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Sample records for liposomal geiv phthalocyanine

  1. In vivo fluorescence and photodynamic activity of zinc phthalocyanine administered in liposomes.

    PubMed

    van Leengoed, H L; Cuomo, V; Versteeg, A A; van der Veen, N; Jori, G; Star, W M

    1994-05-01

    Zinc(II) phthalocyanine, a hydrophobic photosensitiser, was incorporated in unilamellar liposomes and studied in vivo for fluorescence kinetics and photodynamic activity. An observation chamber mounted in a dorsal skinfold of female WAG/Rij rats was used as a model system. In the chamber, an isogeneic mammary carcinoma was transplanted in the subcutaneous tissue. Phthalocyanine fluorescence was excited at 610 nm with a power density of 0.25 mW cm-2 and was detected above 665 nm through a high-pass filter using a two-stage image intensifier coupled to a charge-coupled device (CCD) camera. Following i.v. administration of 0.14 mg kg-1 of the drug, the fluorescence pharmacokinetics of the dye in vasculature, normal tissue and tumour tissue was determined as a function of time. Tumour fluorescence increased slowly to a maximum about 3 h post injection (p.i.), and remained well above the normal tissue fluorescence till 24 h p.i. Fluorescence in the circulation was always stronger than in the tissues. A treatment light dose at a wavelength of 675 nm was delivered 24 h p.i. One group of six animals received a total light dose of 150 J cm-2 (100 mW cm-2). A second group of six animals received a total light dose of 450 J cm-2 at the same dose rate. Vascular damage resulting from treatment was observed only at the final stages of the irradiation, despite the relatively high levels of fluorescence in the circulation. Immediate post-treatment (re)transplantation of the content of the chamber into the flank always resulted in tumour regrowth, confirming the presence of viable tumour cells following photodynamic therapy (PDT). When the chamber was left intact, the light dose of 450 J cm-2 yielded complete tissue necrosis. The role of the dye-carrier complex in shielding the vascular surrounding from photoproducts was studied in a third group of animals. The presence of peroxides was demonstrated in the serum of these animals after PDT with zinc phthalocyanine in liposomes (Zn

  2. Liposomes.

    PubMed

    Posner, Robert

    2002-09-01

    Robert Posner has 40 years of experience in skin care bench chemistry, product development, and sales and marketing. Working closely with dermatologists and plastic surgeons, Posner is a former member of the NY State Hospital Pharmacists Association, the American Pharmaceutical Association, and the American Association of Hospital Pharmacists. Currently, Posner sits on the Board of Directors of EMDA (Esthetic Manufacturers and Distributors Association). Posner has written numerous articles for Les Nouvelles Esthetiques Magazine, is presently a consultant for Day Spa Magazine, and had been one of only two non-dermatologists on a consultant basis with Cosmetic Dermatology Journal. Posner's company--ABBE Cosmetic Group International in Farmingdale, NY--formulates and manufactures skin care products for many well-known companies in the beauty industry. For many years, both the bench chemist and the dermatologist have been concerned with developing an ideal base for deliverance of 'actives' to the human epidermis. As is common knowledge, the skin is a protective organ which allows very few materials to penetrate. Some bases are unable to work effectively because of their relative inability to penetrate the stratum corneum; for example, some notable actives such as collagen and elastin are molecules too large to penetrate effectively. With the liposome at our command however, we can carry and then release an active into several layers of epidermis. We can release both oil- and water-soluble actives, and at the same time control the feel and effectiveness of a topical application. This article will examine the liposome: what it is, how it works, and how products made with liposomes can benefit dermatology. PMID:12847740

  3. Photodynamic performance of zinc phthalocyanine in HeLa cells: A comparison between DPCC liposomes and BSA as delivery systems.

    PubMed

    M Garcia, Angélica; de Alwis Weerasekera, Hasitha; Pitre, Spencer P; McNeill, Brian; Lissi, Eduardo; Edwards, Ana M; Alarcon, Emilio I

    2016-10-01

    Comparable intracellular concentrations (≈30pmol/10(6) cells) of bovine serum albumin-ZnPc (BSA) adduct outperformed dipalmitoyl-phosphatidyl-choline (DPPC) liposomes containing ZnPc at photodynamic-killing of human cervical cancer cells (HeLa) after only 15min of irradiation using red light (λ>620nm, 30W/cm(2)). This result could not be simply explained in terms of dye aggregation within the carrier, since in the liposomes the dye was considerably less aggregated than in bovine serum albumin, formulation that was capable to induce cell apoptosis upon red light exposure. Thus, using specific organelle staining, our cumulative data points towards intrinsic differences in intra-cellular localization depending on the cargo vehicle used, being ZnPc:BSA preferentially located in the near vicinity of the nucleus and in the Golgi structures, while the liposomal formulation ZnPc:DPPC was preferentially located in cellular membrane and cytoplasm. In addition to those differences, using real-time advanced fluorescence lifetime imaging of HeLa cells loaded with the photosensitizer contained in the different vehicles, we have found that only for the ZnPc:BSA formulation, there was no significant changes in the fluorescence lifetime of the photosensitizer inside the cells. This contrasts with the in situ≈two-fold reduction of the fluorescence lifetime measured for the liposomal ZnPc formulation. Those observations point towards the superiority of the protein to preserve dye aggregation, and its photochemical activity, post-cell uptake, demonstrating the pivotal role of the delivery vehicle at determining the ultimate fate of a photosensitizer. PMID:27614847

  4. Photodynamic performance of zinc phthalocyanine in HeLa cells: A comparison between DPCC liposomes and BSA as delivery systems.

    PubMed

    M Garcia, Angélica; de Alwis Weerasekera, Hasitha; Pitre, Spencer P; McNeill, Brian; Lissi, Eduardo; Edwards, Ana M; Alarcon, Emilio I

    2016-10-01

    Comparable intracellular concentrations (≈30pmol/10(6) cells) of bovine serum albumin-ZnPc (BSA) adduct outperformed dipalmitoyl-phosphatidyl-choline (DPPC) liposomes containing ZnPc at photodynamic-killing of human cervical cancer cells (HeLa) after only 15min of irradiation using red light (λ>620nm, 30W/cm(2)). This result could not be simply explained in terms of dye aggregation within the carrier, since in the liposomes the dye was considerably less aggregated than in bovine serum albumin, formulation that was capable to induce cell apoptosis upon red light exposure. Thus, using specific organelle staining, our cumulative data points towards intrinsic differences in intra-cellular localization depending on the cargo vehicle used, being ZnPc:BSA preferentially located in the near vicinity of the nucleus and in the Golgi structures, while the liposomal formulation ZnPc:DPPC was preferentially located in cellular membrane and cytoplasm. In addition to those differences, using real-time advanced fluorescence lifetime imaging of HeLa cells loaded with the photosensitizer contained in the different vehicles, we have found that only for the ZnPc:BSA formulation, there was no significant changes in the fluorescence lifetime of the photosensitizer inside the cells. This contrasts with the in situ≈two-fold reduction of the fluorescence lifetime measured for the liposomal ZnPc formulation. Those observations point towards the superiority of the protein to preserve dye aggregation, and its photochemical activity, post-cell uptake, demonstrating the pivotal role of the delivery vehicle at determining the ultimate fate of a photosensitizer.

  5. METAL PHTHALOCYANINES

    DOEpatents

    Frigerio, N.A.

    1962-03-27

    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)

  6. Phthalocyanine polymers

    NASA Technical Reports Server (NTRS)

    Achar, B. N.; Fohlen, G. M.; Parker, J. A. (Inventor)

    1985-01-01

    A method of forming 4,4',4'',4''' -tetraamino phthalocyanines involves reducing 4,4',4'',4''' -tetranitro phthalocyanines, polymerizing the metal tetraamino phthalocyanines with a tetracarboxylic dianhydride (preferably aromatic) or copolymerizing with a tetracarboxylic dianhydride and a diamine (preferably also aromatic) to produce amic acids which are then dehydrocyclized to imides. Thermally and oxidatively stable polymers result which form tough, flexible films, varnishes, adhesives, and fibers.

  7. Glycosylated Metal Phthalocyanines.

    PubMed

    Hanack, Michael

    2015-11-10

    In the first part; the syntheses of mono-; di-; and tetra-glycosylated phthalonitriles is described; which are the most used starting materials for the preparation of the corresponding glycosylated metal (mostly zinc) phthalocyanines. In the second section; the preparation of symmetric and unsymmetric mono-; tetra-; and octa- glycosylated zinc phthalocyanines are reviewed; in which the sugar is attached to the phthalocyanine macrocycle; either anomerically or via another one of its OH-groups.

  8. Metal phthalocyanine polymers

    NASA Technical Reports Server (NTRS)

    Achar, B. N.; Fohlen, G. M.; Parker, J. A. (Inventor)

    1984-01-01

    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. These tetracarboxylic acids are then polymerized by heat to sheet polymers which have superior heat and oxidation resistance. The metal is preferably a divalent metal having an atomic radius close to 1.35A.

  9. Method of solubilizing phthalocyanines and metallophthalocyanines

    DOEpatents

    Rathke, Jerome W.; Chen, Michael J.; Fendrick, Carol M.

    1997-11-04

    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.

  10. Method of solubilizing phthalocyanines and metallophthalocyanines

    DOEpatents

    Rathke, Jerome W.; Chen, Michael J.; Fendrick, Carol M.

    1997-01-01

    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.

  11. New Directions in Phthalocyanine Pigments

    NASA Technical Reports Server (NTRS)

    Vandemark, Michael R.

    1992-01-01

    The objectives were the following: (1) investigation of the synthesis of new phthalocyanines; (2) characterization of the new phthalocyanines synthesized; (3) investigate the properties of the newly synthesized phthalocyanines with emphasis on UV protection of plastics and coatings; and (4) utilize quantum mechanics to evaluate the structural relationships with possible properties and synthetic approaches. The proposed research targeted the synthesis of phthalocyanines containing an aromatic bridge between two phthalocyanine rings. The goal was to synthesize pigments which would protect plastics when exposed to the photodegradation effects of the sun in space. The stability and extended conjugation of the phthalocyanines offer a unique opportunity for energy absorption and numerous radiative and non-radiative energy loss mechanisms. Although the original targeted phthalocyanines were changed early in the project, several new and unique phthalocyanine compounds were prepared. The basic goals of this work were met and some unique and unexpected outcomes of the work were the result of the integral use of quantum mechanics and molecular modeling with the synthetic effort.

  12. Site-specific conjugation of single domain antibodies to liposomes enhances photosensitizer uptake and photodynamic therapy efficacy

    NASA Astrophysics Data System (ADS)

    Broekgaarden, M.; van Vught, R.; Oliveira, S.; Roovers, R. C.; van Bergen En Henegouwen, P. M. P.; Pieters, R. J.; van Gulik, T. M.; Breukink, E.; Heger, M.

    2016-03-01

    Photodynamic therapy for therapy-resistant cancers will greatly benefit from targeted delivery of tumor photosensitizing agents. In this study, a strategy for the site-specific conjugation of single domain antibodies onto liposomes containing the photosensitizer zinc phthalocyanine was developed and tested.Photodynamic therapy for therapy-resistant cancers will greatly benefit from targeted delivery of tumor photosensitizing agents. In this study, a strategy for the site-specific conjugation of single domain antibodies onto liposomes containing the photosensitizer zinc phthalocyanine was developed and tested. Electronic supplementary information (ESI) available: Materials and methods. See DOI: 10.1039/c6nr00014b

  13. Doped colorimetric assay liposomes

    DOEpatents

    Charych, Deborah; Stevens, Raymond C.

    2001-01-01

    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.

  14. New directions in phthalocyanine pigments

    NASA Technical Reports Server (NTRS)

    Trinh, Diep VO

    1994-01-01

    Phthalocyanines have been used as a pigment in coatings and related applications for many years. These pigments are some of the most stable organic pigments known. The phthalo blue and green pigments have been known to be ultraviolet (UV) stable and thermally stable to over 400 C. These phthalocyanines are both a semiconductor and photoconductor, exhibiting catalytic activity and photostabilization capability of polymers. Many metal free and metallic phthalocyanine derivatives have been prepared. Development of the new classes of phthalocyanine pigment could be used as coating on NASA spacecraft material such as glass to decrease the optical degradation from UV light, the outside of the space station modules for UV protection, and coating on solar cells to increase lifetime and efficiency.

  15. Fluorescence resonance energy transfer measurements as a tool to detect fusion and drug exchange in liposomal suspensions

    NASA Astrophysics Data System (ADS)

    Hilfinker, Rolf; Willi, Annette; Isele, Ute; van Hoogevest, Peter

    1994-03-01

    Zinc-(II)-phthalocyanine (ZnPc) is a drug that can potentially be used in photodynamic therapy. A promising formulation approach for the strongly hydrophobic ZnPc is to embed the molecule in liposomes. CGP 55847 is such a liposomal ZnPc formulation. From our data, we could conclude that approximately one quarter of the drug molecules were only loosely bound to the liposomes and exchanged between them with a relaxation time of about 15 min. Energy transfer measurements before and after the lyophilization process revealed that the liposomes were stable when suspended in a 10% lactose solution, i.e. no fusion of liposomes took place. In aqueous solution, however, lyophilization induced fusion of liposomes to a small extent with a concomitant increase in size.

  16. 21 CFR 73.3124 - Phthalocyanine green.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Phthalocyanine green. 73.3124 Section 73.3124 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3124 Phthalocyanine green. (a) Identity. The color additive is phthalocyanine green (CAS Reg. No. 1328-53-6), Colour Index No. 74260. (b)...

  17. 21 CFR 73.3124 - Phthalocyanine green.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Phthalocyanine green. 73.3124 Section 73.3124 Food... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3124 Phthalocyanine green. (a) Identity. The color additive is phthalocyanine green (CAS Reg. No. 1328-53-6), Colour Index No. 74260. (b)...

  18. 21 CFR 73.3124 - Phthalocyanine green.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3124 Phthalocyanine green. (a) Identity. The color additive is phthalocyanine green (CAS Reg. No. 1328-53-6), Colour Index No. 74260. (b) Uses... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Phthalocyanine green. 73.3124 Section 73.3124...

  19. 21 CFR 73.3124 - Phthalocyanine green.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... COLOR ADDITIVES EXEMPT FROM CERTIFICATION Medical Devices § 73.3124 Phthalocyanine green. (a) Identity. The color additive is phthalocyanine green (CAS Reg. No. 1328-53-6), Colour Index No. 74260. (b) Uses... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Phthalocyanine green. 73.3124 Section 73.3124...

  20. Phthalocyanine cathode materials for secondary lithium cells

    SciTech Connect

    Tamaki, J.; Yamaji, A.

    1982-01-01

    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.

  1. Gold liposomes

    SciTech Connect

    Hainfeld, J.F.

    1996-12-31

    Lipids are an important class of molecules, being found in membranes, HDL, LDL, and other natural structures, serving essential roles in structure and with varied functions such as compartmentalization and transport. Synthetic liposomes are also widely used as delivery and release vehicles for drugs, cosmetics, and other chemicals; soap is made from lipids. Lipids may form bilayer or multilammellar vesicles, micelles, sheets, tubes, and other structures. Lipid molecules may be linked to proteins, carbohydrates, or other moieties. EM study of this essential ingredient of life has lagged, due to lack of direct methods to visualize lipids without extensive alteration. OsO4 reacts with double bonds in membrane phospholipids, forming crossbridges. This has been the method of choice to both fix and stain membranes, thus far. An earlier work described the use of tungstate clusters (W{sub 11}) attached to lipid moieties to form lipid structures and lipid probes. With the development of gold clusters, it is now possible to covalently and specifically link a dense gold sphere to a lipid molecule; for example, reacting a mono-N-hydroxysuccinimide Nanogold cluster with the amino group on phosphatidyl ethanolaminine. Examples of a gold-fatty acid and a gold-phospholipid are shown.

  2. Liposome technology. Volume I: Preparation of liposomes

    SciTech Connect

    Gregoriadis, G.

    1984-01-01

    These three volumes cover liposome technology in pharmacology and medicine. Contributors emphasize methodology used in their own laboratories, and include a brief introduction, coverage of relevant literature, applications and critical evaluations for the methods they describe. Volume I examine methods for the preparation of liposomes and auxiliary techniques.

  3. Functionalized liposome purification via Liposome Extruder Purification (LEP).

    PubMed

    Alves, Nathan J; Cusick, William; Stefanick, Jared F; Ashley, Jonathan D; Handlogten, Michael W; Bilgicer, Basar

    2013-09-01

    Liposome Extruder Purification (LEP) allows for the rapid purification of diverse liposome formulations using the same extrusion apparatus employed during liposome formation. The LEP process provides a means for purifying functionalized liposomes from non-conjugated drug or protein contaminants with >93% liposome recovery and >93% contaminant removal in a single step.

  4. Liposomes as nanomedical devices

    PubMed Central

    Bozzuto, Giuseppina; Molinari, Agnese

    2015-01-01

    Since their discovery in the 1960s, liposomes have been studied in depth, and they continue to constitute a field of intense research. Liposomes are valued for their biological and technological advantages, and are considered to be the most successful drug-carrier system known to date. Notable progress has been made, and several biomedical applications of liposomes are either in clinical trials, are about to be put on the market, or have already been approved for public use. In this review, we briefly analyze how the efficacy of liposomes depends on the nature of their components and their size, surface charge, and lipidic organization. Moreover, we discuss the influence of the physicochemical properties of liposomes on their interaction with cells, half-life, ability to enter tissues, and final fate in vivo. Finally, we describe some strategies developed to overcome limitations of the “first-generation” liposomes, and liposome-based drugs on the market and in clinical trials. PMID:25678787

  5. Liposomes for cardiovascular targeting.

    PubMed

    Levchenko, Tatyana S; Hartner, William C; Torchilin, Vladimir P

    2012-04-01

    Liposome-based pharmaceuticals used within the cardiovascular system are reviewed in this article. The delivery of diagnostic and therapeutic agents by plain liposomes and liposomes with surface-attached targeting antibodies or polyethylene glycol to prolong their circulation time and accumulation at vascular injuries, ischemic zones or sites of thrombi are also discussed. An overview of the advantages and disadvantages of liposome-mediated in vitro, ex vivo and in vivo targeting is presented, including discussion of the targeting of liposomes to pathological sites on the blood vessel wall and a description of liposomes that can be internalized by endothelial cells. Diagnostic liposomes used to target myocardial infarction and the relative importance of liposome size, targetability of immunoliposomes and prolonged circulation time on the efficiency of sealing hypoxia-induced plasma membrane damage to cardiocytes are discussed as a promising approach for therapy. The progress in the use of targeted liposomal plasmids for the transfection of hypoxic cardiomyocytes and myocardium is presented. Stent-mediated liposomal-based drug delivery is also reviewed briefly. PMID:22834079

  6. [Electroluminescence character of novel unsymmetry substituted phthalocyanines].

    PubMed

    Xia, Dao-cheng; Li, Wan-cheng; Han, Shuang; Cheng, Chuan-hui; Li, Quan-quan; Wang, Jin; Zhang, Wei; Li, Zhu

    2010-09-01

    The authors for the first time fabricated OLEDs employing novel phthalocynines: 2(3)-(p-tert-butylphenoxy) copper phthalocyanine(1), 2(3),16(17)-di(p-tert-butyl-phenoxy) copper phthalocyanine(2) and 2(3), 9(10), 16(17)-tri (p-tert-butylphenoxy) copper phthalocyanine(3) as light emitting layer, and their electroluminescence character was studied. The final structures of three-layer OLEDs based on copper 2(3)-(p-tert-butylphenoxy) copper phthalocyanine (1) and 2(3), 9(10), 16(17)-tri (p-tert-butylphenoxy) copper phthalocyanine(3) were ITO/NPB(40 nm)/Pc(30 nm)/AlQ(43.5 nm)/LiF (0.5 nm)/Al(120 nm). The structure of three-layer OLED based on 2(3), 9(10), 16(17)-tri (p-tert-butylphenoxy) copper phthalocyanine (3) was ITO/NPB(30 nm)/Pc(30 nm) /BCP(20 nm)/A1Q(30 nm)/LiF (0. 5 nm)/Al(120 nm). Room-temperature electroluminescence was observed at about 869 nmand 1 062 nm for 2(3)-(p-tert-butylphenoxy) copper phthalocyanine(1); room-temperature electroluminescence of 2(3),16(17) -di(p-tert-butyl-phenoxy) copper phthalocyanine(2) was found at about 1050 nm and 1110 nm; and room-temperature electroluminescence of 2(3), 9(10), 16( 17)-tri (p-tert-butylphenoxy) copper phthalocyanine(3) was studied at about 1095 and 1204 nm. The emission wavelengths and the half bandwidths were quite different for the phthalocyanine, which may be due to the differences in the number of substituted and the molecular aggregations in vacuum sublimed films. The difference in Stokes shift relaxation was also induced by the molecular aggregations.

  7. Liposomal formulations for inhalation.

    PubMed

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

    2013-08-01

    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

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

    PubMed

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

    2013-10-01

    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.

  9. Liposomes in investigative dermatology.

    PubMed

    Yarosh, D B

    2001-10-01

    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

  10. Hexacoordinate bonding and aromaticity in silicon phthalocyanine.

    PubMed

    Yang, Yang

    2010-12-23

    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

  11. Adsorption of ammonia on multilayer iron phthalocyanine

    SciTech Connect

    Isvoranu, Cristina; Knudsen, Jan; Ataman, Evren; Andersen, Jesper N.; Schnadt, Joachim; Schulte, Karina; Wang Bin; Bocquet, Marie-Laure

    2011-03-21

    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.

  12. Studies of phthalocyanine-containing polymers

    NASA Astrophysics Data System (ADS)

    Lee, Pui Sze Priscilla

    This thesis reports the synthesis, spectroscopic and photophysical properties, and in vitro photodynamic activities of several series of phthalocyanine-containing polymers including poly(norbornene), poly(anhydride), and poly(epsilon-caprolactone). Chapter 1 gives a general overview of phthalocyanines including their synthesis and applications. Special emphasis has been placed on hydrophilic and non-aggregated phthalocyanines and their use in photodynamic therapy. In addition, different classes of phthalocyanine-containing polymers will also be mentioned. Chapter 2 discusses the synthesis, characterization, and photophysical properties of a series of poly(norbornene)s with zinc(II) phthalocyanine and amino acid moieties. The copolymers were prepared by copolymerization of 2-(2-norbornenylmethoxy)phthalocyaninatozinc(II) with 5-norbornenes substituted with phenylalanine and tyrosine. As shown by absorption and fluorescence spectroscopy, phthalocyanines in this series of polymer exhibit a rather strong aggregation tendency. Chapter 3 presents the synthesis, characterization, photophysical properties, and in vitro photodynamic activities of a related series of amino acid- and sugar-containing poly(norbornene)s connected axially to a silicon(IV) phthalocyanine core. These polymers exhibit a good solubility in common organic solvents. Due to the axial polymeric substituents, these compounds are free from aggregation and give a high singlet oxygen quantum yield. These polymers in Cremophor EL emulsions also show a high photodynamic activity against HepG2 cells, in particular the polymer with protected galactose moieties. Chapter 4 reports a series of silicon(IV) phthalocyanines substituted with two poly(sebacic anhydride) chains as the axial ligands. The polymers form nanoparticles in water in the presence of surfactants cetyltrimethylammonium bromide (CTAB) and sodium dodecylsulphate (SDS). The degradation of the nanoparticles was carried out in alkaline media and was

  13. Liposome behavior in capillary electrophoresis.

    PubMed

    Roberts, M A; Locascio-Brown, L; Maccrehan, W A; Durst, R A

    1996-10-01

    The behavior of liposomes in capillary electrophoresis is studied for the purpose of developing a potential method for characterizing liposomes prepared for use in industrial and analytical applications. This study characterizes the electrophoretic behavior of liposomes under various conditions to provide information about electrophoretic mobility and liposome-capillary surface interactions. The results of this method are compared with the results obtained using traditional laser light-scattering methods to obtain size information about liposome preparations. Additionally, reactions of liposomes and the surfactant n-octyl-β-d-glucopyranoside are performed off-line in bulk solution experiments and on-line in the capillary. Automated delivery of lysis agents by multiple electrokinetic injections is demonstrated as a general method for inducing on-capillary reactions between liposomes and other reagents. Furthermore, some preliminary evidence on the use of liposomes as a hydrophobic partitioning medium for analytical separations is presented.

  14. [Study on spectra properties of novel octa-substituted phthalocyanines].

    PubMed

    Xia, Dao-Cheng; Li, Wan-Cheng; Wang, Hong-Fu; Zheng, Xin-Xing; Guo, Yan-Jie; Yang, Xu-Qing

    2011-08-01

    The spectrum properties of four novel 1, 4, 8, 11, 15, 18, 22, 25-octaoxybutyl copper phthalocyanine; 1,4,8,11,15,18, 22, 25-octamethoxybutanoate manganese phthalocyanine; 1, 4, 8, 11, 15, 18, 22, 25-octamethoxybutanoate copper phthalocyanine; 1, 4, 8, 11, 15, 18, 22, 25-octamethoxybutanoate zinc phthalocyanine were investigated by infrared, fluorescence and UV-visible spectrum in the the paper. There is no rule in the infrared spectrum of these octa-substituted phthalocyanines. The orders of the Q band, B band and Pc dimer band are different among the above Octa-substituted Phthalocyanines in the UV and fluorescence spectra. The reason is related to the interaction between the ligand and the central metal of these octa-substituted phthalocyanines.

  15. Liposomes in silicosis investigations.

    PubMed

    Erdogdu, G; Hasirci, V N

    1983-09-01

    The effects of quartz and sodium metasilicate on liposomes were studied in order to understand the mechanism of silicosis. 8-Hydroxyquinoline-5-sulfonic acid was tested for its in situ silicosis-prevention capacity. Two types of liposomes--(A) those incorporating cholesterol and (B) those without cholesterol--were used. The tests consisted of measuring permeability changes caused by the above-mentioned chemicals. Permeabilities were found to depend on membrane composition. Tests on quartz action led us to the conclusion that liposomes of this composition did not simulate the erythrocytes very well. It was also observed that absence or presence of cholesterol and the mode of contact altered the effect of quartz. Silicate destabilized type A liposomes, but this was less than that caused by quartz. This was explained by the concentration of monosilicic acid that dissolves out from quartz and silicate. When quartz was pretreated with the preventive, the type A liposomes were stabilized, but a slight destabilizing effect was observed on type B. 8-Hydroxyquinoline-5-sulfonic acid augmented the destabilizing effect of silicate, whereas it decreased the hemolytic activity of uncoated quartz, indicating a preventive potential in in vivo.

  16. Liposomes in silicosis investigations.

    PubMed Central

    Erdogdu, G; Hasirci, V N

    1983-01-01

    The effects of quartz and sodium metasilicate on liposomes were studied in order to understand the mechanism of silicosis. 8-Hydroxyquinoline-5-sulfonic acid was tested for its in situ silicosis-prevention capacity. Two types of liposomes--(A) those incorporating cholesterol and (B) those without cholesterol--were used. The tests consisted of measuring permeability changes caused by the above-mentioned chemicals. Permeabilities were found to depend on membrane composition. Tests on quartz action led us to the conclusion that liposomes of this composition did not simulate the erythrocytes very well. It was also observed that absence or presence of cholesterol and the mode of contact altered the effect of quartz. Silicate destabilized type A liposomes, but this was less than that caused by quartz. This was explained by the concentration of monosilicic acid that dissolves out from quartz and silicate. When quartz was pretreated with the preventive, the type A liposomes were stabilized, but a slight destabilizing effect was observed on type B. 8-Hydroxyquinoline-5-sulfonic acid augmented the destabilizing effect of silicate, whereas it decreased the hemolytic activity of uncoated quartz, indicating a preventive potential in in vivo. Images FIGURE 1. PMID:6416823

  17. Viscoelasticity measurements inside liposomes

    NASA Astrophysics Data System (ADS)

    Zhang, Shu; Gibson, Lachlan; Preece, Daryl; Nieminen, Timo A.; Rubinsztein-Dunlop, Halina

    2014-09-01

    Microrheology, the study of the behavior of fluids on the microscopic scale, has been and continues to be one of the most important subjects that can be applied to characterize the behavior of biological fluids. It is extremely difficult to make rapid measurement of the viscoelastic properties of the interior of living cells. Liposomes are widely used as model system for studying different aspects of cell biology. We propose to develop a microrheometer, based on real-time control of optical tweezers, in order to investigate the viscoelastic properties of the fluid inside liposomes. This will give greater understanding of the viscoelastic properties of the fluids inside cells. In our experiment, the liposomes are prepared by different methods to find out both a better way to make GUVs and achieve efficient encapsulation of particle. By rotating the vaterite inside a liposome via spin angular momentum, the optical torque can be measured by measuring the change of polarization of the transmitted light, which allows the direct measurement of viscous drag torque since the optical torque is balanced by the viscous drag. We present an initial feasibility demonstration of trapping and manipulation of a microscopic vaterite inside the liposome. The applied method is simple and can be extended to sensing within the living cells.

  18. Two-photon excitation of aluminium phthalocyanines

    SciTech Connect

    Meshalkin, Yu P; Alfimov, E E; Makukha, V K; Vasil'ev, N E; Denisov, A N; Ogirenko, A P

    1999-12-31

    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)

  19. DNA-binding and oxidative properties of cationic phthalocyanines and their dimeric complexes with anionic phthalocyanines covalently linked to oligonucleotides.

    PubMed

    Kuznetsova, A A; Lukyanets, E A; Solovyeva, L I; Knorre, D G; Fedorova, O S

    2008-12-01

    Design of chemically modified oligonucleotides for regulation of gene expression has attracted considerable attention over the past decades. One actively pursued approach involves antisense or antigene oligonucleotide constructs carrying reactive groups, many of these based on transition metal complexes. The complexes of Fe(II) and Co(II) with phthalocyanines are extremely good catalysts of oxidation of organic compounds with molecular oxygen and hydrogen peroxide. The binding of positively charged Fe(II) and Co(II) phthalocyanines with single- and double-stranded DNA was investigated. It was shown that these phthalocyanines interact with nucleic acids through an outside binding mode. The site-directed modification of single-stranded DNA by O2 and H2O2 in the presence of dimeric complexes of negatively and positively charged Fe(II) and Co(II) phthalocyanines was investigated. These complexes were formed directly on single-stranded DNA through interaction between negatively charged phthalocyanine in conjugate and positively charged phthalocyanine in solution. The resulting oppositely charged phthalocyanine complexes showed significant increase of catalytic activity compared with monomeric forms of phthalocyanines Fe(II) and Co(II). These complexes catalyzed the DNA oxidation with high efficacy and led to direct DNA strand cleavage. It was determined that oxidation of DNA by molecular oxygen catalyzed by complex of Fe(II)-phthalocyanines proceeds with higher rate than in the case of Co(II)-phthalocyanines but the latter led to a greater extent of target DNA modification.

  20. [Photophysical properties and photodynamic activity of nanostructured aluminium phthalocyanines].

    PubMed

    Udartseva, O O; Lobanov, A V; Andeeva, E R; Dmitrieva, G S; Mel'nikov, M Ia; Buravkova, L B

    2014-01-01

    We developed water-soluble supramolecular complexes of aluminium phthalocyanine based on mesoporous silica nanoparticles and polyvinylpirrolidone containing rare photoactive nanoaggregates. Radiative lifetimes, extinction coefficients and energy of electronic transitions of isolated and associated metal phthalocyanine complexes were calculated. Nontoxic concentrations of synthesized nanocomposite photosensibilizers were in vitro determined. In present study we compared photodynamic treatment efficacy using different modifications of aluminium phthalocyanine (Photosens®, AlPc-nSiO2 and AlPc-PVP). Mesenchymal stromal cells were used as a model for photodynamic treatment. Intracellular accumulation of aluminium phthalocyanine based on mesoporous silica nanoparticles AlPc-nSiO2 was the most efficient. Illumination of phthalocyanine-loaded cells led to reactive oxygen species generation and subsequent apoptotic cell death. Silica nanoparticles provided a significant decrease of effective phthalocyanine concentration and enhanced cytotoxicity of photodynamic treatment.

  1. Liposomes: Technologies and Analytical Applications

    NASA Astrophysics Data System (ADS)

    Jesorka, Aldo; Orwar, Owe

    2008-07-01

    Liposomes are structurally and functionally some of the most versatile supramolecular assemblies in existence. Since the beginning of active research on lipid vesicles in 1965, the field has progressed enormously and applications are well established in several areas, such as drug and gene delivery. In the analytical sciences, liposomes serve a dual purpose: Either they are analytes, typically in quality-assessment procedures of liposome preparations, or they are functional components in a variety of new analytical systems. Liposome immunoassays, for example, benefit greatly from the amplification provided by encapsulated markers, and nanotube-interconnected liposome networks have emerged as ultrasmall-scale analytical devices. This review provides information about new developments in some of the most actively researched liposome-related topics.

  2. Boronated liposome development and evaluation

    SciTech Connect

    Hawthorne, M.F.

    1995-11-01

    The boronated liposome development and evaluation effort consists of two separate tasks. The first is the development of new boron compounds and the synthesis of known boron species with BNCT potential. These compounds are then encapsulated within liposomes for the second task, biodistribution testing in tumor-bearing mice, which examines the potential for the liposomes and their contents to concentrate boron in cancerous tissues.

  3. Hydrophobicity, topography in membranes and photosensitization of silicon phthalocyanines with axial ligands of varying lengths.

    PubMed

    Sholto, Alan; Ehrenberg, Benjamin

    2008-03-01

    Six amphiphilic silicon phthalocyanines (SiPc's) axially linked to a dimethylated amino alkyl group of varying length have been examined for their potential suitability as photosensitizers for photodynamic therapy (PDT). This group of molecules was chosen because the length of the axial ligand might place the chromophoric part of the molecule at different vertical depths in the membrane and possibly affect the extent of membrane localized damage caused by singlet oxygen. We tested the relative penetration depth of the SiPc groups in the membrane by the extent to which their fluorescence was quenched by external iodide ions. We also measured singlet oxygen quantum yields of the SiPc's in a liposome membrane, using the fluorescent target for singlet oxygen, 9,10-dimethylanthracene. The hydrophobicity parameters, LogP, were calculated and were also measured. Some correlation was found between them and Kb's, the binding constants for liposomes. The effect of the axial ligand's length is less striking than in similar cases with hematoporphyrins and protoporphyrins. We link this smaller effect with a bending of the linker chain that enables, sterically, a better positioning of the sensitizer molecules within the ordered lipid layer structure.

  4. Ligation Strategies for Targeting Liposomal Nanocarriers

    PubMed Central

    Marqués-Gallego, Patricia; de Kroon, Anton I. P. M.

    2014-01-01

    Liposomes have been exploited for pharmaceutical purposes, including diagnostic imaging and drug and gene delivery. The versatility of liposomes as drug carriers has been demonstrated by a variety of clinically approved formulations. Since liposomes were first reported, research of liposomal formulations has progressed to produce improved delivery systems. One example of this progress is stealth liposomes, so called because they are equipped with a PEGylated coating of the liposome bilayer, leading to prolonged blood circulation and improved biodistribution of the liposomal carrier. A growing research area focuses on the preparation of liposomes with the ability of targeting specific tissues. Several strategies to prepare liposomes with active targeting ligands have been developed over the last decades. Herein, several strategies for the functionalization of liposomes are concisely summarized, with emphasis on recently developed technologies for the covalent conjugation of targeting ligands to liposomes. PMID:25126543

  5. Lighting porphyrins and phthalocyanines for molecular photovoltaics.

    PubMed

    Martínez-Díaz, M Victoria; de la Torre, Gema; Torres, Tomás

    2010-10-14

    The field of organic photovoltaics (OPV) represents one of the most promising technological areas. Porphyrins and phthalocyanines are perfectly suited for their integration in light energy conversion systems. These colored macrocycles exhibit very attractive physical properties, particularly very high extinction coefficients in the visible and near IR regions, where the maximum of the solar photon flux occurs, that is necessary for efficient photon harvesting, besides a rich redox chemistry, as well as photoinduced electron transfer and semiconducting capabilities.

  6. Monodisperse Uni- and Multicompartment Liposomes.

    PubMed

    Deng, Nan-Nan; Yelleswarapu, Maaruthy; Huck, Wilhelm T S

    2016-06-22

    Liposomes are self-assembled phospholipid vesicles with great potential in fields ranging from targeted drug delivery to artificial cells. The formation of liposomes using microfluidic techniques has seen considerable progress, but the liposomes formation process itself has not been studied in great detail. As a result, high throughput, high-yielding routes to monodisperse liposomes with multiple compartments have not been demonstrated. Here, we report on a surfactant-assisted microfluidic route to uniform, single bilayer liposomes, ranging from 25 to 190 μm, and with or without multiple inner compartments. The key of our method is the precise control over the developing interfacial energies of complex W/O/W emulsion systems during liposome formation, which is achieved via an additional surfactant in the outer water phase. The liposomes consist of single bilayers, as demonstrated by nanopore formation experiments and confocal fluorescence microscopy, and they can act as compartments for cell-free gene expression. The microfluidic technique can be expanded to create liposomes with a multitude of coupled compartments, opening routes to networks of multistep microreactors. PMID:27243596

  7. Liposome: classification, preparation, and applications

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

    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.

  8. Vacuum synthesis of magnetic aluminum phthalocyanine on Au(111).

    PubMed

    Hong, I-Po; Li, Na; Zhang, Ya-Jie; Wang, Hao; Song, Huan-Jun; Bai, Mei-Lin; Zhou, Xiong; Li, Jian-Long; Gu, Gao-Chen; Zhang, Xue; Chen, Min; Gottfried, J Michael; Wang, Dong; Lü, Jing-Tao; Peng, Lian-Mao; Hou, Shi-Min; Berndt, Richard; Wu, Kai; Wang, Yong-Feng

    2016-08-16

    Air-unstable magnetic aluminum phthalocyanine (AlPc) molecules are prepared by an on-surface metalation reaction of phthalocyanine with aluminum (Al) atoms on Au(111) in ultrahigh vacuum. Experiments and density functional theory calculations show that an unpaired spin is located on the conjugated isoindole lobes of the molecule rather than at the Al position. PMID:27406881

  9. Improvement of power conversion efficiency of phthalocyanine/C60 heterojunction solar cells by inserting a lithium phthalocyanine layer at the indium-tin oxide/phthalocyanine interface

    NASA Astrophysics Data System (ADS)

    Tanaka, Senku; Hanada, Toshiyuki; Ono, Koji; Watanabe, Kazuya; Yoshino, Katsumi; Hiromitsu, Ichiro

    2010-12-01

    Improvement of power conversion efficiency of a zinc phthalocyanine (ZnPc)/C60 heterojunction solar cell was achieved by inserting a lithium phthalocyanine (LiPc) layer at the indium-tin oxide (ITO)/ZnPc interface. The results of photoelectron spectroscopy suggest that the barrier height for the hole transport at the ITO/ZnPc interface is reduced by the LiPc layer. A similar improvement of the power conversion efficiency by the insertion of a LiPc layer was also observed in M-phthalocyanine (M=H2, Cu, and TiO)/C60 cells.

  10. Room temperature ferromagnetism in a phthalocyanine based carbon material

    SciTech Connect

    Honda, Z. Sato, K.; Sakai, M.; Fukuda, T.; Kamata, N.; Hagiwara, M.; Kida, T.

    2014-02-07

    We report on a simple method to fabricate a magnetic carbon material that contains nitrogen-coordinated transition metals and has a large magnetic moment. Highly chlorinated iron phthalocyanine was used as building blocks and potassium as a coupling reagent to uniformly disperse nitrogen-coordinated iron atoms on the phthalocyanine based carbon material. The iron phthalocyanine based carbon material exhibits ferromagnetic properties at room temperature and the ferromagnetic phase transition occurs at T{sub c} = 490 ± 10 K. Transmission electron microscopy observation, X-ray diffraction analysis, and the temperature dependence of magnetization suggest that the phthalocyanine molecules form three-dimensional random networks in the iron phthalocyanine based carbon material.

  11. Liposome: classification, preparation, and applications

    PubMed Central

    2013-01-01

    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. PMID:23432972

  12. Biological activity of liposomal vanillin.

    PubMed

    Castan, Leniher; Del Toro, Grisel; Fernández, Adolfo A; González, Manuel; Ortíz, Emilia; Lobo, Daliana

    2013-06-01

    This article presents a study of vanillin encapsulation inside multilamellar liposomes, with emphasis on the evaluation of antioxidant activity, the hemolytic effect, and the antisickling properties of these products. Egg phosphatidylcholine-cholesterol and egg phosphatidylcholine-cholesterol-1-O-decylglycerol liposomes were prepared by mechanical dispersion, all with vanillin included. Vesicles were characterized by determination of encapsulation efficiency and vanillin retention capacity. Antioxidant activity was determined by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) method. The hemolytic effect of liposomes was also evaluated by spectrophotometry, as well as the antisickling activity by the Huck test using optical microscopy. Results showed that the lipid composition of liposomes did not significantly affect the encapsulation efficiency. Stable vesicles were obtained with a high retention percentage of vanillin. Liposomes exhibited a high capture of the DPPH radical compared to free vanillin and 1-O-decylglycerol (C10) in solution. Vesicles caused no significant hemolisys in normal erythrocytes, nor in those coming from patients with sickle cell anemia. Vanillin encapsulated in liposomes retained its antisickling activity, with a greater effect for C10-containing vesicles. Our results show that vanillin encapsulation in liposomes is a way to enhance the pharmacologic properties of this molecule using a suitable vehicle.

  13. Liposome Technology for Industrial Purposes

    PubMed Central

    Wagner, Andreas; Vorauer-Uhl, Karola

    2011-01-01

    Liposomes, spherical vesicles consisting of one or more phospholipid bilayers, were first described in the mid 60s by Bangham and coworkers. Since then, liposomes have made their way to the market. Today, numerous lab scale but only a few large-scale techniques are available. However, a lot of these methods have serious limitations in terms of entrapment of sensitive molecules due to their exposure to mechanical and/or chemical stress. This paper summarizes exclusively scalable techniques and focuses on strengths, respectively, limitations in respect to industrial applicability. An additional point of view was taken to regulatory requirements concerning liposomal drug formulations based on FDA and EMEA documents. PMID:21490754

  14. Photophysical and theoretical investigations on fullerene/phthalocyanine supramolecular complexes.

    PubMed

    Ray, Anamika; Goswami, Dibakar; Chattopadhyay, Subrata; Bhattacharya, Sumanta

    2008-11-20

    The present paper reports the photophysical aspects of a very interesting and unique host-guest interaction between fullerene and phthalocyanines, viz., free base phthalocyanine (H2-Pc) and zinc-phthalocyanine (Zn-Pc), in toluene medium. Ground state electronic interaction between these two supramolecules has been evidenced from the observation of well-defined charge transfer (CT) absorption bands in the visible region. Vertical ionization potentials of the phthalocyanines have been determined utilizing CT transition energy. Magnitude of degrees of CT reveals that, in the ground state, 2-4% CT takes place. Binding constants (K) for the fullerene/phthalocyanine complexes were determined from the fluorescence quenching experiment. Large K values in the ranges approximately 4.7 x 10(4) to 7.3 x 10(4) and 2.3 x 10(4) to 2.5 x 10(4) dm(3) x mol(-1) were obtained for the 1:1 fullerene complexes of Zn and H 2-Pc, respectively. Values of K suggest that both H 2- and Zn-Pc could not serve as an efficient discriminators between C60 and C70. Theoretical calculations as well as (13)C NMR studies establish that the orientation of C 70 toward phthalocyanine is favored in end-on orientation, which proves that interaction between fullerenes and phthalocyanines were governed by the electrostatic mechanism rather than dispersive forces associated with pi-pi interaction.

  15. Novel axially disubstituted non-aggregated silicon phthalocyanines

    NASA Astrophysics Data System (ADS)

    Bıyıklıoğlu, Zekeriya; Çakır, Dilek

    2012-12-01

    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.

  16. Novel axially disubstituted non-aggregated silicon phthalocyanines.

    PubMed

    Bıyıklıoğlu, Zekeriya; Cakır, Dilek

    2012-12-01

    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, (1)H NMR, (13)C NMR spectroscopy, ESI mass spectrometry. These new silicon(IV) phthalocyanines 3 and 5 showed excellent solubility in organic solvents such as CHCl(3), CH(2)Cl(2), 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.

  17. Controlling Growth Orientation of Phthalocyanine Films by Electrical Fields

    NASA Technical Reports Server (NTRS)

    Zhu, S.; Banks, C. E.; Frazier, D. O.; Ila, D.; Muntele, I.; Penn, B. G.; Sharma, A.; Rose, M. Franklin (Technical Monitor)

    2001-01-01

    Organic Phthalocyanine films have many applications ranging from data storage to various non-linear optical devices whose quality is affected by the growth orientation of Phthalocyanine films. Due to the structural and electrical properties of Phthalocyanine molecules, the film growth orientation depends strongly on the substrate surface states. In this presentation, an electrical field up to 4000 V/cm is introduced during film growth. The Phthalocyanine films are synthesized on quartz substrates using thermal evaporation. An intermediate layer is deposited on some substrates for introducing the electrical field. Scanning electron microscopy, x-ray diffraction, and Fourier transform infrared spectroscopy are used for measuring surface morphology, film structure, and optical properties, respectively. The comparison of Phthalocyanine films grown with and without the electrical field reveals different morphology, film density, and growth orientation, which eventually change optical properties of these films. These results suggest that the growth method in the electrical field can be used to synthesized Phthalocyanine films with a preferred crystal orientation as well as propose an interaction mechanism between the substrate surface and the depositing molecules. The details of growth conditions and of the growth model of how the Phthalocyanine molecules grow in the electrical field will be discussed.

  18. Optically Active Porphyrin and Phthalocyanine Systems.

    PubMed

    Lu, Hua; Kobayashi, Nagao

    2016-05-25

    This review highlights and summarizes various optically active porphyrin and phthalocyanine molecules prepared using a wide range of structural modification methods to improve the design of novel structures and their applications. The induced chirality of some illustrative achiral bis-porphyrins with a chiral guest molecule is introduced because these systems are ideal for the identification and separation of chiral biologically active substrates. In addition, the relationship between CD signal and the absolute configuration of the molecule is analyzed through an analysis of the results of molecular modeling calculations. Possible future research directions are also discussed. PMID:27186902

  19. Hesperetin Liposomes for Cancer Therapy.

    PubMed

    Wolfram, Joy; Scott, Bronwyn; Boom, Kathryn; Shen, Jianliang; Borsoi, Carlotta; Suri, Krishna; Grande, Rossella; Fresta, Massimo; Celia, Christian; Zhao, Yuliang; Shen, Haifa; Ferrari, Mauro

    2016-01-01

    Hesperetin is a compound from citrus fruit that has previously been found to exert anticancer activity through a variety of mechanisms. However, the application of hesperetin to cancer therapy has been hampered by its hydrophobicity, necessitating the use of toxic solubilizing agents. Here, we have developed the first liposome-based delivery system for hesperetin. Liposomes were fabricated using the thin-layer evaporation technique and physical and pharmacological parameters were measured. The liposomes remained stable for prolonged periods of time in serum and under storage conditions, and displayed anticancer efficacy in both H441 lung cancer cells and MDA-MB-231 breast cancer cells. Furthermore, the anticancer activity was not impaired in cells expressing the multidrug resistance protein 1 (MDR-1). In conclusion, the encapsulation of hesperetin in liposomes does not interfere with therapeutic efficacy and provides a biocompatible alternative to toxic solubilizing agents, thereby enabling future clinical use of this compound for cancer therapy.

  20. 99m tc labeled liposomes

    SciTech Connect

    Phillips, W.T.; Klipper, R.W.; Timmons, J.H.; Rudolph, A.S.

    1992-10-27

    This patent describes a method of preparing stable gamma-emitting radionuclide-labeled alkyleneamine oxime, the incubating being for a period of time sufficient to form labeled liposome-encapsulated protein.

  1. Phospholipid liposomes functionalized by protein

    NASA Astrophysics Data System (ADS)

    Glukhova, O. E.; Savostyanov, G. V.; Grishina, O. A.

    2015-03-01

    Finding new ways to deliver neurotrophic drugs to the brain in newborns is one of the contemporary problems of medicine and pharmaceutical industry. Modern researches in this field indicate the promising prospects of supramolecular transport systems for targeted drug delivery to the brain which can overcome the blood-brain barrier (BBB). Thus, the solution of this problem is actual not only for medicine, but also for society as a whole because it determines the health of future generations. Phospholipid liposomes due to combination of lipo- and hydrophilic properties are considered as the main future objects in medicine for drug delivery through the BBB as well as increasing their bioavailability and toxicity. Liposomes functionalized by various proteins were used as transport systems for ease of liposomes use. Designing of modification oligosaccharide of liposomes surface is promising in the last decade because it enables the delivery of liposomes to specific receptor of human cells by selecting ligand and it is widely used in pharmacology for the treatment of several diseases. The purpose of this work is creation of a coarse-grained model of bilayer of phospholipid liposomes, functionalized by specific to the structural elements of the BBB proteins, as well as prediction of the most favorable orientation and position of the molecules in the generated complex by methods of molecular docking for the formation of the structure. Investigation of activity of the ligand molecule to protein receptor of human cells by the methods of molecular dynamics was carried out.

  2. Liposomes in biology and medicine.

    PubMed

    Schwendener, Reto A

    2007-01-01

    Drug delivery systems (DDS) have become important tools for the specific delivery of a large number of drug molecules. Since their discovery in the 1960s liposomes were recognized as models to study biological membranes and as versatile DDS of both hydrophilic and lipophilic molecules. Liposomes--nanosized unilamellar phospholipid bilayer vesicles--undoubtedly represent the most extensively studied and advanced drug delivery vehicles. After a long period of research and development efforts, liposome-formulated drugs have now entered the clinics to treat cancer and systemic or local fungal infections, mainly because they are biologically inert and biocompatible and practically do not cause unwanted toxic or antigenic reactions. A novel, up-coming and promising therapy approach for the treatment of solid tumors is the depletion of macrophages, particularly tumor associated macrophages with bisphosphonate-containing liposomes. In the advent of the use of genetic material as therapeutic molecules the development of delivery systems to target such novel drug molecules to cells or to target organs becomes increasingly important. Liposomes, in particular lipid-DNA complexes termed lipoplexes, compete successfully with viral gene transfection systems in this field of application. Future DDS will mostly be based on protein, peptide and DNA therapeutics and their next generation analogs and derivatives. Due to their versatility and vast body of known properties liposome-based formulations will continue to occupy a leading role among the large selection of emerging DDS.

  3. Liposomal nanocarriers for plasminogen activators.

    PubMed

    Koudelka, Stepan; Mikulik, Robert; Mašek, Josef; Raška, Milan; Turánek Knotigová, Pavlína; Miller, Andrew D; Turánek, Jaroslav

    2016-04-10

    Several plasminogen activators (PAs) have been found effective in treating different thromboembolic diseases. However, administration of conventional thrombolytic therapy is limited by a low efficacy of present formulations of PAs. Conventional treatments using these therapeutic proteins are associated with several limitations including rapid inactivation and clearance, short half-life, bleeding complications or non-specific tissue targeting. Liposome-based formulations of PAs such as streptokinase, tissue-plasminogen activator and urokinase have been developed to improve the therapeutic efficacy of these proteins. Resulting liposomal formulations were found to preserve the original activity of PAs, promote their selective delivery and improve thrombus targeting. Therapeutic potential of these liposome-based PAs has been demonstrated successfully in various pre-clinical models in vivo. Reductions in unwanted side effects (e.g., hemorrhage or immunogenicity) as well as enhancements of efficacy and safety were achieved in comparison to currently existing treatment options based on conventional formulations of PAs. This review summarizes present achievements in: (i) preparation of liposome-based formulations of various PAs, (ii) development of PEGylated and targeted liposomal PAs, (iii) physico-chemical characterization of these developed systems, and (iv) testing of their thrombolytic efficacy. We also look to the future and the imminent arrival of theranostic liposomal formulations to move this field forward. PMID:26876783

  4. Stabilization of enzymes through encapsulation in liposomes.

    PubMed

    Yoshimoto, Makoto

    2011-01-01

    Phospholipid vesicle (liposome) offers an aqueous compartment surrounded by lipid bilayer membranes. Various enzyme molecules were reported to be encapsulated in liposomes. The liposomal enzyme shows peculiar catalytic activity and selectivity to the substrate in the bulk liquid, which are predominantly derived from the substrate permeation resistance through the membrane. We reported that the quaternary structure of bovine liver catalase and alcohol dehydrogenase was stabilized in liposomes through their interaction with lipid membranes. The method and condition for preparing the enzyme-containing liposomes with well-defined size, lipid composition, and enzyme content are of particular importance, because these properties dominate the catalytic performance and stability of the liposomal enzymes. PMID:20865384

  5. The antioxidant properties of different phthalocyanines.

    PubMed

    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

    2012-02-01

    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

  6. Unsymmetrical pyrene-fused phthalocyanine derivatives: synthesis, structure, and properties.

    PubMed

    Pan, Houhe; Chen, Chao; Wang, Kang; Li, Wenjun; Jiang, Jianzhuang

    2015-02-16

    Novel pyrene-fused unsymmetrical phthalocyanine derivatives 2,3,9,10,16,17-hexakis(2,6-dimethylphenoxy)-22,25-diaza(2,7-di-tert-butylpyrene)[4,5]phthalocyaninato zinc complex Zn[Pc(Pz-pyrene)(OC8 H9 )6 ] (1) and 2,3,9,10-tra(2,6-dimethylphenoxy)-15,18,22,25-traza(2,7-di-tert-butylpyrene)[4,5]phthalocyaninato zinc compound Zn[Pc(Pz-pyrene)2 (OC8 H9 )4 ] (2) were isolated for the first time. These unsymmetrical pyrene-fused phthalocyanine derivatives have been characterized by a wide range of spectroscopic and electrochemical methods. In particular, the pyrene-fused phthalocyanine structure was unambiguously revealed on the basis of single crystal X-ray diffraction analysis of 1, representing the first structurally characterized phthalocyanine derivative fused with an aromatic moiety larger than benzene.

  7. Uranyl phthalocyanines show promise in the treatment of brain tumors

    NASA Technical Reports Server (NTRS)

    Frigerio, N. A.

    1967-01-01

    Processes synthesize sulfonated and nonsulfonated uranyl phthalocyanines for application in neutron therapy of brain tumors. Tests indicate that the compounds are advantageous over the previously used boron and lithium compounds.

  8. Enhancement of ultrasonically induced cell damage by phthalocyanines in vitro.

    PubMed

    Milowska, Katarzyna; Gabryelak, Teresa

    2008-12-01

    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.

  9. Soluble phthalocyanine silicone plastics and elastomers for nonlinear optics

    NASA Astrophysics Data System (ADS)

    Dirk, Carl W.; Bao, Jiemin; Kuzyk, Mark G.; Poga, Constantina

    1994-09-01

    We present a procedure for trivially preparing soluble, spinnable phthalocyanine plastics and elastomers containing high concentrations of silicon phthalocyanine incorporated as a copolymer. Polymers prepared by this method can easily be fashioned as thin films for optoelectronic applications. We present a visible broad band quadratic electroabsorption measurement on one such thin film, providing the real and imaginary components of (gamma) as well as the figure of merit Re[(gamma) ]/Im[(alpha) ].

  10. Modelling copper-phthalocyanine/cobalt-phthalocyanine chains: towards magnetic quantum metamaterials.

    PubMed

    Wu, Wei

    2014-07-23

    The magnetic properties of a theoretically designed molecular chain structure CuCoPc2, in which copper-phthalocyanine (CuPc) and cobalt-phthalocyanine (CoPc) alternate, have been investigated across a range of chain structures. The computed exchange interaction for the α-phase CuCoPc2 is ∼ 5 K (ferromagnetic), in strong contrast to the anti-ferromagnetic interaction recently observed in CuPc and CoPc. The computed exchange interactions are strongly dependent on the stacking angle but weakly on the sliding angle, and peak at 20 K (ferromagnetic). These ferromagnetic interactions are expected to arise from direct exchange with the strong suppression of super-exchange interaction. These first-principles calculations show that π-conjugated molecules, such as phthalocyanine, could be used as building blocks for the design of magnetic materials. This therefore extends the concept of quantum metamaterials further into magnetism. The resulting new magnetic materials could find applications in the studies such as organic spintronics.

