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1

CGP 55398, a liposomal Ge(IV) phthalocyanine bearing two axially ligated cholesterol moieties: a new potential agent for photodynamic therapy of tumours.  

PubMed Central

Ge(IV) phthalocyanine (GePc) with two axially ligated cholesterol moieties was prepared by chemical synthesis and incorporated in a monomeric state into small unilamellar liposomes (CGP 55398). Upon photoexcitation with light wavelengths around its intense absorption peak at 680 nm, GePc shows an efficient photosensitising activity towards biological substrates through a mechanism which largely involves the intermediacy of singlet oxygen. GePc injected systemically into mice bearing an intramuscularly implanted MS-2 fibrosarcoma is quantitatively transferred to serum lipoproteins and localises in the tumour tissue with good efficiency: at 24 h post injection the GePc content in the tumour is 0.74 and 1.87 micrograms per g of tissue with a tumour/peritumoral ratio of 4.35 and 5.67 for injected doses of 0.76 and 1.52 mg kg-1 respectively. At this time the red-light irradiation of the GePc-loaded fibrosarcoma causes a fast and massive tumour necrosis involving both malignant cells and blood vessels. Images Figure 8 Figure 9 Figure 10 Figure 11 Figure 12

Segalla, A.; Milanesi, C.; Jori, G.; Capraro, H. G.; Isele, U.; Schieweck, K.

1994-01-01

2

Photodynamic efficacy of water-soluble Si(IV) and Ge(IV) phthalocyanines towards Candida albicans planktonic and biofilm cultures.  

PubMed

Water-soluble phthalocyanine complexes of silicon (SiPc1) and germanium (GePc1) were synthesized. The absorbance of SiPc1 in water was with minor aggregation while GePc1 strongly aggregated in water. The fluorescence data in water showed low quantum yields of 0.073 (SiPc1) and 0.01 (GePc1) and similar lifetimes of 4.07 ns and 4.27 ns. The uptake of SiPc1 into Candida albicans cells was two orders of magnitude lower as compared to GePc1 and for both was dependent on the cell density. Fungal cells in suspension were completely inactivated after SiPc1 (1.8 ?M) at soft light radiation (50 J cm(-2), 60 mW cm(-2)). The fungal biofilm formed on denture acrylic resin was inactivated with 3 log after fractionated light irradiation. PMID:21816518

Mantareva, Vanya; Angelov, Ivan; Kussovski, Veselin; Dimitrov, Roumen; Lapok, Lukasz; Wöhrle, Dieter

2011-07-19

3

Large-scale production of liposomes containing monomeric zinc phthalocyanine by controlled dilution of organic solvents.  

PubMed

This work describes the development of an organic solvent dilution method suitable for the large scale manufacturing of small unilamellar liposomes containing the water-insoluble photosensitizer zinc phthalocyanine in the monomeric state. N-Methyl pyrrolidone (NMP)/tert-butyl alcohol was selected as water miscible organic phase in which the phospholipids 1-palmitoyl, 2-oleoylphosphatidylcholine (POPC), and 1,2-dioeloylphosphatidylserine (OOPS) and the dye were dissolved. This organic phase was mixed with an excess of a water phase using a dynamic mixing device, yielding reproducibly unilamellar liposomes with a mean size of 50-150 nm as measured with quasielastic light scattering. After concentration, the organic solvents were efficiently removed by cross-flow filtration. The liposomes were then sterile filtered and freeze-dried. A method to measure the aggregation state of the dye in the liposomes was developed. A stable lyophilized formulation containing monomeric liposomal ZnPc could be obtained by using a solution of ZnPc in NMP (2 mg/mL) and ZnPc/phospholipid (1:100 w/w ratio) and performing concentration and dialysis at 4 degrees C and lyophilization in presence of a mixture of lactose and phospholipid (5:1 w/w ratio). PMID:7891283

Isele, U; van Hoogevest, P; Hilfiker, R; Capraro, H G; Schieweck, K; Leuenberger, H

1994-11-01

4

Pharmaceutical development of CGP 55847: a liposomal Zn-phthalocyanine formulation using a controlled organic solvent dilution method  

NASA Astrophysics Data System (ADS)

Liposomes were prepared containing zinc-phthalocyanine (ZnPc). The composition was ZnPc/POPC/OOPS (1:90:10 w/w /w). The phospholipids (PL) were dissolved in t-butanol at 50 degree(s)C under magnetic stirring and mixed with ZnPc, dissolved in NMP for two hours in an ultrasonic bath at 80 degree(s)C. This mixture (50 degree(s)C) was diluted with lactose- NaCl solution (9.475% lactose, 0.027% NaCl) at 4 degree(s)C using a dynamic mixer. The collected liposomal suspension was concentrated first, to 20 mg PL/ml suspension and then the organic solvents were removed by tangential flow filtration (CentrasetteR) against a ten fold volume of lactose-NaCl solution. After sterile filtration the liposomal suspension was freeze-dried for 24 hours.

Isele, Ute; van Hoogevest, Peter; Leuenberger, Hans; Capraro, Hans-Georg; Schieweck, Klaus

1994-03-01

5

METAL PHTHALOCYANINES  

DOEpatents

A process is given for preparing heavy metal phthalocyanines, sulfonated or not. The process comprises mixing an inorganic metal salt with dimethyl formamide or methyl sulfoxide; separating the metal complex formed from the solution; mixing the complex with an equimolar amount of sodium, potassium, lithium, magnesium, or beryllium sulfonated or unsulfonated phthalocyanine whereby heavy-metal phthalocyanine crystals are formed; and separating the crystals from the solution. Uranyl, thorium, lead, hafnium, and lanthanide rare earth phthalocyanines can be produced by the process. (AEC)

Frigerio, N.A.

1962-03-27

6

Comparison of two phthalocyanines for PDT  

NASA Astrophysics Data System (ADS)

Photodynamic therapy (PDT) is a new treatment modality for bladder carcinoma, especially carcinoma in situ. The goal of our study was to compare two different phthalocyanines for PDT of bladder carcinoma cells and to evaluate phototoxic potential. Material and methods: For PDT hydrophilic chlor-aluminum sulfonated phthalocyanine (CASP) and lipophilic zinc- phthalocyanine (ZnP, CPG 55 847) were compared. For ZnP liposomes as drug carrier were used. The photosensitizer concentrations for both substances used for PDT experiments were 5, 10 and 20 (mu) g/ml. Irradiation was performed with a Penta lamp emitting at wavelengths between 590 and 900 nm at a fluence of up to 12 J/cm2. After irradiation cells were incubated for two days, counted and compared with a control group. Results: The cell survival rate was decreased depending on the light and drug dose. After incubation with the highest drug dose and irradiation with 12 J/cm2 cell survival was 0.03 and 5.5% after incubation with CASP or ZnP, respectively. Light, CASP or ZnP alone had no effect on cells. Studies of the PDT effect by electron microscopy showed intracellular vacuolization caused by mitochondrial damage after incubation with either photosensitizer. Conclusion: The hydrophilic and lipophilic phthalocyanine tested here showed very similar effects on our cell line. ZnP is a pure compound and hence has some advantage over CASP, which is a mixture of a tri- and tetrasulfonated phthalocyanine. In addition, ZnP is administered in liposomes which should enhance tumor selectivity by binding to low density lipoprotein receptors on tumor cells.

Bachor, Ruediger; Reich, Ella; Graf, Peter; Rueck, Angelika C.; Hautmann, Richard E.

1996-01-01

7

Method of solubilizing phthalocyanines and metallophthalocyanines.  

National Technical Information Service (NTIS)

A one-step method of manufacturing soluble phthalocyanines and metallophthalocyanines, like zinc phthalocyanine, by converting a phthalocyanine or a metallophthalocyanine to a trialkylsilyl-substituted derivative is disclosed. The phthalocyanine or metall...

J. W. Rathke M. J. Chen C. M. Fendrick

1990-01-01

8

Phthalocyanines. Vol. 1. Properties  

SciTech Connect

These two volumes assemble extensive knowledge of the properties, preparation, manufacture, applications and polymers of phthalocyanines. Over 50 diagrams illustrate the phthalocyanine molecule in a variety of configurations and its brilliant and clean blue and green colors. Crystalline forms, reactions, radiation chemistry, catalytic properties, physical properties including absorption spectra, luminescence, Raman spectra, photoelectron spectroscopy or electron spectroscopy for chemical analysis, Mossbauer spectroscopy and x-ray analysis are just some of the aspects covered. The preparations of 63 known metal phthalocyanines are described. Phthalocyanines used in catalysis, colorants, lasers, lubricants and greases, photography and xerography are discussed in detail. The volumes are appended with review references, test procedures, trade names and manufacturers, and production data.

Moser, F.H.

1983-01-01

9

Metal Phthalocyanine Polymers.  

National Technical Information Service (NTIS)

Metal 4, 4', 4', 4'-tetracarboxylic phthalocyanines (MPTC) are prepared by reaction of trimellitic anhydride, a salt or hydroxide of the desired metal (or the metal in powdered form), urea and a catalyst. A purer form of MPTC is prepared than heretofore. ...

B. N. Achar G. M. Fohlen J. A. Parker

1982-01-01

10

Photodynamic ultradeformable liposomes: Design and characterization.  

PubMed

Hydrophobic ([tetrakis(2,4-dimetil-3-pentyloxi)-phthalocyaninate]zinc(II)) (ZnPc) and hydrophilic ([tetrakis(N,N,N-trimethylammoniumetoxi)-phthalocyaninate]zinc(II) tetraiodide) (ZnPcMet) phthalocyanines were synthesized and loaded in ultradeformable liposomes (UDL) of soybean phosphatidylcholine and sodium cholate (6:1, w/w, ratio), resulting 100 nm mean size vesicles of negative Zeta potential, with encapsulation efficiencies of 85 and 53%, enthalpy of phase transition of 5.33 and 158 J/mmol for ZnPc and ZnPcMet, respectively, indicating their deep and moderate partition into UD matrices. Matrix elasticity of UDL-phthalocyanines resulted 28-fold greater than that of non-UDL, leaking only 25% of its inner aqueous content after passage through a nanoporous barrier versus 100% leakage for non-UDL. UDL-ZnPc made ZnPc soluble in aqueous buffer while kept the monomeric state, rendering singlet oxygen quantum yield (Phi(Delta)) similar to that obtained in ethanol (0.61), whereas UDL-ZnPcMet had a four-fold higher Phi(Delta) than that of free ZnPcMet (0.21). Free phthalocyanines were non-toxic at 1 and 10 microM, both in dark or upon irradiation at 15 J/cm2 on Vero and J-774 cells (MTT assay). Only liposomal ZnPc at 10 microM was toxic for J-774 cells under both conditions. Additionally, endo-lysosomal confinement of the HPTS dye was kept after irradiation at 15 J/cm2 in the presence of UDL-phtalocyanines. This could lead to improve effects of singlet oxygen against intra-vesicular pathogen targets inside the endo-lysosomal system. PMID:17157460

Montanari, J; Perez, A P; Di Salvo, F; Diz, V; Barnadas, R; Dicelio, L; Doctorovich, F; Morilla, M J; Romero, E L

2006-11-11

11

Method of solubilizing phthalocyanines and metallophthalocyanines  

DOEpatents

A one-step method of manufacturing soluble phthalocyanines and metallophthalocyanines, like zinc phthalocyanine, by converting a phthalocyanine or a metallophthalocyanine to a trialkylsilyl-substituted derivative is disclosed. The phthalocyanine or metallophthalocyanine is converted to a soluble trialkylsilyl-substituted derivative by interacting the phthalocyanine or metallophthalocyanine with an active metal amide, like lithium 2,2,6,6-tetramethylpiperidide, and a halotrialkylsilane, like chlorotrimethylsilane, to provide a phthalocyanine compound, like phthalocyanine monomers, dimers or polymers, metalated or unmetalated, that are soluble in organic media.

Rathke, Jerome W. (Bolingbrook, IL); Chen, Michael J. (Darien, IL); Fendrick, Carol M. (Downers Grove, IL)

1997-01-01

12

Method of solubilizing phthalocyanines and metallophthalocyanines  

DOEpatents

A one-step method of manufacturing soluble phthalocyanines and metallophthalocyanines, like zinc phthalocyanine, by converting a phthalocyanine or a metallophthalocyanine to a trialkylsilyl-substituted derivative is disclosed. The phthalocyanine or metallophthalocyanine is converted to a soluble trialkylsilyl-substituted derivative by interacting the phthalocyanine or metallophthalocyanine with an active metal amide, like lithium 2,2,6, 6-tetra-methylpiperidide, and a halotrialkylsilane, like chlorotrimethylsilane, to provide a phthalocyanine compound, like phthalocyanine monomers, dimers or polymers, metalated or unmetalated, that are soluble in organic media.

Rathke, J.W.; Chen, M.J.; Fendrick, C.M.

1990-06-01

13

Monolayer-Forming Substituted Phthalocyanine Compounds.  

National Technical Information Service (NTIS)

This invention relates general to phthalocyanine compounds, and more particularly to the preparation of aryloxy, arylthio, alkyloxy, and alkylthio phthalocyanine compounds and their subsequent incorporation into semiconducting thin films by the Langmuir-B...

W. R. Barger N. L. Jarvis A. W. Snow H. Wohltjen

1985-01-01

14

The use of phthalocyanines in cancer therapy  

NASA Astrophysics Data System (ADS)

Phthalocyanines are synthetic analogues of porphyrins employed as photosensitizers in cancer therapy. We present the history of photodynamic therapy and developments in the use of phthalocyanines as photosensitizers. New efforts in the development of more cancer-specific phthalocyanines are presented. The combination of phthalocyanines with nanoparticles for "combination therapy" of cancer is also discussed. The nanoparticles employed are quantum dots, gold, and magnetic nanoparticles.

Nyokong, Tebello; Gledhill, Igle

2013-03-01

15

Phthalocyanine cathode materials for secondary lithium cells  

SciTech Connect

Discharge and charge characteristics of various phthalocyanine cathodes coupled with lithium metal are studied. The best capacity based only on cathode active material weight is 1440 A-hr/kg in the lithium/iron phthalocyanine system, and the cycle life of the lithium/Cu phthalocyanine system is more than 100 times at the discharge depth of 157 A-hr/kg. The cathode reaction mechanism is supposed to be lithium intercalation between phthalocyanine molecules. The results indicate that these phthalocyanines are promising cathode active materials for lithium secondary batteries. 15 refs.

Yamaki, J.; Yamaji, A.

1982-01-01

16

Phthalocyanine cathode materials for secondary lithium cells  

SciTech Connect

Discharge and charge characteristics of various phthalocyanine cathodes coupled with lithium metal are studied. The best capacity based only on cathode active material weight is 1440 A-hr/kg in the lithium/iron phthalocyanine system, and the cycle life of the lithium/Cu phthalocyanine system is more than 100 times at the discharge depth of 157 A-hr/kg. The cathode reaction mechanism is supposed to be lithium intercalation between phthalocyanine molecules. The results indicate that these phthalocyanines are promising cathode active materials for lithium secondary batteries.

Tamaki, J.; Yamaji, A.

1982-01-01

17

Doped colorimetric assay liposomes  

DOEpatents

The present invention provides compositions comprising colorimetric assay liposomes. The present invention also provides methods for producing colorimetric liposomes and calorimetric liposome assay systems. In preferred embodiments, these calorimetric liposome systems provide high levels of sensitivity through the use of dopant molecules. As these dopants allow the controlled destabilization of the liposome structure, upon exposure of the doped liposomes to analyte(s) of interest, the indicator color change is facilitated and more easily recognized.

Charych, Deborah (Albany, CA); Stevens, Raymond C. (Albany, CA)

2001-01-01

18

In vivo monitoring of liposomal release in tumours following ultrasound stimulation.  

PubMed

Dioeleoylphosphatidylethanolamine (DOPE)-based liposomes were recently reported as a new class of liposomes for ultrasound (US)-mediated drug delivery. The liposomes showed both high stability and in vitro US-mediated drug release (sonosensitivity). In the current study, in vivo proof-of-principle of US triggered release in tumoured mice was demonstrated using optical imaging. Confocal non-thermal US was used to deliver cavitation to tumours in a well-controlled manner. To detect in vivo release, the near infrared fluorochrome Al (III) Phthalocyanine Chloride Tetrasulphonic acid (AlPcS?) was encapsulated into both DOPE-based liposomes and control liposomes based on hydrogenated soy phosphatidylcholine (HSPC). Encapsulation causes concentration dependent quenching of fluorescence that is recovered upon AlPcS? release from the liposomes. Exposure of tumours to US resulted in a significant increase in fluorescence in mice administered with DOPE-based liposomes, but no change in the mice treated with HSPC-based liposomes. Thus, DOPE-based liposomes showed superior sonosensitivity compared to HSPC-based liposomes in vivo. PMID:23274944

Evjen, Tove J; Hagtvet, Eirik; Moussatov, Alexei; Røgnvaldsson, Sibylla; Mestas, Jean-Louis; Fowler, R Andrew; Lafon, Cyril; Nilssen, Esben A

2012-12-27

19

Synthesis of Monometallated and Unsymmetrically Substituted Binuclear Phthalocyanines and a Pentanuclear Phthalocyanine by Solution and Polymer Support Methods.  

National Technical Information Service (NTIS)

Binuclear phthalocyanines in which two different phthalocyanine nuclei are covalently linked through five-atom bridges, derived from 2-ethyl-2-methylpropan-1,3-diol are prepared. In the examples, one phthalocyanine ring is always substituted with neopento...

B. Khouw C. C. Leznoff P. Seymour P. I. Svirskaya R. L. Cerny

1990-01-01

20

Phthalocyanine Blends Improve Bulk Heterojunction Solar Cells  

PubMed Central

A core phthalocyanine platform allows engineering the solubility properties the band gap; shifting the maximum absorption toward the red. A simple method to increase the efficiency of heterojunction solar cells uses a self-organized blend of the phthalocyanine chromophores fabricated by solution processing.

Varotto, Alessandro; Nam, Chang-Yong; Radivojevic, Ivana; Tome, Joao; Cavaleiro, Jose A.S.; Black, Charles T.; Drain, Charles Michael

2010-01-01

21

Novel applications of liposomes  

Microsoft Academic Search

Opinions of the usefulness of liposomes in various biotechnological applications range from unsubstantiated optimism to undeserved pessimism. This article reviews the background and development of liposomes, describes products that are commercially available and speculates optimistically about some future applications. The current deepening and widening of interest in liposomes in many scientific disciplines, and their application in medicine, immunology, diagnostics, cosmetics,

Dan D Lasic

1998-01-01

22

Phthalocyanines functionalized with 2-methyl-5-nitro-1H-imidazolylethoxy and 1,4,7-trioxanonyl moieties and the effect of metronidazole substitution on photocytotoxicity.  

PubMed

Four novel magnesium(II) and zinc(II) phthalocyanines bearing 1,4,7-trioxanonyl, polyether and/or (2-methyl-5-nitro-1H-imidazol-1-yl)ethoxy, heterocyclic substituents at their non-peripheral positions were synthesized and assessed in terms of physicochemical and biological properties. Magnesium phthalocyanine derivatives bearing polyether substituents (Pc-1), a mixed system of polyether and heterocyclic substituents (Pc-3), and four heterocyclic substituents (Pc-4), respectively, were synthesized following the Linstead macrocyclization reaction procedure. Zinc phthalocyanine (Pc-2) bearing polyether substituents at non-peripheral positions was synthesized following the procedure in n-pentanol with the zinc acetate, and DBU. Novel phthalocyanines were purified by flash column chromatography and characterized using NMR, MS, UV-Vis and HPLC. Moreover, two precursors in macrocyclization reaction phthalonitriles were characterized using X-ray. Photophysical properties of the novel macrocycles were evaluated, including UV-Vis spectra analysis and aggregation study. All macrocycles subjected to singlet oxygen generation and the oxidation rate constant measurements exhibited lower quantum yields of singlet oxygen generation in DMSO than in DMF. In addition, the Pc-2 molecule was found to be the most efficient singlet oxygen generator from the group of macrocycles studied. The photocytotoxicity evaluated on the human oral squamous cell carcinoma cell line, HSC-3, for Pc-3 was significantly higher than that for Pc-1, Pc-2, and Pc-4. Interestingly, Pc-3 was found to be the most active macrocycle in vitro although its ability to generate singlet oxygen was significantly lower than those of Pc-1 and Pc-2. However, attempts to encapsulate phthalocyanines Pc-1-Pc-3 in liposomal membranes were unsuccessful. The phthalocyanine-nitroimidazole conjugate, Pc-4 was encapsulated in phosphatidylglycerol:phosphatidylcholine unilamellar liposomes and subjected to photocytotoxicity study. PMID:23872453

Wierzchowski, Marcin; Sobotta, Lukasz; Skupin-Mrugalska, Paulina; Kruk, Justyna; Jusiak, Weronika; Yee, Michael; Konopka, Krystyna; Düzgüne?, Nejat; Tykarska, Ewa; Gdaniec, Maria; Mielcarek, Jadwiga; Goslinski, Tomasz

2013-06-28

23

Hexacoordinate bonding and aromaticity in silicon phthalocyanine.  

PubMed

Si-E bondings in hexacoordinate silicon phthalocyanine were analyzed using bond order (BO), energy partition, atoms in molecules (AIM), electron localization function (ELF), and localized orbital locator (LOL). Bond models were proposed to explain differences between hexacoordinate and tetracoordinate Si-E bondings. Aromaticity of silicon phthalocyanine was investigated using nucleus-independent chemical shift (NICS), harmonic oscillator model of aromaticity (HOMA), conceptual density functional theory (DFT), ring critical point (RCP) descriptors, and delocalization index (DI). Structure, energy, bonding, and aromaticity of tetracoordinate silicon phthalocyanine were studied and compared with hexacoordinate one. PMID:21105726

Yang, Yang

2010-11-24

24

The Phthalocyanines. Vol. 2 Manufacture and Applications  

SciTech Connect

These two volumes assemble extensive knowledge of the properties, preparation, manufacture, applications and polymers of phthalocyanines. Over 50 diagrams illustrate the phthalocyanine molecule in a variety of configurations and its brilliant and clean blue and green colors. Crystalline forms, reactions, radiation chemistry, catalytic properties, physical properties including absorption spectra, luminescence, Raman spectra, photoelectron spectroscopy or electron spectroscopy for chemical analysis, Mossbauer spectroscopy and x-ray analysis are just some of the aspects covered. The preparations of 63 known metal phthalocyanines are described. Phthalocyanines used in catalysis, colorants, lasers, lubricants and greases, photography and xerography are discussed in detail. The volumes are appended with review references, test procedures, trade names and manufacturers, and production data.

Moser, F.H.; Thomas, A.L.

1983-01-01

25

Adsorption of ammonia on multilayer iron phthalocyanine  

SciTech Connect

The adsorption of ammonia on multilayers of well-ordered, flat-lying iron phthalocyanine (FePc) molecules on a Au(111) support was investigated by x-ray photoelectron spectroscopy. We find that the electron-donating ammonia molecules coordinate to the metal centers of iron phthlalocyanine. The coordination of ammonia induces changes of the electronic structure of the iron phthalocyanine layer, which, in particular, lead to a modification of the FePc valence electron spin.

Isvoranu, Cristina; Knudsen, Jan; Ataman, Evren; Andersen, Jesper N.; Schnadt, Joachim [Division of Synchrotron Radiation Research, Department of Physics, Lund University, Box 118, 221 00 Lund (Sweden); Schulte, Karina [MAX-lab, Lund University, Box 118, 221 00 Lund (Sweden); Wang Bin; Bocquet, Marie-Laure [Laboratoire de chimie, Ecole normale superieure de Lyon, 46, Allee d'Italie, 69364 Lyon Cedex 07 (France)

2011-03-21

26

Liposome-Incorporation of Polyenes.  

National Technical Information Service (NTIS)

The invention involves a liposomal agent for treating disseminated fungal infection in an animal. This liposomal agent comprises a variety of polyene antifungal compounds. The various polyene antifungal compounds of the liposomal agent include hamycin, lu...

G. Lopez-Berestein R. Mehta

1991-01-01

27

Liposomal formulations for inhalation.  

PubMed

No marketed inhaled products currently use sustained release formulations such as liposomes to enhance drug disposition in the lung, but that may soon change. This review focuses on the interaction between liposomal formulations and the inhalation technology used to deliver them as aerosols. There have been a number of dated reviews evaluating nebulization of liposomes. While the information they shared is still accurate, this paper incorporates data from more recent publications to review the factors that affect aerosol performance. Recent reviews have comprehensively covered the development of dry powder liposomes for aerosolization and only the key aspects of those technologies will be summarized. There are now at least two inhaled liposomal products in late-stage clinical development: ARIKACE(®) (Insmed, NJ, USA), a liposomal amikacin, and Pulmaquin™ (Aradigm Corp., CA, USA), a liposomal ciprofloxacin, both of which treat a variety of patient populations with lung infections. This review also highlights the safety of inhaled liposomes and summarizes the clinical experience with liposomal formulations for pulmonary application. PMID:23919478

Cipolla, David; Gonda, Igor; Chan, Hak-Kim

2013-08-01

28

Doxorubicin hydrochloride liposome injection  

Center for Drug Evaluation (CDER)

... being exercised, Sun Pharma Global's Lipodox (Doxorubicin Hydrochloride Liposome Injection) remains unapproved by FDA for marketing in the ... More results from www.fda.gov/drugs/informationondrugs/approveddrugs

29

Assignment of the optical spectra of metal phthalocyanine anions  

SciTech Connect

Magnetic circular dichroism (MCD) spectroscopy was used to create a general band assignment scheme for main group and transition metal phthalocyanine anion species. The complexity of the overlapping absorption spectra of metal phthalocyanine anion species has been troublesome when creating models of the electronic structure of the phthalocyanine ring. The ZINDO program was used for molecular orbital calculations. 56 refs., 14 figs., 5 tabs.

Mack, J.; Stillman, M.J. [Univ. of Western Ontario, London (Canada)

1997-01-29

30

Structure and electrical conduction properties of phthalocyanine thin films  

Microsoft Academic Search

The structure and the dc and ac electrical conduction properties of evaporated phthalocyanine thin films are critically reviewed.Results of various structural studies on phthalocyanine single crystals and thin films performed using X-ray diffraction methods are described, and reported unit cell dimensions are given for several phthalocyanines in both the metastable ? and the stable ? forms: reported unit cell dimensions

R. D. Gould

1996-01-01

31

Binding to and photo-oxidation of cardiolipin by the phthalocyanine photosensitizer Pc 4  

PubMed Central

Cardiolipin is a unique phospholipid of the mitochondrial inner membrane. Its peroxidation correlates with release of cytochrome c and induction of apoptosis. The phthalocyanine photosensitizer Pc 4 binds preferentially to the mitochondria and endoplasmic reticulum. Earlier Förster resonance energy transfer studies showed colocalization of Pc 4 and cardiolipin, which suggests cardiolipin as a target of photodynamic therapy (PDT) with Pc 4. Using liposomes as membrane models, we find that Pc 4 binds to cardiolipin-containing liposomes similarly to those that do not contain cardiolipin. Pc 4 binding is also studied in MCF-7c3 cells and those whose cardiolipin content was reduced by treatment with palmitate. Decreased levels of cardiolipin are quantified by thin-layer chromatography. The similar level of binding of Pc 4 to cells, irrespective of palmitate treatment, supports the lack of specificity of Pc 4 binding. Thus, factors other than cardiolipin are likely responsible for the preferential localization of Pc 4 in mitochondria. Nonetheless, cardiolipin within liposomes is readily oxidized by Pc 4 and light, yielding apparently mono- and dihydroperoxidized cardiolipin. If similar products result from exposure of cells to Pc 4-PDT, they could be part of the early events leading to apoptosis following Pc 4-PDT.

Rodriguez, Myriam E.; Kim, Junhwan; Delos Santos, Grace B.; Azizuddin, Kashif; Berlin, Jeffrey; Anderson, Vernon E.; Kenney, Malcolm E.; Oleinick, Nancy L.

2010-01-01

32

Liposomes in investigative dermatology.  

PubMed

Liposomes are microscopic spheres, usually composed of amphiphilic phospholipids. They may be useful without skin penetration if they simply protect or sequester compounds that would otherwise be unstable in the formulation. Liposomes that remain on the skin surface are useful as light-absorbers, agents to deliver color or sunscreens, or as depots for timed-release. Liposomes that penetrate the stratum corneum have the potential to interact with living tissue. Topically applied liposomes can either mix with the stratum corneum lipid matrix or penetrate the stratum corneum by exploiting the lipid-water interface of the intercellular matrix. There are at least four major routes of entry into the skin: pores, hair follicles, columnular spaces and the lipid:water matrix between squames. A major force driving liposome penetration is the water gradient, and flexible liposomes are best able to exploit these delivery opportunities. Some liposomes release their contents extracellularly. Topical application of photosensitizers may be enhanced by encapsulation in liposomes. Higher and longer-lasting drug concentrations may be produced in localized areas of skin, particularly at disease sites where the stratum corneum and the skin barrier function are disrupted. The liposome membrane should be designed to capture lipophilic drugs in the membrane or hydrophilic drugs in the interior. Other types of liposomes can be engineered to be taken up by cells. Once inside cells, the lysosomal sac and clatherin-coated pit are the dead-end destinations for liposomes unless an escape path has been engineered into the liposome. A novel method has been developed to allow delivery into cells of the skin, by escape from the lysosomal sac. These liposomes have been used to topical deliver active DNA repair enzymes from liposomes into epidermal cells and to enhance DNA repair of UV-irradiated skin. From these studies a tremendous amount has been learned about the relationship of DNA damage and skin cancer. Both mutations and immunosuppression appear to be essential to skin cancer and both are induced by DNA damage. DNA damage produces immediate effects by inducing the expression of cytokines, which means that DNA damage can induce signaling in neighboring, undamaged cells. The repair of only a fraction of the DNA damage has a disproportionate effect on the biological responses, clearly demonstrating that not all DNA damage is equivalent. This technology demonstrates that biologically active proteins can be delivered into the cells of skin, and opens up a new field of correcting or enhancing skin cell metabolism to improve human health. PMID:11555329

Yarosh, D B

2001-10-01

33

Therapeutic uses of antioxidant liposomes  

Microsoft Academic Search

This review will focus on the therapeutic uses of antioxidant liposomes. Antioxidant liposomes have a unique ability to deliver\\u000a both lipid- and water-soluble antioxidants to tissues. This review will detail the varieties of antioxidants which have been\\u000a incorporated into liposomes, their modes of administration, and the clinical conditions in which antioxidant liposomes could\\u000a play an important therapeutic role. Antioxidant liposomes

William L. Stone; Milton Smith

2004-01-01

34

Ultrasound-responsive liposomes.  

PubMed

Ultrasound-responsive liposomes are drug-loaded liposomes that contain a small amount of gas (often air). Co-encapsulation of a pharmaceutic along with this gas renders the liposomes acoustically active, allowing for ultrasound imaging as well as controlled release of the contents through ultrasound stimulation. Methods for the facile production of gas-containing liposomes with simultaneous drug encapsulation are available. Conventional procedures are used to prepare liposomes composed of phospholipid and cholesterol, namely, hydration of the lipid film followed by sonication. After sonication, the gas is introduced by one of two methods. The first method involves freezing and lyophilizing the sonicated liposomes in the presence of mannitol, the relevant property of which appears to be that it accentuates freezing damage to the lipid membranes. The other technique employs freezing of liposomes under elevated pressure of the desired gas. The concept of ultrasound-mediated drug delivery has many potential applications to specific clinical conditions such as cancer, thrombus, arterial restenosis, myocardial infarction, and angiogenesis because of its ability to localize the delivery of therapeutic agents that would cause side effects if given in large amounts systemically. PMID:20072876

Huang, Shao-Ling

2010-01-01

35

Effect of axial ligation and delivery system on the tumour-localising and -photosensitising properties of Ge(IV)-octabutoxy-phthalocyanines.  

PubMed Central

Four Ge(IV)-octabutoxy-phthalocyanines (GePcs) bearing two alkyl-type axial ligands were assayed for their pharmacokinetic properties and phototherapeutic efficiency in Balb/c mice bearing an intramuscularly transplanted MS-2 fibrosarcoma. The GePcs were i.v. injected at a dose of 0.35 mumol kg-1 body weight after incorporation into either Cremophor emulsions or small unilamellar liposomes of dipalmitoyl-phosphatidylcholine (DPPC). Both the nature of the delivery system and the chemical structure of the phthalocyanine were found to affect the behaviour of the GePcs in vivo. Thus, Cremophor-administered GePcs invariably yielded a more prolonged serum retention and a larger association with low-density lipoproteins (LDLs) as compared with the corresponding liposome-delivered phthalocyanines. This led to a greater efficiency and selectivity of tumour targeting. These effects were more pronounced for those GePcs having relatively long alkyl chains (hexyl to decyl) in the axial ligands. Maximal tumour accumulation (0.67 nmol per g of tissue) was found for Ge-Pc(hexyl)2 at 24 h after injection. Consistently, the Ge-Pc(hexyl)2, administered via Cremophor, showed the highest phototherapeutic activity towards MS-2 fibrosarcoma.

Soncin, M.; Polo, L.; Reddi, E.; Jori, G.; Kenney, M. E.; Cheng, G.; Rodgers, M. A.

1995-01-01

36

40 CFR 721.9674 - Sulfonated-copper phthalocyanine salt of a triarylmethane dye (generic).  

Code of Federal Regulations, 2010 CFR

...2010-07-01 false Sulfonated-copper phthalocyanine salt of a triarylmethane dye (generic...721.9674 Sulfonated-copper phthalocyanine salt of a triarylmethane dye (generic...generically as sulfonated-copper phthalocyanine salt of a triarylmethane...

2010-07-01

37

40 CFR 721.9674 - Sulfonated-copper phthalocyanine salt of a triarylmethane dye (generic).  

Code of Federal Regulations, 2010 CFR

...2009-07-01 false Sulfonated-copper phthalocyanine salt of a triarylmethane dye (generic...721.9674 Sulfonated-copper phthalocyanine salt of a triarylmethane dye (generic...generically as sulfonated-copper phthalocyanine salt of a triarylmethane...

2009-07-01

38

40 CFR 721.9674 - Sulfonated-copper phthalocyanine salt of a triarylmethane dye (generic).  

Code of Federal Regulations, 2013 CFR

... 2013-07-01 false Sulfonated-copper phthalocyanine salt of a triarylmethane...Substances § 721.9674 Sulfonated-copper phthalocyanine salt of a triarylmethane...identified generically as sulfonated-copper phthalocyanine salt of a...

2013-07-01

39

Probing Photoconductivity in Phthalocyanines by Terahertz Spectroscopy  

Microsoft Academic Search

Liquid crystals (LCs) are a relatively new class of photoconductors. Surprisingly high carrier mobilities have lately been reported in LCs. Although the high molecular order in these systems has been recognized to play an essential role in the high carrier mobilities, the mechanism of charge transport and carrier photogeneration are still not well understood. In this work, we investigate phthalocyanine

Chen Xia; Brian Kubera; Volodimyr Duzhko; Hefei Shi; Kenneth Singer; Jie Shan

2008-01-01

40

Two-photon excitation of aluminium phthalocyanines  

SciTech Connect

A demonstration is given of the feasibility of two-photon excitation of aluminium phthalocyanine and of the pharmaceutical preparation 'Fotosens', used in photodynamic therapy. The excitation source was an Nd:YAG laser emitting at the 1064 nm wavelength. The spectra of the two-photon-excited luminescence were obtained and the two-photon absorption cross sections were determined. (lasers in medicine)

Meshalkin, Yu P; Alfimov, E E; Makukha, V K [Novosibirsk State Technical University, Novosibirsk (Russian Federation); Vasil'ev, N E; Denisov, A N; Ogirenko, A P [Siberian Laser Medicine Centre, Novosibirsk (Russian Federation)

1999-12-31

41

Synthesis and characterization of a triazine containing three phthalocyanines  

Microsoft Academic Search

A new trimeric-s-triazine containing three amino zinc(II) phthalocyanines has been prepared by following the multistep reactions of unsymmetrical substituted phthalocyanines. The zinc(II) phthalocyanine containing an unsymmetrical substituted nitro group was synthesized by means of the well-known statistically mixing method of two different phthalonitriles. 4-Nitrophthalonitrile and 4,5-bis(hexylthio)phthalonitrile were tetramerized in DMF in the presence of zinc acetate at elevated temperature to

Nazan Ozan; Özer Bekaro?lu

2003-01-01

42

Two novel trivacant Keggin-type polytungstates supported manganese carbonyl derivatives synthesized by degradation of metastable [?-XW10O36]8- (X = Ge(IV), Si(IV)).  

PubMed

Two novel trivacant Keggin-type polyoxometallate-based manganese carbonyl derivatives K(8)[(OC)(3)Mn(A-?-H(2)GeW(9)O(34))]·10H(2)O (1) and K(8)[(OC)(3)Mn(A-?-H(2)SiW(9)O(34))]·11H(2)O (2) have been synthesized by degradation of the metastable [?-XW(10)O(36)](8-) (X = Ge(IV), Si(IV)) in CH(3)CN-H(2)O solvent (1 : 2, vol.) and structurally characterized by elemental analyses, IR spectra, thermogravimetric analysis, and single-crystal X-ray diffraction. X-ray diffraction analyses indicate that 1 and 2 are isomorphic and consist of a [(OC)(3)Mn](+) group and a trivacant [A-?-H(2)XW(9)O(34)](8-) fragment, which exhibit the first examples of trivacant Keggin-type metal carbonyl derivatives. Additionally, the electrocatalytic properties of both for NO(2)(-) oxidation have been investigated. PMID:22447253

Zhao, Juan; Wang, Junsheng; Zhao, Junwei; Ma, Pengtao; Wang, Jingping; Niu, Jingyang

2012-03-26

43

Photochemical decontamination of red cell concentrates with the silicon phthalocyanine Pc 4 and red light  

NASA Astrophysics Data System (ADS)

Virus inactivation in red blood cells concentrates (RBCC) is being studied in order to increase the safety of the blood supply. For this purpose we have been studying the silicon phthalocyanine (Pc 4), a photosensitizer activated with red light. Two approaches were used to achieve enhanced selectivity of Pc 4 for virus inactivation. One was formulation of Pc 4 in liposomes that reduce its binding to red cells. The other was the use of a light emitting diode (LED) array emitting at 700 nm. Vesicular stomatitis virus (VSV) infectivity served as an endpoint for virus kill in treated RBCC. Red cell hemolysis and circulatory survival in rabbits served as measures for red cell damage. Treatment of small aliquots of human RBCC with 2 (mu) M Pc 4 in liposomes and 10 J/cm2 of 700 nm LED light in the presence of the quenches of reactive oxygen species glutathione and trolox resulted in 6 log10 inactivation of VSV. Under these conditions hemolysis of treated red cells stored at 4 degree(s)C for 21 days was only slightly above that of control cells. Rabbit RBCC similarly treated circulated with a half life of 7.5 days compared with 10.5 days of control. It is concluded that Pc 4 used as described here may be useful for viral decontamination of RBCC, pending toxicological and clinical studies.

Ben-Hur, Ehud; Zuk, Maria M.; Oetjen, Joyce; Chan, Wai-Shun; Lenny, Leslie; Horowitz, Bernard

1999-07-01

44

Organic thin-film transistors of phthalocyanines  

Microsoft Academic Search

Organic thin-film field-effect transistors (OTFTs) are emerging as attractive candi- dates for low-price, large-area, and flexible circuit applications. A variety of organic com- pounds have been utilized as active semiconductor materials for OTFTs, among which phthalocyanine compounds have attracted considerable attention owing to their remarkable chemical and thermal stability as well as good field-effect performance. Here, we review re- cent

Liqiang Li; Qingxin Tang; Hongxiang Li; Wenping Hu; Xiaodi Yang; Zhigang Shuai; Yunqi Liu; Daoben Zhu

2008-01-01

45

Pegylated Phthalocyanines: Synthesis and Spectroscopic Properties  

PubMed Central

The syntheses and spectroscopic properties of a series of pegylated zinc(II)-phthalocyanines (Zn-Pcs) containing one, two or eight tri(ethylene glycol) chains are described. The single molecular structure of a phthalonitrile precursor containing one hydroxyl and one PEG group, and its unique intermolecular hydrogen bonding are presented. The pegylated Pcs are highly soluble in polar organic solvents and have fluorescence quantum yields in the range 0.08–0.28.

Li, Hairong; Fronczek, Frank R.; Vicente, M. Graca H.

2011-01-01

46

Soluble phthalocyanines as optical gas sensing materials  

NASA Astrophysics Data System (ADS)

A novel soluble phthalocyanine compound, i.e zinc phthalocyanine (sulfonamide) has been synthesized by chemical substitution of zinc phthalocyanine and used to produce thin solid films by means of the spin coating technique. The chemical structure of the spin coated films has been investigated by FT-IR analysis. Atomic Force Microscopy (AFM) has been used to characterize the film morphology and to measure the film thickness. The spin coated films have been tested as optical sensing materials of volatile organic compounds such as methanol, ethanol and 2-propanol. The change of optical reflectance of the films upon exposure to alcohol-vapour-containing atmospheres has been measured versus alcohol concentration and exposure time. The films exhibit a fast and reproducible response, with a complete and fast recovery in methanol and ethanol-containing atmospheres, while diffusion-driven effects appear during exposure to 2-propanol. The response and sensitivity of the films to ethanol vapour is higher than to methanol and 2-propanol.

Severova, Katerina; Maggioni, Gianluigi; Nespurek, Stanislav; Carturan, Sara; Milan, Riccardo; Tonezzer, Michele; Della Mea, Gianantonio

2007-06-01

47

Therapeutic uses of antioxidant liposomes.  

PubMed

This review will focus on the therapeutic uses of antioxidant liposomes. Antioxidant liposomes have a unique ability to deliver both lipid- and water-soluble antioxidants to tissues. This review will detail the varieties of antioxidants which have been incorporated into liposomes, their modes of administration, and the clinical conditions in which antioxidant liposomes could play an important therapeutic role. Antioxidant liposomes should be particularly useful for treating diseases or conditions in which oxidative stress plays a significant pathophysiological role because this technology has been shown to suppress oxidative stress. These diseases and conditions include cancer, trauma, irradiation, retinotherapy or prematurity, respiratory distress syndrome, chemical weapon exposure, and pulmonary infections. PMID:15247495

Stone, William L; Smith, Milton

2004-07-01

48

Electron transport and tunnelling spectroscopy in alkali doped metal phthalocyanines  

Microsoft Academic Search

We discuss electrical transport measurements performed on thin films of four different metal phthalocyanines doped with Potassium atoms. The temperature dependence of the conductivity shows that a metallic state occurs on a wide range of doping concentrations for all the four molecules. The occurence of the metallic state is confirmed by scanning tunneling spectroscopy. Key words. Metal phthalocyanine band filling

M. F. Craciun; S. Rogge; M. J. L. den Boer; T. M. Klapwijk; A. F. Morpurgo

2004-01-01

49

Characterization of Metal Phthalocyanine Catalysts Using Field Desorption Mass Spectrometry  

Microsoft Academic Search

Metal phthalocyanines are a very important class of compounds due to their ability to activate oxygen, which enables them to become useful chemical reagents and largely-accepted catalysts for many chemical reactions. Phthalocyanines containing metals like iron, cobalt, manganese and vanadium are useful catalysts in many refinery processes. In the petroleum industry mercaptans are oxidized to disulfides by aerobic oxidation in

V. Sugumaran; V. Kagdiyal; R. Kumar; R. Sarin; A. K. Gupta; A. S. Sarpal; B. Basu

2012-01-01

50

Linking photo- and redoxactive phthalocyanines covalently to graphene.  

PubMed

"Green" graphene: For the first time, the covalent attachment of a light-harvesting and electron-donating phthalocyanine to the basal plane of few-layer graphene is reported. Physicochemical characterizations reveal an ultrafast charge separation from the photoexcited phthalocyanine to few-layer graphene followed by a slower charge recombination. PMID:22593042

Ragoussi, Maria-Eleni; Malig, Jenny; Katsukis, Georgios; Butz, Benjamin; Spiecker, Erdmann; de la Torre, Gema; Torres, Tomás; Guldi, Dirk M

2012-05-16

51

Enhancement of ultrasonically induced cell damage by phthalocyanines in vitro  

Microsoft Academic Search

In this work, erythrocytes from carp were used as a nucleated cell model to test the hypothesis that the phthalocyanines (zinc – ZnPc and chloroaluminium –AlClPc) enhance ultrasonically induced damage in vitro. In order to confirm and complete our earlier investigation, the influence of ultrasound (US) and phthalocyanines (Pcs) on unresearched cellular components, was studied. Red blood cells were exposed

Katarzyna Milowska; Teresa Gabryelak

2008-01-01

52

The HVJ Liposome Method  

Microsoft Academic Search

Recent advancement of gene technology allows us a practical approach to gene therapy. Among various in vivo gene transfer techniques available, the HVJ liposome method is an efficient procedure which could target the glomerular cells. Using this method, HVJ-mediated cell fusion activity enables us to introduce genetic materials directly into the cytosol without degradation. In addition, cointroduction of non-histone nuclear

Yoshitaka Isaka; Yoshitaka Akagi; Yasufumi Kaneda; Enyu Imai

1998-01-01

53

The antimony(III)-bridged heteropolyanion sandwich dimers [Sb(II3(A-?-XW9O34)2]11- (X = SiIV, GeIV and C-shaped double-sandwich [SbIII6O2(PW6O26)(A-?-PW9O34)2]15-.  

PubMed

Interaction of potassium antimony(iii) tartrate hydrate K(2)(SbC(4)H(2)O(6))(2)·3H(2)O with the trilacunary Keggin derivatives [A-?-XW(9)O(34)](10-) (X = Si(IV), Ge(IV)) and [A-?-PW(9)O(34)](9-) in aqueous acidic medium (pH 4.8) resulted in three novel polyanions, [Sb(3)(A-?-XW(9)O(34))(2)](11-) (X = Si(IV) (1), Ge(IV) (2)) and [Sb(6)O(2)(A-PW(6)O(26))(A-?-PW(9)O(34))(2)](15-) (3), which were isolated as the hydrated potassium salts K(11)[Sb(3)(A-?-XW(9)O(34))(2)]·31H(2)O (X = Si(IV) (K-1), Ge(IV) (K-2)) and the mixed potassium-sodium salt K(14)Na[Sb(6)O(2)(A-PW(6)O(26))(A-?-PW(9)O(34))(2)]·61H(2)O (KNa-3) salts, respectively, and characterized by single-crystal X-ray diffraction, IR spectroscopy, as well as elemental and thermogravimetric analyses. The Sb(III)-containing polyanions 1-3 possess unique structural features, as they represent the first examples of sandwich-type POMs with trigonal-pyramidal Sb(III)O(3) linkers. The stability of 1-3 in aqueous media was investigated by multinuclear ((183)W, (31)P) NMR and UV-Vis spectroscopy. PMID:22543312

Assran, Awatef S; Izarova, Natalya V; Banerjee, Abhishek; Rabie, Usama M; Abou-El-Wafa, Moustafa H M; Kortz, Ulrich

2012-04-27

54

Novel axially disubstituted non-aggregated silicon phthalocyanines  

NASA Astrophysics Data System (ADS)

This paper describes the synthesis, spectroscopic characterization of a range of new axially-disubstituted silicon phthalocyanines with 2-[2-(dimethylamino)ethoxy] or 2-[2-(1,4,7,10,13-pentaoxa-16-azacyclooctadecan-16-yl)ethoxy] groups as axial ligands. 2-[2-(Dimethylamino)ethoxy]ethanol 2, 2-[2-(1,4,7,10,13-pentaoxa-16-azacyclooctadecan-16-yl)ethoxy]ethanol 4 are reacted with silicon phthalocyanine 1, to give an axially-disubstituted silicon phthalocyanines 3 and 5. Axially-disubstituted silicon phthalocyanine complexes were synthesized at the first time. Newly synthesized silicon phthalocyanines were characterized by UV-Vis, IR, 1H NMR, 13C NMR spectroscopy, ESI mass spectrometry. These new silicon(IV) phthalocyanines 3 and 5 showed excellent solubility in organic solvents such as CHCl3, CH2Cl2, acetone, DMF, DMSO, THF, EtOAc. The aggregation behavior of these compounds were investigated in different concentrations of DMSO. The effect of solvents on absorption spectra were studied in various organic solvents. The thermal stabilities of the silicon(IV) phthalocyanines 3 and 5 were determined by thermogravimetric analysis.

B?y?kl?o?lu, Zekeriya; Çak?r, Dilek

2012-12-01

55

Phthalocyanine-dyed fibers adsorb allergenic proteins.  

PubMed

Phthalocyanine (Pc)-dyed fiber is reported to reduce atopic symptoms in some patients when they use underwear made of the fiber. We investigated the adsorption of allergens on Pc-fiber. Pc-fiber trapped house dust/pollen/food allergens with varied molecular weight and pI. The adsorbed allergens were released in the presence of mild detergent. Pc-fiber did not change the molecular weight or disulfide bonding of the allergens. These observations imply that Pc-fiber is applicable as an "allergen trap" for a wide variety of products. PMID:16583306

Yano, H; Sugihara, Y; Shirai, H; Wagatsuma, Y; Kusada, O; Matsuda, T; Kuroda, S; Higaki, S

2006-04-04

56

Ciprofloxacin as ocular liposomal hydrogel.  

PubMed

The purpose of this study was to prepare and characterize an ocular effective prolonged-release liposomal hydrogel formulation containing ciprofloxacin. Reverse-phase evaporation was used for preparation of liposomes consisting of soybean phosphatidylcholine (PC) and cholesterol (CH). The effect of PC/CH molar ratio on the percentage drug encapsulation was investigated. The effect of additives such as stearylamine (SA) or dicetyl phosphate (DP) as positive and negative charge inducers, respectively, were studied. Morphology, mean size, encapsulation efficiency, and in vitro release of ciprofloxacin from liposomes were evaluated. For hydrogel preparation, Carbopol 940 was applied. In vitro transcorneal permeation through excised albino rabbit cornea was also determined. Optimal encapsulation efficiency of 73.04 +/- 3.06% was obtained from liposomes formulated with PC/CH at molar ratio of 5:3 and by increasing CH content above this limit, the encapsulation decreased. Positively charged liposomes showed superior entrapment efficiency (82.01 +/- 0.52) over the negatively charged and the neutral liposomes. Hydrogel containing liposomes with lipid content PC, CH, and SA in molar ratio 5:3:1, respectively, showed the best release and transcorneal permeation with the percentage permeation of 30.6%. These results suggest that the degree of encapsulation of ciprofloxacin into liposomes and prolonged in vitro release depend on composition of the vesicles. In addition, the polymer hydrogel used in preparation ensure steady and prolonged transcorneal permeation. In conclusion, ciprofloxacin liposomal hydrogel is a suitable delivery system for improving the ocular bioavailability of ciprofloxacin. PMID:20151337

Hosny, Khaled Mohamed

2010-02-12

57

Doxorubicin in sterically stabilized liposomes  

Microsoft Academic Search

Improved liposome stability and drug retention significantly increase the anticancer activity of encapsulated doxorubicin (Doxil), enhancing the effectiveness of chemotherapy and potentially reducing its toxicity.

Danilo D. Lasic

1996-01-01

58

The antioxidant properties of different phthalocyanines.  

PubMed

Oxidative stress is involved in the etiology of several chronic diseases, including cardiovascular disease, diabetes, cancer, and neurodegenerative disorders. From this perspective, we have evaluated the possible antioxidant capacities of five different phthalocyanines (PCs), consisting of four metallophthalocyanines (MPCs) and one simple phthalocyanine (PC) in order to explore, for the first time, the potential antioxidant activities of these compounds. Our results show that all PCs tested in this study have significant antioxidant activity in lipid peroxidation assay, providing protection from sodium nitroprusside -induced oxidative damage to supernatant from the homogenized liver, brain, e rim of mice. Compared to the non-induced control, the PCs were generally more efficient in reducing malondialdehyde levels in all assays on lipid peroxidation induced by sodium nitroprusside; the order of approximate decrease in efficiency was as follows: manganese-PC (better efficiency)>copper-PC>iron-PC>zinc-PC>PC (worst efficiency). Furthermore, the copper-PC and manganese-PC compounds exerted a significant protective effect in deoxyribose degradation assays, when employing Fe(2+), Fe(2+)+H(2)O(2), and H(2)O(2) solutions. In conclusion, all PCs tested here were shown to be promising compounds for future in vivo investigations, because of their potential antioxidant activities in vitro. PMID:22024102

Amaral, Guilherme Pires; Puntel, Gustavo Orione; Dalla Corte, Cristiane Lenz; Dobrachinski, Fernando; Barcelos, Rômulo Pillon; Bastos, Luiza Lena; Avila, Daiana Silva; Rocha, João Batista Teixeira; da Silva, Edegar Ozorio; Puntel, Robson Luiz; Soares, Félix Alexandre Antunes

2011-10-17

59

A Remote Controlled Valve in Liposomes for Triggered Liposomal Release  

Microsoft Academic Search

In order to reduce the toxicity and increase the efficacy of drugs, there is a need for smart drug delivery systems. Liposomes are one of the promising tools for this purpose. An ideal liposomal delivery system should be stable, long-circulating, accumulate at the target site and release its drug in a controlled manner. Even though there have been many developments

Arma?an Koçer

2007-01-01

60

Detailed hyperfine structure of muoniated radicals in planar phthalocyanines  

NASA Astrophysics Data System (ADS)

A detailed report of the hyperfine structure of paramagnetic muoniated radicals in the planar phthalocyanine zinc phthalocyanine (ZnPc) is given in this work. The hyperfine parameters of the three muoniated radical states formed in this compound were determined from high transverse-field ?SR measurements of a polycrystalline sample, taking into account the axial symmetry of the hyperfine tensor. States I and II are seen to possess a small dipolar character, consistent with the delocalization of the radical's electron to the inner ring of the phthalocyanine molecule, while state III has a hyperfine structure similar to the MuBC centre formed in inorganic semiconductors. This suggests that the muon in state III occupies an interstitial position between two stacked phthalocyanine molecules.

Piroto Duarte, J.; Vilão, R. C.; Alberto, H. V.; Gil, J. M.; Weidinger, A.; Ayres de Campos, N.

2009-04-01

61

Liposome: classification, preparation, and applications  

NASA Astrophysics Data System (ADS)

Liposomes, sphere-shaped vesicles consisting of one or more phospholipid bilayers, were first described in the mid-60s. Today, they are a very useful reproduction, reagent, and tool in various scientific disciplines, including mathematics and theoretical physics, biophysics, chemistry, colloid science, biochemistry, and biology. Since then, liposomes have made their way to the market. Among several talented new drug delivery systems, liposomes characterize an advanced technology to deliver active molecules to the site of action, and at present, several formulations are in clinical use. Research on liposome technology has progressed from conventional vesicles to `second-generation liposomes', in which long-circulating liposomes are obtained by modulating the lipid composition, size, and charge of the vesicle. Liposomes with modified surfaces have also been developed using several molecules, such as glycolipids or sialic acid. This paper summarizes exclusively scalable techniques and focuses on strengths, respectively, limitations in respect to industrial applicability and regulatory requirements concerning liposomal drug formulations based on FDA and EMEA documents.

