the chemical nature and structure of the block copolymers showing a very large range of existing systems, spanning from natural polymers such as proteins or polysaccharides to synthetic ones such as polyesters or polyacrylates. A second part focuses on important parameters for their design and the improvement of their efficiency. Finally, particular attention has been paid to the question of nanocarrier internalization and interaction with membranes (both biomimetic and cellular), and the importance of intracellular targeting has been addressed.

A simple mitochondrial targeting AIEgen for image-guided two-photon excited photodynamic therapy

Two-photon excited photodynamic therapy (TP-PDT) is not only able to offer deeper penetration depth but also much more precise 3D treatment than traditional one-photon excited PDT. However, the achievement of TP-PDT requires photosensitizers with large two-photon absorption cross sections, efficient generation of reactive oxygen species, and bright two-photon fluorescence. In this work, we present a simple AIE luminogen (AIEgen), IQ-TPA, with mitochondrial targeting and susceptible two-photon excitation for image-guided photodynamic therapy in cancer cells. This feasibility of utilizing small molecular multifunctional AIEgens for TP-PDT was demonstrated together with the merits of tiny size, good cell permeability, low dark cytotoxicity and easy synthesis, showing great potential for the development of future theranostic systems.

Photodynamic Efficiency: From Molecular Photochemistry to Cell Death

Photodynamic therapy (PDT) is a clinical modality used to treat cancer and infectious diseases. The main agent is the photosensitizer (PS), which is excited by light and converted to a triplet excited state. This latter species leads to the formation of singlet oxygen and radicals that oxidize biomolecules. The main motivation for this review is to suggest alternatives for achieving high-efficiency PDT protocols, by taking advantage of knowledge on the chemical and biological processes taking place during and after photosensitization. We defend that in order to obtain specific mechanisms of cell death and maximize PDT efficiency, PSes should oxidize specific molecular targets. We consider the role of subcellular localization, how PS photochemistry and photophysics can change according to its nanoenvironment, and how can all these trigger specific cell death mechanisms. We propose that in order to develop PSes that will cause a breakthrough enhancement in the efficiency of PDT, researchers should first consider tissue and intracellular localization, instead of trying to maximize singlet oxygen quantum yields in in vitro tests. In addition to this, we also indicate many open questions and challenges remaining in this field, hoping to encourage future research.

Development of Photodynamic Antimicrobial Chemotherapy (PACT) for Clostridium difficile

BACKGROUND

Clostridium difficile is the leading cause of antibiotic-associated diarrhoea and pseudo membranous colitis in the developed world. The aim of this study was to explore whether Photodynamic Antimicrobial Chemotherapy (PACT) could be used as a novel approach to treating C. difficile infections.

METHODS

PACT utilises the ability of light-activated photosensitisers (PS) to produce reactive oxygen species (ROS) such as free radical species and singlet oxygen, which are lethal to cells. We screened thirteen PS against C. difficile planktonic cells, biofilm and germinating spores in vitro, and cytotoxicity of effective compounds was tested on the colorectal adenocarcinoma cell-line HT-29.

RESULTS

Three PS were able to kill 99.9% of bacteria in both aerobic and anaerobic conditions, both in the planktonic state and in a biofilm, after exposure to red laser light (0.2 J/cm2) without harming model colon cells. The applicability of PACT to eradicate C. difficile germinative spores indirectly was also shown, by first inducing germination with the bile salt taurocholate, followed by PACT.

CONCLUSION

This innovative and simple approach offers the prospect of a new antimicrobial therapy using light to treat C. difficile infection of the colon.

Photodynamic therapy in colorectal cancer treatment--The state of the art in preclinical research

BACKGROUND

Photodynamic therapy (PDT) is used in many different oncologic fields. Also in gastroenterology, where have been a few attempts to treat both the premalignant lesion and advanced colorectal cancer (CRC). This review aims to give a general overview of preclinical photodynamic studies related to CRC cells and animal studies of photodynamic effects related to CRC treatment to emphasize their potential in study of PDT mechanism, safety and efficiency to translate these results into clinical benefit in CRC treatment.