  11. Modelling copper-phthalocyanine/cobalt-phthalocyanine chains: towards magnetic quantum metamaterials.

    PubMed

    Wu, Wei

    2014-07-23

    The magnetic properties of a theoretically designed molecular chain structure CuCoPc2, in which copper-phthalocyanine (CuPc) and cobalt-phthalocyanine (CoPc) alternate, have been investigated across a range of chain structures. The computed exchange interaction for the α-phase CuCoPc2 is ∼ 5 K (ferromagnetic), in strong contrast to the anti-ferromagnetic interaction recently observed in CuPc and CoPc. The computed exchange interactions are strongly dependent on the stacking angle but weakly on the sliding angle, and peak at 20 K (ferromagnetic). These ferromagnetic interactions are expected to arise from direct exchange with the strong suppression of super-exchange interaction. These first-principles calculations show that π-conjugated molecules, such as phthalocyanine, could be used as building blocks for the design of magnetic materials. This therefore extends the concept of quantum metamaterials further into magnetism. The resulting new magnetic materials could find applications in the studies such as organic spintronics. PMID:24990182

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

    PubMed Central

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

    2011-01-01

    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. PMID:21928859

  13. Synthesis and photophysical studies of phthalocyanine-gold nanoparticle conjugates.

    PubMed

    Nombona, Nolwazi; Antunes, Edith; Litwinski, Christian; Nyokong, Tebello

    2011-11-28

    This work reports on the synthesis, characterization and photophysical studies of phthalocyanine-gold nanoparticle conjugates. The phthalocyanine complexes are: tris-(5-trifluoromethyl-2-mercaptopyridine)-2-(carboxy)phthalocyanine (3), 2,9,17,23-tetrakis-[(1, 6-hexanedithiol) phthalocyaninato]zinc(II) (8) and [8,15,22-tris-(naptho)-2(amidoethanethiol) phthalocyanato] zinc(II)(10). The gold nanoparticles were characterized using transmission electron microscopy, X-ray diffraction, atomic force microscopy and UV-vis spectroscopy where the size was confirmed to be ∼5 nm. The phthalocyanine Au nanoparticle conjugates showed lower fluorescence quantum yield values with similar fluorescence lifetimes compared to the free phthalocyanines. The Au nanoparticle conjugates of 3 and 10 also showed higher triplet quantum yields of 0.69 to 0.71, respectively. A lower triplet quantum yield was obtained for the conjugate compared to free phthalocyanine for complex 8. The triplet lifetimes ranged from 70 to 92 μs for the conjugates and from 110 to 304 μs for unbound Pc complexes.

  14. Photophysical studies of newly derivatized mono substituted phthalocyanines grafted onto silica nanoparticles via click chemistry.

    PubMed

    Fashina, Adedayo; Amuhaya, Edith; Nyokong, Tebello

    2015-04-01

    This work reports on the synthesis, characterization and photophysical studies of newly derived phthalocyanine complexes and the phthalocyanine-silica nanoparticles conjugates. The derived phthalocyanine complexes have one terminal alkyne group. The derived phthalocyanine complexes showed improved photophysical properties (ФF, ФT, ΦΔ and τT) compared to the respective phthalocyanine complexes from which they were derived. The derived phthalocyanine complexes were conjugated to the surface of an azide functionalized silica nanoparticles via copper (1) catalyzed cyclo-addition reaction. All the conjugates showed lower triplet quantum yields ranging from 0.37 to 0.44 compared to the free phthalocyanine complexes. The triplet lifetimes ranged from 352 to 484 μs for the conjugates and from 341 to 366 μs for the free phthalocyanine complexes.

  15. Intramolecular aggregation and optical limiting properties of triazine-linked mono-, bis- and tris-phthalocyanines.

    PubMed

    Chen, Jun; Zhang, Tao; Wang, Shuangqing; Hu, Rui; Li, Shayu; Ma, Jin Shi; Yang, Guoqiang

    2015-10-01

    A series of triazine-linked mono-, bis- and tris-phthalocyanines are synthesized, intramolecular aggregation is found in bis- and tris-phthalocyanines via π-π stacking interaction. Theoretical and experimental studies reveal the formation of the intramolecular aggregation. The spectrographic, photophysical and nonlinear optical properties of these compounds are adjusted for the formation of the intramolecular aggregation. The bis-phthalocyanine dimer presents smaller fluorescence quantum yield, lower triplet formation yield and the triplet-minus-ground state extinction coefficient, which causes poorer optical limiting performance. It is interesting that the tris-phthalocyanine is composed of a mono-phthalocyanine part and a bis-phthalocyanine part, the optical limiting property of the tris-phthalocyanine is similar to that of mono-phthalocyanine.

  16. Photophysical studies of newly derivatized mono substituted phthalocyanines grafted onto silica nanoparticles via click chemistry.

    PubMed

    Fashina, Adedayo; Amuhaya, Edith; Nyokong, Tebello

    2015-04-01

    This work reports on the synthesis, characterization and photophysical studies of newly derived phthalocyanine complexes and the phthalocyanine-silica nanoparticles conjugates. The derived phthalocyanine complexes have one terminal alkyne group. The derived phthalocyanine complexes showed improved photophysical properties (ФF, ФT, ΦΔ and τT) compared to the respective phthalocyanine complexes from which they were derived. The derived phthalocyanine complexes were conjugated to the surface of an azide functionalized silica nanoparticles via copper (1) catalyzed cyclo-addition reaction. All the conjugates showed lower triplet quantum yields ranging from 0.37 to 0.44 compared to the free phthalocyanine complexes. The triplet lifetimes ranged from 352 to 484 μs for the conjugates and from 341 to 366 μs for the free phthalocyanine complexes. PMID:25615674

  17. Vibrational studies of molecular organization in evaporated phthalocyanine thin solid films

    SciTech Connect

    Aroca, R.; Thedchanamoorthy, A.

    1995-01-01

    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.

  18. Photophysical studies of newly derivatized mono substituted phthalocyanines grafted onto silica nanoparticles via click chemistry

    NASA Astrophysics Data System (ADS)

    Fashina, Adedayo; Amuhaya, Edith; Nyokong, Tebello

    2015-04-01

    This work reports on the synthesis, characterization and photophysical studies of newly derived phthalocyanine complexes and the phthalocyanine-silica nanoparticles conjugates. The derived phthalocyanine complexes have one terminal alkyne group. The derived phthalocyanine complexes showed improved photophysical properties (ФF, ФT, ΦΔ and τT) compared to the respective phthalocyanine complexes from which they were derived. The derived phthalocyanine complexes were conjugated to the surface of an azide functionalized silica nanoparticles via copper (1) catalyzed cyclo-addition reaction. All the conjugates showed lower triplet quantum yields ranging from 0.37 to 0.44 compared to the free phthalocyanine complexes. The triplet lifetimes ranged from 352 to 484 μs for the conjugates and from 341 to 366 μs for the free phthalocyanine complexes.

  19. Environment-Responsive Multifunctional Liposomes

    PubMed Central

    Kale, Amit A.; Torchilin, Vladimir P.

    2012-01-01

    Liposomal nanocarriers modified with cell-penetrating peptide and a pH-sensitive PEG shield demonstrate simultaneously a better systemic circulation and site-specific exposure of the cell-penetrating peptide. PEG chains were incorporated into the liposome membrane via the PEG-attached phosphatidylethanolamine (PE) residue with PEG and PE being conjugated with the lowered pH-degradable hydrazone bond (PEG-HZ-PE), while cell-penetrating peptide (TATp) was added as TATp-PEG-PE conjugate. Under normal conditions, liposome-grafted PEG “shielded” liposome-attached TATp moieties, since the PEG spacer for TATp attachment (PEG(1000)) was shorter than protective PEG(2000). PEGylated liposomes accumulate in targets via the EPR effect, but inside the “acidified” tumor or ischemic tissues lose their PEG coating because of the lowered pH-induced hydrolysis of HZ and penetrate inside cells via the now-exposed TATp moieties. pH-responsive behavior of these constructs is successfully tested in cell cultures in vitro as well as in tumors in experimental mice in vivo. These nanocarriers also showed enhanced pGFP transfection efficiency upon intratumoral administration in mice, compared to control pH nonsensitive counterpart. These results can be considered as an important step in the development of tumor-specific stimuli-sensitive drug and gene delivery systems. PMID:20072884

  20. Environment-responsive multifunctional liposomes.

    PubMed

    Kale, Amit A; Torchilin, Vladimir P

    2010-01-01

    Liposomal nanocarriers anchored with a cell-penetrating peptide and a pH-sensitive PEG-shield where later has ability to provide simultaneously better systemic circulation and site-specific exposure of cell penetrating peptide. PEG chains were incorporated into the liposome membrane via the PEG-attached phosphatidylethanolamine (PE) residue with PEG and PE being conjugated with the lowered pH-degradable hydrazone bond (PEG-HZ-PE), while cell-penetrating peptide (TATp) was added as TATp-PEG-PE conjugate. Under normal conditions, liposome-grafted PEG "shielded" liposome-attached TATp moieties, since the PEG spacer for TATp attachment (PEG(1000)) was shorter than protective PEG(2000). PEGylated liposomes accumulate in targets via the EPR effect, but inside the "acidified" tumor or ischemic tissues lose their PEG coating because of the lowered pH-induced hydrolysis of HZ and penetrate inside cells via the now-exposed TATp moieties. pH-responsive behavior of these constructs is successfully tested in cell cultures in vitro as well as in tumors in experimental mice in vivo. These nanocarriers also showed enhanced pGFP transfection efficiency upon intratumoral administration in mice, compared to control pH nonsensitive counterpart. These results can be considered as an important step in the development of tumor-specific stimuli-sensitive drug and gene delivery systems. PMID:20072884

  1. Electronic transport properties of (fluorinated) metal phthalocyanine

    NASA Astrophysics Data System (ADS)

    Fadlallah, M. M.; Eckern, U.; Romero, A. H.; Schwingenschlögl, U.

    2016-01-01

    The magnetic and transport properties of the metal phthalocyanine (MPc) and F16MPc (M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn and Ag) families of molecules in contact with S-Au wires are investigated by density functional theory within the local density approximation, including local electronic correlations on the central metal atom. The magnetic moments are found to be considerably modified under fluorination. In addition, they do not depend exclusively on the configuration of the outer electronic shell of the central metal atom (as in isolated MPc and F16MPc) but also on the interaction with the leads. Good agreement between the calculated conductance and experimental results is obtained. For M = Ag, a high spin filter efficiency and conductance is observed, giving rise to a potentially high sensitivity for chemical sensor applications.

  2. Nonequilibrium spin crossover in copper phthalocyanine

    NASA Astrophysics Data System (ADS)

    Siegert, Benjamin; Donarini, Andrea; Grifoni, Milena

    2016-03-01

    We demonstrate the nonequilibrium tip induced control of the spin state of copper phthalocyanine on an insulator coated substrate. We find that, under the condition of energetic proximity of many-body neutral excited states to the anionic ground state, the system can undergo a population inversion towards these excited states. The resulting state of the system is accompanied by a change in the total spin quantum number. Experimental signatures of the crossover are the appearance of additional nodal planes in the topographical scanning tunneling microscopy images as well as a strong suppression of the current near the center of the molecule. The robustness of the effect against moderate charge conserving relaxation processes has also been tested.

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

    NASA Astrophysics Data System (ADS)

    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

    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.

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

    PubMed

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

    2013-09-01

    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.

  5. Continuous wasteless ecologically safe technology of propylenecarbonate production in presence of phthalocyanine catalysts

    DOEpatents

    Afanasiev, Vladimir Vasilievich; Zefirov, Nikolai Serafimovich; Zalepugin, Dmitry Yurievich; Polyakov, Victor Stanislavovich; Tilkunova,Nataliya Alexandrovna; Tomilova, Larisa Godvigovna

    2009-09-08

    A continuous method of producing propylenecarbonate includes carboxylation of propylene oxide with carbon dioxide in presence of phthalocyanine catalyst on an inert carrier, using as the phthalocyanine catalyst at least one catalyst selected from the group consisting of not-substituted, methyl, ethyl, butyl, and tret butyl-substituted phthalocyanines of metals, including those containing counterions, and using as the carrier a hydrophobic carrier.

  6. 40 CFR 721.9674 - Sulfonated-copper phthalocyanine salt of a triarylmethane dye (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Sulfonated-copper phthalocyanine salt... Significant New Uses for Specific Chemical Substances § 721.9674 Sulfonated-copper phthalocyanine salt of a... chemical substance identified generically as sulfonated-copper phthalocyanine salt of a triarylmethane...

  7. 40 CFR 721.9674 - Sulfonated-copper phthalocyanine salt of a triarylmethane dye (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Sulfonated-copper phthalocyanine salt... Significant New Uses for Specific Chemical Substances § 721.9674 Sulfonated-copper phthalocyanine salt of a... chemical substance identified generically as sulfonated-copper phthalocyanine salt of a triarylmethane...

  8. 40 CFR 721.9674 - Sulfonated-copper phthalocyanine salt of a triarylmethane dye (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Sulfonated-copper phthalocyanine salt... Significant New Uses for Specific Chemical Substances § 721.9674 Sulfonated-copper phthalocyanine salt of a... chemical substance identified generically as sulfonated-copper phthalocyanine salt of a triarylmethane...

  9. 40 CFR 721.9674 - Sulfonated-copper phthalocyanine salt of a triarylmethane dye (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Sulfonated-copper phthalocyanine salt... Significant New Uses for Specific Chemical Substances § 721.9674 Sulfonated-copper phthalocyanine salt of a... chemical substance identified generically as sulfonated-copper phthalocyanine salt of a triarylmethane...

  10. 40 CFR 721.9674 - Sulfonated-copper phthalocyanine salt of a triarylmethane dye (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Sulfonated-copper phthalocyanine salt... Significant New Uses for Specific Chemical Substances § 721.9674 Sulfonated-copper phthalocyanine salt of a... chemical substance identified generically as sulfonated-copper phthalocyanine salt of a triarylmethane...

  11. Capabilities of liposomes for topological transformation.

    PubMed

    Nomura, F; Nagata, M; Inaba, T; Hiramatsu, H; Hotani, H; Takiguchi, K

    2001-02-27

    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. PMID:11226241

  12. Liposome-like Nanostructures for Drug Delivery

    PubMed Central

    Gao, Weiwei; Hu, Che-Ming J.; Fang, Ronnie H.; Zhang, Liangfang

    2013-01-01

    Liposomes are a class of well-established drug carriers that have found numerous therapeutic applications. The success of liposomes, together with recent advancements in nanotechnology, has motivated the development of various novel liposome-like nanostructures with improved drug delivery performance. These nanostructures can be categorized into five major varieties, namely: (1) polymer-stabilized liposomes, (2) nanoparticle-stabilized liposomes, (3) core-shell lipid-polymer hybrid nanoparticles, (4) natural membrane-derived vesicles, and (5) natural membrane coated nanoparticles. They have received significant attention and have become popular drug delivery platforms. Herein, we discuss the unique strengths of these liposome-like platforms in drug delivery, with a particular emphasis on how liposome-inspired novel designs have led to improved therapeutic efficacy, and review recent progress made by each platform in advancing healthcare. PMID:24392221

  13. Design of liposomal formulations for cell targeting.

    PubMed

    Nogueira, Eugénia; Gomes, Andreia C; Preto, Ana; Cavaco-Paulo, Artur

    2015-12-01

    Liposomes have gained extensive attention as carriers for a wide range of drugs due to being both nontoxic and biodegradable as they are composed of substances naturally occurring in biological membranes. Active targeting for cells has explored specific modification of the liposome surface by functionalizing it with specific targeting ligands in order to increase accumulation and intracellular uptake into target cells. None of the Food and Drug Administration-licensed liposomes or lipid nanoparticles are coated with ligands or target moieties to delivery for homing drugs to target tissues, cells or subcellular organelles. Targeted therapies (with or without controlled drug release) are an emerging and relevant research area. Despite of the numerous liposomes reviews published in the last decades, this area is in constant development. Updates urgently needed to integrate new advances in targeted liposomes research. This review highlights the evolution of liposomes from passive to active targeting and challenges in the development of targeted liposomes for specific therapies. PMID:26454541

  14. A comparative photophysicochemical study of phthalocyanines encapsulated in core-shell silica nanoparticles.

    PubMed

    Fashina, Adedayo; Amuhaya, Edith; Nyokong, Tebello

    2015-02-25

    This work presents the synthesis and characterization of a new zinc phthalocyanine complex tetrasubstituted with 3-carboxyphenoxy in the peripheral position. The photophysical properties of the new complex are compared with those of phthalocyanines tetra substituted with 3-carboxyphenoxy or 4-carboxyphenoxy at non-peripheral positions. Three phthalocyanine complexes were encapsulated within silica matrix to form a core shell and the hybrid nanoparticles particles obtained were spherical and mono dispersed. When encapsulated within the silica shell nanoparticles, phthalocyanines showed improved triplet quantum yields and singlet oxygen quantum yields than surface grafted derivatives. The improvements observed could be attributed to the protection provided for the phthalocyanine complexes by the silica matrix.

  15. Pulmonary uptake of liposomal phosphatidylcholine.

    PubMed

    Zachman, R D; Tsao, F H

    1980-01-01

    Liposomes prepared with phosphatidylcholine (PC) labeled with [1-14C]-dipalmitoyl-PC, dicetylphosphate, cholesterol (molar ratio 7:2:1) were injected into the right ear vein of 2-month-old male rabbits. At 5, 60, and 120 min after injection, organs were removed and analyzed for [14C]-PC. Lung, liver, and spleen took up the [14C]-PC by 5 min. Spleen accumulation of [14C]-PC increased steadily, liver plateaued from 1--2 hr, and lung fell rapidly. The uptake of liposomal [14C]-PC by lung and liver was dependent on the concentration of iv injected liposomal [14C]-PC. All lung subcellular fractions (lamellar bodies, mitochondria, and microsomes) took up [14C]-PC. Lamellar body [14C]-PC was highest at 5 min, and then decreased. Still, on a nmole/mg protein basis, uptake of [14C]-PC by lamellar bodies was higher than other organelle fractions. Of the radioactivity in lung, 95% was [14C]-PC even after 2 hr, whereas by 1 hr, 28% of liposomal PC absorbed by liver had been degraded. PMID:7360518

  16. Liposomal bupivacaine and clinical outcomes.

    PubMed

    Tong, Yi Cai Isaac; Kaye, Alan David; Urman, Richard D

    2014-03-01

    In the multimodal approach to the management of postoperative pain, local infiltration and regional blocks have been increasingly utilized for pain control. One of the limitations of local anesthetics in the postoperative setting is its relatively short duration of action. Multivesicular liposomes containing bupivacaine have been increasingly utilized for their increased duration of action. Compared with bupivacaine HCl, local infiltration of liposomal bupivacaine has shown to have an increase in duration of action and causes delay in peak plasma concentration. In this article, we attempt to review the clinical literature surrounding liposomal bupivacaine and its evolving role in perioperative analgesia. This new bupivacaine formation may have promising implications in postoperative pain control, resulting in increased patient satisfaction and a decrease in both hospital stay and opioid-induced adverse events (AEs). Although more studies are needed, the preliminary clinical trials suggest that liposomal bupivacaine has predictable pharmacokinetics, a similar side effect profile compared with bupivacaine HCl, and is effective in providing increased postoperative pain control.

  17. Capacious and programmable multi-liposomal carriers

    NASA Astrophysics Data System (ADS)

    Yaroslavov, Alexander A.; Sybachin, Andrey V.; Zaborova, Olga V.; Migulin, Vasiliy A.; Samoshin, Vyacheslav V.; Ballauff, Matthias; Kesselman, Ellina; Schmidt, Judith; Talmon, Yeshayahu; Menger, Fredric M.

    2015-01-01

    Spherical polycationic brushes (SPBs) were synthesized by grafting polycationic chains onto 100 nm polystyrene particles. These particles were exposed to unilamellar egg-lecithin (EL) liposomes with a mean diameter of 40 nm that had been rendered anionic via the presence of 10 molar% of phosphatidylserine (PS1-). The liposomes also contained 30 mole% of a morpholinocyclohexanol-based lipid (MOCH) that undergoes a conformational flip when the pH is decreased from 7.0 to 5.0. Mixtures of SPBs and liposomes at pH 7 gave an electrostatically-driven complex possessing, on average, about 40 liposomes for each SPB particle. It was found that the bound liposomes rapidly release much of their contents when the pH is reduced from 7.0 to 5.0 owing mostly to a MOCH conformational change that creates defects in the bilayer membrane. The drop in pH does not, however, induce a separation of the liposomes from the SPBs. Around 50-60% of the liposome contents escape before, it is reasoned, lateral and transmembrane motion of the membrane components heals the defects and prevents further release. Remarkably, the liposomes complexed with SPB release their cargo much faster than the identical but non-complexed liposomes.Spherical polycationic brushes (SPBs) were synthesized by grafting polycationic chains onto 100 nm polystyrene particles. These particles were exposed to unilamellar egg-lecithin (EL) liposomes with a mean diameter of 40 nm that had been rendered anionic via the presence of 10 molar% of phosphatidylserine (PS1-). The liposomes also contained 30 mole% of a morpholinocyclohexanol-based lipid (MOCH) that undergoes a conformational flip when the pH is decreased from 7.0 to 5.0. Mixtures of SPBs and liposomes at pH 7 gave an electrostatically-driven complex possessing, on average, about 40 liposomes for each SPB particle. It was found that the bound liposomes rapidly release much of their contents when the pH is reduced from 7.0 to 5.0 owing mostly to a MOCH conformational

  18. Essential oils encapsulated in liposomes: a review.

    PubMed

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

    2013-12-01

    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.

  19. Tunable charge transfer properties in metal-phthalocyanine heterojunctions

    NASA Astrophysics Data System (ADS)

    Siles, P. F.; Hahn, T.; Salvan, G.; Knupfer, M.; Zhu, F.; Zahn, D. R. T.; Schmidt, O. G.

    2016-04-01

    Organic materials such as phthalocyanine-based systems present a great potential for organic device applications due to the possibility of integrating films of different organic materials to create organic heterostructures which combine the electrical capabilities of each material. This opens the possibility to precisely engineer and tune new electrical properties. In particular, similar transition metal phthalocyanines demonstrate hybridization and charge transfer properties which could lead to interesting physical phenomena. Although, when considering device dimensions, a better understanding and control of the tuning of the transport properties still remain in the focus of research. Here, by employing conductive atomic force microscopy techniques, we provide an insight about the nanoscale electrical properties and transport mechanisms of MnPc and fluorinated phthalocyanines such as F16CuPc and F16CoPc. We report a transition from typical diode-like transport mechanisms for pure MnPc thin films to space-charge-limited current transport regime (SCLC) for Pc-based heterostructures. The controlled addition of fluorinated phthalocyanine also provides highly uniform and symmetric-polarized transport characteristics with conductance enhancements up to two orders of magnitude depending on the polarization. We present a method to spatially map the mobility of the MnPc/F16CuPc structures with a nanoscale resolution and provide theoretical calculations to support our experimental findings. This well-controlled nanoscale tuning of the electrical properties for metal transition phthalocyanine junctions stands as key step for future phthalocyanine-based electronic devices, where the low dimension charge transfer, mediated by transition metal atoms could be intrinsically linked to a transfer of magnetic moment or spin.Organic materials such as phthalocyanine-based systems present a great potential for organic device applications due to the possibility of integrating films of

  20. Electrocatalytic activity of phthalocyanines in secondary lithium cells

    SciTech Connect

    Wohrle, D.; Kirchenmann, M.

    1985-05-01

    The feasibility of cathodes containing low molecular unsubstituted phthalocyanines in secondary lithium cells was studied by Yamaki and Yamaji. They reported values of discharge capacities of more than 17 electrons per molecule of phthalocyanine requiring the intercalation of the equivalent number of charge compensating lithium cations. The extensive literature concerning the properties of phthalocyanines, namely, electrochemical and chemical redox equilibria, suggests a reversible reduction of up to four electrons per molecule. The apparent discrepancies gave rise to a more detailed investigation of the electrochemistry of the cell. At the same time, the properties of low molecular copper octacyanophthalocyanine 2 and copperpolyphthalocyanine 3 were tested in the same cell reaction. The structures of the compounds are given.

  1. Magnetic anisotropy of metal functionalized phthalocyanine 2D networks

    NASA Astrophysics Data System (ADS)

    Zhu, Guojun; Zhang, Yun; Xiao, Huaping; Cao, Juexian

    2016-06-01

    The magnetic anisotropy of metal including Cr, Mn, Fe, Co, Mo, Tc, Ru, Rh, W, Re, Os, Ir atoms functionalized phthalocyanine networks have been investigated with first-principles calculations. The magnetic moments can be expressed as 8-n μB with n the electronic number of outmost d shell in the transition metals. The huge magnetocrystalline anisotropy energy (MAE) is obtained by torque method. Especially, the MAE of Re functionalized phthalocyanine network is about 20 meV with an easy axis perpendicular to the plane of phthalocyanine network. The MAE is further manipulated by applying the external biaxial strain. It is found that the MAE is linear increasing with the external strain in the range of -2% to 2%. Our results indicate an effective approach to modulate the MAE for practical application.

  2. Thin films of tetrafluorosubstituted cobalt phthalocyanine: Structure and sensor properties

    NASA Astrophysics Data System (ADS)

    Klyamer, Darya D.; Sukhikh, Aleksandr S.; Krasnov, Pavel O.; Gromilov, Sergey A.; Morozova, Natalya B.; Basova, Tamara V.

    2016-05-01

    In this work, thin films of tetrafluorosubstituted cobalt phthalocyanine (CoPcF4) were prepared by organic molecular beam deposition and their structure was studied using UV-vis, polarization dependent Raman spectroscopy, XRD and atomic force microscopy. Quantum chemical calculations (DFT) have been employed in order to determine the detailed assignment of the bands in the CoPcF4 IR and Raman spectra. The electrical sensor response of CoPcF4 films to ammonia vapours was investigated and compared with that of unsubstituted cobalt phthalocyanine films. In order to explain the difference in sensitivity of the unsubstituted and fluorinated phthalocyanines to ammonia, the nature and properties of chemical binding between CoPc derivatives and NH3 were described by quantum-chemical calculations utilizing DFT method. The effect of post-deposition annealing on surface morphology and gas sensing properties of CoPcF4 films was also studied.

  3. Phthalocyanine-assisted photodynamic inactivation of pathogenic microorganisms

    NASA Astrophysics Data System (ADS)

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

    2007-03-01

    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 as follows: 1. for the aqua supernatants obtained after 10 min cell incubation with the respected phthalocyanines (1.6 μmol.l -1), 2. for the washed from the unbound dye cells, and 3. for the organic extracts from the three times washed cells. Fluorescent intensities at the emission maximum (~690 nm) were compared to the spectra of the phthalocyanines in organic solutions. The phthalocyanines uptake data for bacteria and fungi were determined at different cell densities. Nevertheless the better fluorescence properties of AlPc (fluorescent quantum yield of 0.4 towards 0.3 for ZnPcs) the lower drug accumulation in microorganisms was obtained. PDI results indicated an intensive lowering of the bacterial survival of both strains of S. aureus treated with cationic ZnPcMe followed by the anionic ZnPcS, at irradiance of 100 mW cm -2 and fluence rate of 60 J cm -2. More resistant to phototreatment P. aeruginosa and morphologically complicated yeast C. albicans were successfully inactivated only with cationic ZnPcMe. These data indicate the promising future application of cationic phthalocyanine in photodynamic inactivation of pathogenic microorganisms.

  4. Tunable charge transfer properties in metal-phthalocyanine heterojunctions.

    PubMed

    Siles, P F; Hahn, T; Salvan, G; Knupfer, M; Zhu, F; Zahn, D R T; Schmidt, O G

    2016-04-28

    Organic materials such as phthalocyanine-based systems present a great potential for organic device applications due to the possibility of integrating films of different organic materials to create organic heterostructures which combine the electrical capabilities of each material. This opens the possibility to precisely engineer and tune new electrical properties. In particular, similar transition metal phthalocyanines demonstrate hybridization and charge transfer properties which could lead to interesting physical phenomena. Although, when considering device dimensions, a better understanding and control of the tuning of the transport properties still remain in the focus of research. Here, by employing conductive atomic force microscopy techniques, we provide an insight about the nanoscale electrical properties and transport mechanisms of MnPc and fluorinated phthalocyanines such as F16CuPc and F16CoPc. We report a transition from typical diode-like transport mechanisms for pure MnPc thin films to space-charge-limited current transport regime (SCLC) for Pc-based heterostructures. The controlled addition of fluorinated phthalocyanine also provides highly uniform and symmetric-polarized transport characteristics with conductance enhancements up to two orders of magnitude depending on the polarization. We present a method to spatially map the mobility of the MnPc/F16CuPc structures with a nanoscale resolution and provide theoretical calculations to support our experimental findings. This well-controlled nanoscale tuning of the electrical properties for metal transition phthalocyanine junctions stands as key step for future phthalocyanine-based electronic devices, where the low dimension charge transfer, mediated by transition metal atoms could be intrinsically linked to a transfer of magnetic moment or spin.

  5. Tunable charge transfer properties in metal-phthalocyanine heterojunctions.

    PubMed

    Siles, P F; Hahn, T; Salvan, G; Knupfer, M; Zhu, F; Zahn, D R T; Schmidt, O G

    2016-04-28

    Organic materials such as phthalocyanine-based systems present a great potential for organic device applications due to the possibility of integrating films of different organic materials to create organic heterostructures which combine the electrical capabilities of each material. This opens the possibility to precisely engineer and tune new electrical properties. In particular, similar transition metal phthalocyanines demonstrate hybridization and charge transfer properties which could lead to interesting physical phenomena. Although, when considering device dimensions, a better understanding and control of the tuning of the transport properties still remain in the focus of research. Here, by employing conductive atomic force microscopy techniques, we provide an insight about the nanoscale electrical properties and transport mechanisms of MnPc and fluorinated phthalocyanines such as F16CuPc and F16CoPc. We report a transition from typical diode-like transport mechanisms for pure MnPc thin films to space-charge-limited current transport regime (SCLC) for Pc-based heterostructures. The controlled addition of fluorinated phthalocyanine also provides highly uniform and symmetric-polarized transport characteristics with conductance enhancements up to two orders of magnitude depending on the polarization. We present a method to spatially map the mobility of the MnPc/F16CuPc structures with a nanoscale resolution and provide theoretical calculations to support our experimental findings. This well-controlled nanoscale tuning of the electrical properties for metal transition phthalocyanine junctions stands as key step for future phthalocyanine-based electronic devices, where the low dimension charge transfer, mediated by transition metal atoms could be intrinsically linked to a transfer of magnetic moment or spin. PMID:27049842

  6. Controllable fabrication of copper phthalocyanine nanostructure crystals.

    PubMed

    Liu, Fangmei; Sun, Jia; Xiao, Si; Huang, Wenglong; Tao, Shaohua; Zhang, Yi; Gao, Yongli; Yang, Junliang

    2015-06-01

    Copper phthalocyanine (CuPc) nanostructure crystals, including nanoflower, nanoribbon, and nanowire, were controllably fabricated by temperature gradient physical vapor deposition (TG-PVD) through controlling the growth parameters. In a controllable growth system with carrier gas N2, nanoflower, nanoribbon, and nanowire crystals were formed in a high-temperature zone, medium-temperature zone, and low-temperature zone, respectively. They were proved to be β-phase, coexist of α-phase and β-phase, and α-phase respectively based on x-ray diffraction results. Furthermore, ultralong CuPc nanowires up to several millimeters could be fabricated by TG-PVD without carrier gas, and they were well-aligned to form large-area CuPc nanowire crystal arrays by the Langmuir-Blodgett method. The nanostructure crystals showed unusual optical absorption spectra from the ultraviolet-visible to near-infrared range, which was explained by the diffraction and scattering caused by the wavelength-sized nanostructures. These CuPc nanostructure crystals show potential applications in organic electronic and optoelectronic devices.

  7. Functionalization of nanocrystalline diamond films with phthalocyanines

    NASA Astrophysics Data System (ADS)

    Petkov, Christo; Reintanz, Philipp M.; Kulisch, Wilhelm; Degenhardt, Anna Katharina; Weidner, Tobias; Baio, Joe E.; Merz, Rolf; Kopnarski, Michael; Siemeling, Ulrich; Reithmaier, Johann Peter; Popov, Cyril

    2016-08-01

    Phthalocyanine (Pc) derivatives containing different central metal atoms (Mn, Cu, Ti) and different peripheral chains were synthesized and comprehensively characterized. Their interaction with nanocrystalline diamond (NCD) films, as-grown by hot-filament chemical vapor deposition or after their modification with oxygen plasma to exchange the hydrogen termination with oxygen-containing groups, was studied by X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The elemental composition as determined by XPS showed that the Pc were grafted on both as-grown and O-terminated NCD. Mn, Cu and Ti were detected together with N stemming from the Pc ring and S in case of the Ti-Pc from the peripheral ligands. The results for the elemental surface composition and the detailed study of the N 1s, S 2p and O 1s core spectra revealed that Ti-Pc grafted better on as-grown NCD but Cu-Pc and Mn-Pc on O-terminated films. Samples of Mn-Pc on as-grown and O-terminated NCD were further investigated by NEXAFS spectroscopy. The results showed ordering of the grafted molecules, laying flat on the H-terminated NCD surface while only the macrocycles were oriented parallel to the O-terminated surface with the peripheral chains perpendicular to it.

  8. Controllable fabrication of copper phthalocyanine nanostructure crystals.

    PubMed

    Liu, Fangmei; Sun, Jia; Xiao, Si; Huang, Wenglong; Tao, Shaohua; Zhang, Yi; Gao, Yongli; Yang, Junliang

    2015-06-01

    Copper phthalocyanine (CuPc) nanostructure crystals, including nanoflower, nanoribbon, and nanowire, were controllably fabricated by temperature gradient physical vapor deposition (TG-PVD) through controlling the growth parameters. In a controllable growth system with carrier gas N2, nanoflower, nanoribbon, and nanowire crystals were formed in a high-temperature zone, medium-temperature zone, and low-temperature zone, respectively. They were proved to be β-phase, coexist of α-phase and β-phase, and α-phase respectively based on x-ray diffraction results. Furthermore, ultralong CuPc nanowires up to several millimeters could be fabricated by TG-PVD without carrier gas, and they were well-aligned to form large-area CuPc nanowire crystal arrays by the Langmuir-Blodgett method. The nanostructure crystals showed unusual optical absorption spectra from the ultraviolet-visible to near-infrared range, which was explained by the diffraction and scattering caused by the wavelength-sized nanostructures. These CuPc nanostructure crystals show potential applications in organic electronic and optoelectronic devices. PMID:25961155

  9. Controllable fabrication of copper phthalocyanine nanostructure crystals

    NASA Astrophysics Data System (ADS)

    Liu, Fangmei; Sun, Jia; Xiao, Si; Huang, Wenglong; Tao, Shaohua; Zhang, Yi; Gao, Yongli; Yang, Junliang

    2015-06-01

    Copper phthalocyanine (CuPc) nanostructure crystals, including nanoflower, nanoribbon, and nanowire, were controllably fabricated by temperature gradient physical vapor deposition (TG-PVD) through controlling the growth parameters. In a controllable growth system with carrier gas N2, nanoflower, nanoribbon, and nanowire crystals were formed in a high-temperature zone, medium-temperature zone, and low-temperature zone, respectively. They were proved to be β-phase, coexist of α-phase and β-phase, and α-phase respectively based on x-ray diffraction results. Furthermore, ultralong CuPc nanowires up to several millimeters could be fabricated by TG-PVD without carrier gas, and they were well-aligned to form large-area CuPc nanowire crystal arrays by the Langmuir-Blodgett method. The nanostructure crystals showed unusual optical absorption spectra from the ultraviolet-visible to near-infrared range, which was explained by the diffraction and scattering caused by the wavelength-sized nanostructures. These CuPc nanostructure crystals show potential applications in organic electronic and optoelectronic devices.

  10. Effect of pyridine on infrared absorption spectra of copper phthalocyanine.

    PubMed

    Singh, Sukhwinder; Tripathi, S K; Saini, G S S

    2008-02-01

    Infrared absorption spectra of copper phthalocyanine in KBr pellet and pyridine solution in 400-1625 and 2900-3200 cm(-1)regions are reported. In the IR spectra of solid sample, presence of weak bands, which are forbidden according to the selection rules of D4h point group, is explained on the basis of distortion in the copper phthalocyanine molecule caused by the crystal packing effects. Observation of a new band at 1511 cm(-1) and change in intensity of some other bands in pyridine are interpreted on the basis of coordination of the solvent molecule with the central copper ion.

  11. New biotinylated phthalocyanines for the photodynamic therapy of cancer

    NASA Astrophysics Data System (ADS)

    Hirth, Andreas; Bartik, Bernd; Bogdahn-Rai, Tatjana; Woehrle, Dieter; Kaul, Sepp

    1997-12-01

    Suitable substituted phthalocyanines are promising and widely investigated photosensitizers (PS) for the photodynamic therapy of cancer (PDT). However, selective accumulation of the PSs in tumor tissues, avoiding contamination of healthy tissues, is still an unsolved central problem. We present first results on the synthesis of new biotinylated phthalocyanines as potentially selective photosensitizers when applied in a polyphasic tumor targeting (tumor cell plus first step: biotinylated/monoclonal antibody, second step: streptavidin, and third step: biotinylated PS). The binding and the photodynamic activity of biotinylated PS in this three step model is shown in tumor cell lines.

  12. Bupivacaine liposomal versus bupivacaine: comparative review.

    PubMed

    Noviasky, John; Pierce, Deirdre P; Whalen, Karen; Guharoy, Roy; Hildreth, Kenneth

    2014-06-01

    Bupivacaine liposomal injection was recently approved by the US Food and Drug Administration (FDA) as a local anesthetic for use in management of postsurgical pain in adults. When compared to placebo, bupivacaine liposomal decreases postoperative pain and opioid use. This review examines the efficacy of bupivacaine liposomal when compared to conventional bupivacaine ± epinephrine using published and unpublished data provided to the FDA by the manufacturer. PMID:24958971

  13. [CT kinetics of intratumor liposome deposits].

    PubMed

    Wowra, B; Mentrup, E; Zeller, W J; Stricker, H; Sturm, V

    1988-04-01

    CT follow-up studies of liposome-entrapped metrizamide after intraneoplastic injection into neurogenic s.c. rat tumors were performed. By closely resembling clinical examination conditions, the experimental design has proven suitable in determining the in vivo kinetics of these interstitial liposome deposits. When compared to free metrizamide which may be considered an analogue of water-soluble chemotherapeutics, the encapsulation of metrizamide in liposomes resulted in a retarded decline of the contrast enhancement. Diffusion of liposomes could not be detected and the X-ray attenuation values measured within the liposome deposits continuously decreased with time for both types of liposomes. In the case of multilamellar vesicles, this significantly corresponded to a zero order kinetics with a mean halflife of 300 h. An initial increment in the X-ray attenuation of the liposome deposits might be due to the interstitial absorption of the water component of the liposome-dispersion. Because of the pronounced retardation effect of multilamellar liposomes resulting in a 140-fold prolongation of the interstitial retention time of metrizamide and due to their release kinetics these vesicles may be an appropriate carrier system for a local interstitial chemotherapy modality. Small unilamellar vesicles having an interstitial half-life of 14 h may be used as a faster component of a composed therapy system.

  14. Capacious and programmable multi-liposomal carriers.

    PubMed

    Yaroslavov, Alexander A; Sybachin, Andrey V; Zaborova, Olga V; Migulin, Vasiliy A; Samoshin, Vyacheslav V; Ballauff, Matthias; Kesselman, Ellina; Schmidt, Judith; Talmon, Yeshayahu; Menger, Fredric M

    2015-02-01

    Spherical polycationic brushes (SPBs) were synthesized by grafting polycationic chains onto 100 nm polystyrene particles. These particles were exposed to unilamellar egg-lecithin (EL) liposomes with a mean diameter of 40 nm that had been rendered anionic via the presence of 10 molar% of phosphatidylserine (PS(1-)). The liposomes also contained 30 mole% of a morpholinocyclohexanol-based lipid (MOCH) that undergoes a conformational flip when the pH is decreased from 7.0 to 5.0. Mixtures of SPBs and liposomes at pH 7 gave an electrostatically-driven complex possessing, on average, about 40 liposomes for each SPB particle. It was found that the bound liposomes rapidly release much of their contents when the pH is reduced from 7.0 to 5.0 owing mostly to a MOCH conformational change that creates defects in the bilayer membrane. The drop in pH does not, however, induce a separation of the liposomes from the SPBs. Around 50-60% of the liposome contents escape before, it is reasoned, lateral and transmembrane motion of the membrane components heals the defects and prevents further release. Remarkably, the liposomes complexed with SPB release their cargo much faster than the identical but non-complexed liposomes. PMID:25554444

  15. Interaction of rotavirus particles with liposomes.

    PubMed

    Nandi, P; Charpilienne, A; Cohen, J

    1992-06-01

    We have studied the interactions of purified viral particles with liposomes as a model to understand the mechanism of entry of rotavirus into the cell. Liposomes, made from pure as well as mixed lipids, that contained encapsulated self-quenching concentrations of the fluorophore carboxyfluorescein (CF) were used. Rotavirus-liposome interactions were studied from the fluorescence dequenching of CF resulting from its release to the bulk solution. Purified infectious double-shelled virus particles induced a concentration- and temperature-dependent release of CF. The rate and extent of CF release was maximum between pH 7.3 and 7.6. The removal of outer structural proteins VP4 and VP7 from virus, which results in the formation of single-shelled particles, prevented virus interaction with liposomes. Rotavirus particles with uncleaved VP4 did not interact with liposomes, but treatment in situ of these particles with trypsin restored the interaction with the liposomes and resulted in CF dequenching. Our data support the view that rotavirus enters the cell through direct penetration of the plasma membrane. In contrast, adenovirus, the only other nonenveloped virus studied by this method, shows the optimum rate of marker release from liposomes at around pH 6 (R. Blumenthal, P. S. Seth, M. C. Willingham, and I. Pastan, Biochemistry 25:2231-2237, 1986). The interaction between rotavirus and liposomes is sensitive to specific divalent metal ions, unlike the adenovirus-liposome interaction, which is independent of them. PMID:1316453

  16. Excited-State Deactivation of Branched Phthalocyanine Compounds.

    PubMed

    Zhu, Huaning; Li, Yang; Chen, Jun; Zhou, Meng; Niu, Yingli; Zhang, Xinxing; Guo, Qianjin; Wang, Shuangqing; Yang, Guoqiang; Xia, Andong

    2015-12-21

    The excited-state relaxation dynamics and chromophore interactions in two phthalocyanine compounds (bis- and trisphthalocyanines) are studied by using steady-state and femtosecond transient absorption spectral measurements, where the excited-state energy-transfer mechanism is explored. By exciting phthalocyanine compounds to their second electronically excited states and probing the subsequent relaxation dynamics, a multitude of deactivation pathways are identified. The transient absorption spectra show the relaxation pathway from the exciton state to excimer state and then back to the ground state in bisphthalocyanine (bis-Pc). In trisphthalocyanine (tris-Pc), the monomeric and dimeric subunits are excited and the excitation energy transfers from the monomeric vibrationally hot S1 state to the exciton state of a pre-associated dimer, with subsequent relaxation to the ground state through the excimer state. The theoretical calculations and steady-state spectra also show a face-to-face conformation in bis-Pc, whereas in tris-Pc, two of the three phthalocyanine branches form a pre-associated face-to-face dimeric conformation with the third one acting as a monomeric unit; this is consistent with the results of the transient absorption experiments from the perspective of molecular structure. The detailed structure-property relationships in phthalocyanine compounds is useful for exploring the function of molecular aggregates in energy migration of natural photosynthesis systems.

  17. Amphiphilic phthalocyanine-cyclodextrin conjugates for cancer photodynamic therapy.

    PubMed

    Lourenço, Leandro M O; Pereira, Patrícia M R; Maciel, Elisabete; Válega, Mónica; Domingues, Fernando M J; Domingues, Maria R M; Neves, Maria G P M S; Cavaleiro, José A S; Fernandes, Rosa; Tomé, João P C

    2014-08-01

    Three phthalocyanines (Pcs) conjugated with α-, β- and γ-cyclodextrins (CDs) were prepared and their application as photosensitizer (PS) agents was assessed by photophysical, photochemical and in vitro photobiological studies. The photoactivity of Pc-α-CD and Pc-γ-CD ensures their potential as PDT drugs against UM-UC-3 human bladder cancer cells. PMID:24943806

  18. LASERS IN MEDICINE: Two-photon excitation of aluminium phthalocyanines

    NASA Astrophysics Data System (ADS)

    Meshalkin, Yu P.; Alfimov, E. E.; Vasil'ev, N. E.; Denisov, A. N.; Makukha, V. K.; Ogirenko, A. P.

    1999-12-01

    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.

  19. Photodynamic evaluation of tetracarboxy-phthalocyanines in model systems.

    PubMed

    Alonso, Lais; Sampaio, Renato N; Souza, Thalita F M; Silva, Rodrigo C; Neto, Newton M Barbosa; Ribeiro, Anderson O; Alonso, Antonio; Gonçalves, Pablo J

    2016-08-01

    The present work reports the synthesis, photophysical and photochemical characterization and photodynamic evaluation of zinc, aluminum and metal free-base tetracarboxy-phthalocyanines (ZnPc, AlPc and FbPc, respectively). To evaluate the possible application of phthalocyanines as a potential photosensitizer the photophysical and photochemical characterization were performed using aqueous (phosphate-buffered solution, PBS) and organic (dimethyl sulfoxide, DMSO) solvents. The relative lipophilicity of the compounds was estimated by the octanol-water partition coefficient and the photodynamic activity evaluated through the photooxidation of a protein and photohemolysis. The photooxidation rate constants (k) were obtained and the hemolytic potential was evaluated by the maximum percentage of hemolysis achieved (Hmax) and the time (t50) to reach 50% of the Hmax. Although these phthalocyanines are all hydrophilic and possess very low affinity for membranes (log PO/W=-2.0), they led to significant photooxidation of bovine serum albumin (BSA) and photohemolysis. Our results show that ZnPc was the most efficient photosensitizer, followed by AlPc and FbPc; this order is the same as the order of the triplet and singlet oxygen quantum yields (ZnPc>AlPc>FbPc). Furthermore, together, the triplet, fluorescence and singlet oxygen quantum yields of zinc tetracarboxy-phthalocyanines suggest their potential for use in theranostic applications, which simultaneously combines photodiagnosis and phototherapy.

  20. Photodynamic evaluation of tetracarboxy-phthalocyanines in model systems.

    PubMed

    Alonso, Lais; Sampaio, Renato N; Souza, Thalita F M; Silva, Rodrigo C; Neto, Newton M Barbosa; Ribeiro, Anderson O; Alonso, Antonio; Gonçalves, Pablo J

    2016-08-01

    The present work reports the synthesis, photophysical and photochemical characterization and photodynamic evaluation of zinc, aluminum and metal free-base tetracarboxy-phthalocyanines (ZnPc, AlPc and FbPc, respectively). To evaluate the possible application of phthalocyanines as a potential photosensitizer the photophysical and photochemical characterization were performed using aqueous (phosphate-buffered solution, PBS) and organic (dimethyl sulfoxide, DMSO) solvents. The relative lipophilicity of the compounds was estimated by the octanol-water partition coefficient and the photodynamic activity evaluated through the photooxidation of a protein and photohemolysis. The photooxidation rate constants (k) were obtained and the hemolytic potential was evaluated by the maximum percentage of hemolysis achieved (Hmax) and the time (t50) to reach 50% of the Hmax. Although these phthalocyanines are all hydrophilic and possess very low affinity for membranes (log PO/W=-2.0), they led to significant photooxidation of bovine serum albumin (BSA) and photohemolysis. Our results show that ZnPc was the most efficient photosensitizer, followed by AlPc and FbPc; this order is the same as the order of the triplet and singlet oxygen quantum yields (ZnPc>AlPc>FbPc). Furthermore, together, the triplet, fluorescence and singlet oxygen quantum yields of zinc tetracarboxy-phthalocyanines suggest their potential for use in theranostic applications, which simultaneously combines photodiagnosis and phototherapy. PMID:27232148

  1. Biophysical studies on chitosan-coated liposomes.

    PubMed

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

    2009-10-01

    Liposomes have been used as delivery vehicles for stabilizing drugs, overcoming barriers to cellular and tissue uptake, and for directing their contents toward specific sites in vivo. Chitosan is a biological macromolecule derived from crustacean shells and has several emerging applications in drug development, obesity control, and tissue engineering. In the present work, the interaction between chitosan and dipalmitoyl phosphatidylcholine (DPPC) liposomes was studied by transmission electron microscopy (TEM), zeta potential, solubilization using the nonionic detergent octylglucoside (OG), as well as Fourier transform infrared (FTIR) spectroscopy and viscosity measurements. The coating of DPPC liposomes by a chitosan layer was confirmed by electron microscope images and the zeta potential of liposomes. Coating of liposome by chitosan resulted in an increase in liposomal size by addition of a layer of 92 +/- 27.1 nm. The liposomal zeta potential became increasingly positive as chitosan concentration increased from 0.1 to 0.3% w/v, then it held at a relatively constant value. The amount of detergent needed to completely solubilize the liposomal membrane was increased after coating of liposomes with chitosan, indicating an increased membrane resistance to the detergent and hence a change in the natural membrane permeation properties. In the analysis of FTIR spectra of DPPC, the symmetric and antisymmetric CH(2) (at 2,800-3,000 cm(-1)) bands and the C=O (at 1,740 cm(-1)) stretching band were investigated in the absence and presence of the chitosan. It was concluded that appropriate combining of the liposomal and chitosan characteristics might be utilized for the improvement of the therapeutic efficacy of liposomes as a drug delivery system.

  2. Nanoparticle Stabilized Liposomes for Acne Therapy

    NASA Astrophysics Data System (ADS)

    Fu, Victoria

    Acne vulgaris is a common skin disease that affects over 40 million people in the United States alone. The main cause of acne vulgaris is Propionibacterium acnes (P. acnes), resides deep in the pores and follicles of the skin in order to feed on oil produced by the sebaceous glands. The liposome is a lipid based nanoparticle with numerous advantages over free drug molecules as an acne treatment alternative. Bare liposomes loaded with lauric acid (LipoLA) were found to show strong antimicrobial activity against P. acnes while generating minimal toxicity. However, the platform is limited by the spontaneous tendency of liposomes to fuse with each other. Attaching nanoparticles to the surface of liposomes can overcome this challenge by providing steric repulsion and reduce surface tension. Thus, carboxyl-functionalized gold nanoparticles (AuC) were attached to the surface of liposomes (AuC-liposomes) loaded with doxycycline, a general tetracycline antibiotic. These particles were found to have a diameter of 120 nm and a zeta potential of 20.0 mV. Both fluorescent and antimicrobial studies demonstrated that based on electrostatic interaction, negatively charged AuC attached to the liposome's positively charged surface and stabilized liposomes in a neutral pH environment (pH = 7.4). Upon entering the skin's acidic environment (pH = 4), AuC detached from the liposome's surface and liposomes could fuse with P. acnes residing in the pores. Furthermore, toxicity studies showed that AuC-liposomes did not induce any significant toxicity, while two of the leading over-the-counter therapies, benzoyl peroxide and salicylic acid, generated substantial skin irritation.

  3. Electronic properties of the interface between hexadecafluoro copper phthalocyanine and unsubstituted copper phthalocyanine films

    SciTech Connect

    Komolov, A. S. Lazneva, E. F.; Pshenichnyuk, S. A.; Gavrikov, A. A.; Chepilko, N. S.; Tomilov, A. A.; Gerasimova, N. B.; Lezov, A. A.; Repin, P. S.

    2013-07-15

    The formation of an interface during the deposition of unsubstituted copper phthalocyanine (CuPc) films on the surface of hexadecafluoro copper phthalocyanine (F{sub 16}-CuPc) films is studied. An incident low-energy electron beam with energies from 0 to 25 eV is used to test the surface under study according to the very-low-energy electron-diffraction technique (VLEED) in the mode of total current spectroscopy. For F{sub 16}-CuPc films, the structure of the maxima in the total current spectra and its main differences from the structure of the maxima for the CuPc film are determined in the energy range from 5 to 15 eV above the Fermi level. The differences in the structure of vacant electron orbitals for CuPc and F{sub 16}-CuPc are also revealed using density functional theory calculations. As a result of an analysis of variations in the intensities of the total current spectra of the CuPc and F{sub 16}-CuPc films, it is assumed that an intermediate layer up to 1 nm thick appears during the formation of an interface between these films, which is characterized by a spread of the features in the total current spectrum. The height, width, and change in the work function are determined for the studied F{sub 16}-CuPc/NuPc interface barrier. A decrease in the level of vacuum by 0.7 eV occurs in the boundary region, which corresponds to electron density transfer from the CuPc film toward the F{sub 16}-CuPc substrate.

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

    PubMed

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

    2012-05-01

    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.

  5. Phthalocyanine photosensitizers as contrast agents for in vivo photoacoustic tumor imaging.

    PubMed

    Attia, Amalina Bte Ebrahim; Balasundaram, Ghayathri; Driessen, Wouter; Ntziachristos, Vasilis; Olivo, Malini

    2015-02-01

    There is a need for contrast agents for non-invasive diagnostic imaging of tumors. Herein, Multispectral Optoacoustic Tomography (MSOT) was employed to evaluate phthalocyanines commonly used in photodynamic therapy as photoacoustic contrast agents. We studied the photoacoustic activity of three water-soluble phthalocyanine photosensitizers: phthalocyanine tetrasulfonic acid (PcS4), Zn(II) phthalocyanine tetrasulfonic acid (ZnPcS4) and Al(III) phthalocyanine chloride tetrasulfonic acid (AlPcS4) in phantom and in tumor-bearing mice to investigate the biodistribution and fate of the phthalocyanines in the biological tissues. PcS4 was observed to grant good contrast between the different reticuloendothelial organs and accumulate in the tumor within an hour of post-administration. ZnPcS4 and AlPcS4 offered little contrast in photoacoustic signals between the organs. PcS4 is a promising photoacoustic contrast agent and can be exploited as a photodiagnostic agent.

  6. The protein corona of circulating PEGylated liposomes.

    PubMed

    Palchetti, Sara; Colapicchioni, Valentina; Digiacomo, Luca; Caracciolo, Giulio; Pozzi, Daniela; Capriotti, Anna Laura; La Barbera, Giorgia; Laganà, Aldo

    2016-02-01

    Following systemic administration, liposomes are covered by a 'corona' of proteins, and preserving the surface functionality is challenging. Coating the liposome surface with polyethylene glycol (PEG) is the most widely used anti-opsonization strategy, but it cannot fully preclude protein adsorption. To date, protein binding has been studied following in vitro incubation to predict the fate of liposomes in vivo, while dynamic incubation mimicking in vivo conditions remains largely unexplored. The main aim of this investigation was to determine whether shear stress, produced by physiologically relevant dynamic flow, could influence the liposome-protein corona. The corona of circulating PEGylated liposome was thoroughly compared with that formed by incubation in vitro. Systematic comparison in terms of size, surface charge and quantitative composition was made by dynamic light scattering, microelectrophoresis and nano-liquid chromatography tandem mass spectrometry (nanoLC-MS/MS). Size of coronas formed under static vs. dynamic incubation did not appreciably differ from each other. On the other side, the corona of circulating liposomes was more negatively charged than its static counterpart. Of note, the variety of protein species in the corona formed in a dynamic flow was significantly wider. Collectively, these results demonstrated that the corona of circulating PEGylated liposomes can be considerably different from that formed in a static fluid. This seems to be a key factor to predict the biological activity of a liposomal formulation in a physiological environment.