Akbarzadeh, Abolfazl; Rezaei-Sadabady, Rogaie; Davaran, Soodabeh; Joo, Sang Woo; Zarghami, Nosratollah; Hanifehpour, Younes; Samiei, Mohammad; Kouhi, Mohammad; Nejati-Koshki, Kazem

2013-02-01

62

Phthalocyanine-assisted photodynamic inactivation of pathogenic microorganisms  

Microsoft Academic Search

The phthalocyanine zinc(II) and aluminum (III) complexes were studied to photoinactivate the bacterial strains, Staphylococcus aureus, methacillin-sensitive and methacillin-resistant, Pseudomonas aeruginosa and one yeast Candida albicans. The binding of phthalocyanines to bacteria and fungi cells was evaluated by the means of laserinduced fluorescence technique. The fluorescent spectra of dyes (650 - 800 nm) after direct excitation (635 nm) were measured

Vanya Mantareva; Ivan Angelov; Ekaterina Borissova; Latchezar Avramov; Vesselin Kussovski

2007-01-01

63

Enhancement of ultrasonically induced cell damage by phthalocyanines in vitro.  

PubMed

In this work, erythrocytes from carp were used as a nucleated cell model to test the hypothesis that the phthalocyanines (zinc--ZnPc and chloroaluminium -AlClPc) enhance ultrasonically induced damage in vitro. In order to confirm and complete our earlier investigation, the influence of ultrasound (US) and phthalocyanines (Pcs) on unresearched cellular components, was studied. Red blood cells were exposed to 1 MHz continuous ultrasound wave (0.61 and/or 2.44 W/cm(2)) in the presence or absence of phthalocyanines (3 microM). To identify target cell damage, we studied hemolysis, membrane fluidity and morphology of erythrocytes. To demonstrate the changes in the fluidity of plasma membrane we used the spectrofluorimetric methods using two fluorescence probes: 1-[4-(trimethylamino)phenyl]-6-phenyl-1,3,5,-hexatriene (TMA-DPH) and 1,6-diphenyl-1,3,5-hexatriene (DPH). The effect of US and Pcs on nucleated erythrocytes morphology was estimated on the basis of microscopic observation. The enhancement of ultrasonically induced membrane damage by both phthalocyanines was observed in case of hemolysis, and membrane surface fluidity, in comparison to ultrasound. The authors also observed changes in the morphology of erythrocytes. The obtained results support the hypothesis that the Pcs enhance ultrasonically induced cell damage in vitro. Furthermore, the influence of ultrasound on phthalocyanines (Pcs) in medium and in cells was tested. The authors observed changes in the phthalocyanines absorption spectra in the medium and the increase in the intensity of phthalocyanines fluorescence in the cells. These data can suggest changes in the structure of phthalocyanines after ultrasound action. PMID:18495194

Milowska, Katarzyna; Gabryelak, Teresa

2008-04-12

64

Synthesis and characterization of di-disubstituted phthalocyanines  

Microsoft Academic Search

An improved approach to the synthesis of di-disubstituted phthalocyanines from two different phthalyl precursors is described. The method combines substituted 1,3 diiminoisoindoles and 6\\/7-nitro-1,3,3-trichloroisoindolenine to synthesize phthalocyanine. The method can be applied to the synthesis of hydrogen and metallo phtahlocyanine. The yields are variable, ranging from 17% to 72% depending on the substituents.

Joseph G. Young; William Onyebuagu

1990-01-01

65

Liposomes in drug delivery: Progress and limitations  

Microsoft Academic Search

Liposomes are microparticulate lipoidal vesicles which are under extensive investigation as drug carriers for improving the delivery of therapeutic agents. Due to new developments in liposome technology, several liposome- based drug formulations are currently in clinical trial, and recently some of them have been approved for clinical use. Reformulation of drugs in liposomes has provided an opportunity to enhance the

Amarnath Sharma; Uma S. Sharma

1997-01-01

66

Propulsion of liposomes using bacterial motors  

NASA Astrophysics Data System (ADS)

Here we describe the utilization of flagellated bacteria as actuators to propel spherical liposomes by attaching bacteria to the liposome surface. Bacteria were stably attached to liposomes using a cross-linking antibody. The effect of the number of attached bacteria on propulsion speed was experimentally determined. The effects of bacterial propulsion on the bacteria-antibody-liposome complex were stochastic. We demonstrated that liposomal mobility increased when bacteria were attached, and the propulsion speed correlated with the number of bacteria.

Zhang, Zhenhai; Li, Zhifei; Yu, Wei; Li, Kejie; Xie, Zhihong; Shi, Zhiguo

2013-05-01

67

Synchrotron Studies on Copper-Phthalocyanine  

NASA Astrophysics Data System (ADS)

Studies were carried out using synchrotron radiation to investigate the properties of Copper-Phthalocyanine (CuPc) on different substrates. CuPc's have a wide variety of applications from dye to chemical sensors. This study was done at Lawrence Livermore National Laboratory in conjunction with UC San Diego to investigate properties of CuPc's for application in sensors. Near edge x-ray fine structure spectroscopy (NEXAFS) was used to determine orientations of CuPc molecules on two different substrates (gold and sapphire). Orientations were found to be drastically different on the two substrates. On gold, CuPc molecules were found to be nearly prostrate and on sapphire they were found to be almost normal to the surface.

Call, Robert; Willey, Trevor

2009-10-01

68

Vibrational studies of molecular organization in evaporated phthalocyanine thin solid films  

SciTech Connect

This report presents results on the study of the molecular organization, utilizing transmission and reflection absorption FTIR spectroscopy, of thin films of phthalocyanine complexes and metal free phthalocyanine. The spatial anisotropy was probed.

Aroca, R.; Thedchanamoorthy, A. [Univ. of Windsor (Canada)

1995-01-01

69

Optical properties and recording characteristics of phthalocyanine-derivative LB films  

NASA Astrophysics Data System (ADS)

Langmuir-Blodgett (LB) films of tetra-neopentoxy phthalocyanine zinc and tetra-nonyl phthalocyanine copper are prepared. Their structures, optical properties, and temperature dependencies are investigated. Static optical recording tests by He-Ne laser are done in these LB films and the experimental results demonstrate that phthalocyanine derivates are useful for phase change type erasable data storage media.

Gan, Fuxi; Luo, Tao

1993-08-01

70

Stimulated Emission Observed from an Organic Dye, Chloro-aluminum Phthalocyanine  

Microsoft Academic Search

We have observed that when a specific phthalocyanine solution (chloro-aluminum phthalocyanine dissolved in ethyl alcohol) is irradiated by a sufficiently powerful beam from a giant-pulse ruby laser, there occurs intense stimu- lated emission from the phthalocyanine molecules. The wavelength of this stimulated emission is centered at approximately 0.755 p. Its spectral half-width was observed

P. P. Sorokin; J. R. Lankard

1966-01-01

71

Photodynamic pathogen inactivation in red cell concentrates with the silicon phthalocyanine Pc 4  

NASA Astrophysics Data System (ADS)

The silicon phthalocyanine Pc 4, a photosensitizer activated with red light, has been studied for pathogen inactivation in red blood cell concentrates (RBCC). Pc 4 targets the envelope of pathogenic viruses such as HIV. To protect RBC during the process two main approaches are used: 1) Inclusion of quenches of reactive oxygen species produced during treatment. Tocopherol succinate was found to be most effective for this purpose. 2) Formulation of Pc 4, a lipophilic compound, in liposomes that reduce its binding to RBC but not to viruses. As a light source we used a light emitting diode array emitting at 660-680 nm. An efficient mixing device ensures homogeneous light exposure during treatment of intact RBCC. Treatment of RBCC with 5 (mu) M Pc 4 a d light results in the inactivation of >= 5.5 log10 HIV, >= 6.6 log10 VSV, and >= 5 log10 of PRV and BVDV. Parasites that can be transmitted by blood transfusion are even more sensitive than viruses. Following treatment, RBCC can be stored for 28 days at 4 degrees C with hemolysis below 1 percent. Baboon RBC circulate with an acceptable 24 hour recovery and half-life. Genetic toxicological studies of Pc 4 with or without light exposure are negative. We conclude that a process using Pc 4 and red light can potentially reduce the risk of transmitting pathogens in RBCC used for transfusion.

Ben-Hur, Ehud; Chan, Wai-Shun; Yim, Zachary; Zuk, Maria M.; Dayal, Vinay; Roth, Nathan; Heldman, Eli; Lazlo, A.; Valeri, C. R.; Horowitz, Bernard

2000-03-01

72

Topical photodynamic therapy using transfersomal aluminum phthalocyanine tetrasulfonate: in vitro and in vivo study.  

PubMed

The efficacy of transfersomes (flexible liposomes) as a novel technique for topical delivery of the hydrophilic tetra-anionic photodynamic sensitizer aluminum (III) phthalocyanine tetrasulfonate (AlPcS4) was investigated, on mammalian fibroblasts and on Balb/c mice dorsal skin. AlPcS4 was loaded in transfersomes composed of phosphatidylcholine/sodium deoxycholate (5:1, 10:1, and 15:1?w/w, ratios), resulting in 110-, 160-, and 200-nm mean size vesicles with encapsulation efficiencies of 16, 25, and 30 %, respectively. In vitro studies on baby hamster kidney-21 fibroblasts revealed twofold enhancement of the photocytotoxicity of AlPcS4 loaded in transfersomes (Trans-AlPcS4), compared to free AlPcS4 dissolved in culture medium. The photocytotoxicity of Trans-AlPcS4 was less dependent on the incubation time with cells, compared to free AlPcS4. Topical application on the dorsal skin of Balb/c mice revealed that both free AlPcS4 and Trans-AlPcS4 exhibited evident photosensitization towards mice skin, but acquiring different regions of skin. PMID:23291878

Kassab, Kawser; El Fadeel, Doaa Abd; Fadel, Maha

2013-01-05

73

Liposome encapsulation of chelating agents  

DOEpatents

A method for transferring a chelating agent across a cellular membrane by encapsulating the charged chelating agent within liposomes and carrying the liposome-encapsulated chelating agent to the cellular membrane where the liposomes containing the chelating agent will be taken up by the cells, thereby transferring the chelating agent across the cellular membrane. A chelating agent can be introduced into the interior of a cell of a living organism wherein the liposomes will be decomposed, releasing the chelating agent to the interior of the cell. The released chelating agent will complex intracellularly deposited toxic heavy metals, permitting the more soluble metal complex to transfer across the cellular membrane from the cell and subsequently be removed from the living organism.

Rahman, Yueh Erh (Downers Grove, IL)

1976-01-13

74

Layer formations of DPPC liposomes  

NASA Astrophysics Data System (ADS)

Liposomes (multilamellar vesicles) are formed with concentric onion-like shells of alternating water and lipid-bilayer regions. These structures are characterised by the parameters of the periodical shells. Centrosymmetrical shell model was used to describe the measured small-angle neutron scattering curves of the L?'(gel) and P?'(rippled gel) phases of dipalmitoylphosphatidylcholine (DPPC) liposomes applying Gaussian thickness fluctuations in the radial periodicity.

Drucker, T.; Bóta, A.; Borbély, S.

2000-03-01

75

Photophysical properties of dendrimer phthalocyanine-functionalized single-walled carbon nanotubes  

NASA Astrophysics Data System (ADS)

The photophysical properties of a novel series dendrimer phthalocyanine-SWNTs nanoconjugates in which the dendrimer phthalocyanine was tetra-[3,5-di-(4-carboxylic benzyloxy)benzyloxy] zinc(?) phthalocyanine covalently linked with SWNTs using ethylenediamine or hexamethylenediamine as space linkers were investigated in detailed by the fluorescent spectra and time-resolved spectroscopy. The photoindued intramolecular electron was transferred from phthalocyanine (donor) to carbon nanotubes (acceptor). Novel functionalized constituents in this work are fundamentally important due to the synergy effects of carbon nanotubes and dendritic zinc phthalocyanine, which may find potential applications in the drug delivery, biological labels and many other related fields.

Yang, Hongqin; He, Dandan; Peng, Yiru; Ma, Dongdong; Wang, Yuhua

2012-11-01

76

Magnetic-field-induced enhancement of crystallinity and field-effect mobilities in phthalocyanine thin films  

NASA Astrophysics Data System (ADS)

Organic semiconductor thin films were fabricated by thermal deposition of free-base and metal phthalocyanines under a static magnetic field. A vertical magnetic field enhanced the crystallinity of the edge-on orientation of the phthalocyanine discs, whereas a horizontal magnetic field had a minimal effect on the crystallinity. The major factor for the orientation change is attributed to the diamagnetic anisotropies of ?-electrons in the phthalocyanine macrocycles. Field-effect transistors of phthalocyanine films fabricated under a vertical magnetic field exhibited better hole mobilities and on-current values with smaller threshold voltages than those of phthalocyanine films fabricated without a magnetic field.

Tabata, Kenichi; Sasaki, Takayuki; Yamamoto, Yohei

2013-07-01

77

Enhanced ferromagnetism by adding electrons in triple-decker Gd-phthalocyanine  

NASA Astrophysics Data System (ADS)

The electronic structures and magnetic properties of triple-decker Gd-phthalocyanine have been studied by using the HSE06 hybrid function method. The results show that triple-decker Gd-phthalocyanine is a small band gap semiconductor. Ferromagnetic coupling is unstable in neutral triple-decker Gd-phthalocyanine due to the small energy difference between the ferromagnetic and antiferromagnetic state. Additional electrons can enhance the energy difference; the largest for triple-decker Gd-phthalocyanine is 0.062 eV with two additional electrons per phthalocyanine ring. A larger energy difference can result in stable ferromagnetic coupling in triple-decker Gd-phthalocyanine. Analysis of the wave function distribution and electron density difference shows that the additional electrons will occupy the innermost conjugate ring. The innermost conjugate ring is filled by the additional two electrons per phthalocyanine ring. The more electrons that occupy the innermost conjugate ring, the more enhanced the pz-f exchange interaction is, which is the reason for the ferromagnetic coupling in triple-decker Gd-phthalocyanine. Thus, the ferromagnetic coupling of triple-decker Gd-phthalocyanine with two additional electrons per phthalocyanine ring is the most stable. The ferromagnetism of triple-decker Gd-phthalocyanine that is enhanced by the additional electrons has potential applications in organic spintronics.

Tang, Zhen-kun; Wang, Ling-Ling; Zhang, Deng-Yu; Xu, Liang; Li, Xiao-Fei; Huang, Wei-Qing

2013-04-01

78

Sequential biphotonic processes: photochemical reactivity of phthalocyanine radicals  

SciTech Connect

Results of a study of the photochemistry of Rh(III), Al(III), and Zn(II) phthalocyanine cation radicals are reported here. The radicals were generated in a flash photolysis apparatus, which employs two flash-lamp-pump dye lasers. This excitation of the metallophthalocyanines at wavelengths of the phthalocyanine's Q band produced the long-lived triplet state. Irradiation of the phthalocyanine radicals led to rapid (t less than 1 ..mu..s) decomposition of these species followed by a partial recovery of the radical concentration. The dependence of radical yield on medium conditions was noted, and this dependence was probably attributable to an increase in the yield of the reactive excited state and/or a decrease in the rate of excited-state relaxation in changing from protic to aprotic media or replacing D/sub 2/O by H/sub 2/O. 10 references, 3 figures, 2 tables.

Van Vlierberge, B.; Ferraudi, G.

1987-01-28

79

Carbon dioxide reduction at a metal phthalocyanine catalyzed carbon electrode  

SciTech Connect

Metal phthalocyanines (metal = Co, Ni) deposited on carbon electrodes have been found to catalyze the electroreduction of carbon dioxide to formic acid in acid solutions (pH = 3-7). The overpotential for CO/sub 2/ reduction on cobalt phthalocyanine is approximately 200 mV lower than on the best metal cathodes at currents up to 10 mA/cm/sup 2/. The main reaction product in long-term electrolysis is the formate ion at pH>5. Methanol is also produced at lower pH values. The phthalocyanine becomes inactive in the less acid solutions once a fairly negative potential is imposed, probably due to an irreversible reduction of the catalyst.

Kapusta, S.; Hackerman, N.

1984-07-01

80

Excited state dynamics of phthalocyanine films  

SciTech Connect

Femtosecond pump-probe transient absorption measurements were performed for thermally evaporated polycrystalline vanadyl and lead phthalocyanine (VOPc and PbPc) films in order to obtain information about the excitation energy migration and relaxation. The films were shown to be composed of phase II and amorphous material. Fast excitation localization in phase II was concluded from measurement and analysis of the ground and excited state spectra. Comparison of the ground state, difference absorption, and luminescence spectra suggests a small oscillator strength of the electronic transition from the lowest excited state to the ground state. The influence of local heating on the transient spectra is discussed, and the possibility to obtain the excitation decay kinetics free from this influence is proposed. Exciton-exciton annihilation with a time dependent rate (proportional to t{sup -0.5}) is observed in both films. This is explained by one-dimensional diffusion-limited annihilation. Linear relaxation times are equal to 28{+-}6 and 42{+-}8 ps and approximate intermolecular excitation hopping times of 0.1 divide 0.4 and 0.02 divide 0.08 ps were determined for VOPc and PbPc, respectively. 22 refs., 8 figs., 1 tab.

Gulbians, V.; Valkunas, L. [Vilnius Inst. of Physics (Lithuania); Chachisvillis, M.; Sundstrom, V. [Lund Univ. (Sweden)

1996-02-08

81

Asymmetric grain distribution in phthalocyanine thin films  

SciTech Connect

Many electronic and optical properties of organic thin films depend on the precise morphology of grains. Iron phthalocyanine thin films are grown on sapphire substrates at different temperatures to study the effect of grain growth kinematics and to experimentally quantify the grain size distribution in organic thin films. The grain size is measured with an atomic force microscope and the data is processed and analyzed with well-known image segmentation algorithms. For relevant statistics, over 3000 grains are evaluated for each sample. The data show pronounced asymmetric grain growth with increasing deposition temperature from almost spherical grains at room temperature to elongated needlelike shapes at 260 deg. C. The average size along the major axis increases from 35 to 200 nm and along the minor axis from 25 to 90 nm. The distribution is almost symmetric at low-deposition temperatures, but becomes lognormal at higher temperatures. Strikingly, the major axis and minor axis of the elliptically shaped grains have different distributions at all temperatures due to the planar asymmetry of the molecule.

Gentry, K. Paul; Gredig, Thomas; Schuller, Ivan K. [Department of Physics and Astronomy, California State University-Long Beach, 1250 Bellflower Boulevard, Long Beach, California 90840 (United States); Department of Physics and Astronomy, University of California-San Diego, 9500 Gilman Drive, La Jolla, California 92093 (United States)

2009-11-01

82

Azide-Reactive Liposome for Chemoselective and Biocompatible Liposomal Surface Functionalization and Glyco-Liposomal Microarray Fabrication  

PubMed Central

A chemically selective liposomal surface functionalization and liposomal microarray fabrication using azide-reactive liposome are described. First, liposome carrying PEG-triphenylphosphine was prepared for Staudinger ligation with azide-containing biotin, which was conducted in PBS buffer (pH 7.4) at room temperature without catalyst. Then, immobilization and microarray fabrication of the biotinylated liposome onto streptavidin-modified glass slide via specific streptavidin/biotin interaction were investigated by comparing with direct-formed biotin-liposome, which was prepared by conventional liposome formulation of lipid-biotin with all other lipid components. Next, covalent microarray fabrication of liposome carrying triphenylphosphine onto an azide-modified glass slide and its further glyco-modification with azide-containing carbohydrate were demonstrated for glyco-liposomal microarray fabrication via Staudinger ligation. Fluorescence imaging confirmed the successful immobilization and protein binding of the intact immobilized liposomes and arrayed glyco-liposomes. The azide-reactive liposome provides a facile strategy for a membrane-mimetic glycoarray fabrication, which may find important biological and biomedical applications such as studying carbohydrate-protein interaction and toxin and antibody screening.

Ma, Yong; Zhang, Hailong; Gruzdys, Valentinas; Sun, Xue-Long

2011-01-01

83

Azide-reactive liposome for chemoselective and biocompatible liposomal surface functionalization and glyco-liposomal microarray fabrication.  

PubMed

Chemically selective liposomal surface functionalization and liposomal microarray fabrication using azide-reactive liposomes are described. First, liposome carrying PEG-triphenylphosphine was prepared for Staudinger ligation with azide-containing biotin, which was conducted in PBS buffer (pH 7.4) at room temperature without a catalyst. Then, immobilization and microarray fabrication of the biotinylated liposome onto a streptavidin-modified glass slide via the specific streptavidin/biotin interaction were investigated by comparing with directly formed biotin-liposome, which was prepared by the conventional liposome formulation of lipid-biotin with all other lipid components. Next, the covalent microarray fabrication of liposome carrying triphenylphosphine onto an azide-modified glass slide and its further glyco-modification with azide-containing carbohydrate were demonstrated for glyco-liposomal microarray fabrication via Staudinger ligation. Fluorescence imaging confirmed the successful immobilization and protein binding of the intact immobilized liposomes and arrayed glyco-liposomes. The azide-reactive liposome provides a facile strategy for membrane-mimetic glyco-array fabrication, which may find important biological and biomedical applications such as studying carbohydrate-protein interactions and toxin and antibody screening. PMID:21928859

Ma, Yong; Zhang, Hailong; Gruzdys, Valentinas; Sun, Xue-Long

2011-10-07

84

Liposome-Encapsulated Actinomycin for Cancer Chemotherapy.  

National Technical Information Service (NTIS)

An improved method is provided for chemotherapy of malignant tumors by injection of antitumor drugs. The antitumor drug is encapsulated within liposomes and the liposomes containing the encapsulated drug are injected into the body. The encapsulated drug p...

Y. E. Rahman E. A. Cerny

1976-01-01

85

Catalytic oxidation of sulfur dioxide by heterogeneous cobalt-phthalocyanine  

SciTech Connect

Various homogeneous and hybrid cobalt phthalocyanines were developed. They were shown to be effective catalysts for the catalytic degradation of many aqueous pollutants. The catalytic activity of these systems was attributed to their ability to activate molecular oxygen. Semiconductor titanium dioxide was found to be useful both as solid support and photocatalyst. The electron relay property of cobalt phthalocyanine on the photoactive TiO/sub 2/ surface was elucidated. The homogeneous and heterogeneous kinetics and mechanisms for the catalytic oxidation of aqueous sulfur dioxide were studied.

Hong, P.K.A.

1988-01-01

86

Copper phthalocyanine bonding with gel and their optical properties  

Microsoft Academic Search

(Tetracarboxyphalocyaninato)copper(II), (CuPc(COOH)4) is incorporated in gel by a sol–gel process with using 3-aminopropyltriethoxysilane (NH2(CH2)3Si(OC2H5)3, APTS) and 3-glycidoxypropl-trimethoxysilane (CH2OCHCH2O(CH2)3Si(OCH3)3, GPTMS) as precursors. The starting compound and the gel are in the dimer forms of copper phthalocyanine, which are identified from their UV\\/visible spectra. The aggregation of copper phthalocyanine dyes from sol to gel is effectively prevented by tethering them to sol–gel

Haiping Xia; Masayuki Nogami

2000-01-01

87

Mechanical detection of liposomes using piezoresistive cantilever  

Microsoft Academic Search

This paper firstly reports the mechanical and real-time detection of liposomes using the highly sensitive microfabricated piezoresistive cantilever sensor chip and liposome–protein interaction. The cantilevers were functionalized with the chemically modified protein C2A which recognizes the phosphatidylserine (PS) exposed on the surface of liposome. The attachment of liposome induced the bending motion of the piezoresistive cantilever and consequently generated the

Seok-Jung Hyun; Hyun-Seok Kim; Yong-Jun Kim; Hyo-Il Jung

2006-01-01

88

The Role of Cavitation in Liposome Formation  

Microsoft Academic Search

Liposome size is a vital parameter of many quantitative biophysical studies. Sonication, or exposure to ultrasound, is used widely to manufacture artificial liposomes, yet little is known about the mechanism by which liposomes are affected by ultrasound. Cavitation, or the oscillation of small gas bubbles in a pressure-varying field, has been shown to be responsible for many biophysical effects of

Eric S. Richardson; William G. Pitt; Dixon J. Woodbury

2007-01-01

89

Weak epitaxy growth and phase behavior of planar phthalocyanines on p-sexiphenyl monolayer film.  

PubMed

We systematically investigated the weak epitaxy growth (WEG) behavior of a series of planar phthalocyanine compounds (MPc), i.e., metal-free phthalocyanine (H2Pc), nickel phthalocyanine (NiPc), copper phthalocyanine (CuPc), zinc phthalocyanine (ZnPc), iron phthalocyanine (FePc), cobalt phthalocyanine (CoPc), grown on a p-sexiphenyl ( p-6P) monolayer film by selected area electron diffraction (SAED) and atomic force microscopy (AFM). Two types of epitaxial relations, named as incommensurate epitaxy and commensurate epitaxy, were identified between phthalocyanine compounds and the substrate of the p-6P film. The tiny variation of the lattice constant of phthalocyanine compounds can result in different crystal orientations. The change rule of incommensurate and commensurate epitaxy was extracted. The tendency of commensurate epitaxy becomes weaker as the lattice constant b increases, while it gets stronger as the substrate temperature is elevated. Large size and continuous H2Pc films can be obtained by controlling the growth conditions. The WEG method is generally applicable in the whole family of planar phthalocyanine compounds and may be used to fabricate other high-quality organic films. PMID:18461987

Wang, Tong; Yang, Junliang; Wang, Haibo; Zhu, Feng; Yan, Donghang

2008-05-08

90

Liposomes for cryopreservation of bovine sperm.  

PubMed

In this study, the effect of various unilamellar liposomes on cryopreservation of bovine spermatozoa has been investigated. Liposomes were composed of saturated lipids with various acyl chain lengths: DSPC (18:0), DPPC (16:0), DMPC (14:0), or DLPC (12:0). Alternatively, liposomes were prepared using unsaturated egg phosphatidylcholine (EPC) or DOPC (18:1, neutral), alone or in combination with lipids with various head groups: DOPS (negatively charged), DOPG (negatively charged), and DOPE (neutral). Fourier transform infrared spectroscopy studies showed that bovine sperm membranes display a gradual phase transition from 10 to 24 (o)C. Phase transition temperatures of the liposomes varied from -20 to +53 (o)C. Sperm was incubated in the presence of liposomes for either 6 or 24 h at 4 °C prior to freezing. Postfreeze survival rates were determined based on the percentage of progressively motile cells as well as the percentage of acrosome- and plasma membrane-intact cells. With DOPC liposomes a postthaw progressive motility of 43% was obtained compared with 59% using standard egg yolk freezing extender. Postthaw progressive motility increased up to 52% using DOPC:DOPG (9:1) liposomes, whereas DOPC:DOPS or DOPC:DOPE liposomes did not increase survival compared with DOPC liposomes. Among the saturated lipids, only DMPC was found to increase cryosurvival, up to 44% based on progressive motility. DLPC liposomes caused a complete loss in cell viability, already prior to freezing, whereas DPPC and DSPC liposomes neither positively nor negatively affected cryosurvival. Taken together, the higher postthaw survival obtained with DOPC:DOPG liposomes as compared with DOPC liposomes can likely be attributed to increased liposome-sperm interactions between the charged phosphatidylglycerol groups and charged regions in the sperm membranes. Interestingly, the lipid phase state of the liposomes during preincubation is not the decisive factor for their cryoprotective action. PMID:21820724

Röpke, T; Oldenhof, H; Leiding, C; Sieme, H; Bollwein, H; Wolkers, W F

2011-08-06

91

Dynamics of phthalocyanine Al accumulation in stomach cancer photodynamic therapy  

NASA Astrophysics Data System (ADS)

Methods of stomach cancer photodynamic therapy with the use of Kr laser and photosensitizer-phthalocyanine (Al-Pc) are discussed. The level of preparation accumulation in the tumor and surrounding tissues has been investigated with the use of laser spectroanalyzer LESA-4 (`Biospec'). Dynamics of (Al-Pc) accumulation investigated depend on different types of tumors and different parameters of laser irradiation.

Kharnas, S. S.; Loschenov, Victor B.; Stratonnikov, A. A.; Kramarenko, T. A.; Artemjeva, O. V.; Bakonin, V. P.; Kuzin, M. I.; Zavodnov, V. Y.; Steiner, Rudolf W.

1995-01-01

92

Influence of copper-phthalocyanine on the photodegradation of polycarbonate  

Microsoft Academic Search

Dyes and pigments are extensively used in polymer materials to confer colour-changing properties. However, these additives can significantly affect polymer stability against degradation. While the mechanism of stabilization of polymers by some pigments, such as carbon black, has been studied and is well known, the action of chromatic colorants, mainly in the sensitization of the degradation process, remains unclear. Cu-phthalocyanine

Clodoaldo Saron; Fabio Zulli; Marco Giordano; Maria Isabel Felisberti

2006-01-01

93

Electronic Structure of and Bonding in Antimony Phthalocyanine Complex.  

National Technical Information Service (NTIS)

Although the elemental analysis of the product, antimony phthalocyanine, seems to fit for the formula PcSb2, it is difficult to figure out the possible structure for the formula by ordinary valency requirement of antimony. Crystalization from THF gave ris...

M. Tsutsui D. D. Axtell K. Tatsumi

1979-01-01

94

Capabilities of liposomes for topological transformation  

NASA Astrophysics Data System (ADS)

Dynamic behaviors of liposomes caused by interactions between liposomal membranes and surfactant were studied by direct real-time observation by using high-intensity dark-field microscopy. Solubilization of liposomes by surfactants is thought to be a catastrophic event akin to the explosion of soap bubbles in the air; however, the actual process has not been clarified. We studied this process experimentally and found that liposomes exposed to various surfactants exhibited unusual behavior, namely continuous shrinkage accompanied by intermittent quakes, release of encapsulated liposomes, opening up, and inside-out topological inversion.

Nomura, Fumimasa; Nagata, Miki; Inaba, Takehiko; Hiramatsu, Haruka; Hotani, Hirokazu; Takiguchi, Kingo

2001-02-01

95

Redox-Triggered Contents Release from Liposomes  

PubMed Central

An exciting new direction in responsive liposome research is endogenous triggering of liposomal payload release by overexpressed enzyme activity in affected tissues and offers the unique possibility of active and site-specific release. Bringing to fruition the fully expected capabilities of this new class of triggered liposomal delivery system requires a collection of liposome systems that respond to different upregulated enzymes; however, a relatively small number currently exist. Here we show that stable, ~100 nm diameter liposomes can be made from previously unreported quinone-dioleoyl phosphatidylethanolamine (Q-DOPE) lipids, and complete payload release (quenched fluorescent dye) from Q-DOPE liposomes occurs upon their redox activation when the quinone headgroup possesses specific substituents. The key component of the triggerable, contents-releasing Q-DOPE liposomes is a “trimethyl-locked” quinone redox switch attached to the N-terminus of DOPE lipids that undergoes a cleavage event upon two-electron reduction. Payload release by aggregation and leakage of “uncapped” Q-DOPE liposomes is supported by results from liposomes wherein deliberate alteration of the “trimethyl-locked” switch completely deactivates the redox-destructible phenomena (liposome opening). We expect that Q-DOPE liposomes and their variants will be important in treatment of diseases with associated tissues that overexpress quinone reductases, such as cancers and inflammatory diseases, because the quinone redox switch is a known substrate for this group of reductases.

Ong, Winston; Yang, Yuming; Cruciano, Angela C.; McCarley*, Robin L.

2008-01-01

96

Temperature-Sensitive Liposomal Formulation.  

National Technical Information Service (NTIS)

A liposome contains an active agent and has a gel-phase lipid bilayer membrane comprising phospholipid and a surface active agent. The phospholipids are the primary lipid source for the lipid bilayer membrane and the surface active agent is contained in t...

D. Needham

2005-01-01

97

Binding of daidzein to liposomes  

Microsoft Academic Search

Turbidity and differential scanning calorimetry measurements revealed the plant derived antineoplastic isoflavone, daidzein, to bind to large unilamellar liposomes. Comparing different unsaturated phospholipids most pronounced aggregation due to daidzein was observed for phosphatidylinositol (PI) while the inclusion of cholesterol strongly attenuated the aggregation. Interestingly, aggregation was not observed for the structurally very closely related isoflavone, genistein. The extent of aggregation

Jukka Y. A. Lehtonen; Herman Adlercreutz; Paavo K. J. Kinnunen

1996-01-01

98

Zinc oxide and metal phthalocyanine based hybrid P-N junction diodes  

NASA Astrophysics Data System (ADS)

Hybrid p-n junction diode based on zinc oxide (ZnO) and metal phthalocyanine (MePc) has been demonstrated using highly conducting Al doped ZnO as transparent electrode. Three different MePcs: copper phthalocyanine, zinc phthalocyanine (ZnPc), and cobalt phthalocyanine are used as p-type layer in hybrid p-n junction. It is found that most desirable performance can be achieved in ZnO/ZnPc based hybrid p-n junction. The depletion region in hybrid p-n junctions has been measured using current-voltage and capacitance-voltage characteristics.

Singh, Budhi; Ghosh, Subhasis

2013-09-01

99

Liposomal gels for vaginal drug delivery.  

PubMed

The aim of our study was to develop a liposomal drug carrier system, able to provide sustained and controlled release of appropriate drug for local vaginal therapy. To optimise the preparation of liposomes with regards to size and entrapment efficiency, liposomes containing calcein were prepared by five different methods. Two optimal liposomal preparations (proliposomes and polyol dilution liposomes) were tested for their in vitro stability in media that simulate human vaginal conditions (buffer, pH 4.5). To be closer to in vivo application of liposomes and to achieve further improvement of their stability, liposomes were incorporated in vehicles suitable for vaginal self-administration. Gels of polyacrylate were chosen as vehicles for liposomal preparations. Due to their hydrophilic nature and bioadhesive properties, it was possible to achieve an adequate pH value corresponding to physiological conditions as well as desirable viscosity. In vitro release studies of liposomes incorporated in these gels (Carbopol 974P NF or Carbopol 980 NF) confirmed their applicability as a novel drug carrier system in vaginal delivery. Regardless of the gel used, even 24 h after the incubation of liposomal gel in the buffer pH 4.5 more than 80% of the originally entrapped substance was still retained. PMID:11337174

Paveli?, Z; Skalko-Basnet, N; Schubert, R

2001-05-21

100

Essential oils encapsulated in liposomes: a review.  

PubMed

Abstract In the recent years there has been an increased interest toward the biological activities of essential oils. However, essential oils are unstable and susceptible to degradation in the presence of oxygen, light and temperature. So, attempts have been made to preserve them through encapsulation in various colloidal systems such as microcapsules, microspheres, nanoemulsions and liposomes. This review focuses specifically on encapsulation of essential oils into liposomes. First, we present the techniques used to prepare liposomes encapsulating essential oils. The effects of essential oils and other factors on liposome characteristics such as size, encapsulation efficiency and thermal behavior of lipid bilayers are then discussed. The composition of lipid vesicles membrane, especially the type of phospholipids, cholesterol content, the molar ratio of essential oils to lipids, the preparation method and the kind of essential oil may affect the liposome size and the encapsulation efficiency. Several essential oils can decrease the size of liposomes, homogenize the liposomal dispersions, increase the fluidity and reduce the oxidation of the lipid bilayer. Moreover, liposomes can protect the fluidity of essential oils and are stable at 4-5?°C for 6 months at least. The applications of liposomes incorporating essential oils are also summarized in this review. Liposomes encapsulating essential oils are promising agents that can be used to increase the anti-microbial activity of the essential oils, to study the effect of essential oils on cell membranes, and to provide alternative therapeutic agents to treat several diseases. PMID:23879218

Sherry, Mirna; Charcosset, Catherine; Fessi, Hatem; Greige-Gerges, Hélène

2013-07-24

101

Liposomal drug products and recent advances in the synthesis of supercritical fluid-mediated liposomes.  

PubMed

Since the pioneering research of Bangham et al. in 1965, liposomes have attracted a large amount of interest as potential carriers of various bioactive molecules for clinical applications. However, scaling-up conventional methods of liposome preparation has been proven to be challenging. Compared with conventional methods, processes that use supercritical fluid (SCF)-CO2 require a reduced amount of organic solvent, are relatively fast and simple to perform, and yield stable and more uniform liposomes. A number of studies have demonstrated that SCF-CO2 methods might be suitable for industrial-scale manufacturing of liposomes. In this review there are two topics being discussed. We provide an overview of liposomal drug products and aim to describe the physicochemical properties of liposomes prepared using various SCF methods. We review all of the available literature on SCF-CO2-based liposomes and focus on the future applications of these innovative technologies in industrial-scale liposome preparation. PMID:23987112

Karn, Pankaj Ranjan; Cho, Wonkyung; Hwang, Sung-Joo

2013-09-01

102

Fluticasone Propionate Liposomes for Pulmonary Delivery  

PubMed Central

The objective of the present study was to entrap fluticasone propionate in liposomes and study in vitro lung deposition of both liposomal dispersion and dry powder inhalation using twin stage impinger and Anderson cascade impactor. Liposomes were prepared by lipid film hydration method and characterized for size, shape, morphology, entrapment efficiency and in vitro lung deposition. The spray dried liposomes were further characterized for various physicochemical properties such as physical appearance, density, flow properties, drug content and in vitro pulmonary deposition. Fine particle fraction was also determined. Liposomal dispersion of fluticasone propionate was successfully prepared with more than 90% entrapment. Spray dried liposomes had mean size of 3-4 ? and a fine powder fraction of 9-10 %. Inclusion of antistatic agents such as leucine and magnesium stearate did not improve the aerosolisation behaviour of dry inhalation powder in this study.

Nirale, N. M.; Vidhate, R. D.; Nagarsenker, M. S.

2009-01-01

103

Enhanced laminin-derived peptide AG73-mediated liposomal gene transfer by bubble liposomes and ultrasound.  

PubMed

A promising strategy as a cancer therapeutic is tumor-targeted gene delivery. The AG73 peptide derived from the laminin alpha1 chain is a ligand for syndecans, and syndecan-2 is highly expressed in some cancer cells. In this study, AG73-PEG liposomes were developed for selective gene delivery to syndecan-2 overexpressing cancer cells. AG73-PEG liposomes were used in combination with Bubble liposomes and ultrasound exposure to enhance transfection efficiency by promoting the escape of the liposomes from the endosome to the cytosol. AG73-PEG liposomes showed selective gene delivery to syndecan-2 overexpressing cancer cells. Furthermore, AG73-mediated liposomal gene transfection efficiency was enhanced by 60-fold when Bubble liposomes and ultrasound exposure were used, despite the absence of an increase in the uptake of AG73-PEG liposomes into the cells. Confocal microscope analysis revealed that the Bubble liposomes and ultrasound promoted intracellular trafficking of the AG73-PEG liposomes during gene transfection. Thus, the combination of AG73-PEG liposomes with Bubble liposomes and ultrasound exposure may be a promising method to achieve selective and efficient gene delivery for cancer therapy. PMID:20020739

Negishi, Yoichi; Omata, Daiki; Iijima, Hiroshi; Takabayashi, Yasuko; Suzuki, Kentaro; Endo, Yoko; Suzuki, Ryo; Maruyama, Kazuo; Nomizu, Motoyoshi; Aramaki, Yukihiko

2010-02-01

104

Immobilization of liposomes onto quartz crystal microbalance to detect interaction between liposomes and proteins  

Microsoft Academic Search

To study the interaction between liposomes and proteins, intact liposomes were immobilized on a metal planar support by chemical binding and\\/or bioaffinity using a quartz crystal microbalance (QCM). A large decrease in the resonance frequency of quartz crystal was observed when the QCM, modified by a self-assembled monolayer (SAM) of carboxythiol, was added to liposome solutions. The stable chemical immobilization

Seiichi Morita; Miho Nukui; Ryoichi Kuboi

2006-01-01

105

Cobaltacarborane-phthalocyanine conjugates: Syntheses and photophysical properties  

PubMed Central

Syntheses of two new cobaltacarborane–phthalocyanine conjugates, one anionic (Pc 6) and one zwitterionic (Pc 7), were accomplished via cyclotetramerization of the corresponding cobaltacarborane-substituted phthalonitriles (4 or 5) with excess phthalonitrile in quinoline. X-ray structures of two phthalonitrile precursors (2 and 3) were obtained and are discussed, and the absorption and emission properties of the two cobaltacarborane–phthalocyanine conjugates in several solvents were investigated. The anionic conjugate 6 exists mainly as a monomer in polar organic solvents and has fluorescence quantum yields in the region 0.2–0.3. The zwitterionic conjugate 7 aggregates in solution and displays lower quantum yields ~0.1 in organic solvents.

Li, Hairong; Fronczek, Frank R.; Vicente, M. Graca H.

2010-01-01

106

Phthalocyanine photoelectrochemical cell prepared by a micelle disruption method  

SciTech Connect

Photoelectrochemical characteristics of a metal-free phthalocyanine electrode prepared by a micelle disruption method are described. The novel technique is found to provide more photoactive phthalocyanine layers on indium tin oxide (ITO), compared with a vacuum sublimation technique. A short-circuit photocurrent of 0.1 mA cm/sup -2/ is obtained for the ITO/H/sub 2/ Pc(MD)/I/sup -//sub 3/ -I/sup -//Pt cell under the white light illumination of 6 mW cm/sup -2/, together with an open-circuit photovoltage of 70 mV and a fill factor of 0.42. These data lead to a value of 0.06% for the energy conversion efficiency.

Harima, Y.; Yamashita, K.; Saji, T.

1988-05-02

107

Optical limiting behavior of octa-decyloxy metallo-phthalocyanines  

NASA Astrophysics Data System (ADS)

One of the key issues involved in the development of passive optical power limiters is the search for appropriate materials that show effective reverse saturable absorption. Metallo-phthalocyanines seem to be good candidates for such applications because of their high optical nonlinearity and their unique electronic absorption characteristics. A series of 1,4,8,11,15,18,22,25-octa-decyloxy metallo-phthalocyanines containing palladium, nickel, cobalt, copper, and zinc as central metal atoms were characterized for their nonlinear absorptive properties to evaluate their suitability to function as reverse saturable absorbers. Nonlinear transmission measurements were analyzed in terms of a five-state model and a simple model based on the effective excited-state absorption cross sections without ascribing their origin to the states involved. Optical limiting thresholds were also estimated and compared with the absorption cross sections.

Sanghadasa, Mohan; Shin, In-Seok; Clark, Ronald D.; Guo, Huaisong; Penn, Benjamin G.

2001-07-01

108

Interactions of hemoglobin with lecithin liposomes  

Microsoft Academic Search

In this paper, the interaction of hemoglobin (Hb) with lecithin liposomes is studied by UV-vis spectroscopy, fluorescent spectroscopy, and transmission electron microscopy. The adsorption of Hb on liposomes is likely to be related to the hydrophobic interaction between Hb and liposomes, which brings about the increase of the microenvironmental polarity (I\\u000a 1\\/I\\u000a 3) and the decrease of the fluorescence polarization

Juqun Xi; Rong Guo; Xia Guo

2006-01-01

109

Capabilities of liposomes for topological transformation  

Microsoft Academic Search

Dynamic behaviors of liposomes caused by interactions between liposomal membranes and surfactant were studied by direct real-time observation by using high-intensity dark-field microscopy. Solubilization of liposomes by surfactants is thought to be a catastrophic event akin to the explosion of soap bubbles in the air; however, the actual process has not been clarified. We studied this process experimentally and found

Fumimasa Nomura; Miki Nagata; Takehiko Inaba; Haruka Hiramatsu; Hirokazu Hotani; Kingo Takiguchi

2001-01-01

110

Selective non-covalent triggered release from liposomes.  

PubMed

A zinc(II)-dipicolylamine coordination complex selectively associates with anionic liposomes, including sterically protected PEGylated liposomes, and causes rapid leakage of encapsulated contents. PMID:22772732

Plaunt, Adam J; Courbanou, Meghan B; Cuison, Katrina D; Harmatys, Kara M; Smith, Bradley D

2012-07-09

111

Molecular Engineering of Zinc Phthalocyanines with Phosphinic Acid Anchoring Groups.  

PubMed

Zinc phthalocyanine sensitizers that contain phosphinic acid anchoring groups have an overall conversion efficiency of 3.24 % under 1 sun in a dye-sensitized solar cell (DSSC). M. K. Nazeeruddin, T. Torres, M. Grätzel, and co-workers demonstrate in their Communication (DOI: 10.1002/anie.201105950) that the phosphinic acid groups provide a stronger binding affinity relative to carboxylic acid anchoring groups, which improves the durability of DSSCs. PMID:22267269

López-Duarte, Ismael; Wang, Mingkui; Humphry-Baker, Robin; Ince, Mine; Martínez-Díaz, M Victoria; Nazeeruddin, Mohammad K; Torres, Tomás; Grätzel, Michael

2012-01-20

112

Investigation of the phase transition in different types of phthalocyanines  

Microsoft Academic Search

We have investigated the phase transition near room temperature and the behaviour in the low temperature phase in different samples of phthalocyanine (Pc). Our measured temperature dependence of the NMR proton-spin-lattice relaxation time T1 and of the lattice constants shows the existence of a phase transition. The dielectric measurements give a nonsaturated hysteresis loop due to the high a.c. conductivity

B. Dudreva; S. Grande

1974-01-01

113

Angle-dependent carrier injection in copper phthalocyanine thin films  

NASA Astrophysics Data System (ADS)

We present that the carrier concentration injected from a silicon substrate to a copper phthalocyanine thin film depends on the incidence angle of photoexciting beam. At higher incidence angles of photoexciting beam, the modulation efficiency of terahertz transmission due to TM-polarized excitation is distinctly higher than one due to TE-polarized excitation. We find that this phenomenon is due to the enhancement of carrier injection which is expected when the incident light is more transmitted through the organic thin film.

Yoo, Hyung Keun; Yoon, Youngwoon; Lee, Hanju; Lee, Kiejin; Kang, Chul; Kee, Chul-Sik; Lee, Joong Wook

2013-05-01

114

Comparison of lasers for photodynamic therapy with a phthalocyanine photosensitizer  

Microsoft Academic Search

Three different lasers were compared under the same conditions for their effectiveness at producing photodynamic damage to\\u000a normal colon following sensitization with aluminium sulphonated phthalocyanine (AlSPc). One laser was an argon ion pumped\\u000a continuous wave (CW) dye laser and the other two were pulsed at 10 kHz (copper vapour laser pumped dye laser, and 5 Hz (flashlamp\\u000a pumped dye laser).

H. Barr; P. B. Boulos; A. J. Macrobert; C. J. Tralau; D. Phillips; S. G. Bown

1989-01-01

115

Strong chemical interaction between indium tin oxide and phthalocyanines  

NASA Astrophysics Data System (ADS)

We present a study of the interface properties between indium tin oxide (ITO) and the well-established molecular organic semiconductor copper phthalocyanine (CuPC) and its fluorinated relative copper tetraflourophthalocyanine (CuPCF4) using photoemission spectroscopy. It is shown that a strong chemical interaction occurs between the PC molecules and ITO which indicates the presence of interface states at these technically relevant interfaces.

Peisert, H.; Knupfer, M.; Schwieger, T.; Fink, J.

2002-04-01

116

Tumor targeting using liposomal antineoplastic drugs  

PubMed Central

During the last years, liposomes (microparticulate phospholipid vesicles) have been used with growing success as pharmaceutical carriers for antineoplastic drugs. Fields of application include lipid-based formulations to enhance the solubility of poorly soluble antitumor drugs, the use of pegylated liposomes for passive targeting of solid tumors as well as vector-conjugated liposomal carriers for active targeting of tumor tissue. Such formulation and drug targeting strategies enhance the effectiveness of anticancer chemotherapy and reduce at the same time the risk of toxic side-effects. The present article reviews the principles of different liposomal technologies and discusses current trends in this field of research.

Huwyler, Jorg; Drewe, Jurgen; Krahenbuhl, Stephan

2008-01-01

117

Pegylated liposomal doxorubicin in ovarian cancer  

PubMed Central

Pegylated liposomal doxorubicin is a formulation of doxorubicin in which the molecule itself is packaged in a liposome made of various lipids with an outer coating of polyethylene glycol. Liposomal technology is being used in increasing amounts in the therapy of a variety of cancers, including ovarian cancers. This article reviews the mechanistic actions of this formulation, the Phase II and Phase III data that helped define the role of pegylated liposomal doxorubicin in recurrent ovarian cancer, as well as a discussion of some of the side-effects and their management.

Green, Andrew E; Rose, Peter G

2006-01-01

118

Interaction of phthalocyanine photodynamic treatment with ionophores and lysosomotrophic agents  

NASA Astrophysics Data System (ADS)

Phthalocyanines are receiving increasing attention as second-generation sensitizers for photodynamic therapy (PDT). This paper discusses some of the investigations into the mechanism of the phototoxic responses of phthalocyanine-sensitized PDT exploiting the interaction of PDT with other metabolic modulators. Among the agents which interact strongly with PDT is the K+/H+ ionophore nigericin. Under the conditions studied with chloroaluminum phthalocyanine (AlPcCl), the Na+/H+ ionophore monensin, the Ca++ ionophore A23187, and the lysosomotrophic agent chloroquine, but not the K+ ionophore valinomycin, also potentiate photodynamic cell killing. None of the latter compounds interact with PDT as strongly as does nigericin. Both nigericin and monensin partially inhibit cellular respiration; however, KCN, which inhibits respiration completely, is less effective in potentiating PDT damage than is nigericin. Nigericin treatment alone does not deplete glutathione; however, the GSH level decreases after treatment of cells with PDT and nigericin. The potentiation of the PDT response is much greater at an extracellular pH (pHe) of 6.70 than at pHe 7.30. When nigericin is present at pHe 6.70, the intracellular pH (pHi) is equilibrated with pHe. None of the other ionophores tested was able to cause the acidification of the intracellular milieu as did nigericin. The evidence to date suggests that the lowering of pHi is an important component of the mechanism by which nigericin potentiates PDT.

Oleinick, Nancy L.; Varnes, Marie E.; Clay, Marian E.; Menegay, Harry J.

1991-06-01

119

Localized orbital study on the electronic structure of phthalocyanine dimers  

SciTech Connect

The lowest excited state of lanthanide phthalocyanine dimer and {mu}-oxo silicon phthalocyanine dimer are studied by configuration interaction calculations on the localized orbital basis set obtained by a unitary transformation of semiempirical SCMOs of the dimers. The model can characterize the dimer excited states as a superposition of intraligand and interligand excitation. The higher energy component band in the Q band region of the lanthanide dimer complexes is ascribed to an excitation in the excited state essentially of the exciton coupling state, while the lower energy component band is assigned as an excitation to that of the charge resonance state, which is granted a spectral intensity from the exciton component. A rapid decrease in the splitting of the Q band of the dimers with increasing radius of the central lanthanide ion is attributable to a pronounced decrease in the difference of diagonal energies of charge transfer and local excitation configurations and the off-diagonal interaction between the two configurations. Theory can well reproduce the dimer spectra of Q band with a reduced interplanar two-electron interaction ({alpha} = 0.8). On the other hand, the dimer spectra in B band region are obtained only with an enhanced interplanar interaction ({alpha} = 1.0-1.2). A broadening of the band in the Q band region of the silicon complex dimer is attributed to an internal rotation of phthalocyanine macrocycles around their C{sub 4} symmetry axis. 44 refs., 7 figs., 3 tabs.

Ishikawa, Naoto; Ohno, Osamu; Kaizu, Youkoh; Kobayashi, Hiroshi [Tokyo Institute of Technology (Japan)

1992-10-29

120

Phthalocyanine-Based Molecularly Imprinted Polymers as Nucleoside Receptors  

PubMed Central

A molecularly imprinted polymer (MIP) for tri-O-acetyladenosine (TOAA), PPM(TOAA), was prepared by the combined use of methacrylic acid (MAA) and Zn(II)tetra(4?-methacryloxyphenoxy) phthalocyanine as functional monomers. This MIP exhibited a higher binding ability for TOAA compared to the MIP prepared using only MAA, PM(TOAA), in batch rebinding tests. Scatchard analysis gave a higher association constant of PPM(TOAA) for TOAA (2.96×104?M?1) than that of PM(TOAA) (1.48×104?M?1). The MIP prepared using only the zinc-phthalocyanine, PP(TOAA), did not show any binding capacity for TOAA. This means that the phthalocyanine in the MIP contributes to higher affinities, although it barely interacts with TOAA. Since selectivity for this kind of MIPs is more important than binding affinity, the binding of TOAA and a structurally related compound, tri-O-acetyluridine (TOAU), on the polymers was investigated. Both PPM(TOAA) and PM(TOAA) exhibited binding affinities for TOAA while they did not show any binding capacity for TOAU.

Longo, Luigia; Vasapollo, Giuseppe

2008-01-01

121

Honeycomb-patterned phthalocyanine films with photo-active antibacterial activities.  

PubMed

We report honeycomb-patterned phthalocyanine (Pc) films fabricated by self-assembly of dodecyloxy-azo-Zinc phthalocyanine (daZnPc) using the breath figure (BF) technique. These ultrathin Pc films exhibit a robust photo-dependent antibacterial effect against Escherichia coli (E. coli). PMID:24098884

Zhou, Xinyu; Chen, Zihui; Wang, Yuzhen; Guo, Yi; Tung, Chen-Ho; Zhang, Fushi; Liu, Xuewu

2013-10-17

122

Langmuir–Blodgett film and carbon paste electrodes based on phthalocyanines as sensing units for taste  

Microsoft Academic Search

In this work, the possibility of using voltammetric electrodes based on phthalocyanine compounds as the sensing units of an electronic tongue has been investigated. Sensors based on monophthalocyanines (including cobalt and copper phthalocyanines) and lanthanide bisphthalocyanines (comprising europium, gadolinium and lutetium bisphthalocyanines and the octa-tertbutyl substituted praseodymium bisphthalocyanine) have been prepared using two different methods: the Langmuir–Blodgett (LB) technique and

A. Arrieta; M. L. Rodriguez-Mendez; J. A. de Saja

2003-01-01

123

Environmentally friendly phthalocyanine catalysts for water decontamination—Non-photocatalytic systems  

Microsoft Academic Search

Macrocyclic porphyrin-like compounds known as phthalocyanines (Pcs) have been shown to produce singlet oxygen species upon illumination with light of an appropriate wavelength. Singlet oxygen is an effective agent for complete oxidation of common water-soluble pollutants including chlorinated phenols. The most active are, in this respect, phthalocyanines bearing Al, Zn and Si central atoms. Although these compounds were proofed to

P. Kluson; M. Drobek; A. Zsigmond; J. Baranyi; P. Bata; S. Zarubova; A. Kalaji

2009-01-01

124

Synergistic effect of ultrasound and phthalocyanines on nucleated erythrocytes in vitro  

Microsoft Academic Search

The synergistic effect of ultrasound (US) and chemicals on cells is known as sonodynamic therapy. In this work, two phthalocyanines (zinc and chloroaluminum) have been tested as potential sonosensitizers for sonodynamic therapy. We studied the effect of US and phthalocyanines on carp erythrocytes, as a nucleated cell model. The level of hemolysis, osmotic fragility, lipid peroxidation and oxidation of hemoglobin

Katarzyna Milowska; Teresa Gabryelak

2005-01-01

125

Enhanced gene delivery using Bubble liposomes and ultrasound for folate-PEG liposomes.  

