Encapsulation Of Photosensitizers Research Articles

Specifically Targeting Capture and Photoinactivation of Viruses through Phosphatidylcholine-Ganglioside Vesicles with Photosensitizer.

Herein, we performed a simple virus capture and photoinactivation procedure using visible light on phosphatidylcholine vesicles. l-α-Phosphatidylcholine vesicles were enriched by viral receptors, GT1b gangliosides, and the nonpolar photosensitizer 5,10,15,20-tetraphenylporphyrin. These vesicles absorb in the blue region of visible light with a high quantum yield of antiviral singlet oxygen, O2 (1Δg). Through the successful incorporation of gangliosides into the structure of vesicles and the encapsulation of photosensitizers in their photoactive and monomeric state, the photogeneration of O2(1Δg) was achieved with high efficiency on demand; this process was triggered by light, and specifically targeting/inactivating viruses were captured on ganglioside receptors due to the short lifetime (3.3 μs) and diffusion pathway (approximately 100 nm) of O2(1Δg). Time-resolved and steady-state luminescence as well as absorption spectroscopy were used to monitor the photoactivity of the photosensitizer and the photogeneration of O2(1Δg) on the surface of the vesicles. The capture of model mouse polyomavirus and its inactivation were achieved using immunofluorescence methods, and loss of infectivity toward mouse fibroblast 3T6 cells was detected.

Compartmentalization Accelerates Photosensitized NADH to NAD+ Conversion

AbstractConfinement of reaction spaces was achieved in a biomimetic manner by using liposome vesicles that are based on phospholipid bilayer membranes, similar to cellular compartments. Encapsulation of photosensitizer (PS) and substrate within the inner aqueous compartment of liposomes accelerated the photosensitized model reaction of nicotinamide adenine dinucleotide (NADH) conversion to its oxidized form (NAD+) by one order of magnitude compared to classical homogeneous reaction conditions. Furthermore, it was found that the reaction proceeds around 40 % faster when the photosensitizer is dissolved in the inner aqueous compartment instead of being embedded within the phospholipid bilayer which is attributed to the diffusion behavior of singlet oxygen which acts as oxidant in this reaction. These experimental findings will allow for reaction and molecular systems design for photochemical and catalytic conversions and will be relevant in the context of creating artificial cellular compartments such as fully artificial chloroplasts.

Encapsulation of photosensitizer in niosomes for promotion of antitumor and antimicrobial photodynamic therapy

Photodynamic therapy (PDT) combines light with photosensitizers (PS) to produce reactive oxygen species (ROS) that can eliminate pathogenic microorganisms and tumor cells. Niosomes (NSs) are efficient nanocarriers and able to disperse insoluble drugs in water. Zinc phthalocyanine (ZnPc) is an excellent PS with water solubility problem that can be resolved by encapsulation in NSs. It is possible to apply PDT without inducing resistance to microorganisms or cells, since ROS interact in different cellular structures, such as proteins, lipid membranes and nucleic acids, avoiding the activation of resistance mechanisms. This work aims to develop NSs containing ZnPc to promote PDT against skin infections caused by pathogenic microorganisms and melanoma, the most severe type of skin cancer. Experimental planning was used to optimize the preparation of NSs with an average size of 233 ± 5.6 nm with PdI of 0.22 ± 0.07 nm and charge of −36.73 ± 0.65 mV, showing spherical and regular shape. Cationic NSs were also produced by surface modification of vesicles with chitosan and exhibited superior photobiological activity. NSs (anionic and cationic) containing ZnPc showed low dark cytotoxicity and intense photobiological activity after light irradiation. Antitumor and antimicrobial photobiological activities of NSs were tested on melanoma cells, methicillin-resistant Staphylococcus aureus (MRSA) and Candida albicans. The system showed excellent production of ROS in cell culture and apoptosis can be probably the main mechanism of cell death. The results show that NSs containing PS are versatile and can eliminate pathogenic microorganisms, such as bacteria and fungi of clinical interest and tumor cells.