MATERIALS AND METHOD

Literature on in vitro preclinical photodynamic studies related to CRC cells and animal studies of photodynamic effects related to CRC treatment with the fallowing medical subject headings search terms: colorectal cancer, photodynamic therapy, photosensitizer(s), in vitro, cell culture(s), in vivo, animal experiment(s). The articles were selected by their relevance to the topic.

RESULTS

The majority of preclinical studies concerning possibility of PDT application in colon and rectal cancer is focused on phototoxic action of photosensitizers toward cultured colorectal tumor cells in vitro. The purposes of animal experiments are usually elucidation of mechanisms of observed photodynamic effects in scale of organism, estimation of PDT safety and efficiency and translation of these results into clinical benefit.

CONCLUDING REMARKS

In vitro photodynamic studies and animal experiments can be useful for studies of mechanisms and efficiency of photodynamic method as a start point on PDT clinical research. The primary disadvantage of in vitro experiments is a risk of over-interpretation of their results during extrapolation to the entire CRC.

Malachite green interacts with the membrane skeletal protein, spectrin

Energy minimized complex of MG with the self association domain of spectrin.

Mechanisms in photodynamic therapy: part one-photosensitizers, photochemistry and cellular localization

The use of non-toxic dyes or photosensitizers (PS) in combination with harmless visible light that is known as photodynamic therapy (PDT) has been known for over a hundred years, but is only now becoming widely used. Originally developed as a tumor therapy, some of its most successful applications are for non-malignant disease. In a series of three reviews we will discuss the mechanisms that operate in the field of PDT. Part one discusses the recent explosion in discovery and chemical synthesis of new PS. Some guidelines on how to choose an ideal PS for a particular application are presented. The photochemistry and photophysics of PS and the two pathways known as Type I (radicals and reactive oxygen species) and Type II (singlet oxygen) photochemical processes are discussed. To carry out PDT effectively in vivo, it is necessary to ensure sufficient light reaches all the diseased tissue. This involves understanding how light travels within various tissues and the relative effects of absorption and scattering. The fact that most of the PS are also fluorescent allows various optical imaging and monitoring strategies to be combined with PDT. The most important factor governing the outcome of PDT is how the PS interacts with cells in the target tissue or tumor, and the key aspect of this interaction is the subcellular localization of the PS. Examples of PS that localize in mitochondria, lysosomes, endoplasmic reticulum, Golgi apparatus and plasma membranes are given. Finally the use of 5-aminolevulinic acid as a natural precursor of the heme biosynthetic pathway, stimulates accumulation of the PS protoporphyrin IX is described.

Synthesis and characterization of near-infrared absorbing water soluble squaraines and study of their photodynamic effects in DLA live cells

Here, we report the synthesis, photophysical properties and photodynamic effects in DLA live cells of three water soluble squaraine dyes, viz. bisbenzothiazolium squaraine dyes SQMI and SQDI with iodine in one and both benzothiazolium units, respectively, and an unsymmetrical squaraine dye ASQI containing iodinated benzothiazolium and aniline substituents. The diiodinated SQDI showed an anomalous trend in both fluorescence and triplet quantum yields over the monoiodinated SQMI, with SQDI showing higher fluorescence and lower triplet quantum yields compared to SQMI. Nanosecond laser flash photolysis of SQDI and SQMI indicated the formation of triplet excited states with quantum yield of 0.19 and 0.26, respectively. On photoirradiation, both the SQDI and SQMI generate singlet oxygen and it was observed that both dyes undergoing oxidation reactions with the singlet oxygen generated. ASQI which exhibited a lower triplet quantum yield of 0.06 was, however, stable and did not react with the singlet oxygen generated. In vitro cytotoxicity studies of these dyes in DLA live cells were performed using Trypan blue dye exclusion method and it reflect an order of cytotoxicity of SQDI>SQMI>ASQI. Intracellular generation of the ROS was confirmed by dichlorofluorescein assay after the in vitro PDT.