PubMed

We have previously reported that the transfection efficiency of laminin-derived AG73-peptide labeled polyethyleneglycol-modified liposomes (AG73-PEG liposomes) was enhanced by echo-contrast gas entrapping PEG liposomes (Bubble liposomes, BLs) and ultrasound (US) exposure by improving endosomal escape. However, it has not been well understood whether BLs and US exposure can enhance the transfection efficiency of other carriers except AG73-PEG liposomes. In this study, to evaluate whether BLs and US exposure can be generally applied to gene delivery carriers, we focused on folate as a model ligand and examined whether BLs and US exposure could enhance the transfection efficiency of folate-PEG liposomes. Folate-PEG liposomes could internalize into cells efficiently, whereas they could not deliver genes into cytosol from endosomes sufficiently. BLs and US exposure could enhance the transfection efficiency of folate-PEG liposomes compared with folate-PEG liposomes alone without their direct induction into cells. These results suggested that BLs and US exposure could enhance the transfection efficiency of folate-PEG liposomes in the same manner as AG73-PEG liposomes. Thus, BLs and US exposure may be a promising tool to achieve efficient gene transfection into various gene carriers in general. PMID:22332850

Omata, Daiki; Negishi, Yoichi; Hagiwara, Shoko; Yamamura, Sho; Endo-Takahashi, Yoko; Suzuki, Ryo; Maruyama, Kazuo; Aramaki, Yukihiko

2012-02-15

126

Development of the Liposomes Entrapped Ultrasound Imaging Gas (``Bubble Liposomes'') as Novel Gene Delivery Carriers  

NASA Astrophysics Data System (ADS)

Recently, microbubbles and ultrasound have been investigated with a view to improving the transfection efficiency of nonviral delivery systems for gene by cavitation. However, microbubbles had some problems in terms of stability and targeting ability. To solve these problems, we paid attention to liposomes that had many advantages such as stable and safe in vivo and easy to modify targeting ligand. Previously, we have represented that liposomes are good drug and gene delivery carriers. In addition, we developed that the liposomes (``Bubble liposomes'') were entrapped with perfluoropropane known as ultrasound imaging gas. In this study, we assessed about feasibility of ``Bubble liposomes'' as gene delivery tool utilized cavitation by ultrasound irradiation. ``Bubble liposomes'' could effectively deliver plasmid DNA to cells by combination of ultrasound irradiation without cyototoxicity. This result suggested that ``Bubble liposomes'' might be a new class of tool for gene delivery.

Suzuki, Ryo; Tanaka, Kumiko; Sawamura, Kaori; Takizawa, Tomoko; Utoguchi, Naoki; Negishi, Yoichi; Hagisawa, Kohsuke; Nishioka, Toshihiko; Maruyama, Kazuo

2006-05-01

127

Photochemistry of transition-metal phthalocyanines. Mechanistic aspects of the photochemistry of the acido(phthalocyanine)rhodium(III) complexes investigated by continuous, flash, and laser flash photolysis  

SciTech Connect

Rh(ph)(CH/sub 3/OH)X, X = Cl, Br, or I, has been prepared and characterized. Continuous-wave irradiations of these phthalocyanines in the ultraviolet region of the spectrum, in acetonitrile and acetonitrile-isopropyl alcohol mixtures, result in the redox-induced substitution of the axially coordinated halide ions by the solvent. Even though the overall reaction was photosubstitution, the intermediates observed by conventional and laser flash photolysis were found to be rhodium(II) phthalocyanine and rhodium(III) phthalocyanine ligand radicals. The photoredox processes were attributed to the population of (n..pi..*) ligand-centered excited states that involve the lone electron pair from the bridge nitrogens of the phthalocyanine ligand. 9 figures, 3 tables.

Muralidharan, S.; Ferraudi, G.; Schmatz, K.

1982-08-01

128

The preparation of organic infrared semiconductor phthalocyanine gadolinium (III) and its optical and structural characterizations  

NASA Astrophysics Data System (ADS)

In order to increase the species of organic infrared semiconductor, we synthesized organic infrared semiconductor phthalocyanine gadolinium by using o-phthalodinitrile and GdCl3 as reactants, ammonium molybdate as catalyzer. Under light and dark field modes of microscope, the translucency emerald-like powder of phthalocyanine gadolinium has been observed, the size of the small grain for the sample is around 5?m in diameter, the size of larger grain may reach to several tens of microns. The main vibrational peaks in FT-IR spectrum and Raman spectrum have been assigned. Elementary analysis shows that the experimental data of phthalocyanine gadolinium in the main agree with those of calculated data. The UV-Vis absorption spectrum of the sample indicates the sandwich-like structure of phthalocyanine gadolinium. The organic infrared semiconductor phthalocyanine gadolinium thin film on quartz substrate has been prepared with our synthesized powdered sample by using solution method. The characterizations of XRD and UV-Vis-NIR absorption have been carried out for the phthalocyanine gadolinium thin film on quartz substrate, XRD shows that phthalocyanine gadolinium diffractions occur at 2?=6.851,8.290 and 8.820 degrees, the corresponding plane spacings (d) for the diffraction peaks are 12.8921, 10.6570, and 10.0176Å.The diffraction peaks locate at low diffraction angle, suggesting that the molecular size of the phthalocyanine gadolinium is big that causes the large spacing of crystal planes. The UV-Vis-NIR absorption of phthalocyanine gadolinium thin film on quartz substrate implies that within near infrared band there is a absorption in the 1.3~2.0?m wavelength range peaked at ca. 1.75?m, indicating the important potential application value of phthalocyanine gadolinium in the field of organic infrared optoelectronics.

Tang, Li-Bin; Ji, Rong-Bin; Song, Li-Yuan; Chen, Xue-Mei; Ma, Yu; Wang, Yi-Feng; Qian, Ming; Song, Lei; Su, Hai-Ying; Zhuang, Ji-Sheng; Yang, Rui-Yu

2009-07-01

129

Recent advances with liposomes as pharmaceutical carriers  

Microsoft Academic Search

Liposomes — microscopic phospholipid bubbles with a bilayered membrane structure — have received a lot of attention during the past 30 years as pharmaceutical carriers of great potential. More recently, many new developments have been seen in the area of liposomal drugs — from clinically approved products to new experimental applications, with gene delivery and cancer therapy still being the

Vladimir P. Torchilin

2005-01-01

130

The permeability of liposomes to nonelectrolytes  

Microsoft Academic Search

Summary The effect of temperature on the permeability of nonelectrolytes across liposomal membranes above and below their transition temperature has been studied by using an osmotic method. Below their transition temperature, liposomes are osmotically insensitive structures but, on addition of gramicidin A, the water permeability so increased that the permeability of solutes could be studied. The measured activation energies for

B. Eleazar Cohen

1975-01-01

131

Liposome-Based Flow Injection Immunoassay System,  

National Technical Information Service (NTIS)

A novel flow injection analysis system that contains an immunospecific reactor column and utilizes liposomes for detection is being developed. The fluorophore-loaded liposomes can provide signal enhancement 1,000 - 1,000,000 times per binding event making...

L. Locascio-Brown A. L. Plant R. A. Durst

1988-01-01

132

Liposome retention in size exclusion chromatography  

PubMed Central

Background Size exclusion chromatography is the method of choice for separating free from liposome-encapsulated molecules. However, if the column is not presaturated with lipids this type of chromatography causes a significant loss of lipid material. To date, the mechanism of lipid retention is poorly understood. It has been speculated that lipid binds to the column material or the entire liposome is entrapped inside the void. Results Here we show that intact liposomes and their contents are retained in the exclusion gel. Retention depends on the pore size, the smaller the pores, the higher the retention. Retained liposomes are not tightly fixed to the beads and are slowly released from the gels upon direct or inverted eluent flow, long washing steps or column repacking. Further addition of free liposomes leads to the elution of part of the gel-trapped liposomes, showing that the retention is transitory. Trapping reversibility should be related to a mechanism of partitioning of the liposomes between the stationary phase, water-swelled polymeric gel, and the mobile aqueous phase. Conclusion Retention of liposomes by size exclusion gels is a dynamic and reversible process, which should be accounted for to control lipid loss and sample contamination during chromatography.

Ruysschaert, Tristan; Marque, Audrey; Duteyrat, Jean-Luc; Lesieur, Sylviane; Winterhalter, Mathias; Fournier, Didier

2005-01-01

133

Interactions of liposomes with mammalian cells.  

PubMed

In this review we have attempted to highlight each of the major areas of interest in liposome-cell interactions: the purely physical chemical, the cell biological, and the medical. Liposomes can be generated in a number of ways and are classified as small unilamellar, large unilamellar, and multilamellar vesicles. Although liposomes are easy to prepare, it is important to consider the effects of impurities, and also the possible changes in liposome properties with time (particularly at or below the phase transition temperature). Intelligent application of liposomes to cell biological and clinical problems requires an understanding of their mechanisms of interaction with cells. The mechanisms thus far delineated, largely by studies in vitro, are fusion, endocytosis, lipid transfer, and stable adsorption. In practice, demonstrating the occurrence of a given mechanism in an actual system is difficult because these are not mutually exclusive. Cell type, conditions of incubation, and liposome properties (charge, fluidity, size) are important in determining mechanism and appear to organize the literature effectively. However, this may be an oversimplification resulting from the sketchiness of current information. Liposomes have been used in cell biology to alter the phospholipid and cholesterol composition of cells, to bypass the membrane permeability barrier to normally impermeant solutes, and to promote cell-cell fusion. Perhaps the most fruitful of these applications has been the alteration of cholesterol, which can result in changes in cell permeability and morphology. On the other hand, delivery into cells of liposome-entrapped, water-soluble materials has not yet proved an effective tool in cell biology; delivery, and consequent physiological changes, have been demonstrated, but generally to answer questions about liposome-cell interactions, not to answer questions about the cells. Much of the current interest in liposomes derives from their potential applications in vivo. Liposomes are envisioned as pharmacological capsules for delivery of therapeutic agents in treatment of such conditions as diabetes, enzyme deficiencies, heavy metal poisoning, and neoplasms. Although much of the literature to date has been concerned with the end applications, it seems clear that a more systematic approach to the pharmacokinetics of liposomes will be necessary. In particular, such aspects as their leakage rates and their ability to cross cell and anatomical barriers require further study. Targeting of liposomes to particular cells or tissues will be essential for many applications. Finally, it must be remembered that all of these in vivo applications of liposomes are future tense; as with other technologies, passage from demonstration of the phenomenon to practical application is likely to be arduous. PMID:352245

Pagano, R E; Weinstein, J N

1978-01-01

134

Neuronal chemotaxis by optically manipulated liposomes  

NASA Astrophysics Data System (ADS)

We probe chemotaxis of single neurons, induced by signalling molecules which were optically delivered from liposomes in the neighbourhood of the cells. We implemented an optical tweezers setup combined with a micro-dissection system on an inverted microscope platform. Molecules of Netrin-1 protein were encapsulated into micron-sized liposomes and manipulated to micrometric distances from a specific growth cone of a hippocampal neuron by the IR optical tweezers. The molecules were then released by breaking the liposomes with UV laser pulses. Chemotaxis induced by the delivered molecules was confirmed by the migration of the growth cone toward the liposome position. Since the delivery can be manipulated with high temporal and spatial resolution and the number of molecules released can be controlled quite precisely by tuning the liposome size and the solution concentration, this technique opens new opportunities to investigate the effect of physiological active compounds as Netrin-1 to neuronal signalling and guidance, which represents an important issue in neurobiology.

Pinato, G.; Lien, L. T.; D'Este, E.; Torre, V.; Cojoc, D.

2011-08-01

135

Liposome delivery of aminoglycosides in burn wounds.  

PubMed

The current study evaluated the pharmacodynamics of topically applied antimicrobials incorporated into radiolabeled liposomes. Radiolabeled 125I-phenyldecanoic acid was used in the formulation of small unilamellar liposomes. Sephadex (cross-linked dextran beads) G-50 columns were run to determine the per cent of radioactivity incorporated into liposomes and persistence of radioactive tag on the liposome after two weeks (greater than 95 per cent) remained incorporated. On the day of the experiment, 31 adult Sprague Dawley rats were subjected to a 10 per cent total body surface area full thickness burn (Walker burn model). All rats were treated with topical application of 0.3 milliliters of tobramycin entrapped in 125I-liposomes, and burn wounds were covered with Opsite (Winfield Laboratories). This formulation resulted in each rat receiving 14 milligrams per kilogram of tobramycin with a specific activity of 10.41 microcuries. Rats were sacrificed at several time periods after burn injury (nine after 24 hours, 12 after 48 hours, 11 after 72 hours). At these time intervals, serum and tissue tobramycin levels were measured, burn dressing, burn tissue and splanchnic organs were harvested and radioactivity was assessed with a gamma scintillation counter to determine tissue concentration of 125I-liposome tobramycin. Concentration of tobramycin in the serum was negligible at 24, 48 and 72 hours postburn, but was significant in the burn tissues at these times. The radioactive recovery data demonstrated that the majority (greater than 90 per cent) of the recovered liposomes remained at the site of application (the burn wound). No splanchnic organs had greater than 2 per cent of the recovered 125I-liposomes at any time period. These data suggest that, in burn wounds, tobramycin incorporated into liposomes remain at the site of initial application, resulting in high local concentrations with little systemic absorption and confirm that liposomes provide an effective vehicle for delivery of antimicrobials at the site of the burn injury. PMID:1570621

Price, C I; Horton, J W; Baxter, C R

1992-05-01

136

Paramagnetic liposomes as MRI contrast agents: influence of liposomal physicochemical properties on the in vitro relaxivity.  

PubMed

The in vitro contrast efficacy of liposome encapsulated gadolinium-[10-(2-hydroxypropyl)-1,4,7,10-tetraazacyclododecane-1, 4,7-triacetic acid] (GdHPDO3A) has been assessed by relaxometry. The internal concentrations were 150 and 250 mM Gd. Two types of liposome compositions were investigated: a phospholipid blend consisting of both hydrogenated phosphatidylcholine (HPC) and phosphatidylserine (HPS) with a gel-to-liquid crystalline phase transition temperature (Tm) of 50 degrees C, and a mixture of dipalmitoylphosphatidylcholine (DPPC) and dipalmitoylphosphatidylglycerol (DPPG) with a Tm of 41 degrees C. The investigated liposome size range was 70-400 nm. The T1 and T2 relaxivities (r1 and r2) of liposome encapsulated GdHPDO3A were significantly reduced at 37 degrees C and 0.47 T, compared to those of non-liposomal metal chelate, due to an exchange limitation of the dipolar relaxation process. The highest relaxivity values were obtained for the DPPC/DPPG liposomes, and were attributed to a higher liposome water permeability and to a more efficient water exchange across the membrane. A reduction in liposome size increased the r1, confirming the exchange limited dipolar relaxation. The increased r1 with increasing temperature demonstrated the prerequisite of rapid water exchange between the interior and exterior of the liposome for efficient dipolar relaxation enhancement. Susceptibility effects were present in the liposome systems as the r2/r1 ratio increased with increasing liposome size and internal Gd concentration. In summary, the current work has shown the influence of key physicochemical properties, such as liposome size, membrane composition and permeability, on the in vitro relaxivity of liposome encapsulated GdHPDO3A. PMID:9888401

Fossheim, S L; Fahlvik, A K; Klaveness, J; Muller, R N

1999-01-01

137

UV visible spectral study on the stability of lead phthalocyanine complexes  

NASA Astrophysics Data System (ADS)

UV visible electronic spectral study has been done on lead phthalocyanine (PbPc), lead tetranitro phthalocyanine (PbTNP) and lead tetraamino phthalocyanine (PbTAP) in dimethyl sulphoxide (DMSO) and H2SO4 media. Metal free phthalocyanine (H2Pc) is insoluble in DMSO and soluble in conc. H2SO4. The study has been extended to H2Pc to compare the stability of phthalocyanine structure with the PbPc complexes in H2SO4 medium. PbPc complexes are stable in DMSO, and all the complexes are more stable in 36 N H2SO4 than in 30 N and 28 N H2SO4 media. Further, complete demetallation and degradation of the phthalocyanine structure have been observed for all the PbPc complexes in 36 N H2SO4 medium within a week's time. The stability of these complexes is compared with H2Pc in H2SO4 medium. The decomposition reactions in H2SO4 media for H2Pc, PbPc, PbTNP and PbTAP are followed spectrophotometrically and rate constants were calculated. The decomposition reactions were found to follow the first-order kinetics with respect to the concentration of their respective phthalocyanine derivatives.

Mohan Kumar, T. M.; Achar, B. N.

2006-11-01

138

Magnetism and multiplets in metal-phthalocyanine molecules  

NASA Astrophysics Data System (ADS)

Magnetism and multiplets for metal-phthalocyanine (MPc) molecules with transition-metals (M) of Mn and Co were investigated based on the constraint density functional theory calculations by imposing density matrix constraint on the d-orbital occupation numbers. For the MnPc, the ground state is found to be the 4Eg state with the perpendicular magnetic anisotropy with respect to the molecular plane, while for the CoPc, the ground state is the 2A1g state with a planar magnetic anisotropy.

Kitaoka, Y.; Sakai, T.; Nakamura, K.; Akiyama, T.; Ito, T.

2013-05-01

139

Photoluminescence of nitro-substituted europium (III) phthalocyanines  

SciTech Connect

Europium monophthalocyanine Eu(acac)Pc, europium monotetranitrophthalocyanine Eu(acac)Pc(NO{sub 2}){sub 4}, and heteroleptic europium tetranitrobisphthalocyanine Eu(Pc)(Pc(NO{sub 2}){sub 4}) are synthesized. The spectral characteristics of the phthalocyanine complexes in the visible and near-infrared regions are studied. The photoluminescence spectra are recorded. The luminescence bands are detected in the regions 450-500 nm (S{sub 2} {yields} S{sub 0}) and 670-730 nm (S{sub 1} {yields} S{sub 0}). The peaks are attributed to electronic transitions in the organic ligands.

Ziminov, A. V., E-mail: ziminov@inbox.ru; Polevaya, Yu. A.; Jourre, T. A.; Ramsh, S. M. [St. Petersburg State Institute of Technology (Technical University) (Russian Federation); Mezdrogina, M. M. [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation); Poletaev, N. K. [St. Petersburg State Institute of Technology (Technical University) (Russian Federation)

2010-08-15

140

Porphyrins XV. Vapor absorption spectra and stability: Phthalocyanines  

Microsoft Academic Search

Vapor absorption spectra in the range 800-200 mmu are given for free base phthalocyanine (H2Pc), MgPc, TiOPc, VOPc, CrPc, FePc, CoPc, NiPc, CuPc, ZuPc, SnCl2Pc, and PbPc. Electronic bands Q, B, N, L, C characteristic of the ring are found in the regions 660 mmu (15 200 cm-1), 320 mmu (31 300 cm-1), 275 mmu (36 400 cm-1), 245 mmu

Lawrence Edwards; Martin Gouterman

1970-01-01

141

Conduction processes in tin- and silicon-phthalocyanine thin films  

SciTech Connect

Electronic conduction studies have been carried out on evaporated tin- and silicon-phthalocyanine thin films. The samples showed carrier excitation via a field-lowering mechanism with a logJ{alpha}V {sup 1/2} plot and the current density-voltage (J-V) characteristics were studied. Both polarities showed two characteristic regions in the J-V plots at low and high voltages respectively leading to the conclusion that electrical conduction proceeds via Schottky and Poole-Frenkel emission.

Flores Gracia, F. [Centro de Investigaciones en Dispositivos Semiconductores, Instituto de Ciencias, Benemerita Universidad Autonoma de Puebla, A. P. 1651, Puebla, Pue. 72000 Mexico (Mexico)]. E-mail: fjflor@siu.buap.mx; Sosa Sanchez, A. [Centro de Investigaciones en Dispositivos Semiconductores, Instituto de Ciencias, Benemerita Universidad Autonoma de Puebla, A. P. 1651, Puebla, Pue. 72000 (Mexico); Sosa Sanchez, J. Luis [Centro de Investigaciones en Dispositivos Semiconductores, Instituto de Ciencias, Benemerita Universidad Autonoma de Puebla, A. P. 1651, Puebla, Pue. 72000 (Mexico)

2007-08-15

142

A series of asymmetrical phthalocyanines: synthesis and near infrared properties.  

PubMed

We report here the preparation of asymmetrical phthalocyanine dimers 1a-3a, which are endowed with novel charge transfer bands at 1,151-1,154 nm and strong NIR luminescences at 840-860 nm and 1,600-1,650 nm. Through H-bonding interaction, 1a-3a are inclined to self-assemble into hexrod nanotubes at the interface of CHCl? and CH?H. Our results provide further insights into the interaction in molecular dimers, and suggest that 1a-3a have potential application in magnets and supramolecular architectures. PMID:23603946

Huang, Guoqing; Li, Jianxi; Cong, Fangdi; Li, Chao; Chu, Xixi; Meng, Yanyan; Du, Guotong; Du, Xiguang

2013-04-19

143

Spectroscopic and microscopic investigations of phthalocyanine aggregates on Gold(111)  

NASA Astrophysics Data System (ADS)

Self-assembled organic pi systems are of interest because of their potential applications in light harvesting and electron transfer. Phthalocyanines (Pc) demonstrate desirable photonic and electronic properties, thus making them excellent candidates for functional nanostructures. The specific focus of this research has been the nanoscale aggregation of a metal-free organic dye, tetrasulfonic acid phthalocyanine (TSPc) and includes the use of UV-visible Spectroscopy, Resonance Light Scattering Spectroscopy (RLS), X-ray Photoelectron Spectroscopy (XPS), Atomic Force Microscopy (AFM) and ambient and ultra-high-vacuum Scanning Tunneling Microscopy (STM) and Scanning Tunneling Spectroscopy (STS). The UV-visible absorption studies show that TSPc aggregates upon dissolution in water and obeys Beer's Law within the concentration range of 10 -7M to 10-4M, indicating that TSPc concentration has no further effect on aggregation in aqueous solution. In addition, both ionic strength in NaCl and pH changes in the presence of NaOH, HCl or acetic acid (HAc) do affect aggregation. The RSL studies confirm these effects of pH only in the presence of HAc. The XPS studies show that the ratio of non-protonated to protonated nitrogens does not change with decreasing solution pH. STM images of TSPc deposited from pH<1 solutions reveal ordered branched web-like assemblies hundreds of nanometers in length, generally 2 nm tall and having variable widths. STM imaging shows TSPc aggregates decrease in order as pH increases. STM images of TSPc deposited from solutions with pH>10 show monolayer coverage of TSPc in salt form. High-resolution UHV-STM images of TSPc aggregates deposited from pH 0 solution on Au(111) reveal detailed coherent columnar architecture with the phthalocyanine macrocycles orientated parallel to the substrate surface. OMTS was used to identify the HOMO and LUMO of the TSPc aggregates and the results are contrasted with the same molecular states in unsubstituted metallated phthalocyanines (MPc). The positions of the filled and the empty states of the TSPc are comparable to those of other unsubstituted MPc's indicating that the electronegative sulfonate substituents have minimal effect on the electronic properties of the macrocycle. The HOMO-LUMO separation of TSPc is slightly above 2 eV, a value consistent with the literature assignments for the Pc ring band gap.

Nishida, Krista Rachel Akiko

144

The complex nature of phthalocyanine/gold interfaces  

NASA Astrophysics Data System (ADS)

We compare the electronic properties of the interface between Au(1 0 0) and cobalt phthalocyanine (CoPc), fluorinated F16CoPc as well as CuPc using X-ray photoemission spectroscopy and valence band ultra-violet photoemission spectroscopy. Our results show that in addition to the formation of an interface dipole at the interfaces of CoPc and F16CoPc to gold, there is a local charge transfer to the central Co ion, which as a result is reduced to Co(I).

Lindner, Susi; Treske, Uwe; Knupfer, Martin

2013-02-01

145

Quantifying the effects of melittin on liposomes.  

PubMed

Melittin, the soluble peptide of bee venom, has been demonstrated to induce lysis of phospholipid liposomes. We have investigated the dependence of the lytic activity of melittin on lipid composition. The lysis of liposomes, measured by following their mass and dimensions when immobilised on a solid substrate, was close to zero when the negatively charged lipids phosphatidyl glycerol or phosphatidyl serine were used as the phospholipid component of the liposome. Whilst there was significant binding of melittin to the liposomes, there was little net change in their diameter with melittin binding reversed upon salt injection. For the zwitterionic phosphatidyl choline the lytic ability of melittin is dependent on the degree of acyl chain unsaturation, with melittin able to induce lysis of liposomes in the liquid crystalline state, whilst those in the gel state showed strong resistance to lysis. By directly measuring the dimensions and mass changes of liposomes on exposure to melittin using Dual Polarisation Interferometry, rather than following the florescence of entrapped dyes we attained further information about the initial stages of melittin binding to liposomes. PMID:17092481

Popplewell, J F; Swann, M J; Freeman, N J; McDonnell, C; Ford, R C

2006-05-23

146

Preparation and ocular pharmacokinetics of ganciclovir liposomes.  

PubMed

Ophthalmic liposomes of ganciclovir (GCV) were prepared by the reverse phase evaporation method, and their ocular pharmacokinetics in albino rabbits were compared with those obtained after dosing with GCV solution. The in vitro transcorneal permeability of GCV liposomes was found to be 3.9-fold higher than that of the solution. After in vivo instillation in albino rabbits, no difference was found in the precorneal elimination rate of GCV from liposome vs solution dosing. The aqueous humor concentration-time profiles of both liposomes and solution were well described by 2-compartmental pharmacokinetics with first-order absorption. The area under the curve of the aqueous humor concentration-time profiles of GCV liposomes was found to be 1.7-fold higher than that of GCV solution. Ocular tissue distribution of GCV from liposomes was 2 to 10 times higher in the sclera, cornea, iris, lens, and vitreous humor when compared with those observed after solution dosing. These results suggested that liposomes may hold some promise in ocular GCV delivery. PMID:18170984

Shen, Yan; Tu, Jiasheng

2007-12-07

147

Delivery of Plasmid DNA into Mammalian Cell Lines Using pH-Sensitive Liposomes: Comparison with Cationic Liposomes  

Microsoft Academic Search

We compare the transfection efficiency of plasmid DNA encoding either luciferase or (ß-galactosidase encapsulated in pH-sensitive liposomes or non-pH-sensitive liposomes or DNA complexed with cationic liposomes composed of dioleoyloxypropyl-trimethylammonium:dioleoylphosphatidyl-ethanolamine (1:1, w\\/w) (Lipofectin) and delivered into various mammalian cell lines. Cationic liposomes mediate the highest transient transfection level in all cell-lines examined. pH-sensitive liposomes, composed of cholestryl hemisuccinate and dioleoylphosphatidylethanolamine at

Jean-Yves Legendre; Francis C. Szoka Jr

1992-01-01

148

Preparation of passive bilayer liposomes.  

PubMed

In studies of in-membrane molecular interactions, need may arise for a matrix that cannot itself interact, except hydrophobically, with the reactants. Such a bilayer matrix should, ideally, consist of only a hydrophobic zone without ionic outer layers and without hydrogen belts (the membrane strata containing CO and OH groups). However, because of the necessity of anchoring the bilayer to its aqueous surroundings, there must be polar substituents. Hydrophilic ether groups in the form of polyoxyethylenes can provide nearly sufficient anchoring and yet not confer unwanted reactivity to the membrane since they are only very weak H-bond acceptors. The stability of the bilayer is ensured by the presence of a few percent of an amphiphile (which may be the substrate to be studied, e.g. a phospholipid) or by a free polyethylene hydroxy group far remote from the original hydrogen belt region. Our most impermeable liposomes consisted of O-methylcholesterol/O-methoxyethoxyethoxyethylcholesterol; the most readily prepared liposomes were made from O-methylcholesterol and hydroxy(ethoxy)4dodecane (Brij 30) or Triton. PMID:3338101

Zingoni, J; Chauhan, A; Chauhan, V P; Brockerhoff, H

1988-01-01

149

The role of cavitation in liposome formation.  

PubMed

Liposome size is a vital parameter of many quantitative biophysical studies. Sonication, or exposure to ultrasound, is used widely to manufacture artificial liposomes, yet little is known about the mechanism by which liposomes are affected by ultrasound. Cavitation, or the oscillation of small gas bubbles in a pressure-varying field, has been shown to be responsible for many biophysical effects of ultrasound on cells. In this study, we correlate the presence and type of cavitation with a decrease in liposome size. Aqueous lipid suspensions surrounding a hydrophone were exposed to various intensities of ultrasound and hydrostatic pressures before measuring their size distribution with dynamic light scattering. As expected, increasing ultrasound intensity at atmospheric pressure decreased the average liposome diameter. The presence of collapse cavitation was manifested in the acoustic spectrum at high ultrasonic intensities. Increasing hydrostatic pressure was shown to inhibit the presence of collapse cavitation. Collapse cavitation, however, did not correlate with decreases in liposome size, as changes in size still occurred when collapse cavitation was inhibited either by lowering ultrasound intensity or by increasing static pressure. We propose a mechanism whereby stable cavitation, another type of cavitation present in sound fields, causes fluid shearing of liposomes and reduction of liposome size. A mathematical model was developed based on the Rayleigh-Plesset equation of bubble dynamics and principles of acoustic microstreaming to estimate the shear field magnitude around an oscillating bubble. This model predicts the ultrasound intensities and pressures needed to create shear fields sufficient to cause liposome size change, and correlates well with our experimental data. PMID:17766335

Richardson, Eric S; Pitt, William G; Woodbury, Dixon J

2007-08-31

150

The Role of Cavitation in Liposome Formation  

PubMed Central

Liposome size is a vital parameter of many quantitative biophysical studies. Sonication, or exposure to ultrasound, is used widely to manufacture artificial liposomes, yet little is known about the mechanism by which liposomes are affected by ultrasound. Cavitation, or the oscillation of small gas bubbles in a pressure-varying field, has been shown to be responsible for many biophysical effects of ultrasound on cells. In this study, we correlate the presence and type of cavitation with a decrease in liposome size. Aqueous lipid suspensions surrounding a hydrophone were exposed to various intensities of ultrasound and hydrostatic pressures before measuring their size distribution with dynamic light scattering. As expected, increasing ultrasound intensity at atmospheric pressure decreased the average liposome diameter. The presence of collapse cavitation was manifested in the acoustic spectrum at high ultrasonic intensities. Increasing hydrostatic pressure was shown to inhibit the presence of collapse cavitation. Collapse cavitation, however, did not correlate with decreases in liposome size, as changes in size still occurred when collapse cavitation was inhibited either by lowering ultrasound intensity or by increasing static pressure. We propose a mechanism whereby stable cavitation, another type of cavitation present in sound fields, causes fluid shearing of liposomes and reduction of liposome size. A mathematical model was developed based on the Rayleigh-Plesset equation of bubble dynamics and principles of acoustic microstreaming to estimate the shear field magnitude around an oscillating bubble. This model predicts the ultrasound intensities and pressures needed to create shear fields sufficient to cause liposome size change, and correlates well with our experimental data.

Richardson, Eric S.; Pitt, William G.; Woodbury, Dixon J.

2007-01-01

151

The adjuvant mechanism of cationic dimethyldioctadecylammonium liposomes  

PubMed Central

Cationic liposomes are being used increasingly as efficient adjuvants for subunit vaccines but their precise mechanism of action is still unknown. Here, we investigated the adjuvant mechanism of cationic liposomes based on the synthetic amphiphile dimethyldioctadecylammonium (DDA). The liposomes did not have an effect on the maturation of murine bone-marrow-derived dendritic cells (BM-DCs) related to the surface expression of major histocompatibility complex (MHC) class II, CD40, CD80 and CD86. We found that ovalbumin (OVA) readily associated with the liposomes (> 90%) when mixed in equal concentrations. This efficient adsorption onto the liposomes led to an enhanced uptake of OVA by BM-DCs as assessed by flow cytometry and confocal fluorescence laser-scanning microscopy. This was an active process, which was arrested at 4° and by an inhibitor of actin-dependent endocytosis, cytochalasin D. In vivo studies confirmed the observed effect because adsorption of OVA onto DDA liposomes enhanced the uptake of the antigen by peritoneal exudate cells after intraperitoneal injection. The liposomes targeted antigen preferentially to antigen-presenting cells because we only observed a minimal uptake by T cells in mixed splenocyte cultures. The adsorption of antigen onto the liposomes increased the efficiency of antigen presentation more than 100 times in a responder assay with MHC class II-restricted OVA-specific T-cell receptor transgenic DO11.10 T cells. Our data therefore suggest that the primary adjuvant mechanism of cationic DDA liposomes is to target the cell membrane of antigen-presenting cells, which subsequently leads to enhanced uptake and presentation of antigen.

Smith Korsholm, Karen; Agger, Else Marie; Foged, Camilla; Christensen, Dennis; Dietrich, Jes; Andersen, Claire Swetman; Geisler, Carsten; Andersen, Peter

2007-01-01

152

Drug Transport to Brain with Targeted Liposomes  

PubMed Central

Summary: Antibody-conjugated liposomes or immunoliposomes are particulate drug carriers that can be used to direct encapsulated drug molecules to diseased tissues or organs. The present review discusses examples of successful applications of this technology to achieve drug transport across the blood-brain barrier. In addition, information will be provided on practical aspects such as phospholipid compositions of liposomes, antibody coupling technologies, large-scale production of liposomes, and obstacles related to drug loading of the carrier. Prospects of future uses of immunoliposome-based drug delivery systems such as gene therapy of the brain and clinical trials are discussed.

Schnyder, Anita; Huwyler, Jorg

2005-01-01

153

Bubble liposomes and ultrasound promoted endosomal escape of TAT-PEG liposomes as gene delivery carriers.  

PubMed

We have previously developed laminin-derived AG73 peptide-labeled poly(ethylene glycol)-modified liposomes (AG73-PEG liposomes) for selective cancer gene therapy and reported that Bubble liposomes (BLs) and ultrasound (US) exposure could accelerate the endosomal escape of AG73-PEG liposomes, leading to the enhancement of transfection efficiency; however, it is still unclear whether BLs and US exposure can also enhance the transfection efficiency of other vectors. We therefore assessed the effect of BLs and US exposure on the gene transfection efficiency of trans-activating transcriptor (TAT) peptide modified PEG liposomes. Although TAT-PEG liposomes were efficiently internalized into cells, the efficacy of endosomal escape was insufficient. The transfection efficiencies of TAT-PEG liposomes were enhanced by about 30-fold when BLs and US exposure were used. We also confirmed that BLs and US exposure could not enhance the direct transportation of TAT-PEG liposomes into cells. Confocal microscopy showed that BLs and US exposure promoted endosomal escape of TAT-PEG liposomes. Our results suggested that BLs and US exposure could enhance transfection efficiency by promoting endosomal escape, which was independent of modified molecules of carriers. Thus, BLs and US exposure can be a useful tool to achieve efficient gene transfection by improving endosomal escape of various carriers. PMID:22023188

Omata, Daiki; Negishi, Yoichi; Hagiwara, Shoko; Yamamura, Sho; Endo-Takahashi, Yoko; Suzuki, Ryo; Maruyama, Kazuo; Nomizu, Motoyoshi; Aramaki, Yukihiko

2011-11-04

154

Electrophoretic deposition of phthalocyanine in organic solutions containing trifluoroacetic acid.  

PubMed

The absorption spectra of copper phthalocyanine (CuPc) 1,2-dichloroethane (DCE) solutions containing trifluoroacetic acid (TFAA) shows that the number of protons coordinating to the CuPc molecule was 1 and 2 for the first and second proton adducts, respectively, which indicates the formations of CuPcH(+) and CuPcH(2)(2+). This CuPc molecule may act as a catalyst to dissociate TFAA into trifluoroacetate anion (A(-)) and H(+) and form the proton adducts. The electrical conductivity dependence of the solution on CuPc concentration also supports this mechanism. A dense film of CuPc was deposited on an indium tin oxide cathode plate by electrophoresis of the solution. Similar dense films of a wide variety of phthalocyanines (MPc; M = Cu, H(2), Fe, Ni, Zn, Pb, VO) were also deposited using this method. Similar films of CuPc were also formed using dichloromethane (DCM) and 1,1,1-trichloroethane (TCE) in place of DCE. Depositions are ascribed to the migration of positively charged monomers (i.e., protonated MPc). Scanning electron microscopy revealed that these films are composed of fibrous crystallites, size of which was found to increase with the electrophoresis time, the strength of the applied electrical field and the concentration of CuPc in the bath. The influence of the dielectric constant of the organic solvent on the film growth is discussed. PMID:20886893

Shrestha, Nabeen K; Kohn, Hideki; Imamura, Mitsuharu; Irie, Kazunobu; Ogihara, Hitoshi; Saji, Tetsuo

2010-10-01

155

Photocatalytic degradation of atrazine by porphyrin and phthalocyanine complexes.  

PubMed

This study principally focused on a new kind of photochemical reaction catalyst: porphyrin and phthalocyanine complexes. In a first step, the preparation of the catalysts was optimized. A resin has been chosen to be the support of the complexes. Efficiency of catalytic activity is performed on the degradation of a pesticide: atrazine. The best atrazine degradation occurs with 4.6% of complexes versus substrate. The role of the surface has also been shown to be important. Then, their performances were demonstrated in terms of kinetics and degradation routes, compared to a classical catalyst: titanium dioxide. This study seeks to assess the efficiency of these systems both in a mercury lamp reactor and under solar irradiation which reduces energy costs. The best atrazine degradation half-life found for the complexes is about 200 min with the iron phthalocyanine. These catalysts exhibit particular oxidation activities. Indeed, the degradation routes have been found different between the semi-conductor and the metallic complexes. These complexes are able to cleave the triazinic ring more efficiently than the titanium dioxide. PMID:11057600

Héquet, V; Le Cloirec, P; Gonzalez, C; Meunier, B

2000-08-01

156

Effect of antiooxidants on phthalocyanine photosensitization of human erythrocytes  

NASA Astrophysics Data System (ADS)

Photohemolysis of human erythrocytes sensitized by sulfonated aluminum phthalocyanine was used as an endpoint to study possible chemical modifications of photodynamic therapy. Ascorbate, in concentrations up to 0.1 mM, had a small protective effect. In larger amounts it stimulated the rate of photohemolysis in a concentration dependent manner up to 1 mM, by a factor of 2. Azide and D2O tests indicated some participation of singlet oxygen, although to a lesser extent than in the absence of ascorbate. Kinetic considerations augur for reaction path initiated by an interaction of excited sensitizer-ascorbate, parallel to the singlet oxygen- mediated process. Because of the ubiquitous presence of ascorbate in human tissues in concentrations comparable to those of dissolved oxygen, it is a reasonable estimation that in photodynamic therapy, a fraction of the photodynamic damage proceeds via a Type I, ascorbate-assisted mechanism. Tocopherol had an effect opposite to that of ascorbate, namely it inhibited the photohemolysis. Likewise, quercetin, a plant flavonoid, was protective against phthalocyanine-induced photohemolysis.

Ben-Hur, Ehud; Rosenthal, Ionel

1993-06-01

157

Liposome Drug Products Chemistry, Manufacturing, and ...  

Center for Drug Evaluation (CDER)

Text VersionGuidance for Industry Liposome Drug Products Chemistry, Manufacturing, and Controls; Human ... Chemistry, Manufacturing, and Controls; Human ... More results from www.fda.gov/downloads/drugs/guidancecomplianceregulatoryinformation

158

Pegylated liposomal doxorubicin in ovarian cancer  

PubMed Central

The encapsulation of doxorubicin in a pegylated liposomal matrix led to a reformulated agent with a different toxicity profile and improved clinical utility. Liposomal doxorubicin is devoid of the cardiac toxicity associated with doxorubicin, but is associated with predictable muco-cutaneous toxicity. The liposomal formulation leads to improved delivery to the target tumor tissue, allowing enhanced uptake by cancer cells. These properties translate into clinical utility in recurrent ovarian cancer as demonstrated by phase II and III trials, this proven clinical efficacy leading to FDA approval in second-line therapy for ovarian cancer. New combinations with cytotoxics, in particular with carboplatin, have demonstrated an acceptable toxicity profile and clinical utility in platinum-sensitive ovarian cancer. A favorable toxicity profile renders liposomal doxorubicin an ideal partner for combination regimens with other cytotoxics, and more recently with biological agents. Such combinations are the subject of ongoing clinical trials.

Strother, Robert; Matei, Daniela

2009-01-01

159

Structure-function relationships in unsymmetrical zinc phthalocyanines for dye-sensitized solar cells.  

PubMed

A series of unsymmetrical zinc phthalocyanines bearing an anchoring carboxylic function linked to the phthalocyanine ring through different spacers were designed for dye-sensitised solar cells (DSSC). The modification of the spacer group allows not only a variable distance between the dye and the nanocrystalline TiO(2), but also a distinct orientation of the phthalocyanine on the semiconductor surface. The photovoltaic data show that the nature of the spacer group plays a significant role in the electron injection from the photo-excited dye into the nanocrystalline TiO(2) semiconductor, the recombination rates and the efficiency of the cells. The incident monochromatic photon-to-current conversion efficiency (IPCE) for phthalocyanines bearing an insulating spacer is as low as 9%, whereas for those with a conducting spacer an outstanding IPCE 80% was obtained. PMID:19338034

Cid, Juan-José; García-Iglesias, Miguel; Yum, Jun-Ho; Forneli, Amparo; Albero, Josep; Martínez-Ferrero, Eugenia; Vázquez, Purificación; Grätzel, Michael; Nazeeruddin, Mohammad K; Palomares, Emilio; Torres, Tomás

2009-01-01

160

Effect of Substituents on UV-Vis Spectra and RSA Properties of Phthalocyanine Compounds.  

National Technical Information Service (NTIS)

The use of optically transparent materials to modulate or impede laser light in a real-time setting is significant. This goal stimulates an interest in metalloporphyrins, phthalocyanines (PCs), naphthalocyanins, and their derivatives. The most desired der...

A. Rawlett J. Andzelm J. Orlicki J. Snyder K. Baldridge

2007-01-01

161

Electronic Structure of Iron Phthalocyanine and Its Analogs: A Theoretical Study.  

National Technical Information Service (NTIS)

Molecular electronic structures of the dianions and iron complexes of phthalocyanine and other macrocyclic compounds (i.e., tetrabenzoporphyrin, tetrazaporphyrin and porphyrin) which are of interest in oxygen electrocatalysis have been calculated using CN...

N. H. Sabelli L. K. Lee C. A. Melendres

1981-01-01

162

Influence of different peripheral substituents on the nonlinear optical properties of cobalt phthalocyanine core  

SciTech Connect

In this article, we show how the substituting different peripheral substituents around the cobalt phthalocyanine core correlate with nonlinear optical properties. We present the results on nonlinear optical properties of solution of cobalt phthalocyanine (CoPc), cobalt phthalocyanine with DNA-CTMA surfactant complex (CoPc-DNA-CTMA), and cobalt phthalocyanine with liquid crystal (CoPc-LC) measured by degenerate four-wave mixing (DFWM) method at the 532 nm wavelength region. We found that the values of third-order nonlinear optical susceptibility ({chi}{sup <3>}) of CoPc-LC and CoPc-DNA-CTMA increase in comparison with the value of the third-order nonlinear optical susceptibilities of CoPc. We supposed that this is caused by increase of the charge-transfer effects and of the dipole moments of the molecule with the increase of the chain length.

Derkowska, B.; Wojdyla, M.; Bala, W.; Jaworowicz, K.; Karpierz, M.; Grote, James G.; Krupka, O.; Kajzar, F.; Sahraoui, B. [Institute of Physics, N. Copernicus University, GrudziaPdzka 5/7, 87-100 Torun (Poland); Optics Division, Faculty of Physics, Warsaw University of Technology, Koszykowa 75, 00-681 Warsaw (Poland); Air Force Research Laboratory Materials and Manufacturing Directorate, Wright-Patterson Air Force Base, 3005 Hobson Way, Dayton, Ohio 45433-7707 (United States); Laboratory POMA, UMR CNRS 6136, University of Angers, 2 Boulevard Lavoisier, 49045 Angers (France)

2007-04-15

163

Comparative semiempirical study of oxygen binding to model iron complexes of phthalocyanine and porphyrin  

SciTech Connect

Molecular electronic structures of the danions and iron complexes of phthalocyanine and related macrocyclic compounds (i.e., tetrabenzoporphyrin, tetraazaporphyrin, and porphyrin) which are of interest in electrocatalysis have been calculated with semiempirical all-valence electron methods. Significant differences are found between the electron distributions in phthalocyanine and porphyrin dianions due mainly to the nature of the atom bridging the indole or pyrrole ligands. Iron complexes of both macrocyclics also show significant electronic differences, with the iron atom in an intermediate spin state in phthalocyanine and a high spin state in porphyrin. Oxygen binding to the iron center in model compounds of both complexes was also studied. The side-on configuration appears to be preferred in the oxygen-phthalocyanine system and end-on bonding in the oxygen-porphyrin complex.

Sabelli, N.H. (Univ. of Illinois, Chicago); Melendres, C.A.

1982-10-28

164

A squaraine-phthalocyanine ensemble: towards molecular panchromatic sensitizers in solar cells.  

PubMed

A supramolecular phthalocyanine-squaraine ensemble which exhibits a large coverage of the solar spectrum from 850 to 250 nm has been prepared and characterized both photophysically and in bulk heterojunction solar cells. PMID:19617963

Silvestri, Fabio; López-Duarte, Ismael; Seitz, Wolfgang; Beverina, Luca; Martínez-Díaz, M Victoria; Marks, Tobin J; Guldi, Dirk M; Pagani, Giorgio A; Torres, Tomás

2009-04-20

165

Interaction of copper nanoparticles with liposomes  

Microsoft Academic Search

The reduction of copper(II) ions in an aqueous dispersion of positively charged liposomes results in the formation of stable\\u000a sols of a complex of copper nanoparticles with the surface of liposomes. The mean size (7 nm) and the narrow size distribution\\u000a of metal nanoparticles are similar to those observed in the case of metal sol formation in polymer solutions. The

G. Yu. Ostaeva; A. A. Yaroslavov; E. D. Selishcheva; D. A. Davydov; I. M. Papisov

2008-01-01

166

Molecular Interactions Between Alcohols and Metal Phthalocyanine Thin Films for Optical Gas Sensor Applications  

Microsoft Academic Search

Optically active organic gas sensors represent a promising molecular sensing device with low power consumption. We report\\u000a experimental and computational investigations into the molecular interactions of metal phthalocyanine thin films with alcohol\\u000a vapor. In the gas-sensing regime, the interactions of zinc phthalocyanine and alcohol molecules were studied by the Density\\u000a Functional Theory (DFT) calculations, in comparison to the x-ray absorption

Sureeporn Uttiya; Sumana Kladsomboon; Onanong Chamlek; Wiriya Suwannet; Tanakorn Osotchan; Teerakiat Kerdcharoen; Martin Brinkmann; Sirapat Pratontep

2009-01-01

167

In vitro cytotoxicity assessment of phthalocyanines on virus-transformed animal cells  

Microsoft Academic Search

In this study we evaluate in vitro the cytotoxic activity of two newly synthesized phthalocyanines (metallo-complexes) with absorption bands in the red part of the spectrum: zinc-tri-sulphonated phthalocyanine (ZnS4Pc). Two permanent animal tumor cell lines are used in the experiments: LSR-SF(SR)-transplantable sarcoma in rat induced by Rous sarcoma virus strain Schmidt-Ruppin and LSCC-SF(Mc29)-transplantable chicken hepatoma induced by the myelocytomatosis virus

Radostina Alexandrova; Elena Stoykova; Rodica-Mariana Ion; Kristina Nedkova; Elena Ivanova; Kaloian Zdravkov; Georgi Minchev

2005-01-01

168

Enhanced reverse saturable absorption and optical limiting in heavy-atom-substituted phthalocyanines  

Microsoft Academic Search

The reverse saturable absorption and optical limiting response of metal phthalocyanines can be enhanced by using the heavy-atom effect. Phthalocyanines containing heavy metal atoms, such as In, Sn, and Pb show nearly a factor of two enhancement in the ratio of effective excited-state to ground-state absorption cross sections compared to those containing lighter atoms, such as Al and Si. In

Joseph W. Perry; Kamjou Mansour; Seth R. Marder; Kelly J. Perry; Daniel Alvarez Jr.; Ingrid Choong

1994-01-01

169

Spectrophotometric study of mercaptide ion-cobalt phthalocyanine-oxygen ternary system  

SciTech Connect

Cobalt(II) phthalocyanine undergoes a one-electron reduction by sodium mercaptide in a N,N-dimethylformamide medium under anaerobic conditions. A ternary complex of cobalt phthalocyanine with thiolate and oxygen is formed during contact with oxygen in the presence of excess thiolate ions. The complex has sensitivity to light and decomposes in the presence of aqueous alkali. The alternative possibility of a formation of a dithiolate derivative of cobalt(III) is less probable.

Kozlyak, E.I.; Erokhin, A.S.; Yatsimirskii, A.K.; Berezin, I.V.

1986-10-10

170

Synergistic effect of ultrasound and phthalocyanines on nucleated erythrocytes in vitro.  

PubMed

The synergistic effect of ultrasound (US) and chemicals on cells is known as sonodynamic therapy. In this work, two phthalocyanines (zinc and chloroaluminum) have been tested as potential sonosensitizers for sonodynamic therapy. We studied the effect of US and phthalocyanines on carp erythrocytes, as a nucleated cell model. The level of hemolysis, osmotic fragility, lipid peroxidation and oxidation of hemoglobin were the markers of these reactions. Red blood cells were preincubated with phthalocyanines and exposed to 1 MHz continuous wave at the intensity of 2.44 W/cm2 for 5 min. It was noticed that US and phthalocyanines exposure led to an increase in the level of hemolysis, lipid peroxidation product and osmotic fragility in comparison to US alone and phthalocyanines alone. However, these factors did not cause changes in the degree of hemoglobin oxidation. The results lead to the conclusion that phthalocyanines caused synergistic effect with US, and it can be used as a sonosensitizer for sonodynamic therapy, but the mechanism of this action is still unclear. PMID:16344133

Milowska, Katarzyna; Gabryelak, Teresa

2005-12-01

171

Electronic structure of iron phthalocyanine and its analogs: a theoretical study  

SciTech Connect

Molecular electronic structures of the dianions and iron complexes of phthalocyanine and other macrocyclic compounds (i.e., tetrabenzoporphyrin, tetrazaporphyrin and porphyrin) which are of interest in oxygen electrocatalysis have been calculated using CNDO/INDO molecular orbital methods. Significatn differences are found between the electron distributions in phthalocyanine and porphyrin due mainly to a difference in the nature of the atom bridging the indole and pyrrole ligands. Both iron complexes of phthalocyanine and porphyrin have a quintuplet molecular electronic ground state with iron in an intermediate spin state in the former and high spin in the latter. Binding of oxygen to the iron center in model compounds of iron phthalocyanine and iron porphyrin was studied. Side-on configuration appears to be preferred in the oxygen-phthalocyanine system and end-on bonding in the oxygen-porphyrin complex. The effect of catalyst support, electron delocalization by dimerization, and protons in solution on the oxygen binding by iron phthalocyanine was also examined and preliminary results are described. 2 figures, 3 tables.

Sabelli, N.H.; Lee, L.K.; Melendres, C.A.

1981-04-01

172

Phthalocyanines as photosensitizing agents for tumors--mechanism of action  

NASA Astrophysics Data System (ADS)

Aluminum phthalocyanine (AlPc) is a second-generation photosensitizer under study for photodynamic therapy (PDT) of cancer. Its mechanism of action is not known. Fluoride appears to be a powerful probe for the mechanistic study of AlPc derivatives. F- forms a complex with the Al ligand, resulting in drastically reduced AlPc-induced phototoxicity. This is due to a modified binding of AlPc with certain target proteins, resulting in inhibition of electron transfer reactions (type I) but not singlet oxygen reactions (type II). In Chinese hamster ovary (CHO) cell membranes, Na+/K+-ATPase activity is selectively protected by F- from photosensitized inhibition by AlPc, suggesting that this enzyme may be a critical target for AlPc-PDT. Another cellular response, not interfered with by F-, is a transient increase of cytoplasmic free Ca2+ after AlPc-PDT. This increase was shown to trigger the induction of a recovery process.

Ben-Hur, Ehud

1994-03-01

173

Correlation dependences in infrared spectra of metal phthalocyanines  

SciTech Connect

Metal-phthalocyanine (MPc) complexes CoPc, CuPc, CuPcCl{sub 15-16}, CuPc(4-NO{sub 2}-5-OPh){sub 4}, CuPc(4-CH{sub 2}-phthalimide){sub 4}, CuPc(4-NO{sub 2}-5-NHPhBr){sub 4}, PdPc, MgPc, PbPc, EuOAcPc, SmOAcPc, SmPc{sub 2}, and YOAcPc were obtained and studied using IR spectroscopy. The correlation between the shift of the absorption band maximum in the range of 1100-1600 cm{sup -1} and the atomic radius of template metal is found. It is shown that the planarity of the macrocycle of peripherally substituted CuPc can be estimated from the characteristics of the IR spectra.

Ziminov, A. V., E-mail: ziminov@yandex.ru; Ramsh, S. M. [Technical University, St. Petersburg Technological Institute (Russian Federation); Terukov, E. I.; Trapeznikova, I. N. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation); Shamanin, V. V. [Russian Academy of Sciences, Institute of Macromolecular Compounds (Russian Federation); Yurre, T. A. [Technical University, St. Petersburg Technological Institute (Russian Federation)

2006-10-15

174

Order on disorder: Copper phthalocyanine thin films on technical substrates  

SciTech Connect

We have studied the molecular orientation of the commonly used organic semiconductor copper phthalocyanine (CuPC) grown as thin films on the technically relevant substrates indium tin oxide, oxidized Si, and polycrystalline gold using polarization-dependent x-ray absorption spectroscopy, and compare the results with those obtained from single crystalline substrates [Au(110) and GeS(001)]. Surprisingly, the 20{endash}50 nm thick CuPC films on the technical substrates are as highly ordered as on the single crystals. Importantly, however, the molecular orientation in the two cases is radically different: the CuPC molecules stand on the technical substrates and lie on the single crystalline substrates. The reasons for this and its consequences for our understanding of the behavior of CuPC films in devices are discussed. {copyright} 2001 American Institute of Physics.

Peisert, H.; Schwieger, T.; Auerhammer, J. M.; Knupfer, M.; Golden, M. S.; Fink, J.; Bressler, P. R.; Mast, M.

2001-07-01

175

Magnetism and multiplets in Fe-phthalocyanine molecules  

NASA Astrophysics Data System (ADS)

Magnetism and multiplets for Fe-phthalocyanine molecules were investigated based on the constraint density functional theory (DFT) by imposing a density matrix constraint on the d-orbital occupation numbers. We demonstrate that for a single FePc molecule, there are three stationary states of multiplets, 3 E g , 3 A 2 g , and 3 B 2 g , and that the magnetic anisotropy (MA) strongly depends on the multiplet structures. The ground state of the 3 A 2 g obtained from the constraint DFT total energy calculations has planar MA, with the spin moments pointing along the molecule's planar direction. The columnar stacking structure for ?-FePc, with the ground state of the 3 E g , shows planar MA.

