Preparation and Photodynamic Activities of Silicon(IV) Phthalocyanines Substituted with Permethylated β-Cyclodextrins

Amphiphilic Cationic Phthalocyanines for Photodynamic Therapy of Cancer

Effective interaction with biomembranes is essential for activity of photosensitizers; however, majority of them are highly charged symmetrical species. Amphiphilic cationic phthalocyanines differing in bulkiness of substitution on lipophilic part (-H, -SMe, -StBu) were therefore prepared. Compounds had high singlet oxygen production (ΦΔ =0.38-0.46, DMSO), good fluorescence emission (ΦF =0.21-0.26, DMSO), and log P values ranging -0.07-1.1 (1-octanol/PBS). Study of interaction with liposomes revealed that also bulky -StBu derivatives are able to enter biomembranes. Detail in vitro studies (toxicity, subcellular localization, type of cell death, and morphology) were performed. Compounds were characterized by excellent EC50 values in range of dozens of nM (HeLa, EA.hy926, MCF-7, HCT116), which were dependent on drug-light interval and reached plateau after 4 h on HeLa cells. Well-balanced lipophilicity with ability to interact with biomembranes rank these derivatives among perspective photosensitizers, even for vascular-targeted PDT (VTP) since they kill EA.hy926 without any preincubation time.

Covalent RGD-graphene-phthalocyanine nanocomposite for fluorescence imaging-guided dual active/passive tumor-targeted combinatorial phototherapy

Poor tumor selectivity, low stability and quenched fluorescence are the main challenges to be overcome for nanomedicine, and are mainly caused by the dissociation of the nanostructure and aggregation of chromophores in the biological environment. Herein, covalently connected nanoparticles RGD-graphene-phthalocyanine (RGD-GO-SiPc) were constructed based on RGD peptide, silicon phthalocyanine (SiPc) and graphene oxide (GO) via a conjugation reaction for fluorescence imaging-guided cancer-targeted combinatorial phototherapy. The prepared RGD-GO-SiPc exhibited supreme biological stability, high-contrast fluorescence imaging, significantly enhanced NIR absorption, high photothermal conversion efficiency (25.6%), greatly improved cancer-targeting capability, and synergistic photodynamic (PDT) and photothermal therapy (PTT) efficacy along with low toxicity. Both in vitro and in vivo biological studies showed that RGD-GO-SiPc is a kind of promising multifunctional nanomedicine for fluorescence imaging-guided combined photothermal and photodynamic therapy with dual active/passive tumor-targeting properties.

Recent Strategies to Develop Innovative Photosensitizers for Enhanced Photodynamic Therapy

This review presents a robust strategy to design photosensitizers (PSs) for various species. Photodynamic therapy (PDT) is a photochemical-based treatment approach that involves the use of light combined with a light-activated chemical, referred to as a PS. Attractively, PDT is one of the alternatives to conventional cancer treatment due to its noninvasive nature, high cure rates, and low side effects. PSs play an important factor in photoinduced reactive oxygen species (ROS) generation. Although the concept of photosensitizer-based photodynamic therapy has been widely adopted for clinical trials and bioimaging, until now, to our surprise, there has been no relevant review article on rational designs of organic PSs for PDT. Furthermore, most of published review articles in PDT focused on nanomaterials and nanotechnology based on traditional PSs. Therefore, this review aimed at reporting recent strategies to develop innovative organic photosensitizers for enhanced photodynamic therapy, with each example described in detail instead of providing only a general overview, as is typically done in previous reviews of PDT, to provide intuitive, vivid, and specific insights to the readers.

β-Cyclodextrin-conjugated phthalocyanines as water-soluble and recyclable sensitisers for photocatalytic applications

Two zinc(ii) phthalocyanines substituted with two and four permethylated β-cyclodextrin moieties at the α positions have been synthesised and immobilised on the surface of adamantane-modified silica nanoparticles through host-guest interactions. These molecular and supramolecular systems can catalyse the photooxygenation of 1-naphthol and 2-furoic acid in organic and aqueous media with high conversion efficiency and reaction yield, and photodegradation of 2-chlorophenol in water. Having a higher photostability and recyclability, the supramolecular nanosystems are particularly promising for these photocatalytic applications.