  7. Methods for using redox liposome biosensors

    DOEpatents

    Cheng, Quan; Stevens, Raymond C.

    2002-01-01

    The present invention provides methods and compositions for detecting the presence of biologically-important analytes by using redox liposome biosensors. In particular, the present invention provides liposome/sol-gel electrodes suitable for the detection of a wide variety of organic molecules, including but not limited to bacterial toxins.

  8. Liposomal nanocapsules in food science and agriculture.

    PubMed

    Taylor, T Matthew; Davidson, P Michael; Bruce, Barry D; Weiss, Jochen

    2005-01-01

    Liposomes, spherical bilayer vesicles from dispersion of polar lipids in aqueous solvents, have been widely studied for their ability to act as drug delivery vehicles by shielding reactive or sensitive compounds prior to release. Liposome entrapment has been shown to stabilize encapsulated, bioactive materials against a range of environmental and chemical changes, including enzymatic and chemical modification, as well as buffering against extreme pH, temperature, and ionic strength changes. Liposomes have been especially useful to researchers in studies of various physiological processes as models of biological membranes in both eukaryotes and prokaryotes. Industrial applications include encapsulation of pharmaceuticals and therapeutics, cosmetics, anti-cancer and gene therapy drugs. In the food industry, liposomes have been used to deliver food flavors and nutrients and more recently have been investigated for their ability to incorporate food antimicrobials that could aid in the protection of food products against growth of spoilage and pathogenic microorganisms. In this review we briefly introduce key physicochemical properties of liposomes and review competing methods for liposome production. A survey of non-agricultural and food applications of liposomes are given. Finally, a detailed up-to-date summary of the emerging usage of liposomes in the food industry as delivery vehicles of nutrients, nutraceuticals, food additives, and food antimicrobials is provided.

  9. Transfer mechanism of temoporfin between liposomal membranes.

    PubMed

    Hefesha, Hossam; Loew, Stephan; Liu, Xiangli; May, Sylvio; Fahr, Alfred

    2011-03-30

    The transfer kinetics of temoporfin, a classic photosensitizer, was analyzed by investigating the influence of total lipid content, temperature, as well as charge, acyl chain length, and saturation of the lipids in donor vesicles using a mini ion exchange column technique. The obtained results are consistent with an apparent first order kinetics in which the transfer proceeds through both liposome collisions and through the aqueous phase. We present a corresponding theoretical model that accounts for the detailed distribution of drug molecules in donor and acceptor liposomes and predicts the transfer rates as a function of drug concentration and number of donor and acceptor liposomes. The experimentally observed transfer rates depended strongly on the temperature and comply with the Arrhenius equation. Thermodynamic calculations indicate the transfer process to be entropically controlled. In terms of the charge of donor liposomes, positively charged liposomes showed transfer rates faster than negatively charged liposomes whereas the maximum amount transferred was almost the same. A more rigid structure of the donor liposomes increases the transfer rate of temoporfin, which is caused by expelling the drug from the membrane interior, as proposed in former work. In summary, our combined theoretical/experimental approach offers a systematic way to study the mechanism of drug release from liposome-based delivery systems.

  10. Synthesis and characterization of monoisomeric 1,8,15,22-substituted (A3B and A2B2) phthalocyanines and phthalocyanine-fullerene dyads.

    PubMed

    Ranta, Jenni; Kumpulainen, Tatu; Lemmetyinen, Helge; Efimov, Alexander

    2010-08-01

    Synthesis and characterization of three phthalocyanine-fullerene (Pc-C(60)) dyads, corresponding monoisomeric phthalocyanines (Pc), and building blocks, phthalonitriles, are described. Six novel bisaryl phthalonitriles were prepared by the Suzuki-Miyaura coupling reaction from trifluoromethanesulfonic acid 2,3-dicyanophenyl ester and various oxaborolanes. Two phthalonitriles were selected for the synthesis of A(3)B- and A(2)B(2)-type phthalocyanines. Phthalonitrile 4 has a bulky 3,5-di-tert-butylphenyl substituent at the alpha-phthalo position, which forces only one regioisomer to form and greatly increases the solubility of phthalocyanine. Phthalonitrile 8 has a 3-phenylpropanol side chain at the alpha-position making further modifications of the side group possible. Synthesized monoisomeric A(3)B- and A(2)B(2)-type phthalocyanines are modified by attachment of malonic residues. Finally, fullerene is covalently linked to phthalocyanine with one or two malonic bridges to produce Pc-C(60) dyads. Due to the monoisomeric structure and increased solubility of phthalocyanines, the quality of NMR spectra of the compounds is enhanced significantly, making detailed NMR analysis of the structures possible. The synthesized dyads have different orientations of phthalocyanine and fullerene, which strongly influence the electron transfer (ET) from phthalocyanine to fullerene moiety. Fluorescence quenchings of the dyads were measured in both polar and nonpolar solvents, and in all cases, the quenching was more efficient in the polar environment. As expected, most efficient fluorescence quenching was observed for dyad 20b, with two linkers and phthalocyanine and fullerene in face-to-face orientation.

  11. Synthesis of an ABCD-Type Phthalocyanine by Intramolecular Cyclization Reaction.

    PubMed

    Chow, Sun Y S; Ng, Dennis K P

    2016-07-01

    Unsymmetrical phthalocyanines with a low symmetry can exhibit unique and intriguing properties that can facilitate their applications in certain disciplines. The synthesis of these compounds, however, has posed a great difficulty. A novel and unprecedented approach for phthalocyanine synthesis is reported that involves intramolecular cyclization of prelinked tetrakisphthalonitriles. By using this strategy, the first ABCD-type phthalocyanine has been prepared in 7.2% yield. PMID:27309120

  12. Synthesis of an ABCD-Type Phthalocyanine by Intramolecular Cyclization Reaction.

    PubMed

    Chow, Sun Y S; Ng, Dennis K P

    2016-07-01

    Unsymmetrical phthalocyanines with a low symmetry can exhibit unique and intriguing properties that can facilitate their applications in certain disciplines. The synthesis of these compounds, however, has posed a great difficulty. A novel and unprecedented approach for phthalocyanine synthesis is reported that involves intramolecular cyclization of prelinked tetrakisphthalonitriles. By using this strategy, the first ABCD-type phthalocyanine has been prepared in 7.2% yield.

  13. "Smart" liposomal nanocontainers in biology and medicine.

    PubMed

    Tarahovsky, Y S

    2010-07-01

    The perspectives of using liposomes for delivery of drugs to desired parts of the human body have been intensively investigated for more than 30 years. During this time many inventions have been suggested and different kinds of liposomal devices developed, and a number of them have reached the stages of preclinical or clinical trials. The latest techniques can be used to develop biocompatible nano-sized liposomal containers having some abilities of artificial intellect, such as the presence of sensory and responsive units. However, only a few have been clinically approved. Further improvements in this area depend on our knowledge of the interactions of drugs with the lipid bilayer of liposomes. Further studies on liposomal transport through the human body, their targeting of cells requiring therapeutic treatment, and finally, the development of techniques for controlled drug delivery to desired acceptors on cell surfaces or in cytoplasm are still required.

  14. Nonperipheral Tetrakis(dibutylamino)phthalocyanines. New Types of 1,8,15,22-Tetrakis(substituted)phthalocyanine Isomers.

    PubMed

    Chen, Yuxiang; Fang, Wenjuan; Wang, Kang; Liu, Wei; Jiang, Jianzhuang

    2016-09-19

    Cyclic tetramerization of 3-(dibutylamino)phthalonitrile in refluxing n-pentanol in the presence of magnesium pentanoate afforded the four regioisomer-containing nonperipheral 1,8-/11,15-/18,22-/25-tetrakis(dibutylamino)phthalocyaninato magnesium complexes with the 1,8,15,22-tetrakis(dibutylamino)phthalocyanine isomer Mg{Pc[α-N(C4H9)2]4-C4} (2). This, in combination with its much superior crystallinity over the remaining three isomers, renders the easy isolation of 2 only through two simple recrystallizations from THF and methanol. Treatment of 2 with trifluoroacetic acid induced the isolation of metal-free 1,8,15,22-tetrakis(dibutylamino)phthalocyanine, H2{Pc[α-N(C4H9)2]4-C4} (1), which further reacted with M(OAc)2·nH2O (M = Ni, Zn) in refluxing n-pentanol, giving the 1,8,15,22-tetrakis(dibutylamino)phthalocyaninato metal complexes M{Pc[α-N(C4H9)2]4-C4} (M = Ni (3), Zn (4)). The full series of four 1,8,15,22-tetrakis(dibutylamino)phthalocyanine isomeric compounds have been characterized by a series of spectroscopic methods and single-crystal X-ray diffraction analyses. Obviously, the present result provides a simple and effective pathway for the synthesis and isolation of novel 1,8,15,22-tetrakis(dibutylamino)phthalocyanine isomeric derivatives, providing one step forward toward completing bis(alkyl)amino-incorporated phthalocyanine species.

  15. Nonperipheral Tetrakis(dibutylamino)phthalocyanines. New Types of 1,8,15,22-Tetrakis(substituted)phthalocyanine Isomers.

    PubMed

    Chen, Yuxiang; Fang, Wenjuan; Wang, Kang; Liu, Wei; Jiang, Jianzhuang

    2016-09-19

    Cyclic tetramerization of 3-(dibutylamino)phthalonitrile in refluxing n-pentanol in the presence of magnesium pentanoate afforded the four regioisomer-containing nonperipheral 1,8-/11,15-/18,22-/25-tetrakis(dibutylamino)phthalocyaninato magnesium complexes with the 1,8,15,22-tetrakis(dibutylamino)phthalocyanine isomer Mg{Pc[α-N(C4H9)2]4-C4} (2). This, in combination with its much superior crystallinity over the remaining three isomers, renders the easy isolation of 2 only through two simple recrystallizations from THF and methanol. Treatment of 2 with trifluoroacetic acid induced the isolation of metal-free 1,8,15,22-tetrakis(dibutylamino)phthalocyanine, H2{Pc[α-N(C4H9)2]4-C4} (1), which further reacted with M(OAc)2·nH2O (M = Ni, Zn) in refluxing n-pentanol, giving the 1,8,15,22-tetrakis(dibutylamino)phthalocyaninato metal complexes M{Pc[α-N(C4H9)2]4-C4} (M = Ni (3), Zn (4)). The full series of four 1,8,15,22-tetrakis(dibutylamino)phthalocyanine isomeric compounds have been characterized by a series of spectroscopic methods and single-crystal X-ray diffraction analyses. Obviously, the present result provides a simple and effective pathway for the synthesis and isolation of novel 1,8,15,22-tetrakis(dibutylamino)phthalocyanine isomeric derivatives, providing one step forward toward completing bis(alkyl)amino-incorporated phthalocyanine species. PMID:27580413

  16. Pharmacokinetics of temoporfin-loaded liposome formulations: correlation of liposome and temoporfin blood concentration.

    PubMed

    Decker, Christiane; Schubert, Harald; May, Sylvio; Fahr, Alfred

    2013-03-28

    Liposomal formulations of the highly hydrophobic photosensitizer temoporfin were developed in order to overcome solubility-related problems associated with the current therapy scheme. We have incorporated temoporfin into liposomes of varying membrane composition, cholesterol content, and vesicle size. Specifically, two phosphatidyl oligoglycerols were compared to PEG2000-DSPE with respect to the ability to prolong circulation half life of the liposomal carrier. We measured the resulting pharmacokinetic profile of the liposomal carrier and the incorporated temoporfin in a rat model employing a radioactive lipid label and (14)C-temoporfin. The data for the removal of liposomes and temoporfin were analyzed in terms of classical pharmacokinetic theory assuming a two-compartment model. This model, however, does not allow in a straightforward manner to distinguish between temoporfin eliminated together with the liposomal carrier and temoporfin that is first transferred to other blood components (e. g. plasma proteins) before being eliminated from the blood. We therefore additionally analyzed the data based on two separate one-compartment models for the liposomes and temoporfin. The model yields the ratio of the rate constant of temoporfin elimination together with the liposomal carrier and the rate constant of temoporfin elimination following the transfer to e. g. plasma proteins. Our analysis using this model demonstrates that a fraction of temoporfin is released from the liposomes prior to being eliminated from the blood. In case of unmodified liposomes this temoporfin release was observed to increase with decreasing bilayer fluidity, indicating an accelerated temoporfin transfer from gel-phase liposomes to e. g. plasma proteins. Interestingly, liposomes carrying either one of the three investigated surface-modifying agents did not adhere to the tendencies observed for unmodified liposomes. Although surface-modified liposomes exhibited improved pharmacokinetic

  17. Investigation of the Qx -Qy Equilibrium in a Metal-Free Phthalocyanine.

    PubMed

    Baeten, Yannick; Fron, Eduard; Ruzié, Christian; Geerts, Yves Henri; Van Der Auweraer, Mark

    2015-12-21

    Phthalocyanines (Pcs) have attracted a lot of interest as small molecules for organic electronics. However, some excited-state properties of metal-free phthalocyanines, as for example, the dynamics of the transition between the nondegenerate Qx and Qy states in a metal-free phthalocyanine, have not been fully established. This effect results in a blue-shifted shoulder with low intensity in the Pc fluorescence spectrum. This shoulder was suggested to be related to emission from the more energetic Qy state. By using ultrafast femtosecond transient absorption, we have found a clear equilibrium between the Qx and Qy state of metal-free phthalocyanines in solution.

  18. Investigation of the Qx -Qy Equilibrium in a Metal-Free Phthalocyanine.

    PubMed

    Baeten, Yannick; Fron, Eduard; Ruzié, Christian; Geerts, Yves Henri; Van Der Auweraer, Mark

    2015-12-21

    Phthalocyanines (Pcs) have attracted a lot of interest as small molecules for organic electronics. However, some excited-state properties of metal-free phthalocyanines, as for example, the dynamics of the transition between the nondegenerate Qx and Qy states in a metal-free phthalocyanine, have not been fully established. This effect results in a blue-shifted shoulder with low intensity in the Pc fluorescence spectrum. This shoulder was suggested to be related to emission from the more energetic Qy state. By using ultrafast femtosecond transient absorption, we have found a clear equilibrium between the Qx and Qy state of metal-free phthalocyanines in solution. PMID:26346288

  19. Topical and mucosal liposomes for vaccine delivery.

    PubMed

    Romero, Eder Lilia; Morilla, Maria Jose

    2011-01-01

    Mucosal (and in minor extent transcutanous) stimulation can induce local or distant mucosa secretory IgA. Liposomes and other vesicles as mucosal and transcutaneous adjuvants are attractive alternatives to parenteral vaccination. Liposomes can be massively produced under good manufacturing practices and stored for long periods, at high antigen/vesicle mass ratios. However, their uptake by antigen-presenting cells (APC) at the inductive sites remains as a major challenge. As neurotoxicity is a major concern in intranasal delivery, complexes between archaeosomes and calcium as well as cationic liposomes complexed with plasmids encoding for antigenic proteins could safely elicit secretory and systemic antigen-specific immune responses. Oral bilosomes generate intense immune responses that remain to be tested against challenge, but the admixing with toxins or derivatives is mandatory to reduce the amount of antigen. Most of the current experimental designs, however, underestimate the mucus blanket 100- to 1000-fold thicker than a 100-nm diameter liposome, which has first to be penetrated to access the underlying M cells. Overall, designing mucoadhesive chemoenzymatic resistant liposomes, or selectively targeted to M cells, has produced less relevant results than tailoring the liposomes to make them mucus penetrating. Opposing, the nearly 10 µm thickness stratum corneum interposed between liposomes and underlying APC can be surpassed by ultradeformable liposomes (UDL), with lipid matrices that penetrate up to the limit with the viable epidermis. UDL made of phospholipids and detergents, proved to be better transfection agents than conventional liposomes and niosomes, without the toxicity of ethosomes, in the absence of classical immunomodulators. PMID:21360692

  20. Possibility of heat sterilization of liposomes.

    PubMed

    Kikuchi, H; Carlsson, A; Yachi, K; Hirota, S

    1991-04-01

    Several kinds of liposomes were sterilized at 121 degrees C for 20 min. They tended to aggregate after heat sterilization (HS) in saline, while no aggregation was observed in an isotonized sugar or polyol solution. The dispersions containing egg phosphatidylcholine (EggPC) with a high peroxide value (POV) turned slightly yellowish after HS. This color change was prevented by using EggPC with a low POV, hydrogenated EggPC (H-EggPC) or dipalmitoylphosphatidylcholine (DPPC). Nitrogen gas bubbling at neutral pH also prevented the color change, but vitamin E did not. The particle size of the EggPC liposomes extruded through a 0.4 micron membrane filter did not change significantly after HS, whereas the H-EggPC or DPPC liposomes extruded through a 0.8 micron membrane filter tended to be reduced in size. On this change the type of medium had a considerable influence. The anionic 6-carboxyfluorescein leaked from the negatively charged liposomes (EggPC/cholesterol (Chol)/egg phosphatidylglycerol) during HS, while no leakage was observed from the positively charged liposomes (EggPC/Chol/stearylamine) not only during HS but also during a long period of storage. It was suggested that sterilization of liposomes by heating was practicable as well as that by filtration, if the liposomes were prepared as follows: the charged liposomes made of lipids with low POV's were dispersed in a sugar or polyol solution adjusted to nearly pH 6.5, where the amount of dissolved oxygen was minimized. An ionic water-soluble drug had to be encapsulated in the oppositely charged liposomes.

  1. Solution-Processable Silicon Phthalocyanines in Electroluminescent and Photovoltaic Devices.

    PubMed

    Zysman-Colman, Eli; Ghosh, Sanjay S; Xie, Guohua; Varghese, Shinto; Chowdhury, Mithun; Sharma, Nidhi; Cordes, David B; Slawin, Alexandra M Z; Samuel, Ifor D W

    2016-04-13

    Phthalocyanines and their main group and metal complexes are important classes of organic semiconductor materials but are usually highly insoluble and so frequently need to be processed by vacuum deposition in devices. We report two highly soluble silicon phthalocyanine (SiPc) diester compounds and demonstrate their potential as organic semiconductor materials. Near-infrared (λ(EL) = 698-709 nm) solution-processed organic light-emitting diodes (OLEDs) were fabricated and exhibited external quantum efficiencies (EQEs) of up to 1.4%. Binary bulk heterojunction solar cells employing P3HT or PTB7 as the donor and the SiPc as the acceptor provided power conversion efficiencies (PCE) of up to 2.7% under simulated solar illumination. Our results show that soluble SiPcs are promising materials for organic electronics.

  2. Solution-Processable Silicon Phthalocyanines in Electroluminescent and Photovoltaic Devices

    PubMed Central

    2016-01-01

    Phthalocyanines and their main group and metal complexes are important classes of organic semiconductor materials but are usually highly insoluble and so frequently need to be processed by vacuum deposition in devices. We report two highly soluble silicon phthalocyanine (SiPc) diester compounds and demonstrate their potential as organic semiconductor materials. Near-infrared (λEL = 698–709 nm) solution-processed organic light-emitting diodes (OLEDs) were fabricated and exhibited external quantum efficiencies (EQEs) of up to 1.4%. Binary bulk heterojunction solar cells employing P3HT or PTB7 as the donor and the SiPc as the acceptor provided power conversion efficiencies (PCE) of up to 2.7% under simulated solar illumination. Our results show that soluble SiPcs are promising materials for organic electronics. PMID:26990151

  3. Liposome-encapsulated actinomycin for cancer chemotherapy

    DOEpatents

    Rahman, Yueh-Erh; Cerny, Elizabeth A.

    1976-01-01

    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 penetrates into the tumor cells where the drug is slowly released and induces degeneration and death of the tumor cells, while any toxicity to the host body is reduced. Liposome encapsulation of actinomycin D has been found to be particularly effective in treating cancerous abdominal tumors, while drastically reducing the toxicity of actinomycin D to the host.

  4. The production of copper phthalocyanine and/or its derivatives

    NASA Technical Reports Server (NTRS)

    Segawa, T.; Matsuzaki, K.; Sawada, H.; Ninomiya, R.; Suyama, M.

    1984-01-01

    This document discusses the production of copper phthalocyanine and/or its derivatives, which are useful for dye pigments. The method described uses urea, a copper compound and/or a catalyst which have been suspended in an inert reaction medium. The copper compound, catalyst and urea fused and the reaction is performed by using the obtained fusion. The advantages of the invention are listed.

  5. Nanostructured copper phthalocyanine-sensitized multiwall carbon nanotube films.

    PubMed

    Hatton, Ross A; Blanchard, Nicholas P; Stolojan, Vlad; Miller, Anthony J; Silva, S Ravi P

    2007-05-22

    We report a detailed study of the interaction between surface-oxidized multiwall carbon nanotubes (o-MWCNTs) and the molecular semiconductor tetrasulfonate copper phthalocyanine (TS-CuPc). Concentrated dispersions of o-MWCNT in aqueous solutions of TS-CuPc are stable toward nanotube flocculation and exhibit spontaneous nanostructuring upon rapid drying. In addition to hydrogen-bonding interactions, the compatibility between the two components is shown to result from a ground-state charge-transfer interaction with partial charge transfer from o-MWCNT to TS-CuPc molecules orientated such that the plane of the macrocycle is parallel to the nanotube surface. The electronegativity of TS-CuPc as compared to unsubsubtituted copper phthalocyanine is shown to result from the electron-withdrawing character of the sulfonate substituents, which increase the molecular ionization potential and promote cofacial molecular aggregation upon drying. Upon spin casting to form uniform thin films, the experimental evidence is consistent with an o-MWCNT scaffold decorated with phthalocyanine molecules self-assembled into extended aggregates reminiscent of 1-D linearly stacked phthalocyanine polymers. Remarkably, this self-organization occurs in a fraction of a second during the spin-coating process. To demonstrate the potential utility of this hybrid material, it is successfully incorporated into a model organic photovoltaic cell at the interface between a poly(3-hexylthiophene):[6,6]-phenyl-C61 butyric acid methyl ester bulk heterojunction layer and an indium-tin oxide-coated glass electrode to increase the light-harvesting capability of the device and facilitate hole extraction. The resulting enhancement in power conversion efficiency is rationalized in terms of the electronic, optical, and morphological properties of the nanostructured thin film. PMID:17439261

  6. Origin of electronic transport of lithium phthalocyanine iodine crystal

    SciTech Connect

    Koike, Noritake; Oda, Masato; Shinozuka, Yuzo

    2013-12-04

    The electronic structures of Lithium Phthalocyanine Iodine are investigated using density functional theory. Comparing the band structures of several model crystals, the metallic conductivity of highly doped LiPcI{sub x} can be explained by the band of doped iodine. These results reveal that there is a new mechanism for electronic transport of doped organic semiconductors that the dopant band plays the main role.

  7. Metal phthalocyanine intermediates for the preparation of polymers

    NASA Technical Reports Server (NTRS)

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

    1985-01-01

    Metal 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. These tetracarboxylic acids are then polymerized by heat to sheet polymers which have superior heat and oxidation resistance. The metal is preferably a divalent metal having an atomic radius close to 1.35A.

  8. Nanostructured copper phthalocyanine-sensitized multiwall carbon nanotube films.

    PubMed

    Hatton, Ross A; Blanchard, Nicholas P; Stolojan, Vlad; Miller, Anthony J; Silva, S Ravi P

    2007-05-22

    We report a detailed study of the interaction between surface-oxidized multiwall carbon nanotubes (o-MWCNTs) and the molecular semiconductor tetrasulfonate copper phthalocyanine (TS-CuPc). Concentrated dispersions of o-MWCNT in aqueous solutions of TS-CuPc are stable toward nanotube flocculation and exhibit spontaneous nanostructuring upon rapid drying. In addition to hydrogen-bonding interactions, the compatibility between the two components is shown to result from a ground-state charge-transfer interaction with partial charge transfer from o-MWCNT to TS-CuPc molecules orientated such that the plane of the macrocycle is parallel to the nanotube surface. The electronegativity of TS-CuPc as compared to unsubsubtituted copper phthalocyanine is shown to result from the electron-withdrawing character of the sulfonate substituents, which increase the molecular ionization potential and promote cofacial molecular aggregation upon drying. Upon spin casting to form uniform thin films, the experimental evidence is consistent with an o-MWCNT scaffold decorated with phthalocyanine molecules self-assembled into extended aggregates reminiscent of 1-D linearly stacked phthalocyanine polymers. Remarkably, this self-organization occurs in a fraction of a second during the spin-coating process. To demonstrate the potential utility of this hybrid material, it is successfully incorporated into a model organic photovoltaic cell at the interface between a poly(3-hexylthiophene):[6,6]-phenyl-C61 butyric acid methyl ester bulk heterojunction layer and an indium-tin oxide-coated glass electrode to increase the light-harvesting capability of the device and facilitate hole extraction. The resulting enhancement in power conversion efficiency is rationalized in terms of the electronic, optical, and morphological properties of the nanostructured thin film.

  9. Modification of symmetrically substituted phthalocyanines using click chemistry: phthalocyanine nanostructures by nanoimprint lithography.

    PubMed

    Chen, Xiaochun; Thomas, Jayan; Gangopadhyay, Palash; Norwood, Robert A; Peyghambarian, N; McGrath, Dominic V

    2009-09-30

    Phthalocyanines (Pcs) are commonly applied to advanced technologies such as optical limiting, photodynamic therapy (PDT), organic field-effect transistors (OFETs), and organic photovoltaic (OPV) devices, where they are used as the p-type layer. An approach to Pc structural diversity and the incorporation of a functional group that allows fabrication of solvent resistant Pc nanostructures formed by using a newly developed nanoimprint by melt processing (NIMP) technique, a variant of standard nanoimprint lithography (NIL), is reported. Copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC), a click chemistry reaction, serves as an approach to structural diversity in Pc macrocycles. We have prepared octaalkynyl Pc 1b and have modified this Pc using the CuAAC reaction to yield four Pc derivatives 5a-5d with different peripheral substituents on the macrocycle. One of these derivatives, 5c, has photo-cross-linkable cinnamate residues, and we have demonstrated the fabrication of robust cross-linked photopatterned and imprinted nanostructures from this material.

  10. Phthalocyanines And Their Sulfonated Derivatives As Photosensitizers In Photodynamic Therapy.

    NASA Astrophysics Data System (ADS)

    Riesz, Peter; Krishna, C. Murali

    1988-02-01

    Photodynamic therapy (PDT) of human tumors with hematoporphyrin derivative (HpD) has achieved encouraging results. However, HpD is a complex mixture whose composition varies in different preparations and with time of storage. The future promise of PDT for cancer treatment depends on the development of new chemically defined sensitizers which absorb more strongly than HpD in the 600-800 nm region. A shift to higher wavelengths is desirable since it allows increased light penetration in human tissues. In vivo, these sensitizers should be non-toxic, localize selectively in tumors and generate cytotoxic species upon illumination with a high quantum yield. These damaging species may be singlet oxygen (1O2) produced by the transfer of energy from the triplet state of the sensitizer to oxygen (Type II) or superoxide anion radicals formed by electron transfer to oxygen or substrate radicals generated by electron or hydrogen transfer directly from the sensitizer (Type I). The recent work of several groups indicating that phthalocyanines and their water soluble derivatives are promising candidates for PDT is reviewed. The photophysics, photochemistry, photosensitized killing of cultured mammalian cells and the use for in vivo photodynamic therapy of phthalocyanines is outlined. Our studies of the post-illumination photohemolysis of human red blood cells as a model system for membrane photomodification sensitized by phthalocyanine sulfonates are consistent with the predominant role of 1O2 as the damaging species.

  11. Inverted methoxypyridinium phthalocyanines for PDI of pathogenic bacteria.

    PubMed

    Lourenço, Leandro M O; Sousa, Andreina; Gomes, Maria C; Faustino, Maria A F; Almeida, Adelaide; Silva, Artur M S; Neves, Maria G P M S; Cavaleiro, José A S; Cunha, Ângela; Tomé, João P C

    2015-10-01

    Phthalocyanines (Pc) are photoactive molecules that can absorb and emit light in a large range of the UV-Vis spectrum with recognized potential for medical applications. Considering the biomedical applications an important limitation of these compounds is their low solubility in water. The use of suitable pyridinium groups on Pc is a good strategy to solve this drawback and to make them more effective to photoinactivate Gram-negative bacteria via a photodynamic inactivation (PDI) approach. Herein, an easy synthetic access to obtain inverted tetra- and octa-methoxypyridinium phthalocyanines (compounds 5 and 6) and also their efficiency to photoinactivate a recombinant bioluminescent strain of Escherichia coli is described. The obtained results were compared with the ones obtained when more conventional thiopyridinium phthalocyanines (compounds 7 and 8) were used. This innovative study comparing thiopyridinium and inverted methoxypyridinium moieties on cationic Pc is reported for the first time taking into account the efficiency of singlet oxygen ((1)O2) generation, water solubility and uptake properties.

  12. Phthalocyanine-Based Molecularly Imprinted Polymers as Nucleoside Receptors

    PubMed Central

    Longo, Luigia; Vasapollo, Giuseppe

    2008-01-01

    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. PMID:18288245

  13. An acid-cleavable phthalocyanine tetramer as an activatable photosensitiser for photodynamic therapy.

    PubMed

    Chow, Sun Y S; Lo, Pui-Chi; Ng, Dennis K P

    2016-08-16

    An acetal-linked self-quenched zinc(ii) phthalocyanine tetramer has been prepared. In an acidic environment in phosphate buffered saline or inside tumour cells, the phthalocyanine units of the tetramer are separated thereby restoring the fluorescence emission and singlet oxygen production. This response enables this compound to serve as a promising activatable photosensitiser for photodynamic therapy. PMID:27396392

  14. Copper phthalocyanine-based CMPs with various internal structures and functionalities.

    PubMed

    Ding, Xuesong; Han, Bao-Hang

    2015-08-18

    Several kinds of copper phthalocyanine-based conjugated microporous polymers have been synthesized, which present enhanced long-wavelength photon absorption capability and high efficiency for singlet oxygen generation under low energy light irradiation. This strategy opens a facile avenue towards expanding the scope of phthalocyanine-based porous materials with various internal structures and functionalities.

  15. Copper phthalocyanine-based CMPs with various internal structures and functionalities.

    PubMed

    Ding, Xuesong; Han, Bao-Hang

    2015-08-18

    Several kinds of copper phthalocyanine-based conjugated microporous polymers have been synthesized, which present enhanced long-wavelength photon absorption capability and high efficiency for singlet oxygen generation under low energy light irradiation. This strategy opens a facile avenue towards expanding the scope of phthalocyanine-based porous materials with various internal structures and functionalities. PMID:26166552

  16. Optical recording properties of phthalocyanine copper as a write-once read-many recording medium

    SciTech Connect

    Chen, Q.; Gu, D.; Shu, J.; Tang, X.; Gan, F.

    1994-12-31

    The phthalocyanine compounds have received considerable attention because of their good thermal and chemical stability which ensure a long storage life and high readout times as optical storage media. In this paper, the optical spectra and the complex refractive index of phthalocyanine copper (CuPc) have been studied. The optical recording performances of multilayer films are reported.

  17. Heterogeneous PNA Liposomes for Gene Delivery

    NASA Astrophysics Data System (ADS)

    Marques, Bruno; Morfesis, Ana; Yoon, Diana; Schneider, James

    2002-03-01

    To circumvent complications of DNA adsorption onto cationic liposomes (i.e. structural reorganization, cytotoxicity), we have developed a liposomal system that binds genetic material via hydrogen bonding interactions. These liposomes contain surfactants linked to peptide nucleic acid (PNA), a synthetic DNA mimic with unique DNA-binding properties. We target multiple short regions of the DNA strand, sequestering the DNA from nuclease in solution, to protect it from nuclease digestion. Here, we present zeta potential measurements quantifying the extent of PNA incorporation in the liposomes, as well as the extent of DNA binding and nuclease activity under various conditions for mixtures of di- and trinucleotide PNA. We also discuss our attempts to identify the minimal PNA oligomer length to achieve stable binding and sequence specificity.

  18. Enhancement of NO2 gas detection in hybrid silver nanoparticles-phthalocyanine thin films

    NASA Astrophysics Data System (ADS)

    Zasedatelev, A. V.; Krichevsky, D. M.; Zelenskiy, Yu M.; Tolbin, A. Yu; Krasovskii, V. I.; Karpo, A. B.; Tomilova, L. G.

    2016-08-01

    Phthalocyanine-functionalized plasmonic sensing systems are typically based on Kretschmann configuration. Such scheme of detection utilizes spectral or angular modulation of reflected light, which is induced by surface plasmon's excitation in the metal film on prism. Phthalocyanine's layer plays a role of analyte adsorber. In present paper we offer another approach to phthalocyanine-plasmonic sensing, where both local surface plasmon resonance and optical absorption of phthalocyanines are simultaneously detected. Hybrid Ag nanoparticles (AgNps) - low symmetrical A3B zinc phthalocyanine (ZnPc) thin films were prepared, and their NO2 gas sensitive properties were examined. Since the plasmon resonance of AgNps was properly tuned to charge-transfer band of ZnPc-NO2 complex, we found out more than two-fold increase of the optical response to NO2 exposure in AgNps-ZnPc thin films compared to ZnPc films without AgNps.

  19. Surface fractals in liposome aggregation.

    PubMed

    Roldán-Vargas, Sándalo; Barnadas-Rodríguez, Ramon; Quesada-Pérez, Manuel; Estelrich, Joan; Callejas-Fernández, José

    2009-01-01

    In this work, the aggregation of charged liposomes induced by magnesium is investigated. Static and dynamic light scattering, Fourier-transform infrared spectroscopy, and cryotransmission electron microscopy are used as experimental techniques. In particular, multiple intracluster scattering is reduced to a negligible amount using a cross-correlation light scattering scheme. The analysis of the cluster structure, probed by means of static light scattering, reveals an evolution from surface fractals to mass fractals with increasing magnesium concentration. Cryotransmission electron microscopy micrographs of the aggregates are consistent with this interpretation. In addition, a comparative analysis of these results with those previously reported in the presence of calcium suggests that the different hydration energy between lipid vesicles when these divalent cations are present plays a fundamental role in the cluster morphology. This suggestion is also supported by infrared spectroscopy data. The kinetics of the aggregation processes is also analyzed through the time evolution of the mean diffusion coefficient of the aggregates. PMID:19257067

  20. Surface fractals in liposome aggregation.

    PubMed

    Roldán-Vargas, Sándalo; Barnadas-Rodríguez, Ramon; Quesada-Pérez, Manuel; Estelrich, Joan; Callejas-Fernández, José

    2009-01-01

    In this work, the aggregation of charged liposomes induced by magnesium is investigated. Static and dynamic light scattering, Fourier-transform infrared spectroscopy, and cryotransmission electron microscopy are used as experimental techniques. In particular, multiple intracluster scattering is reduced to a negligible amount using a cross-correlation light scattering scheme. The analysis of the cluster structure, probed by means of static light scattering, reveals an evolution from surface fractals to mass fractals with increasing magnesium concentration. Cryotransmission electron microscopy micrographs of the aggregates are consistent with this interpretation. In addition, a comparative analysis of these results with those previously reported in the presence of calcium suggests that the different hydration energy between lipid vesicles when these divalent cations are present plays a fundamental role in the cluster morphology. This suggestion is also supported by infrared spectroscopy data. The kinetics of the aggregation processes is also analyzed through the time evolution of the mean diffusion coefficient of the aggregates.

  1. Poly(ethylene glycol) on the liposome surface: on the mechanism of polymer-coated liposome longevity.

    PubMed

    Torchilin, V P; Omelyanenko, V G; Papisov, M I; Bogdanov, A A; Trubetskoy, V S; Herron, J N; Gentry, C A

    1994-10-12

    The hypothetical model is built explaining the molecular mechanism of protective action of poly(ethylene glycol) on liposomes in vivo. The protective layer of the polymer on the liposome surface is considered as a statistical 'cloud' of polymer possible conformations in solution. Computer simulation was used to demonstrate that relatively a small number of liposome-grafted molecules of hydrophilic and flexible polymer can create a dense protective conformational cloud over the liposome surface preventing opsonizing protein molecules from contacting liposome. A more rigid polymer fails to form this dense protective cloud, even when hydrophilic. Computer simulation was also used to reveal possible heterogeneity of reactive sites on a polymer-coated liposome surface, and to estimate the optimal polymer-to-lipid ratio for efficient liposome protection. Experiments have been performed with the quenching of liposome-associated fluorescent label (nitrobenzoxadiazole or fluorescein) with protein (rhodamine-ovalbumin or anti-fluorescein antibody) from solution. It was shown that poly(ethylene glycol) grafting to liposomes hinders protein interaction with the liposome surface, whereas liposome-grafted dextran (more rigid polymer) in similar quantities does not affect protein-liposome interaction. Highly-reactive and low-reactive populations of chemically identical reactive sites have been found on polymer-coated liposomes. Experimental data satisfactory confirm the suggested mechanism for the longevity of polymer-modified liposome.

  2. Octanol-assisted liposome assembly on chip

    PubMed Central

    Deshpande, Siddharth; Caspi, Yaron; Meijering, Anna E. C.; Dekker, Cees

    2016-01-01

    Liposomes are versatile supramolecular assemblies widely used in basic and applied sciences. Here we present a novel microfluidics-based method, octanol-assisted liposome assembly (OLA), to form monodisperse, cell-sized (5–20 μm), unilamellar liposomes with excellent encapsulation efficiency. Akin to bubble blowing, an inner aqueous phase and a surrounding lipid-carrying 1-octanol phase is pinched off by outer fluid streams. Such hydrodynamic flow focusing results in double-emulsion droplets that spontaneously develop a side-connected 1-octanol pocket. Owing to interfacial energy minimization, the pocket splits off to yield fully assembled solvent-free liposomes within minutes. This solves the long-standing fundamental problem of prolonged presence of residual oil in the liposome bilayer. We demonstrate the unilamellarity of liposomes with functional α-haemolysin protein pores in the membrane and validate the biocompatibility by inner leaflet localization of bacterial divisome proteins (FtsZ and ZipA). OLA offers a versatile platform for future analytical tools, delivery systems, nanoreactors and synthetic cells. PMID:26794442

  3. Plasmon resonant liposomes for controlled drug delivery

    NASA Astrophysics Data System (ADS)

    Knights-Mitchell, Shellie S.; Romanowski, Marek

    2015-03-01

    Nanotechnology use in drug delivery promotes a reduction in systemic toxicity, improved pharmacokinetics, and better drug bioavailability. Liposomes continue to be extensively researched as drug delivery systems (DDS) with formulations such as Doxil® and Ambisome® approved by FDA and successfully marketed in the United States. However, the limited ability to precisely control release of active ingredients from these vesicles continues to challenge the broad implementation of this technology. Moreover, the full potential of the carrier to sequester drugs until it can reach its intended target has yet to be realized. Here, we describe a liposomal DDS that releases therapeutic doses of an anticancer drug in response to external stimulus. Earlier, we introduced degradable plasmon resonant liposomes. These constructs, obtained by reducing gold on the liposome surface, facilitate spatial and temporal release of drugs upon laser light illumination that ultimately induces an increase in temperature. In this work, plasmon resonant liposomes have been developed to stably encapsulate and retain doxorubicin at physiological conditions represented by isotonic saline at 37o C and pH 7.4. Subsequently, they are stimulated to release contents either by a 5o C increase in temperature or by laser illumination (760 nm and 88 mW/cm2 power density). Successful development of degradable plasmon resonant liposomes responsive to near-infrared light or moderate hyperthermia can provide a new delivery method for multiple lipophilic and hydrophilic drugs with pharmacokinetic profiles that limit clinical utility.

  4. Octanol-assisted liposome assembly on chip

    NASA Astrophysics Data System (ADS)

    Deshpande, Siddharth; Caspi, Yaron; Meijering, Anna E. C.; Dekker, Cees

    2016-01-01

    Liposomes are versatile supramolecular assemblies widely used in basic and applied sciences. Here we present a novel microfluidics-based method, octanol-assisted liposome assembly (OLA), to form monodisperse, cell-sized (5-20 μm), unilamellar liposomes with excellent encapsulation efficiency. Akin to bubble blowing, an inner aqueous phase and a surrounding lipid-carrying 1-octanol phase is pinched off by outer fluid streams. Such hydrodynamic flow focusing results in double-emulsion droplets that spontaneously develop a side-connected 1-octanol pocket. Owing to interfacial energy minimization, the pocket splits off to yield fully assembled solvent-free liposomes within minutes. This solves the long-standing fundamental problem of prolonged presence of residual oil in the liposome bilayer. We demonstrate the unilamellarity of liposomes with functional α-haemolysin protein pores in the membrane and validate the biocompatibility by inner leaflet localization of bacterial divisome proteins (FtsZ and ZipA). OLA offers a versatile platform for future analytical tools, delivery systems, nanoreactors and synthetic cells.

  5. Octanol-assisted liposome assembly on chip.

    PubMed

    Deshpande, Siddharth; Caspi, Yaron; Meijering, Anna E C; Dekker, Cees

    2016-01-01

    Liposomes are versatile supramolecular assemblies widely used in basic and applied sciences. Here we present a novel microfluidics-based method, octanol-assisted liposome assembly (OLA), to form monodisperse, cell-sized (5-20 μm), unilamellar liposomes with excellent encapsulation efficiency. Akin to bubble blowing, an inner aqueous phase and a surrounding lipid-carrying 1-octanol phase is pinched off by outer fluid streams. Such hydrodynamic flow focusing results in double-emulsion droplets that spontaneously develop a side-connected 1-octanol pocket. Owing to interfacial energy minimization, the pocket splits off to yield fully assembled solvent-free liposomes within minutes. This solves the long-standing fundamental problem of prolonged presence of residual oil in the liposome bilayer. We demonstrate the unilamellarity of liposomes with functional α-haemolysin protein pores in the membrane and validate the biocompatibility by inner leaflet localization of bacterial divisome proteins (FtsZ and ZipA). OLA offers a versatile platform for future analytical tools, delivery systems, nanoreactors and synthetic cells. PMID:26794442

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

    NASA Astrophysics Data System (ADS)

    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

    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 5μm 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 2θ=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 1.3~2.0μm wavelength range peaked at ca. 1.75μm, indicating the important potential application value of phthalocyanine gadolinium in the field of organic infrared optoelectronics.

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

    PubMed

    Biyiklioglu, Zekeriya; Bas, Huseyin; Alp, Hakan

    2015-08-21

    A novel series of axially disubstituted silicon(iv) phthalocyanines bearing electropolymerizable ligands were designed and synthesized for the first time. The silicon(iv) phthalocyanines were characterized by various spectroscopic techniques as well as elemental analysis. The aggregation behavior of the SiPcs were examined in different solvents and at different concentrations in chloroform. In all the studied solvents and concentrations, the SiPcs were non-aggregated. The thermal behavior of the silicon(iv) phthalocyanines was also studied. The electropolymerization properties of the silicon(iv) phthalocyanines were investigated by cyclic and square wave voltammetry. This study is the first example of the electropolymerization of axially disubstituted silicon phthalocyanines. The type of axial ligand on the phthalocyanine ring did not show any effect on the absorption and thermal properties but influenced the electropolymerization of the phthalocyanines.

  8. [Assemble of magnetic nanoparticles into the structure of cisplatin liposome].

    PubMed

    Wang, Lu; Yang, Cai-qin; Wang, Jing

    2011-05-01

    Effects of different procedures of magnetic nanoparticles into the liposome structure on the distribution of magnetic particles in the liposome were investigated. Magnetic liposomes with high-encapsulating rate of cisplatin (CDDP) were obtained. Fe3O4 magnetic nanoparticles which was modified by organic functional group on surface was synthesized by an one-step modified hydrothermal method. The CDDP magnetic liposomes were prepared by a film scattering-ultrasonic technique and the concentrations of CDDP in the liposomes were measured by graphite furnace atomic absorbance spectroscopy. Magnetic liposomes with different microstructure were prepared by the two different procedures, where the magnetic particles were combined with phospholipid before the film preparation to form liposome in procedure I, and drug solution and the magnetic particles were mixed before hydrating the lipids film to form liposome in procedure II. The liposome structure was observed by transmission electron microscope (TEM). The CDDP magnetic liposomes were prepared by the optimized method which was selected by orthogonal test. Encapsulation rate of the magnetic particles distributed in the phospholipid bilayer through the procedure I was 34.90%. While liposome, produced by the procedure II technique, contained magnetic particles in the interior aqueous compartment, which encapsulation rate was 28.34%. Encapsulation rates of both I and II were higher than that of conventional liposome. The release profile of all the three different liposomes in vitro fitted with a first-order equation. Because of distribution of magnetic particles in the phospholipid bilayer, the skeleton of phospholipid bilayer was changed. The releasing tl/2 of magnetic liposomes produced by the procedure I technique is 9 h, which is shorter than that of the other two liposomes. Assemble of magnetic nanoparticles into the structure of liposome was succeeded by the procedure I, which showed superiority than by procedure II

  9. Dendritic Cells Stimulated by Cationic Liposomes.

    PubMed

    Vitor, Micaela Tamara; Bergami-Santos, Patrícia Cruz; Cruz, Karen Steponavicius Piedade; Pinho, Mariana Pereira; Barbuto, José Alexandre Marzagão; De La Torre, Lucimara Gaziola

    2016-01-01

    Immunotherapy of cancer aims to harness the immune system to detect and destroy cancer cells. To induce an immune response against cancer, activated dendritic cells (DCs) must present tumor antigens to T lymphocytes of patients. However, cancer patients' DCs are frequently defective, therefore, they are prone to induce rather tolerance than immune responses. In this context, loading tumor antigens into DCs and, at the same time, activating these cells, is a tempting goal within the field. Thus, we investigated the effects of cationic liposomes on the DCs differentiation/maturation, evaluating their surface phenotype and ability to stimulate T lymphocytes proliferation in vitro. The cationic liposomes composed by egg phosphatidylcholine, 1,2-dioleoyl-3-trimethylammonium propane and 1,2-dioleoylphosphatidylethanolamine (50/25/25% molar) were prepared by the thin film method followed by extrusion (65 nm, polydispersity of 0.13) and by the dehydration-rehydration method (95% of the population 107 nm, polydispersity of 0.52). The phenotypic analysis of dendritic cells and the analysis of T lymphocyte proliferation were performed by flow cytometry and showed that both cationic liposomes were incorporated and activated dendritic cells. Extruded liposomes were better incorporated and induced higher CD86 expression for dendritic cells than dehydrated-rehydrated vesicles. Furthermore, dendritic cells which internalized extruded liposomes also provided stronger T lymphocyte stimulation. Thus, cationic liposomes with a smaller size and polydispersity seem to be better incorporated by dendritic cells. Hence, these cationic liposomes could be used as a potential tool in further cancer immunotherapy strategies and contribute to new strategies in immunotherapy. PMID:27398454

  10. A Review on Composite Liposomal Technologies for Specialized Drug Delivery

    PubMed Central

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

    2011-01-01

    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. PMID:21490759

  11. Urinary microalbumin measurement using a homogeneous liposomal immunoassay.

    PubMed

    Frost, S J; Chakraborty, J; Firth, G B

    1996-08-14

    A homogeneous colorimetric immunoassay which has been developed for urinary microalbumin utilizes complement-mediated immunolysis of liposomes containing the dye, sulphorhodamine B. Unlike a previously described model complement-mediated liposomal assay for serum albumin (Frost et al., 1994) which was competitive, this assay uses a sandwich-type format and Fab' (antialbumin)-coated liposomes to increase the assay sensitivity. The liposomal assay, performed using a Cobas Bio analyser (Roche, Welwyn Garden City, UK), gave an acceptable correlation with a radioimmunoassay (NETRIA, London, UK): r = 0.94; y (liposomal assay) = 1.09 x (radioimmunoassay) - 1.54 mg/1. The imprecisions of the assays were similar and matrix effects due to the use of urine samples were determined to be acceptably small. The assay demonstrates the advantage of using Fab'-coated liposomes in sandwich-type liposomal immunoassays over liposomes coated with intact antibody, which failed to elicit complement-mediated immunolysis. PMID:8765163

  12. Amphiphilic vinyl polymers effectively prolong liposome circulation time in vivo.

    PubMed

    Torchilin, V P; Shtilman, M I; Trubetskoy, V S; Whiteman, K; Milstein, A M

    1994-10-12

    Newly synthesized amphiphilic polyacrylamide and poly(vinyl pyrrolidone), single terminus-modified with long-chain fatty acyl groups, are able to incorporate into the liposomal membrane, and similar to poly(ethylene glycol) prolong liposome circulation in vivo and decrease liposome accumulation in the liver. Protective efficacy of modified polymers increases with the increase in the length of acyl moiety and decreases for higher molecular weight polymers. The data on amphiphilic polymer-modified liposome biodistribution are presented.

  13. Photoluminescence of nitro-substituted europium (III) phthalocyanines

    SciTech Connect

    Ziminov, A. V. Polevaya, Yu. A.; Jourre, T. A.; Ramsh, S. M.; Mezdrogina, M. M.; Poletaev, N. K.

    2010-08-15

    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.

  14. Magnetic interaction in oxygenated alpha Fe-phthalocyanines

    SciTech Connect

    Kuzmann, Ernő Homonnay, Zoltán; Horváth, Attila; Pechousek, Jiri; Cuda, Jan; Machala, Libor; Zoppellaro, Giorgio; Zboril, Radek; Klencsár, Zoltán; Kubuki, Shiro; Nath, Amar

    2014-10-27

    Alpha iron phthalocyanines (α-FePc) oxygenated at low temperatures were investigated with the help of {sup 57}Fe Mössbauer spectroscopy, magnetization measurements (SQUID) and X-ray diffractometry (XRD). Mössbauer spectroscopy revealed that upon oxygenation of α-FePc, new species were formed which could be associated with Fe{sup III}Pc oxygen adducts. Unexpectedly, magnetically split spectrum of oxygenated α-FePc was observed below 20 K. In-field Mössbauer spectra in a 5 T external magnetic field at 5K and magnetization measurements indicate antiferromagnetic coupling in oxygenated α-FePc.

  15. Controlling the orbital sequence in individual Cu-phthalocyanine molecules.

    PubMed

    Uhlmann, C; Swart, I; Repp, J

    2013-02-13

    We report on the controlled change of the energetic ordering of molecular orbitals. Negatively charged copper(II)phthalocyanine on NaCl/Cu(100) undergoes a Jahn-Teller distortion that lifts the degeneracy of two frontier orbitals. The energetic order of the levels can be controlled by Au and Ag atoms in the vicinity of the molecule. As only one of the states is occupied, the control of the energetic order is accompanied by bistable changes of the charge distribution inside the molecule, rendering it a bistable switch.

  16. Photoconductivity study of acid on Zinc phthalocyanine pyridine thin films

    NASA Astrophysics Data System (ADS)

    Singh, Sukhwinder; Saini, G. S. S.; Tripathi, S. K.

    2016-05-01

    The Metal Phthalocyanine (MPc) have attracted much interest because of chemical and high thermal stability. Molecules forming a crystal of MPc are held together by weak attractive Vander Waals forces. Organic semiconductors have π conjugate bonds which allow electrons to move via π-electron cloud overlaps. Conduction mechanisms for organic semiconductor are mainly through tunneling; hopping between localized states, mobility gaps, and phonon assisted hopping. The photo conductivity of thin films of these complexes changes when exposed to oxidizing and reducing gases. Arrhenius plot is used to find the thermal activation energy in the intrinsic region and impurity scattering region. Arrhenius plotsare used to find the thermal activation energy.

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

    NASA Astrophysics Data System (ADS)

    Nishida, Krista Rachel Akiko

    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

  18. Liposome technology. Volume III: Targeted drug delivery and biological interaction

    SciTech Connect

    Gregoriadis, G.

    1984-01-01

    These three volumes cover liposome technology in pharmacology and medicine. Contributors emphasize methodology used in their own laboratories, and include a brief introduction, coverage of relevant literature, applications and critical evaluations for the methods they describe. In Volume III, the growing variety of techniques yielding targeted liposomes and approaches of studying liposomal behavior both in vitro and in vivo are discussed.

  19. Surface Engineering of Liposomes for Stealth Behavior

    PubMed Central

    Nag, Okhil K.; Awasthi, Vibhudutta

    2013-01-01

    Liposomes are used as a delivery vehicle for drug molecules and imaging agents. The major impetus in their biomedical applications comes from the ability to prolong their circulation half-life after administration. Conventional liposomes are easily recognized by the mononuclear phagocyte system and are rapidly cleared from the blood stream. Modification of the liposomal surface with hydrophilic polymers delays the elimination process by endowing them with stealth properties. In recent times, the development of various materials for surface engineering of liposomes and other nanomaterials has made remarkable progress. Poly(ethylene glycol)-linked phospholipids (PEG-PLs) are the best representatives of such materials. Although PEG-PLs have served the formulation scientists amazingly well, closer scrutiny has uncovered a few shortcomings, especially pertaining to immunogenicity and pharmaceutical characteristics (drug loading, targeting, etc.) of PEG. On the other hand, researchers have also begun questioning the biological behavior of the phospholipid portion in PEG-PLs. Consequently, stealth lipopolymers consisting of non-phospholipids and PEG-alternatives are being developed. These novel lipopolymers offer the potential advantages of structural versatility, reduced complement activation, greater stability, flexible handling and storage procedures and low cost. In this article, we review the materials available as alternatives to PEG and PEG-lipopolymers for effective surface modification of liposomes. PMID:24300562

  20. Magnetic nanoparticles for "smart liposomes".

    PubMed

    Nakayama, Yoshitaka; Mustapić, Mislav; Ebrahimian, Haleh; Wagner, Pawel; Kim, Jung Ho; Hossain, Md Shahriar Al; Horvat, Joseph; Martinac, Boris

    2015-12-01

    Liposomal drug delivery systems (LDDSs) are promising tools used for the treatment of diseases where highly toxic pharmacological agents are administered. Currently, destabilising LDDSs by a specific stimulus at a target site remains a major challenge. The bacterial mechanosensitive channel of large conductance (MscL) presents an excellent candidate biomolecule that could be employed as a remotely controlled pore-forming nanovalve for triggered drug release from LDDSs. In this study, we developed superparamagnetic nanoparticles for activation of the MscL nanovalves by magnetic field. Synthesised CoFe2O4 nanoparticles with the radius less than 10 nm were labelled by SH groups for attachment to MscL. Activation of MscL by magnetic field with the nanoparticles attached was examined by the patch clamp technique showing that the number of activated channels under ramp pressure increased upon application of the magnetic field. In addition, we have not observed any cytotoxicity of the nanoparticles in human cultured cells. Our study suggests the possibility of using magnetic nanoparticles as a specific trigger for activation of MscL nanovalves for drug release in LDDSs. PMID:26184724

  1. Liposome-Loaded Cell Backpacks.

    PubMed

    Polak, Roberta; Lim, Rosanna M; Beppu, Marisa M; Pitombo, Ronaldo N M; Cohen, Robert E; Rubner, Michael F

    2015-12-30

    Cell backpacks, or micron-scale patches of a few hundred nanometers in thickness fabricated by layer-by-layer (LbL) assembly, are potentially useful vehicles for targeted drug delivery on the cellular level. In this work, echogenic liposomes (ELIPs) containing the anticancer drug doxorubicin (DOX) are embedded into backpacks through electrostatic interactions and LbL assembly. Poly(allylamine hydrochloride)/poly(acrylic acid) (PAH/PAA)n , and poly(diallyldimethylammonium chloride)/poly(styrene sulfonate) (PDAC/SPS)n film systems show the greatest ELIP incorporation of the films studied while maintaining the structural integrity of the vesicles. The use of ELIPs for drug encapsulation into backpacks facilitates up to three times greater DOX loading compared to backpacks without ELIPs. Cytotoxicity studies reveal that monocyte backpack conjugates remain viable even after 72 h, demonstrating promise as drug delivery vehicles. Because artificial vesicles can load many different types of drugs, ELIP containing backpacks offer a unique versatility for broadening the range of possible applications for cell backpacks. PMID:26616471

  2. In vitro characteristics of liposomes and double liposomes prepared using a novel glass beads method.

    PubMed

    Yamabe, Kenji; Kato, Yoshinori; Onishi, Hiraku; Machida, Yoshiharu

    2003-06-01

    A novel preparative method for liposomes and double liposomes (DL) using glass beads was superior to a glass-filter method developed previously. Lipid dissolved in chloroform was poured into a kjeldahl flask with glass beads (BZ-04, 0.350-0.500 mm phi; BZ-3, 2.794-3.962 mm phi; or BZ-6, 5.613-6.680 mm phi), and the organic solvent was evaporated. The lipid layer that formed on the glass beads was hydrated with 1.5 ml of the suspension of inner liposomes at a temperature above the phase transition temperature of the lipids employed, and was agitated vigorously. Erythrosine (ER) was used as a model drug. The size of liposomes prepared by the glass beads method depended on the size of the glass beads. The size of the liposomes became smaller as glass beads with a smaller size were used. A high encapsulation efficiency was observed when glass bead blends consisting of two different sizes were used. Large sizes (BZ-3/BZ-6) had a tendency to show high encapsulation efficiency and size also played an important role in the formation of liposomes. DL formation inhibited the release of ER and DL formative efficiency was markedly improved by means of the glass beads method. These findings suggested that the glass beads method developed in this study conferred a high drug loading and a high DL formation on liposomes compared with ordinary methods.