Kitaoka, Yukie; Nakamura, Kohji; Akiyama, Toru; Ito, Tomonori; Weinert, M.; Freeman, A. J.

2013-08-01

176

A Review on Composite Liposomal Technologies for Specialized Drug Delivery  

PubMed Central

The combination of liposomes with polymeric scaffolds could revolutionize the current state of drug delivery technology. Although liposomes have been extensively studied as a promising drug delivery model for bioactive compounds, there still remain major drawbacks for widespread pharmaceutical application. Two approaches for overcoming the factors related to the suboptimal efficacy of liposomes in drug delivery have been suggested. The first entails modifying the liposome surface with functional moieties, while the second involves integration of pre-encapsulated drug-loaded liposomes within depot polymeric scaffolds. This attempts to provide ingenious solutions to the limitations of conventional liposomes such as short plasma half-lives, toxicity, stability, and poor control of drug release over prolonged periods. This review delineates the key advances in composite technologies that merge the concepts of depot polymeric scaffolds with liposome technology to overcome the limitations of conventional liposomes for pharmaceutical applications.

Mufamadi, Maluta S.; Pillay, Viness; Choonara, Yahya E.; Du Toit, Lisa C.; Modi, Girish; Naidoo, Dinesh; Ndesendo, Valence M. K.

2011-01-01

177

Encapsulated liposomes for long-term drug delivery  

NSDL National Science Digital Library

Solve the steady-state radial diffusion equation in a sphere to calculate the resistance to drug diffusion through a liposome encapsulant; then compare to resistance to transport through the liposome membrane and determine the limiting step.

Powell, Adam C., IV

2004-08-11

178

Liposomal simvastatin attenuates neointimal hyperplasia in rats.  

PubMed

Monocytes, macrophages, and inflammation play a key role in the process of neointimal proliferation and restenosis. The present study evaluated whether systemic and transient depletion of monocytes could be obtained by a single intravenous (IV) injection of simvastatin liposomes, for the inhibition of neointima formation. Balloon-injured carotid artery rats (n = 30) were randomly assigned to treatment groups of free simvastatin, simvastatin in liposomes (3 mg/kg), and saline (control). Stenosis and neointima to media ratio (N/M) were determined 14 days following single IV injection at the time of injury by morphometric analysis. Depletion of circulating monocytes was determined by flow cytometry analyzes of blood specimens. Inhibition of RAW264.7, J774, and THP-1 proliferation by simvastatin-loaded liposomes and free simvastatin was determined by the 3-(4, 5-dimethylthiazolyl-2)-2, 5- diphenyltetrazolium bromide assay. Simvastatin liposomes were successfully formulated and were found to be 1.5-2 times more potent than the free drug in suppressing the proliferation of monocytes/macrophages in cell cultures of RAW 264.7, J774, and THP-1. IV injection of liposomal simvastatin to carotid-injured rats (3 mg/kg, n = 4) resulted in a transient depletion of circulating monocytes, significantly more prolonged than that observed following treatment with free simvastatin. Administration to balloon-injured rats suppressed neointimal growth. N/M at 14 days was 1.56 +/- 0.16 and 0.90 +/- 0.12, control and simvastatin liposomes, respectively. One single systemic administration of liposomal simvastatin at the time of injury significantly suppresses neointimal formation in the rat model of restenosis, mediated via a partial and transient depletion of circulating monocytes. PMID:20143196

Afergan, Eyal; Ben David, Meital; Epstein, Hila; Koroukhov, Nickolay; Gilhar, Dalia; Rohekar, Keren; Danenberg, Haim D; Golomb, Gershon

2010-02-09

179

Receptor-Targeting Phthalocyanine Photosensitizer for Improving Antitumor Photocytotoxicity  

PubMed Central

Photodynamic therapy (PDT) is a promising therapeutic modality which uses a photosensitizer to capture visible light resulting in phototoxicity in the irradiated region. PDT has been used in a number of pathological indications, including tumor. A key desirable feature of the photosensitizer is the high phototoxicity on tumor cells but not on normal cells. In this study, we conjugate a gonadotropin-releasing hormone (GnRH) to a photosensitizer, Zinc phthalocyanine (ZnPc), in order to enhance its specificity to breast cancer, which over-expresses GnRH receptor. ZnPc has unique advantages over other photosensitizers, but is difficult to derivatize and purify as a single isomer. We previously developed a straight-forward way to synthesize mono-substituted ?-carboxy-phthalocyanine zinc (ZnPc-COOH). Photophysical and photochemical parameters of this ZnPc-GnRH conjugate including fluorescence quantum yield (?f), fluorescence decay time (?s) and singlet oxygen quantum yield (??) were evaluated and found comparable with that of ZnPc, indicating that addition of a GnRH peptide does not significantly alter the generation of singlet oxygen from ZnPc. Cellular uptakes and phototoxicities of this conjugate were tested and found significantly enhanced on human breast cancer cell lines overexpressing GnRH receptors (MDA-MB-231 and MCF-7 cells) compared to cells with low levels of GnRH receptors, such as human embryonic lung fibroblast (HELF) and human liver carcinoma (HepG2) cells. In addition, the cellular uptake of this conjugate toward MCF-7 cells were found clearly alleviated by a GnRH receptor blocker Cetrorelix, suggesting that the cellular uptake of this conjugate was GnRH receptor-mediated. Put together, these findings revealed that coupling ZnPc with GnRH analogue was an effective way to improve the selectivity of ZnPc towards tumors with over-expressed GnRH receptors.

Xu, Peng; Chen, Jincan; Chen, Zhuo; Zhou, Shanyong; Hu, Ping; Chen, Xueyuan; Huang, Mingdong

2012-01-01

180

Liposome-mediated delivery of DNA to carrot protoplasts  

Microsoft Academic Search

The encapsulation of DNA within liposomes and subsequent fusion of the liposomes with carrot (Daucus carota L.) protoplasts were examined to determine optimum conditions for effective liposome-mediated delivery of DNA to protoplasts. Escherichia coli [3H]DNA could be encapsulated with 50% efficiency using encapsulation volumes as low as 0.5 ml. Incorporation of liposome-encapsulated [3H]DNA by carrot protoplasts increased linearly for 2.5

Benjamin F. Matthews; Dean E. Cress

1981-01-01

181

Characterisation of gene delivery using liposomal bubbles and ultrasound  

Microsoft Academic Search

The combination of nano\\/microbubbles and ultrasound is a novel technique for a non-viral gene deliver. We have previously developed novel ultrasound sensitive liposomes (Bubble liposomes) which contain the ultrasound imaging gas perfluoropropane. In this study, Bubble liposomes were compared with cationic lipid (CL)-DNA complexes as potential gene delivery carriers into tumors in vivo. The delivery of genes by bubble liposomes

Risa Koshima; Ryo Suzuki; Yusuke Oda; Keiichi Hirata; Tetsuya Nomura; Yoichi Negishi; Naoki Utoguchi; Nobuki Kudo; Kazuo Maruyama

2011-01-01

182

Interaction of liposome-encapsulated cisplatin with biomolecules.  

PubMed

We prepared liposomes by hydrating 1,2-dioleoyl-sn-glycero-3-phosphocholine lipid with aqueous solutions of three "probe" molecules-cis-diamminedichloroplatinum(II) (cis-[Pt(II)(NH(3))(2)Cl(2)], cisplatin), guanosine 5'-monophosphate (5'-GMP), and 9-ethylguanine (9-EtG)-in phosphate-buffered saline as well as N-(2-hydroxyethyl)piperazine-N'-ethanesulfonic acid buffer. The positively charged hydrolysis product of cisplatin, [Pt(II)(NH(3))(2)Cl(H(2)O)](+), is in the inner core of the liposomes and negatively charged 5'-GMP embeds in the lipid bilayer of liposomes. In the presence of cisplatin, the size of the liposomes remains unchanged, and for 5'-GMP-embedded liposomes the size increases significantly compared with that of empty or control liposomes. In contrast, the neutral biomolecule 9-EtG was found to be dispersed in the exterior bulk water and the size of the liposomes remained the same as that of empty or control liposomes. When cisplatin-containing liposomes mix with 5'-GMP-embedded liposomes or liposomes with 9-EtG, the N7 nitrogen atom of 5'-GMP or 9-EtG binds the cisplatin, thus replacing the "leaving groups" and forming a bisadduct. After 48 h of mixing, the size of the liposomes changes for the mixture of 5'-GMP-embedded liposomes and cisplatin-containing liposomes. We used (1)H and (31)P NMR spectroscopic techniques to monitor incorporation or association of cisplatin and biomolecules with liposomes and their subsequent reactions with each other. The dynamic light scattering technique provided the size distribution of the liposomes in the presence and absence of probe molecules. PMID:22674433

Baruah, Bharat; Surin, Alexandr

2012-06-07

183

Glucose-Sensitive Liposomes Incorporating Hydrophobically Modified Glucose Oxidase  

Microsoft Academic Search

Glucose-sensitive liposomes were prepared by incorporating hydrophobically modified glucose oxidase (EC 1.1.3.4.) into the\\u000a liposomal bilayer of dioleoylphosphatidylethanolamine and cholesteryl hemisuccinate. For the release test, calcein, a fluorescence\\u000a marker, was entrapped in the liposomes. The liposomes were stable under neutral conditions in terms of calcein release but\\u000a an extensive release was observed under acidic conditions. In the experiment of glucose

Seong-Min Jo; Hyeon Yong Lee; Jin-Chul Kim

2008-01-01

184

Immunogenicity of Liposomal Malaria Sporozoite Antigen in Monkeys: Adjuvant Effects of Aluminum Hydroxide and Non-Pyrogenic Liposomal Lipid A.  

National Technical Information Service (NTIS)

The immunogenicity of a recombinant protein containing sequences from the tetrapeptide repeat region of the circumsporozoite protein of Plasmodium falciparum was enhanced by encapsulation in liposomes containing lipid A and adsorption of the liposomes wit...

R. L. Richards G. M. Swartz C. Schultz M. D. Hayre G. S. Ward

1989-01-01

185

Recent advances in liposomal drug-delivery systems  

Microsoft Academic Search

Liposomal drug-delivery systems have come of age in recent years, with several liposomal drugs currently in advanced clinical trials or already on the market. It is clear from numerous pre-clinical and clinical studies that drugs, such as antitumor drugs, packaged in liposomes exhibit reduced toxicities, while retaining, or gaining enhanced, efficacy. This results, in part, from altered pharmacokinetics, which lead

Arcadio Chonn; Pieter R Cullis

1995-01-01

186

Liposomal prilocaine: preparation, characterization, and in vivo evaluation  

Microsoft Academic Search

PURPOSE. This study reports the develop- ment and in vivo evaluation of a liposomal system for the local anesthetic, prilocaine. METHODS. Liposomal prilocaine was prepared with egg phosphatidylcholine, cholesterol and ?-tocopherol (4:3:0.07 molar ratio). The size of the liposomes was measured by laser light scat- tering and the effect of prilocaine on membrane fluidity made use of electron spin resonance

Cíntia Maria Saia Cereda; Daniele Ribeiro De Araujo; Giovana Bruschini Brunetto; Eneida De Paula

2004-01-01

187

Photodegradation of Lecithin Liposomes by Nanoparticulate Titanium Dioxide  

Microsoft Academic Search

Lecithin liposomes were studied by transmission electron microscopy (TEM), selected?area electron diffraction (SAED), IR, and GC?MS. Results indicate that titanium dioxide (TiO2) nanoparticles can gain access into lecithin liposomes during sonication and the lecithin liposomes can be effectively decomposed upon illumination with near?UV light.

Aihua Zou; Qiang Gu; Jing Wang; Chunwei Yuan; Rong Guo

2003-01-01

188

The preparation and characterization of gas bubble containing liposomes  

Microsoft Academic Search

Liposomes and lipid nano-particles containing gas bubbles have great potentials to be used as ultrasound contrast agents or as drug and gene delivery vehicles. We developed a method to enable in situ CO2 gas bubbles formation inside liposomes. The resulted bubbles containing liposomes were shown to be able to effectively echo ultrasound. Their acoustic properties were assessed by ultrasound imaging

Rui Liu; Xiaohui Wei; Yanbin Yao; Qiliang Chai; Yue Chen; Yuhong Xu

2005-01-01

189

Sterically Stabilized Liposomes: Improvements in Pharmacokinetics and Antitumor Therapeutic Efficacy  

Microsoft Academic Search

The results obtained in this study establish that liposome formulations incorporating a synthetic polyethylene glycol-derivatized phospholipid have a pronounced effect on liposome tissue distribution and can produce a large increase in the pharmacological efficacy of encapsulated antitumor drugs. This effect is substantially greater than that observed previously with conventional liposomes and is associated with a more than 5-fold prolongation of

D. Papahadjopoulos; T. M. Allen; A. Gabizon; E. Mayhew; K. Matthay; S. K. Huang; K.-D. Lee; M. C. Woodle; D. D. Lasic; C. Redemann; F. J. Martin

1991-01-01

190

Adhesion of liposomes: a quartz crystal microbalance study  

Microsoft Academic Search

Three different systems are presented, exploring the adhesion of liposomes mediated by electrostatic and lipid-protein interactions as well as molecular recognition of ligand receptor pairs. Liposomes are frequently used to gain insight into the complicated processes involving adhesion and subsequent events such as fusion and fission mainly triggered by specific proteins. We combined liposome technology with the quartz crystal microbalance

Eike Lüthgens; Alexander Herrig; Katja Kastl; Claudia Steinem; Björn Reiss; Joachim Wegener; Bruno Pignataro; Andreas Janshoff

2003-01-01

191

Antileishmanial Activity of Liposomal Clarithromycin against Leishmania Major Promastigotes  

PubMed Central

Objective(s) Cutaneous leishmaniasis is a common parasitic disease which is endemic in some parts of the world. In vitro and in vivo studies have shown azithromycin efficacy on some Leishmania species. Because of structural similarity between clarithromycin and azithromycin and efficacy of clarithromycin against intracellular organisms and due to the absence of previous studies in this respect, we decided to evaluate the efficacy of clarithromycin against promastigotes of L. major in vitro. Materials and Method First, liposomal and non- liposomal clarithromycin were prepared, then both forms of the drug were incubated with promastigotes for 24 hr in NNN culture media without red phenol in the presence of 5% FCS with different concentrations as follows: 20, 40, 80, 100, 200 and 500 µg/ml. Results According to the results, clarithromycin in both liposomal and non- liposomal forms has in vitro activity against the promastigotes of L. major. The concentration of drug that killed 50% of parasites (ED 50) was 169 and 253.6 µg/ml for liposomal and non- liposomal forms, respectively which shows that lower concentrations of liposomal drug are required to have the same effect as non- liposomal drug and the liposomal form of the drug is more effective than non- liposomal form. Conclusion Clarithromycin in both liposomal and non- liposomal forms has in vitro activity against the promastigotes of L. major.

Sazgarnia, Ameneh; Zabolinejad, Naghmeh; Layegh, Pouran; Rajabi, Omid; Berenji, Fariba; Javidi, Zari; Salari, Roshanak

2012-01-01

192

Remotely controlled diffusion from magnetic liposome microgels.  

PubMed

The reversible, temperature-dependent change in the permeability of a phospholipid bilayer has been used for controlling the diffusion rate of encapsulated molecular payload from liposomes. Liposomes were preloaded with a fluorescent dye and immobilized in calcium alginate hydrogel microparticles that also contained iron oxide nanoparticles. The composite microparticles were produced by a drop-on-demand inkjet method. The ability of iron oxide nanoparticles to locally dissipate heat upon exposure to a radio-frequency (RF) alternating magnetic field was used to control the local temperature and therefore diffusion from the liposomes in a contactless way using an RF coil. Several different release patterns were realized, including repeated on-demand release. The internal structure of the composite alginate-liposome-magnetite microparticles was investigated, and the influence of microparticle concentration on the heating rate was determined. In order to achieve a temperature rise required for the liposome membrane melting, the concentration of alginate beads should be at least 25% of their maximum packing density for the nanoparticle concentration and specific absorption rate used. PMID:23461732

Hanuš, Jaroslav; Ullrich, Martin; Dohnal, Ji?í; Singh, Mandeep; St?pánek, František

2013-03-18

193

A novel liposomal formulation of flavopiridol.  

PubMed

Flavopiridol has shown promising activities in hematologic and solid tumor models, as well as in clinical trials in chronic lymphocytic leukemia patients. Flavopiridol has relatively low solubility and high plasma protein-binding. To address these issues and to provide an alternative strategy to achieve clinical efficacy, we encapsulated flavopiridol into a liposomal carrier and characterized its physicochemical and pharmacokinetic properties. The liposomes, comprising hydrogenated soy phosphatidylcholine (HSPC), cholesterol and poly (ethylene glycol) 2000-distearoyl phosphatidylethanolamine (PEG-DSPE), were prepared by polycarbonate membrane extrusion and then loaded with flavopiridol by a pH-gradient driven remote loading procedure. The liposomes had a mean diameter of 120.7 nm and a flavopiridol entrapment efficiency of 70.4%. Pharmacokinetic study in mice after i.v. bolus injection showed that the liposomal flavopiridol had an increased elimination phase half-life (T((1/2)beta), 339.7 min vs. 57.0 min), decreased clearance (CL, 0.012 L/min vs. 0.036 L/min), and increased area under the plasma concentration-time curve (AUC, 10.8 min micromol/L vs. 3.4 min micromol/L) compared to the free drug. This indicates a significant and potentially beneficial change in flavopiridol pharmacokinetics for the liposomal formulation. Further preclinical studies are warranted to define the toxicity and therapeutic efficacy of this novel formulation. PMID:18778761

Yang, Xiaojuan; Zhao, Xiaobin; Phelps, Mitch A; Piao, Longzhu; Rozewski, Darlene M; Liu, Qing; Lee, L James; Marcucci, Guido; Grever, Michael R; Byrd, John C; Dalton, James T; Lee, Robert J

2008-08-20

194

A novel liposomal formulation of flavopiridol  

PubMed Central

Flavopiridol has shown promising activities in hematologic and solid tumor models, as well as in clinical trials in chronic lymphocytic leukemia patients. Flavopiridol has relatively low solubility and high plasma protein-binding. To address these issues and to provide an alternative strategy to achieve clinical efficacy, we encapsulated flavopiridol into a liposomal carrier and characterized its physicochemical and pharmacokinetic properties. The liposomes, comprising hydrogenated soy phosphatidylcholine (HSPC), cholesterol and poly (ethylene glycol) 2000-distearoyl phosphatidylethanolamine (PEG-DSPE), were prepared by polycarbonate membrane extrusion and then loaded with flavopiridol by a pH-gradient driven remote loading procedure. The liposomes had a mean diameter of 120.7 nm and a flavopiridol entrapment efficiency of 70.4%. Pharmacokinetic study in mice after i.v. bolus injection showed that the liposomal flavopiridol had an increased elimination phase half-life (T1/2?, 339.7 min vs. 57.0 min), decreased clearance (CL, 0.012 L/min vs. 0.036 L/min), and increased area under the plasma concentration–time curve (AUC, 10.8 min ?mol/L vs. 3.4 min ?mol/L) compared to the free drug. This indicates a significant and potentially beneficial change in flavopiridol pharmacokinetics for the liposomal formulation. Further preclinical studies are warranted to define the toxicity and therapeutic efficacy of this novel formulation.

Yang, Xiaojuan; Zhao, Xiaobin; Phelps, Mitch A.; Piao, Longzhu; Rozewski, Darlene M.; Liu, Qing; Lee, L. James; Marcucci, Guido; Grever, Michael R.; Byrd, John C.; Dalton, James T.; Lee, Robert J.

2011-01-01

195

Liposomal Encapsulated Rhodomyrtone: A Novel Antiacne Drug  

PubMed Central

Rhodomyrtone isolated from the leaves of Rhodomyrtus tomentosa possesses antibacterial, anti-inflammatory, and anti-oxidant activities. Since rhodomyrtone is insoluble in water, it is rather difficult to get to the target sites in human body. Liposome exhibited ability to entrap both hydrophilic and hydrophobic compounds and easily penetrate to the target site. The present study aimed to develop a novel liposomal encapsulated rhodomyrtone formulations. In addition, characterization of liposome, stability profiles, and their antiacne activity were performed. Three different formulations of total lipid concentrations 60, 80, and 100??mol/mL were used. Formulation with 60??mol/mL total lipid (phosphatidylcholine from soybean and cholesterol from lanolin in 4?:?1, w/w) exhibited the highest rhodomyrtone encapsulation efficacy (65.47 ± 1.7%), average particle size (209.56 ± 4.8?nm), and ?-potential (–41.19 ± 1.3?mV). All formulations demonstrated good stability when stored for 2 months in dark at 4°C as well as room temperature. Minimal inhibitory concentration and minimal bactericidal concentration values of liposomal formulation against 11 clinical bacterial isolates and reference strains ranged from 1 to 4 and from 4 to 64??g/mL, respectively, while those of rhodomyrtone were 0.25–1 and 0.5–2??g/mL, respectively. The MIC and MBC values of liposome formulation were more effective than topical drugs against Staphylococcus aureus and Staphylococcus epidermidis.

Chorachoo, Julalak; Amnuaikit, Thanaporn; Voravuthikunchai, Supayang P.

2013-01-01

196

Miniaturized bioanalytical systems: enhanced performance through liposomes.  

PubMed

Biorecognition-element labeled liposomes are simple and versatile tools used to amplify signals for the detection of analytes of environmental, clinical, food safety, and national security interest. Relying on measurement of encapsulated species via electrochemical or spectroscopic techniques, or properties inherent to liposomes themselves (such as mass, refractive index, or charge), many advances have been made in both bench-scale and microfluidic applications. Some of these measurement techniques are inherently sensitivity limited, but through the inclusion of liposomes, reduced limits of detection potentially broaden the utility towards otherwise challenging levels of analytes. Other advances took advantage of the hydrophobic environment required by many biorecognition elements to expand the target selectivity range or utilized the amphipathic nature of the lipid bilayer to provide enhanced separation capabilities. Novel handling approaches included wavelength-specific release of contents encapsulated within thermosensitive liposomes or application of electric fields to move, concentrate, and strategically lyse liposomes. These and other topics are discussed in terms of either present incorporation or adaptation to microfluidic devices. PMID:22673065

Edwards, Katie A; Bolduc, Olivier R; Baeumner, Antje J

2012-06-04

197

Simultaneous Production of Superoxide Radical and Singlet Oxygen by Sulphonated Chloroaluminum Phthalocyanine Incorporated in Human Low-density Lipoproteins: Implications for Photodynamic Therapy¶  

Microsoft Academic Search

Sulfonated chloroaluminum phthalocyanines have been studied for their use in the photodynamic therapy (PDT) of tumors. Plasma low-density lipoproteins (LDL) are important carriers of phthalocyanines in the blood, but on exposure to visible light, phthalocyanine-loaded LDL undergo an oxida- tion process that propagates to erythrocytes. We attempted to identify the reactive species involved in LDL and erythrocyte oxidation by means

Joana Martins; Leonor Almeida; João Laranjinha

2004-01-01

198

Observation of Outermost Surface Layers of Phthalocyanine Ultra-Thin Films by Penning Ionization Electron Spectroscopy: Chloroaluminium Phthalocyanine on MoS2  

Microsoft Academic Search

Using Penning ionization electron spectroscopy, which provides information on the local distribution of the individual orbitals exposed outside the outermost surface layer, ultra-thin films (1 to several monolayers) of chloroaluminium phthalocyanine were characterized during layer-by-layer vacuum deposition onto an MoS2 substrate and the change in the molecular orientation was sensitively detected.

Masaru Aoki; Shigeru Masuda; Yuichi Einaga; Koji Kamiya; Nobuo Ueno; Yoshiya Harada

1995-01-01

199

Liposomal boron delivery for neutron capture therapy.  

PubMed

Tumor cell destruction in boron neutron capture therapy (BNCT) is due to the nuclear reaction between (10)B and thermal neutrons. The thermal neutrons have an energy of 0.025 eV, clearly below the threshold energy required to ionize tissue components. However, neutron capture by (10)B produces lithium ion and helium (alpha-particles), which are high linear energy transfer (LET) particles, and dissipate their kinetic energy before traveling one cell diameter (5-9 microm) in biological tissues, ensuring their potential for precise cell killing. BNCT has been applied clinically for the treatment of malignant brain tumors, malignant melanoma, head and neck cancer, and hepatoma using two boron compounds: sodium borocaptate (Na(2)(10)B(12)H(11)SH; Na(2)(10)BSH) and l-p-boronophenylalanine (l-(10)BPA). These low molecular weight compounds are cleared easily from the cancer cells and blood. Therefore, high accumulation and selective delivery of boron compounds into tumor tissues are most important to achieve effective BNCT and to avoid damage of adjacent healthy cells. Much attention has been focused on the liposomal drug delivery system (DDS) as an attractive, intelligent technology of targeting and controlled release of (10)B compounds. Two approaches have been investigated for incorporation of (10)B into liposomes: (1) encapsulation of (10)B compounds into liposomes and (2) incorporation of (10)B-conjugated lipids into the liposomal bilayer. Our laboratory has developed boron ion cluster lipids for application of the latter approach. In this chapter, our boron lipid liposome approaches as well as recent developments of the liposomal boron delivery system are summarized. PMID:19913168

Nakamura, Hiroyuki

2009-01-01

200

Method of encapsulating polyaminopolycarboxylic acid chelating agents in liposomes  

DOEpatents

A method is provided for transferring a polyaminopolycarboxylic acid chelating agent across a cellular membrane by encapsulating the charged chelating agent within liposomes, which liposomes will be taken up by the cells, thereby transferring the chelating agent across the cellular membrane. The chelating agent is encapsulated within liposomes by drying a lipid mixture to form a thin film and wetting the lipid film with a solution containing the chelating agent. Mixing then results in the formation of a suspension of liposomes encapsulating the chelating agent, which liposomes can then be separated.

Rahman, Yueh Erh (Downers Grove, IL)

1977-11-10

201

Application of liposomes in drug development -- focus on gastroenterological targets  

PubMed Central

Over the past decade, liposomes became a focal point in developing drug delivery systems. New liposomes, with novel lipid molecules or conjugates, and new formulations opened possibilities for safely and efficiently treating many diseases including cancers. New types of liposomes can prolong circulation time or specifically deliver drugs to therapeutic targets. This article concentrates on current developments in liposome based drug delivery systems for treating diseases of the gastrointestinal tract. We will review different types and uses of liposomes in the development of therapeutics for gastrointestinal diseases including inflammatory bowel diseases and colorectal cancer.

Zhang, Jian-Xin; Wang, Kun; Mao, Zheng-Fa; Fan, Xin; Jiang, De-Li; Chen, Min; Cui, Lei; Sun, Kang; Dang, Sheng-Chun

2013-01-01

202

Mechanical properties of a giant liposome studied using optical tweezers  

NASA Astrophysics Data System (ADS)

The mechanical properties of a micrometer-sized giant liposome are studied by deforming it from the inside using dual-beam optical tweezers. As the liposome is extended, its shape changes from a sphere to a lemon shape, and finally, a tubular part is generated. The surface tension ? and the bending rigidity ? of the lipid membrane are obtained from the measured force-extension curve. In a one-phase liposome, it was found that ? increases as the charged component increases but ? remains approximately constant. In a two-phase liposome, the characteristic deformation and the force-extension curve differ from those observed for the one-phase liposome.

Shitamichi, Yoko; Ichikawa, Masatoshi; Kimura, Yasuyuki

2009-09-01

203

Study of the stabilization of zinc phthalocyanine in sol-gel TiO 2 for photodynamic therapy applications  

Microsoft Academic Search

Photodynamic therapy (PDT) has emerged as an alternative and promising noninvasive treatment for cancer. It is a two-step procedure that uses a combination of molecular oxygen, visible light, and photosensitizer (PS) agents; phthalocyanine (Pc) was supported over titanium oxide but has not yet been used for cell inactivation. Zinc phthalocyanine (ZnPc) molecules were incorporated into the porous network of titanium

Tessy Lopez; Ema Ortiz; Mayra Alvarez; Juan Navarrete; Jose A. Odriozola; Fernando Martinez-Ortega; Edgar A. Páez-Mozo; Patricia Escobar; Karla A. Espinoza; Ignacio A. Rivero

2010-01-01

204

Efficacy of Liposomal Monensin on the Enhancement of the Antitumour Activity of Liposomal Ricin in Human Epidermoid Carcinoma (KB) Cells  

PubMed Central

The monensin, known to enhance the cytotoxicity of ricin and ricin-based immunotoxins is a very hydrophobic molecule and this limits its administration in optimum doses under in vivo conditions. In order to realise its full potential, monensin was intercalated into various liposomal formulations and its ability to potentiate the cytotoxicity of ricin liposomes in human epidermoid carcinoma (KB) cells was studied. It was observed that ricin cytotoxicity enhancing ability of monensin liposome depends on the surface charge as well as density and chain length of distearoyl phosphatidylethanolamine-methoxy polyethylene glycol present on the surface of liposomal monensin. Maximum potentiation on the cytotoxicity of liposomal ricin was observed by monensin entrapped in neutral liposome (106.5 fold) followed by negatively charged (94.2 fold) and positively charged liposome (90 fold). Studies on the effect of variation of density and chain length of distearoyl phosphatidylethanolamine-methoxy polyethylene glycol showed that neutral monensin liposomes having 2.5 mol% distearoyl phosphatidylethanolamine-methoxy polyethylene glycol with chain length of 2000 exhibits maximum potentiation (117.6 fold) on the cytotoxicity of ricin liposomes when the cellular uptake of monensin liposome was maximum (42.0%) and the zeta potential value on the surface of liposomes was ?0.645. The present study has clearly shown that liposomal monensin is very effective in enhancing the cytotoxicity of liposomal ricin in human cancer cells and liposome can be used as in vivo deliver vehicle for monensin to potentiate the cytotoxicity of liposomal ricin to eliminate cancer cells.

Tyagi, N.; Rathore, S. S.; Ghosh, P. C.

2013-01-01

205

Electronic Structure of C60/Phthalocyanine/ITO Interfaces Studied using Soft X-ray Spectroscopies  

SciTech Connect

The interface electronic structure of a bilayer heterojunction of C{sub 60} and three different phthalocyanines grown on indium tin oxide (ITO) has been studied using synchrotron radiation-excited photoelectron spectroscopy. The energy difference between the highest occupied molecular orbital level of the phthalocyanine (donor) layer and the lowest unoccupied molecular orbital level of the C{sub 60} (acceptor) layer (E{sub HOMO}{sup D} - E{sub LUMO}{sup A}) was determined. The E{sub HOMO}{sup D} - E{sub LUMO}{sup A} of a heterojunction with boron subphthalocyanine chloride (SubPc) was found to be much larger than those of copper phthalocyanine (CuPc) and chloro-aluminum phthalocyanine (ClAlPc). This observation is discussed in terms of the difference of the ionization energy of each donor material. Additionally, we have studied the molecular orientation of the phthalocyanine films on ITO using angle-dependent X-ray absorption spectroscopy. We found that the SubPc films showed significant disorder compared to the CuPc and ClAlPc films and also found that E{sub HOMO}{sup D} - E{sub LUMO}{sup A} varied with the orientation of the ClAlPc molecules relative to the ITO substrate. This orientation could be controlled by varying the ClAlPc deposition rate.

Cho, S.; Piper, L; DeMasi, A; Preston, A; Smith, K; Chauhan, K; Sullivan, P; Hatton, R; Jones, T

2010-01-01

206

Zinc phthalocyanine thin film and chemical analyte interaction studies by density functional theory and vibrational techniques.  

PubMed

Thin films of zinc phthalocyanine have been deposited on KBr and glass substrates by the thermal evaporation method and characterized by the x-ray diffraction, optical, infrared and Raman techniques. The observed x-ray diffraction and infrared absorption spectra of as-deposited thin films suggest the presence of an ? crystalline phase. Infrared and Raman spectra of thin films after exposure to vapours of ammonia and methanol have also been recorded. Shifts in the position of some IR and Raman bands in the spectra of exposed films have been observed. Some bands also show changes in their intensity on exposure. Increased charge on the phthalocyanine ring and out-of-plane distortion of the core due to interaction between zinc phthalocyanine and vapour molecules involving the fifth coordination site of the central metal ion may be responsible for the band shifts. Changes in the intensity of bands are interpreted in terms of the lowering of molecular symmetry from D(4h) to C(4v) due to doming of the core. Molecular parameters and Mulliken atomic charges of zinc phthalocyanine and its complexes with methanol and ammonia have been calculated from density functional theory. The binding energy of the complexes have also been calculated. Calculated values of the energy for different complexes suggest that axially coordinated vapour molecules form the most stable complex. Calculated Mulliken atomic charges show net charge transfer from vapour molecules to the phthalocyanine ring for the most stable complex. PMID:21715770

Saini, G S S; Singh, Sukhwinder; Kaur, Sarvpreet; Kumar, Ranjan; Sathe, Vasant; Tripathi, S K

2009-05-11

207

Antibacterial effect of cationic porphyrazines and anionic phthalocyanine and their interaction with plasmid DNA  

NASA Astrophysics Data System (ADS)

Resistance to antibiotics is a public health issue and identification of new antibacterial agents is one of the most important goals of pharmacological research. Among the novel developed antibacterial agents, porphyrin complexes and their derivatives are ideal candidates for use in medical applications. Phthalocyanines differ from porphyrins by having nitrogen atoms link the individual pyrrol units. The aza analogues of the phthalocyanines (azaPcs) such as tetramethylmetalloporphyrazines are heterocyclic Pc analogues. In this investigation, interaction of an anionic phthalocyanine (Cu(PcTs)) and two cationic tetrapyridinoporphyrazines including [Cu(2,3-tmtppa)]4+ and [Cu(3,4-tmtppa)]4+ complexes with plasmid DNA was studied using spectroscopic and gel electrophoresis methods. In addition, antibacterial effect of the complexes against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria was investigated using dilution test method. The results indicated that both porphyrazines have significant antibacterial properties, but Cu(PcTs) has weak antibacterial effect. Compairing the binding of the phthalocyanine and the porphyrazines to DNA demonstrated that the interaction of cationic porphyrazines is stronger than the anionic phthalocyanine remarkably. The extent of hypochromicity and red shift of absorption spectra indicated preferential intercalation of the two porphyrazine into the base pairs of DNA helix. Gel electrophoresis result implied Cu(2,3-tmtppa) and Cu(3,4-tmtppa) are able to perform cleavage of the plasmid DNA. Consequently, DNA binding and cleavage might be one of the antibacterial mechanisms of the complexes.

Hassani, Leila; Hakimian, Fatemeh; Safaei, Elham; Fazeli, Zahra

2013-11-01

208

Characterisation of gene delivery using liposomal bubbles and ultrasound  

NASA Astrophysics Data System (ADS)

The combination of nano/microbubbles and ultrasound is a novel technique for a non-viral gene deliver. We have previously developed novel ultrasound sensitive liposomes (Bubble liposomes) which contain the ultrasound imaging gas perfluoropropane. In this study, Bubble liposomes were compared with cationic lipid (CL)-DNA complexes as potential gene delivery carriers into tumors in vivo. The delivery of genes by bubble liposomes depended on the intensity of the applied ultrasound. The transfection efficiency plateaued at 0.7 W/cm2 ultrasound intensity. Bubble liposomes efficiently transferred genes into cultured cells even when the cells were exposed to ultrasound for only 1 s. In addition, bubble liposomes were able to introduce the luciferase gene more effectively than CL-DNA complexes into mouse ascites tumor cells. We conclude that the combination of Bubble liposomes and ultrasound is a good method for gene transfer in vivo.

Koshima, Risa; Suzuki, Ryo; Oda, Yusuke; Hirata, Keiichi; Nomura, Tetsuya; Negishi, Yoichi; Utoguchi, Naoki; Kudo, Nobuki; Maruyama, Kazuo

2011-09-01

209

Preparation of novel apigenin-enriched, liposomal and non-liposomal, antiinflammatory topical formulations as substitutes for corticosteroid therapy.  

PubMed

Two oil-in-water formulations, containing equal amounts of apigenin-enriched chamomile flower extracts, for potential use as topical antiinflammatory agents, were prepared and their physicochemical properties evaluated. A pilot clinical study was then carried out to assess patient acceptability and efficacy. The creams were either non-liposomal or liposomal. The liposomal formulations were more viscous, thus producing superior release characteristics in vitro. The clinical study also showed that the liposomal creams were, as antiinflammatory agents, slightly more effective in vivo than the non-liposomal formulations. These results suggest that there is scope for the further development of even more effective and safer alternatives to corticosteroids. PMID:20641055

Arsi?, Ivana; Tadi?, Vanja; Vlaovi?, Djordje; Homšek, Irena; Vesi?, Sonja; Isailovi?, Gorana; Vuleta, Gordana

2011-02-01

210

Electronic structure of cobalt phthalocyanine: A charge density study  

SciTech Connect

A charge density study of cobalt(II) phthalocyanine based upon 12,163 unique reflections within a (sin /theta/)//lambda/ range 0-10.8 nm/sup /minus/1/, collected by X-ray diffraction at 115 K, was performed. The data was modeled by a conventional multipole analysis as well as by a valence orbital population analysis. When the latter approach was used and data was employed to a (sin /theta/)//lambda/ limit of 8.2 nm/sup /minus/1/, a value of 0.031 was obtained for R/sub w/(I) and 0.015 for R(F). The deformation density maps show bond-centered peaks and lone-pair peaks of ca. 500 e nm/sup /minus/3/ within the phthalocyanine ligand molecule, such as are typical of most good light-atom charge density studies. The rearrangement of the electron density around the cobalt atom is substantial, both in angular function and in radial extent, and suggests a depletion and contraction of the 3d orbitals, combined with a population of more diffuse cobalt-based functions. The valence orbital population analysis quantifies the suggestion, giving a total 3d population of 4.9 (1)e with a radius reduced 35% from the free ion value and a diffuse population (modeled as 4p) of 2.6 (1)e. Those populations are strongly anisotropic: 3d/sub x/sup 2/-y/sup 2///sup 0.0/3d/sub xz,yz//sup 2.4/3d/sub z/sup 2///sup 0.8/3d/sub xy//sup 1.8/4p/sub z//sup 1.1/4p/sub xy//sup 1.4/. There seems to be little charge flow from the ligand to the metal atom (0.5 (1)e), but the bonding is obviously quite covalent in character. This is manifest in the distribution of charge between the 3d /pi/ and /sigma/ systems and the diffuse outer regions of the cobalt atom.

Figgis, B.N.; Kucharski, E.S.; Reynolds, P.A.

1989-03-01

211

Liposomal membranes. XIV. Fusion of liposomal membranes induced by polyisoprenoids as monitored by fluorescence quenching method.  

PubMed

Fusion of the single-walled liposomes of egg phosphatidylcholine as induced by the polyisoprenoids such as solanesol, trans-ethyl decaprenoate (EDP), coenzyme Q10, and dolichol has been investigated adopting the fluorescence quenching method. Relative efficiency of the polyisoprenoids employed on the induced fusion of liposomes was a sequence of solanesol less than or equal to EDP much less than CoQ10, dolichol, which was consistent with the result previously obtained by the dye-release method. PMID:6627530

Sunamoto, J; Iwamoto, K; Tezuka, T; Kadosaki, K; Kondo, H

1983-08-01

212

Amphiphilic polymer–liposome interaction: a novel immobilization technique for liposome on gel surface  

Microsoft Academic Search

We developed a simple method for the immobilization of liposomes and biological membrane fragments to gel surface using an amphiphilic polymer, consisting of octadecylacrylamide and N,N-dimethylacrylamide with a molar ratio of 99:1. Calcein-entrapped egg phosphatidylcholine liposomes were successfully immobilized to the surface of polyacrylamide gel containing the polymer without significant loss of entrapped calcein. Different contents of the amphiphilic polymer

Masayuki Hara; Huiqing Yuan; Masao Miyake; Sadayo Iijima; Qing Yang; Jun Miyake

2000-01-01

213

Preparation, characterization, and efficient transfection of cationic liposomes and nanomagnetic cationic liposomes  

PubMed Central

Purpose Cationic liposomes (CLs) are composed of phospholipid bilayers. One of the most important applications of these particles is in drug and gene delivery. However, using CLs to deliver therapeutic nucleic acids and drugs to target organs has some problems, including low transfection efficiency in vivo. The aim of this study was to develop novel CLs containing magnetite to overcome the deficiencies. Materials and methods CLs and magnetic cationic liposomes (MCLs) were prepared using the freeze-dried empty liposome method. Luciferase-harboring vectors (pGL3) were transferred into liposomes and the transfection efficiencies were determined by luciferase assay. Firefly luciferase is one of most popular reporter genes often used to measure the efficiency of gene transfer in vivo and in vitro. Different formulations of liposomes have been used for delivery of different kinds of gene reporters. Lipoplex (liposome–plasmid DNA complexes) formation was monitored by gel retardation assay. Size and charge of lipoplexes were determined using particle size analysis. Chinese hamster ovary cells were transfected by lipoplexes (liposome-pGL3); transfection efficiency and gene expression level was evaluated by luciferase assay. Results High transfection efficiency of plasmid by CLs and novel nanomagnetic CLs was achieved. Moreover, lipoplexes showed less cytotoxicity than polyethyleneimine and Lipofectamine™. Conclusion Novel liposome compositions (1,2-dipalmitoyl-sn-glycero-3-phosphocholine [DPPC]/dioctadecyldimethylammonium bromide [DOAB] and DPPC/cholesterol/DOAB) with high transfection efficiency can be useful in gene delivery in vitro. MCLs can also be used for targeted gene delivery, due to magnetic characteristic for conduction of genes or drugs to target organs.

Samadikhah, Hamid Reza; Majidi, Asia; Nikkhah, Maryam; Hosseinkhani, Saman

2011-01-01

214

Development of Liposomal Bubbles with Perfluoropropane Gas as Gene Delivery Carriers  

Microsoft Academic Search

Liposomes have some advantages as drug, antigen and gene delivery carriers. Their size can be easily controlled and they can be modified to add a targeting function. Based on liposome technology, we developed novel liposomal bubbles (Bubble liposomes) containing the ultrasound imaging gas, perfluoropropane. We assessed the feasibility of Bubble liposomes as carriers for gene delivery after cavitation induced by

Kazuo Maruyama; Ryo Suzuki; Kaori Sawamura; Tomoko Takizawa; Naoki Utoguchi; Yoichi Negishi

2007-01-01

215

Liposome Characterization by Quartz Crystal Microbalance Measurements and Atomic Force Microscopy  

Microsoft Academic Search

This chapter reviews liposome characterization by quartz crystal microbalance (QCM) measurements and atomic force microscopy (AFM). In many studies, AFM imaging is simply used to image liposomes with resolution often that does not allow morphological analysis. Although liposome size can be obtained by processing AFM images, it is found that liposomes flatten upon surface adsorption or immobilization. Liposome stability and

Patrick Vermette

2009-01-01

216

Investigations of a new, highly negative liposome with improved biodistribution for imaging  

Microsoft Academic Search

An attractive feature of liposomes is the wide range of lipid composition that can lead to liposome formation, coupled with the observation that liposome biodistribution may be altered by varying lipid composition. For instance, adding charged lipids to neutral lecithin will alter the biodistribution of the resulting charged liposomes. We have prepared highly negative liposomes by replacing lecithin with negatively

D. J. Hnatowich; B. Clancy

1980-01-01

217

Chromenone 12-crown-4 substituted zinc phthalocyanine complexes: investigation of spectral, photophysical and photochemical properties.  

PubMed

The synthesis of novel 6,7-[(12-crown-4)-3-[p-(3,4-dicyanophenoxy)phenyl]coumarin (1), 6,7-[(12-crown-4)-3-[p-(2,3-dicyanophenoxy)phenyl]coumarin (2), and their corresponding tetra-(chromenone 12-crown-4)-substituted zinc (II) phthalocyanine complexes (3 and 4) have been prepared. These new compounds have been characterized by elementel analysis, (1)H NMR (1 and 2), MALDI-TOF, IR and UV-Vis spectral data. The fluorescence intensity changes for 1 and 2 by addition of Na(+) or K(+) ions have been determined at 25°C in THF. Intensity of the binding Na(+)- and K(+)-complexes (1 and 2) have decreased. The effects of the chromenone crown ether on the phthalocyanine molecule concerning photophysical and photochemical properties are also investigated. Photodegredation, singlet oxygen, fluorescence quantum yields, and fluorescence lifetimes of zinc phthalocyanine complexes (3 and 4) are also examined in DMSO. PMID:21795111

Esenp?nar, Aliye Asl?; Durmu?, Mahmut; Bulut, Mustafa

2011-07-07

218

Triggerable plasmalogen liposomes: improvement of system efficiency  

Microsoft Academic Search

A photoactivated liposome release system that is generally applicable for triggered release of encapsulated hydrophilic materials is described. This approach to phototriggered release, derived from the known effects of plasmalogen photooxidation on membrane permeability in whole cells and model membrane systems, relies on producing a lamellar phase change or increase in permeability upon cleaving its constitutive lipids to single-chain surfactants

David H. Thompson; Oleg V. Gerasimov; Jefferey J. Wheeler; Yuanjin Rui; Valerie C. Anderson

1996-01-01

219

Fusion of Liposomes with Mitochondrial Inner Membranes  

NASA Astrophysics Data System (ADS)

A procedure is outlined for the fusion of mixed phospholipid liposomes (small unilamellar vesicles) with the mitochondrial inner membrane, which enriches the membrane lipid bilayer 30-700% in a controlled fashion. Fusion was initiated by manipulation of the pH of a mixture of freshly sonicated liposomes and the functional inner membrane/matrix fraction of rat liver mitochondria. During the pH fusion procedure, liposomes became closely apposed with and sequestered by the inner membranes as revealed by freeze-fracture electron microscopy. After the pH fusion procedure, a number of ultrastructural, compositional, and functional characteristics were found to be proportionally related: the membrane surface area increased; the lateral density distribution of intramembrane particles (integral proteins) in the plane of the membrane decreased whereas the particles remained random; the membrane became more buoyant; the ratio of membrane lipid phosphorus to total membrane protein increased; the ratio of membrane lipid phosphorus to heme a of cytochrome c oxidase increased; and the rate of electron transfer between some interacting membrane oxidoreduction proteins decreased. These data reveal that liposomal phospholipid was incorporated into the membrane bilayer (not simply adsorbed to the membrane surface) and that integral membrane proteins diffused freely into the laterally expanding bilayer. Furthermore, the data suggest that the rate of electron transfer may be limited by the rate of lateral diffusion of oxidoreduction components in the bilayer of the mitochondrial inner membrane.

Schneider, Heinz; Lemasters, John J.; Hochli, Matthias; Hackenbrock, Charles R.

1980-01-01

220

Theoretical investigation of nitric oxide interaction with aluminum phthalocyanine.  

PubMed

Nitric oxide (NO) is an extremely toxic compound formed during combustion, predominantly at high temperatures, and it is among the most important atmospheric pollutants. However, this compound has interesting biological activities, since it can control important biological processes in living organisms. With the aim of developing new materials that can be used as selective chemical sensors or as biomedical NO delivery agents we carried out a quantum mechanical study of the interaction of NO with aluminum phthalocyanine (AlPc) at B3LYP/6-31G* level. The calculation results show clearly that the complexation of NO with AlPc depends on the latter's oxidation state. NO is more strongly bonded to AlPc in the reduced state (-33.77 kcal/mol) than in the oxidized state (-4.96 kcal/mol). By applying the Fukui function and analysis of the Frontier molecular orbital, it was possible to explain the situation within which nitric oxide interacts with AlPc. PMID:21342778

Silva, Valter H C; Martins, Marcos P; de Oliveira, Heibbe C B; Camargo, Ademir J

2010-11-03

221

Dimer formation in phthalocyanine-doped sol-gel materials  

NASA Astrophysics Data System (ADS)

A number of different organic molecules have been used as optical probes of the sol-gel process. There is relatively little information, however, as to whether these molecules remain well isolated within the sol-gel structure or if they tend to form dimers or higher aggregates within the network. This issue is particularly important for doped sol-gel optical materials as dimer formation can exert a significant influence on the optical properties of dyes. The present paper uses the optical absorption characteristics of copper phthalocyanine tetrasulfonate (CuPcts) to determine how the state of the dye is affected by the chemical changes during the sol-gel process. The absorption spectra of CuPcts indicate that the dye molecules are dimerized in acid-catalyzed silica xerogels prepared from TMOS. The dimerization is largely controlled by the chemical environment inside the pores. By using appropriate reference solutions, we are able to identify the factors which cause dimerization and the stages of the sol-gel-xerogel transformation when the dimers form. These factors include the quantity of solvent remaining in the pores, the alcohol/water content of the solvent and its acidity. It is shown that by modifying the sol-gel processing conditions and the solvent chemistry within the pores, it is possible to reduce significantly dimer formation in silica xerogels.

Fuqua, Peter D.; Dunn, Bruce S.; Zink, Jeffrey I.

1994-10-01

222

New approaches to photodynamic therapy of tumors with Al phthalocyanine  

NASA Astrophysics Data System (ADS)

The aim of the study was to determine the efficacy of photodynamic therapy (PDT) of tumors of different localization and histology with new photosensitizer aluminum sulfonated phthalocyanine (Photosense, Russia). PDT have been provided in 106 patients with different tumors. The initial dose (2.0 - 2.5 mg/kg) of PHS was significantly reduced till 0.5 - 0.8 mg/kg during clinical trials because of phototoxicity. The results of PDT, side effects and ways of their correction and prevention, as well as possibility to work out less toxic regimes of PDT with photosense, choice of laser and type of irradiation are discussed. Efficacy of PDT depended on tumor size and it's histological type. Using low doses of PHS we've reduced the phototoxicity of sensitizer with the same direct effectiveness of treatment. Undesirable changes in plasma content of antioxidants by means of high pressure liquid chromatography have been found in patients after PHS injection. Influence of short-term and long-term supplementation with beta- carotene and vitamin E on this parameters are discussed.

Vakoulovskaia, Elena G.; Chental, Victor V.; Kuvshinov, Yury P.; Poddubny, Boris K.

1999-12-01

223

Electrochemical and spectroelectrochemical studies of cobalt phthalocyanine polymers  

SciTech Connect

Spectroscopic and electrochemical properties of cobalt phthalocyanine (CoPc) polymers, which are believed to have two- and three-dimensional structures, have been studied and the results are reported. The spectral bands are shifted and a significant band broadening is observed as expected. The cyclic voltammetric results suggest that there are two energetically different Co ions in the three-dimensional polymer. The spectroscopic and electrochemical results indicate that the Co ion on the polymers appears to be in a partially reduced state in solution phases, as evidenced by the presence of the metal-ligand charge-transfer band. When adsorbed onto the carbon surface, this band becomes more prominent even in the formally unreduced state, perhaps due to the coordination of {pi}-electron clouds of carbon into the coaxial axis of the complex, resulting in the partially reduced Co ion. As a result of this partial reduction, the electron transfer from CoPc polymers appears to be enhanced, which becomes the basis for the catalytic activities observed for this class of compounds.

Ortiz, B.; Park, S.M. [Univ. of New Mexico, Albuquerque, NM (United States). Dept. of Chemistry; Doddapaneni, N. [Sandia National Labs., Albuquerque, NM (United States). Battery Research Dept.

1996-06-01

224

Multichromophoric phthalocyanine-(perylenediimide)(8) molecules: a photophysical study.  

PubMed

We describe the synthesis of a series of phthalocyanine (Pc)-perylenediimide (PDI)(8) "octad" molecules, in which eight PDI moieties are attached to a Pc core through alkyl-chain linkers. There is clear spectroscopic evidence that these octads can exist as non-aggregated "monomers" or form aggregates along the Pc cores, depending on the type of Pc and the solvent medium. In the low dielectric constant solvents, into which the octads are soluble, photoexcitation of the PDI units leads to rapid energy transfer to the Pc centre, rather than a charge separation between moieties. In octad monomers, the Pc singlet excited-state decays within tens of ps, whereas the excitons are stabilised in the aggregated form of the molecules, typically with lifetimes in the order of 1-10 ns. By contrast, in an octad design in which pi-pi interactions are suppressed by the steric hindrance of a corona of incompatible glycol tails around the molecule, a more straightforward photophysical interaction of Förster energy transfer between the PDI moieties and Pc core may be inferred. We consider these molecules as prototypical multichromophoric aggregates, giving delocalised states with considerable flexibility of design. PMID:20645341

Albert-Seifried, Sebastian; Finlayson, Chris E; Laquai, Frederic; Friend, Richard H; Swager, Timothy M; Kouwer, Paul H J; Jurícek, Michal; Kitto, Heather J; Valster, Sanne; Nolte, Roeland J M; Rowan, Alan E

2010-09-01

225

Allometric scaling of pegylated liposomal anticancer drugs.  

PubMed

Pegylated liposomal formulations contain lipid conjugated to polyethylene glycol. The disposition of encapsulated drug is dictated by the composition of the liposome, thus altering the pharmacokinetic (PK) profile of the drug. Allometric scaling is based on a power-log relationship between body weight (W) and drug clearance (CL) among mammals and has been used to compare the disposition of nonliposomal drugs across species. The objectives of this study were to use allometric scaling to: (1) compare the disposition of pegylated liposomal drugs across speciesand determine the best scaling model and (2) predict PK parameters of pegylated liposomal drugs in humans. The PK of pegylated liposomal CKD-602 (S-CKD602), doxorubicin (Doxil®), and cisplatin (SPI-077) were compared. PK studies ofS-CKD602, Doxil®, and SPI-077 were performed at the maximum tolerated dose (MTD) in male and female mice, rats, dogs and patients with refractory solid tumors. The allometric equation used to evaluate the relationship between W and CL in each species was CL = a(W)(m) (a = empirical coefficient; m = allometric exponent). Substitution of physiological variables other than body weight, such as factors representative of the mononuclear phagocyte system (MPS) were evaluated. Dedrick Plots and Maximum Life-Span Potential (MLP) were used to determine scaling feasibility. Standard allometry demonstrated a relationship between clearance of S-CKD602, Doxil®, and SPI-077 and body, spleen, liver, and kidney weights, total monocyte count, and spleen and liver blood flow. However, using scaling to predict CL of these agents in humans often resulted in differences >30%. Despite a strong correlation between body weight and MPS-associated variables with CL among preclinical species, the use of the equations did not predict CL. Thus, new methods of allometric scaling and measures of MPS function need to be developed. PMID:21863380

Caron, Whitney P; Clewell, Harvey; Dedrick, Robert; Ramanathan, Ramesh K; Davis, Whitney L; Yu, Ning; Tonda, Margaret; Schellens, Jan H; Beijnen, Jos H; Zamboni, William C

2011-08-24

226

Synthesis, characterization and electrical and CO 2 sensing properties of triazine containing three dendritic phthalocyanine  

Microsoft Academic Search

The metal-free phthalocyanine 1a was synthesised by statistically mixed condensation of 4-nitrophthalonitrile and 4-(2-dimethylaminoethylsulfanyl)phthalonitrile in dry 2-(dimethylamino)ethanol. The same route were applied to prepare metal-containing phthalocyanines using metal salts Zn(OAc)3·2H2O and CoCl2, respectively, in dry DMF. The nitro compounds were reduced to amine with sodium sulfide and quarternized by reaction of MeI. These compounds were then reacted with cyanuric chloride

Mustafa Sülü; Ahmet Alt?ndal; Özer Bekaro?lu

2005-01-01

227

Magnetic, electronic, and vibrational properties of metal and fluorinated metal phthalocyanines  

NASA Astrophysics Data System (ADS)

The magnetic and electronic properties of metal phthalocyanines (MPc) and fluorinated metal phthalocyanines (F16MPc) are studied by means of spin density functional theory (SDFT). Several metals (M) such as Ca, all first d-row transition metals, and Ag are investigated. By considering different open shell transition metals it is possible to tune the electronic properties of MPc, in particular the electronic molecular gap and total magnetic moment. Besides determining the structural and electronic properties of MPc and F16MPc, the vibrational modes of the ScPc-ZnPc series have been studied.