Antimicrobial Photodynamic Therapy Combined With Antibiotic in the Treatment of Rats With Third-Degree Burns

Cationic porphyrin conjugate, protoporphyrin IX-methyl ethylenediamine derivative (PPIX-MED) has a potent photosensitive antibacterial effect on clinically isolated bacteria, including methicillin-resistant Staphylococcus aureus, (MRSA), Escherichia coli, and Pseudomonas aeruginosa. This study investigated (i) the PPIX-MED-mediated antimicrobial photodynamic effect on these three species in vitro and (ii) the effect of antimicrobial photodynamic therapy (aPDT) combined with the use of an antibiotic on the healing in vivo of third-degree burns of rats with the wounds infected by these bacterial species. PPIX-MED exerted a potent inhibitory effect on the growth of the three bacterial species by producing reactive oxygen species when photoactivated. PPIX-MED-mediated antimicrobial photodynamic therapy (PPIX-MED-aPDT) had high bacterial photoinactivation ability in vitro, with a minimum inhibitory concentration of 15.6 μM PPIX-MED against each of the three types of bacteria and minimum bactericidal concentrations of 31.25 μM against MRSA and E. coli and 62.5 μM against P. aeruginosa. In rats with third-degree burns infected by a mixture of these bacteria, the bactericidal efficiency of PPIX-MED–aPDT-combined-with-antibiotic treatment was higher than that of antibiotic or aPDT treatment alone. This was confirmed by analysis of viable bacterial counts in wound tissue and blood. Enzyme-linked immunosorbent assay revealed that aPDT-combined-with-antibiotic treatment resulted in an obvious reduction in tumor necrosis factor-alpha and interleukin-6 levels compared with the no-treatment control group and the other treatment groups. Immunohistochemistry revealed that the expression of basic fibroblast growth factor and CD31 (a marker of neovascularization), expressed in burn wound tissue was higher in the aPDT-combined-with-antibiotic treatment group than in the other groups. PPIX-MED–aPDT has a promising bactericidal effect both in vitro and in vivo, and PPIX-MED–aPDT-combined-with-antibiotic treatment enhanced the healing of infected third-degree burns in rats.

Silicon phthalocyanines: synthesis and resurgent applications

Their unique axial bonds and NIR optical properties have made silicon phthalocyanines (SiPcs) valuable compounds. Herein, we present key synthetic strategies and emerging applications of SiPcs over the past decade.

Photodynamic antimicrobial chemotherapy in mice with Pseudomonas aeruginosa-infected wounds

This study examined the antibacterial effect of protoporphyrin IX–ethylenediamine derivative (PPIX-ED)–mediated photodynamic antimicrobial chemotherapy (PPIX-ED-PACT) against Pseudomonas aeruginosa in vitro and in vivo. PPIX-ED potently inhibited the growth of Pseudomonas aeruginosa by inducing reactive oxygen species production via photoactivation. Atomic force microscopy revealed that PPIX-ED-PACT induced the leakage of bacterial content by degrading the bacterial membrane and wall. As revealed using acridine orange/ethidium bromide staining, PPIX-ED-PACT altered the permeability of the bacterial membrane. In addition, the antibacterial effect of PPIX-ED-PACT was demonstrated in an in vivo model of P. aeruginosa-infected wounds. PPIX-ED (100 μM) decreased the number of P. aeruginosa colony-forming units by 4.2 log₁₀. Moreover, histological analysis illustrated that the wound healing rate was 98% on day 14 after treatment, which was 10% higher than that in the control group. According to the present findings, PPIX-ED-PACT can effectively inhibit the growth of P. aeruginosa in vitro and in vivo.