  3. Spectroscopic insights on energy transfer phenomenon from phthalocyanine to gold nanoparticle and role of phthalocyanine-gold nanoparticle conjugate over supramolecular interaction between fullerene and phthalocyanine in solution

    NASA Astrophysics Data System (ADS)

    Ray, Anamika; Bhattacharya, Sumanta

    2016-05-01

    This letter envisages the photophysical insights on phthalocyanine (Pc)-gold nanoparticle (AuNp) conjugate in solution. Both steady state and time-resolved fluorescence studies evoke remarkable enhancement in energy transfer efficiency from ZnPc to AuNp in comparison to free-base Pc (H2Pc) in toluene. It is observed that in presence of AuNp, selectivity in binding for the non-covalent complex of H2Pc with PC70BM (a fullerene derivative) is found to be ∼3.0 times higher compared to ZnPc-PC70BM system. Dynamic light scattering, transmission electron microscope, atomic force microscope and fluorescence microscope measurements provide very good support in favour of the rationale behind Pc-AuNp interaction in solution.

  4. Unprecedented Phthalocyanines Bearing Eight Di-butylamino Peripheral Substituents: Synthesis, Spectroscopy, and Structure.

    PubMed

    Chen, Yuxiang; Cao, Wei; Wang, Kang; Jiang, Jianzhuang

    2015-10-19

    Unprecedented 2,3,9,10,16,17,23,24-octakis(di-butylamino)phthalocyanine compounds M{Pc[N(C4H9)2]8} (M = 2H, Mg, Cu, Zn) (1-4) were prepared and structurally characterized on the basis of single-crystal X-ray diffraction analysis, representing the first structurally characterized alkylamino-substituted phthalocyanine examples. These novel phthalocyanine derivatives have also been characterized by a wide range of spectroscopic methods including MALDI-TOF mass spectra, NMR, electronic absorption, and IR spectroscopy in addition to elemental analysis. Their electrochemistry was also studied by cyclic voltammetry.

  5. Titanium and Ruthenium Phthalocyanines for NO2 Sensors: A Mini-Review

    PubMed Central

    Paoletti, Anna Maria; Pennesi, Giovanna; Rossi, Gentilina; Generosi, Amanda; Paci, Barbara; Albertini, Valerio Rossi

    2009-01-01

    This review presents studies devoted to the description and comprehension of phenomena connected with the sensing behaviour towards NO2 of films of two phthalocyanines, titanium bis-phthalocyanine and ruthenium phthalocyanine. Spectroscopic, conductometric, and morphological features recorded during exposure to the gas are explained and the mechanisms of gas-molecule interaction are also elucidated. The review also shows how X-ray reflectivity can be a useful tool for monitoring morphological parameters such as thickness and roughness that are demonstrated to be sensitive variables for monitoring the exposure of thin films of sensor materials to NO2 gas. PMID:22346697

  6. Highly soluble 3,4-(dimethoxyphenylthio) substituted phthalocyanines: synthesis, photophysical and photochemical studies.

    PubMed

    Öztürk, Cansu; Erdoğmuş, Ali; Durmuş, Mahmut; Uğur, Ahmet Lütfi; Kılıçarslan, Fatma Aytan; Erden, Ibrahim

    2012-02-01

    The synthesis of a new 3,4-(dimethoxyphenylthio) substituted phthalonitrile (1) and its soluble metal free (2), zinc (II) (3), oxo-titanium (IV) (4) and nickel (II) (5) phthalocyanine derivatives are reported for the first time. The new compounds have been characterized by elemental analysis, FT-IR, (1)H NMR, UV-Vis, fluorescence spectroscopies and mass spectra. General trends are described for fluorescence, photodegradation and singlet oxygen quantum yields and fluorescence lifetimes of oxo-titanium (IV) and zinc (II) phthalocyanine compounds in dimethylsulfoxide (DMSO). The effects of the metal ion on the photophysical and photochemical parameters for these phthalocyanines (3 and 4) are also reported. PMID:22112573

  7. Dehydration resistance of liposomes containing trehalose glycolipids

    NASA Astrophysics Data System (ADS)

    Nyberg, Kendra; Goulding, Morgan; Parthasarathy, Raghuveer

    2010-03-01

    The pathogen, Mycobacterium tuberculosis, has an unusual outer membrane containing trehalose glycolipids that may contribute to its ability to survive freezing and dehydration. Based on our recent discovery that trehalose glycolipids confer dehydration resistance to supported lipid monolayers (Biophys. J. 94: 4718-4724 (2008); Langmuir 25: 5193-5198, (2009)), we hypothesized that liposomes containing synthetic trehalose glycolipids may be dehydration-resistant as well. To test this, we measured the leakage of encapsulated fluorophores and larger macromolecular cargo from such liposomes subject to freeze drying. Both leakage assays and size measurements show that the liposomes are dehydration-resistant. In addition to demonstrating a possibly technologically useful encapsulation platform, our results corroborate the view that encapsulation in a trehalose-glycolipid-rich membrane is a biophysically viable route to protection of mycobacteria from environmental stresses.

  8. Light-Activated Content Release from Liposomes

    PubMed Central

    Leung, Sarah J.; Romanowski, Marek

    2012-01-01

    Successful integration of diagnostic and therapeutic actions at the level of individual cells requires new materials that combine biological compatibility with functional versatility. This review focuses on the development of liposome-based functional materials, where payload release is activated by light. Methods of sensitizing liposomes to light have progressed from the use of organic molecular moieties to the use of metallic plasmon resonant structures. This development has facilitated application of near infrared light for activation, which is preferred for its deep penetration and low phototoxicity in biological tissues. Presented mechanisms of light-activated liposomal content release enable precise in vitro manipulation of minute amounts of reagents, but their use in clinical diagnostic and therapeutic applications will require demonstration of safety and efficacy. PMID:23139729

  9. Bioavailability of Polyphenol Liposomes: A Challenge Ahead

    PubMed Central

    Mignet, Nathalie; Seguin, Johanne; Chabot, Guy G.

    2013-01-01

    Dietary polyphenols, including flavonoids, have long been recognized as a source of important molecules involved in the prevention of several diseases, including cancer. However, because of their poor bioavailability, polyphenols remain difficult to be employed clinically. Over the past few years, a renewed interest has been devoted to the use of liposomes as carriers aimed at increasing the bioavailability and, hence, the therapeutic benefits of polyphenols. In this paper, we review the causes of the poor bioavailability of polyphenols and concentrate on their liposomal formulations, which offer a means of improving their pharmacokinetics and pharmacodynamics. The problems linked to their development and their potential therapeutic advantages are reviewed. Future directions for liposomal polyphenol development are suggested. PMID:24300518

  10. STX-liposome conjugates as candidate vaccines.

    PubMed

    Uchida, Tetsuya

    2003-09-01

    Infection with Shiga toxin-producing (Stx) Escherichia coli (STEC) currently represents a serious public health problem due to its life-threatening complications: hemorrhagic colitis and hemolytic uremic syndrome. An inability to induce neutralizing antibody in response to primary STEC infection has been reported in STEC-infected humans. Therefore, active immunization with detoxified Stx to induce the production of neutralizing antibodies against Stx is currently an attractive option. Although this would not prevent the spread of infection, it would protect against death caused by cytotoxin-producing E. coli infection. Stx coupled with liposomes effectively induced protection against challenge with lethal doses of Stx in mice and in monkeys. Unique characteristics of antigen-liposome conjugates found in our investigations are reviewed, and the possible application of Stx-liposome conjugates in vaccines for the prevention of life-threatening systemic complications caused by STEC infection is discussed.

  11. Compartmentalization of Gd liposomes: the quenching effect explained.

    PubMed

    Guenoun, Jamal; Doeswijk, Gabriela N; Krestin, Gabriel P; Bernsen, Monique R

    2016-01-01

    Cationic liposomes carrying high [Gd] can be used as efficient cell-labeling agents. In a compartmentalized state, Gd can cause signal loss (relaxivity quenching). The contributions of liposomal [Gd], size and compartmentalization state to relaxivity quenching were assessed. The dependency of signal intensity (SI) on intraliposomal [Gd] was assessed comparing three different [Gd] (0.3, 0.6 and 1.0 M Gd) in both small (80 nm) and large (120 nm) cationic liposomes. In addition, five compartmentalization states were compared: free Gd, intact Gd liposomes, ruptured Gd liposomes, Gd liposomes in intact cells and Gd liposomes in ruptured cells (simulating cell death). Gd also causes R2 effects, which is often overlooked. Therefore, both R1 and R2 relaxation rates of a dilution range were measured by T1 and T2 mapping on a 7 T clinical scanner. Less is more. As the unidirectional water efflux rate (outbound across the liposome membrane, κle) is proportional to the surface:volume ratio, smaller liposomes yielded a consistently higher R1 than larger liposomes. For equal voxel [Gd] less concentrated liposomes (0.3 M Gd) yielded higher R1/R2 ratio because of the higher extraliposomal water fraction (vl ). Gd exhibits a dualistic behavior: from hypointensity to hyperintensity to hypointensity, with decreasing [Gd]. Regarding compartmentalization, fewer membrane barriers means a higher R1 /R2 ratio. Gd liposomes exhibit a versatile contrast behavior, dependent on the compartmentalization state, liposomal size, intraliposomal [Gd] and liposome number. Both R1 and R2 effects contribute to this. The versatility allows one to tailor the optimal liposomal formulation to desired goals in cell labeling and tracking.

  12. Release Pattern of Liposomal Bupivacaine in Artificial Cerebrospinal Fluid

    PubMed Central

    Düzlü, Ayşe Ünal; Günaydın, Berrin; Şüküroğlu, Murat Kadir; Değim, İsmail Tuncer

    2016-01-01

    Objective We aimed to compare the possible controlled release profile of multilamellar liposomal bupivacaine formulations with non-liposomal forms in artificial cerebrospinal fluid (CSF) under in vitro conditions. Methods Liposome formulations were prepared using a dry-film hydration method. Then, an artificial CSF-buffered solution was prepared. Bupivacaine base with liposomal bupivacaine base, bupivacaine HCl with liposomal bupivacaine HCl and bupivacaine HCl were added in a Franz diffusion cell. These solutions were kept in a hot water bath for 24 h. The samples were taken at 0.5, 1, 3, 6, 12 and 24 h (1st series of experiment). Solutions of bupivacaine base with liposomal bupivacaine base and bupivacaine HCl with liposomal bupivacaine HCl were centrifuged to obtain liposomal bupivacaine base and liposomal bupivacaine HCl. Afterwards, liposomal bupivacaine base and liposomal bupivacaine HCl were added in a Franz diffusion cell. After keeping these solutions in a hot water bath for 24 h as well, the samples were taken at the same time intervals (2nd series of experiment). All samples (54 from the 1st experiment and 36 from the 2nd experiment) were analysed with high-performance liquid chromatography and ultra-performance liquid chromatography and their chromatograms were obtained. Results After obtaining calibration curves for bupivacaine base and HCl, release patterns of these formulations were plotted. A markedly controlled slow-release pattern was observed for multilamellar liposomal bupivacaine than for non-liposomal bupivacaine in artificial CSF. Conclusion Demonstration of controlled slow-release profile for mutilamellar liposomal bupivacaine in artificial CSF in vitro might support intrathecal use of liposomal bupivacaine in vivo in animal studies. PMID:27366547

  13. Spin Exchange Interaction in Substituted Copper Phthalocyanine Crystalline Thin Films.

    PubMed

    Rawat, Naveen; Pan, Zhenwen; Lamarche, Cody J; Wetherby, Anthony; Waterman, Rory; Tokumoto, Takahisa; Cherian, Judy G; Headrick, Randall L; McGill, Stephen A; Furis, Madalina I

    2015-11-12

    The origins of spin exchange in crystalline thin films of Copper Octabutoxy Phthalocyanine (Cu-OBPc) are investigated using Magnetic Circular Dichroism (MCD) spectroscopy. These studies are made possible by a solution deposition technique which produces highly ordered films with macroscopic grain sizes suitable for optical studies. For temperatures lower than 2 K, the contribution of a specific state in the valence band manifold originating from the hybridized lone pair in nitrogen orbitals of the Phthalocyanine ring, bears the Brillouin-like signature of an exchange interaction with the localized d-shell Cu spins. A comprehensive MCD spectral analysis coupled with a molecular field model of a σπ - d exchange analogous to sp-d interactions in Diluted Magnetic Semiconductors (DMS) renders an enhanced Zeeman splitting and a modified g-factor of -4 for the electrons that mediate the interaction. These studies define an experimental tool for identifying electronic states involved in spin-dependent exchange interactions in organic materials.

  14. Soluble copper phthalocyanine applied for organic solar cells.

    PubMed

    Zhang, Tianhui; Piao, Lingyu; Zha, Suling; Jiang, Chao; Xu, Zheng; Gao, Liyan; Wu, Qian; Kong, Chao

    2011-11-01

    A soluble derivative of copper phthalocyanine, that is 2,9,16,23-tetra carboxyl copper phthalocyanine (CuTCPc), is synthesized in this paper. The applications of CuTCPc as donor and interlayer materials in solar cell devices are investigated. The results demonstrate that when CuTCPc is used as a donor material, the performance of the device ITO/CuTCPc/PCBM/Al shows an open circuit voltage (V(OC)) of 0.54 V, a short circuit current (J(SC)) of 0.825 mA/cm2, a fill factor (FF) of 32.3% and the power conversion efficiency (nu) of 0.14%. When CuTCPc acts as an interlayer, the performance of the device ITO/CuTCPc/P3HT:PCBM/Al is improved: J(SC) increases to 3.12 mA/cm2, V(OC) increases to 0.59 V, FF increases to 33.8%, and the corresponding nu is 0.62%.

  15. Asymmetric Zinc Phthalocyanines as Dye-Sensitized Solar Cells

    NASA Astrophysics Data System (ADS)

    Tunc, Gulenay; Yavuz, Yunus; Gurek, Aysegul; Canimkurbey, Betul; Kosemen, Arif; San, Sait Eren; Ahsen, Vefa

    Dye-sensitized solar cells (DSSCs) have received increasing attention due to their high incident to photon efficiency, easy fabrication and low production cost . Tremendous research efforts have been devoted to the development of new and efficient sensitizers suitable for practical use. In TiO2-based DSSCs, efficiencies of up to 11.4% under simulated sunlight have been obtained with rutheniumepolypyridyl complexes. However, the main drawback of ruthenium complexes is the lack of absorption in the red region of the visible light and the high cost. For this reason, dyes with large and stable p-conjugated systems such as porphyrins and phthalocyanines are important classes of potential sensitizers for highly efficient DSSCs. Phthalocyanines (Pcs) have been widely used as sensitizers because of their improved light-harvesting properties in the far red- and near-IR spectral regions and their extraordinary robustness [1]. In this work, a series of asymmetric Zn(II) Pcs bearing a carboxylic acid group and six hexylthia groups either at the peripheral or non-peripheral positions have been designed and synthesized to investigate the influence of the COOH group and the positions of hexylthia groups on the dye-sensitized solar cell (DSSC) performance.

  16. Spin Exchange Interaction in Substituted Copper Phthalocyanine Crystalline Thin Films.

    PubMed

    Rawat, Naveen; Pan, Zhenwen; Lamarche, Cody J; Wetherby, Anthony; Waterman, Rory; Tokumoto, Takahisa; Cherian, Judy G; Headrick, Randall L; McGill, Stephen A; Furis, Madalina I

    2015-01-01

    The origins of spin exchange in crystalline thin films of Copper Octabutoxy Phthalocyanine (Cu-OBPc) are investigated using Magnetic Circular Dichroism (MCD) spectroscopy. These studies are made possible by a solution deposition technique which produces highly ordered films with macroscopic grain sizes suitable for optical studies. For temperatures lower than 2 K, the contribution of a specific state in the valence band manifold originating from the hybridized lone pair in nitrogen orbitals of the Phthalocyanine ring, bears the Brillouin-like signature of an exchange interaction with the localized d-shell Cu spins. A comprehensive MCD spectral analysis coupled with a molecular field model of a σπ - d exchange analogous to sp-d interactions in Diluted Magnetic Semiconductors (DMS) renders an enhanced Zeeman splitting and a modified g-factor of -4 for the electrons that mediate the interaction. These studies define an experimental tool for identifying electronic states involved in spin-dependent exchange interactions in organic materials. PMID:26559337

  17. Spin Exchange Interaction in Substituted Copper Phthalocyanine Crystalline Thin Films

    NASA Astrophysics Data System (ADS)

    Rawat, Naveen; Pan, Zhenwen; Lamarche, Cody J.; Wetherby, Anthony; Waterman, Rory; Tokumoto, Takahisa; Cherian, Judy G.; Headrick, Randall L.; McGill, Stephen A.; Furis, Madalina I.

    2015-11-01

    The origins of spin exchange in crystalline thin films of Copper Octabutoxy Phthalocyanine (Cu-OBPc) are investigated using Magnetic Circular Dichroism (MCD) spectroscopy. These studies are made possible by a solution deposition technique which produces highly ordered films with macroscopic grain sizes suitable for optical studies. For temperatures lower than 2 K, the contribution of a specific state in the valence band manifold originating from the hybridized lone pair in nitrogen orbitals of the Phthalocyanine ring, bears the Brillouin-like signature of an exchange interaction with the localized d-shell Cu spins. A comprehensive MCD spectral analysis coupled with a molecular field model of a σπ - d exchange analogous to sp-d interactions in Diluted Magnetic Semiconductors (DMS) renders an enhanced Zeeman splitting and a modified g-factor of -4 for the electrons that mediate the interaction. These studies define an experimental tool for identifying electronic states involved in spin-dependent exchange interactions in organic materials.

  18. Spin Exchange Interaction in Substituted Copper Phthalocyanine Crystalline Thin Films

    PubMed Central

    Rawat, Naveen; Pan, Zhenwen; Lamarche, Cody J.; Wetherby, Anthony; Waterman, Rory; Tokumoto, Takahisa; Cherian, Judy G.; Headrick, Randall L.; McGill, Stephen A.; Furis, Madalina I.

    2015-01-01

    The origins of spin exchange in crystalline thin films of Copper Octabutoxy Phthalocyanine (Cu-OBPc) are investigated using Magnetic Circular Dichroism (MCD) spectroscopy. These studies are made possible by a solution deposition technique which produces highly ordered films with macroscopic grain sizes suitable for optical studies. For temperatures lower than 2 K, the contribution of a specific state in the valence band manifold originating from the hybridized lone pair in nitrogen orbitals of the Phthalocyanine ring, bears the Brillouin-like signature of an exchange interaction with the localized d-shell Cu spins. A comprehensive MCD spectral analysis coupled with a molecular field model of a σπ − d exchange analogous to sp-d interactions in Diluted Magnetic Semiconductors (DMS) renders an enhanced Zeeman splitting and a modified g-factor of −4 for the electrons that mediate the interaction. These studies define an experimental tool for identifying electronic states involved in spin-dependent exchange interactions in organic materials. PMID:26559337

  19. Recent Trends of Polymer Mediated Liposomal Gene Delivery System

    PubMed Central

    Lee, Sang-Soo; George Priya Doss, C.; Yagihara, Shin; Kim, Do-Young

    2014-01-01

    Advancement in the gene delivery system have resulted in clinical successes in gene therapy for patients with several genetic diseases, such as immunodeficiency diseases, X-linked adrenoleukodystrophy (X-ALD) blindness, thalassemia, and many more. Among various delivery systems, liposomal mediated gene delivery route is offering great promises for gene therapy. This review is an attempt to depict a portrait about the polymer based liposomal gene delivery systems and their future applications. Herein, we have discussed in detail the characteristics of liposome, importance of polymer for liposome formulation, gene delivery, and future direction of liposome based gene delivery as a whole. PMID:25250340

  20. Microfluidic-Enabled Liposomes Elucidate Size-Dependent Transdermal Transport

    PubMed Central

    Junqueira, Mariana; Vreeland, Wyatt N.; Quezado, Zenaide; Finkel, Julia C.; DeVoe, Don L.

    2014-01-01

    Microfluidic synthesis of small and nearly-monodisperse liposomes is used to investigate the size-dependent passive transdermal transport of nanoscale lipid vesicles. While large liposomes with diameters above 105 nm are found to be excluded from deeper skin layers past the stratum corneum, the primary barrier to nanoparticle transport, liposomes with mean diameters between 31–41 nm exhibit significantly enhanced penetration. Furthermore, multicolor fluorescence imaging reveals that the smaller liposomes pass rapidly through the stratum corneum without vesicle rupture. These findings reveal that nanoscale liposomes with well-controlled size and minimal size variance are excellent vehicles for transdermal delivery of functional nanoparticle drugs. PMID:24658111

  1. Ligand-targeted liposome design: challenges and fundamental considerations.

    PubMed

    Noble, Gavin T; Stefanick, Jared F; Ashley, Jonathan D; Kiziltepe, Tanyel; Bilgicer, Basar

    2014-01-01

    Nanomedicine, particularly liposomal drug delivery, has expanded considerably over the past few decades, and several liposomal drugs are already providing improved clinical outcomes. Liposomes have now progressed beyond simple, inert drug carriers and can be designed to be highly responsive in vivo, with active targeting, increased stealth, and controlled drug-release properties. Ligand-targeted liposomes (LTLs) have the potential to revolutionize the treatment of cancer. However, these highly engineered liposomes generate new problems, such as accelerated clearance from circulation, compromised targeting owing to non-specific serum protein binding, and hindered tumor penetration. This article highlights recent challenges facing LTL strategies and describes the advanced design elements used to circumvent them.

  2. Preparation and characterization of hydroxyapatite/liposome core shell nanocomposites

    NASA Astrophysics Data System (ADS)

    Chu, Maoquan; Liu, Guojie

    2005-08-01

    Hydroxyapatite (HAP)/liposome core-shell nanocomposites have been prepared at room temperature. The liposome shells and the precipitate cores ranged in diameter mainly from 80 to 140 nm and from 40 to 120 nm, respectively. Rod-like whiskers ranging in length mainly from 10 to 30 nm were obtained after separating the precipitates from the liposomes. In contrast, the whiskers synthesized without liposomes ranged in length mainly from 70 to 140 nm. The precipitates synthesized both with and without liposomes were poorly crystalline, and had a similar chemical composition to the natural HAP.

  3. Application of fluorescence labeled liposome nanoparticles in the cell imaging

    NASA Astrophysics Data System (ADS)

    Hu, Jianbing; Li, Huimin; He, Xiaoxiao; Gong, Ping; Wang, Kemin; Zhang, Shouchun

    2007-05-01

    Fluorescence labeled liposome nanoparticles were prepared by dispersion of film method. The size of nanoparticles was around 50 nm. DPPE-FITC synthesized in our lab was used to label the liposome nanoparticles. Anti-cytokeratins 19 antibody was connected to the surface of the fluorescence liposome nanoparticles. After incubation with MGC cells and COS-7 cells for 30 min, MGC cells were selectively recognized by anti-cytokeratins 19 antibody modified liposome nanoparticles and well imaged under laser confocal microscope. This fluorescence labeled liposome nanoparticles is expected to have good applications in cell recognition and tumor diagnosis.

  4. Method of encapsulating polyaminopolycarboxylic acid chelating agents in liposomes

    DOEpatents

    Rahman, Yueh Erh

    1977-11-10

    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.

  5. Therapeutic gas delivery via microbubbles and liposomes.

    PubMed

    Fix, Samantha M; Borden, Mark A; Dayton, Paul A

    2015-07-10

    Gaseous molecules including nitric oxide, hydrogen sulfide, carbon monoxide and oxygen mediate numerous cell signaling pathways and have important physiological roles. Several noble gasses have been shown to elicit biological responses. These bioactive gasses hold great therapeutic potential, however, their controlled delivery remains a significant challenge. Recently, researchers have begun using microbubbles and liposomes to encapsulate such gasses for parenteral delivery. The resultant particles are acoustically active, and ultrasound can be used to stimulate and/or image gas release in a targeted region. This review provides a summary of recent advances in therapeutic gas delivery using microbubbles and liposomes.

  6. Overcoming cellular and tissue barriers to improve liposomal drug delivery

    NASA Astrophysics Data System (ADS)

    Kohli, Aditya G.

    Forty years of liposome research have demonstrated that the anti-tumor efficacy of liposomal therapies is, in part, driven by three parameters: 1) liposome formulation and lipid biophysics, 2) accumulation and distribution in the tumor, and 3) release of the payload at the site of interest. This thesis outlines three studies that improve on each of these delivery steps. In the first study, we engineer a novel class of zwitterlipids with an inverted headgroup architecture that have remarkable biophysical properties and may be useful for drug delivery applications. After intravenous administration, liposomes accumulate in the tumor by the enhanced permeability and retention effect. However, the tumor stroma often limits liposome efficacy by preventing distribution into the tumor. In the second study, we demonstrate that depletion of hyaluronan in the tumor stroma improves the distribution and efficacy of DoxilRTM in murine 4T1 tumors. Once a liposome has distributed to the therapeutic site, it must release its payload over the correct timescale. Few facile methods exist to quantify the release of liposome therapeutics in vivo. In the third study, we outline and validate a simple, robust, and quantitative method for tracking the rate and extent of release of liposome contents in vivo. This tool should facilitate a better understanding of the pharmacodynamics of liposome-encapsulated drugs in animals. This work highlights aspects of liposome behavior that have prevented successful clinical translation and proposes alternative approaches to improve liposome drug delivery.

  7. Sensing response of copper phthalocyanine salt dispersed glass with organic vapours

    NASA Astrophysics Data System (ADS)

    Ridhi, R.; Sachdeva, Sheenam; Saini, G. S. S.; Tripathi, S. K.

    2016-05-01

    Copper Phthalocyanine and other Metal Phthalocyanines are very flexible and tuned easily to modify their structural, spectroscopic, optical and electrical properties by either functionalizing them with various substituent groups or by replacing or adding a ligand to the central metal atom in the phthalocyanine ring and accordingly can be made sensitive and selective to various organic species or gaseous vapours. In the present work, we have dispersed Copper Phthalocyanine Salt (CuPcS) in sol-gel glass form using chemical route sol-gel method and studied its sensing mechanism with organic vapours like methanol and benzene and found that current increases onto their exposure with vapours. A variation in the activation energies was also observed with exposure of vapours.

  8. Copper phthalocyanine films deposited by liquid-liquid interface recrystallization technique (LLIRCT).

    PubMed

    Patil, K R; Sathaye, S D; Hawaldar, R; Sathe, B R; Mandale, A B; Mitra, A

    2007-11-15

    The simple recrystallization process is innovatively used to obtain the nanoparticles of copper phthalocyanine by a simple method. Liquid-liquid interface recrystallization technique (LLIRCT) has been employed successfully to produce small sized copper phthalocyanine nanoparticles with diameter between 3-5 nm. The TEM-SAED studies revealed the formation of 3-5 nm sized with beta-phase dominated mixture of alpha and beta copper phthalocyanine nanoparticles. The XRD, SEM, and the UV-vis studies were further carried out to confirm the formation of copper phthalocyanine thin films. The cyclic voltametry (CV) studies conclude that redox reaction is totally reversible one electron transfer process. The process is attributed to Cu(II)/Cu(I) redox reaction.

  9. Phthalocyanines: a new class of G-quadruplex-ligands with many potential applications.

    PubMed

    Yaku, Hidenobu; Fujimoto, Takeshi; Murashima, Takashi; Miyoshi, Daisuke; Sugimoto, Naoki

    2012-06-25

    A G-quadruplex is a four-stranded DNA structure featuring stacked guanine tetrads, G-quartets. Formation of a G-quadruplex in telomere DNA can inhibit telomerase activity; therefore, development of G-quadruplex-ligands, which induce and/or stabilize G-quadruplexes, has become an area of great interest. Phthalocyanine derivatives have substantial potential as high-affinity G-quadruplex-ligands because these planar chromophores are similar in size and shape to the G-quartets. Here, we focus on the latest findings on phthalocyanine derivatives as G-quadruplex-ligands, and discuss the mechanisms by which phthalocyanines bind to G-quadruplexes with high affinity and selectivity. We also discuss potential biomedical and organic electronic applications of phthalocyanines that are dependent on their photophysical properties.

  10. Photochemical and Photophysical Properties of Phthalocyanines Modified with Optically Active Alcohols.

    PubMed

    Ramos, Aline A; Nascimento, Francisco B; de Souza, Thaiza F M; Omori, Alvaro T; Manieri, Tânia M; Cerchiaro, Giselle; Ribeiro, Anderson O

    2015-07-24

    Three phthalocyanine derivatives were synthesized and characterized: one modified with a racemic mixture of 1-(4-bromophenyl)ethanol and two other macrocycles modified with each one of the enantioenriched isomers (R)-1-(4-bromophenyl)ethanol and (S)-1-(4-bromophenyl)ethanol. The compounds were characterized by 1H-NMR spectroscopy, mass spectrometry, UV-Vis absorption, and excitation and emission spectra. Additionally, partition coefficient values and the quantum yield of the generation of oxygen reactive species were determined. Interestingly, the phthalocyanine containing a (R)-1-(4-bromophenyl)ethoxy moiety showed higher quantum yield of reactive oxygen species generation than other compounds under the same conditions. In addition, the obtained fluorescence microscopy and cell viability results have shown that these phthalocyanines have different interactions with mammary MCF-7 cells. Therefore, our results indicate that the photochemical and biological properties of phthalocyanines with chiral ligands should be evaluated separately for each enantiomeric species.

  11. Heteroleptic naphthalo-phthalocyaninates of lutetium: synthesis and spectral and conductivity properties.

    PubMed

    Dubinina, Tatiana V; Kosov, Anton D; Petrusevich, Elizaveta F; Maklakov, Sergey S; Borisova, Nataliya E; Tomilova, Larisa G; Zefirov, Nikolay S

    2015-05-01

    Novel heteroleptic naphthalo-phthalocyaninates of lutetium possessing a symmetrical substituted naphthalocyanine deck were synthesized on the basis of two preformed synthetic blocks: naphthalocyanine ligand and lutetium phthalocyaninates. The compounds obtained were characterized by (1)H NMR and high-resolution MALDI-TOF/TOF mass spectrometry. The correlation between the nature of the substituents and the spectral properties of the target complexes was determined by the introduction of electron-donating (aryl-, aryloxy-) or electron-withdrawing (chloro-) substituents into the phthalocyanine deck. In addition, the nature of peripheral substituents was shown not to affect drastically the phthalocyanine conductivity and activation energy. Conductivity properties depend on thin film morphology which, in turn, relies on intermolecular π-π interactions.

  12. Phthalocyanines: a new class of G-quadruplex-ligands with many potential applications.

    PubMed

    Yaku, Hidenobu; Fujimoto, Takeshi; Murashima, Takashi; Miyoshi, Daisuke; Sugimoto, Naoki

    2012-06-25

    A G-quadruplex is a four-stranded DNA structure featuring stacked guanine tetrads, G-quartets. Formation of a G-quadruplex in telomere DNA can inhibit telomerase activity; therefore, development of G-quadruplex-ligands, which induce and/or stabilize G-quadruplexes, has become an area of great interest. Phthalocyanine derivatives have substantial potential as high-affinity G-quadruplex-ligands because these planar chromophores are similar in size and shape to the G-quartets. Here, we focus on the latest findings on phthalocyanine derivatives as G-quadruplex-ligands, and discuss the mechanisms by which phthalocyanines bind to G-quadruplexes with high affinity and selectivity. We also discuss potential biomedical and organic electronic applications of phthalocyanines that are dependent on their photophysical properties. PMID:22590705

  13. Characterisation of gene delivery using liposomal bubbles and ultrasound

    NASA Astrophysics Data System (ADS)

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

    2011-09-01

    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.

  14. Aerosolized liposomes with dipalmitoyl phosphatidylcholine enhance pulmonary insulin delivery.

    PubMed

    Chono, Sumio; Fukuchi, Rie; Seki, Toshinobu; Morimoto, Kazuhiro

    2009-07-20

    The pulmonary insulin delivery characteristics of liposomes were examined. Aerosolized liposomes containing insulin were administered into rat lungs and the enhancing effect on insulin delivery was evaluated by changes of plasma glucose levels. Liposomes with dipalmitoyl phosphatidylcholine (DPPC) enhanced pulmonary insulin delivery in rats, however, liposomes with dilauroyl, dimyristoyl, distearoyl or dioleoyl phosphatidylcholine did not. Liposomes with DPPC also enhanced the in vitro permeation of FITC dextran (Mw 4400, FD-4) through the calu-3 cell monolayer by reducing the transepithelial electrical resistance and did not harm lung tissues in rats. These findings suggest that liposomes with DPPC enhance pulmonary insulin delivery by opening the epithelial cell space in the pulmonary mucosa not mucosal cell damage. Liposomes with DPPC could be useful as a pulmonary delivery system for peptide and protein drugs.

  15. Liposomes of terbutaline sulphate: in vitro and in vivo studies.

    PubMed

    Joshi, M R; Misra, A N

    1999-09-01

    In vitro studies were conducted to understand the comparative drug diffusion pattern, across artificial membrane, of the drug and of the prepared liposomes of different liposomal membrane composition. In vivo studies were carried out to determine the extent and time-course of pulmonary tissue uptake of administered liposomes containing terbutaline sulphate(TER) on rat lungs. In vitro studies revealed that the drug released from the prepared liposomes obeys Higuchi's diffusion controlled model. Different loading doses and release patterns of drug from the liposomes can be obtained by altering the PC:CHOL ratio and incorporation of cholesterol was found to reduce permeability of the membrane. Similarly drug absorption in vivo in rat's lung following intratracheal instillation, prolonged over 12 hr by liposomal entrapment of TER. The findings of present investigation indicated that liposomally encapsulated TER can be used for pulmonary delivery for maximizing the therapeutic efficacy and reducing undesirable side effects. PMID:10687283

  16. Fully protected glycosylated zinc (II) phthalocyanine shows high uptake and photodynamic cytotoxicity in MCF-7 cancer cells.

    PubMed

    Kimani, Stanley G; Shmigol, Tatiana A; Hammond, Samantha; Phillips, James B; Bruce, James I; MacRobert, Alexander J; Malakhov, Mikhail V; Golding, Jon P

    2013-01-01

    Phthalocyanine photosensitizers are effective in anticancer photodynamic therapy (PDT) but suffer from limited solubility, limited cellular uptake and limited selectivity for cancer cells. To improve these characteristics, we synthesized isopropylidene-protected and partially deprotected tetra β-glycosylated zinc (II) phthalocyanines and compared their uptake and accumulation kinetics, subcellular localization, in vitro photocytotoxicity and reactive oxygen species generation with those of disulfonated aluminum phthalocyanine. In MCF-7 cancer cells, one of the compounds, zinc phthalocyanine {4}, demonstrated 10-fold higher uptake, 5-fold greater PDT-induced cellular reactive oxygen species concentration and 2-fold greater phototoxicity than equimolar (9 μm) disulfonated aluminum phthalocyanine. Thus, isopropylidene-protected β-glycosylation of phthalocyanines provides a simple method of improving the efficacy of PDT.

  17. Potential Effect of Liposomes and Liposome-Encapsulated Botulinum Toxin and Tacrolimus in the Treatment of Bladder Dysfunction.

    PubMed

    Janicki, Joseph J; Chancellor, Michael B; Kaufman, Jonathan; Gruber, Michele A; Chancellor, David D

    2016-03-18

    Bladder drug delivery via catheter instillation is a widely used treatment for recurrence of superficial bladder cancer. Intravesical instillation of liposomal botulinum toxin has recently shown promise in the treatment of overactive bladder and interstitial cystitis/bladder pain syndrome, and studies of liposomal tacrolimus instillations show promise in the treatment of hemorrhagic cystitis. Liposomes are lipid vesicles composed of phospholipid bilayers surrounding an aqueous core that can encapsulate hydrophilic and hydrophobic drug molecules to be delivered to cells via endocytosis. This review will present new developments on instillations of liposomes and liposome-encapsulated drugs into the urinary bladder for treating lower urinary tract dysfunction.

  18. Potential Effect of Liposomes and Liposome-Encapsulated Botulinum Toxin and Tacrolimus in the Treatment of Bladder Dysfunction

    PubMed Central

    Janicki, Joseph J.; Chancellor, Michael B.; Kaufman, Jonathan; Gruber, Michele A.; Chancellor, David D.

    2016-01-01

    Bladder drug delivery via catheter instillation is a widely used treatment for recurrence of superficial bladder cancer. Intravesical instillation of liposomal botulinum toxin has recently shown promise in the treatment of overactive bladder and interstitial cystitis/bladder pain syndrome, and studies of liposomal tacrolimus instillations show promise in the treatment of hemorrhagic cystitis. Liposomes are lipid vesicles composed of phospholipid bilayers surrounding an aqueous core that can encapsulate hydrophilic and hydrophobic drug molecules to be delivered to cells via endocytosis. This review will present new developments on instillations of liposomes and liposome-encapsulated drugs into the urinary bladder for treating lower urinary tract dysfunction. PMID:26999210

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

    PubMed

    Arsić, Ivana; Tadić, Vanja; Vlaović, Djordje; Homšek, Irena; Vesić, Sonja; Isailović, Gorana; Vuleta, Gordana

    2011-02-01

    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.

  20. Modeling the interactions of phthalocyanines in water: from the Cu(II)-tetrasulphonate to the metal-free phthalocyanine.

    PubMed

    Martín, Elisa I; Martínez, Jose M; Sánchez Marcos, Enrique

    2011-01-14

    A quantum and statistical study on the effects of the ions Cu(2+) and SO(3)(-) in the solvent structure around the metal-free phthalocyanine (H(2)Pc) is presented. We developed an ab initio interaction potential for the system CuPc-H(2)O based on quantum chemical calculations and studied its transferability to the H(2)Pc-H(2)O and [CuPc(SO(3))(4)](4-)-H(2)O interactions. The use of the molecular dynamics technique allows the determination of energetic and structural properties of CuPc, H(2)Pc, and [CuPc(SO(3))(4)](4-) in water and the understanding of the keys for the different behaviors of the three phthalocyanine (Pc) derivatives in water. The inclusion of the Cu(2+) cation in the Pc structure reinforces the appearance of two axial water molecules and second-shell water molecules in the solvent structure, whereas the presence of SO(3)(-) anions implies a well defined hydration shell of about eight water molecules around them making the macrocycle soluble in water. Debye-Waller factors for axial water molecules have been obtained in order to examine the potential sensitivity of the extended x-ray absorption fine structure technique to detect the axial water molecules.

  1. Modeling the interactions of phthalocyanines in water: From the Cu(II)-tetrasulphonate to the metal-free phthalocyanine

    NASA Astrophysics Data System (ADS)

    Martín, Elisa I.; Martínez, Jose M.; Marcos, Enrique Sánchez

    2011-01-01

    A quantum and statistical study on the effects of the ions Cu^{2+} and SO3- in the solvent structure around the metal-free phthalocyanine (H2Pc) is presented. We developed an ab initio interaction potential for the system CuPc-H2O based on quantum chemical calculations and studied its transferability to the H2Pc-H2O and [CuPc(SO3)4]^{4-}-H2O interactions. The use of the molecular dynamics technique allows the determination of energetic and structural properties of CuPc, H2Pc, and [CuPc(SO3)4]^{4-} in water and the understanding of the keys for the different behaviors of the three phthalocyanine (Pc) derivatives in water. The inclusion of the Cu^{2+} cation in the Pc structure reinforces the appearance of two axial water molecules and second-shell water molecules in the solvent structure, whereas the presence of SO3{}^- anions implies a well defined hydration shell of about eight water molecules around them making the macrocycle soluble in water. Debye-Waller factors for axial water molecules have been obtained in order to examine the potential sensitivity of the extended x-ray absorption fine structure technique to detect the axial water molecules.

  2. Theoretical investigation of the electronic structure of a substituted nickel phthalocyanine

    NASA Astrophysics Data System (ADS)

    Kaur, Prabhjot; Sachdeva, Ritika; Singh, Sukhwinder

    2016-05-01

    The optimized geometry and electronic structure of an organic compound nickel phthalocyanine tetrasulfonic acid tetra sodium salt have been investigated using density functional theory. We have also optimized the structure of nickel phthalocyanine tetrasulfonic acid tetra sodium salt in dimethyl sulfoxide to study effects of solvent on the electronic structure and transitions. Experimentally, the electronic transitions have been studied using UV-VIS spectroscopic technique. It is observed that the electronic transitions obtained from the theoretical studies generally agree with the experiment.

  3. Communication: Influence of graphene interlayers on the interaction between cobalt phthalocyanine and Ni(111)

    SciTech Connect

    Uihlein, Johannes; Peisert, Heiko; Glaser, Mathias; Polek, Malgorzata; Adler, Hilmar; Petraki, Fotini; Chasse, Thomas; Ovsyannikov, Ruslan; Bauer, Maximilian

    2013-02-28

    The influence of graphene interlayers on electronic interface properties of cobalt phthalocyanine on Ni(111) is studied using both photoemission and X-ray absorption spectroscopy. A charge transfer associated with a redistribution of the d-electrons at the Co-atom of the phthalocyanine occurs at the interface to Ni(111). Even a graphene buffer layer cannot prevent the charge transfer at the interface to Ni(111); however, the detailed electronic situation is different.

  4. DFT study of the effect of substitution on the molecular structure of copper phthalocyanine

    NASA Astrophysics Data System (ADS)

    Kaur, Prabhjot; Sachdeva, Ritika; Singh, Sukhwinder; Saini, G. S. S.

    2016-05-01

    To study the effect of sulfonic acid group as substituent on the molecular structure of an organic compound copper Phthalocyanine, the optimized geometry, mulliken charges, energies and dipole momemts of copper phthalocyanine and copper phthalocyaninetetrasulfonic acid tetra sodium salt have been investigated using density functional theory. Also to predict the change in reactive sites after substitution, molecular electrostatic potential maps for both the molecules have been calculated.

  5. Aldehyde Substituted Phthalocyanines: Synthesis, Characterization and Investigation of Photophysical and Photochemical Properties.

    PubMed

    Sen, Pinar; Yildiz, S Zeki; Erdoğmuş, Ali; Dege, Necmi; Atalay, Yusuf

    2016-07-01

    The new free and nickel phthalocyanine derivatives, tetrakis [(2-formylphenoxy)-phthalocyanine (4), tetrakis [(2-formylphenoxy)-phthalocyaninato]nickel(II) (5) have been synthesized via de-protection of tetra acetal-substituted phthalocyanines in acetic acid/FeCl3 system. The starting phthalocyanines, tetrakis [(2-(1,3-dioxolan-2-yl)phenoxy)-phthalocyanine (2) and tetrakis [(2-(1,3-dioxolan-2-yl)phenoxy)-phthalocyaninato]nickel (3), were prepared by the tetramerization of 4-(2-(1,3-dioxolan-2-yl) phenoxy) phthalonitrile (1). The new compounds have been characterized by the combination of FT-IR, (1)H NMR, UV-Vis, Mass spectra and elemental analysis. Compound 1 crystallizes in the Orthorhombic, space group Pbca with a = 9.2542 (4) Å, b = 13.3299 (5) Å, c = 23.2333 (11) Å, and Z = 8. Compound 1 is built up from two planar groups (phthalonitrile and phenoxy), with a dihedral angle of 69.693(36)° between them and non-planar dioxolane group. We report a combined experimental and theoretical study on molecule 1, as well. Geometric, spectroscopic and electronic properties of compound 1 has been calculated using B3LYP method and 6-311++G(dp) basis set. Fluorescence spectroscopy was applied to record the photoluminescence spectra of the prepared phthalocyanines and the photophysical and photochemical properties were examined in DMSO. PMID:27294562

  6. Assembly of Multi-Phthalocyanines on a Porphyrin Template by Fourfold Rotaxane Formation.

    PubMed

    Yamada, Yasuyuki; Kato, Tatsuhisa; Tanaka, Kentaro

    2016-08-22

    A stacked assembly composed of a porphyrin and two phthalocyanines was prepared through fourfold rotaxane formation. Two phthalocyanine molecules, bearing four 24-crown-8 units, were assembled onto a porphyrin template incorporating four sidechains with two dialkylammonium ions each through pseudorotaxane formation between crown ether units and ammonium ions. The Staudinger phosphite reaction, as the stoppering reaction, resulted in the formation of the stacked heterotrimer composed of a porphyrin and two phthalocyanines connected through a fourfold rotaxane structure. UV/Vis spectroscopic and electrochemical studies of the heterotrimer indicated that there is a significant electronic interaction between the two phthalocyanine units due to the close stacking. The electrochemical oxidation process of the stacked heterotrimer was studied by cyclic voltammetry and spectroelectrochemistry. Electron paramagnetic resonance (EPR) spectroscopy of a dinuclear Cu(II) complex, in which two Cu(II) phthalocyanines were assembled on a metal-free porphyrin template, revealed that two Cu(II) phthalocyanines were located within the stacking distance, which resulted in an antiferromagnetic interaction between the two S=1/2 spins in the ground state of the Cu(2+) ions in the heterotrimer. PMID:27417388

  7. Evaluation of antibacterial properties of novel phthalocyanines against Escherichia coli--comparison of analytical methods.

    PubMed

    Mikula, Premysl; Kalhotka, Libor; Jancula, Daniel; Zezulka, Stepan; Korinkova, Radka; Cerny, Jiri; Marsalek, Blahoslav; Toman, Petr

    2014-09-01

    We analyzed antibacterial effects of several novel phthalocyanines against Escherichia coli and evaluated the suitability of flow cytometry for the detection of antibacterial effects of phthalocyanines in comparison with routinely used cultivation. After 3h of exposure under cool white light eight cationic phthalocyanines showed very high antibacterial activity in the concentration of 2.00 mg L(-1) and four of them were even efficient in the concentration of 0.20 mg L(-1). Antibacterial activity of neutral and anionic compounds was considerably lower or even negligible. No antibacterial effect was detected when bacteria were exposed without illumination. Binding affinity to bacterial cells was found to represent an important parameter influencing phthalocyanine antibacterial activity that can be modified by total charge of peripheral substituents and by the presence of suitable functional groups inside them. Agglomeration of cells observed in suspensions treated with a higher concentration of certain cationic phthalocyanines (the strongest binders to bacterial membrane) affected cytometric measurements of total cell counts, thus without appropriate pretreatment of the sample before analysis this parameter seems not to be fully valid in the evaluation of phthalocyanine antibacterial activity. Cytometric measurement of cell membrane integrity appears to be a suitable and even more sensitive parameter than cultivation.

  8. The quest for biocompatible phthalocyanines for molecular imaging: Photophysics, relaxometry and cytotoxicity studies.

    PubMed

    Pinto, Sara M A; Tomé, Vanessa A; Calvete, Mário J F; Pereira, Mariette M; Burrows, Hugh D; Cardoso, Ana M S; Pallier, Agnès; C A Castro, M Margarida; Tóth, Éva; Geraldes, Carlos F G C

    2016-01-01

    Water soluble phthalocyanines bearing either four PEG500 or four choline substituents in the macrocyclic structure, as well as their Zn(II) and Mn(III) complexes were synthesized. The metal-free and Zn(II) complexes present relatively high fluorescence quantum yields (up to 0.30), while the Mn(III) complexes show no fluorescence as a consequence of rapid non-radiative deactivation of the Mn(III) phthalocyanine excited states through low-lying metal based or charge-transfer states. The effect of DMSO on the aggregation of the phthalocyanines was studied. It was not possible to obtain the Mn(II) complexes by reduction of the corresponding Mn(III) complexes due to the presence of electron donating substituents at the periphery of the phthalocyanines. The (1)H NMRD plots of the PEG500 and choline substituted Mn(III)-phthalocyanine complexes are typical of self-aggregated Mn(III) systems with r1 relaxivities of 4.0 and 5.7mM(-1)s(-1) at 20MHz and 25°C. The Mn(III)-phthalocyanine-PEG4 complex shows no significant cytotoxicity to HeLa cell cultures after 2h of incubation up to 2mM concentration. After 24h of cell exposure to the compound, significant toxicity was observed for all the concentrations tested with IC50 of 1.105mM.

  9. Studies of anti-fibrillogenic activity of phthalocyanines of zirconium containing out-of-plane ligands.

    PubMed

    Kovalska, Vladyslava; Losytskyy, Mykhaylo; Chernii, Viktor; Volkova, Kateryna; Tretyakova, Iryna; Cherepanov, Vsevolod; Yarmoluk, Sergiy; Volkov, Sergiy

    2012-01-01

    Series of phthalocyanines of zirconium containing lysine, citric, nonanoic acid residues and dibenzolylmethane groups as out-of-plane ligands are firstly studied as inhibitors of fibrillogenesis using cyanine-based fluorescent inhibitory assay. It was shown that studied phthalocyanines at concentration of 20μM inhibited aggregation reaction on 38.5-57.6% and inhibitory activity of phthalocyanines depended on the chemical nature of out-of-plane ligand. For the most active compound PcZrLys(2) (zirconium phthalocyanine containing lysine fragment) the efficient inhibitor concentration was estimated to be 37μM. AFM studies have shown that in the presence of PcZrLys(2) the inhibition of fibrils formation and formation of spherical oligomeric aggregates took place. Due to the ability of phthalocyanines to decrease efficiently protein aggregation into the amyloid fibrils, modification of phthalocyanine molecules via out-of-plane substitutions was proposed as approach for design of anti-fibrillogenic agents with required properties.

  10. Aldehyde Substituted Phthalocyanines: Synthesis, Characterization and Investigation of Photophysical and Photochemical Properties.

    PubMed

    Sen, Pinar; Yildiz, S Zeki; Erdoğmuş, Ali; Dege, Necmi; Atalay, Yusuf

    2016-07-01

    The new free and nickel phthalocyanine derivatives, tetrakis [(2-formylphenoxy)-phthalocyanine (4), tetrakis [(2-formylphenoxy)-phthalocyaninato]nickel(II) (5) have been synthesized via de-protection of tetra acetal-substituted phthalocyanines in acetic acid/FeCl3 system. The starting phthalocyanines, tetrakis [(2-(1,3-dioxolan-2-yl)phenoxy)-phthalocyanine (2) and tetrakis [(2-(1,3-dioxolan-2-yl)phenoxy)-phthalocyaninato]nickel (3), were prepared by the tetramerization of 4-(2-(1,3-dioxolan-2-yl) phenoxy) phthalonitrile (1). The new compounds have been characterized by the combination of FT-IR, (1)H NMR, UV-Vis, Mass spectra and elemental analysis. Compound 1 crystallizes in the Orthorhombic, space group Pbca with a = 9.2542 (4) Å, b = 13.3299 (5) Å, c = 23.2333 (11) Å, and Z = 8. Compound 1 is built up from two planar groups (phthalonitrile and phenoxy), with a dihedral angle of 69.693(36)° between them and non-planar dioxolane group. We report a combined experimental and theoretical study on molecule 1, as well. Geometric, spectroscopic and electronic properties of compound 1 has been calculated using B3LYP method and 6-311++G(dp) basis set. Fluorescence spectroscopy was applied to record the photoluminescence spectra of the prepared phthalocyanines and the photophysical and photochemical properties were examined in DMSO.

  11. Assembly of Multi-Phthalocyanines on a Porphyrin Template by Fourfold Rotaxane Formation.

    PubMed

    Yamada, Yasuyuki; Kato, Tatsuhisa; Tanaka, Kentaro

    2016-08-22

    A stacked assembly composed of a porphyrin and two phthalocyanines was prepared through fourfold rotaxane formation. Two phthalocyanine molecules, bearing four 24-crown-8 units, were assembled onto a porphyrin template incorporating four sidechains with two dialkylammonium ions each through pseudorotaxane formation between crown ether units and ammonium ions. The Staudinger phosphite reaction, as the stoppering reaction, resulted in the formation of the stacked heterotrimer composed of a porphyrin and two phthalocyanines connected through a fourfold rotaxane structure. UV/Vis spectroscopic and electrochemical studies of the heterotrimer indicated that there is a significant electronic interaction between the two phthalocyanine units due to the close stacking. The electrochemical oxidation process of the stacked heterotrimer was studied by cyclic voltammetry and spectroelectrochemistry. Electron paramagnetic resonance (EPR) spectroscopy of a dinuclear Cu(II) complex, in which two Cu(II) phthalocyanines were assembled on a metal-free porphyrin template, revealed that two Cu(II) phthalocyanines were located within the stacking distance, which resulted in an antiferromagnetic interaction between the two S=1/2 spins in the ground state of the Cu(2+) ions in the heterotrimer.

  12. Anti-fibrillogenic properties of phthalocyanines: effect of the out-of-plane ligands.

    PubMed

    Kovalska, V; Cherepanov, V; Losytskyy, M; Chernii, S; Senenko, A; Chernii, V; Tretyakova, I; Yarmoluk, S; Volkov, S

    2014-12-15

    The axially-coordinated phthalocyanines were previously reported as agents possessing strong anti-fibrillogenic properties. In the presented study we used the atomic force microscopy to investigate the intermediates and the products of insulin aggregation reaction formed in the presence of Zr and Hf phthalocyanine complexes that contain out-of-plane ligands of different size and nature. It is shown that while phthalocyanine-free insulin generated mostly amyloid fibrils with a diameter of 2-8nm and a length of up to 5μm, the presence of phthalocyanines with spatial bulky ligands (PcZrDbm2) leads to the redirection of the fibrillization reaction to the formation of the spherical oligomer aggregates with a diameter of 4-12nm. At the same time the phthalocyanine complex PcHfCl2 having the small-volume ligands induces the formation of large size insulin aggregates with a height of about 100nm that are supposed to be amorphous species. The study of the aggregation intermediates showed the certain similarity of the reaction passing for phthalocyanine-free insulin and insulin in the presence of PcZrDbm2. The large-size amorphous species were observed at the beginning of reaction, later they dissociated, leading to the formation and growth of the smaller size particles. The amyloid-sensitive cyanine dye 7519 demonstrates the strong fluorescent response both in the presence of fibrils and spherical oligomers, while it is non-sensitive to amorphous aggregates.