Arillo-Flores, O. I.; Fadlallah, M. M.; Schuster, C.; Eckern, U.; Romero, A. H.

2013-04-01

228

Photoreduction of methylviologen catalyzed by phthalocyanine complexes of yttrium(III) and lanthanoid(III) metals  

SciTech Connect

The preparation of phthalocyanine complexes of yttrium, samarium, gadolinium, ytterbium, and lutetium is reported. The PcLnAcO complex (Pc = phthalocyanine dianion and AcO = acetate anion) was found to act as the sensitizer for the photoreduction of methylviologen chloride (MVCl{sub 2}) in a methanol solution upon irradiation with visible light. On the basis of data from visible spectrophotometric studies and laser flash-photolysis studies, the observation is made that the photoreduction of metalophthalocyanine complexes proceeds via an oxidative process, and a reaction scheme is proposed. 15 refs., 2 figs.

Kasuga, Kuninobu; Takahashi, Seiji; Tsukahara, Keiichi (Shimane Univ., Matsue (Japan)); Ohno, Takeshi (Osaka Univ. (Japan))

1990-01-24

229

Decomposition of propylene carbonate in a lithium/metal phthalocyanine cell  

SciTech Connect

Experimental results from a study of the catalytic effect of metal phthalocyanine (MPc) on the gas evolution reaction in Li batteries are reported. The trials comprised galvanostatic discharge tests with a battery containing a Li anode, an MPc cathode and a reference electrode. A gas evolution curve was generated, and further tests were performed with a cell containing FePc to investigate the gas evolution reaction more quickly. The gas evolved was proportional to the discharge capacity and featured propylene as the chief component. The appearance of propylene was attributed to a reaction between Pc and the discharge product of phthalocyanine. 9 references.

Arakawa, M.; Yamaki, J.; Okada, T.

1984-11-01

230

Internalization of paramagnetic phosphatidylserine-containing liposomes by macrophages  

PubMed Central

Background Inflammation plays an important role in many pathologies, including cardiovascular diseases, neurological conditions and oncology, and is considered an important predictor for disease progression and outcome. In vivo imaging of inflammatory cells will improve diagnosis and provide a read-out for therapy efficacy. Paramagnetic phosphatidylserine (PS)-containing liposomes were developed for magnetic resonance imaging (MRI) and confocal microscopy imaging of macrophages. These nanoparticles also provide a platform to combine imaging with targeted drug delivery. Results Incorporation of PS into liposomes did not affect liposomal size and morphology up to 12 mol% of PS. Liposomes containing 6 mol% of PS showed the highest uptake by murine macrophages, while only minor uptake was observed in endothelial cells. Uptake of liposomes containing 6 mol% of PS was dependent on the presence of Ca2+ and Mg2+. Furthermore, these 6 mol% PS-containing liposomes were mainly internalized into macrophages, whereas liposomes without PS only bound to the macrophage cell membrane. Conclusions Paramagnetic liposomes containing 6 mol% of PS for MR imaging of macrophages have been developed. In vitro these liposomes showed specific internalization by macrophages. Therefore, these liposomes might be suitable for in vivo visualization of macrophage content and for (visualization of) targeted drug delivery to inflammatory cells.

2012-01-01

231

Stimuli-Responsive Liposome Fusion Mediated by Gold Nanoparticles  

PubMed Central

We report a new approach to control the fusion activity of liposomes by adsorbing carboxyl-modified gold nanoparticles to the outer surface of phospholipid liposomes. The bound gold nanoparticles can effectively prevent liposomes from fusing with one another at neutral pH value, while at acidic environments (e.g. pH<5), the gold particle stabilizers will detach from the liposomes, with liposome fusion activity resuming. The binding of carboxyl-modified gold nanoparticles to cationic phospholipid liposomes at neutral pH and detaching at acidic pH values are evaluated and confirmed by dynamic light scattering, electron microscopy, fluorescence and UV-vis absorption experiments. The relative fusion efficiency of gold nanoparticle-stabilized cationic liposomes with anionic liposomes is ~25% at pH=7 in contrast to ~80% at pH=4. Since liposomes have been extensively used as drug nanocarriers and the infectious lesions on human skin are typically acidic with a pH<5, these acid-responsive liposomes with tunable fusion ability hold great promise for dermal drug delivery to treat a variety of skin diseases such as acne vulgaris and staph infections.

Pornpattananangkul, Dissaya; Olson, Sage; Aryal, Santosh; Sartor, Marta; Huang, Chun-Ming; Vecchio, Kenneth; Zhang, Liangfang

2010-01-01

232

Iron oxide-loaded liposomes for MR imaging.  

PubMed

In this study a liposome cell labeling system was developed for non-target-specific labeling of glioma cells with superparamagnetic iron oxide nanoparticles for magnetic resonance imaging (MRI). A high non-target-specific uptake is ideal for in vitro labeling of cells and subsequently for cell tracking and visualization of phagocytic cells in vivo. The preparation of iron oxide-loaded liposomes was optimized and the biological properties of the liposomes were investigated. Cytotoxicity and cell viability were examined and showed limited cytotoxic effects. Non-target-specific labeling of glioma cells in vitro for subsequent specific labeling of molecules for MR imaging was tested by T2*-weighted MRI at 3T. The glioma cells showed a strong initial uptake of the iron oxide liposomes and the uptake was not saturable within 24 h exposure. The uptake of liposomes was superior to non-coated magnetite nanoparticles. Using PEG-ylated liposomes, the non-specific uptake could be decreased fundamentally (86% lower) in comparison to conventional liposomes. Furthermore, the ability of liposomes as contrast agents for MR imaging was investigated. Cells labeled with iron oxide nanoparticles by treatment with liposomes showed a negative contrast in MRI and consequently successful cellular labeling. Thus, iron oxide-loaded liposomes are well suited for non-target-specific cell labeling for MR imaging. PMID:18508493

Meincke, Manuela; Schlorf, Thomas; Kossel, Elke; Jansen, Olav; Glueer, Claus-Christian; Mentlein, Rolf

2008-05-01

233

Stimuli-responsive liposome fusion mediated by gold nanoparticles.  

PubMed

We report a new approach to controlling the fusion activity of liposomes by adsorbing carboxyl-modified gold nanoparticles to the outer surface of phospholipid liposomes. The bound gold nanoparticles can effectively prevent liposomes from fusing with one another at neutral pH value, while at acidic environments (e.g., pH < 5), the gold particle stabilizers will detach from the liposomes, with liposome fusion activity resuming. The binding of carboxyl-modified gold nanoparticles to cationic phospholipid liposomes at neutral pH and detaching at acidic pH values are evaluated and confirmed by dynamic light scattering, electron microscopy, fluorescence and UV-vis absorption experiments. The relative fusion efficiency of gold-nanoparticle-stabilized cationic liposomes with anionic liposomes is approximately 25% at pH = 7 in contrast to approximately 80% at pH = 4. Since liposomes have been extensively used as drug nanocarriers and the infectious lesions on human skin are typically acidic with a pH < 5, these acid-responsive liposomes with tunable fusion ability hold great promise for dermal drug delivery to treat a variety of skin diseases such as acne vulgaris and staph infections. PMID:20235571

Pornpattananangkul, Dissaya; Olson, Sage; Aryal, Santosh; Sartor, Marta; Huang, Chun-Ming; Vecchio, Kenneth; Zhang, Liangfang

2010-04-27

234

Bubble liposomes and ultrasound enhance the antitumor effects of AG73 liposomes encapsulating antitumor agents.  

PubMed

Encapsulating anticancer drugs in liposomes improves their therapeutic window by enhancing antitumor efficacy and reducing side effects. To devise more effective liposomal formulations for antitumor therapy, many research groups have tried to develop tumor-targeting liposomes with enhanced drug release. Previously, we developed doxorubicin (Dox)-encapsulated AG73 peptide-modified liposomes (AG73-Dox), which targeted cancer and endothelial cells, and ultrasound (US) imaging gas-entrapping liposomes, called "Bubble liposomes" (BLs). In this study, to enhance the antitumor effect of AG73-Dox, we combined AG73-Dox with BLs and US. First, to determine whether the addition of BLs and application of US could enhance the cytotoxicity of AG73-Dox, we evaluated the cytotoxicity of the combination of AG73-Dox with BLs and US. BLs and US enhanced cytotoxicity of AG73-Dox more than they enhanced nontargeted Dox-encapsulated liposomes. Next, we examined the intracellular behavior of Dox after treatment with BLs and US. The combination of AG73-Dox with BLs and US did not enhance cellular uptake of Dox, but it did promote drug release in the cytoplasm. To further elucidate the release of Dox in the cytoplasm, we blocked cellular uptake via endosomes at a low temperature. As a result, BLs and US did not have an enhanced drug-release effect until AG73-Dox was taken up into cells. Thus, the combination of AG73-Dox with BLs and US may be useful for cancer therapy as a dual-function drug delivery system with targeted and controlled release. PMID:23210449

Hamano, Nobuhito; Negishi, Yoichi; Omata, Daiki; Takahashi, Yoko; Manandhar, Maya; Suzuki, Ryo; Maruyama, Kazuo; Nomizu, Motoyoshi; Aramaki, Yukihiko

2013-01-02

235

Effect of Liposome Characteristics and Dose on the Pharmacokinetics of Liposomes Coated with Poly(amino acid)s  

PubMed Central

Long-circulating liposomes, such as PEG-liposomes, are frequently studied for drug delivery and diagnostic purposes. In our group, poly(amino acid) (PAA)-based coatings for long-circulating liposomes have been developed. These coatings provide liposomes with similar circulation times as compared to PEG-liposomes, but have the advantage of being enzymatically degradable. For PEG-liposomes it has been reported that circulation times are relatively independent of their physicochemical characteristics. In this study, the influence of factors such as PAA grafting density, cholesterol inclusion, surface charge, particle size, and lipid dose on the circulation kinetics of PAA-liposomes was evaluated after intravenous administration in rats. Prolonged circulation kinetics of PAA-liposomes can be maintained upon variation of liposome characteristics and the lipid dose given. However, the use of relatively high amounts of strongly charge-inducing lipids and a too large mean size is to be avoided. In conclusion, PAA-liposomes represent a versatile drug carrier system for a wide variety of applications.

Romberg, Birgit; Oussoren, Christien; Snel, Cor J.; Hennink, Wim E.

2007-01-01

236

A method to measure critical detergent parameters. Preparation of liposomes.  

PubMed

A simple physical method to determine the monomer concentration of detergents below as well as above the critical micelle concentration based on the bubble-pressure measurement is described. Aggregated surfactant molecules (micelles) and phospholipid vesicles if present in the sample will not disturb the measurements. Three applications of the method relevant to the preparation of liposomes are shown: (i) measurements of critical micelle concentrations, (ii) evaluation of the affinity constant of the interaction of detergents with liposomal membranes, and (iii) monitoring of residual detergent in liposome preparations during dialysis or after gel chromatography of mixed micelle-derived liposomes. It was found that the efficiency of detergents to produce liposomes during their removal depends on their critical micelle concentrations as well as on their affinity to liposomal membranes. PMID:6638509

Lasch, J; Berdichevsky, V R; Torchilin, V P; Koelsch, R; Kretschmer, K

1983-09-01

237

[Liposomal formulations of protein proteinase inhibitors: preparation and specific activity].  

PubMed

Here we investigated encapsulation of water-soluble proteins into multilayer liposomes of soybean zwitterionic phospholipid mixtures (phosphatidylcholine (PC) and phosphatidylethanolamine (PE)). The influence of the PC/PE w/w ratio on the incorporation efficiency of the Bowman-Birk soybean proteinase inhibitor (BBI) and aprotinin (BPTI) into liposomes was studied. Protein encapsulation did not affect liposome sizes. Confocal laser scanning microscopy demonstrated that proteins were located in the central part of the spherical particle and between the bilayers. The biological activity (antitrypsin and antichymotrypsin) assay of the protein entrapped in liposomes showed its active sites were spatially shielded. The effect of an ionic detergent on the activity of the encapsulated BBI and BPTI confirmed this hypothesis and suggested that this shielding is reversible. The liposomes stability in three various media-artificial gastric juice and intestinal fluids was also examined. The liposomes prepared seem to be promising formulations for BBI and BPTI delivery. PMID:19105398

Balkina, A S; Selishcheva, A A; Larionova, N I

238

Photo-induced electron transfer between dendritic zinc(II) phthalocyanine bearing carboxylic terminal groups and methyl viologen  

NASA Astrophysics Data System (ADS)

The intermolecular electron transfer between carboxylic dendritic zinc(II) phthalocyanine bearing carboxylic terminal groups(G1-ZnPc(COOH)8) and methyl viologens (MV2+) was studied by steady-state fluorescence and UV/Vis spectroscopy. The effect of different concentrations of MV2+ on intermolecular electron transfer was investigated. The results show that the fluorescence emission of this dendritic phthalocyanine could be greatly quenched with an increasing amount of MV2+ upon excitation at 610 nm. Our study suggests that this novel dendritic phthalocyanine is an effective new electron donor and transmission complex and could be used as a potential biosensor conjugated with suitable fluorescence quencher.

Wang, Yuhua; Chen, Jiangxu; Huang, Lishan; Xie, Shusen; Yang, Hongqin; Peng, Yiru

2012-12-01

239

Pump-probe experiments with sub-100 femtosecond pulses for characterizing the excited state dynamics of phthalocyanine thin films  

NASA Astrophysics Data System (ADS)

We present our results on the characterization of ultrafast excited state dynamics of two phthalocyanines in thin film form studied using femtosecond pump-probe technique. One was a symmetric Zinc phthalocyanine (SPc) while the other was an unsymmetrical Zinc phthalocyanine (USPc). The femtosecond (fs) pulses at 800 nm were characterized using a single shot autocorrelator. The pump probe measurements were carried out with 590/610 nm pulses emanating from an optical parametric amplifier. SPc demonstrated an excited lifetime of ~30 ps while the ASPc exhibited ~60 ps lifetime. The potential applications of these molecules are discussed briefly.

Rao, S. Venugopal; Swain, Debasis; Tewari, Surya P.

2010-02-01

240

Development of Spray Dried Liposomal Dry Powder Inhaler of Dapsone  

Microsoft Academic Search

This investigation was undertaken to evaluate practical feasibility of site specific pulmonary delivery of liposomal encapsulated\\u000a Dapsone (DS) dry powder inhaler for prolonged drug retention in lungs as an effective alternative in prevention of Pneumocystis carinii pneumonia (PCP) associated with immunocompromised patients. DS encapsulated liposomes were prepared by thin film evaporation\\u000a technique and resultant liposomal dispersion was passed through high

Mahavir Chougule; Bijay Padhi; Ambikanandan Misra

2008-01-01

241

Endocytosis and intracellular processing accompanying transfection mediated by cationic liposomes  

Microsoft Academic Search

Cationic liposomes mediate efficient transfection of mammalian cells, but the manner in which cells internalize and process cationic liposome-DNA complexes has not been well characterized. We exposed several cell types, including human and murine erythroleukemia cells, African green monkey kidney cells (CV-1), isolated rat alveolar type II cells and alveolar macrophages to DNA-cationic liposome complexes containing N-(1-2,3-dioleyloxypropyl)-N,N,N-triethylammonium (DOTMA) and Dioleylphosphatidylethanolamine

Daniel S Friend; Demetrios Papahadjopoulos; Robert J Debs

1996-01-01

242

Prevention of Chronic Doxorubicin Cardiotoxicity in Beagles by Liposomal Encapsulation  

Microsoft Academic Search

Antitumor drugs such as doxorubicin have been encapsulated into liposomes as a means of enhancing activity and reducing toxicity. The present study was initiated to determine whether chronically administered liposome-encapsulated doxorubicin would be less toxic than the free drug. Doxorubicin was prepared in positively charged cardiolipin liposomes, and 1.75 mg\\/kg was given i.v. to each of five beagles. A second

E. H. Herman; A. Rahman; V. J. Ferrans; J. A. Vick; P. S. Schein

243

Analysis of liposomal membrane composition using Raman tweezers.  

PubMed

We have developed a methodology for the analysis of liposomal membranes and their contents using near-IR Raman spectroscopy on liposomes held in an optical trap. We were able to detect a variety of membrane components including lipids, cholesterol, and small molecule solutes such as ethanol, DMSO and hexafluoroisopropanol. The methodology is able to distinguish between solutes that equilibrate across the liposomal membrane from those that partition selectively into the lipid bilayer. PMID:15116214

Sanderson, John M; Ward, Andrew D

2004-04-06

244

Targeting Anticancer Drugs to Tumor Vasculature Using Cationic Liposomes  

Microsoft Academic Search

Liposomal drug delivery systems improve the therapeutic index of chemotherapeutic agents, and the use of cationic liposomes\\u000a to deliver anticancer drugs to solid tumors has recently been recognized as a promising therapeutic strategy to improve the\\u000a effectiveness of conventional chemotherapeutics. This review summarizes the selective targeting of cationic liposomes to tumor\\u000a vasculature, the merits of incorporating the polymer polyethylene-glycol (PEG),

Amr S. Abu Lila; Tatsuhiro Ishida; Hiroshi Kiwada

2010-01-01

245

Liposomal formulations of poorly soluble camptothecin: drug retention and biodistribution.  

PubMed

Camptothecin (CPT) represents a potent anticancer drug. However, its therapeutic use is impaired by both drug solubility, hydrolysis, and protein interactions in vivo. Use of liposomes as a drug-formulation approach could overcome some of these challenges. The aim of this study was to perform a mechanistic study of the incorporation and retention of the lipophilic parent CPT compound in different liposome formulations using radiolabeled CPT and thus to be able to identify promising CPT delivery systems. In this context, we also wanted to establish an appropriate mouse tumor model, in vivo scintigraphic imaging, and biodistribution methodology for testing the most promising formulation. CPT retention in various liposome formulations after incubation in buffer and serum was determined. The HT-29 mouse tumor model, (111)In-labeled liposomes, as well as (3)H-labeled CPT were used to investigate the biodistribution of liposomes and drug. The ability of different liposome formulations to retain CPT in buffer was influenced by lipid concentration and drug/lipid ratio, rather than lipid composition. The tested formulations were cleared from the blood in the following order: CPT solution > CPT liposomes > (111)In-labeled liposomes, and liposomes mainly accumulated in the liver. Lipid composition did not influence CPT retention to the same extent as earlier observed from incorporation studies. The set-up for the biodistribution study works well and is suited for future in vivo studies on CPT liposomes. The biodistribution study showed that liposomes circulated longer than free drug, but premature release of drug from liposomes occurred. Further studies to develop formulations with higher retention potential and prolonged circulation are desired. PMID:23210622

Flaten, Gøril Eide; Chang, Ting-Tung; Phillips, William T; Brandl, Martin; Bao, Ande; Goins, Beth

2012-12-05

246

Comparative photodynamic therapy study using two phthalocyanine derivatives  

PubMed Central

In the present study, a comparative photodynamic therapy (PDT) study was performed using the phthalocyanine derivatives, ZnPc(OCH3)4 and ZnPc(CF3)4, in a mouse tumor model, under identical experimental procedures. We studied the ablation of tumors induced by PDT. The end-point was to compare the photodynamic efficacy of ZnPc(OCH3)4 and ZnPc(CF3)4. ZnPc(OCH3)4 and ZnPc(CF3)4 were administered intraperitoneally at a dose of 0.2 mg/kg body weight. The injections of drugs were carried out in Balb/c mice bearing subcutaneously inoculated LM2 mouse mammary adenocarcinoma. Histological examination and serum biochemical parameters were used to evaluate hepatic and renal toxicity and function. Phototherapeutic studies were achieved employing a light intensity of 210 J/cm2. After PDT, tumoral regression analyses were carried out, and the degree of tumor cell death was measured utilizing the vital stain Evan’s blue. In this pilot study, we revealed that the cytotoxic effect of ZnPc(OCH3)4 after PDT led to a higher success rate compared to ZnPc(CF3)4-PDT when both were intraperitoneally injectioned. Both phthalocynanine derivatives were able to induce ablation in the tumors. In summary, these results demonstrate the feasibility of ZnPc(OCH3)4- or ZnPc(CF3)4-PDT and its potential as a treatment for small tumors.

YSLAS, EDITH INES; MILLA, LAURA NATALIA; ROMANINI, SILVIA; DURANTINI, EDGARDO NESTOR; BERTUZZI, MABEL; RIVAROLA, VIVIANA ALICIA

2010-01-01

247

Nonlinear optical response of cofacial phthalocyanine dimers and trimers  

SciTech Connect

The effects of intermacrocycle interactions on the second hyperpolarizabilities {l_angle}{gamma}({minus}{omega};{omega},{minus}{omega},{omega}){r_angle} of cofacial phthalocyanine dimers and trimers are studied. A theoretical analysis is presented based on the Frenkel exciton model for a chain of three level molecules. Using a simplified analysis in the static and near-resonant regimes we identify two mechanisms which lead to enhancements in the dimer or trimer value of {l_angle}{gamma}({minus}{omega};{omega},{minus}{omega},{omega}){r_angle} over that of the monomer. The first mechanism is a disruption of the balance between type I and type II terms in the sum over states expression for the second hyperpolarizability tensor {gamma}{sub kjih}({minus}{omega};{omega},{minus}{omega},{omega}), caused by weak intermacrocycle interactions. The second is a near-resonance enhancement of the type II terms due to an intermacrocycle interaction induced shift in the monomer derived two-photon allowed states towards twice the laser photon energy. This analysis is in good agreement with recent degenerate four wave mixing experiments [SPIE Proc. {bold 2527}, 61 (1995)] which showed a strong enhancement of {l_angle}{gamma}({minus}{omega};{omega},{minus}{omega},{omega}){r_angle} for SiPcO oligomers as a function of the number of macrocycles. Our calculations suggest that the first mechanism is responsible for the 25-fold monomer to dimer enhancement measured in this system, and that the additional 4-fold enhancement found in going from the dimer to the trimer is primarily the result of the second mechanism. {copyright} {ital 1997 American Institute of Physics.}

Manas, E.S.; Spano, F.C. [Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122 (United States); Chen, L.X. [Chemistry Division, Argonne National Laboratory, 9700 S. Cass Avenue, Argonne, Illinois 60439 (United States)

1997-07-01

248

Tetrasulphonated aluminum phthalocyanine as a pH-sensitive probe  

NASA Astrophysics Data System (ADS)

PH is a factor relevant for the molecular state of the sensitizer used in PDT and so may influence its photochemical activity and its interaction with cells and tissues. Thus the measurements of microenvironmental pH of the sensitizing molecule, its dynamics during irradiation with light and subsequent development of cell damage are interesting from the point of view of the PDT molecular and cellular mechanisms. Two ways of performing such measurements are suggested: the first one is to use conventional fluorescence or transmission pH-probes, and second using the sensitizer itself as such a probe. We show the complications arising in the first approach due to the interaction between the probing and sensitizing molecules on the example of measurements of the microenvironment pH of tetrasulphonated aluminum phthalocyanine (AlPcS4) in cultured cells with the use of neutral red. These complications are expected to be common also for the other conventional pH-probes. We studied concentrational and pH dependencies of the fluorescence emission, fluorescence excitation and absorbance spectra, and fluorescence lifetimes of AlPcS4 in aqueous solutions (10-6 M - 10-4 M) by means of stationary and laser picosecond fluorescence spectroscopies. With the use of numerical deconvolution of complex spectral curves (Alentsev - Fok algorithm) three individual components were found in AlPcS4 pH-dependent fluorescence spectra. Based on the spectral data we suggest a ratioing technique for the local pH measurements with the use of AlPcS4 as a fluorescence pH- sensitive probe. Microenvironmental pH of AlPcS4 molecules in cultured cells were estimated by means of the suggested technique.

Chernyaeva, Elena B.; Poroshina, Marina Y.; Zhorina, L. V.; Agronskaya, A. V.; Chikishev, A. Y.; Schinov, V. A.; Ardgantsev, S. Y.; Galpern, Maria G.

1995-01-01

249

Backward propagation of light pulse in phthalocyanin gallium PMMA at room temperature  

Microsoft Academic Search

Light speed control had been an interesting issue in recent years. In this work, the authors experimentally observed the backward propagation of light pulse in Phthalocyanin Gallium polymethyl methacrylate (PMMA) at room temperature, firstly. Taking use of the modulation technique, we got the time advancement of 260 mus when the sample length was 2 mm long and the modulation frequency

Hao Wang; Chunguang Zhang

2010-01-01

250

On the mechanism of hydrogen peroxide decomposition over monomeric and polymeric cobalt phthalocyanines  

Microsoft Academic Search

The decomposition of hydrogen peroxide in alkaline solutions on the surface of monomeric and polymeric cobalt phthalocyanines has been studied by means of volumetric, electrochemical and isotopic measurements. It has been shown that at a steady potential peroxide decomposition proceeds by the catalase mechanism and is a secondorder reaction. According to the results of18O tracer experiments, the evolving oxygen has

M. R. Tarasevich; G. I. Zakharkin

1977-01-01

251

Spectroelectrochemical characterization and controlled potential chronocoulometric demetallation of tetra- and octa-substituted lead phthalocyanines  

Microsoft Academic Search

The solution redox properties and spectroelectrochemical investigation of the novel lead phthalocyanines carrying chloro alkylthio and alkylmalonyl at periphery were studied using various electrochemical techniques in DCM on a platinum electrode. Cyclic voltammetry and differential pulse voltammetry studies show that all of the complexes give up to five ligand-based diffusion controlled one-electron reversible redox couples. Assignments of the redox couples

At?f Koca; Hatice A. Dinçer; Hatice Çerlek; Ahmet Gül; Makbule B. Koçak

2006-01-01

252

Reverse optical changing and rewrite recording properties of Langmuir-Blodgett films of phthalocyanine copper  

NASA Astrophysics Data System (ADS)

Langmuir-Blodgett (LB) films of tetra-nonyl phthalocyanine copper (TNPcCu) were prepared and annealed at different temperatures. Their optical spectra and optical constants were measured, the structural changes of the films were studied by x-ray diffraction. Optical recording properties were measured at a static optical recording tester.

Gan, Fuxi; Luo, Tao

1994-01-01

253

A Mechanistic Study of O2 Reduction on Water Soluble Phthalocyanines Adsorbed on Graphite Electrodes.  

National Technical Information Service (NTIS)

Co and Fe tetrasulfonate phthalocyanines (M-TSP), adsorbed at monolayer levels on graphite surfaces, have been found to have a pronounced catalytic effect on the O2 reduction process in both acid and alkaline solutions. The kinetics have been examined wit...

J. Zagal P. Bindra E. Yeager

1979-01-01

254

Molecular Interactions Between Alcohols and Metal Phthalocyanine Thin Films for Optical Gas Sensor Applications  

NASA Astrophysics Data System (ADS)

Optically active organic gas sensors represent a promising molecular sensing device with low power consumption. We report experimental and computational investigations into the molecular interactions of metal phthalocyanine thin films with alcohol vapor. In the gas-sensing regime, the interactions of zinc phthalocyanine and alcohol molecules were studied by the Density Functional Theory (DFT) calculations, in comparison to the x-ray absorption spectroscopy. The DFT results reveal a reversible charge interaction mechanism between the zinc atom and the oxygen atom in the alcohol OH group, which corresponds to a shift in the x-ray absorption edge of the zinc atom. In the irreversible interaction regime, the effect of saturated alcohol vapor on spin-coated zinc phthalocyanine films was studied by the phase contrast microscopy, the optical absorption spectroscopy, and the transmission electron microscopy. Annealing the spin-coated films in saturated methanol vapor was found to induce an irreversible structural transformation from an amorphous to a crystalline phase, similar to the effect of a thermal annealing process. These crystallization processes of the zinc phthalocyanine films were also found to enhance their stability and alcohol sensing performance.

Uttiya, Sureeporn; Kladsomboon, Sumana; Chamlek, Onanong; Suwannet, Wiriya; Osotchan, Tanakorn; Kerdcharoen, Teerakiat; Brinkmann, Martin; Pratontep, Sirapat

255

Photodynamic pathogen inactivation in red cell concentrates with the silicon phthalocyanine Pc 4  

Microsoft Academic Search

The silicon phthalocyanine Pc 4, a photosensitizer activated with red light, has been studied for pathogen inactivation in red blood cell concentrates (RBCC). Pc 4 targets the envelope of pathogenic viruses such as HIV. To protect RBC during the process two main approaches are used: 1) Inclusion of quenches of reactive oxygen species produced during treatment. Tocopherol succinate was found

Ehud Ben-Hur; Wai-Shun Chan; Zachary Yim; Maria M. Zuk; Vinay Dayal; Nathan Roth; Eli Heldman; A. Lazlo; C. R. Valeri; Bernard Horowitz

2000-01-01

256

Direct measurements of nonlinear absorption and refraction in solutions of phthalocyanines  

Microsoft Academic Search

We report direct measurements of the excited singlet state absorption cross section and the associated nonlinear refractive cross section using picosecond pulses at 532 nm in solutions of phthalocyanine and naphthalocyanine dyes. By monitoring the transmittance and far field spatial beam distortion for different pulsewidths in the picosecond regime, we determine that both the nonlinear absorption and refraction are fluence

T. H. Wei; D. J. Hagan; M. J. Sence; E. W. Stryland; J. W. Perry; D. R. Coulter

1992-01-01

257

Metabolism of the phthalocyanine textile dye remazol turquoise blue by Phanerochaete chrysosporium  

Microsoft Academic Search

The ability of a strain of Phanerochaete chrysosporium to decolourise the commercially important copper-phthalocyanine dye Remazol turquoise blue was investigated. The fungus was found to completely decolourise the dye at a concentration of 200 mg l?1 within 7 days. High performance liquid chromatography (HPLC) and polarographic analysis of culture supernatants indicated that degradation of the dye structure was occurring with

A Conneely; W. F Smyth; G McMullan

1999-01-01

258

A sandwich-type triple-decker lanthanide complex with mixed phthalocyanine and Schiff base ligands.  

PubMed

A new triple-decker dinuclear sandwich-type dysprosium complex based on both the phthalocyanine ligand and the tetradentate Schiff base ligand was synthesized, which is of interest for synthetic chemistry and also shows single-molecule magnetic behaviour. PMID:23818021

Gao, Feng; Li, Yu-Yang; Liu, Cai-Ming; Li, Yi-Zhi; Zuo, Jing-Lin

2013-08-21

259

Intramolecular reorganization energy in zinc phthalocyanine and its fluorinated derivatives: a joint experimental and theoretical study.  

PubMed

We report a high-resolution gas-phase UPS spectrum of zinc phthalocyanine (ZnPc) together with a detailed analysis of the vibronic structure of the first ionization band, showing that presents the lowest value of the intramolecular reorganization energy experimentally reported for a molecular organic semiconductor. PMID:23722445

da Silva Filho, Demetrio A; Coropceanu, Veaceslav; Gruhn, Nadine E; de Oliveira Neto, Pedro Henrique; Brédas, Jean-Luc

2013-07-11

260

Stability of benzotriazolyl-substituted phthalocyanines with respect to thermal oxidative decomposition  

NASA Astrophysics Data System (ADS)

The thermal oxidative decomposition of benzotriazolyl-substituted phthalocyanines and their copper complexes is investigated by means of thermogravimetric, elemental, and spectroscopic analysis. It is shown that the nature of peripheral substituents exerts the greatest effect on the thermal stability of the compounds.

Znoiko, S. A.; Maizlish, V. E.; Shaposhnikov, G. P.; Lebedeva, N. Sh.; Mal'kova, E. A.

2013-03-01

261

Molecular materials by self-assembly of porphyrins, phthalocyanines, and perylenes  

Microsoft Academic Search

Porphyrins, phthalocyanines, and perylenes are compounds with great potential for serving as components of molecular materials that possess unique electronic, magnetic and photophysical properties. In general, a highly specific commu- nication between a large number of these chromophores is required in order to express their function to a maximal level, and for this reason it is of importance to construct

Johannes A. A. W. Elemans; Richard van Hameren; Roeland J. M. Nolte; Alan E. Rowan

2006-01-01

262

Copper phthalocyanine as an efficient dopant in development of solar cells  

SciTech Connect

Organic semiconductors having conjugate bonds, such as phthalocyanines, are well known photoconductors. Phthalocyanines absorb light on either side of blue-green region in the visible spectrum. And polyaniline which has conjugate bonds is photosensitive. When polyaniline thin films are prepared with copper phthalocyanine powder the magnitude of absorption of the films not only increases but also broadens, indicating a wide absorption region between 1.7 and 2.3 eV and above 3.0 eV of the visible spectrum. Thus copper phthalocyanine in preparation of thin films is shown to smooth the broadening effect in absorption of solar cells. Attempts are underway to increase the absorption on either end of the visible spectrum, viz., infrared as well as ultraviolet regions, using suitable dopants. This would ensure the overall efficiency of solar cells made of organic photoconductive materials to absorb solar energy from infrared to ultraviolet regions of the optical spectrum, thereby making them more efficient solar energy converters.

Inigo, A.R.; Xavier, F.P. [Loyola Coll., Madras (India); Goldsmith, G.J. [Boston Coll., Chestnut Hill, MA (United States). Physics Dept.

1997-05-01

263

Nanoparticles improve biological functions of phthalocyanine photosensitizers used for photodynamic therapy.  

PubMed

Photodynamic therapy (PDT) is a new technology using photodynamic effect for disease diagnosis and treatment. It is a two-step technique involving the uptake of a photosensitizer by cancer tissue followed by light irradiation that excites the photosensitizer to produce highly reactive oxygen species, the latter execute apoptosis of cancerous cells. As a second-generation of photosensitizers, phthalocyanine demonstrates higher absorption in the 650-800 nm range and short tissue accumulation compared to their first generation. However, many potent phthalocyanine photosensitizers are hydrophobic and poorly water-soluble, which limit their therapeutic applications. As a result, advanced delivery systems and different strategies are called for to improve the effectiveness of PDT. Facts have proved that using nanoparticles as carries of photosensitizers is a very promising route. Nanoparticles have the potentials to increase photosensitizers' aqueous solubility, bioavailability and stability, and deliver photosensitizers to the target tissues. This article reviewed the commonly-used nanoparticles, including colloid gold, quantum dots, paramagnetic nanoparticles, silica-based materials, polymer-based nanoparticles, as potential delivery systems for phthalocyanine photosensitizers, and summarized the improved biological functions of phthalocyanine photosensitizers in PDT. PMID:22380016

Jia, Xiao; Jia, Lee

2012-10-01

264

Incorporation of phthalocyanines by cationic and anionic clays via ion exchange and direct synthesis  

SciTech Connect

Phthalocyanines (Pc) and metallophthalocyanines were incorporated into the galleries of anionic and cationic clays via ion exchange and in situ crystallization of the synthetic clay layers. Intercalation compounds between the layered magnesium silicate clay hectorite and cationic phthalocyanines were directly prepared by refluxing for 2 days aqueous solutions of silica sol, magnesium hydroxide, lithium flouride, and either alcian blue dyes (Cu(II)Pc) or 15-crown-5 tetra-substituted phthalocyanine (15C5Pc). The CuPc dyes are tetrapositively charged through peripheral quaternary ammonium groups, whereas the 15C5Pc is electrically neutral. Anionic clays prepared by hydrolysis of mixed solutions of aluminum nitrate, magnesium nitrate, and copper(II) phthalocyaninetetrasulfonic acid, tetrasodium salt (CuPcTs) in sodium hydroxide resulted in crystallization of an intercalation compound between a layered double hydroxide (LDH) and this anionic Pc. The material prepared by ion exchange of CuPcTs into a wet, freshly prepared LDH was superior in crystallinity. The phthalocyanines are oriented parallel to cationic hectorite clay layers (gallery heights 4.5-6.5[angstrom]) and perpendicular to anionic layered double hydroxide clay layers (gallery height 18,2[angstrom]) in correlation with their hosts' respective layer charge densities. 32 refs., 4 figs., 2 tabs.

Carrado, K.A.; Botto, R.E.; Winans, R.E. (Argonne National Laboratory, IL (United States)); Forman, J.E. (CalTech, Pasadena, CA (United States))

1993-04-01

265

Transient photoresponse measurements in x-phase of metal-free phthalocyanine photovoltaic cells  

Microsoft Academic Search

Transient response of In\\/x phase of metal-free phthalocyanine Schottky barrier photovoltaic cells as a function of the applied reverse bias has been investigated under pulse and step illumination conditions. In both cases the dependence of the photoresponse on the applied bias showed the change in shape when the light wavelength was changed. This can be interpreted in the framework of

Zoran D. Popovic; Rafik O. Loutfy

1981-01-01

266

Panchromatic light harvesting in single wall carbon nanotube hybrids-immobilization of porphyrin-phthalocyanine conjugates.  

PubMed

We report on immobilizing H(2)/Zn-porphyrin-Zn-phthalocyanine conjugates onto single wall carbon nanotubes and by using the excellent stability of the resulting suspensions we were able to demonstrate for the first time the sequence of energy transfer-electron transfer in SWNT donor-acceptor conjugates. PMID:21301742

Bartelmess, Juergen; Soares, Ana R M; Martínez-Díaz, M Victoria; Neves, Maria G P M S; Tomé, Augusto C; Cavaleiro, José A S; Torres, Tomás; Guldi, Dirk M

2011-02-08

267

[Isolation and low-temperature preservation of liposomes containing rifampicin].  

PubMed

The optimal conditions for preparations of rifampicin-containing liposomes were determined with the methods of mechanical shaking, gas dispersion and and reversible phases. It was found that the percentage of rifampicin incorporation into liposomes depended on the molar ratio of the antibiotic to the lipid (the optimal ratio was 1 : 10), the size and structure of liposomes, the amount of cholesterol added and the lipid membrane charge. Incorporation of rifampicin amounted to 16.1 +/- 2.4, 39.2 +/- 3.2 and 60.5 +/- 2.9 per cent with respect to neutral lecithin multilamellar liposes, liposomes prepared with the gas dispersion method and liposomes prepared with the method of reversible phases, respectively. Cholesterol in a molar ratio to lecithin equal to 2 : 5 or higher and dicetyl phosphate imparting the negative charge to the membrane had an inhibitory effect on the drug uptake by liposomes, while stearyl amine having the positive charge had a stimulating effect. The effect of the cryoprotectors glucose, polyvinylpyrrolidone, poly-ethylene glycole-400 and glycerol on low-temperature preservation and storage of rifampicin-containing liposomes was studied. It was shown that 10--15 per cent solutions of sucrose and glucose had the highest cryoprotective effect, when the two-stage method of freezing was used. It provided almost 84 per cent preservation of liposomal rifampicin. Electron microscopy showed that after defrosting liposomes no significant changes in the size and structure of lipid membranes were observed. PMID:6638970

Tsyganenko, A Ia; Vasil'chenko, V N; Leont'ev, V S; Vasil'chenko, N S; Dedukh, N V

1983-08-01

268

Liposomal glyco-microarray for studying glycolipid-protein interactions.  

PubMed

A microarray enables high-throughput interaction screening of numerous biomolecules; however, fabrication of a microarray composed of cellular membrane components has proven difficult. We report fabrication of a liposomal glyco-microarray by using an azide-reactive liposome that carries synthetic and natural glycolipids via chemically selective and biocompatible liposome immobilization chemistry. Briefly, liposomes carrying anchor lipid dipalmitoylphosphatidylethanolamine (DPPE)-PEG(2000)-triphenylphosphine and ganglioside (GM1 or GM3) were prepared first and were then printed onto an azide-modified glass slide so as to afford a liposomal glyco-microarray via Staudinger ligation. Fluorescent dye release kinetics and fluorescence imaging confirmed successful liposome immobilization and specific protein binding to the intact arrayed glycoliposomes. The liposomal glyco-microarray with different gangliosides showed their specific lectin and toxin binding with different binding affinity. The azide-reactive liposome provides a facile strategy for fabrication of either a natural or a synthetic glycolipid-based membrane-mimetic glycoarray. This liposomal glyco-microarray is simple and broadly applicable and thus will find important biomedical applications, such as studying glycolipid-protein interactions and toxin screening applications. PMID:22627703

Ma, Yong; Sobkiv, Irena; Gruzdys, Valentinas; Zhang, Hailong; Sun, Xue-Long

2012-05-25

269

Release of liposomal markers by Cerebratulus toxin A-III.  

PubMed

Marker release from liposomes induced by the cytolytic protein Cerebratulus lacteus toxin A-III was studied. No phospholipid specificity was apparent, but the sensitivity of liposomes to A-III varied with the membrane fluidity. With dioleylphosphatidylcholine liposomes, complete release occurred at 10-20 micrograms toxin per ml, depending on marker size. Kinetic experiments showed that release was rapid and exhibited no lag phase. The diameter of the A-III produced membrane lesion must exceed 90 A, as tetrameric Concanavalin A is quantitatively released from A-III treated liposomes. PMID:6375665

Blumenthal, K M

1984-05-31

270

The preparation and characterization of gas bubble containing liposomes.  

PubMed

Liposomes and lipid nano-particles containing gas bubbles have great potentials to be used as ultrasound contrast agents or as drug and gene delivery vehicles. We developed a method to enable in situ CO2gas bubbles formation inside liposomes. The resulted bubbles containing liposomes were shown to be able to effectively echo ultrasound. Their acoustic properties were assessed by ultrasound imaging and intensity analysis. Compared to most other echogenic liposome formulations reported, our method is easier, faster, and more economical. It would be useful for many applications with improvements and optimization. PMID:17281108

Liu, Rui; Wei, Xiaohui; Yao, Yanbin; Chai, Qiliang; Chen, Yue; Xu, Yuhong

2005-01-01

271

Size Dependence of Protein-Induced Flocculation of Phosphatidylcholine Liposomes.  

PubMed

The adsorption of lysozyme and cytochrome C on phosphatidylcholine liposomes essentially changes the physical properties of the phospholipid membranes and under certain circumstances greatly affects the stability of the colloid dispersion by inducing bridging liposome flocculation. This study was designed to examine experimentally the influence of liposome size on two kinetic parameters of the flocculation, its rate constant and activation energy. As the liposome radius increased in the range 50-500 nm, the activation energy tended to decrease, resulting in an increased flocculation rate, except for the flocculation of 400-nm liposomes, which was greatly impeded. The pronounced influence of the liposome size on the flocculation rate constant was evident, since a well-defined minimum in the kinetic rate of flocculation of 400-nm liposomes was detected experimentally. The obtained nonlinear radius dependencies of the flocculation rates and activation energies are interpreted in terms of the bridging mechanism of the protein-induced liposome flocculation and the supplementary concept of the stability of thin liquid films formed between approaching protein-adsorbed liposomes. Copyright 2000 Academic Press. PMID:11401344

Dimitrova, Mariana N.; Tsekov, Roumen; Matsumura, Hideo; Furusawa, Kunio

2000-06-01

272

Triggering liposomal drug release with a lysosomotropic agent.  

PubMed

Drug release from liposomes in the endosome-lysosomal organelles into cytoplasm is critical to cytotoxicity and anticancer effects. Chloroquine is a lysosomotropic agent that has been reported to enhance in vitro cytotoxicity of basic anticancer drugs. To investigate the mechanism of chloroquine triggering basic anticancer drugs release from liposomes and the potential to treat solid tumors in clinic, daunorubicin was loaded into folate-targeted liposomes by ammonium sulfate remote loading method. In vitro triggered release profiles showed that chloroquine can instantly expel about 11% daunorubicin out of liposomes. In vitro cytotoxicity of folate-targeted liposomal daunorubicin on L1210JF(FR+) was enhanced by chloroquine, which was further confirmed by confocal micrographs. Intraliposomal pH was increased by adding chloroquine into 8-hydroxypyrene-1,3,6-trisulfonic acid trisodium salt (HPTS) liposomes with ammonium sulfate gradient, but was not higher than 5.5. Ion exchange and pH rising are the most plausible mechanisms of chloroquine triggering daunorubicin release from liposomes. In vivo anticancer effects on a murine solid tumor model with L1210JF indicated that chloroquine induced daunorubicin release from liposomes as well. Overall, these results support the potential application of chloroquine to trigger the release of liposomal drugs and ultimately to improve the therapeutic efficacy. PMID:20821395

Xiong, Subin; Li, Hong; Yu, Bo; Wu, Jun; Lee, Robert J

2010-12-01

273

Liposome-encapsulated dexamethasone attenuates ventilator-induced lung inflammation  

PubMed Central

BACKGROUND AND PURPOSE Systemic glucocorticoid therapy may effectively attenuate lung inflammation but also induce severe side-effects. Delivery of glucocorticoids by liposomes could therefore be beneficial. We investigated if liposome-encapsulated dexamethasone inhibited ventilator-induced lung inflammation. Furthermore, we evaluated whether targeting of cellular Fc?-receptors (Fc?Rs) by conjugating immunoglobulin G (IgG) to liposomes, would improve the efficacy of dexamethasone-liposomes in attenuating granulocyte infiltration, one of the hallmarks of lung inflammation. EXPERIMENTAL APPROACH Mice were anaesthetized, tracheotomized and mechanically ventilated for 5 h with either ‘low’ tidal volumes ?7.5 mL·kg?1 (LVT) or ‘high’ tidal volumes ?15 mL·kg?1 (HVT). At initiation of ventilation, we intravenously administered dexamethasone encapsulated in liposomes (Dex-liposomes), dexamethasone encapsulated in IgG-modified liposomes (IgG-Dex-liposomes) or free dexamethasone. Non-ventilated mice served as controls. KEY RESULTS Dex-liposomes attenuated granulocyte infiltration and IL-6 mRNA expression after LVT-ventilation, but not after HVT-ventilation. Dex-liposomes also down-regulated mRNA expression of IL-1? and KC, but not of CCL2 (MCP-1) in lungs of LVT and HVT-ventilated mice. Importantly, IgG-Dex-liposomes inhibited granulocyte influx caused by either LVT or HVT-ventilation. IgG-Dex-liposomes diminished IL-1? and KC mRNA expression in both ventilation groups, and IL-6 and CCL2 mRNA expression in the LVT-ventilated group. Free dexamethasone prevented granulocyte influx and inflammatory mediator expression induced by LVT or HVT-ventilation. CONCLUSIONS AND IMPLICATIONS Fc?R-targeted IgG-Dex-liposomes are pharmacologically more effective than Dex-liposomes particularly in inhibiting pulmonary granulocyte infiltration. IgG-Dex-liposomes inhibited most parameters of ventilator-induced lung inflammation as effectively as free dexamethasone, with the advantage that liposome-encapsulated dexamethasone will be released locally in the lung thereby preventing systemic side-effects.

Hegeman, MA; Cobelens, PM; Kamps, JAAM; Hennus, MP; Jansen, NJG; Schultz, MJ; van Vught, AJ; Molema, G; Heijnen, CJ

2011-01-01

274

Adsorbed liposome deformation studied with quartz crystal microbalance  

NASA Astrophysics Data System (ADS)

Deformation of surface-adsorbed liposomes is an important parameter that governs the kinetics of their transformations, but one that is very difficult to measure in the case of nm-size liposomes. We investigate the deformation of dimyristoyl phosphatidyl choline liposomes by quartz crystal microbalance (QCM) as a function of temperature and show that it follows the dependence of this lipid's bending modulus on temperature, as expected from theoretical considerations. To corroborate our approach, we model QCM response from adsorbed liposomes by explicitly considering their shape and mechanical properties.

Reviakine, Ilya; Gallego, Marta; Johannsmann, Diethelm; Tellechea, Edurne

2012-02-01

275

Studies on pectin coating of liposomes for drug delivery.  

PubMed

The present study investigated the surface coating of charged liposomes by three different types of pectin (LM, HM and amidated pectin) by particle size determinations and zeta potential measurements. The pectins and the pectin coated liposomes were visualized by atomic force microscopy. The adsorption of pectin onto positive liposomes yielded a reproducible increase in particle size and a shift of the zeta potential from positive to negative side for all three pectin types, whereas the adsorption of pectin onto negative liposomes did not render any significant changes probably due to electrostatic repulsion. The positive liposomes coated with HM-pectin gave the largest pectin coated particles with the least negative zeta potential, while the opposite was observed for the LM-pectin coated positive liposomes. Furthermore, results from dynamic light scattering revealed narrow size distributions, indicating that the degree of aggregation was low for the pectin coated liposomes. As liposomes are able to encapsulate drugs and pectin has been found to be mucoadhesive, these pectin coated liposomes may be potential drug delivery systems. PMID:21862293

Nguyen, Sanko; Alund, Siv Jorunn; Hiorth, Marianne; Kjøniksen, Anna-Lena; Smistad, Gro

2011-08-06

276

Predicting skin permeability using liposome electrokinetic chromatography.  

PubMed

The potential of liposome electrokinetic chromatography (LEKC), which is applied to estimate compound penetration through the skin, was evaluated in this report. Quantitative retention-activity relationships (QRARs) were successfully constructed between the compound skin permeability coefficient (log K(p)) and the retention values (log k), as well as some calculated molecular descriptors by the stepwise regression method (R(2) = 0.902). Furthermore, the developed vector method was applied to compare the similarity between the reported lipophilicity measuring scales and compounds through the skin. Both results indicated that the transport of a compound into the liposomal membrane was more similar to its penetration through the skin than that into other systems including the octanol-water system. In a word, LEKC is a promising simple method to predict drug penetration through the skin. PMID:19173048

Wang, Yongjun; Sun, Jin; Liu, Hongzhuo; Liu, Jianfang; Zhang, Liqiang; Liu, Kai; He, Zhonggui

2008-10-24

277

Liposome-encapsulated photosensitizers against bacteria.  

PubMed

Photodynamic therapy (PDT), utilizing photosensitizers and light, has received considerable interests for its potential to treat microbial infections. The advantages of antimicrobial PDT include a broad spectrum of action, efficient killing against wild-type as well as drug-resistant pathogens. Therefore, antimicrobial PDT could be valuable to rapidly reduce the microbial burden during the management of local infections, especially for the antibiotic resistance. A variety of photosensitizers have been examined its efficacy against pathogens. To increase the efficacy of photosensitizers, various drug delivery systems have been developed. Among these carrier systems, liposomes showed their PDT efficacy and safety in delivering photosensitizers. This review is focused on the application of liposomes mediated photodynamic inactivation of bacteria along with the discussion of few of recent patents. PMID:23550544

Chen, Chin- Tin; Chen, Chueh- Pin; Yang, Jen- Chang; Tsai, Tsuimin

2013-08-01

278

Interaction of fluoxetine with phosphatidylcholine liposomes  

Microsoft Academic Search

Fluoxetine (Prozac) is one of the latest of a new generation of antidepressants, approved by FDA in 2002.The interactions of fluoxetine with multilamellar liposomes of pure phosphatidylcholine (PC) or containing cholesterol 10% molar were studied as a function of the lipid chain lengths, using differential scanning calorimetry and spin labelling EPR techniques.The DSC profiles of the gel-to-fluid state transition of

Federico Momo; Sabrina Fabris; Roberto Stevanato

2005-01-01

279

Biophysical studies on chitosan-coated liposomes  

Microsoft Academic Search

Liposomes have been used as delivery vehicles for stabilizing drugs, overcoming barriers to cellular and tissue uptake, and\\u000a for directing their contents toward specific sites in vivo. Chitosan is a biological macromolecule derived from crustacean\\u000a shells and has several emerging applications in drug development, obesity control, and tissue engineering. In the present\\u000a work, the interaction between chitosan and dipalmitoyl phosphatidylcholine

Mohsen M. Mady; Mirhane M. Darwish; Safaa Khalil; Wafaa M. Khalil

2009-01-01

280

Liposomal Simvastatin Attenuates Neointimal Hyperplasia in Rats  

Microsoft Academic Search

Monocytes, macrophages, and inflammation play a key role in the process of neointimal proliferation and restenosis. The present\\u000a study evaluated whether systemic and transient depletion of monocytes could be obtained by a single intravenous (IV) injection\\u000a of simvastatin liposomes, for the inhibition of neointima formation. Balloon-injured carotid artery rats (n?=?30) were randomly assigned to treatment groups of free simvastatin, simvastatin

Eyal Afergan; Meital Ben David; Hila Epstein; Nickolay Koroukhov; Dalia Gilhar; Keren Rohekar; Haim D. Danenberg; Gershon Golomb

2010-01-01

281

Oxygen Measurements in Liposome Encapsulated Hemoglobin  

NASA Astrophysics Data System (ADS)

Liposome encapsulated hemoglobins (LEH's) are of current interest as blood substitutes. An analytical methodology for rapid non-invasive measurements of oxygen in artificial oxygen carriers is examined. High resolution optical absorption spectra are calculated by means of a one dimensional diffusion approximation. The encapsulated hemoglobin is prepared from fresh defibrinated bovine blood. Liposomes are prepared from hydrogenated soy phosphatidylcholine (HSPC), cholesterol and dicetylphosphate using a bath sonication method. An integrating sphere spectrophotometer is employed for diffuse optics measurements. Data is collected using an automated data acquisition system employing lock-in -amplifiers. The concentrations of hemoglobin derivatives are evaluated from the corresponding extinction coefficients using a numerical technique of singular value decomposition, and verification of the results is done using Monte Carlo simulations. In situ measurements are required for the determination of hemoglobin derivatives because most encapsulation methods invariably lead to the formation of methemoglobin, a nonfunctional form of hemoglobin. The methods employed in this work lead to high resolution absorption spectra of oxyhemoglobin and other derivatives in red blood cells and liposome encapsulated hemoglobin (LEH). The analysis using singular value decomposition method offers a quantitative means of calculating the fractions of oxyhemoglobin and other hemoglobin derivatives in LEH samples. The analytical methods developed in this work will become even more useful when production of LEH as a blood substitute is scaled up to large volumes.

Phiri, Joshua Benjamin

282

Integration of ?-carotene molecules in small liposomes  

NASA Astrophysics Data System (ADS)

The most typical feature of carotenoids is the long polyene chain with conjugated double bonds suggesting that they can serve as conductors of electrons, acting as ''molecular wires'', important elements in the molecular electronic devices. Carotenoids are essential components of photosynthetic systems, performing different functions as light harvesting, photoprotection and electron transfer. They act also as natural antioxidants. In addition they perform structural role stabilizing the three-dimensional organization of photosynthetic membranes. Carotenoids contribute to the stability of the lipid phase, preserving the membrane integrity under potentially harmful environmental conditions. Carotenoids can be easily integrated into model membranes, facilitating the investigation of their functional roles. In carotenoid-egg phosphatidylcholine (EPC) liposomes ß-carotene is randomly distributed in the hydrocarbon interior of the bilayer, without any preferred, well defined orientation and retains a substantial degree of mobility. Here we investigate the degree of integration of ß-carotene in small unilamellar EPC liposomes and the changes in ß-carotene absorption and Raman spectra due to the lipid-pigment interaction. All observed changes in ß-carotene absorption and Raman spectra may be regarded as a result of the lipid-pigment interactions leading to the polyene geometry distortion and increasing of the environment heterogenety in the liposomes as compared to the solutions.