Dually directional glycosylated phthalocyanines as extracellular red-emitting fluorescent probes

The development of new non-aggregated phthalocyanines bearing multivalent saccharide moieties on their macrocyclic rims is of great interest. Many characteristics, including water-solubility, non-toxicity and others, can be feasibly obtained by these amphiphiles which can be considered as a key solution for demonstrating highly efficient photoactive materials in water. Herein, a family of five newly prepared dually directional Zn(ii) containing phthalocyanines (PcG1-4) and azaphthalocyanine (AzaPcG1) glycoconjugates is described. The unique spatial arrangement of the glucoside units based on peripherally hexadeca-(PcG1) and nonperipherally octa-(PcG4) macrocycles provides a fully monomeric behaviour along with a high fluorescence (Φ_F∼ 0.21) in aqueous solution. These amphiphiles were characterized by low toxicity, and an extremely low cellular uptake was obtained due to the highly polar nature of the glucoside substituents. Accordingly, their potential as suitable photoactive chromophores for red-emitting extracellular fluorescent probes has been confirmed upon the evaluation of paracellular transport using a layer of MDCKII cells with the permeability coefficient fully comparable with an established evaluator of the integrity of the monolayer.

Photo-physicochemical properties of water-soluble non-aggregated indium(III) phthalocyanines

Phthalocyanines have interesting optoelectronic properties but typically suffer from aggregation in aqueous solution, which can limit their applicability, especially in photodynamic therapy. In this study, indium(III) phthalocyanine peripherally substituted with eight triazolyl-containing phenoxy groups (InOAc) and its water-soluble analogue (Q-InOAc) were synthesised and structurally characterised. Heavy metal effects, exerted by the central indium ion, on the photosensitising and photophysical properties (singlet oxygen quantum yield, singlet state lifetime and quantum yield, and triplet state lifetime) were investigated in both DMF and D₂O. Highly efficient generation of the triplet excited state (T1), induced by the incorporation of a large atom, enhanced singlet oxygen formation, as revealed by both chemical and physical methods. Correspondingly, the singlet oxygen quantum yield (Φ_Δ) of Q-InOAc was 0.603 in DMF and 0.433 in D₂O. These values are higher than those previously reported for the corresponding metal-free, Mg-based, and Zn-based water-soluble phthalocyanines (HH, Mg, and Zn). Consequently, Q-InOAc is expected to be an excellent photosensitiser for photodynamic therapy.

A Hybrid Nanomaterial Based on Single Walled Carbon Nanotubes Cross-Linked via Axially Substituted Silicon (IV) Phthalocyanine for Chemiresistive Sensors

In this work, the novel hybrid nanomaterial SWCNT/SiPc made of single walled carbon nanotubes (SWCNT) cross-linked via axially substituted silicon (IV) phthalocyanine (SiPc) was studied as the active layer of chemiresistive layers for the detection of ammonia and hydrogen. SWCNT/SiPc is the first example of a carbon-based nanomaterial in which an axially substituted phthalocyanine derivative is used as a linker. The prepared hybrid material was characterized by spectroscopic methods, thermogravimetry, scanning and transmission electron microscopies. The layers of the prepared hybrid were tested as sensors toward ammonia and hydrogen by a chemiresistive method at different temperatures and relative humidity as well as in the presence of interfering gases like carbon dioxide, hydrogen sulfide and volatile organic vapors. The hybrid layers exhibited the completely reversible sensor response to both gases at room temperature; the recovery time was 100-200 s for NH3 and 50-120 s in the case of H2 depending on the gas concentrations. At the relative humidity (RH) of 20%, the sensor response was almost the same as that measured at RH 5%, whereas the further increase of RH led to its 2-3 fold decrease. It was demonstrated that the SWCNT/SiPc layers can be successfully used for the detection of both NH3 and H2 in the presence of CO2. On the contrary, H2S was found to be an interfering gas for the NH3 detection.