  13. Photodynamic therapy of melanoma using new, synthetic porphyrins and phthalocyanines as photosensitisers – a comparative study

    PubMed Central

    BALDEA, IOANA; ION, RODICA-MARIANA; OLTEANU, DIANA ELENA; NENU, IULIANA; TUDOR, DIANA; FILIP, ADRIANA GABRIELA

    2015-01-01

    Melanoma, a cancer that arises from melanocytes, is one of the most unresponsive cancers to known therapies and has a tendency to produce early metastases. Several studies showed encouraging results of the efficacy of photodynamic therapy (PDT) in melanoma, in different experimental settings in vitro and in vivo, as well as several clinical reports. Aims Our study focuses on testing the antimelanoma efficacy of several new, synthetic photosensitisers (PS), from two different chemical classes, respectively four porphyrins and six phthalocyanines. Methods These PS were tested in terms of cell toxicity and phototoxicity against a radial growth phase melanoma cell line (WM35), in vitro. Cells were exposed to different concentrations of the PS for 24h, washed, then irradiatied with red light (630 nm) 75 mJ/cm2 for the porphyrins and 1 J/cm2 for the phthalocyanines. Viability was measured using the MTS method. Results Two of the synthetic porphyrins, TTP and THNP, were active photosensitizers against WM35 melanoma in vitro. Phthalocyanines were effective in producing a dose dependent PDT-induced decrease in viability in a dose-dependent manner. The most efficient was Indium (III) Phthalocyanine chloride, a metal substituted phthalocyanine. Conclusions The most efficient photosensitizers for PDT in melanoma cells were the phthalocyanines in terms of tumor cell photokilling and decreased dark toxicity. PMID:26528068

  14. Properties of liposomal membranes containing lysolecithin.

    PubMed

    Kitagawa, T; Inoue, K; Nojima, S

    1976-06-01

    Liposomes have been prepared with lysolecithin (1-acyl-sn-3-glycerylphosphorylcholine), egg lecithin (3-sn-phosphatidylcholine), dicetyl phosphate, and cholesterol. The ability to function as a barrier to the diffusion of glucose marker and the sensitivities of the liposomes to hypotonic treatment and other reagents which modified the permeability were examined. Generally, lysolecithin incorporation decreased the effectiveness of the membranes as a barrier to glucose and made the membranes more "osmotically fragile." Cholesterol incorporation counteracted the effect of incorporated lysolecithin. The more cholesterol incorporated into liposomes, the more lysolecthin could be incorporated into the membrane without loss of function as a barrier. With more than 50 mole% of colesterol, lysolecithin alone could form membranes which were practically impermeable to glucose. The hemolytic activity of lysolecithin was affected by mixing with various lecithins or cholesterol. Liposomes containing lysolecithin, which have the ability to trap glucose marker, showed poor hemolytic activity, while lipid micelles with lysolecithin (which could trap little glucose) showed almost the same hemolytic activity as lysolecithin itself. There seems to be a close correlation between hemolytic activity and barrier function of lipid micelles. PMID:986392

  15. Fusion of Liposomes with Mitochondrial Inner Membranes

    NASA Astrophysics Data System (ADS)

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

    1980-01-01

    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.

  16. Properties of liposomal membranes containing lysolecithin.

    PubMed

    Kitagawa, T; Inoue, K; Nojima, S

    1976-06-01

    Liposomes have been prepared with lysolecithin (1-acyl-sn-3-glycerylphosphorylcholine), egg lecithin (3-sn-phosphatidylcholine), dicetyl phosphate, and cholesterol. The ability to function as a barrier to the diffusion of glucose marker and the sensitivities of the liposomes to hypotonic treatment and other reagents which modified the permeability were examined. Generally, lysolecithin incorporation decreased the effectiveness of the membranes as a barrier to glucose and made the membranes more "osmotically fragile." Cholesterol incorporation counteracted the effect of incorporated lysolecithin. The more cholesterol incorporated into liposomes, the more lysolecthin could be incorporated into the membrane without loss of function as a barrier. With more than 50 mole% of colesterol, lysolecithin alone could form membranes which were practically impermeable to glucose. The hemolytic activity of lysolecithin was affected by mixing with various lecithins or cholesterol. Liposomes containing lysolecithin, which have the ability to trap glucose marker, showed poor hemolytic activity, while lipid micelles with lysolecithin (which could trap little glucose) showed almost the same hemolytic activity as lysolecithin itself. There seems to be a close correlation between hemolytic activity and barrier function of lipid micelles.

  17. Bone marrow-targeted liposomal carriers

    PubMed Central

    Sou, Keitaro; Goins, Beth; Oyajobi, Babatunde O.; Travi, Bruno L.; Phillips, William T.

    2011-01-01

    Introduction Bone marrow targeted drug delivery systems appear to offer a promising strategy for advancing diagnostic, protective, and/or therapeutic medicine for the hematopoietic system. Liposome technology can provide a drug delivery system with high bone marrow targeting that is mediated by specific phagocytosis in bone marrow. Area covered This review focuses on a bone marrow specific liposome formulation labeled with technetium-99m (99mTc). Interspecies differences in bone marrow distribution of the bone marrow targeted formulation are emphasized. This review provides a liposome technology to target bone marrow. In addition, the selection of proper species for the investigation of bone marrow targeting is suggested. Expert opinion It can be speculated that the bone marrow macrophages have a role in the delivery of lipids to the bone marrow as a source of energy and for membrane biosynthesis or in the delivery of fat soluble vitamins for hematopoiesis. This homeostatic system offers a potent pathway to deliver drugs selectively into bone marrow tissues from blood. High selectivity of the present BMT-liposome formulation for bone marrow suggests the presence of an active and specific mechanism, but specific factors affecting the uptake of the bone marrow MPS are still unknown. Further investigation of this mechanism will increase our understanding of factors required for effective transport of agents to the bone marrow, and may provide an efficient system for bone marrow delivery for therapeutic purposes. PMID:21275831

  18. Influence of the Encapsulation Efficiency and Size of Liposome on the Oral Bioavailability of Griseofulvin-Loaded Liposomes

    PubMed Central

    Ong, Sandy Gim Ming; Ming, Long Chiau; Lee, Kah Seng; Yuen, Kah Hay

    2016-01-01

    The objective of the present study was to investigate the influence of the encapsulation efficiency and size of liposome on the oral bioavailability of griseofulvin-loaded liposomes. Griseofulvin-loaded liposomes with desired characteristics were prepared from pro-liposome using various techniques. To study the effect of encapsulation efficiency, three preparations of griseofulvin, namely, griseofulvin aqueous suspension and two griseofulvin-loaded liposomes with different amounts of griseofulvin encapsulated [i.e., F1 (32%) and F2(98%)], were administered to rats. On the other hand, to study the effect of liposome size, the rats were given three different griseofulvin-loaded liposomes of various sizes, generated via different mechanical dispersion techniques [i.e., FTS (142 nm), MS (357 nm) and NS (813 nm)], but with essentially similar encapsulation efficiencies (about 93%). Results indicated that the extent of bioavailability of griseofulvin was improved 1.7–2.0 times when given in the form of liposomes (F1) compared to griseofulvin suspension. Besides that, there was an approximately two-fold enhancement of the extent of bioavailability following administration of griseofulvin-loaded liposomes with higher encapsulation efficiency (F2), compared to those of F1. Also, the results showed that the extent of bioavailability of liposomal formulations with smaller sizes were higher by approximately three times compared to liposomal formulation of a larger size. Nevertheless, a further size reduction of griseofulvin-loaded liposome (≤400 nm) did not promote the uptake or bioavailability of griseofulvin. In conclusion, high drug encapsulation efficiency and small liposome size could enhance the oral bioavailability of griseofulvin-loaded liposomes and therefore these two parameters deserve careful consideration during formulation. PMID:27571096

  19. Influence of the Encapsulation Efficiency and Size of Liposome on the Oral Bioavailability of Griseofulvin-Loaded Liposomes.

    PubMed

    Ong, Sandy Gim Ming; Ming, Long Chiau; Lee, Kah Seng; Yuen, Kah Hay

    2016-01-01

    The objective of the present study was to investigate the influence of the encapsulation efficiency and size of liposome on the oral bioavailability of griseofulvin-loaded liposomes. Griseofulvin-loaded liposomes with desired characteristics were prepared from pro-liposome using various techniques. To study the effect of encapsulation efficiency, three preparations of griseofulvin, namely, griseofulvin aqueous suspension and two griseofulvin-loaded liposomes with different amounts of griseofulvin encapsulated [i.e., F1 (32%) and F2(98%)], were administered to rats. On the other hand, to study the effect of liposome size, the rats were given three different griseofulvin-loaded liposomes of various sizes, generated via different mechanical dispersion techniques [i.e., FTS (142 nm), MS (357 nm) and NS (813 nm)], but with essentially similar encapsulation efficiencies (about 93%). Results indicated that the extent of bioavailability of griseofulvin was improved 1.7-2.0 times when given in the form of liposomes (F1) compared to griseofulvin suspension. Besides that, there was an approximately two-fold enhancement of the extent of bioavailability following administration of griseofulvin-loaded liposomes with higher encapsulation efficiency (F2), compared to those of F1. Also, the results showed that the extent of bioavailability of liposomal formulations with smaller sizes were higher by approximately three times compared to liposomal formulation of a larger size. Nevertheless, a further size reduction of griseofulvin-loaded liposome (≤400 nm) did not promote the uptake or bioavailability of griseofulvin. In conclusion, high drug encapsulation efficiency and small liposome size could enhance the oral bioavailability of griseofulvin-loaded liposomes and therefore these two parameters deserve careful consideration during formulation. PMID:27571096

  20. Nanocomposite liposomes containing quantum dots and anticancer drugs for bioimaging and therapeutic delivery: a comparison of cationic, PEGylated and deformable liposomes

    NASA Astrophysics Data System (ADS)

    Wen, Chih-Jen; Sung, Calvin T.; Aljuffali, Ibrahim A.; Huang, Yu-Jie; Fang, Jia-You

    2013-08-01

    Multifunctional liposomes loaded with quantum dots (QDs) and anticancer drugs were prepared for simultaneous bioimaging and drug delivery. Different formulations, including cationic, PEGylated and deformable liposomes, were compared for their theranostic efficiency. We had evaluated the physicochemical characteristics of these liposomes. The developed liposomes were examined using experimental platforms of cytotoxicity, cell migration, cellular uptake, in vivo melanoma imaging and drug accumulation in tumors. The average size of various nanocomposite liposomes was found to be 92-134 nm. Transmission electron microscopy confirmed the presence of QDs within liposomal bilayers. The incorporation of polyethylene glycol (PEG) and Span 20 into the liposomes greatly increased the fluidity of the bilayers. The liposomes provided sustained release of camptothecin and irinotecan. The cytotoxicity and cell migration assay demonstrated superior activity of cationic liposomes compared with other carriers. Cationic liposomes also showed a significant fluorescence signal in melanoma cells after internalization. The liposomes were intratumorally administered to a melanoma-bearing mouse. Cationic liposomes showed the brightest fluorescence in tumors, followed by classical liposomes. This signal could last for up to 24 h for cationic nanosystems. Intratumoral accumulation of camptothecin from free control was 35 nmol g-1 it could be increased to 50 nmol g-1 after loading with cationic liposomes. However, encapsulation of irinotecan into liposomes did not further increase intratumoral drug accumulation. Cationic liposomes were preferable to other liposomes as nanocarriers in both bioimaging and therapeutic approaches.

  1. Photodynamic therapy potential of thiol-stabilized CdTe quantum dot-group 3A phthalocyanine conjugates (QD-Pc).

    PubMed

    Tekdaş, Duygu Aydın; Durmuş, Mahmut; Yanık, Hülya; Ahsen, Vefa

    2012-07-01

    Thiol stabilized CdTe quantum dot (QD) nanoparticles were synthesized in aqueous phase and were used as energy donors to tetra-triethyleneoxythia substituted aluminum, gallium and indium phthalocyanines through fluorescence resonance energy transfer (FRET). Energy transfer occurred from the QDs to phthalocyanines upon photoexcitation of the QDs. An enhancement in efficiency of energy transfer with the nature of the carboxylic thiol stabilizer on the QDs was observed. As a result of the nanoparticle and the phthalocyanine mixing, the photoluminescence efficiency of the phthalocyanine moieties in the mixtures does not strictly follow the quantum yields of the bare phthalocyanines. The photochemistry study of phthalocyanines in the presence of the QDs revealed high singlet oxygen quantum yield, hence the possibility of using QDs in combination with phthalocyanines as photosensitizers in photodynamic therapy of cancer. The fluorescence of the CdTe quantum dots-phthalocyanine conjugates (QDs-Pc) were effectively quenched by addition of 1,4-benzoquinone.

  2. Liposomal Encapsulated Rhodomyrtone: A Novel Antiacne Drug

    PubMed Central

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

    2013-01-01

    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 μmol/mL were used. Formulation with 60 μmol/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 ζ-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 μg/mL, respectively, while those of rhodomyrtone were 0.25–1 and 0.5–2 μg/mL, respectively. The MIC and MBC values of liposome formulation were more effective than topical drugs against Staphylococcus aureus and Staphylococcus epidermidis. PMID:23762104

  3. Liposome disposition in vivo. VI: Delivery to the lung

    SciTech Connect

    Abra, R.M.; Hunt, C.A.; Lau, D.T.

    1984-02-01

    The effect of negatively charged liposome components and vesicle size on the time course and dose dependency of liposome disposition in mice was studied with a view to optimizing liposome delivery to the lung. The disposition of large multilamellar liposomes was followed using 125I-labeled p-hydroxybenzamidine phosphatidyl ethanolamine. Of the three negatively charged liposome compositions studied (phosphatidyl choline-X-cholesterol-alpha-tocopherol, molar ratio: 4:1:5:0.1; X . phosphatidyl serine, dipalmitoyl phosphatidic acid, or phosphatidyl glycerol), phosphatidyl serine liposomes resulted in the greatest accumulation in lungs. Lung levels decreased up to 95 h postdose, at which time 6% of the liposome dose present at 2 h still remained. The disposition of phosphatidyl serine-containing liposomes was independent of dose for the range 0.04-21 mumol/animal. When liposomes containing phosphatidyl choline were prepared using a variety of extrusion and dialysis conditions, a strong link between liposome size and lung accumulation was revealed. A maximum lung accumulation of 30.9% of the administered dose was achieved with no detectable gross pathological lung lesions up to 24 h postdose.

  4. Covalent immobilization of liposomes on plasma functionalized metallic surfaces.

    PubMed

    Mourtas, S; Kastellorizios, M; Klepetsanis, P; Farsari, E; Amanatides, E; Mataras, D; Pistillo, B R; Favia, P; Sardella, E; d'Agostino, R; Antimisiaris, S G

    2011-05-01

    A method was developed to functionalize biomedical metals with liposomes. The novelty of the method includes the plasma-functionalization of the metal surface with proper chemical groups to be used as anchor sites for the covalent immobilization of the liposomes. Stainless steel (SS-316) disks were processed in radiofrequency glow discharges fed with vapors of acrylic acid to coat them with thin adherent films characterized by surface carboxylic groups, where liposomes were covalently bound through the formation of amide bonds. For this, liposomes decorated with polyethylene glycol molecules bearing terminal amine-groups were prepared. After ensuring that the liposomes remain intact, under the conditions applying for immobilization; different attachment conditions were evaluated (incubation time, concentration of liposome dispersion) for optimization of the technique. Immobilization of calcein-entrapping liposomes was evaluated by monitoring the percent of calcein attached on the surfaces. Best results were obtained when liposome dispersions with 5mg/ml (liposomal lipid) concentration were incubated on each disk for 24h at 37°C. The method is proposed for developing drug-eluting biomedical materials or devices by using liposomes that have appropriate membrane compositions and are loaded with drugs or other bioactive agents. PMID:21273051

  5. Bladder Uptake of Liposomes after Intravesical Administration Occurs by Endocytosis

    PubMed Central

    Rajaganapathy, Bharathi Raja; Chancellor, Michael B.; Nirmal, Jayabalan; Dang, Loan; Tyagi, Pradeep

    2015-01-01

    Liposomes have been used therapeutically and as a local drug delivery system in the bladder. However, the exact mechanism for the uptake of liposomes by bladder cells is unclear. In the present study, we investigated the role of endocytosis in the uptake of liposomes by cultured human UROtsa cells of urothelium and rat bladder. UROtsa cells were incubated in serum-free media with liposomes containing colloidal gold particles for 2 h either at 37°C or at 4°C. Transmission Electron Microscopy (TEM) images of cells incubated at 37°C found endocytic vesicles containing gold inside the cells. In contrast, only extracellular binding was noticed in cells incubated with liposomes at 4°C. Absence of liposome internalization at 4°C indicates the need of energy dependent endocytosis as the primary mechanism of entry of liposomes into the urothelium. Flow cytometry analysis revealed that the uptake of liposomes at 37°C occurs via clathrin mediated endocytosis. Based on these observations, we propose that clathrin mediated endocytosis is the main route of entry for liposomes into the urothelial layer of the bladder and the findings here support the usefulness of liposomes in intravesical drug delivery. PMID:25811468

  6. Charge dependent photodynamic activity of alanine based zinc phthalocyanines.

    PubMed

    Wang, Ao; Li, Yejing; Zhou, Lin; Yuan, Linxin; Lu, Shan; Lin, Yun; Zhou, Jiahong; Wei, Shaohua

    2014-12-01

    In this paper, to minimize the effects of different structure, three alanine-based zinc phthalocyanines (Pcs) of differing charges were engineered and synthesized with the same basic structure. On this premise, the relationship between nature of charge and photodynamic activity was studied. Besides, further verification and explanation of some inconsistent results were also carried out. The results showed that charge can influence the aggregation state, singlet oxygen generation ability and cellular uptake of Pcs, thereby affecting their photodynamic activity. In addition, the biomolecules inside cells may interact with Pcs of differing charges, which can also influence the aggregation state and singlet oxygen generation of the Pcs, and then influence the relationship between nature of charge and photodynamic activity.

  7. Correlation dependences in infrared spectra of metal phthalocyanines

    SciTech Connect

    Ziminov, A. V. Ramsh, S. M.; Terukov, E. I.; Trapeznikova, I. N.; Shamanin, V. V.; Yurre, T. A.

    2006-10-15

    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.

  8. Order on disorder: Copper phthalocyanine thin films on technical substrates

    SciTech Connect

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

    2001-07-01

    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.

  9. Giant ferromagnetic π -d interaction in a phthalocyanine molecule

    NASA Astrophysics Data System (ADS)

    Murakawa, H.; Kanda, A.; Ikeda, M.; Matsuda, M.; Hanasaki, N.

    2015-08-01

    We experimentally demonstrate that the ferromagnetic intramolecular π -d interaction works between an itinerant π -electron spin and a localized d -electron's magnetic moment in the iron-phthalocyanine (Pc) molecular compound. The evaluation of the hidden π -d coupling is achieved by preparing the isolated Fe(Pc )(CN ) 2 molecular solution with unpaired π - and d -electron spins, which is generated through the oxidization by iodine bromide (IBr). The monotonic increase of the magnetization with IBr addition and the saturation value of the Curie constant indicate the ferromagnetic π -d coupling. Furthermore, through the magnetization measurements of the single crystals of neutral π radical Fe(Pc )(CN ) 2.2 CHCl3 , we reveal that the on-site π -d interaction in Fe(Pc )(CN ) 2 is extremely large (Jπ d/kB>500 K ) among those in other molecular materials.

  10. Nonlinear Optothermal Properties of Metal-Free Phthalocyanine

    NASA Technical Reports Server (NTRS)

    Abdeldayem, Hossin A.; Frazier, Donald O.; Penn, Benjamin G.; Smith, David D.; Banks, Curtis E.

    1998-01-01

    The nonlinear optical properties of metal-free phthalocyanine (MFPC) thin films were examined using the second harmonic at 532 nm from a pulsed Nd:YAG laser, and the cw He-Ne , and Ar+ lasers. The He-Ne laser transmission at fixed input intensity was found to increase temporally within a time scale of twelve hours. The origin of this temporal change of transmission is discussed. The third order nonlinear susceptibilities (chi (exp(3))) by four-wave mixing were measured for films of different thickness. The saturation intensity of MFPC, and its absorption cross section, at 633 nm from a He-Ne laser, are reported. An optical bistability was recorded using a He-Ne laser. An AND logic gate was also demonstrated in the system. These phenomena in the system are attributed to refractive index modulation by thermal excitations.

  11. Percutaneous permeation measurement of topical phthalocyanine by photoacoustic technique

    NASA Astrophysics Data System (ADS)

    Silva, Emanoel P. O.; Barja, Paulo R.; Cardoso, Luiz E.; Beltrame, Milton

    2012-11-01

    This investigation have studied photoacoustic (PA) technique to percutaneous permeation of topical hydroxy-(29H,31H-phthalocyaninate) aluminum (PcAlOH) on pig ear skin. The PcAlOH was incorporated in an emulsion (O/W) (1 mg/dl) with assessed stability parameters of: pH, short and long term stability tests (in the several conditions). The skin was prepared through a heat separation technique, and with a scalpel, the outer skin of the cartilage was removed. The skins were then cut into 4 cm2 pieces and treated with sodium bromide 2 mol/L for 6 h at 37 °C. The epidermis layer was washed with purified water, dried, and stored under reduced pressure until use. The skin permeation kinetics was determined by photoacoustic technique in an open photoacoustic cell. Short (after preparation) and long-term stability tests showed no phase separation. The emulsion developed pH 7.6 and after incorporating the pH was unchanged. The typical times for percutaneous permeation of the emulsion base and emulsion + PcAlOH were 182 (±6) and 438 (±3) s, respectively. This study indicated that the formulations containing PcAlOH have stabile characteristics and show promising results in absorption into the skin. The presence of the photosensitive agent in the formulation contributed significantly to the greater absorption time than observed in the base formulation. The used photoacoustic technical to examine the penetration kinetics of PcAlOH in pig ear skin was adequate and may be employed in the determination of the percutaneous permeation of phthalocyanines.

  12. Tetra-triethyleneoxysulfonyl substituted zinc phthalocyanine for photodynamic cancer therapy.

    PubMed

    Kuzyniak, Weronika; Ermilov, Eugeny A; Atilla, Devrim; Gürek, Ayşe Gül; Nitzsche, Bianca; Derkow, Katja; Hoffmann, Björn; Steinemann, Gustav; Ahsen, Vefa; Höpfner, Michael

    2016-03-01

    Photodynamic therapy (PDT) has emerged as an effective and minimally invasive treatment option for several diseases, including some forms of cancer. However, several drawbacks of the approved photosensitizers (PS), such as insufficient light absorption at therapeutically relevant wavelengths hampered the clinical effectiveness of PDT. Phthalocyanines (Pc) are interesting PS-candidates with a strong light absorption in the favourable red spectral region and a high quantum yield of cancer cell destroying singlet oxygen generation. Here, we evaluated the suitability of tetra-triethyleneoxysulfonyl substituted zinc phthalocyanine (ZnPc) as novel PS for PDT. ZnPc-induced phototoxicity, induction of apoptosis as well as cell cycle arresting effects was studied in the human gastrointestinal cancer cell lines of different origin. Photoactivation of ZnPc-pretreated (1-10 μM) cancer cells was achieved by illumination with a broad band white light source (400-700 nm) at a power density of 10 J/cm(2). Photoactivation of ZnPc-loaded cells revealed strong phototoxic effects, leading to a dose-dependent decrease of cancer cell proliferation of up to almost 100%, the induction of apoptosis and a G1-phase arrest of the cell cycle, which was associated with decrease in cyclin D1 expression. By contrast, ZnPc-treatment without illumination did not induce any cytotoxicity, apoptosis, cell cycle arrest or decreased cell growth. Antiangiogenic effects of ZnPc-PDT were investigated in vivo by performing CAM assays, which revealed a marked degradation of blood vessels and the capillary plexus of the chorioallantoic membrane of fertilized chicken eggs. Based on our data we think that ZnPc may be a promising novel photosensitizer for innovative PDT.

  13. Electronic structure at transition metal phthalocyanine-transition metal oxide interfaces: Cobalt phthalocyanine on epitaxial MnO films

    SciTech Connect

    Glaser, Mathias; Peisert, Heiko Adler, Hilmar; Aygül, Umut; Ivanovic, Milutin; Chassé, Thomas; Nagel, Peter; Merz, Michael; Schuppler, Stefan

    2015-03-14

    The electronic structure of the interface between cobalt phthalocyanine (CoPc) and epitaxially grown manganese oxide (MnO) thin films is studied by means of photoemission (PES) and X-ray absorption spectroscopy (XAS). Our results reveal a flat-lying adsorption geometry of the molecules on the oxide surface which allows a maximal interaction between the π-system and the substrate. A charge transfer from MnO, in particular, to the central metal atom of CoPc is observed by both PES and XAS. The change of the shape of N-K XAS spectra at the interface points, however, to the involvement of the Pc macrocycle in the charge transfer process. As a consequence of the charge transfer, energetic shifts of MnO related core levels were observed, which are discussed in terms of a Fermi level shift in the semiconducting MnO films due to interface charge redistribution.

  14. Liposome-based drug delivery in breast cancer treatment

    PubMed Central

    Park, John W

    2002-01-01

    Drug delivery systems can in principle provide enhanced efficacy and/or reduced toxicity for anticancer agents. Long circulating macromolecular carriers such as liposomes can exploit the 'enhanced permeability and retention' effect for preferential extravasation from tumor vessels. Liposomal anthracyclines have achieved highly efficient drug encapsulation, resulting in significant anticancer activity with reduced cardiotoxicity, and include versions with greatly prolonged circulation such as liposomal daunorubicin and pegylated liposomal doxorubicin. Pegylated liposomal doxorubucin has shown substantial efficacy in breast cancer treatment both as monotherapy and in combination with other chemotherapeutics. Additional liposome constructs are being developed for the delivery of other drugs. The next generation of delivery systems will include true molecular targeting; immunoliposomes and other ligand-directed constructs represent an integration of biological components capable of tumor recognition with delivery technologies. PMID:12052251

  15. Advances and Challenges of Liposome Assisted Drug Delivery

    PubMed Central

    Sercombe, Lisa; Veerati, Tejaswi; Moheimani, Fatemeh; Wu, Sherry Y.; Sood, Anil K.; Hua, Susan

    2015-01-01

    The application of liposomes to assist drug delivery has already had a major impact on many biomedical areas. They have been shown to be beneficial for stabilizing therapeutic compounds, overcoming obstacles to cellular and tissue uptake, and improving biodistribution of compounds to target sites in vivo. This enables effective delivery of encapsulated compounds to target sites while minimizing systemic toxicity. Liposomes present as an attractive delivery system due to their flexible physicochemical and biophysical properties, which allow easy manipulation to address different delivery considerations. Despite considerable research in the last 50 years and the plethora of positive results in preclinical studies, the clinical translation of liposome assisted drug delivery platforms has progressed incrementally. In this review, we will discuss the advances in liposome assisted drug delivery, biological challenges that still remain, and current clinical and experimental use of liposomes for biomedical applications. The translational obstacles of liposomal technology will also be presented. PMID:26648870

  16. Investigating the Stability of eLiposomes at Elevated Temperatures.

    PubMed

    Husseini, Ghaleb A; Pitt, William G; Javadi, Marjan

    2015-08-01

    eLiposomes encapsulate a perfluorocarbon nanoemulsion droplet inside a liposome. Ultrasound is then used as a trigger mechanism to vaporize the perfluorocarbon, break the liposome, and release the desired drug to the tumor tissue. The purpose of this research is to show that eLiposomes synthesized using perfluoropentane are stable above the normal boiling point of the perfluoropentane and at body temperature and thus has potential for use in vivo. Experiments involving the release of fluorescent calcein molecules were performed on eLiposomes to measure the release of calcein at various temperatures in the absence of ultrasound. Results showed that eLiposomes are stable at body temperatures and that as the temperature increases above 40°C, calcein release from these novel nanocarriers increases.

  17. Recent advances in liposome surface modification for oral drug delivery.

    PubMed

    Nguyen, Thanh Xuan; Huang, Lin; Gauthier, Mario; Yang, Guang; Wang, Qun

    2016-05-01

    Oral delivery via the gastrointestinal (GI) tract is the dominant route for drug administration. Orally delivered liposomal carriers can enhance drug solubility and protect the encapsulated theraputic agents from the extreme conditions found in the GI tract. Liposomes, with their fluid lipid bilayer membrane and their nanoscale size, can significantly improve oral absorption. Unfortunately, the clinical applications of conventional liposomes have been hindered due to their poor stability and availability under the harsh conditions typically presented in the GI tract. To overcome this problem, the surface modification of liposomes has been investigated. Although liposome surface modification has been extensively studied for oral drug delivery, no review exists so far that adequately covers this topic. The purpose of this paper is to summarize and critically analyze emerging trends in liposome surface modification for oral drug delivery. PMID:27074098

  18. Liposome clusters with shear stress-induced membrane permeability.

    PubMed

    Yoshimoto, Makoto; Tamura, Ryota; Natsume, Tomotaka

    2013-09-01

    Clusters of negatively charged liposomes were prepared by the addition of Ca(2+) and characterized in their structure and membrane permeability under shear stress. The liposomes mainly used were composed of zwitterionic 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), 20 mol% negatively charged 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol (POPG) and 30 mol% cholesterol. The liposomes with mean diameter of 193 nm were aggregated into the clusters with a distribution peak at about 1.5 μm in the 50mM Tris buffer solution of pH 8.5 at the lipid and Ca(2+) concentrations of 1.0mM and 40 mM, respectively. More than 90% of liposomes were redispersed at the Ca(2+) concentration of 80 mM. POPG-rich liposomes (POPC/POPG/cholesterol=5:65:30 [lipid]=1.0mM) were irreversibly aggregated at [Ca(2+)]≥ 10 mM, indicating the significant contribution of POPC to the reversible clustering of liposomes. The membranes of liposome clusters were impermeable to 5(6)-carboxyfluorescein (CF) in the static liquid system at 25°C due to the decrease in specific surface area of the liposomal system. In the shear flow, in clear contrast, continuous membrane permeation of CF was observed at the shear rate of 1.5 × 10(3)s(-1), exhibiting comparable membrane permeability to the non-clustered liposomes. The theoretical analysis of modified DLVO potential indicated that liposome membranes were not in contact with each other within the clusters. Therefore, the liposome clusters are structurally flexible under the applied shear stress, providing sufficient lipid membrane-water interfacial area for the permeation of CF. The results obtained would be important to control the formation of liposome clusters and their permeabilization for biochemical and biomedical applications.

  19. Liposomes as nanoreactors for the photochemical synthesis of gold nanoparticles.

    PubMed

    Gudlur, Sushanth; Sandén, Camilla; Matoušková, Petra; Fasciani, Chiara; Aili, Daniel

    2015-10-15

    A simple and novel method for the photochemical synthesis of AuNPs in liposomes is described. Gold salt is co-encapsulated with the photoinitiator Irgacure-2959 in POPC liposomes prepared via traditional thin-film hydration technique. UVA irradiation for 15 min results in encapsulated AuNPs of 2.8±1.6 nm in diameter that are primarily dispersed in the aqueous interior of the liposomes.

  20. Current trends in the use of liposomes for tumor targeting.

    PubMed

    Deshpande, Pranali P; Biswas, Swati; Torchilin, Vladimir P

    2013-09-01

    The use of liposomes for drug delivery began early in the history of pharmaceutical nanocarriers. These nanosized, lipid bilayered vesicles have become popular as drug delivery systems owing to their efficiency, biocompatibility, nonimmunogenicity, enhanced solubility of chemotherapeutic agents and their ability to encapsulate a wide array of drugs. Passive and ligand-mediated active targeting promote tumor specificity with diminished adverse off-target effects. The current field of liposomes focuses on both clinical and diagnostic applications. Recent efforts have concentrated on the development of multifunctional liposomes that target cells and cellular organelles with a single delivery system. This review discusses the recent advances in liposome research in tumor targeting. PMID:23914966

  1. Development of risperidone liposomes for brain targeting through intranasal route.

    PubMed

    Narayan, Reema; Singh, Mohan; Ranjan, OmPrakash; Nayak, Yogendra; Garg, Sanjay; Shavi, Gopal V; Nayak, Usha Y

    2016-10-15

    The present paper is aimed at development of functionalized risperidone liposomes for brain targeting through nasal route for effective therapeutic management of schizophrenia. The risperidone liposomes were prepared by thin film hydration method. Various parameters such as lipid ratio and lipid to drug ratio were optimized by using Design-Expert(®) Software to obtain high entrapment with minimum vesicle size. The surface of the optimized liposomes was modified by coating stearylamine and MPEG-DSPE for enhanced penetration to the brain. The formulations were evaluated for vesicle size, zeta potential, and entrapment efficiency. The morphology was studied by Transmission Electron Microscopy (TEM). In vivo efficacy was assessed by performing pharmacokinetic study in Wistar albino rats following intranasal administration of the formulations in comparison to intravenous bolus administration of pure drug. The mean vesicle size of optimized liposomes ranged from 90 to 100nm with low polydispersity index (<0.5). The entrapment efficiency of optimized liposomes was between 50 and 60%, functionalized liposomes showed maximum entrapment. The TEM images showed predominantly spherical vesicles with smooth bilayered surface. All formulations showed prolonged diffusion controlled drug release. The in vivo results showed that liposomal formulations provided enhanced brain exposure. Among the formulations studied, PEGylated liposomes (LP-16) had shown greater uptake of risperidone into the brain than plasma. High brain targeting efficiency index for LP-16 indicating preferential transport of the drug to brain. The study demonstrated successful formulation of surface modified risperidone liposomes for nasal delivery with brain targeting potential.

  2. Development of risperidone liposomes for brain targeting through intranasal route.

    PubMed

    Narayan, Reema; Singh, Mohan; Ranjan, OmPrakash; Nayak, Yogendra; Garg, Sanjay; Shavi, Gopal V; Nayak, Usha Y

    2016-10-15

    The present paper is aimed at development of functionalized risperidone liposomes for brain targeting through nasal route for effective therapeutic management of schizophrenia. The risperidone liposomes were prepared by thin film hydration method. Various parameters such as lipid ratio and lipid to drug ratio were optimized by using Design-Expert(®) Software to obtain high entrapment with minimum vesicle size. The surface of the optimized liposomes was modified by coating stearylamine and MPEG-DSPE for enhanced penetration to the brain. The formulations were evaluated for vesicle size, zeta potential, and entrapment efficiency. The morphology was studied by Transmission Electron Microscopy (TEM). In vivo efficacy was assessed by performing pharmacokinetic study in Wistar albino rats following intranasal administration of the formulations in comparison to intravenous bolus administration of pure drug. The mean vesicle size of optimized liposomes ranged from 90 to 100nm with low polydispersity index (<0.5). The entrapment efficiency of optimized liposomes was between 50 and 60%, functionalized liposomes showed maximum entrapment. The TEM images showed predominantly spherical vesicles with smooth bilayered surface. All formulations showed prolonged diffusion controlled drug release. The in vivo results showed that liposomal formulations provided enhanced brain exposure. Among the formulations studied, PEGylated liposomes (LP-16) had shown greater uptake of risperidone into the brain than plasma. High brain targeting efficiency index for LP-16 indicating preferential transport of the drug to brain. The study demonstrated successful formulation of surface modified risperidone liposomes for nasal delivery with brain targeting potential. PMID:27593571

  3. Application of long-circulating liposomes to cancer photodynamic therapy.

    PubMed

    Oku, N; Saito, N; Namba, Y; Tsukada, H; Dolphin, D; Okada, S

    1997-06-01

    Photodynamic therapy (PDT) as a cancer treatment is notable for its quite low side effects in comparison with those of chemotherapy and radiotherapy. However, the accumulation of porphyrin derivatives used in PDT into tumor tissues is rather low. Since long-circulating liposomes are known to accumulate passively into tumor tissues, we liposomalized a porphyrin derivative, benzoporphyrin derivative monoacid ring A (BPD-MA), and used these liposomes to investigate the usefulness of PDT for tumor-bearing mice. BPD-MA was liposomalized into glucuronate-modified liposomes, which are known to be long-circulating. These liposomes were injected i.v. into Balb/c mice bearing Meth A sarcoma, and tumor regression and survival time were monitored after irradiation with laser light. Tumor regression and complete curing of tumor (80% cure rate by the treatment with 6 mg/kg BPD-MA) were observed when long circulating liposomalized BPD-MA was injected and laser-irradiated. In contrast, only a 20% cure rate was obtained when the animals were treated with BPD-MA solution or BPD-MA entrapped in conventional liposomes. These results suggest that a long-circulating liposomal formulation of photo-sensitive agents is useful for PDT.

  4. Liposomal nanoparticles encapsulating iloprost exhibit enhanced vasodilation in pulmonary arteries

    PubMed Central

    Jain, Pritesh P; Leber, Regina; Nagaraj, Chandran; Leitinger, Gerd; Lehofer, Bernhard; Olschewski, Horst; Olschewski, Andrea; Prassl, Ruth; Marsh, Leigh M

    2014-01-01

    Prostacyclin analogues are standard therapeutic options for vasoconstrictive diseases, including pulmonary hypertension and Raynaud’s phenomenon. Although effective, these treatment strategies are expensive and have several side effects. To improve drug efficiency, we tested liposomal nanoparticles as carrier systems. In this study, we synthesized liposomal nanoparticles tailored for the prostacyclin analogue iloprost and evaluated their pharmacologic efficacy on mouse intrapulmonary arteries, using a wire myograph. The use of cationic lipids, stearylamine, or 1,2-di-(9Z-octadecenoyl)-3-trimethylammonium-propane (DOTAP) in liposomes promoted iloprost encapsulation to at least 50%. The addition of cholesterol modestly reduced iloprost encapsulation. The liposomal nanoparticle formulations were tested for toxicity and pharmacologic efficacy in vivo and ex vivo, respectively. The liposomes did not affect the viability of human pulmonary artery smooth muscle cells. Compared with an equivalent concentration of free iloprost, four out of the six polymer-coated liposomal formulations exhibited significantly enhanced vasodilation of mouse pulmonary arteries. Iloprost that was encapsulated in liposomes containing the polymer polyethylene glycol exhibited concentration-dependent relaxation of arteries. Strikingly, half the concentration of iloprost in liposomes elicited similar pharmacologic efficacy as nonencapsulated iloprost. Cationic liposomes can encapsulate iloprost with high efficacy and can serve as potential iloprost carriers to improve its therapeutic efficacy. PMID:25045260

  5. Effect of vehicle on topical liposomal drug delivery: petrolatum bases.

    PubMed

    Foldvari, M

    1996-01-01

    Liposornes used for topical applications are often incorporated into a vehicle to achieve suitable viscosity and application properties. The effect of incorporation of liposomes into white petrolatum as a possible dermatological base was investigated. A number of formulae were developed to determine the type of petrolatum base that would be compatible with the liposomes. The physical appearance and stability of the vaseline-liposome (VL) preparations were determined by organoleptic analysis and microscopy. The effect of petrolatum base on the drug release from the liposomes was determined in a flow-through diffusion cell system using a model silastic polymer membrane as barrier. A base containing white petrolatum 46.7% (w/w), stearyl alcohol 6.7% (w/w), cholesterol 13.3 (w/w), Tween 80 16.7% (w/w) and Span 16.7% (w/w) was selected for diffusion studies, since the mixture of this base and liposome preparation, at 1:1.9 (w/w) ratios, provided a stable, dermatologically acceptable dosage form, in which the liposomes were uniformly distributed and their structures were preserved. Diffusion studies showed that the drug release rate decreases 2.5x when the liposomes are incorporated into the vaseline base; however, after a temporary decrease they seem to extend the duration of release beyond that of the original liposomal formula. These studies revealed a possibility of using white petrolatum in the topical application of liposomes.

  6. Application of long-circulating liposomes to cancer photodynamic therapy.

    PubMed

    Oku, N; Saito, N; Namba, Y; Tsukada, H; Dolphin, D; Okada, S

    1997-06-01

    Photodynamic therapy (PDT) as a cancer treatment is notable for its quite low side effects in comparison with those of chemotherapy and radiotherapy. However, the accumulation of porphyrin derivatives used in PDT into tumor tissues is rather low. Since long-circulating liposomes are known to accumulate passively into tumor tissues, we liposomalized a porphyrin derivative, benzoporphyrin derivative monoacid ring A (BPD-MA), and used these liposomes to investigate the usefulness of PDT for tumor-bearing mice. BPD-MA was liposomalized into glucuronate-modified liposomes, which are known to be long-circulating. These liposomes were injected i.v. into Balb/c mice bearing Meth A sarcoma, and tumor regression and survival time were monitored after irradiation with laser light. Tumor regression and complete curing of tumor (80% cure rate by the treatment with 6 mg/kg BPD-MA) were observed when long circulating liposomalized BPD-MA was injected and laser-irradiated. In contrast, only a 20% cure rate was obtained when the animals were treated with BPD-MA solution or BPD-MA entrapped in conventional liposomes. These results suggest that a long-circulating liposomal formulation of photo-sensitive agents is useful for PDT. PMID:9212988

  7. pH-Triggered Echogenicity and Contents Release from Liposomes

    PubMed Central

    2015-01-01

    Liposomes are representative lipid nanoparticles widely used for delivering anticancer drugs, DNA fragments, or siRNA to cancer cells. Upon targeting, various internal and external triggers have been used to increase the rate for contents release from the liposomes. Among the internal triggers, decreased pH within the cellular lysosomes has been successfully used to enhance the rate for releasing contents. However, imparting pH sensitivity to liposomes requires the synthesis of specialized lipids with structures that are substantially modified at a reduced pH. Herein, we report an alternative strategy to render liposomes pH sensitive by encapsulating a precursor which generates gas bubbles in situ in response to acidic pH. The disturbance created by the escaping gas bubbles leads to the rapid release of the encapsulated contents from the liposomes. Atomic force microscopic studies indicate that the liposomal structure is destroyed at a reduced pH. The gas bubbles also render the liposomes echogenic, allowing ultrasound imaging. To demonstrate the applicability of this strategy, we have successfully targeted doxorubicin-encapsulated liposomes to the pancreatic ductal carcinoma cells that overexpress the folate receptor on the surface. In response to the decreased pH in the lysosomes, the encapsulated anticancer drug is efficiently released. Contents released from these liposomes are further enhanced by the application of continuous wave ultrasound (1 MHz), resulting in substantially reduced viability for the pancreatic cancer cells (14%). PMID:25271780

  8. Preparation and pH stability of ferrous glycinate liposomes.

    PubMed

    Ding, Baomiao; Xia, Shuqin; Hayat, Khizar; Zhang, Xiaoming

    2009-04-01

    Ferrous glycinate liposomes were prepared by reverse phase evaporation method. The effects of cholesterol, Tween 80, ferrous glycinate concentration, hydrating medium, pH of hydrating medium, and sonication strength on the encapsulation efficiency of liposomes were investigated. Encapsulation efficiency was significantly influenced by the different technique parameters. Ferrous glycinate liposomes might be obtained with high encapsulation efficiency of 84.80% under the conditions of optimized technique parameters. The zeta potential and average particle size of liposomes in the hydrating medium of pH 7.0 were 9.6 mV and 559.2 nm, respectively. The release property of ferrous glycinate liposomes in vitro was investigated in simulated gastrointestinal juice. A small amount of ferrous glycinate was released from liposomes in the first 4 h in simulated gastrointestinal juice. The mean diameters of liposomes increased from 559.2 to 692.9, 677.8, and 599.3 nm after incubation in simulated gastrointestinal juice of pH 1.3, 7.5, and 7.5 in the presence of bile salts, respectively. Results showed that the stability of ferrous glycinate in strong acid environment was greatly improved by encapsulation in liposomes, which protected ferrous glycinate from disrupting the extracapsular environment by lipid bilayer. The bioavailability of ferrous glycinate, as the iron source for biological activity including hemoglobin formation, may be increased. The ferrous glycinate liposomes may be a kind of promising iron fortifier. PMID:19253959

  9. The preparation and characterization of gas bubble containing liposomes.

    PubMed

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

    2005-01-01

    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.

  10. On the interaction of the liposomal membrane with blood components.

    PubMed

    Miller, I F; Hoag, J M; Rooney, M W

    1992-01-01

    Liposome-encapsulated hemoglobin (LEH) has been shown to be a viable candidate as a blood replacement. However, few data have been presented as to how LEH interacts with normal blood components. Liposomes were prepared from egg lecithin, cholesterol, and dicetyl phosphate or phosphatidic acid, and mixed with fresh blood plasma or whole blood. Erythrocyte osmotic fragility, prothrombin time (extrinsic coagulation efficiency), activated partial thromboplastin time (intrinsic coagulation efficiency), plasma clot stability in urea (fibrin stabilizing factor), and clot retraction (platelet activation) were measured. Although liposomes were found to bind extensively to erythrocytes, all tests indicated that the liposomes had no significant adverse effects, provided that normal levels of plasma Ca++ were maintained. The ability of liposomes to absorb Ca++ from the plasma was related directly to the amount of dicetyl phosphate or phosphatidic acid present and thus, presumably, to the presence of negatively charged species in the membrane. The mechanics of deformation of the LEH membrane were investigated by encapsulating Hemoglobin S in liposomes. Liposomes containing Hemoglobin S were found to sickle when deoxygenated, but not liposomes containing normal hemoglobin. Shape analysis of sickled liposomes yielded a deforming stress of 10(6) dynes/cm2, about 50 times greater than the reported limit for shear elasticity of the erythrocyte membrane. PMID:1391486

  11. Current trends in the use of liposomes for tumor targeting

    PubMed Central

    Deshpande, Pranali P; Biswas, Swati; Torchilin, Vladimir P

    2013-01-01

    The use of liposomes for drug delivery began early in the history of pharmaceutical nanocarriers. These nanosized, lipid bilayered vesicles have become popular as drug delivery systems owing to their efficiency, biocompatibility, nonimmunogenicity, enhanced solubility of chemotherapeutic agents and their ability to encapsulate a wide array of drugs. Passive and ligand-mediated active targeting promote tumor specificity with diminished adverse off-target effects. The current field of liposomes focuses on both clinical and diagnostic applications. Recent efforts have concentrated on the development of multifunctional liposomes that target cells and cellular organelles with a single delivery system. This review discusses the recent advances in liposome research in tumor targeting. PMID:23914966

  12. The Targeted-liposome Delivery System of Antitumor Drugs.

    PubMed

    Wu, Wei-dang; Yi, Xiu-lin; Jiang, Li-xin; Li, Ya-zhuo; Gao, Jing; Zeng, Yong; Yi, Rong-da; Dai, Li-peng; Li, Wei; Ci, Xiao-yan; Si, Duan-yun; Liu, Chang-xiao

    2015-01-01

    The liposome delivery system has been intensively explored as novel drug delivery system (DDS) for antitumor drugs, due to its safety, selective cytotoxicity, long circulation and slow elimination in blood, which is favorable for cancer therapy. The liposome-based chemotherapeutics are used to treat a variety of cancers to enhance the therapeutic index of antitumor drugs. Here, the author reviewed the important targets for cancer therapy and the pharmacokinetic behavior of liposomal drugs in vivo, as well as the application of the targeting liposomal system in cancer therapy. Considering further application for clinical use, the great challenges of the liposome-based delivery system were also proposed as follows: 1) prepare stealth liposome with steric stabilization and further enhance the therapeutic effects and safety; 2) explore more safe clinical targets and complementary or different types of targeting liposome; 3) thirdly, more investment is needed on the research of pharmacokinetics of the elements such as the ligands (antibody), PEG and lipids of liposome delivery system as well as safety evaluation. Considering the complex process of the liposomal encapsulation drugs in vivo, the author inferred that there are maybe different forms of the encapsulation drug to be internalized by the tumor tissues at the same time and space, although there are little reports on it. PMID:26652257

  13. Liposomes in tissue engineering and regenerative medicine

    PubMed Central

    Monteiro, Nelson; Martins, Albino; Reis, Rui L.; Neves, Nuno M.

    2014-01-01

    Liposomes are vesicular structures made of lipids that are formed in aqueous solutions. Structurally, they resemble the lipid membrane of living cells. Therefore, they have been widely investigated, since the 1960s, as models to study the cell membrane, and as carriers for protection and/or delivery of bioactive agents. They have been used in different areas of research including vaccines, imaging, applications in cosmetics and tissue engineering. Tissue engineering is defined as a strategy for promoting the regeneration of tissues for the human body. This strategy may involve the coordinated application of defined cell types with structured biomaterial scaffolds to produce living structures. To create a new tissue, based on this strategy, a controlled stimulation of cultured cells is needed, through a systematic combination of bioactive agents and mechanical signals. In this review, we highlight the potential role of liposomes as a platform for the sustained and local delivery of bioactive agents for tissue engineering and regenerative medicine approaches. PMID:25401172

  14. The reconstitution of actin polymerization on liposomes.

    PubMed

    Stamnes, Mark; Xu, Weidong

    2010-01-01

    Membrane-associated actin polymerization is of considerable interest due to its role in cell migration and the motility of intracellular organelles. Intensive research efforts are underway to investigate the physiological role of membrane-associated actin as well as the regulation and mechanics of actin assembly. Branched actin polymerization on membranes is catalyzed by the Arp2/3 complex. Signaling events leading to the activation of the guanosine triphosphate (GTP)-binding protein Cdc42 stimulate Arp2/3-dependent actin polymerization. We have studied the role of Cdc42 at the Golgi apparatus in part by reconstituting actin polymerization on isolated Golgi membranes and on liposomes. In this manner, we showed that cytosolic proteins are sufficient for actin assembly on a phospholipid bilayer. Here we describe methods for the cell-free reconstitution of membrane-associated actin polymerization using liposomes and brain cytosol.

  15. Studying mechanosensitive ion channels using liposomes.

    PubMed

    Martinac, Boris; Rohde, Paul R; Battle, Andrew R; Petrov, Evgeny; Pal, Prithwish; Foo, Alexander Fook; Vásquez, Valeria; Huynh, Thuan; Kloda, Anna

    2010-01-01

    Mechanosensitive (MS) ion channels are the primary molecular transducers of mechanical force into electrical and/or chemical intracellular signals in living cells. They have been implicated in innumerable mechanosensory physiological processes including touch and pain sensation, hearing, blood pressure control, micturition, cell volume regulation, tissue growth, or cellular turgor control. Much of what we know about the basic physical principles underlying the conversion of mechanical force acting upon membranes of living cells into conformational changes of MS channels comes from studies of MS channels reconstituted into artificial liposomes. Using bacterial MS channels as a model, we have shown by reconstituting these channels into liposomes that there is a close relationship between the physico-chemical properties of the lipid bilayer and structural dynamics bringing about the function of these channels.

  16. Phase structure of liposome in lipid mixtures.

    PubMed

    Zhang, Tianxi; Li, Yuzhuo; Mueller, Anja

    2011-11-01

    Gas microbubbles present in ultrasound imaging contrast agents are stabilized by lipid aggregates that typically contain a mixture of lipids. In this study, the phase structure of the lipid mixtures that contained two or three lipids was investigated using three different methods: dynamic light scattering, (1)H NMR, and microfluidity measurements with fluorescence probes. Three lipids that are commonly present in imaging agents (DPPC, DPPE-PEG, and DPPA) were used. Two types of systems, two-lipid model systems and simulated imaging systems were investigated. The results show that liposomes were the dominant aggregates in all the samples studied. The polar PEG side chains from the PEGylated lipid lead to the formation of micelles and micellar aggregates in small sizes. In the ternary lipid systems, almost all the lipids were present in bilayers with micelles absent and free lipids at very low concentration. These results suggest that liposomes, not micelles, contribute to the stabilization of microbubbles in an ultrasound imaging contrast agent.

  17. Synthesis of the iron phthalocyaninate radical cation μ-nitrido dimer and its interaction with hydrogen peroxide

    NASA Astrophysics Data System (ADS)

    Grishina, E. S.; Makarova, A. S.; Kudrik, E. V.; Makarov, S. V.; Koifman, O. I.

    2016-03-01

    The iron phthalocyaninate μ-nitrido dimer radical cation, as well as the μ-nitrido dimer complexes of iron phthalocyaninate, was found to have high catalytic activity in the oxidation of organic compounds. It was concluded that this compound is of interest as a model of active intermediates—catalase and oxidase enzymes.

  18. Liposomes as drug carriers for oral ulcers.

    PubMed

    Harsanyi, B B; Hilchie, J C; Mezei, M

    1986-09-01

    The aim of this study was to test the potential of liposomes as drug carriers to the ulcerated oral mucosa. Radioactive triamcinolone acetonide palmitate (3H-TRMAp) was encapsulated in large multilamellar lipid vesicles and served as the test lotion. 3H-TRMAp in solution served as control. Forty-six hamsters were divided into three groups. In group I, multiple confluent ulcers in both cheek pouches were treated by topical application. In group II, single ulcers on the cheeks were treated by intramucosal injection. In group III, multiple confluent ulcers were produced in the cheek pouch on one side, with a single ulcer in the contralateral cheek pouch; no drug was applied, and the tissues were prepared for histology. Hamsters were killed at three and 24 hours, respectively, after treatment. Pouches were divided into ulcerated and intact adjacent mucosa. Cheeks were divided into ulcerated mucosa and distant mucosa. Drug levels in the four mucosal portions as well as in the blood, liver, spleen, brain, and thalamic region were determined by radioactive tracer technique. At three hours, liposomal drug concentrations were lower than in control animals in the brain and the thalamic region. At 24 hours, liposomal drug values were higher than in control animals in the ulcerated mucosa and lower than in control animals in the thalamic region. Mean drug concentrations in the ulcerated mucosa were higher in group II than group I. The results parallel those of Mezei and Gulasekharam (1980, 1982); liposomes increase local and decrease systemic drug concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

  19. Effect of liposomal fluidity on skin permeation of sodium fluorescein entrapped in liposomes.

    PubMed

    Subongkot, Thirapit; Ngawhirunpat, Tanasait

    2015-01-01

    The purpose of this study was to investigate the effect of ultradeformable liposome components, Tween 20 and terpenes, on vesicle fluidity. The fluidity was evaluated by electron spin resonance spectroscopy using 5-doxyl stearic acid and 16-doxyl stearic acid as spin labels for phospholipid bilayer fluidity at the C5 atom of the acyl chain near the polar head group (hydrophilic region) and the C16 atom of the acyl chain (lipophilic region), respectively. The electron spin resonance study revealed that Tween 20 increased the fluidity at the C5 atom of the acyl chain, whereas terpenes increased the fluidity at the C16 atom of the acyl chain of the phospholipid bilayer. The increase in liposomal fluidity resulted in the increased skin penetration of sodium fluorescein. Confocal laser scanning microscopy showed that ultradeformable liposomes with terpenes increase the skin penetration of sodium fluorescein by enhancing hair follicle penetration.