Oxidation-sensitive polymeric nanocarrier-mediated cascade PDT chemotherapy for synergistic cancer therapy and potentiated checkpoint blockade immunotherapy

Photodynamic therapy (PDT) is a promising therapeutic strategy for the clinical treatment of laryngeal cancer, and nanocarriers could be easily combined PDT with conventional chemotherapy for enhanced therapeutic outcomes. However, the encapsulation of photosensitizers (PS) and chemotherapy drugs into conventional nanocarriers achieves only a simple combination without synergistic effects. Herein, we explored an oxidation-sensitive polyphosphoester (PPE)-based nanocarrier to co-encapsulate chlorin e6 (Ce6) and docetaxel (Dtxl) for synergistic laryngeal cancer therapy. During the PDT process, the produced ROS not only induced cell apoptosis but also triggered the release of Dtxl through the hydrophobic to hydrophilic transition of the PPE core, resulting in a cascade PDT/chemotherapy to elicit a synergistic anticancer effect for the complete suppression of laryngeal cancer growth. Moreover, this oxidation-sensitive nanocarrier-mediated cascade PDT/chemotherapy can also induce an effective antitumor immune response via the immunogenic cell death effect (ICD) and potentiate the effectiveness of immune checkpoint blockade (ICB) antibodies to inhibit distant tumor growth.

Fabrication of a Dual-Stimuli-Responsive Supramolecular Micelle from a Pillar[5]arene-Based Supramolecular Diblock Copolymer for Photodynamic Therapy.

A pH and thermo dual-responsive supramolecular diblock copolymer is constructed by host-guest recognition of pillar[5]arene and viologen salt. The host polymer, poly(N,N-dimethylaminoethyl methacrylate) bearing pillar[5]arene as the terminal group (P[5]A-PDMAEMA) is synthesized by atom transfer radical polymerization (ATRP). Guest polymer, ethyl viologen-ended poly(N-isopropylacrylamide) (EV-PNIPAM) is prepared by reversible addition-fragmentation chain transfer polymerization. The supramolecular diblock copolymer can be self-assembled into stable supramolecular nanoparticles in aqueous solution at 40 °C, which show excellent pH and thermo responsiveness. The nanoparticles are further applied in the encapsulation of photosensitizers (pyropheophorbide-a, PhA) for photodynamic therapy (PDT). The dual-responsive nanoparticles can efficiently release PhA in acidic environment at 25 °C. Based on the result of cell experiments, PhA-loaded nanomicelles exhibit excellent PDT efficacy and low dark toxicity toward A549 cells. Thus, this supramolecular diblock copolymer enriches the methodology of constructing stimuli-responsive drug carriers and presents a great potential in PDT.

Enhanced photodynamic therapy efficacy by encapsulation of photosensitizers in tyrosine-derived nanospheres

Enhanced photodynamic therapy efficacy by encapsulation of photosensitizers in tyrosine-derived nanospheres

Abstract 5396: Nanoparticles loaded with indium (III) phthalocyanine are more effective in promoting cell proliferation inhibition on MCF-7 breast cancer cells when compared to free InPc