Dye-enhanced multimodal confocal imaging as a novel approach to intraoperative diagnosis of brain tumors

Intraoperative diagnosis plays an important role in accurate sampling of brain tumors, limiting the number of biopsies required and improving the distinction between brain and tumor. The goal of this study was to evaluate dye-enhanced multimodal confocal imaging for discriminating gliomas from nonglial brain tumors and from normal brain tissue for diagnostic use. We investigated a total of 37 samples including glioma (13), meningioma (7), metastatic tumors (9) and normal brain removed for nontumoral indications (8). Tissue was stained in 0.05 mg/mL aqueous solution of methylene blue (MB) for 2-5 minutes and multimodal confocal images were acquired using a custom-built microscope. After imaging, tissue was formalin fixed and paraffin embedded for standard neuropathologic evaluation. Thirteen pathologists provided diagnoses based on the multimodal confocal images. The investigated tumor types exhibited distinctive and complimentary characteristics in both the reflectance and fluorescence responses. Images showed distinct morphological features similar to standard histology. Pathologists were able to distinguish gliomas from normal brain tissue and nonglial brain tumors, and to render diagnoses from the images in a manner comparable to haematoxylin and eosin (H&E) slides. These results confirm the feasibility of multimodal confocal imaging for intravital intraoperative diagnosis.

Multimodal optical imaging for detecting breast cancer

The goal of the study was to evaluate wide-field and high-resolution multimodal optical imaging, including polarization, reflectance, and fluorescence for the intraoperative detection of breast cancer. Lumpectomy specimens were stained with 0.05 mg/ml aqueous solution of methylene blue (MB) and imaged. Wide-field reflectance images were acquired between 390 and 750 nm. Wide-field fluorescence images were excited at 640 nm and registered between 660 and 750 nm. High resolution confocal reflectance and fluorescence images were excited at 642 nm. Confocal fluorescence images were acquired between 670 nm and 710 nm. After imaging, the specimens were processed for hematoxylin and eosin (H&E) histopathology. Histological slides were compared with wide-field and high-resolution optical images to evaluate correlation of tumor boundaries and cellular morphology, respectively. Fluorescence polarization imaging identified the location, size, and shape of the tumor in all the cases investigated. Averaged fluorescence polarization values of tumor were higher as compared to normal tissue. Statistical analysis confirmed the significance of these differences. Fluorescence confocal imaging enabled cellular-level resolution. Evaluation and statistical analysis of MB fluorescence polarization values registered from single tumor and normal cells demonstrated higher fluorescence polarization from cancer. Wide-field high-resolution fluorescence and fluorescence polarization imaging shows promise for intraoperative delineation of breast cancers.

Mechanism of response of potential-sensitive dyes studied by time-resolved fluorescence

The mechanism of response of two potential-sensitive dyes, diOC(2)(5) (3,3'-diethyloxadicarbocyanine iodide) and oxonol V (bis-[3-phenyl-5-oxoisoxazol-4-yl]pentamethine oxonol), were studied by using steady-state and time-resolved fluorescence techniques. The lipid concentration dependence of the Deltapsi (membrane potential)-induced change in total fluorescence intensity was quite different for these two dyes. Time-resolved fluorescence measurements showed that the fluorescence decay of these dyes in membranes could be resolved into at least three exponentials. Deltapsi-induced changes in the levels of these three populations were also measured under a variety of conditions. In the case of diOC(2)(5) an inside negative Deltapsi increased the levels of the bound forms. This shows that diOC(2)(5) responds to Deltapsi mainly by an "on-off" mechanism whereby Deltapsi perturbs the membrane-water partition coefficient of the dye. The Deltapsi-induced changes approached zero when the dye was totally membrane bound. In contrast, the Deltapsi-induced response of oxonol V increased with increased membrane binding. An inside negative Deltapsi decreased the level of the bound form with a longer lifetime. This shows that the mechanism of response of oxonol V is a Deltapsi-induced shift in the equilibrium between bound forms of the dye.