Self-assembly of azaphthalocyanine–oligodeoxynucleotide conjugates into J-dimers: towards biomolecular logic gates

Unique spatial self-assembly of azaphthalocyanine–oligonucleotide–fluorescein conjugates can be selectively dissociated by a complementary sequence or coordinating solvent and used for the development of biomolecular logic gates.

Porphyrinoid-Cyclodextrin Assemblies in Biomedical Research: An Update

Porphyrinoids, well-known cofactors in fundamental processes of life, have stimulated interest as synthetic models of natural systems and integral components of photodynamic therapy, but their utilization is compromised by self-aggregation in aqueous media. The capacity of cyclodextrins to include hydrophobic molecules in their cavity provides porphyrinoids with a protective environment against oxidation and the ability to disperse efficiently in biological fluids. Moreover, engineered cyclodextrin-porphyrinoid assemblies enhance the photodynamic abilities of porphyrinoids, can carry chemotherapeutics for synergistic modalities, and can be enriched with functions including cell recognition, tissue penetration, and imaging. This Perspective includes synthetic porphyrinoid-cyclodextrin models of proteins participating in fundamental processes, such as enzymatic catalysis, respiration, and electron transfer. In addition, since porphyrinoid-cyclodextrin systems comprise third generation photosensitizers, recent developments for their utilization in photomedicine, that is, multimodal therapy for cancer (e.g., PDT, PTT) and antimicrobial treatment, and eventually in biocompatible therapeutic or diagnostic platforms for next-generation nanomedicine and theranostics are discussed.

Biotinylated-cationic zinc(II) phthalocyanine towards photodynamic therapy

Targeting biotin receptors in cancer cells can improve specifying of photosensitizers (PSs) for cancer treatment by photodynamic therapy (PDT) applications. Consequently, there has been extensive research focusing mainly on the design of PSs with optimized pharmaceutical properties and better targeting toward cancer cells. Herein a tailored mono-biotinylated zinc(II) phthalocyanine (Pc-1) substituted with six phenoxy-bis(triazolyl) substituents has been synthesized. This Pc-1 has been further modified to its cationic version (Pc-2) through quaternizing of the triazole moiety to gain water solubility. Both non-ionic zinc(II) phthalocyanine (Pc-1) and its cationic derivative (Pc-2) were characterized by standard spectroscopic techniques, namely; FT-IR, 1H and [Formula: see text]C NMR, UV-Vis and MALDI-TOF, and by elemental analysis. The photophysical and photochemical properties were evaluated in DMSO for the non-ionic Pc-1 and in both DMSO and water for the cationic Pc-2.

Use of Cyclodextrins in Anticancer Photodynamic Therapy Treatment

Photodynamic therapy (PDT) is mainly used to destroy cancerous cells; it combines the action of three components: a photoactivatable molecule or photosensitizer (PS), the light of an appropriate wavelength, and naturally occurring molecular oxygen. After light excitation of the PS, the excited PS then reacts with molecular oxygen to produce reactive oxygen species (ROS), leading to cellular damage. One of the drawbacks of PSs is their lack of solubility in water and body tissue fluids, thereby causing low bioavailability, drug-delivery efficiency, therapeutic efficacy, and ROS production. To improve the water-solubility and/or drug delivery of PSs, using cyclodextrins (CDs) is an interesting strategy. This review describes the in vitro or/and in vivo use of natural and derived CDs to improve antitumoral PDT efficiency in aqueous media. To achieve these goals, three types of binding modes of PSs with CDs are developed: non-covalent CD⁻PS inclusion complexes, covalent CD⁻PS conjugates, and CD⁻PS nanoassemblies. This review is divided into three parts: (1) non-covalent CD-PS inclusion complexes, covalent CD⁻PS conjugates, and CD⁻PS nanoassemblies, (2) incorporating CD⁻PS systems into hybrid nanoparticles (NPs) using up-converting or other types of NPs, and (3) CDs with fullerenes as PSs.