  20. Effect of liposomal fluidity on skin permeation of sodium fluorescein entrapped in liposomes.

    PubMed

    Subongkot, Thirapit; Ngawhirunpat, Tanasait

    2015-01-01

    The purpose of this study was to investigate the effect of ultradeformable liposome components, Tween 20 and terpenes, on vesicle fluidity. The fluidity was evaluated by electron spin resonance spectroscopy using 5-doxyl stearic acid and 16-doxyl stearic acid as spin labels for phospholipid bilayer fluidity at the C5 atom of the acyl chain near the polar head group (hydrophilic region) and the C16 atom of the acyl chain (lipophilic region), respectively. The electron spin resonance study revealed that Tween 20 increased the fluidity at the C5 atom of the acyl chain, whereas terpenes increased the fluidity at the C16 atom of the acyl chain of the phospholipid bilayer. The increase in liposomal fluidity resulted in the increased skin penetration of sodium fluorescein. Confocal laser scanning microscopy showed that ultradeformable liposomes with terpenes increase the skin penetration of sodium fluorescein by enhancing hair follicle penetration. PMID:26229462

  1. Effect of liposomal fluidity on skin permeation of sodium fluorescein entrapped in liposomes

    PubMed Central

    Subongkot, Thirapit; Ngawhirunpat, Tanasait

    2015-01-01

    The purpose of this study was to investigate the effect of ultradeformable liposome components, Tween 20 and terpenes, on vesicle fluidity. The fluidity was evaluated by electron spin resonance spectroscopy using 5-doxyl stearic acid and 16-doxyl stearic acid as spin labels for phospholipid bilayer fluidity at the C5 atom of the acyl chain near the polar head group (hydrophilic region) and the C16 atom of the acyl chain (lipophilic region), respectively. The electron spin resonance study revealed that Tween 20 increased the fluidity at the C5 atom of the acyl chain, whereas terpenes increased the fluidity at the C16 atom of the acyl chain of the phospholipid bilayer. The increase in liposomal fluidity resulted in the increased skin penetration of sodium fluorescein. Confocal laser scanning microscopy showed that ultradeformable liposomes with terpenes increase the skin penetration of sodium fluorescein by enhancing hair follicle penetration. PMID:26229462

  2. Phototriggerable Liposomes: Current Research and Future Perspectives

    PubMed Central

    Puri, Anu

    2013-01-01

    The field of cancer nanomedicine is considered a promising area for improved delivery of bioactive molecules including drugs, pharmaceutical agents and nucleic acids. Among these, drug delivery technology has made discernible progress in recent years and the areas that warrant further focus and consideration towards technological developments have also been recognized. Development of viable methods for on-demand spatial and temporal release of entrapped drugs from the nanocarriers is an arena that is likely to enhance the clinical suitability of drug-loaded nanocarriers. One such approach, which utilizes light as the external stimulus to disrupt and/or destabilize drug-loaded nanoparticles, will be the discussion platform of this article. Although several phototriggerable nanocarriers are currently under development, I will limit this review to the phototriggerable liposomes that have demonstrated promise in the cell culture systems at least (but not the last). The topics covered in this review include (i) a brief summary of various phototriggerable nanocarriers; (ii) an overview of the application of liposomes to deliver payload of photosensitizers and associated technologies; (iii) the design considerations of photoactivable lipid molecules and the chemical considerations and mechanisms of phototriggering of liposomal lipids; (iv) limitations and future directions for in vivo, clinically viable triggered drug delivery approaches and potential novel photoactivation strategies will be discussed. PMID:24662363

  3. Liposomes by quasielastic light scattering and spectroturbidimetry

    NASA Astrophysics Data System (ADS)

    Khlebtsov, Boris N.; Khlebtsov, Nikolai G.; Shchyogolev, Sergei Y.

    2002-07-01

    A variant of the experimental implementation of the quasi- elastic light scattering (QELS) method for determining the average particle size in liposome suspensions in the homodyne mode was considered. The aim of the investigations was to compare the data obtained with the result of a version of the method of spectroturbidimetry (STM) previously developed to determine the size and shell thickness of liposomes. For determination of the corresponding correlation functional, an experimental setup was used that was base don a helium-neon laser with a computer sound card as the analog-digital converter. Monodisperse suspension of latexes and colloidal gold as well as E. coli cell suspension were used as the test objects. The tests showed good accuracy of the QELS determination of the particle diameter d in the region of d < 100. Below this boundary, the accuracy of the particle size determination is limited by the relatively low resolving capacity of the analog-digital converter of the given type. It was established that the results of the determination of the average particle size in liposome polydisperse suspension obtained by QELS and STM were in satisfactory agreement.

  4. Oxygen Measurements in Liposome Encapsulated Hemoglobin

    NASA Astrophysics Data System (ADS)

    Phiri, Joshua Benjamin

    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.

  5. Elaboration of ammonia gas sensors based on electrodeposited polypyrrole--cobalt phthalocyanine hybrid films.

    PubMed

    Patois, Tilia; Sanchez, Jean-Baptiste; Berger, Franck; Fievet, Patrick; Segut, Olivier; Moutarlier, Virginie; Bouvet, Marcel; Lakard, Boris

    2013-12-15

    The electrochemical incorporation of a sulfonated cobalt phthalocyanine (sCoPc) in conducting polypyrrole (PPy) was done, in the presence or absence of LiClO4, in order to use the resulting hybrid material for the sensing of ammonia. After electrochemical deposition, the morphological features and structural properties of polypyrrole/phthalocyanine hybrid films were investigated and compared to those of polypyrrole films. A gas sensor consisting in platinum microelectrodes arrays was fabricated using silicon microtechnologies, and the polypyrrole and polypyrrole/phthalocyanine films were electrochemically deposited on the platinum microelectrodes arrays of this gas sensor. When exposed to ammonia, polymer-based gas sensors exhibited a decrease in conductance due to the electron exchange between ammonia and sensitive polymer-based layer. The characteristics of the gas sensors (response time, response amplitude, reversibility) were studied for ammonia concentrations varying from 1 ppm to 100 ppm. Polypyrrole/phthalocyanine films exhibited a high sensitivity and low detection limit to ammonia as well as a fast and reproducible response at room temperature. The response to ammonia exposition of polypyrrole films was found to be strongly enhanced thanks to the incorporation of the phthalocyanine in the polypyrrole matrix.

  6. Evaluation of electrostatic binding of PAMAM dendrimers and charged phthalocyanines by fluorescence correlation spectroscopy.

    PubMed

    Garcia-Fernandez, Emilio; Paulo, Pedro M R; Costa, Sílvia M B

    2015-02-14

    We have assessed host-guest interactions between PAMAM dendrimers and charged phthalocyanine probes by Fluorescence Correlation Spectroscopy (FCS). Our results show strong binding in water at low ionic strength with an affinity that decreases from KB ∼ 10(9) to 10(8) M(-1) upon decreasing the phthalocyanine charge of z = -4, -2 and -1. The binding affinity also decreases significantly upon salt addition leading to KB values of ca. 10(5)-10(6) M(-1). The changes of binding affinity probed by varying the phthalocyanine charge, and by changing the ionic strength or pH conditions, allowed us to evaluate the electrostatic contribution (Kel) in dendrimer-phthalocyanine interactions. In particular, this approach afforded values of electrostatic potential for PAMAM dendrimers in water at low ionic strength and at dendrimer concentrations in the nanomolar range. The electrostatic potential of PAMAM generations 4 and 7 are around 50 mV in close agreement with theoretical estimates using the Poisson-Boltzmann cell model. Interestingly, the nonelectrostatic binding is significant and contributes even more than electrostatic binding to dendrimer-phthalocyanine interactions. The nonelectrostatic binding contributes to an affinity of KB above 10(5) M(-1), as measured under conditions of low dendrimer charge and high ionic strength, which makes these dendrimers promising hosts as drug carriers.

  7. Synthesis, spectral, and electrochemical characterization of the first arsenic(V)-phthalocyanines.

    PubMed

    Isago, Hiroaki; Kagaya, Yutaka

    2012-08-01

    The first arsenic(V)-phthalocyanines, [As(tbpc)X(2)](+), where tbpc denotes tetra(tert-butyl)phthalocyaninate, C(48)H(48)N(8)(2-) and X = F, Cl, and Br) have been prepared through an appropriate oxidative addition process to a highly soluble arsenic(III) derivative, [As(tbpc)](+). Among them, [As(tbpc)F(2)](+) has been isolated as PF(6)(-) salt. Unlike conventional metal derivatives of phthalocyanines, they show a significantly red-shifted (by >1000 cm(-1)) Q-band and facile reduction of the macrocyclic ligand (redox potentials for [As(tbpc)F(2)](+) have been determined by cyclic voltammetry; 1.13 V vs ferricinium(+)/ferrocene (tbpc(-/2-)), -0.45 V (tbpc(2-/3-)), and -0.90 V (tbpc(3-/4-)), of which the values are anodically shifted by about 1 V) as compared to those of conventional phthalocyanines. Although the anomaly in their spectral and electrochemical properties is similar to that of the known antimony analogues, the arsenic-phthalocyanines have been found less stable.

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

    SciTech Connect

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

    2010-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-11-01

    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.

  10. Formation of bovine serum albumin associates with zinc tetra(4,4'-carboxy)phenylamino- and tetra-(4,4'-carboxy)phenoxy phthalocyanines in aqueous-organic solutions at 298 K

    NASA Astrophysics Data System (ADS)

    Lebedeva, N. Sh.; Popova, T. E.; Mal'kova, E. A.; Gubarev, Yu. A.

    2013-12-01

    The states of water-soluble complexes of zinc phthalocyanine containing -O-C6H4-COONa and -NH-C6H4-COONa substituents in aqueous and organic media are studied. The type of dimerization is determined for each phthalocyanine. Phthalocyanine interaction with bovine serum albumin is studied with respect to the association equilibria. It is shown that phthalocyanines are localized in protein subdomains IB and IIA, and the interaction between protein and phthalocyanines is of a multicenter character.

  11. Synthesis of phthalocyanine doped sol-gel materials

    NASA Technical Reports Server (NTRS)

    Dunn, Bruce

    1993-01-01

    The synthesis of sol-gel silica materials doped with three different types of metallophthalocyanines has been studied. Homogeneous materials of good optical quality were prepared and the first optical limiting measurements of dyes in sol-gel hosts were carried out. The properties of these solid state limiters are similar to limiters based on phthalocyanine (Pc) in solution. Sol-gel silica materials containing copper, tin and germanium phthalocyanines were investigated. The initial step in all cases was to prepare silica sols by the sonogel method using tetramethoxy silane (TMOS), HCl and distilled water. Thereafter, the synthesis depended upon the specific Pc and its solubility characteristics. Copper phthalocyanine tetrasulfonic acid tetra sodium salt (CuPc4S) is soluble in water and various doping levels (1 x 10 (exp -4) M to 1 x 10 (exp -5) M) were added to the sol. The group IV Pc's, SnPc(OSi(n-hexyl)3)2 and GePc(OSi(n-hexyl)3)2, are insoluble in water and the process was changed accordingly. In these cases, the compounds were dissolved in THF and then added to the sol. The Pc concentration in the sol was 2 x 10(exp -5)M. The samples were then aged and dried in the standard method of making xerogel monoliths. Comparative nanosecond optical limiting experiments were performed on silica xerogels that were doped with the different metallophthalocyanines. The ratio of the net excited state absorption cross section (sigma(sub e)) to the ground state cross section (sigma(sub g)) is an important figure of merit that is used to characterize these materials. By this standard the SnPc sample exhibits the best limiting for the Pc doped sol-gel materials. Its cross section ratio of 19 compares favorably with the value of 22 that was measured in toluene. The GePc materials appear to not be as useful as those containing SnPc. The GePc doped solids exhibit a higher onset energy (2.5 mj and lower cross section ratio, 7. The CuPc4S sol-gel material has a still lower cross

  12. Liposomal nanoparticles as a drug delivery vehicle against osteosarcoma

    NASA Astrophysics Data System (ADS)

    Dhule, Santosh Subhashrao

    The delivery of curcumin, a broad-spectrum anticancer drug, has been explored in the form of liposomal nanoparticles to treat osteosarcoma (OS). Curcumin is water insoluble and an effective delivery route is through encapsulation in cyclodextrins followed by a second encapsulation in liposomes. Liposomal curcumin's potential was evaluated against cancer models of mesenchymal (OS) and epithelial origin (breast cancer). The resulting 2-Hydroxypropyl-gamma-cyclodextrin/curcumin - liposome complex shows promising anticancer potential both in vitro and in vivo against KHOS OS cell line and MCF-7 breast cancer cell line. An interesting aspect is that liposomal curcumin initiates the caspase cascade that leads to apoptotic cell death in vitro in comparison with DMSO-curcumin induced autophagic cell death. In addition, the efficiency of the liposomal curcumin formulation was confirmed in vivo using a xenograft OS model. Curcumin-loaded gamma-cyclodextrin liposomes indicate significant potential as delivery vehicles for the treatment of cancers of different tissue origin. The second part of this study examines the anti-tumor potential of curcumin and C6 ceramide (C6) against osteosarcoma cell lines when both are encapsulated in the bilayer of liposomal nanoparticles. Curcumin in combination with C6 showed 1.5 times enhanced cytotoxic effect in the case of MG-63 and KHOS OS cell lines, in comparison with systems with curcumin alone. Interestingly, C6-curcumin liposomes were found to be less toxic on untransformed human cells in comparison to OS cell lines. In addition, cell cycle assays on a KHOS cell line after treatment revealed that curcumin only liposomes induced G 2/M arrest by upregulation of cyclin B1, while C6 only liposomes induced G1 arrest by downregulation of cyclin D1. C6-curcumin liposomes induced G2/M arrest and showed a combined effect in the expression levels of cyclin D1 and cyclin B1. Using pegylated liposomes to increase the plasma half-life and tagging

  13. Characterization and stability of various liposome-encapsulated enoxacin formulations.

    PubMed

    Fang, J Y; Lin, H H; Hsu, L R; Tsai, Y H

    1997-09-01

    The necessity for antibacterial agents with greater intracellular efficacy has led to the development of endocytosable drug carriers such as liposomes. Enoxacin was selected as a model drug incorporated in various liposome formulations as a therapeutic dosage form using the ethanol injection method and freeze-drying. Liposomal behavior after preparation and stability test was characterized by determining the physicochemical properties of enoxacin encapsulation percent, vesicle size and turbidity. The non-phospholipid formulation of stratum corneum liposomes showed the highest encapsulation efficiency after preparation among nine liposomal formulations. The addition of dissacharides in liposomes also enhanced the encapsulation of enoxacin due to the protection of phospholipid bilayers during the freeze-drying process. The liposomes with negatively charged component and dissacharides showed lower enoxacin leakage after five weeks of storage at 45 degrees C, suggesting these formulations have high stability in long-term storage. The negative liposomes showed a different behavior than others in their decrease of size and turbidity during storage, possibly due to high surface charges of the negative formulation. Cholesterol stabilized bilayers interacted with plasma and high density lipoprotein (HDL) retained enoxacin in the vesicles. Nevertheless, liposomes with cholesterol caused a hydrolysis problem after incubation with normal saline. The formulation with trehalose not only showed high stability in storage but also in plasma and HDL. This suggested trehalose was useful to incorporate with phospholipids to produce a highly encapsulated and stabilized liposomes of enoxacin. This study also demonstrated that thought is required in utilizing turbidity as a direct index of liposomal vesicle size. PMID:9332003

  14. Characterization and stability of various liposome-encapsulated enoxacin formulations.

    PubMed

    Fang, J Y; Lin, H H; Hsu, L R; Tsai, Y H

    1997-09-01

    The necessity for antibacterial agents with greater intracellular efficacy has led to the development of endocytosable drug carriers such as liposomes. Enoxacin was selected as a model drug incorporated in various liposome formulations as a therapeutic dosage form using the ethanol injection method and freeze-drying. Liposomal behavior after preparation and stability test was characterized by determining the physicochemical properties of enoxacin encapsulation percent, vesicle size and turbidity. The non-phospholipid formulation of stratum corneum liposomes showed the highest encapsulation efficiency after preparation among nine liposomal formulations. The addition of dissacharides in liposomes also enhanced the encapsulation of enoxacin due to the protection of phospholipid bilayers during the freeze-drying process. The liposomes with negatively charged component and dissacharides showed lower enoxacin leakage after five weeks of storage at 45 degrees C, suggesting these formulations have high stability in long-term storage. The negative liposomes showed a different behavior than others in their decrease of size and turbidity during storage, possibly due to high surface charges of the negative formulation. Cholesterol stabilized bilayers interacted with plasma and high density lipoprotein (HDL) retained enoxacin in the vesicles. Nevertheless, liposomes with cholesterol caused a hydrolysis problem after incubation with normal saline. The formulation with trehalose not only showed high stability in storage but also in plasma and HDL. This suggested trehalose was useful to incorporate with phospholipids to produce a highly encapsulated and stabilized liposomes of enoxacin. This study also demonstrated that thought is required in utilizing turbidity as a direct index of liposomal vesicle size.

  15. Au nanorods modulated NIR fluorescence and singlet oxygen generation of water soluble dendritic zinc phthalocyanine.

    PubMed

    Zhou, Xuefei; He, Xiaohong; Wei, Shiliang; Jia, Kun; Liu, Xiaobo

    2016-11-15

    A novel cyano-terminated zinc phthalocyanine (ZnPc-CN) exhibiting visible near infrared (vis-NIR) emitting around 690nm in N,N-dimethylformamide (DMF) solvent has been synthesized. Furthermore, the peripheral cyano groups of newly synthesized zinc phthalocyanine were hydrolyzed in strong basic solution, leading to water soluble carboxylated zinc phthalocyanine (ZnPc-COOH) with completely quenched fluorescence in aqueous solution. Interestingly, we found that the NIR fluorescence of aqueous ZnPc-COOH was dramatically recovered in the presence of gold nanorods (Au NR), which was due to the alternation of ZnPc-COOH molecules self-assembling via electrostatic interaction between cetyltrimethylammonium bromide (CTAB) on the surface of Au NR and peripheral carboxyl of ZnPc-COOH. In addition, ZnPc-COOH/Au NR conjugates demonstrated an improved singlet oxygen generation, which could be served as potential bioimaging probe and photosensitizer for photodynamic therapy. PMID:27505278

  16. Modern synthetic tools toward the preparation of sophisticated phthalocyanine-based photoactive systems.

    PubMed

    Ragoussi, Maria-Eleni; Torres, Tomás

    2014-10-01

    Phthalocyanines are ideal components in a variety of electronic applications due to their extraordinary photophysical characteristics combined with their synthetic versatility and robustness. They have attracted substantial attention in recent decades and are now established building blocks of sophisticated molecular materials. Synthetically, a great deal of this progress is attributed to the use of modern synthetic tools, which gave rise to phthalocyanine-based systems that could not have been envisaged in the past. In particular, Pd-catalyzed cross-coupling reactions, together with other transition-metal-catalyzed procedures, "click" chemistry, and ruthenium metathesis have been employed extensively en route to an abundant range of elaborate phthalocyanine mono- and multicomponent photoactive architectures. Herein, we describe the synthesis of a selection of key examples that are representative in certain optoelectronic applications.

  17. [Synthesis, characterization and fluorescent properties of copper phthalocyanine derivates substituted by aliphatic alcohol].

    PubMed

    Zhang, Liang; Xu, Qing-Feng; Lu, Jian-Mei; Yao, She-Chun

    2007-04-01

    A series of copper phthalocyanine derivatives substituted by aliphatic chain were obtained by the reaction of tetra-formyl chloride copper phthalocyanine and aliphatic alcohol such as n-butyl alcohol, n-amyl alcohol, n-hexyl alcohol, n-caprylic alcohol and lauryl alcohol. IR, UV-Vis, elemental analysis and 1H NMR verified the structures and substituting degree. The solubility and the relationship between fluorescence and concentration and substituting group were studied in organic solution. It was confirmed that the solubility in organic solution was improved greatly, the fluorescence did not change in linear according to the concentration and the fluorescence of copper phthalocyanine derivatives substituted by the long alkyl was stronger than that substituted by the relatively short alkyl.

  18. Synthesis and characterization of novel phthalocyanines and evaluation of photodynamic therapy properties

    NASA Astrophysics Data System (ADS)

    Korkmaz, Aysun; Kahraman, Mehmet; Yilmaz, Yusuf

    2016-03-01

    In this study, phthalocyanine (Pc) compounds were synthesized and evaluated photophysical and photochemical properties for the possible application of PDT. Zinc is used as central atom for the Pc to obtain higher singlet oxygen production. The structures of the synthesized Pc are characterized by IR, UV-vis, 1H , elemental analysis and MS. The results demonstrated that the synthesized Pc is a good candidate for the PDT applications for the cancers. The synthesized Pc will be also bound covalently to the nano surface via -SH functional group that can contribute to the production of singlet oxygen amount carrying phthalocyanines having diamagnetic metal. Thus, phthalocyanine compounds and their derivatives having high wavelength (near-IR) absorption, high triplet quantum yields, triplet state lifetime of singlet oxygen allow us to use PDT applications effectively.

  19. Synthesis and Spectroscopic Evaluation of Two Novel Glycosylated Zinc(II)-Phthalocyanines.

    PubMed

    Bächle, Felix; Hanack, Michael; Ziegler, Thomas

    2015-10-09

    In continuation of our work on glycoconjugated phthalocyanines, two new water soluble, non-ionic zinc(II) phthalocyanines have been prepared and fully characterized by means of ¹H-NMR, 13C-NMR, MALDI-TOF, ESI-TOF, UV-Vis spectroscopy, emission spectroscopy and fluorescence lifetime measurements. The carbohydrate-containing phthalonitrile precursors were synthesized through a copper-catalyzed azide-alkyne cycloaddition (CuAAC). The 2-methoxyethoxymethyl protecting group (MEM) was used to protect the carbohydrate moieties. It resisted the harsh basic cyclotetramerization conditions and could be easily cleaved under mild acidic conditions. The glycoconjugated zinc(II) phthalocyanines described here have molar extinction coefficents εmax>10⁵ m(-1) cm(-1) and absorption maxima λ>680 nm, which make them attractive photosensitizers for photo-dynamic therapy.

  20. Effect of axial ligands on the molecular configurations, stability, reactivity, and photodynamic activities of silicon phthalocyanines.

    PubMed

    Luan, Liqiang; Ding, Lanlan; Shi, Jiawei; Fang, Wenjuan; Ni, Yuxing; Liu, Wei

    2014-12-01

    To demonstrate the effect of axial ligands on the structure-activity relationship, a series of axially substituted silicon phthalocyanines (SiPcs) have been synthesized with changes to the axial ligands. The reactivity of the axial ligand upon shielding by the phthalocyanine ring current, along with their stability, photophysical, and photodynamic therapy (PDT) activities were compared and evaluated for the first time. As revealed by single-crystal XRD analysis, rotation of the axial -OMe ligands was observed in SiPc 3, which resulted in two molecular configurations coexisting synchronously in both the solid and solution states and causing a split of the phthalocyanine α protons in the (1)H NMR spectra that is significantly different from all SiPcs reported so far. The remarkable photostability, good singlet oxygen quantum yield, and efficient in vitro photodynamic activity synergistically show that compound 3 is one of the most promising photosensitizers for PDT.

  1. Ultrafast dynamics of excited state of phenoxy-phthalocyanines in solution

    NASA Astrophysics Data System (ADS)

    Yao, Cheng-Bao; Yan, Xiao-Yan; Sun, Da-Wei; Sui, Yan-Li; Li, Jin; Sun, Wen-Jun; Li, Qiang-Hua; Yang, Shou-Bin

    2016-01-01

    Ultrafast dynamics of the excited state of 2,9,16,23-phenoxy-phthalocyanine (Pc1) and 2,9,16,23-phenoxy-phthalocyanine-zinc (Pc2) has been investigated using femtosecond transient absorption (TA) and time-resolved fluorescence (TRFL) techniques. The observed dynamics of femtosecond TA and TRFL experiments are similar, which demonstrated the intrinsic properties of the excitation and the relaxation processes in both kinds of phthalocyanines with two decay components. A multi level model has been proposed to explain the photophysical processes after Soret-band excitation. The results show that the fast decay component dynamics comes from the intramolecular vibrational relaxation, the slower ones from the internal conversion. The samples are expected to be a potential candidate for optical applications and photodynamic therapy.

  2. Synthesis and Spectroscopic Evaluation of Two Novel Glycosylated Zinc(II)-Phthalocyanines.

    PubMed

    Bächle, Felix; Hanack, Michael; Ziegler, Thomas

    2015-01-01

    In continuation of our work on glycoconjugated phthalocyanines, two new water soluble, non-ionic zinc(II) phthalocyanines have been prepared and fully characterized by means of ¹H-NMR, 13C-NMR, MALDI-TOF, ESI-TOF, UV-Vis spectroscopy, emission spectroscopy and fluorescence lifetime measurements. The carbohydrate-containing phthalonitrile precursors were synthesized through a copper-catalyzed azide-alkyne cycloaddition (CuAAC). The 2-methoxyethoxymethyl protecting group (MEM) was used to protect the carbohydrate moieties. It resisted the harsh basic cyclotetramerization conditions and could be easily cleaved under mild acidic conditions. The glycoconjugated zinc(II) phthalocyanines described here have molar extinction coefficents εmax>10⁵ m(-1) cm(-1) and absorption maxima λ>680 nm, which make them attractive photosensitizers for photo-dynamic therapy. PMID:26473808

  3. In situ laser Raman spectra of iron phthalocyanine adsorbed on copper and gold electrodes. [Electronic structure

    SciTech Connect

    Melendres, C.A.; Rios, C.B.; Feng, X.; McMasters, R.

    1983-01-01

    Raman spectra of iron phthalocyanine (FePc) and its tetrasulfonated derivative (FeTSPc) adsorbed on copper and gold electrodes have been observed in situ in 0.05 M H/sub 2/SO/sub 4/ solution. Results confirm the authors previous finding on the coordination of FePc to water molecules to solution. Evidence suggests that the iron phthalocyanines are probably oriented with their planes parallel to the electrode surface even in immersed electrodes. A decrease in intensity and broadening of some vibrational bands are observed on increasing cathodic polarization; these are attributed to a lifting of the degeneracy of the vibrational modes due to a change in symmetry of the adsorbed molecules brought about by polarization induced by the double-layer field. The effect of carbon on the Raman spectra is discussed. The iron phthalocyanines appear to be stable at potentials close to hydrogen evolution in the absence of oxygen. 18 references, 8 figures.

  4. In situ laser Raman spectra of iron phthalocyanine adsorbed on copper and gold electrodes

    SciTech Connect

    Melendres, C.A.; Rios, C.B.; Feng, X.; McMasters, R.

    1983-09-01

    Raman spectra of iron phthalocyanine (FePc) and its tetrasulfonated derivative (FeTSPc) adsorbed on copper and gold electrodes have been observed in situ in 0.05 M H/sub 2/SO/sub 4/ solution. Results confirm our previous finding on the coordination of FePc to water molecules to solution. Evidence suggests that the iron phthalocyanines are probably oriented with their planes parallel to the electrode surface even in immersed electrodes. A decrease in intensity and broadening of some vibrational bands are observed on increasing cathodic polarization; these are attributed to a lifting of the degeneracy of the vibrational modes due to a change in symmetry of the adsorbed molecules brought about by polarization induced by the double-layer field. The effect of carbon on the Raman spectra is discussed. The iron phthalocyanines appear to be stable at potentials close to hydrogen evolution in the absence of oxygen. 8 figures.

  5. Synthesis and optical limiting properties of new lanthanide bis- and tris-phthalocyanines

    NASA Astrophysics Data System (ADS)

    Sekhosana, Kutloano Edward; Manyeruke, Meloddy Hlatini; Nyokong, Tebello

    2016-10-01

    This manuscript reports on syntheses of new multi-decker phthalocyanines, namely: bis-{2,3,9,10,16,10,16,17,23,24-octa(4-tertbutylphenoxy) phthalocyaninato} cerium(III) (2), tris-{2,3,9,10,16,10,16,17,23,24-octa(4-tertbutylphenoxy) phthalocyaninato} dicerium(III) (4) and bis-{2,3,9,10,16,10,16,17,23,24-octa(4-tertbutylphenoxy) phthalocyaninato} gadolinium(III) (5). Complex 4 which is a tris phthalocyanine showed better nonlinear optical behavior in solution than 2 which is a bis phthalocyanine, both containing the same central metal, Ce. All the three molecules possess good optical limiting properties judged by the limiting threshold values which ranged from 0.04 to 0.09 J cm-2 with complex 5 embedded in thin films, showing the lowest value of 0.04 J cm-2. Furthermore, nonlinear optical processes responsible for reverse saturable absorption data are investigated.

  6. The substitution effect on the reorganization energy of metal free phthalocyanine

    NASA Astrophysics Data System (ADS)

    Lee, Choongkeun; Sohlberg, Karl

    2009-03-01

    Many discotic (disk like) materials such as phthalocyanine are of interest for use in organic electronic devices because of their high charge mobility. The mobility of various discotic materials has been studied using the Marcus formalism. In the Marcus formalism, charge mobility is depends on two parameters, reorganization energy and coupling matrix constant. Of these two parameters the reorganization energy has more influence on the charge hopping rate. A small change in reorganization energy leads to a large change of charge mobility. We have employed electronic structure methods to describe substitution effects on the reorganization energy of phthalocyanine. The substitutions on the external phenyl rings have almost no influence on reorganization energy, but the substitutions on the internal nitrogen in phthalocyanine have strong influence on reorganization energy. The detailed relation between reorganization energy and substitution will be presented.

  7. Zinc phthalocyanine-conjugated with bovine serum albumin mediated photodynamic therapy of human larynx carcinoma

    NASA Astrophysics Data System (ADS)

    Silva, E. P. O.; Santos, E. D.; Gonçalves, C. S.; Cardoso, M. A. G.; Soares, C. P.; Beltrame, M., Jr.

    2016-10-01

    Phthalocyanines, which are classified as second-generation photosensitizers, have advantageous photophysical properties, and extensive studies have demonstrated their potential applications in photodynamic therapy. The present work describes the preparation of a new zinc phthalocyanine conjugated to bovine serum albumin (compound 4a) and its photodynamic efficiency in human larynx-carcinoma cells (HEp-2 cells). The unconjugated precursor (compound 4) was also studied. Compounds 4 and 4a penetrated efficiently into the cell, exhibiting cytoplasmic localization, and showed no cytotoxicity in the dark. However, high photodynamic activities were observed in HEp-2 cells after treatments with 5 µM photosensitizers and 4.5 J cm-2 light. These conditions were sufficient to decrease the cell viability to 57.93% and 32.75% for compounds 4 and 4a, respectively. The present results demonstrated high photodynamic efficiency of zinc phthalocyanine conjugated with bovine serum albumin in destroying the larynx-carcinoma cells.

  8. Amphiphilic zinc phthalocyanine photosensitizers: synthesis, photophysicochemical properties and in vitro studies for photodynamic therapy.

    PubMed

    Çakır, Dilek; Göksel, Meltem; Çakır, Volkan; Durmuş, Mahmut; Biyiklioglu, Zekeriya; Kantekin, Halit

    2015-05-28

    Peripherally and non-peripherally tetra-substituted zinc(ii) phthalocyanines bearing 2-(2-{2-[3-(dimethylamino)phenoxy]ethoxy}ethoxy)ethoxy and 2-(2-{2-[3-(diethylamino)phenoxy]ethoxy}ethoxy)ethoxy groups (, , and ) were synthesized by cyclotetramerization of the corresponding phthalonitriles (, , and ). Their quaternized ionic derivatives (, , and ) were also synthesized by the reaction of them with methyl iodide. The novel compounds were characterized by using standard spectroscopic techniques such as FT-IR, (1)H NMR, (13)C NMR, UV-vis, mass and elemental analyses. The obtained quaternized phthalocyanines (, , and ) showed amphiphilic behaviour with excellent solubility in both organic and aqueous solutions, which makes them potential photosensitizers for use in photodynamic therapy (PDT) of cancer. The photophysical (fluorescence quantum yields and lifetimes) and photochemical (singlet oxygen and photodegradation quantum yields) properties of these novel phthalocyanines were studied in DMSO for both non-ionic and ionic quaternized derivatives. However, these properties were examined in both DMSO and phosphate buffer solution (PBS) for quaternized ionic phthalocyanines. The effects of the positions of substituents (peripheral or non-peripheral) and the quaternization of the nitrogen atoms on the substituents about their photophysical and photochemical properties were also compared in this study. The bovine serum albumin (BSA) binding behaviours of the studied quaternized ionic zinc(ii) phthalocyanines were also described in PBS solutions. The quaternized phthalocyanines (, , and ) successfully displayed light-dependent photodamage in HeLa and HuH-7 cancer cells in photodynamic therapy treatment. The photosensitivity and the intensity of damage were found directly related to the concentration of the photosensitizers.

  9. Sustainable proliferation of liposomes compatible with inner RNA replication.

    PubMed

    Tsuji, Gakushi; Fujii, Satoshi; Sunami, Takeshi; Yomo, Tetsuya

    2016-01-19

    Although challenging, the construction of a life-like compartment via a bottom-up approach can increase our understanding of life and protocells. The sustainable replication of genome information and the proliferation of phospholipid vesicles are requisites for reconstituting cell growth. However, although the replication of DNA or RNA has been developed in phospholipid vesicles, the sustainable proliferation of phospholipid vesicles has remained difficult to achieve. Here, we demonstrate the sustainable proliferation of liposomes that replicate RNA within them. Nutrients for RNA replication and membranes for liposome proliferation were combined by using a modified freeze-thaw technique. These liposomes showed fusion and fission compatible with RNA replication and distribution to daughter liposomes. The RNAs in daughter liposomes were repeatedly used as templates in the next RNA replication and were distributed to granddaughter liposomes. Liposome proliferation was achieved by 10 cycles of iterative culture operation. Therefore, we propose the use of culturable liposomes as an advanced protocell model with the implication that the concurrent supplement of both the membrane material and the nutrients of inner reactions might have enabled protocells to grow sustainably. PMID:26711996

  10. Heat-activated liposome targeting to streptavidin-coated surfaces.

    PubMed

    Jing, Yujia; Trefná, Hana Dobšíček; Persson, Mikael; Svedhem, Sofia

    2015-06-01

    There is a great need of improved anticancer drugs and corresponding drug carriers. In particular, liposomal drug carriers with heat-activated release and targeting functions are being developed for combined hyperthermia and chemotherapy treatments of tumors. The aim of this study is to demonstrate the heat-activation of liposome targeting to biotinylated surfaces, in model experiments where streptavidin is used as a pretargeting protein. The design of the heat-activated liposomes is based on liposomes assembled in an asymmetric structure and with a defined phase transition temperature. Asymmetry between the inside and the outside of the liposome membrane was generated through the enzymatic action of phospholipase D, where lipid head groups in the outer membrane leaflet, i.e. exposed to the enzyme, were hydrolyzed. The enzymatically treated and purified liposomes did not bind to streptavidin-modified surfaces. When activation heat was applied, starting from 22°C, binding of the liposomes occurred once the temperature approached 33±0.5°C. Moreover, it was observed that the asymmetric structure remained stable for at least 2 weeks. These results show the potential of asymmetric liposomes for the targeted binding to cell membranes in response to (external) temperature stimulus. By using pretargeting proteins, this approach can be further developed for personalized medicine, where tumor-specific antibodies can be selected for the conjugation of pretargeting agents.

  11. Sustainable proliferation of liposomes compatible with inner RNA replication

    PubMed Central

    Tsuji, Gakushi; Fujii, Satoshi; Sunami, Takeshi; Yomo, Tetsuya

    2016-01-01

    Although challenging, the construction of a life-like compartment via a bottom–up approach can increase our understanding of life and protocells. The sustainable replication of genome information and the proliferation of phospholipid vesicles are requisites for reconstituting cell growth. However, although the replication of DNA or RNA has been developed in phospholipid vesicles, the sustainable proliferation of phospholipid vesicles has remained difficult to achieve. Here, we demonstrate the sustainable proliferation of liposomes that replicate RNA within them. Nutrients for RNA replication and membranes for liposome proliferation were combined by using a modified freeze–thaw technique. These liposomes showed fusion and fission compatible with RNA replication and distribution to daughter liposomes. The RNAs in daughter liposomes were repeatedly used as templates in the next RNA replication and were distributed to granddaughter liposomes. Liposome proliferation was achieved by 10 cycles of iterative culture operation. Therefore, we propose the use of culturable liposomes as an advanced protocell model with the implication that the concurrent supplement of both the membrane material and the nutrients of inner reactions might have enabled protocells to grow sustainably. PMID:26711996

  12. Hydrogel Containing Nanoparticle-Stabilized Liposomes for Topical Antimicrobial Delivery

    PubMed Central

    2015-01-01

    Adsorbing small charged nanoparticles onto the outer surfaces of liposomes has become an effective strategy to stabilize liposomes against fusion prior to “seeing” target bacteria, yet allow them to fuse with the bacteria upon arrival at the infection sites. As a result, nanoparticle-stabilized liposomes have become an emerging drug delivery platform for treatment of various bacterial infections. To facilitate the translation of this platform for clinical tests and uses, herein we integrate nanoparticle-stabilized liposomes with hydrogel technology for more effective and sustained topical drug delivery. The hydrogel formulation not only preserves the structural integrity of the nanoparticle-stabilized liposomes, but also allows for controllable viscoeleasticity and tunable liposome release rate. Using Staphylococcus aureus bacteria as a model pathogen, we demonstrate that the hydrogel formulation can effectively release nanoparticle-stabilized liposomes to the bacterial culture, which subsequently fuse with bacterial membrane in a pH-dependent manner. When topically applied onto mouse skin, the hydrogel formulation does not generate any observable skin toxicity within a 7-day treatment. Collectively, the hydrogel containing nanoparticle-stabilized liposomes hold great promise for topical applications against various microbial infections. PMID:24483239

  13. Liposomes remain intact when complexed with polycationic brushes.

    PubMed

    Yaroslavov, Alexander A; Sybachin, Andrei V; Schrinner, Marc; Ballauff, Matthias; Tsarkova, Larisa; Kesselman, Ellina; Schmidt, Judith; Talmon, Yeshayahu; Menger, Fredric M

    2010-05-01

    Anionic liposomes adsorb onto the surface of spherical polymer particles bearing grafted linear cationic macromolecules. The size, shape, and encapsulation ability of the liposomes remain unchanged upon adsorption, thus providing immobilized self-organizing containers that have potential applications in the biomedical field. PMID:20387892

  14. Sustainable proliferation of liposomes compatible with inner RNA replication.

    PubMed

    Tsuji, Gakushi; Fujii, Satoshi; Sunami, Takeshi; Yomo, Tetsuya

    2016-01-19

    Although challenging, the construction of a life-like compartment via a bottom-up approach can increase our understanding of life and protocells. The sustainable replication of genome information and the proliferation of phospholipid vesicles are requisites for reconstituting cell growth. However, although the replication of DNA or RNA has been developed in phospholipid vesicles, the sustainable proliferation of phospholipid vesicles has remained difficult to achieve. Here, we demonstrate the sustainable proliferation of liposomes that replicate RNA within them. Nutrients for RNA replication and membranes for liposome proliferation were combined by using a modified freeze-thaw technique. These liposomes showed fusion and fission compatible with RNA replication and distribution to daughter liposomes. The RNAs in daughter liposomes were repeatedly used as templates in the next RNA replication and were distributed to granddaughter liposomes. Liposome proliferation was achieved by 10 cycles of iterative culture operation. Therefore, we propose the use of culturable liposomes as an advanced protocell model with the implication that the concurrent supplement of both the membrane material and the nutrients of inner reactions might have enabled protocells to grow sustainably.

  15. Theoretical modelling of exchange interactions in metal-phthalocyanines

    NASA Astrophysics Data System (ADS)

    Wu, Wei; Fisher, Andrew; Harrison, Nic; Serri, Michele; Wu, Zhenlin; Heutz, Sandrine; Jones, Tim; Aeppli, Gabriel

    2012-02-01

    The theoretical understanding of exchange interactions in organics provides a key foundation for quantum molecular magnetism. Recent SQUID magnetometry of a well know organic semiconductor, copper-phthalocyanine [1,2] (CuPc) shows that it forms quasi-one-dimensional spin chains. Green's function perturbation theory calculation [3] is used to find the dominant exchange mechanism. Hybrid density functional theory simulations [4] give a quantitative insight to exchange interactions and electronic structures. Both calculations are performed for different stacking and sliding angles for lithium-Pc, cobalt-Pc, chromium-Pc, and copper-Pc. The exchange interactions depend strongly on stacking angles, but weakly on sliding angles. Our results qualitatively agree with the experiments, and remarkably α-cobalt-Pc has a very large exchange above liquid-Nitrogen temperature. Our theoretical predictions on the exchange interactions can guide experimentalists to design novel organic semiconductors. [0pt] [1] S. Heutz, et. al., Adv. Mat., 19, 3618 (2007) [2] Hai Wang, et. al., ACS Nano, 4, 3921 (2010) [3] Wei Wu, et. al., Phys. Rev. B 77, 184403 (2008) [4] Wei Wu, et. al., Phys. Rev. B 84, 024427 (2011)

  16. Photodynamic therapy for experimental intraocular melanoma using chloroaluminum sulfonated phthalocyanine

    SciTech Connect

    Panagopoulos, J.A.; Svitra, P.P.; Puliafito, C.A.; Gragoudas, E.S.

    1989-06-01

    Chloroaluminum sulfonated phthalocyanine (CASPc), a novel photosensitizing dye, was evaluated for treatment of experimental intraocular melanoma in 33 rabbit eyes. An argon ion pumped dye laser, operating at an emission of 675 nm, was used in a nonthermal mode to irradiate iris tumors in rabbits 24 hours after they received in intravenous dye injection (23 eyes). The effects of laser irradiation alone and dye alone were examined in ten control eyes. A threshold tumoricidal dose was established for photodynamic therapy with CASPc and laser irradiation. Vascular occlusion was produced in a well-circumscribed area corresponding to the boundaries of laser irradiation after CASPc injection. Tumors successfully treated with CASPc and laser irradiation were arrested in growth and exhibited no viable tumor cells on histologic examination. Control tumors continued rapid growth, unaffected by dye or laser. Our data indicate that CASPc demonstrates a strong photosensitizing effect on both tumor and normal tissue. These results suggest that CASPc is a potential photosensitizing compound that may be useful in the treatment of choroidal melanoma.

  17. Synthesis of Phthalocyanines with a Pentafluorosulfanyl Substituent at Peripheral Positions.

    PubMed

    Iida, Norihito; Tanaka, Kenta; Tokunaga, Etsuko; Mori, Satoru; Saito, Norimichi; Shibata, Norio

    2015-12-01

    The pentafluorosulfanyl (SF5) group is more electronegative, lipophilic and sterically bulky relative to the well-explored trifluoromethyl (CF3) group. As such, the SF5 group could offer access to pharmaceuticals, agrochemicals and optoelectronic materials with novel properties. Here, the first synthesis of phthalocyanines (Pcs), a class of compounds used as dyes and with potential as photodynamic therapeutics, with a SF5 group directly attached on their peripheral positions is disclosed. The key for this work is the preparation of a series of SF5-containing phthalonitriles, which was beautifully regio-controlled by a stepwise cyanation via ortho-lithiation/iodination from commercially available pentafluorosulfanyl arenes. The macrocyclization of the SF5-containing phthalonitriles to SF5-substituted Pcs required harsh conditions with the exception of the synthesis of β-SF5-substituted Pc. The regiospecificity of the newly developed SF5-substituted Pcs observed by UV/Vis spectra and fluorescence quantum yields depend on the peripheral positon of the SF5 group. PMID:27308194

  18. Tuning the Structure and Photophysics of a Fluorous Phthalocyanine Platform.

    PubMed

    Farley, Christopher; Bhupathiraju, N V S Dinesh K; John, Bianca K; Drain, Charles Michael

    2016-09-29

    Phthalocyanines are an important class of industrial dyes with potential commercial applications ranging from photovoltaics to biomedical imaging and therapeutics. We previously demonstrated the versatility of the commercially available zinc(II) hexadecafluorophthalocyanine (ZnF16Pc) as a platform for rapidly developing functional materials for these applications and more. Because this core-platform approach to dye development is increasingly common, it is important to understand the photophysical and structural consequences of the substitution chemistry involved. We present a fundamental study of a series of ZnF16Pc derivatives in which the aromatic fluorine atoms are progressively substituted with thioalkanes. Clear spectroscopic trends are observed as the substituents change from electron-withdrawing to electron-releasing groups. Additionally, there is evidence for significant structural distortion of the normally planar heterocycle, with important ramifications for the photophysics. These results are also correlated to DFT calculations, which show that the orbital energies and symmetries are both important factors for explaining the excited-state dynamics. PMID:27552232

  19. Optical behaviour of copper phthalocyanine preparations for inkjet inks.

    PubMed

    Otáhalová, Lenka; Kaplanová, Marie; Gunde, Marta Klanjšek; Puchta, Miloš

    2011-06-01

    The present study investigates the preparation of the copper phthalocyanine pigment for inkjet printing inks. The pigment particle size distribution was measured with laser diffraction at different times of wet milling. Simultaneously, the absorbance spectra in a visible-near infrared spectral region of the corresponding diluted pigment dispersions were measured. At the beginning of the milling process, the particle size distribution is bimodal, showing the presence of aggregates and agglomerates. During the second hour of milling, the particle size distribution changes to unimodal due to the breaking of agglomerates, and the corresponding absorbance spectra change accordingly. Further milling diminishes the size of pigment aggregates up to the steady state value of around 130 nm, where also the absorbance in the corresponding spectra does not increase. A detailed analysis of intensity and position of the absorbance peak at 340 nm in dependence on the milling time and pigment concentration confirms the idea that an optical spectroscopy could be used for the assessment of optimal milling time required for the preparation of pigments with the maximum absorption ability.

  20. Adsorption Behavior of Nonplanar Phthalocyanines: Competition of Different Adsorption Conformations

    PubMed Central

    2016-01-01

    Using density functional theory augmented with state-of-the-art van der Waals corrections, we studied the geometric and electronic properties of nonplanar chlorogallium-phthalocyanine GaClPc molecules adsorbed on Cu(111). Comparing these results with published experimental data for adsorption heights, we found indications for breaking of the metal–halogen bond when the molecule is heated during or after the deposition process. Interestingly, the work-function change induced by this dissociated geometry is the same as that computed for an intact adsorbate layer in the “Cl-down” configuration, with both agreeing well with the experimental photoemission data. This is unexpected, as the chemical natures of the adsorbates and the adsorption distances are markedly different in the two cases. The observation is explained as a consequence of Fermi-level pinning due to fractional charge transfer at the interface. Our results show that rationalizing the adsorption configurations on the basis of electronic interface properties alone can be ambiguous and that additional insight from dispersion-corrected DFT simulations is desirable. PMID:27066160

  1. Spin tuning of electron-doped metal-phthalocyanine layers.

    PubMed

    Stepanow, Sebastian; Lodi Rizzini, Alberto; Krull, Cornelius; Kavich, Jerald; Cezar, Julio C; Yakhou-Harris, Flora; Sheverdyaeva, Polina M; Moras, Paolo; Carbone, Carlo; Ceballos, Gustavo; Mugarza, Aitor; Gambardella, Pietro

    2014-04-01

    The spin state of organic-based magnets at interfaces is to a great extent determined by the organic environment and the nature of the spin-carrying metal center, which is further subject to modifications by the adsorbate-substrate coupling. Direct chemical doping offers an additional route for tailoring the electronic and magnetic characteristics of molecular magnets. Here we present a systematic investigation of the effects of alkali metal doping on the charge state and crystal field of 3d metal ions in Cu, Ni, Fe, and Mn phthalocyanine (Pc) monolayers adsorbed on Ag. Combined X-ray absorption spectroscopy and ligand field multiplet calculations show that Cu(II), Ni(II), and Fe(II) ions reduce to Cu(I), Ni(I), and Fe(I) upon alkali metal adsorption, whereas Mn maintains its formal oxidation state. The strength of the crystal field at the Ni, Fe, and Mn sites is strongly reduced upon doping. The combined effect of these changes is that the magnetic moment of high- and low-spin ions such as Cu and Ni can be entirely turned off or on, respectively, whereas the magnetic configuration of MnPc can be changed from intermediate (3/2) to high (5/2) spin. In the case of FePc a 10-fold increase of the orbital magnetic moment accompanies charge transfer and a transition to a high-spin state.

  2. Organic semiconductor nickel phthalocyanine-based photocapacitive and photoresistive detector

    NASA Astrophysics Data System (ADS)

    Shah, Mutabar; Karimov, Kh S.; Sayyad, M. H.

    2010-07-01

    In this study, the photosensitive organic semiconductor nickel phthalocyanine (NiPc) is investigated as a photocapacitive and photoresistive detector. NiPc thin film is grown by vacuum thermal evaporation on an indium tin oxide (ITO)-coated glass substrate. Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is deposited as a top electrode by drop-casting to fabricate the ITO/NiPc/PEDOT:PSS light detector. It has been observed that under the unmodulated filament lamp illumination of up to 9720 lux the capacitance of the detectors increased up to 21, 18 and 4% at a frequency of measuring voltage of 120 Hz, 1 kHz and 10 kHz, respectively, under dark conditions. The change in resistance with the variation in the intensity of light is also investigated. The capacitance and resistance of the light detector decrease with an increase in the frequency. It is assumed that the photocapacitive and photoresistive response of the detector is associated with polarization occurring due to the transfer of photo-generated electrons and holes. The calculated results are in reasonable agreement with the experimental results.

  3. Electrochemical and spectroelectrochemical properties of thiadiazole substituted metallo-phthalocyanines.

    PubMed

    Demirbaş, Ümit; Akyüz, Duygu; Barut, Burak; Bayrak, Rıza; Koca, Atıf; Kantekin, Halit

    2016-01-15

    4-Thiadiazole substituted phthalonitrile and peripherally tetra-substituted phthalocyanine Cu(II), Fe(II) and Ti(IV)O complexes have been synthesized for the first time. Electrochemical properties of these complexes were determined with voltammetric and in situ spectroelectrochemical measurements. CuPc has redox inactive Cu(2+) center, therefore it gave three Pc based reduction and two Pc based oxidation processes. TiOPc and FePc complexes gave metal based redox processes in addition to Pc based redox reactions due to the redox activity of Ti(4+)O and Fe(2+) metal centers. Although FePc also gave three reduction and two oxidation reactions, peak potentials of these processes are different than those of CuPc due to the different assignments of the redox reactions. TiOPc went to five reduction and one oxidation reactions. Assignments of the redox processes were carried out with in situ spectroelectrochemical measurements. Spectra and color of the electrogenerated redox species of the complexes were also determined with in situ spectroelectrochemical and in situ electrocolorimetric measurements. Distinct color differences between the electrogenerated redox species were observed, which indicated their possible electrochromic usages.

  4. STM Studies of Iron Phthalocyanine on Fe(110) Films

    NASA Astrophysics Data System (ADS)

    Sandin, Andreas; Dougherty, Dan; Rowe, J. E. (Jack)

    2011-03-01

    We have observed molecular-scale-resolution arrays of Iron Phthalocyanine (FePc) molecules which we adsorbed at room temperature on thin (~ 5-10 ML) films of Fe(110). These molecular layers were grown in a UHV Omicron/AFM/STM/ multi-probe system at NC State in the Physics Department at pressures of ~ 10-10 torr. Our results indicate a strong inter-molecular interaction that produces well-ordered films at monolayer coverage. For lower coverage (~ 0.2 -- 0.6 ML) the FePc-Fe substrate interaction strongly dominates and the STM image morphology has only small clusters of 2-6 molecules. Our data clearly shown that the FePc molecules are lying flat on the surface in the ordered ~ 1 ML samples since we see evidence of the carbon-ring ligands in some images. We discuss the possibility of spin-dependent effects between the molecular Fe and the substrate Fe as an example of potential molecular-modified spin-based devices. Initial STM-spectroscopy including both I vs. V and Z vs. V results are consistent with our structural observations. Supported in part by the NSF Chemical Centers for Innovation program (Grant CHE-0943975).

  5. Direct insertion of metal ions into tetrasulfonated phthalocyanine

    SciTech Connect

    Linkous, C.A.; Shea, C.E.; Jaber, M.R.A. )

    1989-07-01

    A series of metal salts were reacted with aqueous solutions of the tetrasulfonated free base phthalocyanine (H{sub 2}TsPc) in an attempt to prepare the corresponding metal TsPc derivative by direct insertion instead of the usual template reaction in a urea melt. Spectrophotometric analysis showed that Ni{sup 2+}, Cu{sup 2+}, Zn{sup 2+}, Co{sup 2+}, Fe{sup 2+}, Mn{sup 2+}, Pd{sup 2+}, Cd{sup 2+}, and Sn{sup 2+} could be successfully inserted; higher oxidation states as well as Pb{sup 2+} caused precipitation. Reducing species such as Cr{sup 2+} and V{sup 2+} reduced H{sub 2}TsPc but did not insert; Sn{sup 2+} inserted with formation of an air-sensitive intermediate species. Mg{sup 2+}, VO{sup 2+}, Pt{sup 2+}, and Hg{sup 2+} were unreactive. It is recommended that insertion may be the preferable method for synthesis of the MTsPc's listed above when air sensitivity, reaction time, and microscale are important issues in an overall synthetic scheme. 24 refs., 4 figs.

  6. Mixed configuration ground state in iron(II) phthalocyanine

    NASA Astrophysics Data System (ADS)

    Fernández-Rodríguez, Javier; Toby, Brian; van Veenendaal, Michel

    2015-06-01

    We calculate the angular dependence of the x-ray linear and circular dichroism at the L2 ,3 edges of α -Fe(II) Phthalocyanine (FePc) thin films using a ligand-field model with full configuration interaction. We find the best agreement with the experimental spectra for a mixed ground state of 3Eg(a1g 2eg3b2g 1) and 3B2 g(a1g 1eg4b2g 1) with the two configurations coupled by the spin-orbit interaction. The 3Eg(b ) and 3B2 g states have easy-axis and easy-plane anisotropies, respectively. Our model accounts for an easy-plane magnetic anisotropy and the measured magnitudes of the in-plane orbital and spin moments. The proximity in energy of the two configurations allows a switching of the magnetic anisotropy from easy plane to easy axis with a small change in the crystal field, as recently observed for FePc adsorbed on an oxidized Cu surface. We also discuss the possibility of a quintet ground state (5A1 g is 250 meV above the ground state) with planar anisotropy by manipulation of the Fe-C bond length by depositing the complex on a substrate that is subjected to a mechanical strain.

  7. Resonance Raman spectra of. cap alpha. -copper phthalocyanine

    SciTech Connect

    Bovill, A.J.; McConnell, A.A.; Nimmo, J.A.; Smith, W.E.

    1986-02-13

    Raman spectra of ..cap alpha..-copper phthalocyanine (..cap alpha..-CuPc) were recorded at room temperature and at 10 K with excitation wavelengths between 457 and 714 nm. Resonance enhancement was greatest for modes for which the largest displacements were on either the inner five-membered ring of the isoindole groups or the inner macrocycle and consequently assignment of the bands to modes of the entire molecule was possible by comparison with nickel octaethylporphyrin. Four out of five bands resonant in the Q band region and preresonant near the B band absorption region are totally symmetric modes. B band preresonance occurs more strongly with high-frequency modes. At low temperatures, multimode interactions are reduced and profiles were obtained which can be compared with solution profiles of porphyrins. Both Q/sub x/ and Q/sub y/ 0-0 scattering can be identified and a helper mode is evident. A term enhancement predominates, with B/sub 1g/ and B/sub 2g/ modes enhanced because of a Jahn-Teller distortion of the excited state. The resonance studies, together with electronic absorption spectra and published theoretical studies, confirm that the Q band in ..cap alpha..-CuPc is largely due to an allowed ..pi..-..pi..* transition associated mainly with the macrocycle and inner five-membered rings of the isoindole groups. 25 references, 5 figures, 2 tables.

  8. Commensurism at electronically weakly interacting phthalocyanine/PTCDA heterointerfaces

    NASA Astrophysics Data System (ADS)

    Gruenewald, Marco; Sauer, Christoph; Peuker, Julia; Meissner, Matthias; Sojka, Falko; Schöll, Achim; Reinert, Friedrich; Forker, Roman; Fritz, Torsten

    2015-04-01

    Interfaces in multilayered electronic devices are of paramount importance, especially for layer thicknesses in the nanometer range. Among the interfacial processes are charge injection or extraction and excitonic dissociation, the latter being particularly relevant if molecular components are involved. Highly ordered superstructures are preferable to prevent undesired losses of charge carriers and/or excitons. Epitaxial organic-inorganic systems have already received eminent attention, but only few studies have dealt with organic-organic heterointerfaces so far. Here, we focus on the adsorption of metal-phthalocyanines (MePc, Me = Sn or Cu) on 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) in the form of stacked monolayers (ML) on Ag(111). Using scanning tunneling microscopy and low-energy electron diffraction we reveal an initial nonordered growth for dilute SnPc submonolayers and consecutively three condensed phases at coverages ranging up to 1 ML —each possessing a distinct commensurate registry with the underlying PTCDA. By applying in situ optical differential reflectance spectroscopy and photoelectron spectroscopy we find that neither the SnPc nor the CuPc phases exhibit significant electronic or optical coupling with the PTCDA interlayer. Therefore, our results demonstrate that commensurism does not necessarily imply chemisorption, as stated previously in the literature, but that physisorption may be accompanied by commensurate superstructures.