Dye-enhanced multimodal confocal microscopy for noninvasive detection of skin cancers in mouse models

Skin cancer is the most common form of human cancer. Its early diagnosis and timely treatment is of paramount importance for dermatology and surgical oncology. In this study, we evaluate the use of reflectance and fluorescence confocal microscopy for detecting skin cancers in an in-vivo trial with B16F10 melanoma and SCCVII squamous cell carcinoma in mice. For the experiments, the mice are anesthetized, then the tumors are infiltrated with aqueous solution of methylene blue and imaged. Reflectance images are acquired at 658 nm. Fluorescence is excited at 658 nm and registered in the range between 690 and 710 nm. After imaging, the mice are sacrificed. The tumors are excised and processed for hematoxylin and eosin histopathology, which is compared to the optical images. The results of the study indicate that in-vivo reflectance images provide valuable information on vascularization of the tumor, whereas the fluorescence images mimic the structural features seen in histopathology. Simultaneous dye-enhanced reflectance and fluorescence confocal microscopy shows promise for the detection, demarcation, and noninvasive monitoring of skin cancer development.

Mitochondrial targeting of electron scavenging antioxidants: Regulation of selective oxidation vs random chain reactions

Effective regulation of highly compartmentalized production of reactive oxygen species and peroxidation reactions in mitochondria requires targeting of small molecule antioxidants and antioxidant enzymes into the organelles. This review describes recently developed approaches to mitochondrial targeting of small biologically active molecules based on: (i) preferential accumulation in mitochondria because of their hydrophobicity and positive charge (hydrophobic cations), (ii) binding with high affinity to an intra-mitochondrial constituent, and (iii) metabolic conversions by specific mitochondrial enzymes to reveal an active entity. In addition, targeted delivery of antioxidant enzymes via expression of leader sequences directing the proteins into mitochondria is considered. Examples of successful antioxidant and anti-apoptotic protection based on the ability of targeted cargoes to inhibit cytochrome c-catalyzed peroxidation of a mitochondria-specific phospholipid cardiolipin, in vitro and in vivo are presented. Particular emphasis is placed on the employment of triphenylphosphonium- and hemi-gramicidin S-moieties as two effective vehicles for mitochondrial delivery of antioxidants.

Porphyrin and galactosyl conjugated micelles for targeting photodynamic therapy

PURPOSE

To study the targeting and photodynamic therapy efficiency of porphyrin and galactosyl conjugated micelles based on amphiphilic copolymer galactosyl and mono-aminoporphyrin (APP) incoporated poly(2-aminoethyl methacrylate)-polycaprolactone (Gal-APP-PAEMA-PCL).

METHODS

Poly(2-aminoethyl methacrylate)-polycaprolactone (PAEMA-PCL) was synthesized by the combination of ring opening polymerization and reversible addition-fragmentation chain transfer (RAFT) polymerization, and then Gal-APP-PAEMA-PCL was obtained after conjugation of lactobionic acid and 5-(4-aminophenyl)-10,15,20-triphenylporphyrin (APP) to PAEMA-PCL. The chemical structures of the copolymers were characterized, and their biological properties were evaluated in human laryngeal carcinoma (HEp2) and human hepatocellular liver carcinoma (HepG2) cells.

RESULTS

Both APP-PAEMA-PCL and Gal-APP-PAEMA-PCL did not exhibit dark cytotoxicity to HEp2 cells and HepG2 cells. However, Gal-APP-PAEMA-PCL was taken up selectively by HepG2 cells and had the higher phototoxicity effect. Both polymers preferentially localized within cellular vesicles that correlated to the lysosomes.

CONCLUSIONS

The results indicated that porphyrin and galactosyl conjugated polymer micelles exhibited higher targeting and photodynamic therapy efficacy in HepG2 cells than in HEp2 cells.