Conjugate of biotin with silicon(IV) phthalocyanine for tumor-targeting photodynamic therapy

In order to improve the efficacy of photodynamic therapy (PDT), biotin was axially conjugated with silicon(IV) phthalocyanine (SiPc) skeleton to develop a new tumor-targeting photosensitizer SiPc-biotin. The target compound SiPc-biotin showed much higher binding affinity toward BR-positive (biotin receptor overexpressed) HeLa human cervical carcinoma cells than its precursor SiPc-pip. However, when the biotin receptors of HeLa cells were blocked by free biotin, >50% uptake of SiPc-biotin was suppressed, demonstrating that SiPc-biotin could selectively accumulate in BR-positive cancer cells via the BR-mediated internalization. The confocal fluorescence images further confirmed the target binding ability of SiPc-biotin. As a consequence of specificity of SiPc-biotin toward BR-positive HeLa cells, the photodynamic effect was also largely dependent on the BR expression level of HeLa cells. The photodynamic activities of SiPc-biotin against HeLa cells were dramatically reduced when the biotin receptors were blocked by the free biotin (IC₅₀: 0.18μM vs. 0.46μM). It is concluded that SiPc-biotin can selectively damage BR-positive cancer cells under irradiation. Furthermore, the dark toxicity of SiPc-biotin toward human normal liver cell lines LO2 was much lower than that of its precursor SiPc-pip. The targeting photodynamic activity and low dark toxicity suggest that SiPc-biotin is a promising photosensitizer for tumor-targeting photodynamic therapy.

Phthalocyanines and Tetrapyrazinoporphyrazines with Two Cationic Donuts: High Photodynamic Activity as a Result of Rigid Spatial Arrangement of Peripheral Substituents

High photodynamic activity was observed for hexadeca-cationic zinc, magnesium, and metal-free phthalocyanines (Pcs) and tetrapyrazinoporphyrazines with EC₅₀ values as low as 5 nM (MCF-7 cells) for the best compound; this activity was several times better than that of clinically established photosensitizers verteporfin, temoporfin, S₃AlOHPc, or protoporphyrin IX. This lead compound was characterized by low dark toxicity (TC₅₀ = 369 μM), high efficiency against other cell lines (HCT 116 and HeLa), and possible activation by light above 680 nm. The excellent photodynamic activity resulted from the rigid spatial arrangement of the quaternized triazole moieties above and below the Pc core, as confirmed by X-ray crystallography. The triazole moieties thus formed two "cationic donuts" that protected the hydrophobic core against aggregation in water. The lysosomes were found to be the site of subcellular localization and were consequently the primary targets of photodynamic injury, resulting in predominantly necrotic cell death.

Tetra(3,4-pyrido)porphyrazines Caught in the Cationic Cage: Toward Nanomolar Active Photosensitizers

Investigation of a series of tetra(3,4-pyrido)porphyrazines (TPyPzs) substituted with hydrophilic substituents revealed important structure-activity relationships for their use in photodynamic therapy (PDT). Among them, a cationic TPyPz derivative with total of 12 cationic charges above, below and in the plane of the core featured a unique spatial arrangement that caught the hydrophobic core in a cage, thereby protecting it fully from aggregation in water. This derivative exhibited exceptionally effective photodynamic activity on a number of tumor cell lines (HeLa, SK-MEL-28, A549, MCF-7) with effective concentrations (EC₅₀) typically below 5 nM, at least an order of magnitude better than the EC₅₀ values obtained for the clinically approved photosensitizers verteporfin, temoporfin, protoporphyrin IX, and trisulfonated hydroxyaluminum phthalocyanine. Its very low dark toxicity (TC₅₀ > 400 μM) and high ability to induce photodamage to endothelial cells (EA.hy926) without preincubation suggest the high potential of this cationic TPyPz derivative in vascular-targeted PDT.

Anionic hexadeca-carboxylate tetrapyrazinoporphyrazine: synthesis and in vitro photodynamic studies of a water-soluble, non-aggregating photosensitizer

Photodynamic activity of hexadeca-carboxylate tetrapyrazinoporphyrazine is largely influenced by intracellular pH and its interaction with serum proteins.