  9. Electrochemical and spectroelectrochemical properties of thiadiazole substituted metallo-phthalocyanines

    NASA Astrophysics Data System (ADS)

    Demirbaş, Ümit; Akyüz, Duygu; Barut, Burak; Bayrak, Rıza; Koca, Atıf; Kantekin, Halit

    2016-01-01

    4-Thiadiazole substituted phthalonitrile and peripherally tetra-substituted phthalocyanine Cu(II), Fe(II) and Ti(IV)O complexes have been synthesized for the first time. Electrochemical properties of these complexes were determined with voltammetric and in situ spectroelectrochemical measurements. CuPc has redox inactive Cu2 + center, therefore it gave three Pc based reduction and two Pc based oxidation processes. TiOPc and FePc complexes gave metal based redox processes in addition to Pc based redox reactions due to the redox activity of Ti4 +O and Fe2 + metal centers. Although FePc also gave three reduction and two oxidation reactions, peak potentials of these processes are different than those of CuPc due to the different assignments of the redox reactions. TiOPc went to five reduction and one oxidation reactions. Assignments of the redox processes were carried out with in situ spectroelectrochemical measurements. Spectra and color of the electrogenerated redox species of the complexes were also determined with in situ spectroelectrochemical and in situ electrocolorimetric measurements. Distinct color differences between the electrogenerated redox species were observed, which indicated their possible electrochromic usages.

  10. New approaches to photodynamic therapy of tumors with Al phthalocyanine

    NASA Astrophysics Data System (ADS)

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

    1999-12-01

    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.

  11. Preclinical evaluation of zinc phthalocyanine tetrasulfonate-based PDT

    NASA Astrophysics Data System (ADS)

    Borgatti-Jeffreys, Antonella; Hooser, Stephen B.; Miller, Margaret A.; Thomas, Rose M.; deGortari, Amalia; Lucroy, Michael D.

    2005-04-01

    Photodynamic therapy (PDT) involves the light activation of a drug within a tumor causing selective tumor cell death. Unfortunately, some photosensitizing drugs have been associated with adverse reactions in veterinary patients. Zinc phthalocyanine tetrasulfonate (ZnPcS4) is a promising second-generation photosensitizer for use in veterinary medicine, however, it cannot be applied clinically until safety and efficacy data are available. ZnPcS4 was given to Swiss Webster mice to assess acute toxicity. Doses >100 mg/kg were associated with acute toxicity and mortality, and doses >100 mg/kg resulted in renal tubular nephrosis, suggesting that the minimum toxic dose is approximately 100 mg/kg. Based on these data, a Phase I clinical trial of ZnPcS4-based PDT in tumor-bearing dogs is underway, with ZnPcS4 doses up to 2 mg/kg producing no apparent toxicity. Tumor response has been observed after ZnPcS4-based PDT using doses as low as 0.25 mg/kg, suggesting that conventional phase I clinical trials may not be appropriate for PDT protocols.

  12. Anisotropic exciton relaxation in nanostructured metal (Zn and F(16)Zn)-phthalocyanine.

    PubMed

    Ahn, Hyeyoung; Liou, Wei-Hyun; Chen, Huang-Ming Philip; Hsu, Chia-Hung

    2015-02-01

    We report ultrafast excited state dynamics of zinc phthalocyanine and zinc hexadecafluoro phthalocyanine thin films which have nanorod-like structures. Excitons in the singlet states undergo multi-exponential relaxation processes to the ground state and the singlet lifetime within a few tens of picoseconds is attributed to the diffusion-limited exciton annihilation process. Diffusive migration of the singlet excitons shows the anisotropic lifetimes depending on the polarization of probe beam. Similar anisotropy is observed in the X-ray diffraction data which exhibits long-range alignment of molecular columns along the long axis of nanorod, whereas disordered arrangement in lateral direction to the axis of nanorod. PMID:25836181

  13. Influence of film thickness and air exposure on the transport gap of manganese phthalocyanine

    SciTech Connect

    Haidu, F.; Fechner, A.; Salvan, G.; Gordan, O. D.; Fronk, M.; Zahn, D. R. T.; Lehmann, D.; Mahns, B.; Knupfer, M.

    2013-06-15

    The interface formation between manganese phthalocyanine (MnPc) and cobalt was investigated combining ultraviolet photoelectron spectroscopy and inverse photoelectron spectroscopy. The transport band gap of the MnPc increases with the film thickness up to a value of (1.2 {+-} 0.3) eV while the optical band gap as determined from spectroscopic ellipsometry amounts to 0.5 eV. The gap values are smaller compared to other phthalocyanines due to metallic Mn 3d states close to the Fermi level. The transport band gap was found to open upon air exposure as a result of the disappearance of the occupied 3d electronic states.

  14. Application of nanophotosensitizers (aluminum phthalocyanine nanoparticles) for early diagnosis and prevention of inflammatory diseases

    NASA Astrophysics Data System (ADS)

    Kuznetsova, J. O.; Makarov, V. I.

    2016-08-01

    This paper deals with a possibility of new types of photosensitizers application - Aluminum Phthalocyanine nanoparticles (nAlPc) in clinical practice for diagnosis, prevention and therapy of inflammatory diseases in dentistry and traumatology. It was detected that the aluminum phthalocyanine (AlPc) fluoresces in the nanoparticle form in the presence of pathologic microflora or inflammation process. It will make possible to detect the local accumulation of pathological microflora on the enamel surface and also for diagnostics and treatment of inflammatory diseases. Experimental studies of interaction of NP-AlPc with tooth enamel and with biological joint tissue at arthrosis are presented.

  15. Highly aspherical silica nanoshells by templating tubular liposomes

    PubMed Central

    Tan, Grace; Xu, Peng; He, Jibao; Lawson, Louise; McPherson, Gary L.

    2010-01-01

    A dual-lipid liposome system consisting of a phospholipid and a skin ceramide extruded though a 100 nm membrane yields novel tubular and helical liposomes. These liposomes were used as templates to generate highly aspherical silica nanocapsules with length to diameter aspect ratios exceeding 10. Many of these nanocapsules have the morphology of a bulbous end attached to a long tip, mimicking microneedles attached to a reservoir. The fidelity of helical liposomes is transcribed to the silicas and the long tips indicate helically entwined left-handed silica structures. The silica coating is expected to protect and stabilize the internal contents of the liposomes, as well as enable surface functionalization for applications in drug or targeted delivery. PMID:20352059

  16. Ultrasound triggered drug delivery with liposomal nested microbubbles.

    PubMed

    Wallace, N; Wrenn, S P

    2015-12-01

    When ultrasound contrast agent microbubbles are nested within a liposome, damage to the liposome membrane caused by both stable and inertial cavitation of the microbubble allows for release of the aqueous core of the liposome. Triggered release was not accomplished unless microbubbles were present within the liposome. Leakage was tested using fluorescence assays developed specifically for this drug delivery vehicle and qualitative measurements using an optical microscope. These studies were done using a 1 MHz focused ultrasound transducer while varying parameters including peak negative ultrasound pressure, average liposome diameter, and microbubble concentration. Two regimes exist for membrane disruption caused by cavitating microbubbles. A faster release rate, as well as permanent membrane damage are seen for samples exposed to high pressure (2.1-3.7 MPa). A slower release rate and dilation/temporary poration are characteristic of stable cavitation for low pressure studies (0.54-1.7 MPa).

  17. Multimodal targeted high relaxivity thermosensitive liposome for in vivo imaging

    NASA Astrophysics Data System (ADS)

    Kuijten, Maayke M. P.; Hannah Degeling, M.; Chen, John W.; Wojtkiewicz, Gregory; Waterman, Peter; Weissleder, Ralph; Azzi, Jamil; Nicolay, Klaas; Tannous, Bakhos A.

    2015-11-01

    Liposomes are spherical, self-closed structures formed by lipid bilayers that can encapsulate drugs and/or imaging agents in their hydrophilic core or within their membrane moiety, making them suitable delivery vehicles. We have synthesized a new liposome containing gadolinium-DOTA lipid bilayer, as a targeting multimodal molecular imaging agent for magnetic resonance and optical imaging. We showed that this liposome has a much higher molar relaxivities r1 and r2 compared to a more conventional liposome containing gadolinium-DTPA-BSA lipid. By incorporating both gadolinium and rhodamine in the lipid bilayer as well as biotin on its surface, we used this agent for multimodal imaging and targeting of tumors through the strong biotin-streptavidin interaction. Since this new liposome is thermosensitive, it can be used for ultrasound-mediated drug delivery at specific sites, such as tumors, and can be guided by magnetic resonance imaging.

  18. Use of Adaptive Focused Acoustics™ ultrasound in controlling liposome formation.

    PubMed

    Shen, Katherine C; Kakumanu, Srikanth; Beckett, Carl D; Laugharn, James A

    2015-11-01

    Many techniques for producing large unilamellar vesicles (LUVs) or small unilamellar vesicles (SUVs) have drawbacks, including exposure of sensitive biological materials to harsh organic solvents or high temperatures. Here we describe the use of controlled focused ultrasound, Adaptive Focused Acoustics™ (AFA), to make LUV or SUV at low temperature without organic solvents and at a consistent, chosen size. We studied the effects of peak incident power (PIP), cycles per burst (CPB), duty factor (DF), temperature, and lipid composition (natural or synthetic), on liposome size distribution. We found that an increase in PIP, DF, CPB, or temperature decreased liposome size. When processed under the same conditions as the natural lipid composition [Phospholipon 90 G], the synthetic lipid composition [HSPC, DSPE-PEG-2000, Chol] generally produced larger liposomes, although extending processing time reduced liposomes to similar size. In combination with AFA, these trends can help pinpoint parameter values that achieve a desired liposome size distribution.

  19. Enhanced antitumor effect of novel dual-targeted paclitaxel liposomes

    NASA Astrophysics Data System (ADS)

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

    2010-10-01

    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.

  20. Multimodal targeted high relaxivity thermosensitive liposome for in vivo imaging

    PubMed Central

    Kuijten, Maayke M. P.; Hannah Degeling, M.; Chen, John W.; Wojtkiewicz, Gregory; Waterman, Peter; Weissleder, Ralph; Azzi, Jamil; Nicolay, Klaas; Tannous, Bakhos A.

    2015-01-01

    Liposomes are spherical, self-closed structures formed by lipid bilayers that can encapsulate drugs and/or imaging agents in their hydrophilic core or within their membrane moiety, making them suitable delivery vehicles. We have synthesized a new liposome containing gadolinium-DOTA lipid bilayer, as a targeting multimodal molecular imaging agent for magnetic resonance and optical imaging. We showed that this liposome has a much higher molar relaxivities r1 and r2 compared to a more conventional liposome containing gadolinium-DTPA-BSA lipid. By incorporating both gadolinium and rhodamine in the lipid bilayer as well as biotin on its surface, we used this agent for multimodal imaging and targeting of tumors through the strong biotin-streptavidin interaction. Since this new liposome is thermosensitive, it can be used for ultrasound-mediated drug delivery at specific sites, such as tumors, and can be guided by magnetic resonance imaging. PMID:26610702

  1. Recent Developments of Liposomes as Nanocarriers for Theranostic Applications

    PubMed Central

    Xing, Hang; Hwang, Kevin; Lu, Yi

    2016-01-01

    Liposomes are nanocarriers comprised of lipid bilayers encapsulating an aqueous core. The ability of liposomes to encapsulate a wide variety of diagnostic and therapeutic agents has led to significant interest in utilizing liposomes as nanocarriers for theranostic applications. In this review, we highlight recent progress in developing liposomes as nanocarriers for a) diagnostic applications to detect proteins, DNA, and small molecule targets using fluorescence, magnetic resonance, ultrasound, and nuclear imaging; b) therapeutic applications based on small molecule-based therapy, gene therapy and immunotherapy; and c) theranostic applications for simultaneous detection and treatment of heavy metal toxicity and cancers. In addition, we summarize recent studies towards understanding of interactions between liposomes and biological components. Finally, perspectives on future directions in advancing the field for clinical translations are also discussed. PMID:27375783

  2. Electromagnetic field triggered drug and chemical delivery via liposomes

    DOEpatents

    Liburdy, Robert P.

    1993-01-01

    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 said chemical agent from the liposomes at a temperature of between about +10 and 65.degree. C. The invention further relates to the use of said 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.

  3. Shrinkage of pegylated and non-pegylated liposomes in serum

    PubMed Central

    Wolfram, Joy; Suri, Krishna; Yang, Yong; Shen, Jianliang; Celia, Christian; Fresta, Massimo; Zhao, Yuliang; Shen, Haifa; Ferrari, Mauro

    2013-01-01

    An essential requisite for the design of nanodelivery systems is the ability to characterize the size, homogeneity and zeta potential of nanoparticles. Such properties can be tailored in order to create the most efficient drug delivery platforms. An important question is whether these characteristics change upon systemic injection. Here, we have studied the behavior of phosphatidylcholine/cholesterol liposomes exposed to serum proteins. The results reveal a serum-induced reduction in the size and homogeneity of both pegylated and non-pegylated liposomes, implicating the possible role of osmotic forces. In addition, changes to zeta-potential were observed upon exposing liposomes to serum. The liposomes with polyethylene glycol expressed different characteristics than their non-polymeric counterparts, suggesting the potential formation of a denser protein corona around the non-pegylated liposomes. PMID:24216620

  4. Electromagnetic field triggered drug and chemical delivery via liposomes

    DOEpatents

    Liburdy, R.P.

    1993-03-02

    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.

  5. Microfabrication of three-dimensional filters for liposome extrusion

    NASA Astrophysics Data System (ADS)

    Baldacchini, Tommaso; Nuñez, Vicente; LaFratta, Christopher N.; Grech, Joseph S.; Vullev, Valentine I.; Zadoyan, Ruben

    2015-03-01

    Liposomes play a relevant role in the biomedical field of drug delivery. The ability of these lipid vesicles to encapsulate and transport a variety of bioactive molecules has fostered their use in several therapeutic applications, from cancer treatments to the administration of drugs with antiviral activities. Size and uniformity are key parameters to take into consideration when preparing liposomes; these factors greatly influence their effectiveness in both in vitro and in vivo experiments. A popular technique employed to achieve the optimal liposome dimension (around 100 nm in diameter) and uniform size distribution is repetitive extrusion through a polycarbonate filter. We investigated two femtosecond laser direct writing techniques for the fabrication of three-dimensional filters within a microfluidics chip for liposomes extrusion. The miniaturization of the extrusion process in a microfluidic system is the first step toward a complete solution for lab-on-a-chip preparation of liposomes from vesicles self-assembly to optical characterization.

  6. Preparation and characterization of clove essential oil-loaded liposomes.

    PubMed

    Sebaaly, Carine; Jraij, Alia; Fessi, Hatem; Charcosset, Catherine; Greige-Gerges, Hélène

    2015-07-01

    In this study, suitable formulations of natural soybean phospholipid vesicles were developed to improve the stability of clove essential oil and its main component, eugenol. Using an ethanol injection method, saturated (Phospholipon 80H, Phospholipon 90H) and unsaturated soybean (Lipoid S100) phospholipids, in combination with cholesterol, were used to prepare liposomes at various eugenol and clove essential oil concentrations. Liposomal batches were characterized and compared for their size, polydispersity index, Zeta potential, loading rate, encapsulation efficiency and morphology. The liposomes were tested for their stability after storing them for 2 months at 4°C by monitoring changes in their mean size, polydispersity index and encapsulation efficiency (EE) values. It was found that liposomes exhibited nanometric oligolamellar and spherical shaped vesicles and protected eugenol from degradation induced by UV exposure; they also maintained the DPPH-scavenging activity of free eugenol. Liposomes constitute a suitable system for encapsulation of volatile unstable essential oil constituents. PMID:25704683

  7. Current Trends in Development of Liposomes for Targeting Bacterial Biofilms

    PubMed Central

    Rukavina, Zora; Vanić, Željka

    2016-01-01

    Biofilm targeting represents a great challenge for effective antimicrobial therapy. Increased biofilm resistance, even with the elevated concentrations of very potent antimicrobial agents, often leads to failed therapeutic outcome. Application of biocompatible nanomicrobials, particularly liposomally-associated nanomicrobials, presents a promising approach for improved drug delivery to bacterial cells and biofilms. Versatile manipulations of liposomal physicochemical properties, such as the bilayer composition, membrane fluidity, size, surface charge and coating, enable development of liposomes with desired pharmacokinetic and pharmacodynamic profiles. This review attempts to provide an unbiased overview of investigations of liposomes destined to treat bacterial biofilms. Different strategies including the recent advancements in liposomal design aiming at eradication of existing biofilms and prevention of biofilm formation, as well as respective limitations, are discussed in more details. PMID:27231933

  8. Recent Developments in Liposome-Based Veterinary Therapeutics

    PubMed Central

    2013-01-01

    Recent advances in nanomedicine have been studied in the veterinary field and have found a wide variety of applications. The past decade has witnessed a massive surge of research interest in liposomes for delivery of therapeutic substances in animals. Liposomes are nanosized phospholipid vesicles that can serve as delivery platforms for a wide range of substances. Liposomes are easily formulated, highly modifiable, and easily administered delivery platforms. They are biodegradable and nontoxic and have long in vivo circulation time. This review focuses on recent and ongoing research that may have relevance for veterinary medicine. By examining the recent developments in liposome-based therapeutics in animal cancers, vaccines, and analgesia, this review depicts the current significance and future directions of liposome-based delivery in veterinary medicine. PMID:24222862

  9. Mechanical properties of a giant liposome studied using optical tweezers

    NASA Astrophysics Data System (ADS)

    Shitamichi, Yoko; Ichikawa, Masatoshi; Kimura, Yasuyuki

    2009-09-01

    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 σ and the bending rigidity κ of the lipid membrane are obtained from the measured force-extension curve. In a one-phase liposome, it was found that σ increases as the charged component increases but κ 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.

  10. Ligand-targeted liposome design: challenges and fundamental considerations.

    PubMed

    Noble, Gavin T; Stefanick, Jared F; Ashley, Jonathan D; Kiziltepe, Tanyel; Bilgicer, Basar

    2014-01-01

    Nanomedicine, particularly liposomal drug delivery, has expanded considerably over the past few decades, and several liposomal drugs are already providing improved clinical outcomes. Liposomes have now progressed beyond simple, inert drug carriers and can be designed to be highly responsive in vivo, with active targeting, increased stealth, and controlled drug-release properties. Ligand-targeted liposomes (LTLs) have the potential to revolutionize the treatment of cancer. However, these highly engineered liposomes generate new problems, such as accelerated clearance from circulation, compromised targeting owing to non-specific serum protein binding, and hindered tumor penetration. This article highlights recent challenges facing LTL strategies and describes the advanced design elements used to circumvent them. PMID:24210498

  11. Cell penetrating peptide conjugated liposomes as transdermal delivery system of Polygonum aviculare L. extract.

    PubMed

    Kwon, Soon Sik; Kim, Sun Young; Kong, Bong Ju; Kim, Kyeong Jin; Noh, Geun Young; Im, Na Ri; Lim, Ji Won; Ha, Ji Hoon; Kim, Junoh; Park, Soo Nam

    2015-04-10

    In this study, Polygonum aviculare L. extract, which has superior antioxidative and cellular membrane protective activity, was loaded onto cell penetrating peptide (CPP) conjugated liposomes to enhance transdermal delivery. The physical characteristics of typical liposomes and CPP-conjugated liposomes containing P. aviculare extract were evaluated. The particle sizes of both liposomes were approximately 150 nm. Whereas the zeta potential of typical liposomes was -45 mV, that of CPP-conjugated liposomes was +42 mV. The loading efficiency of P. aviculare extract in both liposomes was calculated to be about 83%. Fluorescent-labeled liposomes were prepared to evaluate cellular uptake and skin permeation efficiency. Using flow cytometry, we found that CPP-conjugated liposomes improved cellular uptake of the fluorescent dye as compared with the typical liposomes. In addition, the skin permeation of CPP-conjugated liposomes was proved higher than that of typical liposomes by confocal laser scanning microscopy studies and Franz diffusion cell experiments. The improved cellular uptake and skin permeation of the CPP-conjugated liposomes were due to the cationic arginine-rich peptide. In vivo studies also determined that the CPP-conjugated liposomes were more effective in depigmentation and anti-wrinkle studies than typical liposomes. These results indicate that the CPP-conjugated liposomes could be effective for transdermal drug delivery of antioxidant and anti-aging therapeutics.

  12. Image-Guided Predictions of Liposome Transport in Solid Tumours

    NASA Astrophysics Data System (ADS)

    Stapleton, Shawn

    Due to the ability to preferentially accumulate and deliver drug payloads to solid tumours, liposomes have emerged as an exciting therapeutic strategy for cancer therapy. Unfortunately, the initial excitement was dampened by limited clinical results, where only negligible increases in patient survival following liposome therapy have been observed. What are the reasons for the limited clinical efficacy? Is the nanoparticle formulation optimal? Is the enhanced permeability and retention effect overstated? What are the barriers limiting the delivery of drugs to cancer cells? What is the optimal dosing and treatment schedule? Addressing these questions requires developing quantitative tools to understand the behaviour of liposomes in vivo, such as pharmacokinetics, biodistribution, intra-tumoural accumulation, and drug release. Central to each of these questions is the concept of transport - the collection of biophysical processes responsible for the delivery of molecules to tissues. Understanding transport means understanding the crucial links between the spatio-temporal accumulation of liposomes, the physicochemical properties of liposomes, and properties of the tumour microenvironment. In this thesis, a biophysical mathematical transport model is developed that when used in combination with non-invasive imaging methods can predict liposome transport in solid tumours. The mathematical transport framework is validated in its ability to predict the bulk and intra-tumoural accumulation of liposomes based on biophysical transport properties of solid tumours. Furthermore, novel imaging methods are developed and used to elucidate the crucial links between transport barriers and spatial heterogeneity in liposome accumulation. Finally, methods are presented to integrate quantitative imaging and mathematical modelling such that an accurate prediction of liposome transport in solid tumours is possible. In summary, this thesis presents and validates an image-guided mathematical

  13. Light induced cytosolic drug delivery from liposomes with gold nanoparticles.

    PubMed

    Lajunen, Tatu; Viitala, Lauri; Kontturi, Leena-Stiina; Laaksonen, Timo; Liang, Huamin; Vuorimaa-Laukkanen, Elina; Viitala, Tapani; Le Guével, Xavier; Yliperttula, Marjo; Murtomäki, Lasse; Urtti, Arto

    2015-04-10

    Externally triggered drug release at defined targets allows site- and time-controlled drug treatment regimens. We have developed liposomal drug carriers with encapsulated gold nanoparticles for triggered drug release. Light energy is converted to heat in the gold nanoparticles and released to the lipid bilayers. Localized temperature increase renders liposomal bilayers to be leaky and triggers drug release. The aim of this study was to develop a drug releasing system capable of releasing its cargo to cell cytosol upon triggering with visible and near infrared light signals. The liposomes were formulated using either heat-sensitive or heat- and pH-sensitive lipid compositions with star or rod shaped gold nanoparticles. Encapsulated fluorescent probe, calcein, was released from the liposomes after exposure to the light. In addition, the pH-sensitive formulations showed a faster drug release in acidic conditions than in neutral conditions. The liposomes were internalized into human retinal pigment epithelial cells (ARPE-19) and human umbilical vein endothelial cells (HUVECs) and did not show any cellular toxicity. The light induced cytosolic delivery of calcein from the gold nanoparticle containing liposomes was shown, whereas no cytosolic release was seen without light induction or without gold nanoparticles in the liposomes. The light activated liposome formulations showed a controlled content release to the cellular cytosol at a specific location and time. Triggering with visual and near infrared light allows good tissue penetration and safety, and the pH-sensitive liposomes may enable selective drug release in the intracellular acidic compartments (endosomes, lysosomes). Thus, light activated liposomes with gold nanoparticles are an attractive option for time- and site-specific drug delivery into the target cells.

  14. Destruction thresholds of echogenic liposomes with clinical diagnostic ultrasound.

    PubMed

    Smith, Denise A B; Porter, Tyrone M; Martinez, Janet; Huang, Shaoling; MacDonald, Robert C; McPherson, David D; Holland, Christy K

    2007-05-01

    Echogenic liposomes (ELIP) are submicron-sized phospholipid vesicles that contain both gas and fluid. With antibody conjugation and drug incorporation, these liposomes can be used as novel targeted diagnostic and therapeutic ultrasound contrast agents. The utility of liposomes for contrast depends upon their stability in an acoustic field, whereas the use of liposomes for drug delivery requires the liberation of encapsulated gas and drug payload at the desired treatment site. The objective of this study was twofold: (1) to characterize the stability of liposome echogenicity after reconstitution and (2) to quantitate the acoustic destruction thresholds of liposomes as a function of peak rarefactional pressure (P(r)), pulse duration (PD) and pulse repetition frequency (PRF). The liposomes were insonified in an anechoic sample chamber using a Philips HDI 5000 diagnostic ultrasound scanner with a L12-5 linear array. Liposome stability was evaluated with 6.9-MHz fundamental and 4.5-MHz harmonic B-mode pulses at various P(r) at a fixed PRF. Liposome destruction thresholds were determined using 6.0-MHz Doppler pulses, by varying the PD with a fixed PRF of 1.25 kHz and by varying the PRF with a fixed PD of 3.33 micros. Videos or freeze-captured images were acquired during each insonation experiment and analyzed for echogenicity in a fixed region of interest as a function of time. An initial increase in echogenicity was observed for fundamental and harmonic B-mode imaging pulses. The threshold for acoustically driven diffusion of gas out of the liposomes using 6.0-MHz Doppler pulses was weakly dependent upon PRF and PD. The rapid fragmentation thresholds, however, were highly dependent upon PRF and PD. The quantification of acoustic destruction thresholds of ELIP is an important first step in their development as diagnostic and drug delivery agents.

  15. Mechanism of oligonucleotide release from cationic liposomes.

    PubMed Central

    Zelphati, O; Szoka, F C

    1996-01-01

    We propose a mechanism for oligonucleotide (ODN) release from cationic lipid complexes in cells that accounts for various observations on cationic lipid-nucleic acid-cell interactions. Fluorescent confocal microscopy of cells treated with rhodamine-labeled cationic liposome/ fluorescein-labeled ODN (F-ODN) complexes show the F-ODN separates from the lipid after internalization and enters the nucleus leaving the fluorescent lipid in cytoplasmic structures. ODN displacement from the complex was studied by fluorescent resonance energy transfer. Anionic liposome compositions (e.g., phosphatidylserine) that mimic the cytoplasmic facing monolayer of the cell membrane released ODN from the complex at about a 1:1 (-/+) charge ratio. Release was independent of ionic strength and pH. Physical separation of the F-ODN from monovalent and multivalent cationic lipids was confirmed by gel electrophoresis. Fluid but not solid phase anionic liposomes are required, whereas the physical state of the cationic lipids does not effect the release. Water soluble molecules with a high negative linear charge density, dextran sulfate, or heparin also release ODN. However, ATP, spermidine, spermine, tRNA, DNA, polyglutamic acid, polylysine, bovine serum albumin, or histone did not release ODN, even at 100-fold charge excess (-/+). Based upon these results, we propose that the complex, after internalization by endocytosis, induces flip-flop of anionic lipids from the cytoplasmic facing monolayer. Anionic lipids laterally diffuse into the complex and form a charged neutralized ion-pair with the cationic lipids. This leads to displacement of the ODN from the cationic lipid and its release into the cytoplasm. Images Fig. 1 Fig. 3 PMID:8876163

  16. Azaphenalene phthalocyanines: phthalocyanine analogues with six-membered-ring units instead of five-membered-ring units.

    PubMed

    Shimizu, Soji; Zhu, Hua; Kobayashi, Nagao

    2010-09-24

    Mixed-condensation reaction of 1,8-naphthalenedicarbonitrile and a 4,5-disubstituted phthalonitrile provided a series of phthalocyanine (Pc) analogues with azaphenalene (AP) moieties in place of the isoindole moieties. Monosubstituted species, APPc, and the two structural isomers of disubstituted species, adj-AP(2)Pc and opp-AP(2)Pc, were successfully isolated by gel-permeation chromatography on HPLC apparatus. Their structures were elucidated by (1)H NMR spectroscopy and X-ray crystallographic analysis. Replacement of the isoindole moieties with azaphenalene moieties created six-membered-ring units in the core and caused distortion of the molecular structures. The Q-band absorption shifted to the red upon an increase in the number of azaphenalene units; the shape of the absorption spectra depended on the molecular symmetries. APPc and opp-AP(2)Pc showed a large splitting of the Q band, whereas adj-AP(2)Pc exhibited a single broad Q band. These changes in the absorption spectra, as well as the unique electronic structures, are discussed in detail, based on magnetic circular dichroism spectra, electrochemical measurements, and density functional theory calculations.

  17. Immunological adjuvants: a role for liposomes.

    PubMed

    Gregoriadis, G

    1990-03-01

    Recent technological advances have resulted in the production of safe subunit and synthetic small peptide vaccines. These vaccines are weakly or non-immunogenic and cannot, therefore, be used effectively in the absence of immunological adjuvants (agents that can induce strong immunity to antigens). Owing to the toxicity of adjuvants, only one (aluminium salts) has hitherto been licensed for use in humans, and it is far from ideal. In this article, Gregory Gregoriadis discusses the use of liposomes as an alternative safe, versatile, universal adjuvant that can induce humoral- and cell-mediated immunity to antigens when administered parenterally or enterally. PMID:2186746

  18. Delivery of aerosolized drugs encapsulated in liposomes

    SciTech Connect

    Cheng, Yung-Sung; Lyons, C.R.; Schmid, M.H.

    1995-12-01

    Mycobacterium tuberculosis (Mtb) is an infectious disease that resides in the human lung. Due to the difficulty in completely killing off the disease in infected individuals, Mtb has developed drug-resistant forms and is on the rise in the human population. Therefore, ITRI and the University of New Mexico are collaborating to explore the treatment of Mtb by an aerosolized drug delivered directly to the lungs. In conclusion, it is feasible to obtain an appropriate size and concentration of the liposomes before and after aerosolization.

  19. Analysis of individual lipoproteins and liposomes

    SciTech Connect

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

    1997-08-01

    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.

  20. Towards clarifying the N-M vibrational nature of metallo-phthalocyanines. Infrared spectrum of phthalocyanine magnesium complex: density functional calculations.

    PubMed

    Zhang, Xianxi; Zhang, Yuexing; Jiang, Jianzhuang

    2004-08-01

    Infrared frequencies and intensities for the magnesium phthalocyanine complex MgPc have been calculated at density functional B3LYP level using the 6-31G(d) basis set. Detailed assignments of the metal-nitrogen (N-M) vibrational bands in the IR spectrum have been made on the basis of comparison of the calculated data of MgPc with the experimental result and also with that of H(2)Pc. The empirical controversial assignment of the characteristic band at 886-919 cm(-1) for metallo-phthalocyanines is also clearly interpreted. Nevertheless, the previous assignments of N-H stretchings, in-plane bending (IPB) and out-of-plane bending (OPB) modes made based on the comparative calculation of H(2)Pc and D(2)Pc are confirmed again by the present research result.

  1. Photochemistry of transition-metal phthalocyanines. Monophotonic and sequential biphotonic photochemical processes of copper(II) tetrakis(N-octadecylsulfamoyl)phthalocyanine in nonaqueous media

    SciTech Connect

    Prasad, D.R.; Ferraudi, G.

    1982-08-01

    The photochemistry of dimeric and monomeric copper(II) tetrakis(N-octadecylsulfamoyl)phthalocyanine in chloroform has been investigated by steady-state, flash and laser flash photolysis. The decay of a low-lying ..pi pi..* triplet-doublet with k approx. = 2 x 10/sup 7/ s/sup -1/ was observed in laser flash photolysis. Similar observations were carried out with related complexes. Moreover, long-lived transformations were assigned to the formation of a copper(III) phthalocyanine. Product yields were determined as a function of the excitation wavelength and light intensity. Excitations on the Q band, lambda approx. = 600 nm, with high intensities from a focused dye laser induce a photochemistry otherwise observed for excitations at lambda less than or equal to 350 nm. Mechanisms involving short-lived n..pi..* states and two-photon photochemistry involving a low-lying and long-lived ..pi pi..* triplet-doublet are discussed. 6 figures, 2 tables.

  2. Tetra methyl substituted Cu(II) phthalocyanine as alternative hole transporting material for organometal halide perovskite solar cells

    NASA Astrophysics Data System (ADS)

    Sfyri, Georgia; Kumar, Challuri Vijay; Wang, Yu-Long; Xu, Zong-Xiang; Krontiras, C. A.; Lianos, Panagiotis

    2016-01-01

    Copper phthalocyanine is a promising hole transporting material, which can be employed with solid state perovskite solar cells. Tetra methyl substituted copper phthalocyanine was presently studied as a hole transporting material and demonstrated improved performance with respect to unsubstituted copper phthalocyanine. This material shows a strong absorption in the Visible and Near IR part of the electromagnetic spectrum contributing to the absorption of photons. Its LUMO and HOMO level are favourably positioned for injecting electrons and scavenging holes. Methyl substitution facilitates closer molecular packing leading to a stronger extinction coefficient, stronger π-π interaction and higher charge carrier mobility.

  3. Spectroscopic studies of alpha tocopherol interaction with a model liposome and its influence on oxidation dynamics

    NASA Astrophysics Data System (ADS)

    Krilov, Dubravka; Kosović, Marin; Serec, Kristina

    2014-08-01

    The influence of α-tocopherol on the surface conformation of liposome, as a model component of lipoproteins, and its role in oxidation process were studied. FT-IR spectra from suspensions of neat liposome, mixtures of liposome and α-tocopherol and liposome with incorporated α-tocopherol were analyzed. When α-tocopherol was incorporated into liposome, intensities of some bands were decreased or increased in comparison with the spectra of liposome and α-tocopherol mixture. These changes reflect the different localization of α-tocopherol in two types of liposome suspensions. The oxidation of liposome suspensions was initiated by addition of cupric ions. After prolonged oxidation, the differences in FT-IR spectra of oxidized samples were recorded. Differences were observed in comparison with spectra of native and oxidized liposomes were analyzed. The rate of oxidation was measured by EPR oximetry. Oxidation was generally very slow, but faster in liposome without α-tocopherol, indicating the protective role of α-tocopherol against liposome oxidation. On the other hand, liposome suspensions with EDTA in the buffer were not oxidized at all, while those with α-tocopherol and liposome mixture were only slightly oxidized. In this case the consumption of oxygen was the result of liposome oxidation supported by α-tocopherol. These results reflect the ambivalent role of α-tocopherol in liposome oxidation, similarly to findings in studies of lipoprotein oxidation.

  4. Optical delivery of liposome encapsulated chemical stimuli to neuronal cells

    NASA Astrophysics Data System (ADS)

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

    2011-09-01

    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 μm (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.

  5. HPLC analysis as a tool for assessing targeted liposome composition.

    PubMed

    Oswald, Mira; Platscher, Michael; Geissler, Simon; Goepferich, Achim

    2016-01-30

    Functionalized phospholipids are indispensable materials for the design of targeted liposomes. Control over the quality and quantity of phospholipids is thereby key in the successful development and manufacture of such formulations. This was also the case for a complex liposomal preparation composed of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), Cholesterol (CHO), 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[amino(polyethylene glycol)-2000] (DSPE-PEG2000). To this end, an RP-HPLC method was developed. Detection was done via evaporative light scattering (ELS) for liposomal components. The method was validated for linearity, precision, accuracy, sensitivity and robustness. The liposomal compounds had a non-linear quadratic response in the concentration range of 0.012-0.42 mg/ml with a correlation coefficient greater than 0.99 with an accuracy of method confirmed 95-105% of the theoretical concentration. Furthermore, degradation products from the liposomal formulation could be identified. The presented method was successfully implemented as a control tool during the preparation of functionalized liposomes. It underlined the benefit of HPLC analysis of phospholipids during liposome preparation as an easy and rapid control method for the functionalized lipid at each preparation step as well as for the quantification of all components.

  6. Heparin octasaccharide decoy liposomes inhibit replication of multiple viruses

    PubMed Central

    Hendricks, Gabriel L.; Velazquez, Lourdes; Pham, Serena; Qaisar, Natasha; Delaney, James C.; Viswanathan, Karthik; Albers, Leila; Comolli, James C.; Shriver, Zachary; Knipe, David M.; Kurt-Jones, Evelyn A.; Fygenson, Deborah K.; Trevejo, Jose M.

    2016-01-01

    Heparan sulfate (HS) is a ubiquitous glycosaminoglycan that serves as a cellular attachment site for a number of significant human pathogens, including respiratory syncytial virus (RSV), human parainfluenza virus 3 (hPIV3), and herpes simplex virus (HSV). Decoy receptors can target pathogens by binding to the receptor pocket on viral attachment proteins, acting as ‘molecular sinks’ and preventing the pathogen from binding to susceptible host cells. Decoy receptors functionalized with HS could bind to pathogens and prevent infection, so we generated decoy liposomes displaying HS-octasaccharide (HS-octa). These decoy liposomes significantly inhibited RSV, hPIV3, and HSV infectivity in vitro to a greater degree than the original HS-octa building block. The degree of inhibition correlated with the density of HS-octa displayed on the liposome surface. Decoy liposomes with HS-octa inhibited infection of viruses to a greater extent than either full-length heparin or HS-octa alone. Decoy liposomes were effective when added prior to infection or following the initial infection of cells in vitro. By targeting the well-conserved receptor-binding sites of HS-binding viruses, decoy liposomes functionalized with HS-octa are a promising therapeutic antiviral agent and illustrate the utility of the liposome delivery platform. PMID:25637710

  7. Effect of liposomal amphotericin B on murine macrophages and lymphocytes.

    PubMed Central

    Mehta, R T; Mehta, K; Lopez-Berestein, G; Juliano, R L

    1985-01-01

    The effect of liposome-encapsulated amphotericin B on mouse macrophages and on T- and B-lymphocyte functions in vitro was compared with that of free amphotericin B. Liposomal amphotericin B was generally less toxic than the free form of the drug. Low concentrations of free amphotericin B completely inhibited the serum-dependent induction of transglutaminase, a marker for macrophage differentiation, and production of superoxide anion by macrophages, whereas encapsulation of the drug within liposomes protected the cells from these adverse effects. Liposomal amphotericin B did not affect the blastogenic response of T cells compared with the free drug, which was inhibitory at high concentrations. Antibody production in vivo was inhibited partially by both free and liposomal amphotericin B. These results thus suggest that encapsulation of amphotericin B in liposomes reduces the immunosuppressive effects exerted by free amphotericin B. This provides further justification for therapeutic use of liposomal amphotericin B in systemic fungal infections (G. Lopez-Berestein, R. Mehta, R. L. Hopfer, K. Mills, L. Kasi, K. Mehta, V. Fainstein, M. Luna, E. M. Hersh, and R. L. Juliano, J. Infect. Dis. 147:939-945, 1983). PMID:2578433

  8. Interface energetics in zinc phthalocyanine growth on Ag(100)

    NASA Astrophysics Data System (ADS)

    Al-Mahboob, Abdullah; Sadowski, Jerzy T.

    2016-02-01

    The nucleation and growth of zinc phthalocyanine (ZnPc) thin films on a Ag(100) surface are studied employing in situ, real-time low-energy electron microscopy and complementary density functional theory (DFT) calculation to elucidate the role of incorporation kinetics of planar molecules in phase selection during nucleation and apply this knowledge to the fabrication of highly crystalline ZnPc films. We show that the nucleation of crystalline ZnPc islands requires a large concentration of diffusing molecules. The required amount of nominal deposition to initiate the growth of monolayer (ML) high two-dimensional crystalline islands is dependent on both growth temperature and crystalline phase. At room temperature (RT) and slightly above (RT to ˜430 K), ZnPc crystalline islands have double-domain R 33.69 structures with average domain sizes in the submicrometer range. At higher temperatures, a 5 × 5 commensurate ZnPc structure nucleates. DFT calculations reveal significant differences in interfacial energies of an isolated ZnPc molecule on a substrate, depending on an adsorption site and azimuthal orientation of the molecule relative to the substrate atomic lattice. The observed delay in the onset of the nucleation of an island is caused by the existence of a large energy barrier for molecule incorporation into an island. At certain growth conditions it is possible to induce a structural transition from the 5 × 5 to the R 33.69 phase when the nominal coverage reaches 1 ML. The resulting film has excellent crystallinity with individual domains of hundreds of micrometers in size.

  9. Phthalocyanine-labeled LDL for tumor imaging and photodynamic therapy

    NASA Astrophysics Data System (ADS)

    Li, Hui; Marotta, Diane; Kim, Soungkyoo; Chance, Britton; Glickson, Jerry D.; Busch, Theresa M.; Zheng, Gang

    2005-01-01

    Current limitation of both near-infrared (NIR) tumor imaging and photodynamic therapy (PDT) is their lack of sufficient tumor-to-tissue contrast due to the relatively non-specific nature of delivering dye to the tumor, which has led to false negatives for NIR imaging and inadequate therapeutic ratio for PDT. Hence, agents targeting "cancer signatures", i.e. molecules that accumulate selectively in cancer cells, are particular attractive. One of these signatures is low-density-lipoprotein receptor (LDLR), which is overexpressed in many tumors. We have developed pyropheophorbide cholesterol oleate reconstituted LDL as a LDLR-targeting photosensitizer (PS) and demonstrated its LDLR-mediated uptake in vitro and in vivo. To improve the labeling efficiency for achieving high probe/protein ratio, tetra-t-butyl silicon phthalocyanine bearing two oleate moieties at its axial positions, (tBu)4SiPcBOA, was designed and synthesized. This compound was designed to 1) prevent the PS aggregation; 2) improve the PS solubility in non-polar solvent; and 3) maximize the PS binding to LDL phospholipid monolayer. Using this novel strategy, (tBu)4SiPcBOA was reconstituted into LDL (r-SiPcBOA-LDL) with a very high payload (500:1 molar ratio). In addition, (tBu)4SiPcBOA reconstituted acetylated LDL (r-SiPcBOA)-AcLDL with similar payload was also prepared. Since Ac-LDL cannot bind to LDLR, (r-SiPcBOA)-AcLDL can serve as the negative control to evaluate LDLR targeting specificity. For biological evaluation of these new agents, confocal microscopy and in vitro PDT protocols were performed using LDLR-overexpressing human hepatoblastoma G2 (HepG2) tumor model. These studies suggest that LDL serves as a delivery vehicle to bring large amount of the NIR/PDT agents selectively to tumor cells overexpressing LDLR.

  10. Tuning coercivity via iron chains in phthalocyanine thin films

    NASA Astrophysics Data System (ADS)

    Werber, Mathew Stephen

    We investigated the properties of magnetic hysteresis loops of Iron Phthalocyanine (FePc) thin films using a Vibrating Sample Magnetometer (VSM). The FePc thin films were deposited onto heated silicon substrates. During deposition the FePc molecules self-assemble into small crystallites ranging in size from 30 to 300 nm on average. Due to the planar shape of the molecule, chains of iron atoms are formed. The magnetic interaction within a chain is much stronger than between chains, making these thin films quasi-one-dimensional magnetic systems. The average length of the major axis of the grains increases with the temperature of the substrate (deposition temperature). Essentially the thin films are made up of many randomly oriented iron chains of variable length, which are parallel to the substrate surface. We show that the coercivity of hysteresis loops measured at 2 K increases linearly with the average major axis grain length. From interpolation, the minimum average grain length for hysteresis to occur is 8 nm, and every additional nano-meter in length increases the coercivity by 72 Oe. By measuring hysteresis loops of many thin films of varying thickness we found that the saturation magnetization is 31 emu/cm3. This corresponds to 2.0 +/- 0.6 micro B per iron ion, as compared to 2.22 microB for iron in a 3D lattice at 0 K. The choice of substrate also affects the hysteresis properties. Samples deposited on silicon substrates that had first been coated in gold with a rms roughness of approximately 1 nm will show much lower coercivity than corresponding silicon substrate samples. The planar gold surface allows for a different growth pattern in which the chains form vertically, perpendicular to the substrate. This lower coercivity suggests that the chains are shorter when vertically oriented.

  11. Droplet-Based Production of Liposomes

    NASA Technical Reports Server (NTRS)

    Ackley, Donald E.; Forster, Anita

    2009-01-01

    A process for making monodisperse liposomes having lipid bilayer membranes involves fewer, simpler process steps than do related prior methods. First, a microfluidic, cross junction droplet generator is used to produce vesicles comprising aqueous solution droplets contained in single layer lipid membranes. The vesicles are collected in a lipid-solvent mix that is at most partially soluble in water and is less dense than is water. A layer of water is dispensed on top of the solvent. By virtue of the difference in densities, the water sinks to the bottom and the solvent floats to the top. The vesicles, which have almost the same density as that of water, become exchanged into the water instead of floating to the top. As there are excess lipids in the solvent solution, in order for the vesicles to remain in the water, the addition of a second lipid layer to each vesicle is energetically favored. The resulting lipid bilayers present the hydrophilic ends of the lipid molecules to both the inner and outer membrane surfaces. If lipids of a second kind are dissolved in the solvent in sufficient excess before use, then asymmetric liposomes may be formed.

  12. Photophysical efficiency-boost of aqueous aluminium phthalocyanine by hybrid formation with nano-clays.

    PubMed

    Staniford, Mark C; Lezhnina, Marina M; Gruener, Malte; Stegemann, Linda; Kuczius, Rauni; Bleicher, Vera; Strassert, Cristian A; Kynast, Ulrich H

    2015-09-11

    Novel organic-inorganic hybrid materials comprising nanoscaled layered silicates and native aluminium hydroxide phthalocyanine (Al(OH)Pc) allowed for the first time the exploitation of their unique photophysical properties in aqueous ambience. In particular, we were able to observe the efficient emission of Al(OH)Pc-nanoclay hybrids and generation of singlet oxygen in aqueous solution.

  13. Well-defined, persistent, chiral phthalocyanine nanoclusters via G-quadruplex assembly.

    PubMed

    García-Iglesias, Miguel; Torres, Tomas; González-Rodríguez, David

    2016-07-19

    Octameric near-IR dye nanoclusters are produced by complexation of potassium cations with a phthalocyanine-guanosine conjugate. The combination of hydrogen-bonding, K(+) coordination, π-π stacking and steric interactions between the chiral side groups is responsible for defining a specific helical chromophore arrangement in the clusters, which display high stability and maintain their supramolecular identity onto substrates. PMID:27377372

  14. Synthesis and nonlinear optical properties of sol-gel materials containing phthalocyanines

    NASA Astrophysics Data System (ADS)

    Fuqua, Peter D.; Mansour, Kamjou; Alvarez, Daniel, Jr.; Marder, Seth R.; Perry, Joseph W.; Dunn, Bruce S.

    1992-12-01

    Optical limiters are devices that have the ability to limit the intensity of light that passes through them. They function like 'optical surge protectors,' blocking a greater fraction of photons when the incident light intensity is very high than when the incident intensity is low. This might allow an electronic sensor or a human eye to function under ambient lighting conditions and yet be protected from being blinded by direct laser illumination. Phthalocyanine (Pc) dyes which exhibit nonlinear optical behavior known as reverse saturable absorption (RSA) have been demonstrated to be effective in solution-based optical limiters. There is considerable interest in the possibility of fabricating optical limiters based on solid-state materials containing phthalocyanine dyes. Sol-gel processing is a solution based technique for preparing porous metal oxide monoliths at low temperatures. By adding an organic dye to the precursor solution, one can trap these organic molecules in the pores of a silica host. These potentially thermally stable materials are of interest for the fabrication of monolithic lens/limiter optical components. Our study of sol-gel synthetic approaches to phthalocyanine doped glassy materials show that phthalocyanine dyes in silica hosts are stable and exhibit optical nonlinearities comparable to those of the corresponding dye solutions.

  15. Phthalocyanine derivatives possessing 2-(morpholin-4-yl)ethoxy groups as potential agents for photodynamic therapy.

    PubMed

    Kucinska, Malgorzata; Skupin-Mrugalska, Paulina; Szczolko, Wojciech; Sobotta, Lukasz; Sciepura, Mateusz; Tykarska, Ewa; Wierzchowski, Marcin; Teubert, Anna; Fedoruk-Wyszomirska, Agnieszka; Wyszko, Eliza; Gdaniec, Maria; Kaczmarek, Mariusz; Goslinski, Tomasz; Mielcarek, Jadwiga; Murias, Marek

    2015-03-12

    Three 2-(morpholin-4-yl)ethoxy substituted phthalocyanines were synthesized and characterized. Phthalocyanine derivatives revealed moderate to high quantum yields of singlet oxygen production depending on the solvent applied (e.g., in DMF ranging from 0.25 to 0.53). Their photosensitizing potential for photodynamic therapy was investigated in an in vitro model using cancer cell lines. Biological test results were found particularly encouraging for the zinc(II) phthalocyanine derivative possessing two 2-(morpholin-4-yl)ethoxy substituents in nonperipheral positions. Cells irradiated for 20 min at 2 mW/cm(2) revealed the lowest IC50 value at 0.25 μM for prostate cell line (PC3), whereas 1.47 μM was observed for human malignant melanoma (A375) cells. The cytotoxic activity in nonirradiated cells of novel phthalocyanine was found to be very low. Moreover, the cellular uptake, localization, cell cycle, apoptosis through an ELISA assay, and immunochemistry method were investigated in LNCaP cells. Our results showed that the tested photosensitizer possesses very interesting biological activity, depending on experimental conditions.

  16. Towards Clarifying the Role of O2 during the Phthalocyanine Synthesis.

    PubMed

    Wang, Kang; Pan, Houhe; Jiang, Jianzhuang

    2015-12-01

    The role of O2 within the synthesis of phthalocyanines (Pcs) has remained unclear in the past century. Here, we demonstrate that O2 , in cooperation with the solvent n-pentanol, participates in the cyclic tetramerization of phthalonitriles over the half-sandwich complex template [Lu(Pc)(acac)] (acac=acetylacetonate) and terminates the reaction at the stage of uncyclized isoindole oligomeric derivatives rather than the phthalocyanine chromophores, resulting in the isolation of the heteroleptic (phthalocyaninato)(triisoindole-1-one) lutetium double-decker complexes [(Pc)Lu(TIO-I)] (TIO-I=3,4,7,8,11,12-sexi(2,6-diisopropylphenoxy)-15-[4,5-di(2,6-diisopropylphenoxy)-2-cyanobenzimidamido]triisoindole-1-one) and [(Pc)Lu(TIO-II)] (TIO-II=3,4,7,8,11,12-sexi(2,6-dimethylphenoxy)-15-[4,5-di(2,6-dimethylphenoxy)-2-cyanobenzimidamido]triisoindole-1-one) with the help of bulky substituents at the phthalonitrile periphery and an unsubstituted phthalocyanine ligand in the double-decker skeleton. Nevertheless, the cyclic tetramerization of the phthalonitriles was revealed to be sensitive to O2 with the reaction progression also depending on the oxygen concentration/content, leading to the O2 -senstive and -dependent nature for the isolation of phthalocyanine derivatives.

  17. Electrostatic binding of substituted metal phthalocyanines to enterobacterial cells: its role in photodynamic inactivation.

    PubMed

    Strakhovskaya, M G; Antonenko, Y N; Pashkovskaya, A A; Kotova, E A; Kireev, V; Zhukhovitsky, V G; Kuznetsova, N A; Yuzhakova, O A; Negrimovsky, V M; Rubin, A B

    2009-12-01

    The effect of ionic substituents in zinc and aluminum phthalocyanine molecules and of membrane surface charge on the interaction of dyes with artificial membranes and enterobacterial cells, as well as on photosensitization efficiency was studied. It has been shown that increasing the number of positively charged substituents enhances the extent of phthalocyanine binding to Escherichia coli cells. This, along with the high quantum yield of singlet oxygen generation, determines efficient photodynamic inactivation of Gram-negative bacteria by zinc and aluminum octacationic phthalocyanines. The effect of Ca2+ and Mg2+ cations and pH on photodynamic inactivation of enterobacteria in the presence of octacationic zinc phthalocyanine has been studied. It has been shown that effects resulting in lowering negative charge on outer membrane protect bacteria against photoinactivation, which confirms the crucial role in this process of the electrostatic interaction of the photosensitizer with the cell wall. Electrostatic nature of binding is consistent with mainly electrostatic character of dye interactions with artificial membranes of different composition. Lower sensitivity of Proteus mirabilis to photodynamic inactivation, compared to that of E. coli and Salmonella enteritidis, due to low affinity of the cationic dye to the cells of this species, was found.

  18. Interaction of cationic phthalocyanines with DNA. Importance of the structure of the substituents.

    PubMed

    López Zeballos, N C; Gauna, G A; García Vior, M C; Awruch, J; Dicelio, L E

    2014-07-01

    The interaction of novel zinc (II) cationic phthalocyanines with CT-DNA was studied using absorption and fluorescence spectroscopy, as well as thermal denaturation profiles. Results showed an electrostatic interaction between the phthalocyanines and CT-DNA. The properties of these phthalocyanines were compared taking the structure of the macrocycle peripheral substituents into account. 2,9(10),16(17),23(24)-tetrakis[(N-butyl-N-methylammonium)ethylsulfanyl]phthalocyaninatozinc(II) tetraiodide (Pc6) had a greater affinity for the CT-DNA helix than its bioisoster 2,9(10),16(17),23(24)-tetrakis[(N-dibutyl-N-methylammonium)ethoxy]phthalocyaninatozinc(II) tetraiodide (Pc7). 2,9(10),16(17),23(24)-tetrakis[(2-trimethylammonium)ethyl-sulfanyl]phthalocyaninatozinc(II) tetraiodide (Pc13) also carried a sulfur atom like Pc6, but linked to bulky substituents such as trimethylammonium groups. The planar aromatic region of the cationic phthalocyanines in this study appears to be unable to facilitate their intercalation with CT-DNA.

  19. A rapid safranin-metal phthalocyanine double staining technique for plants.

    PubMed

    Achar, B N; Bhandari, J M; Urs, H G

    1993-05-01

    Pure metal 4,4',4'',4'''-tetra-substituted, sulfo-, carboxy- and nitrophthalocyanines were synthesized. Mounted, deparaffinized and partially dehydrated sections of plant tissues were stained with 0.5% safranin in 50% alcohol for 5-10 min. Excess safranin was removed with a series of 70%, 95% and absolute alcohol washes. The sections were then stained for 2-3 min using metal 4,4',4'',4'''-phthalocyanine tetracarboxylic acid (MPTC, 0.5% (V/V) containing a few drops of dilute sodium hydroxide), metal 4,4',4'',4'''-tetrasulfophthalocyanine (MPTS, 0.5% (V/V)) or metal tetranitrophthalocyanine (MPTN, 0.5% (V/V) in dimethyl sulfoxide). The sections were washed with 95%, then absolute alcohol; however, the metal tetranitrophthalocyanine section was washed only with absolute alcohol. Stained sections were treated briefly with xylene, then mounted on a coverslip. Bright peacock blue (MPTC and MPTS using Cu, Co or Ni), turquoise blue (MPTN using Cu or Ni) or parrot green (zinc phthalocyanine tetracarboxylic acid-ZnPTC, zinc phthalocyanine tetranitro derivative-ZnPTN) colors were obtained. Lignin-containing cells were stained red by safranin and the remaining cell structures were stained by the metal phthalocyanine complex with color brightness superior to that of fast green. Uniform staining, no color fading after a year, reliability, brief staining times, high color contrast (log epsilon = 4.0-4.9) and ease of use make this double staining combination ideal for routine use and photomicrography.

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

    NASA Astrophysics Data System (ADS)

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

    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.