Supported lipid bilayer templated J-aggregate growth: role of stabilizing cation-pi interactions and headgroup packing

Controlling the self-assembly of molecules into specific structural motifs has important implications for the design of materials with specific optical properties. We report here the results of a correlated confocal fluorescence-atomic force microscopy (AFM) study of pseudoisocyanine iodide (PIC) self-assembly on supported lipid bilayers. Through judicious selection of bilayer headgroup packing and chemistry, two types of PIC J-aggregates, distinguishable by their absorbance spectra, and both exhibiting strong resonant fluorescence and bathochromic shifts in absorbance relative to the monomer, were isolated. Remarkably, selective templating can be achieved using different zwitterionic headgroups, producing J-aggregates that display a larger bathochromic shift than their solution counterparts. Our correlated confocal-AFM studies coupled with FT-IR spectroscopy suggested that zwitterionic phospholipids mediate J-aggregate formation through specific cation-pi interactions between PIC and the lipid headgroups with the PIC molecules oriented largely perpendicular to the bilayer normal. The existence of the two isoforms further suggests that bilayer headgroup packing plays a key role in controlling interchromophore organization and subsequent aggregate nucleation and growth.

Targeting of cancer energy metabolism

The main purpose of this review is to update and analyze the effect of several antineoplastic drugs (adriamycin, apoptodilin, casiopeinas, cisplatin, clotrimazole, cyclophosphamide, ditercalinium, NSAIDs, tamoxifen, taxol, 6-mercaptopurine, and alpha-tocopheryl succinate) and energy metabolism inhibitors (2-DOG, gossypol, delocalized lipophilic cations, and uncouplers) on tumor development and progression. The possibility that these antineoplastic drugs currently used in in vitro cancer models, in chemo-therapy, or under study in phase I to III clinical trials induce tumor cellular death by altering also metabolite concentration (i.e., ATP), enzyme activities, and/or energy metabolism fluxes is assessed. It is proposed that the use of energy metabolic therapy, as an alternative or complementary strategy, might be a promising novel approach in the treatment of cancer.

Profiling of mitochondrial associated proteins from rat colon

Mitochondrial dysfunction, damage and mutations of mitochondrial proteins give rise to a range of ill understood patterns of disease. Although there is significant general knowledge of the proteins and the functional processes of the mitochondria, there is little knowledge of difference about how mitochondria respond and how they are regulated in different organs and tissues. Proteomic profiling of mitochondria and associated proteins involved in mitochondrial regulation and trafficking within cells and tissues has the potential to provide insights into mitochondrial dysfunction associated with many human diseases. The rat colon mitoproteome analysis presented here provides a useful tool to assist in identification and interpretation of mitochondrial dysfunction implicated in colon pathogenesis. 2DPAGE followed by LC/MS/MS was used to identify 430 proteins from mitochondrial enriched fractions prepared from rat colon, resulting in 195 different proteins or approximately 50% of the resolved proteins being identified as multiple protein expression forms. Proteins associated with the colon mitoproteome were involved in calcium binding, cell cycle, energy metabolism and electron transport chain, protein folding, protein synthesis and degradation, redox regulation, structural proteins, signalling and transporter and channel proteins. The mitochondrial associated proteins identified in this study of colon tissue complement and are compared with other recently published mitoproteome analyses from other organ tissues, and will assist in revealing potentially organ specific roles of the mitochondria and organ specific disease associated with mitochondrial dysfunction.

Multimodal confocal microscopy for diagnosing nonmelanoma skin cancers

BACKGROUND AND SIGNIFICANCE

The standard diagnostic procedure for skin cancers is invasive biopsy followed by histopathological evaluation. The biopsy may result in scarring and infection. A reliable way to noninvasively image suspicious lesions with high resolution and contrast would be valuable. In this study, the suitability of dye-enhanced multimodal confocal microscopy for the detection of nonmelanoma skin cancers was evaluated.

MATERIALS AND METHODS

For the experiments we used fresh tumor material stained using 0.2 mg/ml or 0.05 mg/ml aqueous solutions of methylene blue (MB) or toluidine blue (TB), respectively. Reflectance, fluorescence, and fluorescence polarization images of skin specimens stained with MB and TB were excited by 656 nm and 633 nm light, respectively. Fluorescence emission and anisotropy were registered between 690 nm and 710 nm. In addition, reference reflectance images at 830 nm were acquired. In total we imaged, analyzed, and compared to histology at least 10 samples of each tumor-type including nodular basal cell carcinoma (BCC), infiltrative basal cell carcinoma, and squamous cell carcinoma (SCC).