Dendrimer-encapsulated naphthalocyanine as a single agent-based theranostic nanoplatform for near-infrared fluorescence imaging and combinatorial anticancer phototherapy

Multifunctional theranostic platforms capable of concurrent near-infrared (NIR) fluorescence imaging and phototherapies are strongly desired for cancer diagnosis and treatment. However, the integration of separate imaging and therapeutic components into nanocarriers results in complex theranostic systems with limited translational potential. A single agent-based theranostic nanoplatform, therefore, was developed for concurrent NIR fluorescence imaging and combinatorial phototherapy with dual photodynamic (PDT) and photothermal (PTT) therapeutic mechanisms. The transformation of a substituted silicon naphthalocyanine (SiNc) into a biocompatible nanoplatform (SiNc-NP) was achieved by SiNc encapsulation into the hydrophobic interior of a generation 5 polypropylenimine dendrimer following surface modification with polyethylene glycol. Encapsulation provides aqueous solubility to SiNc and preserves its NIR fluorescence, PDT and PTT properties. Moreover, an impressive photostability in the dendrimer-encapsulated SiNc has been detected. Under NIR irradiation (785 nm, 1.3 W cm(-2)), SiNc-NP manifested robust heat generation capability (ΔT = 40 °C) and efficiently produced reactive oxygen species essential for PTT and PDT, respectively, without releasing SiNc from the nanopaltform. By varying the laser power density from 0.3 W cm(-2) to 1.3 W cm(-2) the therapeutic mechanism of SiNc-NP could be switched from PDT to combinatorial PDT-PTT treatment. In vitro and in vivo studies confirmed that phototherapy mediated by SiNc can efficiently destroy chemotherapy resistant ovarian cancer cells. Remarkably, solid tumors treated with a single dose of SiNc-NP combined with NIR irradiation were completely eradicated without cancer recurrence. Finally, the efficiency of SiNc-NP as an NIR imaging agent was confirmed by recording the strong fluorescence signal in the tumor, which was not photobleached during the phototherapeutic procedure.

Non-aggregated axially disubstituted silicon phthalocyanines bearing electropolymerizable ligands and their aggregation, electropolymerizaton and thermal properties

The electropolymerization of a specially synthesised series of silicon(iv) phthalocyanines was studied for the first time by various electrochemical measurements.

A dual activatable photosensitizer toward targeted photodynamic therapy

An unsymmetrical bisferrocenyl silicon(IV) phthalocyanine has been prepared in which the disulfide and hydrazone linkers can be cleaved by dithiothreitol and acid, respectively. The separation of the ferrocenyl quenchers and the phthalocyanine core greatly enhances the fluorescence emission, singlet oxygen production, intracellular fluorescence intensity, and in vitro photocytotoxicity. The results have been compared with those for the two symmetrical analogues which contain either the disulfide or hydrazone linker and therefore can only be activated by one of these stimuli. For the dual activatable agent, the greatest enhancement can be attained under a slightly acidic environment (pH = 4.5-6.8) and in the presence of dithiothreitol (in millimolar range), which can roughly mimic the acidic and reducing environment of tumor tissues. This compound can also be activated in tumor-bearing nude mice. It exhibits an increase in fluorescence intensity in the tumor over the first 10 h after intratumoral injection and can effectively inhibit the growth of tumor upon illumination.

Amphiphilic phthalocyanine–cyclodextrin conjugates for cancer photodynamic therapy

Three phthalocyanines (Pcs) conjugated with α-, β- and γ-cyclodextrins (CDs) were prepared and their application as photosensitizer (PS) agents was evaluated.