Andreeva, Atanaska; Popova, Antoaneta

2010-11-01

283

Liposomal architecture boosts biocompatibility of nanohybrid cerasomes.  

PubMed

Biomimetic cerasome has drawn much attention as a novel drug delivery system because its atomic layer of polyorganosiloxane surface imparts higher morphological stability than conventional liposomes and its liposomal bilayer structure reduces the overall rigidity and density greatly compared to silica nanoparticles. But, the issues about the interactions between cerasomes and biological systems have not been addressed as far as we could find. Herein, we reported cellular uptake of cerasomes and their biological effects toward human umbilical vein endothelial cells (HUVECs) compared with silica nanoparticles. The results indicated that the uptake of cerasomes by HUVECs was a concentration-, time-, and energy-dependent process and occurred probably through a process of clathrin-mediated endocytosis, which resulted in rearrangement of the cell cytoskeleton. Cerasomes affected different aspects of cell function to a smaller extent than silica nanoparticles, including cell proliferation, cell cycle, cell apoptosis, endogenous ROS level and pro-inflammatory molecular expression. In a word, cerasomes are more biocompatible than silica nanoparticles due to the incorporation of the liposomal architecture into cerasomes. The preliminary data will assist in the further development of new cerasome-based delivery systems. PMID:21261456

Ma, Yan; Dai, Zhifei; Gao, Yanguang; Cao, Zhong; Zha, Zhengbao; Yue, Xiuli; Kikuchi, Jun-Ichi

2011-01-24

284

Photoinduced electron and energy transfer in a new porphyrin phthalocyanine triad  

NASA Astrophysics Data System (ADS)

Complexes of porphyrins, phthalocyanines, and chlorophylls are well suited for modelling both the electron and energy transfer processes in photosynthetic reaction centers and natural chlorophyll complexes. In the present paper, we report the synthesis and photophysical characterization of a novel tetraphenylporphyrin silicon(IV) phthalocyanine triad, where two porphyrins are linked to the central silicon atom of a phthalocyanine moiety. It has been found that the photophysical properties of the triad (Tr) are strongly affected by two different types of interactions between the porphyrin (P) and the phthalocyanine (Pc) parts of Tr, namely excitation energy transfer (EET) and photoinduced electron transfer (ET). The first one results in appearance of the Pc fluorescence when the P-part was initially excited and plays dominant role in fast depopulation of the first excited singlet state of the P moiety. Another competitive process in quenching of P-part fluorescence is electron transfer, but the probability of it is six times less compared to that of EET. If the first excited singlet state of the Pc-part is populated (directly or via EET), it undergoes fast depopulation via ET to the charge-separated state. As a result, the fluorescence quantum yield of the Pc-part of Tr is approximately three orders of magnitude less compared to that of silicon(IV) phthalocyanine with two axial poly(ethylene glycol) chains (SiPc) used as a reference. Analysis of transient absorption data has shown that charge-recombination occurs with a decay time of 30 ps directly to the ground state.

Ermilov, Eugeny A.; Tannert, Sebastian; Werncke, Thomas; Choi, Michael T. M.; Ng, Dennis K. P.; Röder, Beate

2006-09-01

285

Interaction of liposomal formulations of meta-tetra(hydroxyphenyl)chlorin (temoporfin) with serum proteins: protein binding and liposome destruction.  

PubMed

mTHPC is a non polar photosensitizer used in photodynamic therapy. To improve its solubility and pharmacokinetic properties, liposomes were proposed as drug carriers. Binding of liposomal mTHPC to serum proteins and stability of drug carriers in serum are of major importance for PDT efficacy; however, neither was reported before. We studied drug binding to human serum proteins using size-exclusion chromatography. Liposomes destruction in human serum was measured by nanoparticle tracking analysis (NTA). Inclusion of mTHPC into conventional (Foslip(®)) and PEGylated (Fospeg(®)) liposomes does not affect equilibrium serum protein binding compared with solvent-based mTHPC. At short incubation times the redistribution of mTHPC from Foslip(®) and Fospeg(®) proceeds by both drug release and liposomes destruction. At longer incubation times, the drug redistributes only by release. The release of mTHPC from PEGylated vesicles is delayed compared with conventional liposomes, alongside with greatly decreased liposomes destruction. Thus, for long-circulation times the pharmacokinetic behavior of Fospeg(®) could be influenced by a combination of protein- and liposome-bound drug. The study highlights the modes of interaction of photosensitizer-loaded nanovesicles in serum to predict optimal drug delivery and behavior in vivo in preclinical models, as well as the novel application of NTA to assess the destruction of liposomes. PMID:22607362

Reshetov, Vadzim; Zorin, Vladimir; Siupa, Agnieszka; D'Hallewin, Marie-Ange; Guillemin, François; Bezdetnaya, Lina

2012-07-09

286

Paramagnetic liposomes as MRI contrast agents: influence of liposomal physicochemical properties on the in vitro relaxivity  

Microsoft Academic Search

The in vitro contrast efficacy of liposome encapsulated gadolinium-[10-(2-hydroxypropyl)-1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid] (GdHPDO3A) has been assessed by relaxometry. The internal concentrations were 150 and 250 mM Gd. Two types of liposome compositions were investigated: a phospholipid blend consisting of both hydrogenated phosphatidylcholine (HPC) and phosphatidylserine (HPS) with a gel-to-liquid crystalline phase transition temperature (Tm) of 50°C, and a mixture of dipalmitoylphosphatidylcholine (DPPC)

Sigrid L. Fossheim; Anne Kjersti Fahlvik; Jo Klaveness; Robert N. Muller

1999-01-01

287

Differently substituted phthalocyanines: Comparison of calculated energy levels, singlet oxygen quantum yields, photo-oxidative stabilities, photocatalytic and catalytic activities  

Microsoft Academic Search

Zinc(II) and cobalt(II) phthalocyanines bearing different electron-donating or -withdrawing substituents were prepared. The following properties of these phthalocyanines were investigated: singlet oxygen quantum yields, photo-oxidative stabilities, photocatalytic activities (photooxidation of (S)-(?)-citronellol) and catalytic activities (oxidation of 2-mercaptoethanol). Furthermore, the positions of HOMO\\/LUMO energy levels of the ground state (S0), first excited singlet state (S1) and first excited triplet state (T1)

Hiromi Shinohara; Olga Tsaryova; Günter Schnurpfeil; Dieter Wöhrle

2006-01-01

288

Synthesis, photophysical and photochemical properties of highly soluble phthalocyanines substituted with four 3,5-dimethylpyrazole-1-methoxy groups  

Microsoft Academic Search

The synthesis and characterization of new peripherally tetra-3,5-dimethylpyrazole-1-methoxy substituted metal-free (4), zinc (5), nickel (6), cobalt (7), copper (8) and lead (9) phthalocyanines are described for the first time in this study. The photophysical (fluorescence quantum yields and fluorescence lifetimes) and photochemical (photodegradation and singlet oxygen quantum yields) properties of metal-free (4), zinc (5) and lead (9) phthalocyanines are studied

R?za Bayrak; Hakk? Türker Akçay; Mahmut Durmu?; ?smail De?irmencio?lu

2011-01-01

289

Kinetic of the Intracellular Incorporation of New Phthalocyanines Synthesized in mexico and Its Potential as Photosensibilizers in the Photodynamic Therapy  

SciTech Connect

The search of more specific and efficient photosensitizer in low oxygen tensions is a need in the Photodynamic Therapy (PDT). Phthalocyanines have demonstrated to have the above mentioned activity. The aim of this work was to determine the efficiency of PDT using two phthalocyanines synthesized in Mexico to eliminate melanoma cells. B16F0 melanoma mouse cells were exposed to concentrations from 8.95x10{sup -5} to 0.733 m/mL of F16VoPc and F16NbPcC13 during 24h, afterwards cellular mortality was measured. One kinetic was realized to determine the intracellular incorporation of phthalocyanines by confocal microscopy at 1, 2, 4, 8, 16 and 24 h of exposition. The PDT was applied exposing the cells to innocuous concentration (that does not provoke cellular death with out irradiation) and irradiating with an argon laser at 100 J/cm{sup 2}. For each phthalocyanine a control group was used; one group was not treated neither with light nor with phthalocyanine, the other group it was only irradiated. 24 h after treatment the citotoxicity was measured by Alamar blue assay. The innocuous concentration found for the phthalocyanines F16VoPc and F16NbPcC13 were 4.58x10-2 and 2.29xl0{sup -2} mg/mL, respectively. The time of maximum intracellular accumulation for both phthalocyanines was 24 h. Only the F16VoPc had anticancerous activity and induced 31.7% of cellular death. The PDT might offer a potential alternative to the treatment of this cancer when is used the phthalocyanine F16VoPc.

Aragon-Aguilar, Hector; Ramon-Gallegos, Eva; Arenas-Huertero, Francisco Jesus [Departamento de Morfologia, ENCB, Institute Politecnico Nacional. Carpio y Plan de Ayala S/N. Col. Sto Tomas. Mexico, D.F. C.P. 11340 (Mexico); Contreras-Ramos, Alejandra [Hospital Infantil de Mexico (Mexico); Cruz-Orea, Alfredo [Depto. de Fisica, CINVESTAV-IPN, unidad Zacatenco, Mexico, D.F. (Mexico); Sosa-Sanchez, Jose Luis; Garcia Miranda, Maribel [Universidad Autonoma de Puebla. Blvd. 14 Sur y Ave. San Claudio, Edificio 137 Ciudad Universitaria, Col. San Manuel, Puebla, Puebla (Mexico)

2008-08-11

290

Efficient photodegradation of 2,4-dichlorophenol in aqueous solution catalyzed by polydivinylbenzene-supported zinc phthalocyanine  

Microsoft Academic Search

In this study, photodegradation of 2,4-dichlorophenol (2,4-DCP) in aerated aqueous solution at pH 13 in the presence of hydrogen peroxide catalyzed by polydivinylbenzene-supported zinc phthalocyanine (PDVB-ZnPc) prepared from chloromethylated polydivinylbenzene and zinc phthalocyanine via a Friedel–Crafts reaction has been investigated. The reaction intermediates were identified by gas chromatography–mass spectrometry (GC–MS). The reactive oxygen species involved in the reaction were determined

Lin Wu; Aimin Li; Guandao Gao; Zhenghao Fei; Shirong Xu; Quanxing Zhang

2007-01-01

291

The preparation and modification of phthalocyanine containing materials  

NASA Astrophysics Data System (ADS)

Phthalocyanines (Pcs) are highly conjugated, 18 pi-electron cyclic molecules composed of four isoindoline units that exhibit unique optical, electrical and chemical properties. While originally used as dyes and pigments, the use of Pcs in modern technology has increased dramatically due to improved understanding and processing capabilities. Work in this dissertation outlines a number of methods to prepare Pc-containing materials for use in various applications. Chapter 1 provides a brief review of methods used to prepare Pc-containing polymeric materials from both symmetric and asymmetric macrocycles. Discussion will focus on methods that incorporate symmetric Pcs as the focal point, with particular attention being paid to the influence of the peripheral substitution of the Pc on macromolecular structure and properties. Further discussion will focus on the utilization of asymmetric Pcs as auxiliary functionalities, such as at the terminus or as pendant groups, of larger macromolecular materials. Chapter 2 describes the preparation of linear Pc-containing polymers through ring-opening metathesis polymerization of a Pc monomer. Through proper selection of catalyst, well-defined polymers with Pcs as pendant groups were prepared. Due to the controlled nature of ROMP, polymers of varying architectures, composition, and size were synthesized. The effect of Pc metallation, polymer composition and architecture on the site-isolation of the chromophore was investigated in both solution and condensed-phase thin films. Chapter 3 reports on efforts to prepare linear polymers with companion functionalities for post-polymerization coupling of asymmetric Pcs. Polymers with pendant furan groups were prepared for coupling with asymmetric Pcs through Diels-Alder cycloaddition. Investigation indicated that while coupling was achievable, the presence of the Pc in the resultant polymer promoted undesired crosslinking when stored at ambient conditions in light. Attempts to mitigate this problem through alternation of functionality locations were attempted by placing the furan functionality on the Pc, but degradation of the furan occurred to quickly to perform coupling sufficiently. Chapter 4 discusses the preparation of Pc-containing networks through Diels-Alder cycloaddition of furan and maleimide containing tetrasubstituted Pcs. Following preparation of the various Pcs, network formation in various states was conducted including solution, molded thick films, and patterned assemblies. Chapter 5 summarizes the results presented in Chapters 2-4 and provides an outlook for some future directions based upon the work herein. In addition, some preliminary results of some of these directions will also be presented.

Korth, Bryan D.

292

Elastic liposomes mediated transcutaneous immunization against Hepatitis B  

Microsoft Academic Search

Transcutaneous immunization presents a major challenge due to poor permeability of antigens through the skin barrier. To overcome this limitation ultradeformable lipid vesicles, the elastic liposomes, could be a better module for transcutaneous delivery of these proteinaceous antigens. In the present investigation Hepatitis B surface antigen (HBsAg)-loaded elastic liposomes were utilized as a mode for enhanced immunity against the antigen.

Dinesh Mishra; Vaibhav Dubey; Abhay Asthana; D. K. Saraf; N. K. Jain

2006-01-01

293

Liposomal drug delivery systems: from concept to clinical applications.  

PubMed

The first closed bilayer phospholipid systems, called liposomes, were described in 1965 and soon were proposed as drug delivery systems. The pioneering work of countless liposome researchers over almost 5 decades led to the development of important technical advances such as remote drug loading, extrusion for homogeneous size, long-circulating (PEGylated) liposomes, triggered release liposomes, liposomes containing nucleic acid polymers, ligand-targeted liposomes and liposomes containing combinations of drugs. These advances have led to numerous clinical trials in such diverse areas as the delivery of anti-cancer, anti-fungal and antibiotic drugs, the delivery of gene medicines, and the delivery of anesthetics and anti-inflammatory drugs. A number of liposomes (lipidic nanoparticles) are on the market, and many more are in the pipeline. Lipidic nanoparticles are the first nanomedicine delivery system to make the transition from concept to clinical application, and they are now an established technology platform with considerable clinical acceptance. We can look forward to many more clinical products in the future. PMID:23036225

Allen, Theresa M; Cullis, Pieter R

2012-10-01

294

Nerve growth factor-mediated targeting of liposomes to cells  

SciTech Connect

Derivatives of beta-nerve growth factor (NGF), modified by biotinylation of carboxyl groups, were used to target the specific binding of liposomes to cultured rat and human cells bearing NGF receptors. Streptavidin was conjugated via peptide bonds to amino groups on liposomes. Biotinylated NGF, but not unmodified NGF, mediated the binding of radiolabeled streptavidin-liposomes to rat pheochromocytoma PC12 cells in suspension at 4/sup 0/C. In contrast, biotinylated NGF did not increase the binding of hemoglobin-conjugated liposomes tested as a control for specificity. Biotinylated NGF also mediated the specific binding of streptavidin-liposomes containing fluorescein isothiocyanate-labeled dextran to PC12 cells and human melanoma HS294 cells. When HS294 cells were incubated at 37/sup 0/C following liposome binding at 4/sup 0/C, the cell-associated fluorescence appeared to become internalized, in that some cells displayed a perinuclear pattern of fluorescence similar to that observed when lysosomes were stained with acridine orange. Trypsin treatment abolished cell-associated fluorescence when cells were held at 4/sup 0/C but did not affect the fluorescence in cells following incubation at 37/sup 0/C. When liposomes containing carboxyfluorescein, a dye that can diffuse out of acidic compartments, were targeted to HS294 cells, incubation at 37/sup 0/C resulted in diffuse cytoplasmic fluorescence, suggesting that internalized liposomes encounter lysosomal or prelysosomal organelles.

Hawrot, E.; Rosenberg, M.B.; Preston, P.E.; Breakefield, X.O.

1986-05-01

295

Optically guided controlled release from liposomes with tunable plasmonic nanobubbles  

Microsoft Academic Search

A new method of optically guided controlled release was experimentally evaluated with liposomes containing a molecular load and gold nanoparticles (NPs). NPs were exposed to short laser pulses to induce transient vapor bubbles around the NPs, plasmonic nanobubbles, in order to disrupt the liposome and eject its molecular contents. The release efficacy was tuned by varying the lifetime and size

Lindsey J. E. Anderson; Eric Hansen; Ekaterina Y. Lukianova-Hleb; Jason H. Hafner; Dmitri O. Lapotko

2010-01-01

296

Enhanced efficacy of anti-tumor liposomal doxorubicin by hyperthermia  

Microsoft Academic Search

The efficiency of novel tumor chemotherapeutics could be increased using targeted drug delivery by hyperthermia. In this paper, the 3D liposomal doxorubicin distribution in the tumor tissue enhanced by local hyperthermia was quantitatively studied in real time using laser confocal microscopy. Results showed that the thermally induced liposomal doxorubicin extravasation was non-uniform and more excessive in the peripheral region than

Ping Liu; Lisa Xuemin Xu; Aili Zhang

2006-01-01

297

Liposomal antibiotics for the treatment of infectious diseases.  

PubMed

Introduction: Liposomal delivery systems have been utilized in developing effective therapeutics against cancer and targeting microorganisms in and out of host cells and within biofilm community. The most attractive feature of liposome-based drugs are enhancing therapeutic index of the new or existing drugs while minimizing their adverse effects. Areas covered: This communication provides an overview on several aspects of liposomal antibiotics including the most widely used preparation techniques for encapsulating different agents and the most important characteristic parameters applied for examining shape, size and stability of the spherical vesicles. In addition, the routes of administration, liposome-cell interactions and host parameters affecting the biodistribution of liposomes are highlighted. Expert opinion: Liposomes are safe and suitable for delivery of variety of molecules and drugs in biomedical research and medicine. They are known to improve the therapeutic index of encapsulated agents and reduce drug toxicity. Recent studies on liposomal formulation of chemotherapeutic and bioactive agents and their targeted delivery show liposomal antibiotics potential in the treatment of microbial infections. PMID:23886421

Alhariri, Moayad; Azghani, Ali; Omri, Abdelwahab

2013-07-26

298

Liposomes and skin: From drug delivery to model membranes  

Microsoft Academic Search

The early eighties saw the introduction of liposomes as skin drug delivery systems, initially promoted primarily for localised effects with minimal systemic delivery. Subsequently, a novel ultradeformable vesicular system (termed “Transfersomes” by the inventors) was reported for transdermal delivery with an efficiency similar to subcutaneous injection. Further research illustrated that the mechanisms of liposome action depended on the application regime

G. M. El Maghraby; B. W. Barry; A. C. Williams

2008-01-01

299

Caspofungin and Liposomal Amphotericin B Therapy of Experimental Murine Scedosporiosis  

PubMed Central

Immunosuppressed mice were infected intravenously with conidia of Scedosporium prolificans. Treatment was begun 1 day later with liposomal amphotericin B, caspofungin, or both drugs initiated concurrently. Amphotericin B and caspofungin were each effective, but combined therapy did not appear to offer advantages over liposomal amphotericin B alone.

Bocanegra, Rosie; Najvar, Laura K.; Hernandez, Steve; McCarthy, Dora I.; Graybill, John R.

2005-01-01

300

Optimization of gatifloxacin liposomal hydrogel for enhanced transcorneal permeation.  

PubMed

The aim of this study was to prepare and characterize a topically effective prolonged-release ophthalmic gatifloxacin liposomal hydrogel formulation. Reverse-phase evaporation was used for the preparation of liposomes consisting of phosphatidylcholine (PC) and cholesterol (CH). The effect of PC:CH molar ratio on the percentage of drug encapsulated was investigated. The effect of additives, such as stearylamine (SA) or dicetyl phosphate (DP), as positive and negative charge inducers, respectively, was studied. Morphology, mean size, encapsulation efficiency, and in vitro release of gatifloxacin from liposomes were evaluated. For hydrogel preparation, carbopol 940 was applied. In vitro transcorneal permeation through excised albino rabbit cornea was also determined. Optimal encapsulation efficiency was found at the 5:3 PC:CH molar ratio; by increasing CH content above this limit, the encapsulation efficiency decreased. Positively charged liposomes showed superior entrapment efficiency over other liposomes. Hydrogel-containing liposomes with lipid content PC, CH, and SA in a molar ratio of 5:3:1, respectively, showed best release and transcorneal permeation. These results suggest that the encapsulation of gatifloxacin into liposomes prolonged the in vitro release, depending on composition of the vesicles. In addition, the polymer hydrogel used in the preparation ensured steady, prolonged transcorneal permeation. In conclusion, gatifloxacin liposomal hydrogel is a suitable delivery system for the improvement of the ocular bioavailability of gatifloxacin. PMID:19545203

Hosny, Khaled Mohamed

2010-03-01

301

DOTAP cationic liposomes prefer relaxed over supercoiled plasmids  

Microsoft Academic Search

Cationic liposomes and DNA interact electrostatically to form complexes called lipoplexes. The amounts of unbound (free) DNA in a mixture of cationic liposomes and DNA at different cationic lipid:DNA molar ratios can be used to describe DNA binding isotherms; these provide a measure of the binding efficiency of DNA to different cationic lipid formulations at various medium conditions. In order

Simcha Even-Chen; Yechezkel Barenholz

2000-01-01

302

Structural properties of liposomes from digital holographic microscopy  

NASA Astrophysics Data System (ADS)

We have constructed liposomes from L alpha Phosphatidylcholine (PC) lipids, which are biomimetic lipids similar to those present in the membranes of mammalian cells. We propose an advance in the use of liposomes, such as for drug delivery, to incorporate into the liposomal membranes transport proteins that have been extracted from the lipid membranes of mammalian cells. In this paper, we describe the usage of a novel optical microscope to characterize the nanomechanical properties of these liposomes. We have applied the technique of digital holographic microscopy, using an instrument recently developed at the University of Münster, Germany. This system enabled us to measure quantitatively the structural changes in liposomes. We have investigated the deformations of these biomimetic lipids comprising these liposomes by applying osmotic stresses, in order to gain insight into the membrane environment prior to incorporation of cloned membrane transport proteins. This control of the nanomechanical properties is important in the stresses transmitted to mechanosensitive ion channels that we have incorporated into the liposomal membranes. These liposomes provide transporting vesicles that respond to mechanical stresses, such as those that occur during implantation.

Di Maio, Isabelle L.; Carl, Daniel; Langehanenberg, Patrik; Valenzuela, Stella M.; Battle, Andrew R.; Al Khazaaly, Sabah; Killingsworth, Murray; Kemper, Bjorn; von Bally, Gert; Martin, Donald K.

2006-01-01

303

Nutrient Uptake by Protocells: A Liposome Model System  

Microsoft Academic Search

Over the past decade, several liposome-basedmodels for protocells have been developed. Forexample, liposome systems composed of polymeraseenzymes encapsulated with their substrates havedemonstrated that complex compartmentalized reactionscan be carried out under conditions in which polymericproducts are protected from degradation by hydrolyticenzymes present in the external medium. However, suchsystems do not have nutrient uptake mechanisms, whichwould be essential for primitive cells lacking

Pierre-Alain Monnard; David W. Deamer

2001-01-01

304

Development of the Liposomes Entrapped Ultrasound Imaging Gas (``Bubble Liposomes'') as Novel Gene Delivery Carriers  

Microsoft Academic Search

Recently, microbubbles and ultrasound have been investigated with a view to improving the transfection efficiency of nonviral delivery systems for gene by cavitation. However, microbubbles had some problems in terms of stability and targeting ability. To solve these problems, we paid attention to liposomes that had many advantages such as stable and safe in vivo and easy to modify targeting

Ryo Suzuki; Kumiko Tanaka; Kaori Sawamura; Tomoko Takizawa; Naoki Utoguchi; Yoichi Negishi; Kohsuke Hagisawa; Toshihiko Nishioka; Kazuo Maruyama

2006-01-01

305

[Immunogenic properties of the liposomal form of Pseudomonas aeruginosa anatoxin].  

PubMed

Studies of immunogenic properties of P. aeruginosa anatoxin incorporated into liposomes of varying lipid compositions have shown that single immunization of mice with the anatoxin included into phosphatidyl ethanolamine and lecithin cholesterol liposomes induces a 6-8-fold higher antitoxin antibodies production than immunization with unadsorbed or adsorbed on aluminum hydroxide P. aeruginosa toxoid. The maximal production of antibodies against exotoxin A of P. aeruginosa is observed already on the 14th day. The adjuvant properties of lecithin-cholesterol liposomes were revealed only in the primary immune response, while phosphatidyl ethanolamine-containing liposomes exhibited the capacity for enhancing both the primary and the secondary immune responses. The use of liposomal P. aeruginosa anatoxin made of lipids varying in composition and charge is a promising trend of research aimed at designing new highly effective immunization preparations for P. aeruginosa infection prevention. PMID:2125778

Minukhin, V V; Brodinova, N S; Tsyganenko, A Ia; Ivanova, N N; Vasil'chenko, V N; Sennikov, G A

1990-01-01

306

Electromagnetic field triggered drug and chemical delivery via liposomes  

DOEpatents

The present invention relates to a system and to a method of delivering a drug to a preselected target body site of a patient, comprising the steps of encapsulating the chemical agent within liposomes, essentially temperature insensitive, i.e. not having a specific predetermined phase transition temperature within the specific temperature range of drug administration; administering the liposomes to the target body site; and subjecting the target body site to nonionizing electromagnetic fields in an area of the preselected target body in order to release the chemical agent from the liposomes at a temperature of between about +10 and 65 C. The invention further relates to the use of the liposomes to bind to the surface of or to enter target tissue or an organ in a living system, and, when subjected to a nonionizing field, to release a drug from the liposomes into the target site.

Liburdy, R.P.

1993-03-02

307

Recent Applications of Liposomes in Ophthalmic Drug Delivery  

PubMed Central

Liposomal formulations were significantly explored over the last decade for the ophthalmic drug delivery applications. These formulations are mainly composed of phosphatidylcholine (PC) and other constituents such as cholesterol and lipid-conjugated hydrophilic polymers. Liposomes are biodegradable and biocompatible in nature. Current approaches for topical delivery of liposomes are focused on improving the corneal adhesion and permeation by incorporating various bioadhesive and penetration enhancing polymers. In the case of posterior segment disorders improvement in intravitreal half life and targeted drug delivery to the retina is achieved by liposomes. In this paper we have attempted to summarize the applications of liposomes in the field of ophthalmic drug delivery by citing numerous investigators over the last decade.

Mishra, Gyan P.; Bagui, Mahuya; Tamboli, Viral; Mitra, Ashim K.

2011-01-01

308

Enhanced antitumor effect of novel dual-targeted paclitaxel liposomes  

NASA Astrophysics Data System (ADS)

A novel dual-targeted peptide containing an alpha V integrins specific ligand and a neuropilin-1 specific motif was developed which showed an increased specific targeting affinity to tumors. Active dual-targeted liposomes were then produced with this peptide and exhibited greater binding activity than single-targeted liposomes in vitro. Paclitaxel entrapped in this formulation greatly increased the uptake of paclitaxel in the targeting cells and significantly suppressed the growth of HUVEC and A549 cells compared with general paclitaxel injections (Taxol) and single-targeted paclitaxel liposomes. The treatment of tumor xenograft models with dual-targeted paclitaxel liposomes also resulted in better tumor growth inhibition than any other treatment groups. Therefore, the dual-targeted paclitaxel liposomes prepared in the present study might be a more promising drug for cancer treatment. Furthermore, the dual-targeting approach may produce synergistic effects that can be applied in the development of new targeted drug delivery systems.

Meng, Shuyan; Su, Bo; Li, Wei; Ding, Yongmei; Tang, Liang; Zhou, Wei; Song, Yin; Li, Heyan; Zhou, Caicun

2010-10-01

309

Chemotherapy with hybrid liposomes for lymphoma without drugs in vivo.  

PubMed

Hybrid liposomes composed of dimyristoylphosphatidylcholine (DMPC) and polyoxyethylene (n) dodecyl ether (C(12)(EO)(n), n=21 and 25) were prepared with the method of sonication. Clear solution of hybrid liposomes having hydrodynamic diameter of 80-100 nm could be maintained over 3 weeks. Hybrid liposomes induced apoptosis for human lymphoma (MOLT-4 and RAJI) cells in vitro. No toxicity was observed in the rats after intravenously injecting hybrid liposomes in vivo. We clearly demonstrated that a mouse model of lymphoma was established and prolonged survival was obtained in mice models of lymphoma after the treatment with hybrid liposomes without drugs in vivo. The results in this study should support the prolonged survival for patients with lymphoma in clinical applications. PMID:16574356

Nagami, Hideaki; Matsumoto, Yoko; Ueoka, Ryuichi

2006-03-06

310

Designing of 'intelligent' liposomes for efficient delivery of drugs.  

PubMed

The liposome- vesicles made by a double phospholipid layers which may encapsulate aqueous solutions- have been introduced as drug delivery vehicles due to their structural flexibility in size, composition and bilayer fluidity as well as their ability to incorporate a large variety of both hydrophilic and hydrophobic compounds. With time the liposome formulations have been perfected so as to serve certain purposes and this lead to the design of "intelligent" liposomes which can stand specifically induced modifications of the bilayers or can be surfaced with different ligands that guide them to the specific target sites. We present here a brief overview of the current strategies in the design of liposomes as drug delivery carriers and the medical applications of liposomes in humans. PMID:12611636

Voinea, Manuela; Simionescu, Maya

311

Sonosensitive dioleoylphosphatidylethanolamine-containing liposomes with prolonged blood circulation time of doxorubicin  

Microsoft Academic Search

Ultrasound sensitive (sonosensitive) liposomes represent a drug delivery system designed for releasing a drug load upon exposure to ultrasound (US). Inclusion of dioleoylphosphatidylethanolamine (DOPE) in liposome membranes was previously shown to induce sonosensitivity. Long blood circulation time of the liposomal drug is required for high tumour uptake and efficient US-mediated drug delivery. In this study, blood pharmacokinetics of DOPE-based liposomal

Tove J. Evjen; Eirik Hagtvet; Esben A. Nilssen; Martin Brandl; Sigrid L. Fossheim

2011-01-01

312

Tumor specific ultrasound enhanced gene transfer in vivo with novel liposomal bubbles  

Microsoft Academic Search

Bubble liposomes (liposomes which entrap an ultrasound imaging gas) may constitute a unique system for delivering various molecules efficiently into mammalian cells in vitro. In this study, Bubble liposomes were compared with cationic lipid (CL)–DNA complexes as potential gene delivery carriers into tumor in vivo. The delivery of genes by Bubble liposomes depended on the intensity of the applied ultrasound.

Ryo Suzuki; Tomoko Takizawa; Yoichi Negishi; Naoki Utoguchi; Kaori Sawamura; Kumiko Tanaka; Eisuke Namai; Yusuke Oda; Yasuhiro Matsumura; Kazuo Maruyama

2008-01-01

313

Nano or Submicron-Sized Liposomes as Carriers for Drug Delivery  

Microsoft Academic Search

Liposomes are tiny spheres ranging in diameters from 50 nm to several microns. The scope of this mini review is to introduce the concept of liposomes and to describe some aspects and mechanisms of stimulating topical and injectable products with liposomes. Two examples discussed in this article are topical delivery across skin and injectable formulations for anticancer drugs. Classic liposomes

Jia-You Fang

314

Hybrid ZnO/Phthalocyanine Photovoltaic Device with Highly Resistive ZnO Intermediate Layer.  

PubMed

We report a hybrid photovoltaic device composed of a 3.3 eV bandgap zinc oxide (ZnO) semiconductor and metal-free phthalocyanine layers and the effects of the insertion of the highly resistive ZnO buffer layer on the electrical characteristics of the rectification feature and photovoltaic performance. The hybrid photovoltaic devices have been constructed by electrodeposition of the 300 nm thick ZnO layer in a simple zinc nitrate aqueous solution followed by vacuum evaporation of 50-400 nm thick-phthalocyanine layers. The ZnO layers with the resistivity of 1.8 × 10(3) and 1 × 10(8) ? cm were prepared by adjusting the cathodic current density and were installed into the hybrid photovoltaic devices as the n-type and buffer layer, respectively. The phthalocyanine layers with the characteristic monoclinic lattice showed a characteristic optical absorption feature regardless of the thickness, but the preferred orientation changed depending on the thickness. The ZnO buffer-free hybrid 50 nm thick phthalocyanine/n-ZnO photovoltaic device showed a rectification feature but possessed a poor photovoltaic performance with a conversion efficiency of 7.5 × 10(-7) %, open circuit voltage of 0.041 V, and short circuit current density of 8.0 × 10(-5) mA cm(-2). The insertion of the ZnO buffer layer between the n-ZnO and phthalocyanine layers induced improvements in both the rectification feature and photovoltaic performance. The excellent rectification feature with a rectification ratio of 3188 and ideally factor of 1.29 was obtained for the hybrid 200 nm thick phthalocyanine/ZnO buffer/n-ZnO photovoltaic device, and the hybrid photovoltaic device possessed an improved photovoltaic performance with the conversion efficiency of 0.0016%, open circuit voltage of 0.31 V, and short circuit current density of 0.015 mA cm(-2). PMID:24016732

Izaki, Masanobu; Chizaki, Ryo; Saito, Takamasa; Murata, Kazufumi; Sasano, Junji; Shinagawa, Tsutomu

2013-09-23

315

Therapy of leishmaniasis: Superior efficacies of liposome-encapsulated drugs  

PubMed Central

Liposomes containing antimonial compounds trapped in the aqueous phase were tested in the treatment of experimental leishmaniasis. The rationale of this approach was based on the hypothesis that the liposomes and the parasite are taken up by the same cell, the reticuloendothelial cell, and we present electron microscopic evidence that supports this hypothesis. Suppression of leishmaniasis was quantified by determining the total number of parasites per liver from impression smears. When two antimonials, meglumine antimoniate and sodium stibogluconate, were encapsulated within liposomes, each was more than 700 times more active compared to either of the free (unencapsulated) drugs. After infection, if untreated, all of the hamsters eventually would die from the disease. Liposome-encapsulated meglumine antimoniate was about 330-640 times more effective in causing a drop in the death rate than was the free antimonial. The efficacy of treatment was influenced by the lipid composition and charge of the liposomes. For example, positively charged liposomes containing egg phosphatidylcholine were much less effective than negatively charged ones. In contrast, positively and negatively charged sphingomyelin liposomes were equally effective. Liposomes containing phosphatidylserine (which were negatively charged, but also had a much higher charge density) were among the less-effective preparations. Among those tested, the most consistently efficacious liposomes contained highly saturated long-chain phospholipids (eg., dipalmitoyl phosphatidylcholine), cholesterol, and a negative charge. We conclude that liposomes may be useful as carriers of drugs to treat infectious diseases involving the reticuloendothelial system. The toxicities of antimony are very similar to those of arsenic. Encapsulation of antimonial drugs and reduction of the dose required for effective therapy should minimize such systemic toxicities as acute cardiomyopathy and toxic nephritis. Images

Alving, Carl R.; Steck, Edgar A.; Chapman, Willie L.; Waits, Virginia B.; Hendricks, Larry D.; Swartz, Glenn M.; Hanson, William L.

1978-01-01

316

Analysis of individual lipoproteins and liposomes  

SciTech Connect

We describe the application of single molecule detection (SMD) technologies for the analysis of natural (serum lipoproteins) and synthetic (liposomes) transport systems. The need for advanced analytical procedures of these complex and important systems is presented with the specific enhancements afforded by SMD with flowing sample streams. In contrast to bulk measurements which yield only average values, measurement of individual species allows creation of population histograms from heterogeneous samples. The data are acquired in minutes and the analysis requires relatively small sample quantities. Preliminary data are presented from the analysis of low density lipoprotein, and multilamellar and unilamellar vesicles.

Robbins, D.L.; Keller, R.A.; Nolan, J.P. [and others

1997-08-01

317

Interaction of Phosphatidylserine-Phosphatidylcholine Liposomes with Sickle Erythrocytes  

PubMed Central

The sickle erythrocyte (RBC) is a pathologic RBC that contains multiple membrane abnormalities. Some of these abnormalities have been implicated in the pathophysiology of vasoocclusive crises characteristic of sickle cell disease; others have yet to be defined in terms of their clinical significance. Recent information has shown that sickle RBC adhere abnormally to cultured endothelial cells yet little is known about the ways in which sickle cells interact with model membranes of defined size and lipid composition. We investigated this phenomenon by interacting sickle RBC with artificial lipid vesicles (liposomes) containing acidic phospholipids. Our results demonstrate that sickle disease (hemoglobin SS) RBC bind more of these liposomes than do normal or sickle trait (hemoglobin AS) RBC and that these differences are accentuated by hypoxia-induced sickling. Binding of liposome phospholipid to sickled RBC was not attributable to phospholipid exchange between liposomes and RBC and was consistent with a mechanism involving both membrane fusion and a stable reversible adhesion of liposomes to the RBC membrane. Investigations into the mechanism(s) underlying increased liposome binding to sickled RBC suggested that the known reversible translocation of aminophospholipids, phosphatidylserine (PS) and phosphatidyl-ethanolamine (PE), from the inner to the outer leaflet of the reversibly sickled RBC (RSC) plasma membrane during sickling may be a component of increased liposome binding to RSC. This idea was supported from results of experiments in which normal RBC were treated with diamide resulting in the expression of outer leaflet PE and PS and a stimulation of liposome binding to these cells. However, sickle RBC separated according to cell density on stractan gradients showed that irreversibly sickled RBC (ISC) were less capable of liposome binding than were discoid RSC. Since ISC are known to contain elevated levels of outer leaflet aminophospholipids, such a result suggests that other changes in the plasma membrane of sickle cells, in addition to phospholipid reorganization, are probably involved in enhanced liposome binding to these cells. In other experiments, we showed that liposomes containing l-phenylalanine were capable of delivering this antisickling agent into intact sickle RBC as demonstrated by the partial inhibition of hypoxia-induced sickling in vitro. Our results suggest that liposomes can be used as sensitive probes for investigating changes in RBC membrane properties, especially those that affect intermembrane interactions, and that liposomal transport systems may have significant implications in the therapy of sickle cell disease.

Schwartz, Robert S.; Duzgunes, Nejat; Chiu, Danny Tsun-Yee; Lubin, Bertram

1983-01-01

318

Loading of gold nanoparticles inside the DPPC bilayers of liposome and their effects on membrane fluidities  

Microsoft Academic Search

Gold nanoparticles were loaded in the bilayer of dipalmitoylphosphatidylcholine (DPPC) liposomes, named as gold-loaded liposomes. Above the gel to liquid-crystalline phase transition temperature, membrane fluidities of DPPC liposomes were changed by loading the gold nanoparticles. Compared with liposomes without loading the gold nanoparticles, gold-loaded liposomes showed the lower fluorescence anisotropy values. That is, the membrane fluidities of DPPC bilayer were

Sung-Hee Park; Seong-Geun Oh; Ji-Young Mun; Sung-Sik Han

2006-01-01

319

FAST TRACK COMMUNICATION Tuning the spin state of iron phthalocyanine by ligand adsorption  

NASA Astrophysics Data System (ADS)

The future use of single-molecule magnets in applications will require the ability to control and manipulate the spin state and magnetization of the magnets by external means. There are different approaches to this control, one being the modification of the magnets by adsorption of small ligand molecules. In this paper we use iron phthalocyanine supported by an Au(111) surface as a model compound and demonstrate, using x-ray photoelectron spectroscopy and density functional theory, that the spin state of the molecule can be tuned to different values (S ~ 0, \\case {1}{2} , 1) by adsorption of ammonia, pyridine, carbon monoxide or nitric oxide on the iron ion. The interaction also leads to electronic decoupling of the iron phthalocyanine from the Au(111) support.

Isvoranu, C.; Wang, B.; Schulte, K.; Ataman, E.; Knudsen, J.; Andersen, J. N.; Bocquet, M. L.; Schnadt, J.

2010-12-01

320

Optical, morphological and structural characterization of Langmuir-Schaefer films of a functionalized copper phthalocyanine.  

PubMed

Langmuir-Schaefer (LS) films of copper(II) tetrakis-(isoprpoxy-carbonyl)-phthalocyanine (TiPCuPc) have been deposited onto various solid supports. Its floating film have been characterized at the air-water interface by means of Brewster Angle Microscopy and Langmuir curves. Vibrational modes of multilayer transferred LS film have been studied by Raman spectroscopy and the optical parameters (refractive index n and extinction coefficient k) have been determined in the visible range of the electromagnetic spectrum. Linearly polarized light absorbance measurements have been performed at room temperature in the 400-800 nm spectral range and the average orientation of the phthalocyanine rings have been estimated. Transmission electron microscopy has been also used to characterize the morphological properties of the LS film and a close packed arrangement of the deposited molecules has been observed. PMID:21794870

Giancane, Gabriele; Filippo, Emanuela; Manno, Daniela; Serra, Antonio; Valli, Ludovico

2011-06-30

321

Lactose substituted zinc phthalocyanine: a near infrared fluorescence imaging probe for liver cancer targeting.  

PubMed

A near infrared fluorescence probe, lactose substituted zinc phthalocyanine, [2,9(10),16(17),23(24)-tetrakis((1-(?-d-lactose-2-yl)-1H-1,2,3-triazol-4-yl)methoxyl)phthalocyaninato] zinc(II), was synthesized via click reaction. Structural characterization and optical experiment demonstrated its excellent biocompatibility and fluorescence imaging ability. Near infrared fluorescence imaging in vivo for liver cancer, lung cancer and melanoma cancer with tumor bearing nude mice as models demonstrated that lactose substituted zinc phthalocyanine has specifically targeting ability to liver cancer while no targeting to lung cancer or melanoma, which implied its potential in liver cancer diagnosis as a near infrared optical probe. PMID:23395663

Lv, Feng; He, Xujun; Wu, Li; Liu, Tianjun

2013-01-09

322

Acid-base properties and kinetic stability of tantalum phthalocyanine in proton-donor media  

SciTech Connect

The peculiarities of the electronic structure of elements of Groups IV and V and the high effectiveness of the charge on their atoms in coordination compounds may give important information on the character of the metal-ligand chemical bond in the chelate macrocyclic complexes of the phthalocyanine and porphyrin type with an extended ..pi.. structure. The authors investigated the acid-base properties of the meso-nitrogen atoms of the macroring of tantalum tetra-4-tert-butylphthalocyanine (OTaPC') in a mixture of anhydrous acetic and sulfuric acids, and also the kinetic stability of unsubstituted tantalum(IV) phthalocyanine OTaPc in the dissociation reaction in H/sub 2/SO/sub 4/.

Akopov, A.S.; Borovkov, N.Yu.

1986-10-10

323

Experimental and theoretical study of electronic structure of lutetium bi-phthalocyanine.  

PubMed

Using Near Edge X-Ray Absorption Fine Structure (NEXAFS) Spectroscopy, the thickness dependent formation of Lutetium Phthalocyanine (LuPc2) films on a stepped passivated Si(100)2×1 reconstructed surface was studied. Density functional theory (DFT) calculations were employed to gain detailed insights into the electronic structure. Photoelectron spectroscopy measurements have not revealed any noticeable interaction of LuPc2 with the H-passivated Si surface. The presented study can be considered to give a comprehensive description of the LuPc2 molecular electronic structure. The DFT calculations reveal the interaction of the two molecular rings with each other and with the metallic center forming new kinds of orbitals in between the phthalocyanine rings, which allows to better understand the experimentally obtained NEXAFS results. PMID:23802970

Bidermane, I; Lüder, J; Boudet, S; Zhang, T; Ahmadi, S; Grazioli, C; Bouvet, M; Rusz, J; Sanyal, B; Eriksson, O; Brena, B; Puglia, C; Witkowski, N

2013-06-21

324

Dimerization of titanyl phthalocyanine in thin films prepared by surface polymerization by ion-assisted deposition  

SciTech Connect

Surface polymerization by ion-assisted deposition (SPIAD), the simultaneous dosing of hyperthermal ions while depositing an organic oligomer, was used to deposit titanyl phthalocyanine (TiOPc) thin films with 50 and 100 eV acetylene ions. The properties of the SPIAD TiOPc thin films are compared with films of the evaporated TiOPc monomer via examination of the electronic structure, ultraviolet-visible absorbance, and composition. Mass spectrometry, x-ray photoelectron spectroscopy, and other methods were used to determine the film composition, chemical bonding, and to examine the electronic structure. These results showed the formation of TiOPc dimers bound face to face. However, the overall phthalocyanine ring structure otherwise remained intact, except for small amounts of atmospheric oxidation at ion-induced radical sites.

Zachary, Adam M.; Drabik, Martin; Choi, Yongsoo; Bolotin, Igor L.; Biederman, Hynek; Hanley, Luke [Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607-7061 (United States); Faculty of Mathematics and Physics, Department of Macromolecular Physics, Charles University, Prague (Czech Republic); Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607-7061 (United States); Faculty of Mathematics and Physics, Department of Macromolecular Physics, Charles University, Prague (Czech Republic); Department of Chemistry, University of Illinois at Chicago, Chicago, Illinois 60607-7061 (United States)

2008-03-15

325

Mechanism of Charge Transport in Cobalt and Iron Phthalocyanine Thin Films Grown by Molecular Beam Epitaxy  

SciTech Connect

Cobalt phthalocyanine (CoPc), iron phthalocyanine (FePc) and their composite (CoPc-FePc) films have been grown by molecular beam epitaxy (MBE). Grazing incidence X-ray diffraction (GIXRD) and scanning electron microscope (SEM) studies showed that composite films has better structural ordering compared to individual CoPc and FePc films. The temperature dependence of resistivity (in the temperature range 25 K- 100 K) showed that composite films are metallic, while individual CoPc and FePc films are in the critical regime of metal-to-insulator (M-I) transition The composite films show very high mobility of 110 cm{sup 2} V{sup -1} s{sup -1} at room temperature i.e. nearly two order of magnitude higher compared to pure CoPc and FePc films.

Kumar, Arvind; Samanta, Soumen; Singh, Ajay; Debnath, A. K.; Aswal, D. K.; Gupta, S. K. [Technical Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085 (India)

2011-12-12

326

Facile synthesis, self-assembly mechanism and field emission property of copper phthalocyanine nanowires  

NASA Astrophysics Data System (ADS)

Copper phthalocyanine (CuPc) nanowires were prepared through simple chemical route at room temperature. As-synthesized samples were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, Field emission scanning electron microscope. The self-assembly mechanism regarding the formation of copper phthalocyanine nanowires has also been presented here. Field emission of as prepared nanowires has been studied for a particular anode-sample spacing of 220 ?m. The chemically synthesized CuPc nanowires portray a good field emission property with turn-on field of 7.6 V/?m and field enhancement factor (?) of 1512, which might have promising application as a competitive cold cathode material in field emitting microelectronic devices.

Ghorai, U. K.; Saha, S.; Shee, S.; Chattopadhyay, K. K.

2013-06-01

327

Solvent-assisted growth of metal phthalocyanine thin films on Au(111)  

SciTech Connect

Thin films of metal phthalocyanine (MPc) are grown on an Au(111) support with a newly developed aerosol molecular beam deposition source and characterized in situ via ultrahigh vacuum scanning tunneling microscopy. MPcs are delivered to Au(111) in a series of N{sub 2}-entrained microsized solvent droplets of variable surface residence time. Phthalocyanine film registration to the herringbone reconstruction of the Au(111) surface, indicative of thermodynamically favored structure, is observed at submonolayer coverages for aromatic solvents with long residence times. Aerosol-deposited monolayer film structures are noncrystalline with tilted MPc orientations and vacancy nanocavities. Upon annealing, MPc molecules adopt flat-lying orientations with respect to the substrate and vacancies are eliminated. Film morphologies indicate solvation-mediated film nucleation and growth, with less long-range ordering that in vapor-generated films.

Tskipuri, Levan; Shao Qian; Reutt-Robey, Janice [Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742-4454 (United States)

2012-05-15

328

Electronic structure and current injection in zinc phthalocyanine doped with tetrafluorotetracyanoquinodimethane: Interface versus bulk effects  

Microsoft Academic Search

The p-type doping of zinc phthalocyanine (ZnPc) with the highly electronegative tetrafluorotetracyanoquinodimethane (F4-TCNQ) is investigated via direct and inverse photoemission spectroscopy and in situ current–voltage (I–V) measurement. The electron affinity of F4-TCNQ and the ionization energy of ZnPc are found to be energetically compatible with an electron transfer between the highest occupied molecular orbital (HOMO) of the host and the

Weiying Gao; Antoine Kahn

2002-01-01

329

Electrical properties of phthalocyanine based field effect transistors prepared on various gate oxides  

Microsoft Academic Search

We have investigated the electrical properties of top-contact type copper phthalocyanine (CuPc) based field effect transistors prepared on various high dielectric constant (high-K) gate oxide thin films, such as tantalum oxide (?r?20), tantalum oxide\\/silicon dioxide (?r?6), and aluminum oxide (?r?8) prepared by RF magnetron sputtering. A low operating voltage of less than 6 V and a field effect mobility ?CuPc

Teppei Higuchi; Tetsuro Murayama; Eiji Itoh; Keiichi Miyairi

2006-01-01

330

Singlet oxygen photogeneration efficiencies of a series of phthalocyanines in well-defined spectral regions  

Microsoft Academic Search

Singlet oxygen generation efficiencies of three photoactive metal phthalocyanines (Pcs of Al, Si, Zn) were investigated. This was achieved by monitoring the photooxidation of 4-chlorophenol (4-CP) in aquatic, aquatic\\/alcoholic or D2O environments with atmospheric oxygen and photons emitted in well-defined spectral regions. Another test was based on using the singlet oxygen chemical quencher 9,10-dimethylanthracene (DMA) in dimethylformamide. These tests were

P. Kluson; M. Drobek; A. Kalaji; S. Zarubova; J. Krysa; J. Rakusan

2008-01-01

331

Tumour visualization in a murine model by time-delayed fluorescence of sulphonated aluminium phthalocyanine  

Microsoft Academic Search

Mice bearing the MS-2 fibrosarcoma were administered 0.25, 0.5 or 1 mg kg-1 body weight (b.w.) of sulphonated aluminium phthalocyanine (AlS2Pc) (with average degree of sulphonation of 2.1), and time-gated fluorescence images were acquired up to 6 h after the injection.\\u000a Different excitation wavelengths (610, 650 and 670 nm) were tested. Red light excitation and 3 ns delayed detection allow

R. Cubeddu; G. Canti; P. Taroni; G. Valentini

1997-01-01

332

Optimization of the properties of bulk heterojunctions obtained by coevaporation of Zn-phthalocyanine\\/perylene  

Microsoft Academic Search

Zn-phthalocyanine (ZnPc)–perylene tetracarboxylic dianhydride (PTCDA) “bulk heterojunctions” has been obtained by vacuum evaporation from a single heated source. The composition, in weight, of the initial powder was 0, 10, 25, 50, 100% of PTCDA. The deposited films have been characterized by infrared, visible and near UV absorption, scanning electron microscopy and X-ray photoelectron spectroscopy (XPS). “Diodes bulk heterojunctions” ITO\\/ZnPc:PTCDA\\/Al and

H Derouiche; J. C Bernède; J L'Hyver

2004-01-01

333

Phthalocyanine-peptide conjugates via palladium-catalyzed cross-coupling reactions.  

PubMed

Phthalocyanines (Pc) were conjugated with peptide moieties to improve their target selectivity for potential use as fluorescence and/or positron emission tomography (PET) probes in medical imaging. Three synthetic methods based on palladium-catalyzed cross-coupling reactions (Sonogashira, Buchwald-Hartwig, and Suzuki-Miyaura) were investigated. Using these methods, a series of peptides monofunctionalized with Pc at the N/C-terminal position or on a phenylalanine side chain was obtained in good yields and characterized. PMID:21302913

Ali, Hasrat; Ait-Mohand, Samia; Gosselin, Simon; van Lier, Johan E; Guérin, Brigitte

2011-02-08

334

Zinc phthalocyanine-loaded PLGA biodegradable nanoparticles for photodynamic therapy in tumor-bearing mice  

Microsoft Academic Search

Nanoparticles formulated from the biodegradable copolymer poly(lactic-coglycolic acid) (PLGA) were investigated as a drug\\u000a delivery system to enhance tissue uptake, permeation, and targeting of zinc(II) phthalocyanine (ZnPc) for photodynamic therapy.\\u000a Three ZnPc nanoparticle formulations were prepared using a solvent emulsion evaporation method and the influence of sonication\\u000a time on nanoparticle shape, encapsulation and size distribution, in vitro release, and in

Maha Fadel; Kawser Kassab; Doa Abdel Fadeel

2010-01-01

335

Impedimetric and electrocatalytic properties of nanostructured iron(II) phthalocyanine at pyrolytic graphite electrode  

Microsoft Academic Search

The electron transfer behaviour of nanostructured iron(II) phthalocyanine (nanoFePc) at edge plane pyrolytic graphite electrodes (EPPGEs) has been investigated using cyclic voltammetry and electrochemical impedance spectroscopy (EIS). This study proves that the nanoFePc-based electrode exhibits faster heterogeneous electron transfer constant, kapp (about a magnitude higher) than the bulk FePc. In addition, the nanoFePc exhibited enhanced electrocatalytic properties towards the detection

Solomon A. Mamuru; Kenneth I. Ozoemena

2009-01-01

336

A novel glucose biosensor based on the nanoscaled cobalt phthalocyanine–glucose oxidase biocomposite  

Microsoft Academic Search

We report on the utilization of a novel nanoscaled cobalt phthalocyanine (NanoCoPc)–glucose oxidase (GOD) biocomposite colloid to create a highly responsive glucose biosensor. The biocomposite colloid is constructed under enzyme-friendly conditions by adsorbing GOD molecules on CoPc nanoparticles via electrostatic interactions. The glucose biosensor can be easily achieved by casting the biocomposite colloid on a pyrolytic graphite electrode (PGE) without

Kun Wang; Jing-Juan Xu; Hong-Yuan Chen

2005-01-01

337

High-resolution electron energy loss spectroscopy of chloroaluminum phthalocyanine ultrathin films  

Microsoft Academic Search

High-resolution electron energy loss spectra (HREELS) were measured for ultrathin films of chloroaluminum phthalocyanine (ClAlPc) deposited on a cleaved HOPG surface in order to investigate the molecular orientation and its thickness dependence. It was found that for the monolayer film ClAlPc molecules lie flat on the HOPG surface without heat treatment. With increase in the film thickness, the molecules become

Y. Azuma; T. Yokota; S. Kera; M. Aoki; K. K. Okudaira; Y. Harada; N. Ueno

1998-01-01

338

Penning ionization electron spectroscopy of titanyl phthalocyanine ultrathin films: electronic state and molecular orientation  

Microsoft Academic Search

Penning ionization electron spectroscopy (PIES) was used to investigate the molecular orientation, aggregation of molecules, and electronic structure of ultrathin films of titanyl phthalocyanine (OTiPc) vapor deposited on graphite and MoS2 substrates. For the monolayer film, the molecular orientation was remarkably different between the two substrates. At room temperature, molecules spread over and almost cover the substrate on graphite, whereas

S. Kera; A. Abduaini; M. Aoki; K. K. Okudaira; N. Ueno; Y. Harada; Y. Shirota; T. Tsuzuki

1998-01-01

339

Small molecule solar cells based on a series of water-soluble zinc phthalocyanine donors.  