RESULTS AND CONCLUSION

The morphological features and appearance of skin structures in the fluorescence images correlate well with corresponding histology for all investigated tumor-types. Multi-spectral reflectance images provide information on the tissue spectral responses and are complimentary to the fluorescence images. The differences detected by fluorescence polarization in cancerous and normal structures may be used for cancerous tissue discrimination. Our results indicate the feasibility of using multimodal confocal microscopy as real-time tool for detecting skin pathology.

Tissue localization of photosensitizers and the mechanism of photodynamic tissue destruction

This paper outlines our present knowledge of photosensitizer tissue distribution, derived from preclinical animal studies, and relates it to the observed biological response to photodynamic therapy (PDT). Emphasis is placed on porphyrins (haematoporphyrin derivative (HpD), Photofrin II) and phthalocyanines (aluminum phthalocyanine sulphonate AlPcS). In mice, both groups of sensitizers show multiphasic plasma clearance kinetics with an initial rapid decline followed by further slow reduction. Residual amounts of Photofrin II are detectable 75 days after injection. Drug elimination occurs through urine and faeces, but faecal elimination predominates for Photofrin II. Circulating sensitizer greatly influences the mouse ear-swelling response, but not the foot response. Tumours and normal skin can be destroyed by vascular damage, if illumination occurs at times of maximal plasma sensitizer concentration, with no detectable sensitizer accumulation in tumour cells. Organ retention for both photosensitizer groups is similar and persistent. Organs rich in reticuloendothelial elements (liver, kidney, spleen) accumulate and retain the highest levels, skin and muscle the lowest, while normal brain tissue excludes sensitizer. The adrenal and pancreatic glands, as well as urinary bladder, also retain high amounts of Photofrin II. Tumour/skin ratios of 1 to 3:1 and 2 to 7:1 have been reported for porphyrins and sulphonated phthalocyanines respectively. Tissue destruction upon light exposure is not always correlated with photosensitizer levels, as is exemplified by liver and pancreas. Stromal sensitizer localization usually predominates in tumour and normal tissue, and often determines tumour response. Certain compounds, such as monosulphonated tetraphenylporphyrin and AlPcS, may favour parenchymal localization. The formed blood elements remain free of photosensitizer, while mast cells and macrophages accumulate especially large amounts and, upon illumination, release an array of vasoactive inflammatory and immune mediators.

Structural and physico-chemical determinants of the interactions of macrocyclic photosensitizers with cells

New therapies have been developed using reactive oxygen species produced by light-activation of photosensitizers (PS). Since the lifetime of these species is extremely short and their diffusion in space is limited, the photo-induced reactions primarily affect the cell organelles labeled by the PS. In addition to the development of molecules with the best optical and photosensitizing properties, considerable research has been done to understand the physico-chemical parameters governing their subcellular localization. In this review, we examine these parameters to establish the structure/efficacy relationships, which allow specific targeting of PS. We examine the effect of subcellular localization on the cellular response to photosensitization processes. We discuss the determinants of subcellular localization, including the hydrophobic/hydrophilic balance, the specific charge effects and the dynamics of PS' transfer through membranes. Specific targeting can also be achieved with molecular structures able to recognize cellular or intracellular receptors, and this is also dealt with in this paper.

Mitochondrial medicine: pharmacological targeting of mitochondria in disease

Mitochondria play a central role in cell life and death and are known to be important in a wide range of diseases including the cancer, diabetes, cardiovascular disease, and the age-related neurodegenerative diseases. The unique structural and functional characteristics of mitochondria enable the selective targeting of drugs designed to modulate the function of this organelle for therapeutic gain. This review discusses mitochondrial drug targeting strategies and a variety of novel mitochondrial drug targets including the electron transport chain, mitochondrial permeability transition, Bcl-2 family proteins and mitochondrial DNA. Mitochondrial drug-targeting strategies will open up avenues for manipulating mitochondrial functions and allow for selective protection or eradication of cells for therapeutic gain in a variety of diseases.