Abstract Background: Indium (III) phthalocyanine (InPc) was encapsulated into nanoparticles (NP) of PEGylated poly (D,L-lactide-co-glycolide) (PLGA-PEG) to improve the photobiological activity of the photosensitizer. The efficacy of NP loaded with InPc and their cellular uptake was investigated with MCF-7 cells, and compared with the free InPc. Methods: NP were prepared by the method of emulsion/evaporation. The emulsion was washed and centrifuged and lyophilized. The lyophilized particles were characterized via scanning electron microscopy. The evaluation of the cell suspensions viability incubated with InPc free and encapsulated and subsequently irradiated with a 665 nm laser diode was performed at different concentrations of InPc (1.8-7.5 mol/L), incubation times (1-2h) and laser power (10-100mW) by MTT assay. The internalization of the InPc free and encapsulated cells was assessed via confocal microscopy. Measurement of absorbance spectra and fluorescence of free and encapsulated InPc were monitored during irradiation assessment photodegradation to the photosensitizer. The generation of singlet oxygen was monitored by electron paramagnetic resonance spectroscopy. Findings: The influence of photosensitizer (PS) concentration (1.8-7.5 mol/L), incubation time (1-2h), and laser power (10-100mW) were studied on the photodynamic effect caused by the encapsulated and the free InPc. NP with a size distribution ranging from 61 to 243 and with InPc entrapment efficiency of 72±6% were used in the experiments. Only the photodynamic effect of encapsulated InPc was dependent on PS concentration and laser power. The InPc loaded NP were more efficient in reducing MCF-7 cell viability than the free PS. For a light dose of 7.5 J/cm2 and laser power of 100 mW, the effectiveness of encapsulated InPc to reduce the viability was 34±3 % while for free InPc was 60±7 %. Confocal microscopy showed that InPc-loaded NP, as well as free InPc, were found throughout the cytosol. The NP aggregates and the aggregates of free PS were found in the cell periphery and outside of the cell. The NP aggregates were generated due to the particles concentration used in the experiment because of the small loading of the InPc while the low solubility of InPc caused the formation of aggregates of free PS in the culture medium. The participation of singlet oxygen in the photocytotoxic effect of InPc-loaded NP was corroborated by electron paramagnetic resonance experiments, and the encapsulation of photosensitizers reduced the photobleaching of InPc. Interpretation: The InPc encapsulated was more effective in reducing the MCF-7 viability compared to InPc free due to increased internalization of InPc encapsulated in tumor cells due to the aggregate state of the InPc free hampering the generation of singlet oxygen. Note: This abstract was not presented at the meeting. Citation Format: Carlos Augusto Zanoni Souto, Klesia Pirola Madeira, Leticia Rangel, André Romero da Silva. Nanoparticles loaded with indium (III) phthalocyanine are more effective in promoting cell proliferation inhibition on MCF-7 breast cancer cells when compared to free InPc. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5396. doi:10.1158/1538-7445.AM2014-5396

Encapsulation of Photosensitizers and Upconversion Nanocrystals in Lipid Micelles for Photodynamic Therapy

Photodynamic therapy (PDT) is a promising method for cancer therapy. However, it is constrained by limited penetration depth of visible light, hydrophobicity of photosensitizers, and lack of tumor targeting. In this work, the photosensitizer zinc phthalocyanine (ZnPc) and upconversion nanocrystals (UCNs) are encapsulated into OQPGA‐PEG/RGD/TAT lipid micelles. The UCNs acting as a nanotransducer convert deep‐penetrating near‐infrared (NIR) light to visible light for activating the photosensitizer. OQPGA‐PEG/RGD/TAT lipid micelles are used as a carrier for the photosensitizer, with improved biocompatibility and cancer‐targeting ability. The results show that the photosensitizer ZnPc‐ and UCNs‐loaded OQPGA‐PEG/RGD/TAT lipid micelles are nanoparticles with an average size of 25 nm. The lipid micelle nanoparticles are stable in water with low leakage of photosensitizer. The absorption peak of the photosensitizer overlaps with the emission peak of UCNs, so the visible fluorescence emitted from the UCNs upon excitation by the NIR laser at 980 nm can activate the photosensitizer to produce singlet oxygen for PDT. The targeting RGD peptide and cell‐penetrating TAT peptide on the surface help the nanoparticles getting into cancer cells. The OQPGA‐PEG/RGD/TAT lipid micelles encapsulated with both the photosensitizer ZnPc and UCNs could be used for targeted PDT by using deep‐penetrating NIR light as the light source.

Encapsulation of Photosensitizers in Hexa- and Octanuclear Organometallic Cages: Synthesis and Characterization of Carceplex and Host–Guest Systems in Solution