Selective photodynamic therapy induced by preirradiation of galactopyranosyl Zn(II) phthalocyanines with UV and red lights

The challenging task in the photodynamic therapy is the optimization of the procedure in a way to reach maximal selectivity of the phototoxic effect to tumor vs. non-neoplastic cells. The present study explores the impact of the light exposure with harmless UV 365 nm and low intensity visible red 637 nm light during incubation period on the uptake, primary localization, re-localization and photocytotoxic effect of tetra-galactopyranosyl substituted Zn ( II ) phthalocyanines. The studies were carried out on cancer cells (MDA-MB-231) and on non-tumorigenic cells (Balb/c 3T3, clone 31). The experimentals suggested that in addition to the favorable chemical structure of the applied amphiphilic protected galactose Zn ( II ) phthalocyanines, the pretreatment with UV 365 nm and visible red 637 nm light applied prior therapeutic light, lead to selective phototoxic effects on tumor cells.

Enhanced photodynamic efficiency of an aptamer-guided fullerene photosensitizer toward tumor cells

Fullerene-based photosensitizers exhibit great potential in photodynamic therapy (PDT). Based on the high photodynamic efficacy of trimalonic acid-modified C70 fullerene (TF70), we constructed an aptamer-guided TF70 photosensitizer and investigated its photodynamic effect. Conjugation of the novel aptamer (named R13) could effectively enhance the PDT efficiency of TF70 against A549 lung cancer cells in the presence of serum. The lysosomal location of the TF70-R13 conjugate inside cells facilitates the production of intracellular reactive oxygen species (ROS), which can efficiently kill cells, under light irradiation. The enhanced photodynamic efficiency, along with its good biocompatibility in the dark, makes TF70-R13 a highly promising photosensitizer for tumor-specific PDT.

Cellular uptake of octaarginine-conjugated tetraarylporphyrin included by per-O-methylated β-cyclodextrin

This paper describes the synthesis, structural characterization and cellular uptake of a supramolecular 1 : 2 inclusion complex of meso-tetraphenylporphyrin having an octaarginine peptide chain (R8-TPP) and heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin (TMe-β-CD). R8-TPP was synthesized by 2 approaches: (1) on-resin conjugation of the N-terminal of octaarginine with 5-(4-carboxyphenyl)-10,15,20-triphenylporphyrin, followed by cleavage from the resin, and (2) Michael addition reaction between 5-[4-(3-maleimidopropylamido)phenyl]-10,15,20-triphenylporphyrin and cysteine-octaarginine peptide (Cys-Arg8). The R8-TPP obtained from both the approaches formed stable inclusion complexes with TMe-β-CD by which non-substituted phenyl groups at the 10- and 20-positions were included to form trans-type 1 : 2 inclusion complexes. The complexation prevented the self-aggregation of R8-TPP, which resulted in the solubilisation of R8-TPP in aqueous media. A cellular uptake study using HeLa cells showed that R8-TPP complexed with TMe-β-CD in a serum-free medium was efficiently taken up by the cells and uniformly dispersed in the cytosol. In the serum-containing medium, the R8-TPP-TMe-β-CD complex dissociated, and the serum protein bound R8-TPP. The R8-TPP-protein complex was localized in the endosomes of the cells. The cytosol-dispersed R8-TPP showed a higher photo-induced cytotoxicity than its endosome-trapped counterpart.

Triple-functional core-shell structured upconversion luminescent nanoparticles covalently grafted with photosensitizer for luminescent, magnetic resonance imaging and photodynamic therapy in vitro