PubMed

Organic solar cells based on a series of water-soluble zinc phthalocyanines (wsZnPc) with varying numbers of sulfonate peripheral substituents and a C60 donor have been fabricated and characterised. We find that the number of substituents affects both the V(oc) and J(sc) of the devices, with the disulfonated wsZnPc devices performing best. PMID:22433974

Ryan, James William; Anaya-Plaza, Eduardo; de la Escosura, Andrés; Torres, Tomas; Palomares, Emilio

2012-03-20

340

Dark conductivity in the x and alpha polymorphs of lithium phthalocyanine  

Microsoft Academic Search

This study focuses on the correlation existing between the structure and the continuous dark conductivity in single crystals, compacted powders and thin films of the lithium phthalocyanine radical (PcLi). The dc conductivity at room temperature measured in PcLi compacted powders is of about 2–4·10?5 (? cm)?1 for the x structure and 1–2·10?4 (? cm)?1 for the ? structure. The temperature

M. Brinkmann; C Chaumont; J.-J André

1998-01-01

341

Biodegradation of azo and phthalocyanine dyes by Trametes versicolor and Bjerkandera adusta  

Microsoft Academic Search

Eighteen fungal strains, known for their ability to degrade lignocellulosic material or lignin derivatives, were screened\\u000a for their potential to decolorize commercially used reactive textile dyes. Three azo dyes, Reactive Orange 96, Reactive Violet\\u000a 5 and Reactive Black 5, and two phthalocyanine dyes, Reactive Blue 15 and Reactive Blue 38, were chosen as representatives\\u000a of commercially used reactive dyes. From

A. Heinfling; M. Bergbauer; U. Szewzyk

1997-01-01

342

Organic field-effect transistors with high mobility based on copper phthalocyanine  

Microsoft Academic Search

Organic field-effect transistors that employ copper phthalocyanine (Cu–Pc) as the semiconducting layer can function as p-channel accumulation-mode devices. The charge carrier mobility of such devices is strongly dependent on the morphology of the semiconducting thin film. When the substrate temperature for deposition of Cu–Pc is 125 °C, a mobility of 0.02 cm2\\/V s and on\\/off ratio of 4×105 can be

Zhenan Bao; Andrew J. Lovinger; Ananth Dodabalapur

1996-01-01

343

Mössbauer study of oxygen adducts in solid Fe(II) phthalocyanines  

Microsoft Academic Search

Beta iron phthalocyanines (beta-FePc) oxygenated at low temperatures were investigated with the help of 57Fe Mössbauer spectroscopy and X-ray diffractometry (XRD). The oxygenation of FePc complex is the key step in the pyrolysis of the flat layered molecules that yields acicular iron carbide particles encaged in uniform carbon shells. Mössbauer spectroscopy revealed that upon oxygenation of beta-FePc new species were

E. Kuzmann; Z. Homonnay; A. Mylonakis; H. Yin; Y. Wei; K. Kovács; S. Kubuki; Z. Klencsár; A. Vértes; A. Nath

2010-01-01

344

Optical and photoelectric properties of manganese(II) phthalocyanine epoxy derivative  

Microsoft Academic Search

A novel soluble manganese(II) phthalocyanine (MnPc) epoxy derivative was synthesized and characterized by infrared (IR), electronic absorption spectrum and fluorescence spectrum. Fluorescence quantum yield of the derivative was measured in different solvents and reached 0.35 and 0.39 in dimethylsulfoxide (DMSO) and N, N-dimethylformamide (DMF), respectively. The derivative exhibits high solubility and excellent film-forming property. MnPc epoxy derivative can form cross-linked

Jinzhuan Zhu; Yue Shen; Feng Gu; Junchao Tao; Jiancheng Zhang

2007-01-01

345

Synthesis and photophysical studies of CdTe quantum dot-monosubstituted zinc phthalocyanine conjugates  

Microsoft Academic Search

The linkage of unsymmetrically monosubstituted 4-aminophenoxy zinc phthalocyanine (ZnAPPc, 5) to CdTe quantum dots capped with mercaptopropionic acid (MPA), l-cysteine (l-cys) or thioglycolic acid (TGA) has been achieved using the coupling agents ethyl-N(3-dimethylaminopropyl) carbodiimide and N-hydroxy succinimide, which facilitate formation of an amide bond to form the QD–ZnAPPc-linked conjugate. The formation of the amide bond was confirmed using Raman and

Sarah D’ Souza; Edith Antunes; Tebello Nyokong

2011-01-01

346

Efficacy of Liposomes and Hyperthermia in a Human Tumor Xenograft Model: Importance of Triggered Drug Release1  

Microsoft Academic Search

The tumor drug concentrations, drug distributions, and therapeutic efficacies achieved by three fundamentally different liposomes, nonther- mosensitive liposome (NTSL), traditional thermosensitive liposome (TTSL), and low temperature sensitive liposome (LTSL); free doxorubicin (DOX); and saline in combination with hyperthermia (HT) were directly compared in a human tumor xenograft model. NTSL is a nonthermosen- sitive liposome in the physiological temperature range, TTSL

Garheng Kong; Gopal Anyarambhatla; William P. Petros; Rod D. Braun; O. Michael Colvin; David Needham; Mark W. Dewhirst

2000-01-01

347

Nanoencapsulation of quercetin and resveratrol into elastic liposomes.  

PubMed

Based on the fact that quercetin (QUE) and resveratrol (RES) induce a synergic inhibition of the adipogenesis and increase apoptosis in adipocytes, and that sodium deoxycholate (SDC) has necrotic effects, the nanoencapsulation of QUE and RES into SDC-elastic liposomes is proposed as a new approach for dissolving the subcutaneous fat. The concentration of constituents and the effect of the drug incorporation into cyclodextrin inclusion complexes on the stability of QUE/RES-loaded liposomes were studied. The best liposomal formulation reduced the use of phosphatidylcholine and cholesterol in 17.7% and 68.4%, respectively. Liposomes presented a mean diameter of 149nm with a polydispersion index of 0.3. The zeta potential of liposomes was slightly negative (-13.3mV) due to the presence of SDC in the phospholipid bilayer. Encapsulation efficiency of QUE and RES into liposomes was almost 97%. To summarize, QUE/RES-loaded elastic liposomes are stable and suitable for subcutaneous injection, thereby providing a new strategy for reducing subcutaneous fat. PMID:23103506

Cadena, Pabyton G; Pereira, Marcela A; Cordeiro, Rafaela B S; Cavalcanti, Isabella M F; Barros Neto, Benício; Pimentel, Maria do Carmo C B; Lima Filho, José Luiz; Silva, Valdinete L; Santos-Magalhães, Nereide S

2012-10-25

348

Optical delivery of liposome encapsulated chemical stimuli to neuronal cells  

NASA Astrophysics Data System (ADS)

Spatially confined and precise time delivery of neuroactive molecules is an important issue in neurophysiology. In this work we developed a technique for delivering chemical stimuli to cultured neurons consisting in encapsulating the molecules of interest in liposomes. These vectors were then loaded in reservoirs consisting of glass capillaries. The reservoirs were placed in the recording chamber and single liposomes were trapped and transported out by optical tweezers to the site of stimulation on cultured neurons. Finally, the release of liposome content was induced by application of UV-pulses, breaking the liposome membrane. The efficiency of encapsulation and release were first evaluated by loading the liposomes with fluorescein. In order to test the effect of the UV-induced release, liposomes with diameter ranging from 1 to 10 ?m (fL to pL volumes), were filled with KCl and tested on neuronal cells. Neuronal cultures, loaded with Ca2+ dye, were monitored by imaging intracellular Ca2+. An efficient release from the liposomes was demonstrated by detectable calcium signals, indicating stimulated depolarization of the neuronal cells by KCl. The present technique represents an alternative method for focal chemical stimulation of cultured cells that circumvents some of the limitations of microejection and photorelease of caged compounds.

Pinato, Giulietta; Raffaelli, Tiziano; D'Este, Elisa; Tavano, Federica; Cojoc, Dan

2011-09-01

349

Elastic liposomes mediated transcutaneous immunization against Hepatitis B.  

PubMed

Transcutaneous immunization presents a major challenge due to poor permeability of antigens through the skin barrier. To overcome this limitation ultradeformable lipid vesicles, the elastic liposomes, could be a better module for transcutaneous delivery of these proteinaceous antigens. In the present investigation Hepatitis B surface antigen (HBsAg)-loaded elastic liposomes were utilized as a mode for enhanced immunity against the antigen. Elastic liposomes were prepared by conventional rotary evaporation method and characterized for various parameters such as vesicles shape and surface morphology, size and size distribution, entrapment efficiency, elasticity, turbidity, stability and in vitro release pattern. Ex vivo cellular uptake and fluorescence studies were also conducted. In vivo studies were performed by measuring the immune response elicited by topically applied HBsAg-loaded elastic liposomes and compared to the intramuscularly administered alum-adsorbed HBsAg solution, topically applied plain HBsAg solution and physical mixture of HBsAg and elastic liposomes. Results indicate that transcutaneous immunization via elastic liposomes induces robust systemic and mucosal antibody response against HBsAg as compared to other formulations. The fluorescence microscopy results suggest prominent skin permeation and biodistribution, demonstrating efficient delivery of antigens to the immunocompetent Langerhans cells (LC) and lymphatics. The elastic liposomal formulation provides higher entrapment efficiency, enhanced penetration and effective immunoadjuvant property justifying its potential for improved vaccine delivery. PMID:16600441

Mishra, Dinesh; Dubey, Vaibhav; Asthana, Abhay; Saraf, D K; Jain, N K

2006-03-15

350

PEGylated elastic liposomal formulation for lymphatic targeting of zidovudine.  

PubMed

The present study was aimed at in vitro and in vivo evaluation of PEGylated elastic liposomal formulation for lymphatic targeting of zidovudine (AZT). PEGylated elastic liposomal formulation was prepared and characterized for characteristic in vitro, ex-vivo and in vivo parameters. The plain and PEGylated elastic liposomal formulation showed transdermal flux of 99.8+/-5.8 and 119.5+/-5.2 microg/cm(2)/hr, respectively across the rat skin. Results of biodistribution study indicated 27-fold higher accumulation of AZT in lymphoid tissues after application of PEGylated elastic liposomes as compared to free drug. The efficient localization of elastic liposomal formulation in lymphatic system is of particular interest for HIV therapy, taking in account that replication of HIV mainly takes place in the lymphoid system. The Cellular uptake studies showed significantly higher cellular uptake in lymphoid cells (MT-2 cell line) from PEGylated elastic liposomal formulation (88.9+/-8.7%) in comparison to phosphate buffer saline (PBS, pH 7.4) solution of drug (27.1+/-2.8%). The entrapment of AZT into PEGylated elastic liposomes represents a potential approach for overcoming the toxicity by its selective uptake in lymphoid organs. This represents attractive approach for sustained and targeted delivery of AZT. PMID:18855596

Jain, Subheet; Tiwary, A K; Jain, N K

2008-10-01

351

Inhalation treatment of pulmonary fibrosis by liposomal prostaglandin E2.  

PubMed

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, and often fatal form of interstitial lung disease. We hypothesized that the local pulmonary delivery of prostaglandin E2 (PGE2) by liposomes can be used for the effective treatment of IPF. To test this hypothesis, we used a murine model of bleomycin-induced IPF to evaluate liposomal delivery of PGE2 topically to the lungs. Animal survival, body weight, hydroxyproline content in the lungs, lung histology, mRNA, and protein expression were studied. After inhalation delivery, liposomes accumulated predominately in the lungs. In contrast, intravenous administration led to the accumulation of liposomes mainly in kidney, liver, and spleen. Liposomal PGE2 prevented the disturbances in the expression of many genes associated with the development of IPF, substantially restricted inflammation and fibrotic injury in the lung tissues, prevented decrease in body weight, limited hydroxyproline accumulation in the lungs, and virtually eliminated mortality of animals after intratracheal instillation of bleomycin. In summary, our data provide evidence that pulmonary fibrosis can be effectively treated by the inhalation administration of liposomal form of PGE2 into the lungs. The results of the present investigations make the liposomal form of PGE2 an attractive drug for the effective inhalation treatment of idiopathic pulmonary fibrosis. PMID:23228437

Ivanova, Vera; Garbuzenko, Olga B; Reuhl, Kenneth R; Reimer, David C; Pozharov, Vitaly P; Minko, Tamara

2012-12-08

352

Liposome micropatterning based on laser-induced forward transfer  

NASA Astrophysics Data System (ADS)

The numerous properties of liposomes, i.e., nontoxicity, biodegradability, and their ability to encapsulate different biological active substances in aqueous and lipid phase, make them perfect models of biomembranes. Liposomes made up of phospholipids may be used to study new applications such as cell targeting or, under specific experimental conditions, may be applied in micro and nano-sized biosensors. This study demonstrates the capability of direct laser printing of liposomes in micron-scale patterns for the realization of biosensors or drug delivery systems. The transfer experiments were carried out onto ordinary glass substrates, and optical microscopy images reveal that well-defined patterns without splashes can be obtained for a narrow range of laser transfer fluences using 193 nm irradiation and an intermediate triazene polymer. The triazene polymer with different thicknesses was used as sacrificial layer with the purpose of protecting the liposome solution from direct laser irradiation. It was found that the thickness of the sacrificial layer should exceed 150 nm to obtain clean, debris-free patterns. Moreover, the integrity of the liposomes after laser transfer was maintained as demonstrated through fluorescence microscopy. Raman spectroscopy data suggest that the chemical composition of the liposomes does not change for transfer fluences in the range of 40 to 60 mJ/cm2. Following these results, one can envision that liposome patterns obtained by LIFT can be ultimately applied for in vitro and in vivo studies.

Palla-Papavlu, Alexandra; Paraico, Iurie; Shaw-Stewart, James; Dinca, Valentina; Savopol, Tudor; Kovacs, Eugenia; Lippert, Thomas; Wokaun, Alexander; Dinescu, Maria

2011-03-01

353

The effect of intercalants on the host liposome.  

PubMed

When phospholipids are vigorously dispersed in water, liposomes are formed. In the present study, we have explored the effect of intercalant concentration on various properties of unilamellar liposomes. Liposomes were sonically intercalated with vitamin E acetate (VitEAc) and hypericin (Hy) until no difference in light transmission was observed, which reflects the formation of liposomes of minimal diameter. Our studies indicate that the intercalant structure and concentration have an influence on the liposome diameter, which could be directly measured by cryogenic transmittance electronic microscopy. Thus, intercalated VitEAc substantially decreased the diameter of unilamellar dimyristoylphosphatidylcholine liposomes, whereas Hy did not. In addition, we followed peak intensities in the absorbance and fluorescence spectra of Hy as a function of intercalant concentration in the liposomal solution. Initially, the fluorescence intensity increased linearly with concentration; however, the curve then arched asymptotically, followed by a decrease in fluorescence at yet higher concentrations. Because the Hy monomer is the only species that emits fluorescence, we believe that the decrease of fluorescence intensity is the result of Hy aggregation. PMID:22799604

Cohen, Yael; Weitman, Hana; Afri, Michal; Yanus, Rinat; Rudnick, Safra; Talmon, Yeshayahu; Schmidt, Judith; Aped, Pinchas; Shatz, Smadar; Ehrenberg, Benjamin; Frimer, Aryeh A

2012-07-16

354

A voyage into the synthesis and photophysics of homo- and heterobinuclear ensembles of phthalocyanines and porphyrins.  

PubMed

The remarkable properties of both phthalocyanines and porphyrins as individual building blocks have motivated the synthesis and study of homo- and heterobinuclear conjugates as light-harvesting systems. These planar chromophores share important electronic features such as high molar absorption coefficients, rich redox chemistry and interesting photoinduced energy and/or electron transfer abilities. In addition, some of these properties can be tuned by the introduction of different peripheral substituents and metal centres. In this review, we present relevant synthetic strategies for the preparation of covalent and supramolecular, homo- and heterobinuclear systems based on phthalocyanine and porphyrin chromophores, leading to a variety of architectures. In such systems, the degree of electronic interaction between the components is highly dependent on the electronic features of the two macrocycles, their linkage, and the molecular topology of the ensemble. In addition, incorporation of electroactive units into these binuclear systems has been pursued, affording multicomponent, donor-acceptor conjugates. In-depth photophysical characterization of the ground- and excited-state features of many of these homo- and heterobinuclear phthalocyanine and/or porphyrin ensembles has also been presented. Particular attention has been paid to understand the fundamental dynamics of the energy transfer and charge separation processes of these systems. This review intends to offer a general overview of the preparation of this class of compounds and the study of their photophysical properties which clearly show their potentiality as model compounds of light-harvesting complexes. PMID:23832123

de la Torre, Gema; Bottari, Giovanni; Sekita, Michael; Hausmann, Anita; Guldi, Dirk M; Torres, Tomás

2013-09-23

355

Inhomogeneous charge transfer within monolayer zinc phthalocyanine absorbed on TiO2(110).  

PubMed

The d-orbital contribution from the transition metal centers of phthalocyanine brings difficulties to understand the role of the organic ligands and their molecular frontier orbitals when it adsorbs on oxide surfaces. Here we use zinc phthalocyanine (ZnPc)/TiO(2)(110) as a model system where the zinc d-orbitals are located deep below the organic orbitals leaving room for a detailed study of the interaction between the organic ligand and the substrate. A charge depletion from the highest occupied molecular orbital is observed, and a consequent shift of N1s and C1s to higher binding energy in photoelectron spectroscopy (PES). A detailed comparison of peak shifts in PES and near-edge X-ray absorption fine structure spectroscopy illustrates a slightly uneven charge distribution within the molecular plane and an inhomogeneous charge transfer screening between the center and periphery of the organic ligand: faster in the periphery and slower at the center, which is different from other metal phthalocyanine, e.g., FePc/TiO(2). Our results indicate that the metal center can substantially influence the electronic properties of the organic ligand at the interface by introducing an additional charge transfer channel to the inner molecular part. PMID:22519339

Yu, Shun; Ahmadi, Sareh; Sun, Chenghua; Adibi, Pooya Tabib Zadeh; Chow, Winnie; Pietzsch, Annette; Göthelid, Mats

2012-04-21

356

Photodynamic effect of different aluminum and zinc phthalocyanines on isolated nerve cell  

NASA Astrophysics Data System (ADS)

The photodynamic effects of sulphonated zinc (ZnPcS2, ZnPcS3 and ZnPcS4) and aluminum (AlPcS3) phthalocyanines as well as phosphonated aluminum phthalocyanine on the firing of isolated crayfish mechanoreceptor neurons were studied. After 30 min photosensitization neurons were irradiated with He-Ne laser (632.8 nm, 0.3 W/cm2) and changes in neuron firing frequency were recorded. Neuron firing was found to be very sensitive to photodynamic impact and served as a sensitive indicator of cell photodamage. The dynamics of the neuron responses to photodynamic effects included stages of firing activation and/or inhibition prior to irreversible firing abolition and depended on the photosensitizer type and concentration. The comparison of the dependencies of neuron lifetime on photosensitizer concentrations showed that the most effective photosensitizer was ZnPcS2. High photodynamic efficiencies of phthalocyanines was related with the weak dependence of photodynamic effect on sensitizer concentration indicating to the initiation about 3 secondary chain processes such as free radical membrane damage caused by photon absorption by one photosensitizer molecule.

Uzdensky, Anatoly B.; Zhavoronkova, Anna A.; Dergacheva, Olga Y.; Derkacheva, V. M.

1999-12-01

357

Distorted fused porphyrin-phthalocyanine conjugates: synthesis and photophysics of supramolecular assembled systems with a pyridylfullerene.  

PubMed

In the current work, we report on the synthesis and photophysical features of supramolecular hybrid systems that are based on newly fused porphyrin-phthalocyanine (P-Pc) conjugates and a pyridylfullerene. The ZnP-ZnPc conjugate was synthesized in three steps starting with a Diels-Alder reaction between ?-vinylporphyrin and fumaronitrile. The resulting mixture of isomeric adducts was then dehydrogenated to yield the corresponding benzo[b]porphyrin-2(1),2(2)-dicarbonitrile. In the final step, cyclotetramerization with 4-tert-butylphthalonitrile, in the presence of zinc acetate, afforded the bis-metalated conjugate. Selective demetallation of ZnP led to the H(2)P-ZnPc conjugate. For both conjugates steric hindrance is the inception to a bent configuration, which does, however, not preclude enlargement of the ?-conjugated system, that is, the porphyrins and the phthalocyanines. The two conjugates coordinate N-(4-pyridyl)fullero[c]pyrrolidine giving rise to the corresponding supramolecular porphyrin-phthalocyanine-fullerene systems. Photophysical measurements corroborate a sequential deactivation in the excited state, namely an initial intramolecular energy transfer from ZnP or H(2)P to ZnPc followed by an intramolecular charge transfer to yield ZnP-(ZnPc)?(+)-(C(60))?(-) and H(2)P-(ZnPc)?(+)-(C(60))?(-), respectively. PMID:21614392

Pereira, Ana M V M; Soares, Ana R M; Hausmann, Anita; Neves, Maria G P M S; Tomé, Augusto C; Silva, Artur M S; Cavaleiro, José A S; Guldi, Dirk M; Torres, Tomás

2011-05-26

358

Aqueous Speciation and Electrochemical Properties of a Water-Soluble Manganese Phthalocyanine Complex#  

PubMed Central

The speciation behavior of a water-soluble manganese(III) tetrasulfonated phthalocyanine complex was investigated with UV-visible and electron paramagnetic resonance (EPR) spectroscopies, as well as cyclic voltammetry. Parallel-mode EPR (in dimethylformamide:pyridine solvent mix) reveals a six-line hyperfine signal, centered at a g-value of 8.8, for the manganese(III) monomer, characteristic of the d4 S=2 system. The color of an aqueous solution containing the complex is dependent upon the pH of the solution; the phthalocyanine complex can exist as a water-bound monomer, a hydroxide-bound monomer, or an oxo-bridged dimer. Addition of coordinating bases such as borate or pyridine changes the speciation behavior by coordinating the manganese center. From the UV-visible spectra, complete speciation diagrams are plotted by global analysis of the pH-dependent UV-visible spectra, and a complete set of pKa values is obtained by fitting the data to a standard pKa model. Electrochemical studies reveal a pH-independent quasi-reversible oxidation event for the monomeric species, which likely involves oxidation of the organic ligand to the radical cation species. Adsorption of the phthalocyanine complex on the carbon working electrode was sometimes observed. The pKa values and electrochemistry data are discussed in the context of the development of mononuclear water-oxidation catalysts.

Blakemore, James D.; Hull, Jonathan F.

2012-01-01

359

Preparation, magnetic and electromagnetic properties of organic magnetic prepolymer containing copper phthalocyanine ring  

NASA Astrophysics Data System (ADS)

A novel kind of organic magnetic prepolymer containing copper phthalocyanine ring was prepared via the polymerization of ferrocenyl organic metal magnetic resin (FOMR) with cuprous chloride. The process of prepolymerization was monitored by Fourier transform infrared spectroscopy and ultraviolet-visible spectrophotometry. Magnetic behavior of the samples was studied by a vibrating sample magnetometer.The experimental results indicated that the organic magnetic prepolymer containing copper phthalocyanine ring showed ferromagnetic property and the magnetism of the samples can be finely tuned by controlling the condition of the reaction. The maximum saturation magnetization of the organic magnetic prepolymer containing copper phthalocyanine ring increased from 3.69 to 8.38 emu/g by increasing the reaction time. Meanwhile, the remnant magnetization increased from 1.06 to 2.36 emu/g. Measurement of electromagnetic parameters of the samples showed that complex permittivity and complex permeability also increased with increase in the reaction time. Among these, the imaginary part of permittivity increased from 0.22 to 0.38 at the frequency of 10.0 GHz.

Wei, Junji; Xu, Mingzhen; Zhang, Jiandong; Zhao, Rui; Liu, Xiaobo

2012-09-01

360

Photodynamic effects of 31 different phthalocyanines on a human keratinocyte cell line.  

PubMed

Phthalocyanines (Pcs, colored macromolecular compounds with the ability to generate singlet oxygen) represent a promising group of photosensitizers due to their intense absorption in the red and UV portion of the spectrum which leads to their excitation. In order to characterize possible toxic effects associated with eventual practical use and application of these chemicals, we employed an in vitro cell culture model to evaluate cytotoxic effects of 31 different phthalocyanines using neutral red uptake assay. An immortalized human keratinocyte cell line HaCaT was exposed to the tested chemicals for 2 or 24h, either with or without illumination in the last 60min of the exposure period. After 2- or 24-h exposure without illumination, no cytotoxic effects or weak cytotoxic effects were induced by any Pc under the study and EC50 values could not be obtained within the tested concentration ranges (1.25-20mgL(-1) or 0.625-10mgL(-1)). On the other hand, exposure to phthalocyanines under illumination induced a significant cytotoxic effect. The most pronounced cytotoxicity was elicited by Pcs previously shown to have high positive charge densities at peripheral parts of substituent groups, which is most likely the factor responsible for the binding of Pc to negatively charged membranes on the cell surface and thus guaranteeing the tight connection necessary for the singlet oxygen attack on the cell surface. PMID:23790830

Jan?ula, Daniel; Maršálek, Blahoslav; Babica, Pavel

2013-06-20

361

In vitro photodynamic effect by phthalocyanine in A549 cell line  

NASA Astrophysics Data System (ADS)

Photodynamic therapy (PDT) utilizes a combination of sensitizer, visible light and molecular oxygen to generate singlet oxygen and reactive oxygen species (ROS) such as hydrogen peroxide, hydroxyl radical and superoxid anion. Photochemical reactions lead to damage and destruction of cancer cells. The most suitable and effective source of radiation used in PDT is a laser. For this study, a semiconductor laser with output power of 50 mW and 675 nm was selected. In this paper we report a generation of ROS using chloroaluminium disulphonated phthalocyanine (ClAlPcS2) in A549 bronchogenic carcinoma cell line after PDT in vitro. Phthalocyanines, belonging to a new generation of substances for PDT, exhibit effective tissue penetration because of their proper light absorption region, chemical stability and photodynamic stability. The fluorescence measurement with molecular probes, CM-H2DCFDA and Amplex Red, was performed for detection of ROS generation and hydrogen peroxide release from cells. Our results demonstrated, that irradiation of cells by laser dose of 10 J.cm-2 induces higher rates of fluorescence in cells loaded with phthalocyanine compared to 20 J.cm-2. Furthermore, the production of ROS increases up to sensitizer concentration of 10 ?M. The highest ROS generation was observed at laser dose of 10 J.cm-2 and 10 ?M ClAlPcS2. The rates of fluorescence for hydrogen peroxid measurements were almost identical with all chosen concentrations at laser doses of 10 and 20 J.cm-2.

Nevrelova, Pavla; Kolarova, Hana; Bajgar, Robert; Strnad, Miroslav

2007-03-01

362

Controlling Morphology and Molecular Packing of Alkane Substituted Phthalocyanine Blend Bulk Heterojunction Solar Cells.  

PubMed

Systematic changes in the exocyclic substiution of core phthalocyanine platform tune the absorption properties to yield commercially viable dyes that function as the primary light absorbers in organic bulk heterojunction solar cells. Blends of these complementary phthalocyanines absorb a broader portion of the solar spectrum compared to a single dye, thereby increasing solar cell performance. We correlate grazing incidence small angle x-ray scattering structural data with solar cell performance to elucidate the role of nanomorphology of active layers composed of blends of phthalocyanines and a fullerene derivative. A highly reproducible device architecture is used to assure accuracy and is relevant to films for solar windows in urban settings. We demonstrate that the number and structure of the exocyclic motifs dictate phase formation, hierarchical organization, and nanostructure, thus can be employed to tailor active layer morphology to enhance exciton dissociation and charge collection efficiencies in the photovoltaic devices. These studies reveal that disordered films make better solar cells, short alkanes increase the optical density of the active layer, and branched alkanes inhibit unproductive homogeneous molecular alignment. PMID:23589766

Jurow, Matthew J; Hageman, Brian A; Dimasi, Elaine; Nam, Chang-Yong; Pabon, Cesar; Black, Charles T; Drain, Charles Michael

2013-02-01

363

Liposomal daunorubicin as treatment for Kaposi's sarcoma  

PubMed Central

Anthracycline compounds including daunorubicin are the foundation of many modern chemotherapeutic regimens. However, the side-effects of these compounds can be severe, leading to alopecia, nausea, immune deficiency, and cardiotoxicity. For immunocompromised patients with aggressive Kaposi’s sarcoma (KS), these complications often preclude the completion of appropriate chemotherapeutic regimens. This review focuses on the development and efficacy of liposomal daunorubicin (DaunoXome®; DNX) carriers for the treatment of KS. Encouragingly, DNX demonstrated increased in vivo stability and specificity. As a result, KS patients benefit from higher cumulative chemotherapeutic doses without significant cardiotoxicity. Tumor response to DNX treatment surpasses that of non-encapsulated daunorubicin and is similar to that observed with conventional multi-drug therapies such as ABV (doxorubicin, bleomycin, vincristine). Moreover, some reports indicate the patient quality of life during therapy may improve with DNX treatment. Although the development of DNX represents a significant advance in KS therapy, recent data suggest that additional modification of the liposomal carrier to include pegylation or target specific antibodies may further increase daunorubicin efficacy in the future.

Petre, Christin E; Dittmer, Dirk P

2007-01-01

364

The Safety of Liposome Bupivacaine, A Novel Local Analgesic Formulation.  

PubMed

OBJECTIVE:: Pooled safety data from 10 randomized, double-blind studies of liposome bupivacaine, a novel local analgesic formulation, were examined. METHODS:: Eight hundred twenty-three patients received liposome bupivacaine (dose, 66 to 532 mg) given locally at the surgical site in 5 different settings (hemorrhoidectomy, bunionectomy, breast augmentation, total knee arthroplasty, and hernia repair); 446 received bupivacaine HCl (dose, 75 to 200 mg) and 190 received placebo. Adverse events (AEs) were monitored for up to 36 days after administration. RESULTS:: Overall, 48% of patients were men and 21% were 65 years and older. Incidence of AEs was 62% for patients receiving liposome bupivacaine, versus 75% and 43% for patients receiving bupivacaine HCl and placebo, respectively. The most common AEs (incidence >10%) in the liposome bupivacaine arms were nausea, constipation, and vomiting. One death was reported in the liposome bupivacaine group and 1 in the bupivacaine HCl group; both deemed unrelated to study drug. Serious AEs were reported in 2.7% of patients receiving liposome bupivacaine, versus 5.4% and 1.1% of those receiving bupivacaine HCl and placebo, respectively. In both the liposome bupivacaine and bupivacaine HCl groups, 6% of patients experienced a cardiac AE; these were primarily tachycardia (4% vs. 5%, respectively) and bradycardia (2% vs. 1%, respectively). Overall incidence of treatment-related cardiac AEs was <1%; all were associated with liposome bupivacaine. All of these events were assessed by investigators as possibly related to study drug; all were mild or moderate in severity, and none required therapeutic intervention. DISCUSSION:: Liposome bupivacaine exhibited acceptable tolerability across 823 patient exposures. PMID:23446090

Viscusi, Eugene R; Sinatra, Raymond; Onel, Erol; Ramamoorthy, Sonia L

2013-02-26

365

Enhanced transdermal delivery of acyclovir sodium via elastic liposomes.  

PubMed

The elastic liposomes bearing acyclovir sodium were prepared for its enhanced transdermal delivery by conventional rotary evaporation method and characterized for various parameters such as vesicle shape and surface morphology, size and size distribution, entrapment efficiency, elasticity, polydispersity index, turbidity and in vitro release pattern. Permeability studies of acyclovir sodium incorporated in elastic liposomes were performed across artificial membranes and rat skin. Skin permeation potential of the developed formulation was assessed using confocal laser scanning microscopy, that revealed an enhanced permeation of the formulation to the deeper layers of the skin (up to 160 microm) following channel like pathways. Skin permeation profile of elastic liposomal formulation bearing acyclovir sodium was observed and the investigations revealed an enhanced transdermal flux (6.21 +/- 1.8 microg/cm(2)/hr) and decreased lag time (0.6 hr) for acyclovir sodium. The obtained flux was nearly 2.0 and 6.3 times higher than conventional liposomal formulation bearing acyclovir sodium and plain drug solution, respectively (p < 0.01). The elastic liposomal formulation for transdermal delivery of acyclovir sodium provides better transdermal flux, higher entrapment efficiency, ability as a self-penetration enhancer and effectiveness for transdermal delivery as compared with conventional liposomes. In vivo studies showed that on transdermal application of elastic liposomes, the concentration of acyclovir sodium in plasma was found to be 105 +/- 9.4 ng/ml after 24 hr which is about 4.2 times compared with conventional liposomes. Thus it is concluded that the elastic liposomes may be promising vehicles for the transdermal delivery of acyclovir sodium. PMID:18379926

Jain, Sanjay K; Gupta, Yashwant; Jain, Anekant; Rai, Kavita

366

Liposomes and skin: from drug delivery to model membranes.  

PubMed

The early eighties saw the introduction of liposomes as skin drug delivery systems, initially promoted primarily for localised effects with minimal systemic delivery. Subsequently, a novel ultradeformable vesicular system (termed "Transfersomes" by the inventors) was reported for transdermal delivery with an efficiency similar to subcutaneous injection. Further research illustrated that the mechanisms of liposome action depended on the application regime and the vesicle composition and morphology. Ethical, health and supply problems with human skin have encouraged researchers to use skin models. Traditional models involved polymer membranes and animal tissue, but whilst of value for release studies, such models are not always good mimics for the complex human skin barrier, particularly with respect to the stratum corneal intercellular lipid domains. These lipids have a multiply bilayered organization, a composition and organization somewhat similar to liposomes. Consequently researchers have used vesicles as skin model membranes. Early work first employed phospholipid liposomes and tested their interactions with skin penetration enhancers, typically using thermal analysis and spectroscopic analyses. Another approach probed how incorporation of compounds into liposomes led to the loss of entrapped markers, analogous to "fluidization" of stratum corneum lipids on treatment with a penetration enhancer. Subsequently scientists employed liposomes formulated with skin lipids in these types of studies. Following a brief description of the nature of the skin barrier to transdermal drug delivery and the use of liposomes in drug delivery through skin, this article critically reviews the relevance of using different types of vesicles as a model for human skin in permeation enhancement studies, concentrating primarily on liposomes after briefly surveying older models. The validity of different types of liposome is considered and traditional skin models are compared to vesicular model membranes for their precision and accuracy as skin membrane mimics. PMID:18572392

El Maghraby, G M; Barry, B W; Williams, A C

2008-05-08

367

Development of a platform of antibody-presenting liposomes.  

PubMed

Antibody-presenting liposomes present high interest as drug delivery systems. The association of antibodies to liposomes is usually realized by covalent coupling of IgGs or their antigen-binding fragments to lipid polar head groups by means of hetero-bifunctional crosslinkers. We present here an original platform of IgG-presenting liposomes which is based on a fusion protein between Annexin-A5 (Anx5) and the IgG-binding ZZ repeat derived from Staphylococcus aureus protein A. The Anx5ZZ fusion protein acts as a bi-functional adaptor that anchors IgGs to liposomes in a non covalent and highly versatile manner. The interactions between IgGs, Anx5ZZ and liposomes were characterized by PAGE, dynamic light scattering and fluorescence quenching assays, establishing that binding of Anx5ZZ to IgGs and of Anx5ZZ-IgG complexes to liposomes is complete with stoichiometric amounts of each species. We found that the sequence of assembly is important and that Anx5ZZ-IgG complexes need to be formed first in solution and then adsorbed to liposomes in order to avoid aggregation. The targeting capacity of Anx5ZZ-IgG-functionalized liposomes was demonstrated by electron microscopy on an ex vivo model system of atherosclerotic plaques. This study shows that the Anx5ZZ adaptor constitutes an efficient platform for functionalizing liposomes with IgGs. This platform may present potential applications in molecular imaging and drug delivery. PMID:22589054

Garnier, Boris; Tan, Sisareuth; Gounou, Céline; Brisson, Alain R; Laroche-Traineau, Jeanny; Jacobin-Valat, Marie-Josée; Clofent-Sanchez, Gisèle

2012-02-09

368

Giant liposome preparation for imaging and patch-clamp electrophysiology.  

PubMed

The reconstitution of ion channels into chemically defined lipid membranes for electrophysiological recording has been a powerful technique to identify and explore the function of these important proteins. However, classical preparations, such as planar bilayers, limit the manipulations and experiments that can be performed on the reconstituted channel and its membrane environment. The more cell-like structure of giant liposomes permits traditional patch-clamp experiments without sacrificing control of the lipid environment. Electroformation is an efficient mean to produce giant liposomes >10 ?m in diameter which relies on the application of alternating voltage to a thin, ordered lipid film deposited on an electrode surface. However, since the classical protocol calls for the lipids to be deposited from organic solvents, it is not compatible with less robust membrane proteins like ion channels and must be modified. Recently, protocols have been developed to electroform giant liposomes from partially dehydrated small liposomes, which we have adapted to protein-containing liposomes in our laboratory. We present here the background, equipment, techniques, and pitfalls of electroformation of giant liposomes from small liposome dispersions. We begin with the classic protocol, which should be mastered first before attempting the more challenging protocols that follow. We demonstrate the process of controlled partial dehydration of small liposomes using vapor equilibrium with saturated salt solutions. Finally, we demonstrate the process of electroformation itself. We will describe simple, inexpensive equipment that can be made in-house to produce high-quality liposomes, and describe visual inspection of the preparation at each stage to ensure the best results. PMID:23851612

Collins, Marcus D; Gordon, Sharona E

2013-06-21

369

Improved stability of liposome in oil\\/water emulsion by association of amphiphilic polymer with liposome and its effect on bioactive skin permeation  

Microsoft Academic Search

In this study, we demonstrated that the stability of phosphatidylcholine (PC)-cholesterol (Chol) liposomes can be improved in oil in water (o\\/w) emulsion by association of amphiphilic polyelectrolyte, poly(methacrylic acid-co-stearyl methacrylate) with PC–Chol liposomes. Differential scanning calorimetry and photocorrelation spectroscopy results showed that the polymer-associated liposomes were more stable than the PC–Chol liposomes when mixed with the o\\/w emulsion. This difference

Eun Chul Cho; Hyung Jun Lim; Jongwon Shim; Junoh Kim; Ih-Seop Chang

2007-01-01

370

Growth of phthalocyanine doped and undoped nanotubes using mild synthesis conditions for development of novel oxygen reduction catalysts.  

PubMed

Precious metal alloys have been the predominant electrocatalyst used for oxygen reduction in fuel cells since the 1960s. Although performance of these catalysts is high, they do have drawbacks. The two main problems with precious metal alloys are catalyst passivation and cost. This is why new novel catalysts are being developed and employed for oxygen reduction. This paper details the low temperature solvothermal synthesis and characterization of carbon nanotubes that have been doped with both iron and cobalt centered phthalocyanine. The synthesis is a novel low-temperature, supercritical solvent synthesis that reduces halocarbons to form a metal chloride byproduct and carbon nanotubes. Perchlorinated phthalocyanine was added to the nanotube synthesis to incorporate the phthalocyanine structure into the graphene sheets of the nanotubes to produce doped nanotubes that have the catalytic oxygen reduction capabilities of the metallo-phthalocyanine and the advantageous material qualities of carbon nanotubes. The cobalt phthalocyanine doped carbon nanotubes showed a half wave oxygen reduction potential of -0.050 ± 0.005 V vs Hg\\HgO, in comparison to platinum's half wave oxygen reduction potential of -0.197 ± 0.002 V vs Hg\\HgO. PMID:21043456

Arechederra, Robert L; Artyushkova, Kateryna; Atanassov, Plamen; Minteer, Shelley D

2010-11-02

371

Cholesterol Derivatives Based Charged Liposomes for Doxorubicin Delivery: Preparation, In Vitro and In Vivo Characterization  

PubMed Central

Cholesterol plays a critical role in liposome composition. It has great impact on the behavior of liposome in vitro and in vivo. In order to verify the possible effects from cholesterol charge, surface shielding and chemical nature, two catalogs of liposomes with charged and PEGylated cholesterols were synthesized. Anionic liposomes (AL) and cationic liposomes (CL) were prepared, with charges from hemisuccinate and lysine in cholesterol derivatives, respectively. Characteristics of different formulated liposomes were investigated after doxorubicin encapsulation, using neutral liposomes (NL) as control. Results showed that after PEGylation, AL and CL liposomes displayed prolonged retention release profile, while kept similar size distribution, encapsulation efficiency, low cytotoxicity and hemolysis comparing with NL. Confocal laser scanning microscopy and flow cytometry experiments confirmed the significantly higher cell uptake from AL and CL vesicles than the NL in mouse breast carcinoma and melanoma cells, human epithelial carcinoma and hepatoma cells. It was in accordance with our corresponding cellular mortality studies of DOX-loaded liposomes. The in vivo anti-tumor effect experiments from charged liposomes also presented much higher tumor inhibition effect (70% vs 45%, p < 0.05) than NL liposomes. This is the first time reporting anti-cancer effect from charged cholesterol liposome with/without PEGylation. It may give deeper understanding on the liposome formulation which is critical for liposome associated drug research and development.

Nie, Yu; Ji, Li; Ding, Hong; Xie, Li; Li, Li; He, Bin; Wu, Yao; Gu, Zhongwei

2012-01-01

372

Ethanol treatment a Non-extrusion method for asymmetric liposome size optimization  

PubMed Central

Background siRNA is a new tool for treatment of diseases such as cancer. However, it cannot be used directly due to rapid degradation in body fluid and blood stream; therefore, vectors are necessary for protection of siRNA against RNases and also for its precise delivery to the target cells. Since viral vector causes cancer and immune response in the host, liposomes are more preferable vectors. Liposome size is an important factor for longer circulation time. Extrusion minimizes the liposome size; however, it leads to less liposome encapsulation. Moreover, it changes structure of asymmetric liposomes. Findings Here, ethanol treatment is introduced as a method of liposome size optimization that significantly decreases the liposome size without any effect on liposome encapsulation and its asymmetric structure formulation. For this, after liposome formation while there is some ether in solution, ethanol was added to fresh liposomes (25 and 30 percent of total liposomes volume) and liposomes were incubated at room temperature with mild agitation for 20 minutes. Finally, the extra ethanol and ether were removed by dialysis. Conclusion Utilizing this method the liposome size was successfully decreased about 100 nm. The size of optimized liposomes (200 nm) is quite suitable for in vivo target delivery.

2013-01-01

373

Oxidation level-dependent zwitterionic liposome adsorption and rupture by graphene-based materials and light-induced content release.  

PubMed

Liposomes may be stably adsorbed or ruptured on graphene-based materials, depending on the oxidation state of graphene. IR-induced liposome leakage is achieved, since graphene oxide does not induce liposome leakage spontaneously. PMID:23239613

Ip, Alexander C-F; Liu, Biwu; Huang, Po-Jung Jimmy; Liu, Juewen

2012-12-13

374

[Development of ultrasonic cancer therapy using ultrasound sensitive liposome].  

PubMed

Ultrasound (US) has been utilized as a useful tool for diagnosis and therapy. US mediated drug and gene delivery is paid to attention as a non-invasive system. The combination of US and microbubbles generated microjet stream by inducing disruption of bubbles and resulted in enhancing permeability of cell membrane. This phenomenon has been utilized as driving force for drug and gene delivery. Recently, we developed ultrasound sensitive liposome [Bubble liposome (BL)] containing perfluoropropane gas. US combined with BL could effectively transfer gene in vivo compared to conventional cationic liposomes. Using this method, we succeeded to obtain a therapeutic effect in cancer gene therapy with Interleukin-12 corded plasmid DNA. Therefore, it is expected that US combined with BL might be a useful non-viral vector system. From this result, the fusion of liposomal and ultrasound technologies would be important for establishment of advanced cancer therapy. PMID:21139393

Suzuki, Ryo; Oda, Yusuke; Utoguchi, Naoki; Maruyama, Kazuo

2010-12-01

375

Liposomal delivery of boron to tumors for BNCT  

SciTech Connect

Results are reported on the use of liposomes to encapsulate boron containing compounds for use as a delivery vehicle to tumors. An increase in injected dose to the tumor in mammary glands of mice was realized.

Hawthorne, M.F.; Feakes, D.A.; Shelly, K. [Univ. of California, Los Angeles, CA (United States)

1994-12-31

376

[Liposomal boron delivery system for neutron capture therapy].  

PubMed

Boron neutron capture therapy (BNCT) is a binary cancer treatment based on the nuclear reaction of two essentially nontoxic species, (10)B and thermal neutrons. High accumulation and selective delivery of boron into tumor tissue are the most important requirements to achieve efficient neutron capture therapy of cancers. This review focuses on the liposomal boron delivery system (BDS) as a recent promising approach that meets these requirements for BNCT. BDS involves two strategies: (1) encapsulation of boron in the aqueous core of liposomes and (2) accumulation of boron in the liposomal bilayer. Various boronated liposomes have been developed and significant boron accumulation into tumor tissue with high tumor/blood boron ratios has been achieved by BDS. PMID:18239367

Nakamura, Hiroyuki

2008-02-01

377

[Immunosuppressive effect of cyclosporin A incapsulated into liposomes].  

PubMed

A preparation of cyclosporine A (CsA) in small liposomes (300 nm) was tested in a rat model of heterotopic cardiac allograft. At a daily dose of 1,5 mg/kg during 14 days, the graft survival rate was 30.4 +/- 2.8 days with a liposome-CsA solution versus 16 +/- 2.3 days with a Cremophore-CsA solution (p less than 0.01). Animals treated with the liposome-CsA preparation exhibited less weight loss than animals treated with cremophore-CsA solution (p less than 0.01). It is likely that the up-take of CsA by macrophages, when incapsulated into liposomes is dramatically enhanced; these cells have been pointed out at targets for IL2 inhibition by CsA. PMID:2129987

Arnoux, R; Dufourcq, J; Smeesters, C; Lalanne, J; Deminière, C; Penin, E; Clerc, M; Poteaux, L; Dartigues, J F; Michel, A

1990-01-01

378

Liposomal Packaging Generates Wnt Protein with In Vivo Biological Activity  

PubMed Central

Wnt signals exercise strong cell-biological and regenerative effects of considerable therapeutic value. There are, however, no specific Wnt agonists and no method for in vivo delivery of purified Wnt proteins. Wnts contain lipid adducts that are required for activity and we exploited this lipophilicity by packaging purified Wnt3a protein into lipid vesicles. Rather than being encapsulated, Wnts are tethered to the liposomal surface, where they enhance and sustain Wnt signaling in vitro. Molecules that effectively antagonize soluble Wnt3a protein but are ineffective against the Wnt3a signal presented by a cell in a paracrine or autocrine manner are also unable to block liposomal Wnt3a activity, suggesting that liposomal packaging mimics the biological state of active Wnts. When delivered subcutaneously, Wnt3a liposomes induce hair follicle neogenesis, demonstrating their robust biological activity in a regenerative context.

Zhao, Ludan; Kim, Jae-Beom; ten Berge, Derk; Ponnusamy, Karthik; Carre, A. Lyonel; Dudek, Henryk; Zachlederova, Marie; McElhaney, Michael; Brunton, Shirley; Gunzner, Janet; Callow, Marinella; Polakis, Paul; Costa, Mike; Zhang, Xiaoyan M.; Helms, Jill A.; Nusse, Roel

2008-01-01

379

Avoiding failed reconstitution of ultradeformable liposomes upon dehydration.  

PubMed

Although freeze-drying is an ordinarily used technique to dehydrate conventional liposomes, we have found that ultradeformable liposomes (UDLs) suffered irreversible aggregation when rehydrated upon freeze-drying (99.4% water elimination), even in high sugar content (4/1 sucrose/lipid mass ratio). When dehydrated by speed vac and vacuum drying, two alternative techniques that rendered less pronounced dehydration (94.27 and 96.2% water elimination, respectively) and avoid ice formation, however, UDL could only be successfully rehydrated when vacuum dried in 4/1 sucrose/lipid mass ratios. Conventional liposomes, on the other hand, were successfully reconstituted upon dehydrated by the three methods in lower sugar content (2/1 sucrose/lipid mass ratio). These results indicated that the 27% mole sodium cholate within the UDL lipid matrix was responsible for a greater and differential mechanical sensitivity of the bilayers to the different dehydration stress, as compared to conventional liposomes. PMID:19429279

Montanari, J; Roncaglia, D I; Lado, L A; Morilla, M J; Romero, E L

2009-01-21

380

Infrared spectra of phthalocyanine and naphthalocyanine in sandwich-type (na)phthalocyaninato and porphyrinato rare earth complexes. Part 3. The effects of substituents and molecular symmetry on the infrared characteristics of phthalocyanine in bis(phthalocyaninato) rare earth complexes  

Microsoft Academic Search

The infra-red (IR) spectroscopic data for a series of 45 homoleptic unsubstituted and substituted bis(phthalocyaninato) rare earth complexes M(Pc)2 and M(Pc*)2 [M=Y, La…Lu except Pm; H2Pc=phthalocyanine; H2Pc*=2,3,9,10,16,17,24,25-octakis(octyloxy)phthalocyanine (H2OOPc) and 2(3),9(10),16(17),24(25)-tetra(tert-butyl)phthalocyanine (H2TBPc)] have been collected with resolution of 2 cm?1. The IR spectra for M(Pc)2 and M(OOPc)2 are much simpler than those of M(TBPc)2, revealing the relatively higher symmetry of the

Fanli Lu; Meng Bao; Changqin Ma; Xianxi Zhang; Dennis P. Arnold; Jianzhuang Jiang

2003-01-01

381

Plant annexin form homodimer during Ca(2+)-dependent liposome aggregation.  

PubMed

The annexin (p35) was isolated from the fruits of green pepper (Capsicum annum). The partial amino acid sequence of p35 was analyzed. p35 had an endonexin fold as annexin consensus sequences. Purified p35 had other annexin like characters such as strongly bind to phosphatidylserine and phosphatidylinositol, phospholipase A2 inhibition and liposome aggregation. The zero-length crosslinking assay revealed that p35 formed a homodimer during Ca(2+)-dependent liposome aggregation. PMID:7627125

Hoshino, T; Mizutani, A; Chida, M; Hidaka, H; Mizutani, J

1995-04-01

382

[Preparation and properties of folate receptor-targeted cationic liposomes].  

PubMed

A cationic liposome was prepared with a ligand directed at folate receptor in cancer cells to improve selectivity and facilitate its access to the cancer cells. Folate-polyethyleneglycol-distearoylphosphatidylethanolamine (F-PEG-DSPE) was synthesized by reacting folic acid (F), polyoxyethylene-bis-amine (NH2-PEG-NH2), succinic anhydride (SUC) with distearoylphosphatidylethanolamine (DSPE). Folate receptor-targeted liposomes composed of DPPC/DC-Chol/F-PEG-DSPE (10:10:0.75, molar ratio) were prepared by film dispersion method. A negative charged dextran fluorescein anionic (DFA) was used as a model to explore the in vitro properties and cell uptake efficiencies of liposomal DFA on KB and HpeG2 cells. The formulations were investigated by orthogonal experiment using encapsulation efficiency as the optimized indexes. The size, 4 potential, entrapment efficiency and DFA release in vitro were investigated. The results showed that DFA loaded folate receptor-targeted liposomes had high encapsulation efficiency and the mean size approximately 144 nm. The cationic liposomes had some toxicity to HepG2 cells, and at low concentration (0.0125-0.1 micromol x L(-1)) , the toxicity was linear with the concentration of DC-chol. The folate receptor-targeted liposomes showed great effects on increasing liposome cellular uptake of DFA. In summary, the method of film dispersion method is suitable for producing DFA loaded lipsomes with high entrapment efficiency, small size and slow release. The folate receptor-targeted liposomes can efficiently deliver DFA into cells in vitro. This may represent a promising option for researches on cancer gene therapy. PMID:19239034

Yan, Ying; Qi, Xian-Rong

2008-11-01

383

Marine lipid-based liposomes increase in vivo FA bioavailability  

Microsoft Academic Search

Liposomes made from an extract of natural marine lipids and containing a high n-3 PUFA lipid ratio were envisaged as oral\\u000a route vectors for FA supplements in order to increase PUFA bioavailability. The absorption of FA in thoracic lymph duct-cannulated\\u000a rats, after intragastric feeding of dietary fats in the form of liposomes or fish oil, was compared. Lipid and FA

Maud Cansell; Fabienne Nacka; Nicole Combe

2003-01-01

384

Liposome-mediated gene transfer to lung isografts  

Microsoft Academic Search

Objectives: Our objectives were to determine the feasibility, efficacy, and safety of in vivo and ex vivo liposome-mediated gene transfer to lung isografts.Methods: Fischer rats were divided into three main groups: (1) Nontransplant setting: Liposome–chloramphenicol acetyl transferase cDNA was intravenously injected, and lungs were harvested at different time points: 2, 6, 12, and 24 hours; 2, 5, 8, and 21

Carlos H. R. Boasquevisque; Teng C. Lee; Bassem N. Mora; David Peterson; William O. Osburn; Matthew Bernstein; Wei Zhang; Jennifer B. Nietupski; Ronald K. Scheule; Joel D. Cooper; Mitchell D. Botney; G. Alexander Patterson

1997-01-01

385

Technology of Liposomal Tiosens, Cifelin and Lysomustin for Industrial Purposes  

NASA Astrophysics Data System (ADS)

This work is devoted to the development of national antineoplastic drug (Tiosens, Cifelin, Lysomustin) liposomal dosage form (LDF) circuit technology and their manufacturing technology. In modern oncology liposomes, which are hollow phospholipid vesicles, are used as delivery systems protected drugs from biodegradation, and healthy cells from the toxic effect of chemotherapeutic agents. The technology of their production is stretching and multistage. It is also necessary to give consideration a lot of factors that influence on the finished product quality.

Sanarova, E. V.; Kotova, E. A.; Lantsova, A. V.

2012-02-01

386

Photosensitive liposomes as potential drug delivery vehicles for photodynamic therapy  

NASA Astrophysics Data System (ADS)

Light-sensitive liposomes incorporating a photochromic phospholipid (Bis-Azo PC) have been developed which exhibit light-activated release of entrapped contents and intervesicular fusion. The trapping and light-induced release of inorganic ions, fluorescent market dyes, and the antitumor drug methotrexate have been demonstrated. These results are discussed together with some of the potential therapeutic applications of light-sensitive liposomes.

Morgan, Christopher G.; Mitchell, A. C.; Chowdhary, R. K.