Cationic arene ruthenium assemblies of the general formulas [Ru6(p-cymene)6(tris-pvb)2(μ2-Cl)6]6+, [Ru6(p-cymene)6(tris-pvb)2(OO∩OO)3]6+ (tris-pvb = 1,3,5-tris{2-(pyridin-4-yl)vinyl}benzene), and [Ru8(p-cymene)8(NN∩NN)2(OO∩OO)4]8+ (NN∩NN = 1,2,4,5-tetrakis{2-(pyridin-4-yl)vinyl}benzene, 1,2,4,5-tetrakis{2-(pyridin-4-yl)ethynyl}benzene) have been obtained from the corresponding dinuclear arene ruthenium complexes [Ru2(p-cymene)2(μ-Cl)2Cl2] and [Ru2(p-cymene)2(OO∩OO)Cl2] (OO∩OO = oxalato, 2,5-dioxido-1,4-benzoquinonato, 2,5-dichloro-1,4-benzoquinonato, 5,8-dioxido-1,4-naphthoquinonato, 5,8-dioxido-1,4-anthraquinonato, 6,11-dioxido-5,12-naphthacenedionato) by reaction with the multidentate ligands and silver trifluoromethanesulfonate. These cationic hexa- and octanuclear cages have been isolated and characterized as their triflate salts. Addition of coronene during the synthesis of the large hexanuclear assemblies leads to the direct encapsulation of coronene in the cavity of the trigonal-prismatic complexes. Photosensitizers such as porphin, phthalocyanine, and Zn-phthalocyanine present during the synthesis of these metalla-cages are encapsulated in five of these arene ruthenium complexes to give photosensitizer-encapsulated systems. The host–guest properties of these systems were studied in solution by DOSY, 2D NOESY and 2D ROESY NMR spectroscopy. The H···H distances between guests and selected metalla-cages were estimated by 2D ROESY NMR spectroscopy and modelization. NMR analyzes indicate that the guest photosensitizers are completely encapsulated in two of these metalla-cages, while in the three other ruthenium cages NMR spectra reveal an equilibrium between empty and filled cages.

Encapsulation of Photosensitizer into Multilayer Microcapsules by Combination of Spontaneous Deposition and Heat‐Induced Shrinkage for Photodynamic Therapy

Annealing of PDADMAC/PSS multilayer microcapsules assembled on PSS-doped CaCO(3) particles at 80 °C for 30 min reduces their size dramatically from 6.9 ± 0.3 to 3.1 ± 0.5 µm. Methylene blue molecules are encapsulated by spontaneous deposition and post-annealing with a concentration of 22 mg · mL(-1), which is 1000 times higher than the feeding value. The unreleased MB molecules are retained stably for a long time, which are then protected by the capsules against reductive enzymes and keep their photodynamic activity. The viability of HeLa cells incubated with the MB-loaded capsules decreases sharply from ≈ 75 (dark cytotoxicity) to ≈ 20% after irradiation with a laser at 671 nm and 60 J · cm(-2) for 75 s.

Photodynamic antimicrobial chemotherapy by liposome-encapsulated water-soluble photosensitizers

Photodynamic antimicrobial chemotherapy is an alternative method for killing bacterial cells in view of the increasing problem of multi-antibiotic resistance. We examined the effect of three water-soluble photosensitizers (PhS): methylene blue (MB), neutral red (NR) and rose bengal (RB) on Gram-positive and Gram-negative bacteria. We compared the efficacy of PhS in their free form and encapsulated in liposomal formulations against various bacterial strains, and determined conditions for the effective use of encapsulated PhS. We found that all three PhS were able to eradicate the Gram-positive microbes Staphylococcus aureus and Sarcina lutea; and MB and RB were effective against St. epidermidis. In the case of the Gram-negative species, MB and RB were cytotoxic against the Shigella flexneri, NR-inactivated Escherichia coli and Salmonella para B, and BR was effective in killing Pseudomonas aeruginosa. None of the examined PhS showed activity against Klebsiella pneumoniae. MB and NR enclosed in liposomes gave a stronger antimicrobial effect than free PhS for all tested prokaryotes, whereas encapsulation of RB led to no increase in its activity. We suggest that encapsulation of PhS can increase the photoinactivation of bacteria.

Monomeric pheophorbide(a)-containing poly(ethyleneglycol-b-ε-caprolactone) micelles for photodynamic therapy

Incorporation of unaggregated monomeric molecules of pheophorbide(a) into micelles of poly(ethyleneoxide-b-epsilon-caprolactone) has been characterized by fluorescence spectroscopy, dynamic light scattering, transmission electron microscopy and asymmetric flow field flow fractionation. It was shown that the method used leads to 20 nm micelles, corresponding to approximately 200 molecules of polymer and 4 molecules of monomeric pheophorbide(a) per nano-object which was able to generate (1)O(2) in the medium. They have been used thereafter as nanocarriers for photosensitizers in photodynamic therapy against cancer cells. The encapsulation of photosensitizer has been verified and in vitro tests on human cancerous cells have revealed a ca. 2-fold enhanced photocytotoxicity and cellular uptake compared to free pheophorbide(a).