Singlet oxygen generation using iodinated squaraine and squaraine-rotaxane dyes

The goal of this study was to assess the ability of squaraine-rotaxanes to generate singlet oxygen for potential application in photodynamic therapy (PDT). Specifically, we compare the aggregation and photophysical properties of an iodinated squaraine dye and an iodinated squaraine-rotaxane. Even under strongly aggregating conditions, the absorption spectra of both remain relatively sharp. An X-ray crystal structure of the iodinated squaraine dye shows that it adopts perpendicular, end-to-face orientations in the solid state. Singlet oxygen generation efficiency was measured by trapping with 1,3-diphenylisobenzofuran. The triplet state of the rotaxane was characterized using laser flash photolysis. The results of this study suggest that heavily halogenated squaraine-rotaxanes have potential as singlet oxygen photosensitizers for PDT.

Glycosyl bis-porphyrin conjugates: Synthesis and potential application in PDT

Syntheses of new glycosylated neutral and cationic porphyrin dimers linked at the meso-position via a flexible hydrocarbon chain are described. A detailed 1H and 13C NMR study allows their complete structural elucidation. The UV-visible, fluorescence and MALDI mass spectra are also presented. Photocytotoxicities of these compounds against K562 leukaemia cell line are compared to those of Photofrin II.

Uses of photodynamic therapy in premalignant and malignant lesions of the gastrointestinal tract beyond the esophagus

Much has recently been written regarding the use of photodynamic therapy for the treatment of esophageal carcinoma and dysplastic Barrett's esophagus. This review, however, describes the clinical experience using photodynamic therapy with various photosensitizer agents for the treatment of diseases in other areas of the gut, especially the pancreaticobiliary tract where European studies have established the role of porfimer sodium photodynamic therapy in the management of patients with cholangiocarcinoma.

Targeted drug delivery to mammalian mitochondria in living cells

Mitochondrial dysfunction causes or contributes to a large number of human disorders including neuromuscular and neurodegenerative diseases, diabetes, ischaemia-reperfusion injury and cancer. Increasing efforts are being made towards mitochondria-directed pharmacological intervention, leading to the emergence of 'mitochondrial medicine' as a new field of biomedical research. The identification of new molecular mitochondrial drug targets in combination with the development of methods for selectively delivering biologically active molecules to the site of mitochondria will eventually launch new therapies for the treatment of mitochondria-related diseases, based either on the selective protection, repair or eradication of cells. This review discusses the need for the development of mitochondria-specific drug and DNA delivery systems, and evaluates the currently employed strategies for mitochondrial drug targeting, including some of their potential therapeutic applications.

Meso-substituted tetra-cationic porphyrins photosensitize the death of human fibrosarcoma cells via lysosomal targeting

In this paper we present a study on the intracellular localisation and the efficiency of cell photoinactivation of a series of derivatives of 5,10,15,20-tetrakis-(4-N-methylpyridyl)-porphine (C1), whose degree of lipophilicity was varied through replacement of one methyl group with an alkyl chain of various length. Human HT1080 fibrosarcoma cells exposed to the various C1 derivatives (0.25 microM) for 24 h and irradiated with increasing doses of red-light (0.45-27 J/cm2) were inactivated with different efficiencies. The efficiency of cell photoinactivation increased with the increasing length of the hydrocarbon tail and lipophilicity and correlated with the efficiency of the porphyrin accumulation into the cells. Despite the presence of positive charges, these porphyrins did localise rather selectively in lysosomes while mitochondrial localisation was not evident, as demonstrated by fluorescence microscopy studies. Studies on isolated mitochondria provided evidence that the porphyrin uptake and distribution in these organelles were not modulated by the transmembrane potential but were exclusively controlled by partitioning phenomena which might have prevented mitochondria localization in whole cells. Our findings demonstrated that these porphyrins entered the cells through the endocytotic pathway and were transported to lysosomes whose pH increased rapidly upon irradiation. Lysosomal damage did not cause any intracellular redistribution of the porphyrin and represented the primary event causing cell death, very likely via necrosis.