1991-11-01

387

Quantitative Immunoblot Assay for Assessment of Liposomal Antibody Conjugation Efficiency  

Microsoft Academic Search

Routine direct assessment of immunoglobulin (Ig)–liposome(lp) conjugation efficiency has been impeded by phospholipid interference with standard protein and immunoassay methods. Rabbit IgG conjugated to anionic liposomes was quantitated in immunoblots using computer image analysis techniques. Lp-coupled Ig was separated from free Ig by dialysis in disposable Spectra\\/Por units (MWCO 300 kDa). Differential Lowry protein assay (DLA) of the thiolated Ig

Melvin E. Klegerman; Andrew J. Hamilton; Shao-Ling Huang; Susan D. Tiukinhoy; Amer A. Khan; Robert C. MacDonald; David D. McPherson

2002-01-01

388

Solubilization of Liposomes by Weak Electrolyte Drugs. I. Propranolol  

Microsoft Academic Search

The solubilization of dimyristoylphosphatidylcholine (DMPC) liposomes by a weak electrolyte drug, propranolol (PPL) hydrochloride, has been studied as a function of pH, [PPL], [DMPC], and temperature. The solubilization of liposomes at 40°C by 0.2 mM PPL occurred at different rates from 2.9 to 14.4 mM DMPC but converged at complete solubilization after 13 hr at pH 12.0. At the same

James A. Rogers; Gurupadappa V. Betageri; Young W. Choi

1990-01-01

389

In-situ transmission electron microscopy of liposomes in an aqueous environment.  

PubMed

The characterization of liposomes was undertaken using in-situ microfluidic transmission electron microscopy. Liposomes were imaged without contrast enhancement staining or cryogenic treatment, allowing for the observation of functional liposomes in an aqueous environment. The stability and quality of the liposome structures observed were found to be highly dependent on the surface and liposome chemistries within the liquid cell. The successful imaging of liposomes suggests the potential for the extension of in-situ microfluidic TEM to a wide variety of other biological and soft matter systems and processes. PMID:23886420

Hoppe, Sarah M; Sasaki, Darryl Y; Kinghorn, Aubrianna N; Hattar, Khalid

2013-07-31

390

Ultrasonic Activation of Thermally Sensitive Liposomes  

NASA Astrophysics Data System (ADS)

Cancerous cells are known to be more vulnerable to mild hyperthermia than healthy cells, which can survive temperatures above 43° C for brief periods of time. Currently in phase III clinical trials for liver cancer, ThermoDox® (Celsion Corporation) is a drug delivery system containing doxorubicin, a common anti-cancer agent, encapsulated within a thermally sensitive liposome designed to release its contents above 39.5° C. Activation of such an agent with the use of HIFU, which can generate localized heating non-invasively, would combine the benefits of targeted chemotherapy and hyperthermia while minimizing undesirable systemic side-effects. To that end, the resolution and reliability with which HIFU-induced hyperthermia can achieve Thermodox® release was investigated using a novel agar-based gel embedding liposomes at clinically relevant concentrations (0.02 mg/ml). The gel was exposed to 1.15 MHz HIFU (Sonic Concepts H102) using a range of clinically relevant pressure amplitudes (0-6 MPa peak rarefactional), duty cycles (10-100%) and exposure durations to identify optimal insonation conditions for complete doxorubicin release. The corresponding temperature profiles were mapped with 0.5 mm spatial resolution using an embedded needle thermocouple; drug release was quantified using fluorimetry. Complete release over the HIFU focal area was obtained for 6-s continuous wave exposure at 5.2 MPa peak rarefactional pressure, i.e. under exposure conditions for which the temperature exceeded 43° C throughout the focal volume. For a given HIFU energy input, both the final temperature reached and the rate of heating were found to affect release significantly. However, ThermoDox® release was achieved only due to thermal effects of HIFU, and not by other ultrasound effects, such as cavitation without heating, showing robustness of HIFU-induced hyperthermia as a release mechanism.

Mylonopouloua, Eleonora; Arvanitisa, Costas D.; Bazan-Peregrinoa, Miriam; Arora, Manish; Coussios, Constantin C.

2010-03-01

391

Development and characterization of multilamellar liposomes containing pyridostigmine.  

PubMed

Abstract Pyridostigmine has cardioprotective activity in both free and liposomal forms. This study aimed to develop and characterize liposomal formulations of pyridostigmine. For this, a spectrophotometric ultraviolet (UV) analytical method, at 270?nm, was developed and validated to quantify liposomal pyridostigmine. The method was linear in ranges from 0.02 to 0.09?mg/mL. The accuracy of this method was determined intra- and inter-day; the results of coefficient of variation were of 1.73-2.72% and 0.32-2.32%, respectively. The accuracy ranged between 99.45% and 101.12%. The method has not changed by influence of liposomal matrix and demonstrated being able to quantify pyridostigmine in liposomes. Two liposomal multilamellar formulations were developed: a constituted by dystearoyl-phosphatidylcholine (DSPC) and cholesterol (CHOL) other by dioleil-phosphatidylcholine (DOPC) and CHOL. The encapsulation efficiency was determined as 23.4% and 15.4%, respectively. Analyses of size and release of pyridostigmine from the formulations were made and the results showed that the formulations are viable for future studies in vivo. PMID:23682846

Souza, Ana Carolina Moreira; Grabe-Guimarães, Andrea; Souza, Jacqueline; Botacim, Wallace Entringer; Almeida, Tamara Marine; Frézard, Fréderic Jean Georges; Silva Barcellos, Neila Márcia

2013-05-17

392

Polydopamine/liposome coatings and their interaction with myoblast cells.  

PubMed

Surface-mediated drug delivery is a recent concept, where active surface coatings are employed to deliver therapeutic cargo to cells. Herein, we explore the potential of liposomes embedded in polydopamine (PDA) coatings to serve as drug deposits stored on planar substrates. We quantify the PDA growth rate on glass by XPS and show that PDA coatings support myoblast adherence and proliferation. Further, PDA capping layers were deposited on glass substrates precoated with poly(L-lysine) and zwitterionic liposomes. Already thin PDA capping layers render liposome coated surfaces cell adhesive. We experimentally show for the first time, the internalization of a model hydrophobic cargo, that is, fluorescent lipids embedded within the lipid bilayer of liposomes by the cells from the surface. This is evident from the fluorescence exhibited by the cells grown on PDA coatings containing fluorescently labeled liposomes, with the highest fluorescent intensity found in the close proximity of the cell nuclei. The cargo uptake efficiency depends on the thickness of the PDA capping layer and the cell residence time on the coated substrates. Taken together, we demonstrate the first step toward the establishment of a versatile approach using liposomal drug deposits in polymer thin films for surface-mediated drug delivery. PMID:21539399

Lynge, Martin E; Ogaki, Ryosuke; Laursen, Anja Overgård; Lovmand, Jette; Sutherland, Duncan S; Städler, Brigitte

2011-05-17

393

Liposomes in drug delivery: a patent review (2007 - present).  

PubMed

Introduction: Drug therapy is frequently limited by the widespread biodistribution of the active agents and the little specificity for non-healthy cells. Therefore, inadequate drug concentrations result into the site of action, and severe toxicity may also arise. To address the problem, liposome-based medicines have tried to improve pharmacotherapy. Areas covered: The review provides an updated revision of the lately published patents covering recent advances in liposome-based drug delivery. They are principally related to the control of drug biodistribution by using stealth, stimuli-sensitive and/or liposomal structures surface modified for ligand-mediated delivery. The contribution further highlights liposome-based theranosis. Expert opinion: Liposomes have received great attention given their biocompatibility, biodegradability and targetability. From 2007 to present date, patent publications related to their use in drug delivery have shown the move towards more stable structures with optimized drug delivery capabilities, further combining passive and active targeting concepts to gain control of the in vivo fate. However, the introduction of all these liposomal structures in the disease arena is still a challenge. Two key aspects are the difficulty of identifying easy and economic synthesis conditions which can be scaled up in the pharmaceutical industry, and the need for complementary investigations illustrating risks of toxicity/immunogenicity. PMID:23957267

Arias, José L

2013-08-19

394

Double charge inversion in polyethylenimine-decorated liposomes.  

PubMed

The study of the interaction of a cationic polymer as PEI with phospholipids membranes is of special relevance for gene therapy because the PEI is a potential nonviral vector to transfer DNA in living cells. We used light scattering, zeta potential, and electron transmission microscopy to characterize the interaction between DMPG and DOPC liposomes with PEI as a function of the charge molar ratio, pH, temperature, initial size of the liposomes, and headgroup of the lipids. Unexpectedly, a double charge inversion and two different ranges of PEI-liposome concentrations where an aggregation occurs were found, when the proper pH and initial size of the liposomes were chosen. The interaction is analyzed in terms of the interaction potential proposed by Velegol and Thwar for colloidal particles with a nonuniform surface charge distribution. Results show a remarkable dependence of the stability on pH and the initial size of the liposomes, which explains the low reproducibility of the experiments if no special care is taken in preparing the samples. Comparatively small changes in the pH or in the liposomes size lead to a completely different stability behavior. PMID:22712613

Sabín, Juan; Vázquez-Vázquez, Carmen; Prieto, Gerardo; Bordi, Federico; Sarmiento, Félix

2012-07-03

395

Efficacy of incorporating cyclosporine into liposomes to reduce its nephrotoxicity.  

PubMed

A preparation of cyclosporine (CsA) in liposomes was tested in the rat to evaluate its effectiveness in reducing CsA nephrotoxicity. The drug was injected intravenously in unilaterally nephrectomized Lewis rats at a daily dose of 25 mg/kg for 14 days, either in a cremophore solution (eight rats) or in a preparation of liposomes (eight rats). Another group of four animals received the cremophore solution alone. Overall, rats treated with the CsA-liposome preparation had reduced toxicity, exhibiting better survival rates and less weight loss than those treated with the CsA-cremophore. Incorporating CsA into liposomes induced a statistically significant (p less than 0.05) reduction in the otherwise progressive increase of serum creatinine during week 2 of the experiment. Following administration of CsA-liposome preparation, epithelial cells of the proximal renal tubules appeared morphologically normal, without evidence of vacuolization, which is characteristic of CsA nephrotoxicity and was seen in the CsA-cremophore group. Although the exact mechanism is not clearly understood, it is likely that the tissue distribution of CsA, when incorporated into liposomes, is modified in favour of the reticuloendothelial cells, thereby sparing highly sensitive, but non-target organs such as the kidneys. PMID:3257403

Smeesters, C; Giroux, L; Vinet, B; Arnoux, R; Chaland, P; Corman, J; St-Louis, G; Daloze, P

1988-01-01

396

The Antimicrobial Activity of Liposomal Lauric Acids Against Propionibacterium acnes  

PubMed Central

This study evaluated the antimicrobial activity of lauric acid (LA) and its liposomal derivatives against Propionibacterium acnes (P. acnes), the bacterium that promotes inflammatory acne. First, the antimicrobial study of three free fatty acids (lauric acid, palmitic acid and oleic acid) demonstrated that LA gives the strongest bactericidal activity against P. acnes. However, a setback of using LA as a potential treatment for inflammatory acne is its poor water solubility. Then the LA was incorporated into a liposome formulation to aid its delivery to P. acnes. It's demonstrated that the antimicrobial activity of LA was not only well maintained in its liposomal derivatives but also enhanced at low LA concentration. In addition, the antimicrobial activity of LA-loaded liposomes (LipoLA) mainly depended on the LA loading concentration per single liposomes. Further study found that the LipoLA could fuse with the membranes of P. acnes and release the carried LA directly into the bacterial membranes, thereby killing the bacteria effectively. Since LA is a natural compound that is the main acid in coconut oil and also resides in human breast milk and liposomes have been successfully and widely applied as a drug delivery vehicle in the clinic, the LipoLA developed in this work holds great potential of becoming an innate, safe and effective therapeutic medication for acne vulgaris and other P. acnes associated diseases.

Yang, Darren; Pornpattananangkul, Dissaya; Nakatsuji, Teruaki; Chan, Michael; Carson, Dennis; Huang, Chun-Ming; Zhang, Liangfang

2009-01-01

397

Phthalocyanine-aggregated polymeric nanoparticles as tumor-homing near-infrared absorbers for photothermal therapy of cancer.  

PubMed

Phthalocyanine-aggregated Pluronic nanoparticles were constructed as a novel type of near-infrared (NIR) absorber for photothermal therapy. Tiny nanoparticles (~ 60 nm, FPc NPs) were prepared by aqueous dispersion of phthalocyanine-aggregated self-assembled nanodomains that were phase-separated from the melt mixture with Pluronic. Under NIR laser irradiation, FPc NPs manifested robust heat generation capability, superior to an individual cyanine dye and cyanine-aggregated nanoparticles. Micro- and macroscopic imaging experiments showed that FPc NPs are capable of internalization into live cancer cells as well as tumor accumulation when intravenously administered into living mice. It is shown here that continuous NIR irradiation of the tumor-targeted FPc NPs can cause phototherapeutic effects in vitro and in vivo through excessive local heating, demonstrating potential of phthalocyanine-aggregated nanoparticles as an all-organic NIR nanoabsorber for hyperthermia. PMID:23082099

Lim, Chang-Keun; Shin, Jiyoung; Lee, Yong-Deok; Kim, Jungahn; Oh, Keun Sang; Yuk, Soon Hong; Jeong, Seo Young; Kwon, Ick Chan; Kim, Sehoon

2012-09-20

398

Physicochemical properties of Mg-phthalocyanine molecules covalently bonded to the surface of nanopores in a silicate gel matrix  

NASA Astrophysics Data System (ADS)

Molecules of Mg-tetracarboxyphthalocyanine, chemically modified with 3-aminopropyltrimethoxysilane, were immobilized on the surface of the nanopores in a silicate gel matrix by copolymerizing them with tetraethoxysilane monomer. Formation of covalent bonds between the Mg-phthalocyanine molecules and the surface of the nanopores in the silicate xerogel was confirmed by the absence of leaching of the “grafted” pigment from the interior volume of the xerogel to the liquid extraction agent, and also by IR Fourier spectroscopy data. The observed bleaching of the activated silicate xerogel under normal atmospheric conditions is reversible: subsequent heat treatment restores the original absorption spectrum. We hypothesize that two mechanisms are responsible for the observed effect: formation of high order associates of the Mg-phthalocyanine molecules involving water molecules adsorbed from the atmosphere, and/or oxidation of the phthalocyanine macrocycle with disruption of the conjugation chain.

Arabei, S. M.; Pavich, T. A.

2007-09-01

399

Phthalocyanine-Aggregated Polymeric Nanoparticles as Tumor-Homing Near-Infrared Absorbers for Photothermal Therapy of Cancer  

PubMed Central

Phthalocyanine-aggregated Pluronic nanoparticles were constructed as a novel type of near-infrared (NIR) absorber for photothermal therapy. Tiny nanoparticles (~ 60 nm, FPc NPs) were prepared by aqueous dispersion of phthalocyanine-aggregated self-assembled nanodomains that were phase-separated from the melt mixture with Pluronic. Under NIR laser irradiation, FPc NPs manifested robust heat generation capability, superior to an individual cyanine dye and cyanine-aggregated nanoparticles. Micro- and macroscopic imaging experiments showed that FPc NPs are capable of internalization into live cancer cells as well as tumor accumulation when intravenously administered into living mice. It is shown here that continuous NIR irradiation of the tumor-targeted FPc NPs can cause phototherapeutic effects in vitro and in vivo through excessive local heating, demonstrating potential of phthalocyanine-aggregated nanoparticles as an all-organic NIR nanoabsorber for hyperthermia.

Lim, Chang-Keun; Shin, Jiyoung; Lee, Yong-Deok; Kim, Jungahn; Oh, Keun Sang; Yuk, Soon Hong; Jeong, Seo Young; Kwon, Ick Chan; Kim, Sehoon

2012-01-01

400

Tuning the stability of graphene layers by phthalocyanine-based oPPV oligomers towards photo- and redoxactive materials.  

PubMed

In contrast to pristine zinc phthalocyanine (1), zinc phthalocyanine based oPPV-oligomers (2-4) of different chain lengths interact tightly and reversibly with graphite, affording stable and finely dispersed suspensions of mono- to few-layer graphene-nanographene (NG)-that are photoactive. The p-type character of the oPPV backbones and the increasing length of the oPPV backbones facilitate the overall ?-? interactions with the graphene layers. In NG/2, NG/3, and NG/4 hybrids, strong electronic coupling between the individual components gives rise to charge transfer from the photoexcited zinc phthalocyanines to NG to form hundreds of picoseconds lived charge transfer states. The resulting features, namely photo- and redoxactivity, serve as incentives to construct and to test novel solar cells. Solar cells made out of NG/4 feature stable and repeatable photocurrent generation during several 'on-off' cycles of illumination with monochromatic IPCE values of around 1%. PMID:23418045

Brinkhaus, Linda; Katsukis, Georgios; Malig, Jenny; Costa, Rubén D; Garcia-Iglesias, Miguel; Vázquez, Purificación; Torres, Tomás; Guldi, Dirk M

2013-02-18

401

Stealth liposomes: review of the basic science, rationale, and clinical applications, existing and potential  

PubMed Central

Among several promising new drug-delivery systems, liposomes represent an advanced technology to deliver active molecules to the site of action, and at present several formulations are in clinical use. Research on liposome technology has progressed from conventional vesicles (“first-generation liposomes”) to “second-generation liposomes”, in which long-circulating liposomes are obtained by modulating the lipid composition, size, and charge of the vesicle. Liposomes with modified surfaces have also been developed using several molecules, such as glycolipids or sialic acid. A significant step in the development of long-circulating liposomes came with inclusion of the synthetic polymer poly-(ethylene glycol) (PEG) in liposome composition. The presence of PEG on the surface of the liposomal carrier has been shown to extend blood-circulation time while reducing mononuclear phagocyte system uptake (stealth liposomes). This technology has resulted in a large number of liposome formulations encapsulating active molecules, with high target efficiency and activity. Further, by synthetic modification of the terminal PEG molecule, stealth liposomes can be actively targeted with monoclonal antibodies or ligands. This review focuses on stealth technology and summarizes pre-clinical and clinical data relating to the principal liposome formulations; it also discusses emerging trends of this promising technology.

Immordino, Maria Laura; Dosio, Franco; Cattel, Luigi

2006-01-01

402

Antibody-Hapten Recognition at the Surface of Functionalized Liposomes Studied by SPR: Steric Hindrance of Pegylated Phospholipids in Stealth Liposomes Prepared for Targeted Radionuclide Delivery  

PubMed Central

Targeted PEGylated liposomes could increase the amount of drugs or radionuclides delivered to tumor cells. They show favorable stability and pharmacokinetics, but steric hindrance of the PEG chains can block the binding of the targeting moiety. Here, specific interactions between an antihapten antibody (clone 734, specific for the DTPA-indium complex) and DTPA-indium-tagged liposomes were characterized by surface plasmon resonance (SPR). Non-PEGylated liposomes fused on CM5 chips whereas PEGylated liposomes did not. By contrast, both PEGylated and non-PEGylated liposomes attached to L1 chips without fusion. SPR binding kinetics showed that, in the absence of PEG, the antibody binds the hapten at the surface of lipid bilayers with the affinity of the soluble hapten. The incorporation of PEGylated lipids hinders antibody binding to extents depending on PEGylated lipid fraction and PEG molecular weight. SPR on immobilized liposomes thus appears as a useful technique to optimize formulations of liposomes for targeted therapy.

Botosoa, Eliot. P.; Maillasson, Mike; Mougin-Degraef, Marie; Remaud-Le Saec, Patricia; Gestin, Jean-Francois; Jacques, Yannick; Barbet, Jacques; Faivre-Chauvet, Alain

2011-01-01

403

Anode Performance of Pyrolyzed Bacterial Cellulose in Secondary Lithium-Ion Batteries and the Effect of Added Metal Phthalocyanines  

NASA Astrophysics Data System (ADS)

Electrochemical properties of pyrolyzed bacterial cellulose and the effect of the addition of metal phthalocyanines have been investigated for application of the cellulose to electrodes of lithium-ion batteries. The electrodes made of pyrolyzed bacterial cellulose exhibit good stability and relatively high Coulombic efficiency in charge-discharge cycles. Furthermore, the addition of metal phthalocyanines before pyrolysis remarkably increases the charge-discharge capacities of the pyrolyzed bacterial cellulose. We propose the new application of bacterial cellulose as an electrode active material in rechargeable batteries.

Take, Hiroyoshi; Yamanaka, Shigeru; Ishihara, Masaru; Yoshino, Katsumi

2002-05-01

404

Two-photon absorption cross section of aluminium phthalocyanine excited by a femtosecond Ti:sapphire laser  

SciTech Connect

The two-photon absorption (TPA) cross section is measured to be 543{+-}16 GM for aluminium phthalocyanine excited by a femtosecond Ti:sapphire laser. The TPA cross section at the Ti:sapphire laser wavelength of 800 nm exceeds by more than 40 times the TPA cross section measured earlier at the Nd:YAG laser wavelength of 1064 nm. The role of the resonance TPA enhancement caused by the presence of the real 14815-cm{sup -1} S{sub 1u} level near the virtual 12594-cm{sup -1} level in phthalocyanine is discussed. (nonlinear optical phenomena)

Meshalkin, Yu P [Novosibirsk State Technical University, Novosibirsk (Russian Federation); Chunosova, S S [Institute of Laser Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk (Russian Federation)

2005-06-30

405

Nonlinear grating behavior of phthalocyanine Langmuir--Blodgett films. [NiC d4H d4NH  

SciTech Connect

Optical second-harmonic generation was observed from nickel tetracumylphenoxy phthalocyanine films deposited on quartz by the Langmuir--Blodgett (L-B) technique. The L-B films consist of microcrystallites, i.e., phthalocyanine aggregates, which have a preferred in-plane orientation with respect to the deposition direction. The L-B films also display characteristics of a nonlinear grating with the same periodicity and groove depth over the entire surface. This is to our knowledge the first time that such nonlinear grating behavior has been observed from an organometallic multilayer film.

Neuman, R.D.; Shah, P.; Akki, U. (Department of Chemical Engineering, Auburn University, Auburn, Alabama 36849 (United States))

1992-06-01

406

Near-IR absorbing phthalocyanine derivatives as materials for organic solar cells  

NASA Astrophysics Data System (ADS)

Phthalocyanines (Pcs) are highly conjugated synthetic porphyrin analogs that exhibit high extinction coefficients and hole mobilities, and strong pi-pi interactions. We have developed a general method for the synthesis of peripherally functionalized Pc chromophores using 'click' chemistry, wherein an alkynyl substituted Pc is reacted with an azide, providing an elegant route to the creation of a library of numerous Pcs. We have also developed a simple route to the synthesis of tri- and tetravalent metal Pc derivatives such as titanyl phthalocyanine (TiO Pc) involving solvent-free conditions. Solvent-free conditions are environmentally friendly and industrially economical, and in the present context effectively eliminate the formation of non-metallated phthalocyanine (H 2Pc), a side product often seen in other routes that interferes with their purification. We have also prepared and characterized thin-films of some of these Pcs, TiOPcs in particular, wherein we have developed an easy route to various TiO Pc polymorphs exhibiting different near-IR sensitivities via spin-coating whose optical properties are reminiscent of Phase-I and Phase-II polymorphs of the unmodified TiOPc. Phase-II is particularly interesting as it is photoelectrically active in the near-IR region with a Q-band maximum at ca. 890 nm. We have also fabricated and characterized organic solar cells in both planar heterojunction (PHJ) and bulk heterojunction (BHJ) architectures based on one of these materials, which exhibited good near-IR photoactivity with the absorption spectrum extending up to 1 micrometer in the near-IR. The incident and absorbed photon to current efficiency (IPCE and APCE) spectra showed contributions from the TiOPc in the near-IR region with local maxima around 680 nm and 920 nm, corresponding to the Frenkel and the charge-transfer (CT) bands of the TiOPc, respectively.

Mayukh, Mayank

407

Inhibition of cationic liposomes of (3H)thymidine incorporation into DNA of L1210 cells  

SciTech Connect

The in vitro cytotoxicity of cationic liposomes for L1210 cells was studied by measuring in two hours incubation their effect on (3H) thymidine incorporation into DNA. Liposomes prepared from the mixtures dipalmitoylphosphatidylcholine-cholesterol-stearylamine, egg yolk phosphatidyl-choline-cholesterol-stearylamine and egg yolk phosphatidyl-choline-stearylamine inhibit (3H) thymidine incorporation into L1210 cells DNA. The degree of inhibition increases with incubation time and the concentration of liposomes in the incubations. Liposomes of similar compositions, but without stearylamine (neutral liposomes), did not affect (3H) thymidine incorporation. On the other hand, fluorescence microscopy of cell incubated with liposomes containing 10 mM 6-carboxy fluorescein showed only cationic liposomes adsorbed on the surface of L1210 cells. It is concluded that the inhibition of (3H) thymidine incorporation due to cationic liposomes is partly related to their adsorption on the cell plasma membrane.

Laurent, G.; Laduron, C.; Ruysschaert, J.M.; Deleers, M.

1981-03-01

408

Phosphatidylinositol Liposomes Opsonized by Concanavalin A Stimulate Phosphatidylinositol Turnover in Macrophages.  

National Technical Information Service (NTIS)

Concanavalin A binds specifically to inositol and phosphatidylinositol. In the present study we demonstrate that binding of concanavalin A to liposomes containing phosphatidylinositol influences the uptake of such liposomes by macrophages. Although reside...

N. M. Wassef C. R. Alving

1986-01-01

409

Transport of actin-decorated liposomes along myosin molecules in vitro.  

PubMed

We examined whether actin filaments bound to positively charged liposomes could interact with myosin molecules and induce liposome motility. When liposomes were constructed from the mixture of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and cationic N-[1-(2,3-Dioleoyloxy)propyl]-N,N,N-trimethylammonium (DOTAP), actin filaments bound to the liposomes. The actin-bound liposomes exhibited movement on myosin molecules in the presence of adenosine-5'-triphosphate (ATP). The displacement was almost linearly increased with time and the behavior differed from that of Brownian motion. Furthermore, the presence of 30% DOTAP in liposomes was most effective for transport. These data show that the actomyosin system was successfully integrated into the liposomes and possesses the ability to actively transport useful agents enclosed within the liposomes. PMID:22575445

Iwabuchi, Satoshi; Takahashi, Tetsuji; Hatori, Kuniyuki

2012-04-30

410

Effective gene delivery with liposomal bubbles and ultrasound as novel non-viral system.  

PubMed

We developed the novel liposomal bubbles (Bubble liposomes) containing ultrasound imaging gas, perfluoropropane. Bubble liposomes were made of pegylated liposomes and were smaller than conventional microbubbles. Bubble liposomes also had a function as imaging agents in cardiosonography. In addition, Bubble liposomes could deliver plasmid DNA into various types of cells in vitro without cytotoxicity by the combination of ultrasound. In vivo gene delivery, Bubble liposomes could deliver plasmid DNA into mouse femoral artery by the transdermally exposure of ultrasound. This transfection efficiency was more effectively than lipofection method. Interestingly, the gene expression was only observed at the site of ultrasound exposure. Therefore, we concluded that Bubble liposomes could be good tools to establish tissue-specific gene delivery system as well as ultrasound imaging agents. PMID:17671899

Suzuki, Ryo; Takizawa, Tomoko; Negishi, Yoichi; Utoguchi, Naoki; Maruyama, Kazuo

411

Liposomes as Vehicles for Vaccines: Induction of Humoral, Cellular, and Muscosal Immunity.  

National Technical Information Service (NTIS)

Liposome research has been a major beneficiary of a recent resurgence of interest in vaccine adjuvants (reviewed by van Rooijen and Su, 1989; Gregoriadis, 1990; Alving 1991,1992; Phillips, 1992). Although liposomes were originally developed as models of e...

C. R. Alving

1995-01-01

412

Elastic liposomes bearing meloxicam-beta-cyclodextrin for transdermal delivery.  

PubMed

The ultra-flexible lipid vesicles, the elastic liposomes bearing meloxicam-beta-cyclodextrin complex were prepared for its topical administration with the aim of simultaneously exploiting the favorable properties of both the carriers. The prepared meloxicam-beta-cyclodextrin complex was evaluated using DSC, XRD and FT-IR, which indicates the formation of inclusion complex in a molar ratio of 1:2 of meloxicam and beta-cyclodextrin (beta-CD). The elastic liposomes were prepared by conventional rotary evaporation method and characterized for various parameters such as vesicle shape and surface morphology, size and size distribution, entrapment efficiency, elasticity, stability and in-vitro release pattern. Permeability studies of meloxicam and meloxicam-beta-cyclodextrin complex, as such or incorporated in elastic liposomes performed both across artificial membranes and rat skin highlighted a favorable effect of cyclodextrin on drug permeation rate, due to its solubilizing action. Moreover skin-permeation enhancer property of elastic liposomes has been evidenced. Skin permeation potential of the developed formulation was assessed using confocal laser scanning microscopy (CLSM), which revealed an enhanced permeation of the formulation to the deeper layers of the skin (up to 160 microm) following channel like pathways. Skin permeation profile of elastic liposomal formulation bearing meloxicam-beta-cyclodextrin complex was observed and the investigations revealed an enhanced transdermal flux (12.48+/-0.9 microg/cm(2)/h) and decreased lag time (0.7 h) for meloxicam. The obtained flux was nearly 1.4 and 9.1 times higher than elastic liposomal formulation bearing meloxicam and plain drug solution, respectively (P<0.005). The results indicate that the elastic liposomes may be promising vehicles for the transdermal delivery of meloxicam. PMID:18673264

Jain, Sanjay K; Gupta, Yashwant; Jain, Anekant; Amin, Sadia

2008-07-01

413

Microfluidic directed formation of liposomes of controlled size.  

PubMed

A new method to tailor liposome size and size distribution in a microfluidic format is presented. Liposomes are spherical structures formed from lipid bilayers that are from tens of nanometers to several micrometers in diameter. Liposome size and size distribution are tailored for a particular application and are inherently important for in vivo applications such as drug delivery and transfection across nuclear membranes in gene therapy. Traditional laboratory methods for liposome preparation require postprocessing steps, such as sonication or membrane extrusion, to yield formulations of appropriate size. Here we describe a method to engineer liposomes of a particular size and size distribution by changing the flow conditions in a microfluidic channel, obviating the need for postprocessing. A stream of lipids dissolved in alcohol is hydrodynamically focused between two sheathed aqueous streams in a microfluidic channel. The laminar flow in the microchannel enables controlled diffusive mixing at the two liquid interfaces where the lipids self-assemble into vesicles. The liposomes formed by this self-assembly process are characterized using asymmetric flow field-flow fractionation combined with quasi-elastic light scattering and multiangle laser-light scattering. We observe that the vesicle size and size distribution are tunable over a mean diameter from 50 to 150 nm by adjusting the ratio of the alcohol-to-aqueous volumetric flow rate. We also observe that liposome formation depends more strongly on the focused alcohol stream width and its diffusive mixing with the aqueous stream than on the sheer forces at the solvent-buffer interface. PMID:17451256

Jahn, Andreas; Vreeland, Wyatt N; DeVoe, Don L; Locascio, Laurie E; Gaitan, Michael

2007-04-24

414

Studies of archaebacterial bipolar tetraether liposomes by perylene fluorescence.  

PubMed Central

Membrane packing and dynamics of bipolar tetraether liposomes composed of the polar lipid fraction E (PLFE) from the thermoacidophilic archaebacterium Sulfolobus acidocaldarius have been studied by perylene fluorescence. At a probe-to-PLFE lipid ratio of 1:400, we have detected an unusual fluorescence intensity increase with increasing temperature, while the fluorescence lifetime changed little. As the ratio was decreased, the intensity anomaly was diminished. At 1:3200 and 1:6400, the anomaly disappeared. A remarkable perylene intensity anomaly was also observed in bilayers composed of saturated monopolar diester phosphatidylcholines at their main phase transition temperatures. These results suggest that the intensity anomaly may be due to probe aggregation caused by tight membrane packing. At the same probe-to-lipid ratio (1:400), however, 1, 2-diphytanoyl-sn-glycero-3-phosphocholine (DPhPC) and 1, 2-diphytanoyl-sn-glycero-3-phosphoglycerol (DPhPG) liposomes did not exhibit any intensity anomaly with increasing temperature. This suggests that DPhPC and DPhPG liposomes are more loosely packed than PLFE liposomes; thus the branched methyl groups are not the contributing factor of the tight membrane packing found in PLFE liposomes. Using a multiexcitation method, we have also determined the average (R), in-plane (R(ip)), and out-of-plane (R(op)) rotational rates of perylene in PLFE liposomes at various temperatures (20-65 degrees C). R and R(ip), determined at two different probe-to-lipid ratios (1:400 and 1:3200), both undergo an abrupt increase when the temperature is elevated to approximately 48 degrees C. These data suggest that PLFE liposomes are rigid and tightly packed at low temperatures, but they begin to possess appreciable "membrane fluidity" at temperatures close to the minimum growth temperature ( approximately 50 degrees C) of thermoacidophilic archaebacteria.

Khan, T K; Chong, P L

2000-01-01

415

Electrochemical, SEM/EDS and quantum chemical study of phthalocyanines as corrosion inhibitors for mild steel in 1 mol/l HCl  

NASA Astrophysics Data System (ADS)

The inhibition effect of metal-free phthalocyanine (H2Pc), copper phthalocyanine (CuPc) and copper phthalocyanine tetrasulfuric tetrasodium salt (CuPc·S4·Na4) on mild steel in 1 mol/l HCl in the concentration range of 1.0 × 10-5 to 1.0 × 10-3 mol/l was investigated by electrochemical test, scanning electron microscope with energy dispersive spectrometer (SEM/EDS) and quantum chemical method. The potentiodynamic polarization curves of mild steel in hydrochloric acid containing these compounds showed both cathodic and anodic processes of steel corrosion were suppressed, and the Nyquist plots of impedance expressed mainly as a capacitive loop with different compounds and concentrations. For all these phthalocyanines, the inhibition efficiency increased with the increase in inhibitor concentration, while the inhibition efficiencies for these three phthalocyanines with the same concentration decreased in the order of CuPc·S4·Na4 > CuPc > H2Pc according to the electrochemical measurement results. The SEM/EDS analysis indicated that there are more lightly corroded and oxidative steel surface for the specimens after immersion in acid solution containing 1.0 × 10-3 mol/l phthalocyanines than that in blank. The quantum chemical calculation results showed that the inhibition efficiency of these phthalocyanines increased with decrease in molecule's LUMO energy, which was different from the micro-cyclic compounds.

Zhao, Peng; Liang, Qiang; Li, Yan

2005-12-01

416

Self-assembly and growth of manganese phthalocyanine on an Au(111) surface  

NASA Astrophysics Data System (ADS)

Self-assembly and growth of manganese phthalocyanine (MnPc) molecules on an Au(111) surface is investigated by means of low-temperature scanning tunneling microscopy. At the initial stage, MnPc molecules preferentially occupy the step edges and elbow sites on the Au(111) surface, then they are separately adsorbed on the face-centered cubic and hexagonal closely packed regions due to a long-range repulsive molecule—molecule interaction. After the formation of a closely packed monolayer, molecular islands with second and third layers are observed.

Jiang, Yu-Hang; Liu, Li-Wei; Yang, Kai; Xiao, Wen-De; Gao, Hong-Jun

2011-09-01

417

Very-high-efficiency double-heterostructure copper phthalocyanine\\/C60 photovoltaic cells  

Microsoft Academic Search

We demonstrate an external power conversion efficiency of (3.6+\\/-0.2)% under AM1.5 spectral illumination of 150 mW\\/cm2 (1.5 suns) with vacuum-deposited copper phthalocyanine\\/C60 thin-film double-heterostructure photovoltaic cells incorporating an exciton-blocking layer (EBL). We show that the anode work function influences the photocarrier collection characteristics through the built-in electric field. The cell parameters are less sensitive to the cathode work function, which

P. Peumans; S. R. Forrest

2001-01-01

418

Z-scan study of nonlinear absorption in novel lanthanide bis-phthalocyanines  

NASA Astrophysics Data System (ADS)

We report our results on the nonlinear absorption of novel sandwich lanthanide(III) double-decker complexes BuPc2Ln (BuPc = 2,3,9,10,16,17,23,24-octabutyl-phthalocyaninate; Ln = Eu, Dy, Er, Lu) studied in tetrahydrofuran (THF) solution using open aperture z-scan technique with 350 ps laser pulses at 532 nm. All the compounds exhibit reverse saturable (RSA) absorption. With approaching to the focus a weak saturation of absorption was observed, while at the focus a strong decrease in transmittance took place. Employing the rate equations formalism we demonstrate RSA being mainly contributed by the triplet state absorption.

Karpo, Alexey B.; Pushkarev, Victor E.; Krasovskii, Vitaly I.; Tomilova, Larisa G.

2012-12-01

419

Electrical properties of hybrid planar diode based on palladium phthalocyanine and titanium dioxide  

NASA Astrophysics Data System (ADS)

This work presents experimental studies of a planar diode made of the layers of indium tin oxide, titanium dioxide, palladium phthalocyanine and gold. The current rectification ratio was 105 at 1.5 V. The analysis of the electrical properties of the system was based on small signal complex capacitance spectra measured in the frequency range of 25 Hz — 1 MHz at different values of bias. No depletion region at the TiO2/PdPc interface was observed. Forward bias specifically affected both parts of the complex capacitance and the observed effect probably resulted from the rearrangement of charge carriers injected into the organic layer.

Jarosz, G.; Ko?cielska, B.; Signerski, R.

2013-01-01

420

Band gap states of copper phthalocyanine thin films induced by nitrogen exposure  

NASA Astrophysics Data System (ADS)

The impact of 1 atm N2 gas exposure on the electronic states of copper phthalocyanine thin films was investigated using ultrahigh-sensitivity ultraviolet photoelectron spectroscopy. The highest occupied molecular orbital band of the film showed a drastic reversible change in the bandwidth and band shape as well as in the energy position upon repeated cycles of N2 exposure and subsequent annealing. Furthermore, two types of gap-state densities with Gaussian and exponential distributions appeared after the exposure and disappeared due to the annealing. These changes are ascribed to a weak disorder in the molecular packing structure induced by N2 diffusion into the film.

Sueyoshi, Tomoki; Kakuta, Haruya; Ono, Masaki; Sakamoto, Kazuyuki; Kera, Satoshi; Ueno, Nobuo

2010-03-01

421

Enhanced photoconductivity of organic single-layered photoreceptor from bisazo\\/phthalocyanine composite  

Microsoft Academic Search

An organic single-layered photoreceptor (SLPR), where 2,5-bis(1?-azo-2?-hydroxy-3?-naphthoyl-o-chloroanide) oxazole\\/oxititanium phthalocyanine composite (O-bisazo\\/TiOPc composite) was used as the charge generation material (CGM) and N,N?-diethyl-4-aminobenzaldehyde-1-phenyl-1?-(?-naphthyl)-hydrazone (DENPH) as the charge transportation material (CTM), was prepared by the dip coating method and its photoconductivity was studied under the exposure of various wavelengths. It was found that such obtained SLPR showed much better photoconductivity than those

Zheng-Long Yang; Hong-Zheng Chen; Min-Min Shi; Chao Pan; Mang Wang

2005-01-01

422

Copper-phthalocyanine encapsulated into zeolite-Y with high Si/Al: An EPR study  

NASA Astrophysics Data System (ADS)

Copper (II) phthalocyanine (CuPc) molecules encapsulated into zeolite-Y with Si/Al ratios of 2.7 and 410 were prepared by an in situ synthesis and characterized by UV-Vis and electron paramagnetic resonance (EPR) spectroscopies. Resolved Cu-hyperfine and N-superhyperfine structures were observed in the EPR spectrum of CuPc encapsulated into zeolite-Y with a high Si/Al ratio. UV-Vis and EPR studies as well as theoretical calculations suggest that the encapsulated CuPc molecule was distorted in zeolite-Y with keeping of the square-planar symmetry around the center copper (II) ion.

Yahiro, Hidenori; Kimoto, Kunihiro; Yamaura, Hiroyuki; Komaguchi, Kenji; Lund, Anders

2005-10-01

423

Absorption spectrophotometric, fluorescence, transient absorption and quantum chemical investigations on fullerene\\/phthalocyanine supramolecular complexes  

Microsoft Academic Search

The present paper reports the photophysical investigations on supramolecular interaction of a phthalocyanine derivative, namely, 2,9,16,23-tetra-tert-butyl-29H,31H-Pc (1) with C60 and C70 in toluene. The binding constants of the C60 and C70 complexes of 1 are estimated to be 27,360 and 25,205dm3, respectively. Transient absorption measurements in the visible region establishes that energy transfer from C60*T (and C70*T) to 1 occurs

Anamika Ray; Kotni Santhosh; Sumanta Bhattacharya

2011-01-01

424

Improvement of the performance of a hydroxyaluminum phthalocyanine photoelectrochemical cell by a phthalic acid treatment  

SciTech Connect

Effects of a phthalic acid treatment on the performance of hydroxyaluminum phthalocyanine (PcAlOH) photoelectrochemical cells have been investigated. PcAlOH thin films have been prepared by vacuum deposition on tin oxide substrates. The acid treatment induces a dimorphic transformation of the -form PcAlOH to a new polymorph n-PcAlOH absorbing on a larger range (550-900 nm). Photoelectrochemical studies with BQ/HQ and I/sub 3//sup -//I/sup -/ redox couples showed that the phthalic acid treatment improved strongly the performance of PcAlOH cells.

Perrier, G.; Dao, L.H.

1987-05-01

425

Synthesis of a novel water-soluble zinc phthalocyanine and its CT DNA-damaging studies  

NASA Astrophysics Data System (ADS)

A novel 3-(4-methoxybenzylamino) propanoic acid substituted water-soluble zinc phthalocyanine (CNPcZn) was synthesized. The interaction between CNPcZn with calf thymus DNA (CT DNA) was studied using spectroscopic methods. The studies indicated that CNPcZn has strong affinity to CT DNA, and furthermore, CNZnPc showed excellent photodamaging activity to CT DNA. Above results indicated that such CNPcZn has great potential to be used as an effective photosensitizer in the field of photodynamic therapy.

Wang, Tianhui; Wang, Ao; Zhou, Lin; Lu, Shan; Jiang, Weiwei; Lin, Yun; Zhou, Jiahong; Wei, Shaohua

2013-11-01

426

Atomic structure of nickel phthalocyanine probed by X-ray absorption spectroscopy and density functional simulations  

NASA Astrophysics Data System (ADS)

The local atomic structure of Ni in nickel phthalocyanine was studied by K-edge X-ray absorption fine structure spectroscopy. The obtained inter atomic nickel-nitrogen distance differs from the reference X-ray diffraction data so an additional study was performed within density functional theory framework. The justification of the used theoretical approach was provided by a comparison of theoretical free electron densities of states with experimental Ni K-edge X-ray absorption near edge spectra. The refined Ni local environment retain the reference structure of the molecule except for the length of Ni-N bond which increases to 1.90 Å.

Avakyan, L. A.; Manukyan, A. S.; Mirzakhanyan, A. A.; Sharoyan, E. G.; Zubavichus, Y. V.; Trigub, A. L.; Kolpacheva, N. A.; Bugaev, L. A.

2013-03-01

427

Electronic Structure of the Organic Semiconductor Vanadyl Phthalocyanine (VO-Pc)  

SciTech Connect

The electronic structure of thin films of the organic semiconductor vanadyl phthalocyanine has been studied using synchrotron radiation-excited resonant soft X-ray emission spectroscopy, resonant inelastic soft X-ray scattering, X-ray absorption spectroscopy, and X-ray photoemission spectroscopy. The C, N, V, and O partial densities of states for both the valence and conduction bands have been determined, as well as the core level electronic structure. Good agreement was found between the experimental measurements of the valence and conduction bands, and the results of a density functional calculation.

Zhang,Y.; Learmonth, T.; Wang, S.; Matsura, A.; Downes, J.; Plucinski, L.; Bernardis, S.; O'Donnell, C.; Smith, K.

2007-01-01

428

Bending stress induced improved chemiresistive gas sensing characteristics of flexible cobalt-phthalocyanine thin films  

NASA Astrophysics Data System (ADS)

We report chemiresistive gas sensing characteristics of cobalt phthalocyanine films deposited on flexible bi-axially oriented polyethylene terephthalate substrates. Charge carrier mobility in these films systematically decreases upon bending, which implies that bending reduces ?-? interactions among molecules. At room temperature, these films exhibited a reversible change in resistance on exposure to ammonia (5-50 ppm) along with high sensitivity and selectivity as well as fast response and recovery. The chemiresistive sensing properties were found to improve significantly under bend conditions owing to creation of more numbers of interaction sites.

Singh, Ajay; Kumar, Ashwini; Kumar, Arvind; Samanta, S.; Joshi, Nirav; Balouria, Vishal; Debnath, A. K.; Prasad, R.; Salmi, Z.; Chehimi, M. M.; Aswal, D. K.; Gupta, S. K.

2013-04-01

429

Laser-induced hole filling and spectral diffusion of aluminum phthalocyanine tetrasulfonate in hyperquenched glassy films  

SciTech Connect

Laser-induced hole filling and spectral diffusion for the dye aluminum phthalocyanine tetrasulfonate in hyperquenched glassy films of water, ethanol, and methanol are investigated. Burning multiple holes into these films reveals a dependence on the burn direction, which is explained by the asymmetry of the antihole produced in the burning process. Spectral diffusion rates are shown to be dependent on sample annealing at temperatures well below the glass transition temperature, T{sub g}. This is interpreted in terms of a {beta}-relaxation process of the glass and is identified with transport of free volume. {copyright} {ital 1999 American Institute of Physics.}

Reinot, T.; Hayes, J.M.; Small, G.J. [Ames Laboratory and Department of Chemistry, Iowa State University, Ames, Iowa 50011 (United States)

1999-03-01

430

Resonant inelastic x-ray scattering studies of the organic semiconductor copper phthalocyanine  

SciTech Connect

We report resonant inelastic x-ray scattering (RIXS) measurements on polycrystalline and single crystal samples of the organic semiconductor {beta}-copper phthalocyanine (CuPc) as well as time dependent density functional theory calculations of the electronic properties of the CuPc molecule. Resonant and nonresonant excitations were measured along the three crystal axes with 120 meV resolution. We observe molecular excitations as well as charge-transfer excitons along certain crystal directions and compare our data with the calculations. Our results demonstrate that RIXS is a powerful tool for studying excitons and other electronic excitations in organic semiconductors.

Kodituwakku, C. N.; Burns, C. A.; Said, A. H.; Sinn, H.; Wang, X.; Gog, T.; Casa, D. M.; Tuel, M.; Western Michigan Univ.; DESY, Hasylab

2008-01-01

431

Magnetic circularly polarized luminescence of zinc phthalocyanine in an argon matrix  

SciTech Connect

The magnetic circularly polarized luminescence (MCPL) of the Q transition of zinc phthalocyanine has been measured in an argon matrix. These are the first such measurements for a matrix-isolated sample and support previous interpretations that require a crystal-field-stabilized Jahn-Teller splitting in the {sup 1}E{sub u}({pi}{sup *}) excited state. A moment analysis indicates the presence of a Ham effect which reduces the orbital angular momentum of this state by about 30%. Energy transfer between inequivalent sites in the matrix results in a red shift of the emission relative to the Q(0,0) absorption band.

Metcalf, D.H.; VanCott, T.C.; Snyder, S.W.; Schatz, P.N. (Univ. of Virginia, Charlottesville (USA)); Williamson, B.E. (Univ. of Canterbury, Christchurch (New Zealand))

1990-04-05

432

Near monolayer deposition of palladium phthalocyanine and perylene tetracarboxylic diimide on Au(001): A STM study  

NASA Astrophysics Data System (ADS)

Near monolayer deposition of palladium phthalocyanine (PdPc) or perylene tetracarboxylic diimide (PTCDI) on the Au(001)-5× 28 reconstructed surface leads to the formation of well ordered molecular assemblies, as observed by means of scanning tunneling microscopy. The PdPc lattice shows locally domains with square or rectangular symmetry having different molecular densities. The underlying gold surface reconstruction remains stable after PdPc deposition, indicating a weak interaction between PdPc and the gold surface. As in the PTCDA case, the PTCDI unit mesh is centered rectangular which is attributed to the formation of H bonds in the lattice.

Guillermet, O.; Glachant, A.; Mossoyan, M.; Mossoyan, J. C.

2006-03-01

433

Polyion complex micelles incorporating poly (aryl benzyl ether) dendritic phthalocyanine: effective photosensitizers for enhanced photodynamic therapy  

NASA Astrophysics Data System (ADS)

A novel series of zinc (II) phthalocyanines bearing four poly (aryl benzyl ether) dendritic substituents with carboxylic acid functionalities (Gn-DPcZn (Gn=n-generation dendrimer, n=1-2)) loaded polymeric micelles (Gn-DPcZn/m) were formed. The time-dependent intracellular uptake of Gn-DPcZn in RPE cells increased as they were incorporated into micelles, but inversely correlated with the generation. The photocytoxity of Gn-DPcZn was improved by incorporation into polymeric micelles and increased with the generation.

Chen, Kuizhi; Yu, Ming; Zhang, Hong; Ma, Dongdong; Pang, Shujuan; Huang, Wei; Peng, Yiru

2012-12-01

434

Metamagnetic Transition and Its Related Magnetocapacitance Effect in Phthalocyanine-Molecular Conductor Exhibiting Giant Magnetoresistance  

NASA Astrophysics Data System (ADS)

The magnetization and transport properties of iron-phthalocyanine molecular conductors are investigated under pulsed high magnetic fields up to 55 T. The metamagnetic transition is observed at approximately 14 T, where conductivity is enhanced. Below this transition, the \\tan ? (=?\\prime\\prime/?\\prime) in the dielectric constants shows a monotonic decrease as the magnetic field strength increases, indicating that the magnetic field stabilizes the charge order. On the verge of this transition, the dielectric constants show a hysteresis below the weak-ferromagnetic transition temperature (6 K), suggesting that the ?-electron charge order contributes to the weak ferromagnetism.

Hanasaki, Noriaki; Tateishi, Takuma; Tajima, Hiroyuki; Kimata, Motoi; Tokunaga, Masashi; Matsuda, Masaki; Kanda, Akinori; Murakawa, Hiroshi; Naito, Toshio; Inabe, Tamotsu

2013-09-01

435

Phthalocyanine-based fluorescent chemosensor for the sensing of Zn (II) in dimethyl sulfoxide-acetonitrile  

Microsoft Academic Search

A tetra-substituted phthalocyanine based on 4-[2-(4-nitrophenoxy)ethoxy]phthalonitrile carrying nitrophenyl group for the\\u000a sensing of Zn2+ has been prepared and characterized by elemental analysis, FT-IR, 1H and 13C NMR, and MS spectral data. The sensing of Zn2+ is based on the fluorescence quenching of Pc. Both absorbance and fluorescence spectra of ZnPc exhibit distinct changes in\\u000a visible region in response to treatment

Yasemin Ça?lar; Nurhan Gümrükçüo?lu; Ece Tu?ba Saka; Miraç Ocak; Halit Kantekin; Ümmühan Ocak

436

Anomalous large nonlinearity of thin SnCl phthalocyanine films observed upon pulsed laser excitation  

Microsoft Academic Search

The nonlinear susceptibility of thin stannum dichloride phthalocyanine (SnClPc) films was studied by the method of degenerate four-wave mixing (DFWM) using the second-harmonic 532-nm, 10-ns pulses from a single-mode, TEM, 1.5-mJ Nd{sup 3+}:YAG laser and by the method of nonlinear lens (the Z-scan method). The intensity of the first-order self-diffraction upon the DFWM on dynamic gratings induced in SnClPc films

A A Borshch; M S Brodin; A B Verbitskii; Ya I Vertsimakha; V I Volkov; V R Lyakhovetskii

2002-01-01

437

Photodynamic therapy disinfection of carious tissue mediated by aluminum-chloride-phthalocyanine entrapped in cationic liposomes: an in vitro and clinical study  

Microsoft Academic Search

Photodynamic therapy (PDT) is a technique employed in the treatment of several superficial infections, such as caries. PDT\\u000a uses a non-toxic drug termed photosensitizer (PS) followed by light irradiation. The cytotoxic effects of the therapy are\\u000a related to the production of reactive species produced after light activation of a photosensitizer, which reacts with surrounding\\u000a molecules and disrupts several of the

João Paulo F. Longo; Soraya C. Leal; Andreza R. Simioni; Maria de Fátima Menezes Almeida-Santos; Antônio C. Tedesco; Ricardo B. Azevedo

438

Liposomal-Glutathione Provides Maintenance of Intracellular Glutathione and Neuroprotection in Mesencephalic Neuronal Cells  

Microsoft Academic Search

A liposomal preparation of glutathione (GSH) was investigated for its ability to replenish intracellular GSH and provide neuroprotection\\u000a in an in vitro model of Parkinson’s disease using paraquat plus maneb (PQMB) in rat mesencephalic cultures. In mixed neuronal\\/glial\\u000a cultures depleted of intracellular GSH, repletion to control levels occurred over 4 h with liposomal-GSH or non-liposomal-GSH\\u000a however, liposomal-GSH was 100-fold more potent;

Gail D. ZeevalkLaura; Laura P. Bernard; F. T. Guilford

2010-01-01

439

Acoustic characterization of liposome suspensions and Optison® at 3.5 MHz  

Microsoft Academic Search

Liposomes-phospholipid vesicles that can encapsulate both gas and fluid-are currently being developed as contrast agents and vehicles for targeted drug delivery. The backscattering coefficient and attenuation of liposome suspensions were measured at 3.5 MHz as a function of liposome concentration and compared to those of Optison®. The backscattering coefficient of liposomes at concentrations in excess of 1.15×108\\/ml exceeds that of

Constantin-C. Coussios; Christy K. Holland; Ludwika Jakubowska; Shao-Ling Huang; Robert C. MacDonald; Ashwin Nagaraj; David D. McPherson

2003-01-01

440

Interaction of targeted liposomes with primary cultured hepatic stellate cells: involvement of multiple receptor systems  

Microsoft Academic Search

Abstract Background\\/Aims: For designing a versatile liposomal drug carrier to hepatic stellate cells (HSC), the interaction of mannose 6-phosphate human serum albumin (M6P-HSA) liposomes with cultured cells was studied. Methods: M6P-HSA was covalently coupled to the liposomal surface and the uptake and binding of 3H-labelled M6P-HSA liposomes by primary rat HSC and liver endothelial cells was determined. The targeting ability

Joanna E. Adrian; Klaas Poelstra; Gerrit L. Scherphof; Grietje Molema; Dirk K. F. Meijer; Catharina Reker-Smit; Henriëtte W. M. Morselt; Jan A. A. M. Kamps

2006-01-01

441

Stabilized liposomes with phospholipid polymers and their interactions with blood cells  

Microsoft Academic Search

To stabilize a phospholipid liposome, addition of various water-soluble polymers into a liposomal aqueous suspension was investigated. The water-soluble polymers were poly(ethylene oxide) (PEO), poly(N-vinyl pyrrolidone) (PVPy) and poly[2-methacryloyloxyethyl phosphorylcholine(MPC)], and poly[MPC-co-n-butyl methacrylate(BMA)]. The gel–liquid crystal transition temperature (Tc) of the diparmitoylphosphatidylcholine (DPPC) liposome was not changed by addition of these polymers significantly. However, membrane fluidity of DPPC liposome treated

Kazuhiko Ishihara; Rieko Tsujino; Mika Hamada; Noriko Toyoda; Yasuhiko Iwasaki

2002-01-01

442

Liposome Dehydration on Nitrocellulose and Its Application in a Biotin Immunoassay  

Microsoft Academic Search

The feasibility of utilizing dehydrated liposomes in the development of a simple immunoassay device for point-of-care diagnostics or field assays was demonstrated. The recovery of liposomes after a cycle of dehydration and rehydration was studied using biotin-tagged, dye-loaded liposomes with antibiotin antibodies immobilized in a defined zone on nitrocellulos