Upconversion luminescent nanoparticles (UCNPs) have been widely used in many biochemical fields, due to their characteristic large anti-Stokes shifts, narrow emission bands, deep tissue penetration and minimal background interference. UCNPs-derived multifunctional materials that integrate the merits of UCNPs and other functional entities have also attracted extensive attention. Here in this paper we present a core-shell structured nanomaterial, namely, NaGdF(4):Yb,Er@CaF(2)@SiO(2)-PS, which is multifunctional in the fields of photodynamic therapy (PDT), magnetic resonance imaging (MRI) and fluorescence/luminescence imaging. The NaGdF(4):Yb,Er@CaF(2) nanophosphors (10 nm in diameter) were prepared via sequential thermolysis, and mesoporous silica was coated as shell layer, in which photosensitizer (PS, hematoporphyrin and silicon phthalocyanine dihydroxide) was covalently grafted. The silica shell improved the dispersibility of hydrophobic PS molecules in aqueous environments, and the covalent linkage stably anchored the PS molecules in the silica shell. Under excitation at 980 nm, the as-fabricated nanomaterial gave luminescence bands at 550 nm and 660 nm. One luminescent peak could be used for fluorescence imaging and the other was suitable for the absorption of PS to generate singlet oxygen for killing cancer cells. The PDT performance was investigated using a singlet oxygen indicator, and was investigated in vitro in HeLa cells using a fluorescent probe. Meanwhile, the nanomaterial displayed low dark cytotoxicity and near-infrared (NIR) image in HeLa cells. Further, benefiting from the paramagnetic Gd(3+) ions in the core, the nanomaterial could be used as a contrast agent for magnetic resonance imaging (MRI). Compared with the clinical commercial contrast agent Gd-DTPA, the as-fabricated nanomaterial showed a comparable longitudinal relaxivities value (r(1)) and similar imaging effect.

Effect of intramolecular charge transfer on fluorescence and singlet oxygen production of phthalocyanine analogues

Intramolecular charge transfer (ICT) was studied on a series of magnesium, metal-free and zinc complexes of unsymmetrical tetrapyrazinoporphyrazines and tribenzopyrazinoporphyrazines bearing two dialkylamino substituents (donors) and six alkylsulfanyl or aryloxy substituents (non-donors). The dialkylamino substituents were responsible for ICT that deactivated excited states and led to considerable decrease of fluorescence and singlet oxygen quantum yields. Photophysical and photochemical properties were compared to corresponding macrocycles that do not bear any donor centers. The data showed high feasibility of ICT in the tetrapyrazinoporphyrazine macrocycle and significantly lower efficiency of this deactivation process in the tribenzopyrazinoporphyrazine type molecules. Considerable effect of non-donor peripheral substituents on ICT was also described. The results imply that tetrapyrazinoporphyrazines may be more suitable for development of new molecules investigated in applications based on ICT.

Photophysics and photochemistry of octaglucosylated zinc phthalocyanine derivatives

The ground state electronic absorption spectra, photophysics and photochemistry of amphiphilic octaglucosylated zinc phthalocyanines containing oxygen or sulfur bridges are presented. Triplet quantum yield values for the two dyes (in DMF and DMSO) vary between 0.71 and 0.84, while singlet quantum yield values lie between 0.63 and 0.75. Fluorescence lifetimes were determined experimentally by time correlated single photon counting and semi-empirically by fluorescence quenching techniques; and values from both methods were within the same range. Kinetic data were obtained for the quenching of the triplet state of the phthalocyanines by ground state molecular oxygen; the bimolecular collisional quenching rate constant range between 2.35 × 108 and 1.13 × 109 M-1.s-1. These values suggest that triplet states of the dyes are effectively quenched by ground molecular oxygen.

Spectral, photophysical and photochemical properties of tetra- and octaglycosylated zinc phthalocyanines

Photophysical and photochemical properties of a series of tetra- and octaglycosylated zinc phthalocyanines (ZnPcs) substituted with glucose and galactose moieties have been reported. Spectral properties of these phthalocyanines are compared in DMSO. Absorption spectra of the non-peripherally tetra-substituted ZnPcs 2 showed a significant red shift in their Q-band maxima as compared to the peripherally substituted analog 1. All the complexes gave high triplet quantum yields ranging from 0.68 to 0.88, whereas triplet lifetimes were in the range of 100-430 μs in argon-saturated solutions. The octagalactosylated ZnPc 3b showed the highest triplet quantum yield and singlet oxygen quantum yield of 0.88 and 0.69, respectively. The fluorescence quantum yields and lifetimes of all the compounds under investigation were within the range of zinc phthalocyanine complexes.