  1. Spectroscopic fingerprints of work-function-controlled phthalocyanine charging on metal surfaces.

    PubMed

    Borghetti, Patrizia; El-Sayed, Afaf; Goiri, Elizabeth; Rogero, Celia; Lobo-Checa, Jorge; Floreano, Luca; Ortega, Jose Enrique; de Oteyza, Dimas G

    2014-12-23

    The electronic character of a π-conjugated molecular overlayer on a metal surface can change from semiconducting to metallic, depending on how molecular orbitals arrange with respect to the electrode's Fermi level. Molecular level alignment is thus a key property that strongly influences the performance of organic-based devices. In this work, we report how the electronic level alignment of copper phthalocyanines on metal surfaces can be tailored by controlling the substrate work function. We even show the way to finely tune it for one fixed phthalocyanine-metal combination without the need to intercalate substrate-functionalizing buffer layers. Instead, the work function is trimmed by appropriate design of the phthalocyanine's supramolecular environment, such that charge transfer into empty molecular levels can be triggered across the metal-organic interface. These intriguing observations are the outcome of a powerful combination of surface-sensitive electron spectroscopies, which further reveal a number of characteristic spectroscopic fingerprints of a lifted LUMO degeneracy associated with the partial phthalocyanine charging. PMID:25426520

  2. Photophysical efficiency-boost of aqueous aluminium phthalocyanine by hybrid formation with nano-clays.

    PubMed

    Staniford, Mark C; Lezhnina, Marina M; Gruener, Malte; Stegemann, Linda; Kuczius, Rauni; Bleicher, Vera; Strassert, Cristian A; Kynast, Ulrich H

    2015-09-11

    Novel organic-inorganic hybrid materials comprising nanoscaled layered silicates and native aluminium hydroxide phthalocyanine (Al(OH)Pc) allowed for the first time the exploitation of their unique photophysical properties in aqueous ambience. In particular, we were able to observe the efficient emission of Al(OH)Pc-nanoclay hybrids and generation of singlet oxygen in aqueous solution. PMID:26221639

  3. Copper phthalocyanine as an efficient dopant in development of solar cells

    SciTech Connect

    Inigo, A.R.; Xavier, F.P.; Goldsmith, G.J.

    1997-05-01

    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.

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

    SciTech Connect

    Carrado, K.A.; Botto, R.E.; Winans, R.E. ); Forman, J.E. )

    1993-04-01

    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.

  5. Towards Clarifying the Role of O2 during the Phthalocyanine Synthesis.

    PubMed

    Wang, Kang; Pan, Houhe; Jiang, Jianzhuang

    2015-12-01

    The role of O2 within the synthesis of phthalocyanines (Pcs) has remained unclear in the past century. Here, we demonstrate that O2 , in cooperation with the solvent n-pentanol, participates in the cyclic tetramerization of phthalonitriles over the half-sandwich complex template [Lu(Pc)(acac)] (acac=acetylacetonate) and terminates the reaction at the stage of uncyclized isoindole oligomeric derivatives rather than the phthalocyanine chromophores, resulting in the isolation of the heteroleptic (phthalocyaninato)(triisoindole-1-one) lutetium double-decker complexes [(Pc)Lu(TIO-I)] (TIO-I=3,4,7,8,11,12-sexi(2,6-diisopropylphenoxy)-15-[4,5-di(2,6-diisopropylphenoxy)-2-cyanobenzimidamido]triisoindole-1-one) and [(Pc)Lu(TIO-II)] (TIO-II=3,4,7,8,11,12-sexi(2,6-dimethylphenoxy)-15-[4,5-di(2,6-dimethylphenoxy)-2-cyanobenzimidamido]triisoindole-1-one) with the help of bulky substituents at the phthalonitrile periphery and an unsubstituted phthalocyanine ligand in the double-decker skeleton. Nevertheless, the cyclic tetramerization of the phthalonitriles was revealed to be sensitive to O2 with the reaction progression also depending on the oxygen concentration/content, leading to the O2 -senstive and -dependent nature for the isolation of phthalocyanine derivatives. PMID:26526528

  6. High-performance optical limiters based on stable phthalocyanine J-type dimers

    NASA Astrophysics Data System (ADS)

    Tolbin, Alexander Yu.; Savelyev, Mikhail S.; Gerasimenko, Alexander Yu.; Tomilova, Larisa G.

    2016-09-01

    Low limiting thresholds have been demonstrated on thermally stable phthalocyanine J-type dimeric complexes of Mg and Zn. The effective "threshold" model based on radiative transfer phenomena in nonlinear optical (NLO) media was suggested for exact definition of the nonlinear absorption coefficient and the optical limiting threshold.

  7. Metal-organic magnetic materials based on cobalt phthalocyanine and possibilities of their application in medicine

    NASA Astrophysics Data System (ADS)

    Harutyunyan, Avetik R.; Kuznetsov, Anatoly A.; Kuznetsov, Oleg A.; Kaliya, O. L.

    1999-04-01

    Cobalt phthalocyanines (CoPc), doped with sodium, exhibit ferromagnetic ordering at room temperature. Magnetic dilution or variation in dopant concentration leads to the formation of new magnetic materials. A proposed scheme of oncological disease treatment includes magnetic concentration of CoPc particles in the tumor zone and ascorbic acid injection into the organism for stimulation of oxidation reactions, which destroy the tumor.

  8. Fabrication and characterization of organic solar cells using metal complex of phthalocyanines

    SciTech Connect

    Kida, Tomoyasu Suzuki, Atsushi Akiyama, Tsuyoshi Oku, Takeo

    2015-02-27

    Fabrication and characterization of organic solar cells using shuttle-cock-type phthalocyanines were carried out. Photovoltaic properties of the solar cells with inverted structures were investigated by current density-voltage characteristics. Effects of phase transition between H and J aggregates on the photovoltaic and optical properties were investigated. The photovoltaic mechanisms, energy levels and band gap of active layers were discussed.

  9. Giant Liposome Preparation for Imaging and Patch-Clamp Electrophysiology

    PubMed Central

    Collins, Marcus D.; Gordon, Sharona E.

    2013-01-01

    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 μm 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

  10. RGD-TPGS decorated theranostic liposomes for brain targeted delivery.

    PubMed

    Sonali; Singh, Rahul Pratap; Sharma, Gunjan; Kumari, Lakshmi; Koch, Biplob; Singh, Sanjay; Bharti, Shreekant; Rajinikanth, Paruvathanahalli Siddalingam; Pandey, Bajarangprasad L; Muthu, Madaswamy S

    2016-11-01

    The aim of this work was to formulate RGD-TPGS decorated theranostic liposomes, which contain both docetaxel (DTX) and quantum dots (QDs) for brain cancer imaging and therapy. RGD conjugated TPGS (RGD-TPGS) was synthesized and conjugation was confirmed by Fourier transform infrared (FTIR) spectroscopy and electrospray ionisation (ESI) mass spectroscopy (ESI-MS). The theranostic liposomes were prepared by the solvent injection method and characterized for their particle size, polydispersity, zeta-potential, surface morphology, drug encapsulation efficiency, and in-vitro release study. Biocompatibility and safety of theranostic liposomes were studied by reactive oxygen species (ROS) generation study and histopathology of brain. In-vivo study was performed for determination of brain theranostic effects in comparison with marketed formulation (Docel™) and free QDs. The particle sizes of the non-targeted and targeted theranostic liposomes were found in between 100 and 200nm. About 70% of drug encapsulation efficiency was achieved with liposomes. The drug release from RGD-TPGS decorated liposomes was sustained for more than 72h with 80% of drug release. The in-vivo results demonstrated that RGD-TPGS decorated theranostic liposomes were 6.47- and 6.98-fold more effective than Docel™ after 2h and 4h treatments, respectively. Further, RGD-TPGS decorated theranostic liposomes has reduced ROS generation effectively, and did not show any signs of brain damage or edema in brain histopathology. The results of this study have indicated that RGD-TPGS decorated theranostic liposomes are promising carrier for brain theranostics.

  11. Toxicity and immunogenicity of Neisseria meningitidis lipopolysaccharide incorporated into liposomes.

    PubMed

    Petrov, A B; Semenov, B F; Vartanyan, Y P; Zakirov, M M; Torchilin, V P; Trubetskoy, V S; Koshkina, N V; L'Vov, V L; Verner, I K; Lopyrev, I V

    1992-09-01

    To obtain nontoxic and highly immunogenic lipopolysaccharide (LPS) for immunization, we incorporated Neisseria meningitidis LPS into liposomes. Native LPS and its salts were incorporated by the method of dehydration-rehydration of vesicles or prolonged cosonication. The most complete incorporation of LPS into liposomes and a decrease in toxicity were achieved by the method of dehydration-rehydration of vesicles. Three forms of LPS (H+ form, Mg2+ salt, and triethanolamine salt) showed different solubilities in water, the acidic form of LPS, with the most pronounced hydrophobic properties, being capable of practically complete association with liposomal membranes. An evaluation of the activity of liposomal LPS in vitro (by the Limulus amoebocyte test) and in vivo (by monitoring the pyrogenic reaction in rabbits) revealed a decrease in endotoxin activity of up to 1,000-fold. In addition, the pyrogenic activity of liposomal LPS was comparable to that of a meningococcal polysaccharide vaccine. Liposomes had a pronounced adjuvant effect on the immune response to LPS. Thus, the level of anti-LPS plaque-forming cells in the spleens of mice immunized with liposomal LPS was 1 order of magnitude higher and could be observed for a longer time (until day 21, i.e., the term of observation) than in mice immunized with free LPS. The same regularity was revealed in a study done with an enzyme-linked immunosorbent assay. This study also established that antibodies induced by immunization belonged to the immunoglobulin M and G classes, which are capable of prolonged circulation. Moreover, liposomal LPS induced a pronounced immune response in CBA/N mice (defective in B lymphocytes of the LyB-5+ subpopulation). The latter results indicate that the immunogenic action of liposomal LPS occurs at an early age.

  12. Toxicity and immunogenicity of Neisseria meningitidis lipopolysaccharide incorporated into liposomes.

    PubMed Central

    Petrov, A B; Semenov, B F; Vartanyan, Y P; Zakirov, M M; Torchilin, V P; Trubetskoy, V S; Koshkina, N V; L'Vov, V L; Verner, I K; Lopyrev, I V

    1992-01-01

    To obtain nontoxic and highly immunogenic lipopolysaccharide (LPS) for immunization, we incorporated Neisseria meningitidis LPS into liposomes. Native LPS and its salts were incorporated by the method of dehydration-rehydration of vesicles or prolonged cosonication. The most complete incorporation of LPS into liposomes and a decrease in toxicity were achieved by the method of dehydration-rehydration of vesicles. Three forms of LPS (H+ form, Mg2+ salt, and triethanolamine salt) showed different solubilities in water, the acidic form of LPS, with the most pronounced hydrophobic properties, being capable of practically complete association with liposomal membranes. An evaluation of the activity of liposomal LPS in vitro (by the Limulus amoebocyte test) and in vivo (by monitoring the pyrogenic reaction in rabbits) revealed a decrease in endotoxin activity of up to 1,000-fold. In addition, the pyrogenic activity of liposomal LPS was comparable to that of a meningococcal polysaccharide vaccine. Liposomes had a pronounced adjuvant effect on the immune response to LPS. Thus, the level of anti-LPS plaque-forming cells in the spleens of mice immunized with liposomal LPS was 1 order of magnitude higher and could be observed for a longer time (until day 21, i.e., the term of observation) than in mice immunized with free LPS. The same regularity was revealed in a study done with an enzyme-linked immunosorbent assay. This study also established that antibodies induced by immunization belonged to the immunoglobulin M and G classes, which are capable of prolonged circulation. Moreover, liposomal LPS induced a pronounced immune response in CBA/N mice (defective in B lymphocytes of the LyB-5+ subpopulation). The latter results indicate that the immunogenic action of liposomal LPS occurs at an early age. PMID:1500196

  13. Enzymatic action of phospholipase A₂ on liposomal drug delivery systems.

    PubMed

    Hansen, Anders H; Mouritsen, Ole G; Arouri, Ahmad

    2015-08-01

    The overexpression of secretory phospholipase A2 (sPLA2) in tumors has opened new avenues for enzyme-triggered active unloading of liposomal antitumor drug carriers selectively at the target tumor. However, the effects of the liposome composition, drug encapsulation, and tumor microenvironment on the activity of sPLA2 are still not well understood. We carried out a physico-chemical study to characterize the sPLA2-assisted breakdown of liposomes using dye-release assays in the context of drug delivery and under physiologically relevant conditions. The influence of temperature, lipid concentration, enzyme concentration, and drug loading on the hydrolysis of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC, Tm=42°C) liposomes with snake venom sPLA2 was investigated. The sensitivity of human sPLA2 to the liposome composition was checked using binary lipid mixtures of phosphatidylcholine (PC) and phosphatidylglycerol (PG) phospholipids with C14 and C16 acyl chains. Increasing temperature (36-41°C) was found to mainly shorten the enzyme lag-time, whereas the effect on lipid hydrolysis rate was modest. The enzyme lag-time was also found to be inversely dependent on the lipid-to-enzyme ratio. Drug encapsulation can alter the hydrolysis profile of the carrier liposomes. The activity of human sPLA2 was highly sensitive to the phospholipid acyl-chain length and negative surface charge density of the liposomes. We believe our work will prove useful for the optimization of sPLA2-susceptible liposomal formulations as well as will provide a solid ground for predicting the hydrolysis profile of the liposomes in vivo at the target site.

  14. Second generation liposomal cancer therapeutics: transition from laboratory to clinic.

    PubMed

    Sen, Kacoli; Mandal, Mahitosh

    2013-05-01

    Recent innovations and developments in nanotechnology have revolutionized cancer therapeutics. Engineered nanomaterials are the current workhorses in the emerging field of cancer nano-therapeutics. Lipid vesicles bearing anti-tumor drugs have turned out to be a clinically feasible and promising nano-therapeutic approach to treat cancer. Efficient entrapment of therapeutics, biocompatibility, biodegradability, low systemic toxicity, low immunogenicity and ability to bypass multidrug resistance mechanisms has made liposomes a versatile drug/gene delivery system in cancer chemotherapy. The present review attempts to explore the recent key advances in liposomal research and the vast arsenal of liposomal formulations currently being utilized in treatment and diagnosis of cancer.

  15. In vivo and in vitro evaluation of octyl methoxycinnamate liposomes

    PubMed Central

    Varjão Mota, Aline de Carvalho; Faria de Freitas, Zaida Maria; Júnior, Eduardo Ricci; Dellamora-Ortiz, Gisela Maria; Santos-Oliveira, Ralph; Ozzetti, Rafael Antonio; Vergnanini, André Luiz; Ribeiro, Vanessa Lira; Silva, Ronald Santos; dos Santos, Elisabete Pereira

    2013-01-01

    Solar radiation causes damage to human skin, and photoprotection is the main way to prevent these harmful effects. The development of sunscreen formulations containing nanosystems is of great interest in the pharmaceutical and cosmetic industries because of the many potential benefits. This study aimed to develop and evaluate an octyl methoxycinnamate (OMC) liposomal nanosystem (liposome/OMC) to obtain a sunscreen formulation with improved safety and efficacy by retaining OMC for longer on the stratum corneum. Methods The liposome/OMC nanostructure obtained was tested for enzymatic hydrolysis with lipase from Rhizomucor miehei and biodistribution with liposomes labeled with technetium-99m. The liposome/OMC formulation was then incorporated in a gel formulation and tested for ocular irritation using the hen’s egg test-chorio-allantoic membrane (HET-CAM) assay, in vitro and in vivo sun protection factor, in vitro release profile, skin biometrics, and in vivo tape stripping. Results The liposome/OMC nanosystem was not hydrolyzed from R. miehei by lipase. In the biodistribution assay, the liposome/OMC formulation labeled with technetium-99m had mainly deposited in the skin, while for OMC the main organ was the liver, showing that the liposome had higher affinity for the skin than OMC. The liposome/OMC formulation was classified as nonirritating in the HET-CAM test, indicating good histocompatibility. The formulation containing liposome/OMC had a higher in vivo solar photoprotection factor, but did not show increased water resistance. Inclusion in liposomes was able to slow down the release of OMC from the formulation, with a lower steady-state flux (3.9 ± 0.33 μg/cm2/hour) compared with the conventional formulation (6.3 ± 1.21 μg/cm2/hour). The stripping method showed increased uptake of OMC in the stratum corneum, giving an amount of 22.64 ± 7.55 μg/cm2 of OMC, which was higher than the amount found for the conventional formulation (14.57 ± 2.30 μg/cm2

  16. Liposome production by microfluidics: potential and limiting factors

    PubMed Central

    Carugo, Dario; Bottaro, Elisabetta; Owen, Joshua; Stride, Eleanor; Nastruzzi, Claudio

    2016-01-01

    This paper provides an analysis of microfluidic techniques for the production of nanoscale lipid-based vesicular systems. In particular we focus on the key issues associated with the microfluidic production of liposomes. These include, but are not limited to, the role of lipid formulation, lipid concentration, residual amount of solvent, production method (including microchannel architecture), and drug loading in determining liposome characteristics. Furthermore, we propose microfluidic architectures for the mass production of liposomes with a view to potential industrial translation of this technology. PMID:27194474

  17. Liposomal Drug Products: A Quality by Design Approach

    NASA Astrophysics Data System (ADS)

    Xu, Xiaoming

    Quality by Design (QbD) principles has been applied to the development of two liposomal formulations, containing a hydrophilic small molecule therapeutic (Tenofovir) and a protein therapeutic (superoxide dismutase). The goal of the research is to provide critical information on 1) how to reduce the preparation variability in liposome formulations, and 2) how to increase drug encapsulation inside liposomes to reduce manufacturing cost. Most notably, an improved liposome preparation method was developed which increased the encapsulation efficiency of hydrophilic molecules. In particular, this method allows for very high encapsulation efficiency. For example, encapsulation efficiencies of up to 50% have been achieved, whereas previously only 20% or less have been reported. Another significant outcome from this research is a first principle mathematical model to predict the encapsulation efficiency of hydrophilic drugs in unilamellar liposomes. This mathematical model will be useful in: formulation development to rapidly achieve optimized formulations; comparison of drug encapsulation efficiencies of liposomes prepared using different methods; and assisting in the development of suitable process analytical technologies to achieve real-time monitoring and control of drug encapsulation during manufacturing. A novel two-stage reverse dialysis in vitro release testing method has also been developed for passively targeted liposomes, which uses the first stage to mimic the circulation of liposomes in the body and the second stage to imitate the drug release process at the target. The developed in vitro release testing method can be used to distinguish formulations with varied compositions for quality control testing purposes. This developed method may pave the way to the development of more biorelevant quality control testing methods for liposomal drug products in the future. The QbD case studies performed in this research are examples of how this approach can be used to

  18. Application of liposomes in medicine and drug delivery.

    PubMed

    Daraee, Hadis; Etemadi, Ali; Kouhi, Mohammad; Alimirzalu, Samira; Akbarzadeh, Abolfazl

    2016-01-01

    Liposomes provide an established basis for the sustainable development of different commercial products for treatment of medical diseases by the smart delivery of drugs. The industrial applications include the use of liposomes as drug delivery vehicles in medicine, adjuvants in vaccination, signal enhancers/carriers in medical diagnostics and analytical biochemistry, solubilizers for various ingredients as well as support matrices for various ingredients and penetration enhancers in cosmetics. In this review, we summarize the main applications and liposome-based commercial products that are currently used in the medical field.

  19. Meta-analysis of inter-patient pharmacokinetic variability of liposomal and non-liposomal anticancer agents

    PubMed Central

    Schell, Ryan F.; Sidone, Brian J.; Caron, Whitney P.; Walsh, Mark D.; Zamboni, Beth A.; Ramanathan, Ramesh K.; Zamboni, William C.

    2013-01-01

    Purpose A meta-analysis was conducted to evaluate the inter-patient pharmacokinetic (PK) variability of liposomal and small molecule (SM) anticancer agents. Methods Inter-patient PK variability of 9 liposomal and SM formulations of the same drug were evaluated. PK variability was measured as coefficient of variance (CV%) of area under the plasma concentration versus time curve (AUC) and the fold-difference between AUCmax and AUCmin (AUC range). Results CV% of AUC and AUC ranges were 2.7-fold (P<0.001) and 16.7-fold (P=0.13) greater, respectively, for liposomal compared with SM drugs. There was an inverse linear relationship between the clearance (CL) of liposomal agents and PK variability with a lower CL associated with greater PK variability (R2 = 0.39). PK variability of liposomal agents was greater when evaluated from 0–336 h compared with 0–24 h. Conclusion PK variability of liposomes is significantly greater than SM. The factors associated with the PK variability of liposomal agents needs to be evaluated. PMID:23891988

  20. [Spectrum characterization and fine structure of copper phthalocyanine-doped TiO2 microcavities].

    PubMed

    Liu, Cheng-lin; Zhang, Xin-yi; Zhong, Ju-hua; Zhu, Yi-hua; He, Bo; Wei, Shi-qiang

    2007-10-01

    Copper phthalocyanine-doped TiO2 microcavities were fabricated by chemistry method. Their spectrum characterization was studied by Fourier transform infrared (FTIR) and Raman spectroscopy, and their fine structure was analyzed by X-ray absorption fine structure (XAFS). The results show that there is interaction of copper phthalocyanine (CuPc) and TiO2 microcavities after TiO2 microcavities was doped with CuPc. For example, there is absorption at 900.76 cm(-1) in FTIR spectra, and the "red shift" of both OH vibration at 3392.75 cm(-1) and CH vibration at 2848.83 cm(-1). There exist definite peak shifts and intensity changes in infrared absorption in the C-C or C-N vibration in the planar phthalocyanine ring, the winding vibration of C-H inside and C-N outside plane of benzene ring. In Raman spectrum, there are 403.4, 592.1 and 679.1 cm(-1) characterized peaks of TiO2 in CuPc-doped TiO2 microcavities, but their wave-numbers show shifts to anatase TiO2. The vibration peaks at 1586.8 and 1525.6 cm(-1) show that there exists the composite material of CuPc and TiO2. These changes are related to the plane tropism of the molecule structure of copper phthalocyanine. XAFS showed tetrahedron TiO4 structure of Ti in TiO2 microcavities doped with copper phthalocyanine, and the changes of inner "medial distances" and the surface structure of TiO2 microcavities.

  1. Near Infrared Phosphorescent, Non-oxidizable Palladium and Platinum Perfluoro-phthalocyanines.

    PubMed

    Łapok, Łukasz; Obłoza, Magdalena; Gorski, Alexandr; Knyukshto, Valeri; Raichyonok, Tamara; Waluk, Jacek; Nowakowska, Maria

    2016-04-18

    New Pd(II) and Pt(II) complexes with a highly electron-deficient ligand (H2 PcF64 ) were conveniently prepared in a three-step synthesis. This is the first time that the phosphorescence of phthalocyanines with a H2 PcF64 framework has been measured. Based on these measurements, the triplet-state energies (ET ) were directly determined. Transient absorption experiments revealed broad T1 →Tn absorption spanning from ca. 350 to ca. 1000 nm and allowed determination of the triplet-state lifetimes. Removal of the Pd or Pt from the perfluoro-phthalocyanine resulted in a significant increase of the triplet lifetime for H2 PcF64 . The very efficient intersystem crossing observed for both PdPcF64 and PtPcF64 leads to residual fluorescence and suppresses the fluorescence lifetimes to less than 50 ps. The absence of Pd and Pt in the perfluoro-phthalocyanine ligand, viz. H2 PcF64 , led to a recovery of fluorescence. Cyclic voltamperometry studies pointed to complete resistance of PdPcF64 and PtPcF64 to oxidation and very strong electron affinity, which rendered these materials very good electron acceptors (n-type materials). The presence of d-orbital metals such as Pd(II) and Pt(II) in the phthalocyanine ring stabilizes their reduced forms, as indicated by the spectroelectrochemical experiments. PdPcF64 and PtPcF64 easily sensitize singlet oxygen production with very high quantum yields. Both phthalocyanines presented resistance to photodegradation in the solid state under aerobic conditions and under intense irradiation.

  2. Miscibility between differently shaped mesogens: structural and morphological study of a phthalocyanine-perylene binary system.

    PubMed

    Zucchi, Gaël; Viville, Pascal; Donnio, Bertrand; Vlad, Alexandru; Melinte, Sorin; Mondeshki, Mihail; Graf, Robert; Spiess, Hans Wolfgang; Geerts, Yves H; Lazzaroni, Roberto

    2009-04-23

    The thermotropic, structural, and morphological properties of blends of a disk-like liquid crystalline phthalocyanine derivative and a lath-shaped perylenetetracarboxidiimide mesogen derivative have been studied by combining differential scanning calorimetry, thermal polarized optical microscopy, X-ray diffraction, solid-state nuclear magnetic resonance, and atomic force microscopy. The two compounds are fully miscible for blends containing at least 60 mol % of the disk-like molecule. In such composition range, the homogeneous blends form a columnar hexagonal (Col(h)) mesophase for which the thermal stability is enhanced compared to that of the corresponding mesophase of the pure phthalocyanine. The miscible blends self-align homeotropically between two glass slides. For blends containing between 55 and 40 mol % of the disk-shaped molecule, the two components are fully miscible at high temperature but the perylene derivative forms a separate crystalline phase when the temperature is decreased. Phase separation is systematically observed in blends containing less than 40 mol % of the discotic molecule. In this case, the resulting Col(h) mesophase is less stabilized compared to the blends containing a larger amount of the phthalocyanine derivative. These phase-separated blends do not show any homeotropic alignment. AFM investigations confirm the formation of a single columnar morphology in the phthalocyanine-rich blends, consistent with the full miscibility between the two compounds. Solid-state NMR measurements on the mixed phase show the influence of the presence of the perylene molecules on the molecular dynamics of the molecules; remarkably, the presence of the host molecules improves the local order parameter in the phthalocyanine columnar phase. PMID:19301888

  3. Synthesis of asymmetric zinc(II) phthalocyanines with two different functional groups & spectroscopic properties and photodynamic activity for photodynamic therapy.

    PubMed

    Göksel, Meltem

    2016-09-15

    Zinc(II) phthalocyanine containing [2-(tert-butoxycarbonyl)amino]ethoxy and iodine groups (A and B), as well as their deprotected mono-amino and tri-iodine zinc(II) phthalocyanine (2) were obtained. This structure surrounds by substituents with functional groups. From this perspective it can be used a starting material for many reactions and applications, such as sonogashira coupling, carbodiimide coupling. An example of a first diversification reaction of this compound was obtained with conjugation of a biotin. Asymmetrically biotin conjugated and heavy atom bearing zinc(II) phthalocyanine (3) were synthesized characterized for the first time and photophysical, photochemical and photobiological properties of these phthalocyanines were compared in this study. PMID:27423301

  4. A 'two-point' bound zinc porphyrin-zinc phthalocyanine-fullerene supramolecular triad for sequential energy and electron transfer.

    PubMed

    KC, Chandra B; Ohkubo, Kei; Karr, Paul A; Fukuzumi, Shunichi; D'Souza, Francis

    2013-09-01

    A novel supramolecular triad composed of a zinc porphyrin-zinc phthalocyanine dyad and fullerenes has been assembled using a 'two-point' axial binding approach, and occurrence of efficient photoinduced energy transfer followed by electron transfer is demonstrated.

  5. Synthesis of asymmetric zinc(II) phthalocyanines with two different functional groups & spectroscopic properties and photodynamic activity for photodynamic therapy.

    PubMed

    Göksel, Meltem

    2016-09-15

    Zinc(II) phthalocyanine containing [2-(tert-butoxycarbonyl)amino]ethoxy and iodine groups (A and B), as well as their deprotected mono-amino and tri-iodine zinc(II) phthalocyanine (2) were obtained. This structure surrounds by substituents with functional groups. From this perspective it can be used a starting material for many reactions and applications, such as sonogashira coupling, carbodiimide coupling. An example of a first diversification reaction of this compound was obtained with conjugation of a biotin. Asymmetrically biotin conjugated and heavy atom bearing zinc(II) phthalocyanine (3) were synthesized characterized for the first time and photophysical, photochemical and photobiological properties of these phthalocyanines were compared in this study.

  6. Regioisomer-Free C 4h β-Tetrakis(tert-butyl)metallo-phthalocyanines: Regioselective Synthesis and Spectral Investigations.

    PubMed

    Iida, Norihito; Tanaka, Kenta; Tokunaga, Etsuko; Takahashi, Hiromi; Shibata, Norio

    2015-04-01

    Metal β-tetrakis(tert-butyl)phthalocyanines are the most commonly used phthalocyanines due to their high solubility, stability, and accessibility. They are commonly used as a mixture of four regioisomers, which arise due to the tert-butyl substituent on the β-position, and to the best of our knowledge, their regioselective synthesis has yet to be reported. Herein, the C 4h -selective synthesis of β-tetrakis(tert-butyl)metallophthalocyanines is disclosed. Using tetramerization of α-trialkylsilyl phthalonitriles with metal salts following acid-mediated desilylation, the desired metallophthalocyanines were obtained in good yields. Upon investigation of regioisomer-free zinc β-tetrakis(tert-butyl)phthalocyanine using spectroscopy, the C 4h single isomer described here was found to be distinct in the solid state to zinc β-tetrakis(tert-butyl)phthalocyanine obtained by a conventional method.

  7. Fluorescence Behaviour of an Aluminium Octacarboxy Phthalocyanine--NaYGdF4:Yb/Er Nanoparticle Conjugate.

    PubMed

    Taylor, Jessica; Litwinski, Christian; Nyokong, Tebello; Antunes, Edith

    2015-05-01

    Using a methanol assisted thermal decomposition approach, sphere shaped NaYGdF4:Yb/Er upconversion nanoparticles (UCNPs) were successfully synthesized. The chemical, spectroscopic and fluorescence properties of the UCNPs were fully characterized. Characteristic upconversion fluorescence emissions were produced by the NPs in the green, red and NIR regions and the NPs were also shown to possess paramagnetic properties. The influence of the UCNPs on the spectroscopic and fluorescence properties of an aluminium octacarboxy phthalocyanine AlOCPc was investigated. Covalent conjugation to an AlOCPc resulted in a large blue shift of the phthalocyanine's Q band, which was accompanied by a decrease in the Pc's fluorescence lifetime in DMSO. By combining the phthalocyanine and upconversion nanoparticle, we present a system capable of multimodal imaging, using both the upconversion nanoparticle's and phthalocyanine's emission, and magnetic resonance imaging (as a result of doping the upconversion nanoparticles with Gd(3+) ions). PMID:25744527

  8. Excited-State Absorption from Real-Time Time-Dependent Density Functional Theory: Optical Limiting in Zinc Phthalocyanine.

    PubMed

    Fischer, Sean A; Cramer, Christopher J; Govind, Niranjan

    2016-04-01

    Optical-limiting materials are capable of attenuating light to protect delicate equipment from high-intensity light sources. Phthalocyanines have attracted a lot of attention for optical-limiting applications due to their versatility and large nonlinear absorption. With excited-state absorption (ESA) being the primary mechanism for optical limiting behavior in phthalocyanines, the ability to tune the optical absorption of ground and excited states in phthalocyanines would allow for the development of advanced optical limiters. We recently developed a method for the calculation of ESA based on real-time time-dependent density functional theory propagation of an excited-state density. In this work, we apply the approach to zinc phthalocyanine, demonstrating the ability of our method to efficiently identify the optical limiting potential of a molecular complex.

  9. Time-of-flight study of photoinduced dynamics of copper and manganese phthalocyanine thin films on Si(111)

    NASA Astrophysics Data System (ADS)

    Ramonova, A. G.; Butkhuzi, T. G.; Abaeva, V. V.; Tvauri, I. V.; Khubezhov, S. A.; Turiev, A. M.; Tsidaeva, N. I.; Magkoev, T. T.

    2013-11-01

    Photoinduced fragmentation and desorption of species from copper phthalocyanine (CuPc) and manganese phthalocyanine 80 nm thick films deposited on Si(111) have been studied by means of atomic force microscopy and time-of-flight mass spectroscopy in an ultra-high vacuum chamber. The main fragments formed under the effect of low-fluence (1-3 mJ cm-2) nanosecond laser light with photon energies of 2.34 and 1.17 eV are the entire phthalocyanine molecule, molecular fragments, atomic Cu and Mn and a Si-substituted CuPc. The latter is presumably due to migration of the Si atom of the underlying support to the vacancy formed after photoejection of the metallic atom out of the phthalocyanine molecule. The mechanism of photofragmentation and desorption is essentially non-thermal involving the metal atom as a key factor.

  10. Folate receptor mediated targeted delivery of ricin entrapped into sterically stabilized liposomes to human epidermoid carcinoma (KB) cells: effect of monensin intercalated into folate-tagged liposomes.

    PubMed

    Tyagi, Nikhil; Ghosh, Prahlad C

    2011-07-17

    Ricin was encapsulated into various sterically stabilized liposomes having different density of folate on the surface and the cytotoxicity of ricin in these liposomes was examined in KB cells. The effect of monensin in free and various sterically stabilized liposomal forms having different density of folate on the surface on the enhancement of cytotoxicity of ricin entrapped in these liposomes was also examined. It was observed that liposomal ricin having 0.5 mol% folate-PEG on the surface exhibits maximum cytotoxicity (IC(50)=1274 ng/ml) in KB cells as compared to non-targeted liposomes (IC(50)=3274 ng/ml). Monensin either in free form (266.2-fold) or liposomal form (291.5-fold) enhances the cytotoxicity of this targeted liposomal ricin significantly. This enhancement of the cytotoxicity of ricin entrapped in folate-targeted liposomes is further enhanced to 557.7-fold by monensin when it was delivered through folate-targeted (0.5 mol% folate-PEG) liposomes. The present study has clearly demonstrated that ricin entrapped in folate-tagged-sterically stabilized liposomes in combination with monensin intercalated in folate-tagged-sterically stabilized liposomes may have potential application for the treatment of cancer cells over-expressing folate receptors on the cell surface.

  11. Thermal and photic stimuli-responsive polydiacetylene liposomes with reversible fluorescence

    NASA Astrophysics Data System (ADS)

    Yan, Xiaojuan; An, Xueqin

    2013-06-01

    A novel reversible fluorescent switch of a polydiacetylene liposome (PDA liposome) was realized by alternating heating and UV irradiation processes. The reversible fluorescence switching of the PDA liposome was mainly caused by the microstructural changes of the PDA backbone in the PDA liposomes under the alternating conditions of heating and UV irradiation.A novel reversible fluorescent switch of a polydiacetylene liposome (PDA liposome) was realized by alternating heating and UV irradiation processes. The reversible fluorescence switching of the PDA liposome was mainly caused by the microstructural changes of the PDA backbone in the PDA liposomes under the alternating conditions of heating and UV irradiation. Electronic supplementary information (ESI) available: The preparation method, cytotoxicity and biocompatibility assays and HREM images of PDA liposomes. See DOI: 10.1039/c3nr00954h

  12. Characterization of fatty acid liposome coated with low-molecular-weight chitosan.

    PubMed

    Tan, Hsiao Wei; Misran, Misni

    2012-12-01

    Preparation of chitosan-coated fatty acid liposomes is often restricted by the solubility of chitosan under basic conditions. In this experiment, the preparation of chitosan-coated oleic acid (OA) liposomes using low molecular weight (LMW) chitosan (10 and 25 kDA) was demonstrated. These selected LMW chitosans are water soluble. The coating of the chitosan layer on OA liposomes was confirmed by its microscope images and physicochemical properties, such as zeta potential and the size of the liposomes. The "peeling off" effect on the surface of chitosan-coated OA liposomes was observed in the atomic force microscope images and showed the occurrence of the chitosan layer on the surface of OA liposomes. The size of the chitosan-coated liposomes was at least 20 nm smaller than the OA liposomes, and the increase of zeta potential with the increasing amount of LMW chitosan further confirmed the presence of the surface modification of OA liposomes.

  13. Hydration of polyethylene glycol-grafted liposomes.

    PubMed Central

    Tirosh, O; Barenholz, Y; Katzhendler, J; Priev, A

    1998-01-01

    This study aimed to characterize the effect of polyethylene glycol of 2000 molecular weight (PEG2000) attached to a dialkylphosphatidic acid (dihexadecylphosphatidyl (DHP)-PEG2000) on the hydration and thermodynamic stability of lipid assemblies. Differential scanning calorimetry, densitometry, and ultrasound velocity and absorption measurements were used for thermodynamic and hydrational characterization. Using a differential scanning calorimetry technique we showed that each molecule of PEG2000 binds 136 +/- 4 molecules of water. For PEG2000 covalently attached to the lipid molecules organized in micelles, the water binding increases to 210 +/- 6 water molecules. This demonstrates that the two different structural configurations of the PEG2000, a random coil in the case of the free PEG and a brush in the case of DHP-PEG2000 micelles, differ in their hydration level. Ultrasound absorption changes in liposomes reflect mainly the heterophase fluctuations and packing defects in the lipid bilayer. The PEG-induced excess ultrasound absorption of the lipid bilayer at 7.7 MHz for PEG-lipid concentrations over 5 mol % indicates the increase in the relaxation time of the headgroup rotation due to PEG-PEG interactions. The adiabatic compressibility (calculated from ultrasound velocity and density) of the lipid bilayer of the liposome increases monotonically with PEG-lipid concentration up to approximately 7 mol %, reflecting release of water from the lipid headgroup region. Elimination of this water, induced by grafted PEG, leads to a decrease in bilayer defects and enhanced lateral packing of the phospholipid acyl chains. We assume that the dehydration of the lipid headgroup region in conjunction with the increase of the hydration of the outer layer by grafting PEG in brush configuration are responsible for increasing thermodynamic stability of the liposomes at 5-7 mol % of PEG-lipid. At higher PEG-lipid concentrations, compressibility and partial volume of the lipid phase

  14. Liposomes for targeting hepatocellular carcinoma: use of conjugated arabinogalactan as targeting ligand.

    PubMed

    Shah, Sanket M; Goel, Peeyush N; Jain, Ankitkumar S; Pathak, Pankaj O; Padhye, Sameer G; Govindarajan, Srinath; Ghosh, Sandipto S; Chaudhari, Pradip R; Gude, Rajiv P; Gopal, Vijaya; Nagarsenker, Mangal S

    2014-12-30

    Present study investigates the potential of chemically modified (Shah et al., 2013) palmitoylated arabinogalactan (PAG) in guiding liposomal delivery system and targeting asialoglycoprotein receptors (ASGPR) which are expressed in hepatocellular carcinoma (HCC). PAG was incorporated in liposomes during preparation and doxorubicin hydrochloride was actively loaded in preformed liposomes with and without PAG. The liposomal systems with or without PAG were evaluated for in vitro release, in vitro cytotoxicity, in vitro cell uptake on ASGPR(+) cells, in vivo pharmacokinetic study, in vivo biodistribution study, and in vivo efficacy study in immunocompromised mice. The particle size for all the liposomal systems was below 200 nm with a negative zeta potential. Doxorubicin loaded PAG liposomes released significantly higher amount of doxorubicin at pH 5.5 as compared to pH 7.4, providing advantage for targeted tumor therapy. Doxorubicin in PAG liposomes showed superior cytotoxicity on ASGPR(+) HepG2 cells as compared to ASGPR(-), MCF7, A549, and HT29 cells. Superior uptake of doxorubicin loaded PAG liposomes as compared to doxorubicin loaded conventional liposomes was evident in confocal microscopy studies. Higher AUC in pharmacokinetic study and higher deposition in liver was observed for PAG liposomes compared to conventional liposomes. Significantly higher tumor suppression was noted in immunocompromised mice for mice treated with PAG liposomes as compared to the conventional liposomes. Targeting ability and superior activity of PAG liposomes is established pre-clinically suggesting potential of targeted delivery system for improved treatment of HCC.

  15. Cholesterol derivatives based charged liposomes for doxorubicin delivery: preparation, in vitro and in vivo characterization.

    PubMed

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

    2012-01-01

    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.

  16. Sustained distribution of aerosolized PEGylated liposomes in epithelial lining fluids on alveolar surfaces.

    PubMed

    Kaneko, Keita; Togami, Kohei; Yamamoto, Eri; Wang, Shujun; Morimoto, Kazuhiro; Itagaki, Shirou; Chono, Sumio

    2016-10-01

    The distribution characteristics of aerosolized PEGylated liposomes in alveolar epithelial lining fluid (ELF) were examined in rats, and the ensuing mechanisms were investigated in the in vitro uptake and protein adsorption experiments. Nonmodified or PEGylated liposomes (particle size 100 nm) were aerosolized into rat lungs. PEGylated liposomes were distributed more sustainably in ELFs than nonmodified liposomes. Furthermore, the uptake of PEGylated liposomes by alveolar macrophages (AMs) was less than that of nonmodified liposomes. In further in vitro uptake experiments, nonmodified and PEGylated liposomes were opsonized with rat ELF components and then added to NR8383 cells as cultured rat AMs. The uptake of opsonized PEGylated liposomes by NR8383 cells was lower than that of opsonized nonmodified liposomes. Moreover, the protein absorption levels in opsonized PEGylated liposomes were lower than those in opsonized nonmodified liposomes. These findings suggest that sustained distributions of aerosolized PEGylated liposomes in ELFs reflect evasion of liposomal opsonization with surfactant proteins and consequent reductions in uptake by AMs. These data indicate the potential of PEGylated liposomes as aerosol-based drug delivery system that target ELF for the treatment of respiratory diseases.

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

    PubMed Central

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

    2012-01-01

    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. PMID:23227125

  18. Sustained distribution of aerosolized PEGylated liposomes in epithelial lining fluids on alveolar surfaces.

    PubMed

    Kaneko, Keita; Togami, Kohei; Yamamoto, Eri; Wang, Shujun; Morimoto, Kazuhiro; Itagaki, Shirou; Chono, Sumio

    2016-10-01

    The distribution characteristics of aerosolized PEGylated liposomes in alveolar epithelial lining fluid (ELF) were examined in rats, and the ensuing mechanisms were investigated in the in vitro uptake and protein adsorption experiments. Nonmodified or PEGylated liposomes (particle size 100 nm) were aerosolized into rat lungs. PEGylated liposomes were distributed more sustainably in ELFs than nonmodified liposomes. Furthermore, the uptake of PEGylated liposomes by alveolar macrophages (AMs) was less than that of nonmodified liposomes. In further in vitro uptake experiments, nonmodified and PEGylated liposomes were opsonized with rat ELF components and then added to NR8383 cells as cultured rat AMs. The uptake of opsonized PEGylated liposomes by NR8383 cells was lower than that of opsonized nonmodified liposomes. Moreover, the protein absorption levels in opsonized PEGylated liposomes were lower than those in opsonized nonmodified liposomes. These findings suggest that sustained distributions of aerosolized PEGylated liposomes in ELFs reflect evasion of liposomal opsonization with surfactant proteins and consequent reductions in uptake by AMs. These data indicate the potential of PEGylated liposomes as aerosol-based drug delivery system that target ELF for the treatment of respiratory diseases. PMID:27334278

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

    SciTech Connect

    Aragon-Aguilar, Hector; Ramon-Gallegos, Eva; Arenas-Huertero, Francisco Jesus; Cruz-Orea, Alfredo; Sosa-Sanchez, Jose Luis; Garcia Miranda, Maribel

    2008-08-11

    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.

  20. Photophysical and photochemical studies of a novel amphiphilic zinc phthalocyanine and its interaction with calf thymus DNA

    NASA Astrophysics Data System (ADS)

    Yuan, Linxin; Gui, Li; Wang, Yue; Zhang, Quanquan; Zhou, Lin; Wei, Shaohua

    2016-04-01

    β-tetra (aminophenoxy) sulfonic substituted zinc phthalocyanines (SNZnPc), a novel amphiphilic zinc phthalocyanine (Pc), was synthesized. The photophysical, photochemical, and photobiology properties were studied. Results indicated that the synthesized SNZnPc has good amphiphilic property and high reactive oxygen species (ROSs) generation ability. Furthermore, SNZnPc has strong affinity to calf thymus DNA (CT-DNA) through intercalation ways and can effectively cleavage CT-DNA after irradiation by light with appropriate wavelength.

  1. Electronic structure differences between H(2)-, Fe-, Co-, and Cu-phthalocyanine highly oriented thin films observed using NEXAFS spectroscopy.

    PubMed

    Willey, T M; Bagge-Hansen, M; Lee, J R I; Call, R; Landt, L; van Buuren, T; Colesniuc, C; Monton, C; Valmianski, I; Schuller, Ivan K

    2013-07-21

    Phthalocyanines, a class of macrocyclic, square planar molecules, are extensively studied as semiconductor materials for chemical sensors, dye-sensitized solar cells, and other applications. In this study, we use angular dependent near-edge x-ray absorption fine structure (NEXAFS) spectroscopy as a quantitative probe of the orientation and electronic structure of H2-, Fe-, Co-, and Cu-phthalocyanine molecular thin films. NEXAFS measurements at both the carbon and nitrogen K-edges reveal that phthalocyanine films deposited on sapphire have upright molecular orientations, while films up to 50 nm thick deposited on gold substrates contain prostrate molecules. Although great similarity is observed in the carbon and nitrogen K-edge NEXAFS spectra recorded for the films composed of prostrate molecules, the H2-phthalocyanine exhibits the cleanest angular dependence due to its purely out-of-plane π* resonances at the absorption onset. In contrast, organometallic-phthalocyanine nitrogen K-edges have a small in-plane resonance superimposed on this π* region that is due to a transition into molecular orbitals interacting with the 3dx(2)-y(2) empty state. NEXAFS spectra recorded at the metal L-edges for the prostrate films reveal dramatic variations in the angular dependence of specific resonances for the Cu-phthalocyanines compared with the Fe-, and Co-phthalocyanines. The Cu L3,2 edge exhibits a strong in-plane resonance, attributed to its b1g empty state with dx(2)-y(2) character at the Cu center. Conversely, the Fe- and Co- phthalocyanine L3,2 edges have strong out-of-plane resonances; these are attributed to transitions into not only b1g (dz(2)) but also eg states with dxz and dyz character at the metal center.

  2. Electronic structure differences between H2-, Fe-, Co-, and Cu-phthalocyanine highly oriented thin films observed using NEXAFS spectroscopy

    NASA Astrophysics Data System (ADS)

    Willey, T. M.; Bagge-Hansen, M.; Lee, J. R. I.; Call, R.; Landt, L.; van Buuren, T.; Colesniuc, C.; Monton, C.; Valmianski, I.; Schuller, Ivan K.

    2013-07-01

    Phthalocyanines, a class of macrocyclic, square planar molecules, are extensively studied as semiconductor materials for chemical sensors, dye-sensitized solar cells, and other applications. In this study, we use angular dependent near-edge x-ray absorption fine structure (NEXAFS) spectroscopy as a quantitative probe of the orientation and electronic structure of H2-, Fe-, Co-, and Cu-phthalocyanine molecular thin films. NEXAFS measurements at both the carbon and nitrogen K-edges reveal that phthalocyanine films deposited on sapphire have upright molecular orientations, while films up to 50 nm thick deposited on gold substrates contain prostrate molecules. Although great similarity is observed in the carbon and nitrogen K-edge NEXAFS spectra recorded for the films composed of prostrate molecules, the H2-phthalocyanine exhibits the cleanest angular dependence due to its purely out-of-plane π* resonances at the absorption onset. In contrast, organometallic-phthalocyanine nitrogen K-edges have a small in-plane resonance superimposed on this π* region that is due to a transition into molecular orbitals interacting with the 3dx2-y2 empty state. NEXAFS spectra recorded at the metal L-edges for the prostrate films reveal dramatic variations in the angular dependence of specific resonances for the Cu-phthalocyanines compared with the Fe-, and Co-phthalocyanines. The Cu L3,2 edge exhibits a strong in-plane resonance, attributed to its b1g empty state with dx2-y2 character at the Cu center. Conversely, the Fe- and Co- phthalocyanine L3,2 edges have strong out-of-plane resonances; these are attributed to transitions into not only b1g (dz2) but also eg states with dxz and dyz character at the metal center.

  3. Photophysical and photochemical studies of a novel amphiphilic zinc phthalocyanine and its interaction with calf thymus DNA.

    PubMed

    Yuan, Linxin; Gui, Li; Wang, Yue; Zhang, Quanquan; Zhou, Lin; Wei, Shaohua

    2016-04-01

    β-tetra (aminophenoxy) sulfonic substituted zinc phthalocyanines (SNZnPc), a novel amphiphilic zinc phthalocyanine (Pc), was synthesized. The photophysical, photochemical, and photobiology properties were studied. Results indicated that the synthesized SNZnPc has good amphiphilic property and high reactive oxygen species (ROSs) generation ability. Furthermore, SNZnPc has strong affinity to calf thymus DNA (CT-DNA) through intercalation ways and can effectively cleavage CT-DNA after irradiation by light with appropriate wavelength.

  4. Features of the spectral dependences of transmittance of organic semiconductors based on tert-butyl substituted lutetium phthalocyanine molecules

    SciTech Connect

    Belogorokhov, I. A.; Tikhonov, E. V.; Dronov, M. A.; Belogorokhova, L. I.; Ryabchikov, Yu. V.; Tomilova, L. G.; Khokhlov, D. R.

    2011-11-15

    Vibronic properties of organic semiconductors based on tert-butyl substituted phthalocyanine lutetium diphthalocyanine molecules are studied by IR and Raman spectroscopy. It is shown that substitution of several carbon atoms in initial phthalocyanine (Pc) ligands with {sup 13}C isotope atoms causes a spectral shift in the main absorption lines attributed to benzene, isoindol, and peripheral C-H groups. A comparison of spectral characteristics showed that the shift can vary from 3 to 1 cm{sup -1}.

  5. Changes in the adsorbate dipole layer with changing d-filling of the metal (II) (Co, Ni, Cu) phthalocyanines on Au(111).

    PubMed

    Xiao, Jie; Dowben, Peter A

    2009-02-01

    In combined photoemission and inverse photoemission spectroscopy studies, we observe changes in the metal phthalocyanine molecular orbital offsets with respect to the conducting gold substrate Fermi level, with the changing d-electron filling of the metal (II) (Co, Ni, Cu) phthalocyanines. The implication is that the interfacial dipole layer depends upon the choice of metal (Co, Ni, Cu) centers within the metal (II) phthalocyanines adsorbed on Au(111).

  6. Liposomes with polyribonucleotides as model of precellular systems

    NASA Technical Reports Server (NTRS)

    Baeza, Isabel; Ibanez, Miguel; Santiago, Carlos; Lazcano, Antonio; Arguello, Carlos

    1987-01-01

    Three types of liposomes were prepared under anoxic conditions: from dipalmitoyl phosphatidyl choline (DPPC), from egg yolk phosphatidyl choline (PC), and from PC with cholesterol (PC:Chol). These were used for encapsulation of poly(U) and poly(C). It was found that 36 to 70 percent of the available liposome lipids and 2 to 5 percent of the polyribonucleotides could be entrapped. An enhanced encapsulation of poly(U) and poly(C) by all three types of liposomes was observed in the presence of 0.001 to 0.01 M Zn(2+), with the effect being greatest with DPPC. The presence of 1.0 M urea inhibited the formation of PC liposomes.

  7. Antigen-specific suppression of inflammatory arthritis using liposomes.

    PubMed

    Capini, Christelle; Jaturanpinyo, Montree; Chang, Hsin-I; Mutalik, Srinivas; McNally, Alice; Street, Shayna; Steptoe, Raymond; O'Sullivan, Brendan; Davies, Nigel; Thomas, Ranjeny

    2009-03-15

    Existing therapies for rheumatoid arthritis and other autoimmune diseases are not Ag specific, which increases the likelihood of systemic toxicity. We show that egg phosphatidylcholine liposomes loaded with Ag (OVA or methylated BSA) and a lipophilic NF-kappaB inhibitor (curcumin, quercetin, or Bay11-7082) suppress preexisting immune responses in an Ag-specific manner. We injected loaded liposomes into mice primed with Ag or into mice suffering from Ag-induced inflammatory arthritis. The liposomes targeted APCs in situ, suppressing the cells' responsiveness to NF-kappaB and inducing Ag-specific FoxP3(+) regulatory T cells. This regulatory mechanism suppressed effector T cell responses and the clinical signs of full-blown Ag-induced arthritis. Thus, liposomes encapsulate Ags and NF-kappaB inhibitors stably and efficiently and could be readily adapted to deliver Ags and inhibitors for Ag-specific suppression of other autoimmune and allergic diseases.

  8. Precipitation in liposomes as a model for intracellular biomineralization.

    PubMed

    Tester, Chantel C; Joester, Derk

    2013-01-01

    Liposomes present a versatile platform to model intracellular, biologically controlled mineralization. Perhaps, most importantly, precipitation in the confinement of liposomes excludes heterogeneous nucleators that facilitate formation of the thermodynamically most stable crystalline phase in bulk. This provides access to metastable amorphous precursors even in the absence of other additives that interact strongly with the mineral and is fundamental to the capability of cells to prevent spurious nucleation and to select a specific polymorph. Herein, we summarize methods to prepare liposomes from the nanometer to micron length scale and review strategies to carry out precipitation reactions of iron oxide, calcium carbonate, and calcium phosphate in the confinement of such liposomes. In addition, we discuss methods to characterize the morphology, structure, and growth kinetics of crystalline and amorphous precipitates, with particular emphasis on in situ characterization approaches.

  9. Potential utility of liposome bupivacaine in orthopedic surgery.

    PubMed

    Lonner, Jess H; Scuderi, Giles R; Lieberman, Jay R

    2015-03-01

    Management of postsurgical analgesia is an important consideration in orthopedic procedures, including joint arthroplasty. Inadequate postsurgical analgesia is associated with increased hospital length of stay, delayed ambulation, and reduced exercise capacity. In this article, we review the potential contribution of a prolonged-release liposomal formulation of bupivacaine as part of a multimodal analgesic regimen after orthopedic surgery. Controlled studies across multiple surgical settings have demonstrated that, compared with placebo and bupivacaine HCl, liposome bupivacaine in a single administration provides postsurgical analgesia for up to 72 hours, delays use of rescue medication, and reduces postsurgical opioid consumption. Liposome bupivacaine has been well tolerated in clinical studies and has had a low rate of treatment-related adverse events. To date, there has been no signal of cardiac toxicity, chondrolysis, or delayed wound healing associated with liposome bupivacaine.

  10. [Liposomal boron delivery system for neutron capture therapy].

    PubMed

    Nakamura, Hiroyuki

    2008-02-01

    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.

  11. Atmospheric-pressure guided streamers for liposomal membrane disruption

    NASA Astrophysics Data System (ADS)

    Svarnas, P.; Matrali, S. H.; Gazeli, K.; Aleiferis, Sp.; Clément, F.; Antimisiaris, S. G.

    2012-12-01

    The potential to use liposomes (LIPs) as a cellular model in order to study interactions of cold atmospheric-pressure plasma with cells is herein investigated. Cold atmospheric-pressure plasma is formed by a dielectric-barrier discharge reactor. Large multilamellar vesicle liposomes, consisted of phosphatidylcholine and cholesterol, are prepared by the thin film hydration technique, to encapsulate a small hydrophilic dye, i.e., calcein. The plasma-induced release of calcein from liposomes is then used as a measure of liposome membrane integrity and, consequently, interaction between the cold atmospheric plasma and lipid bilayers. Physical mechanisms leading to membrane disruption are suggested, based on the plasma characterization including gas temperature calculation.

  12. Interaction of Sindbis virus with liposomal model membranes.

    PubMed Central

    Mooney, J J; Dalrymple, J M; Alving, C R; Russell, P K

    1975-01-01

    Radiolabeled Sindbis virus was found to bind to protein-free lipid model membranes (liposomes) derived from extracts of sheep erythrocytes. The virus interaction was dependent on initial pH, and the range of pH dependence (pH 6.0 to 6.8) was the same as the observed with virus-dependent hemagglutination. After the initial interaction, pH changes no longer influenced the virus binding to liposomes. Virus bound to liposomes prepared from a mixture of erythrocyte phospholipids, but the binding was greatly diminished when either cholesterol or phosphatidylethanolamine was omitted from the liposomal lipid mixture. It was concluded that phospholipids and cholesterol, in a bilayer configuration, may be sufficient for specific virus binding in the absence of membrane protein. PMID:234538

  13. Atmospheric-pressure guided streamers for liposomal membrane disruption

    SciTech Connect

    Svarnas, P.; Aleiferis, Sp.; Matrali, S. H.; Gazeli, K.; Clement, F.; Antimisiaris, S. G.

    2012-12-24

    The potential to use liposomes (LIPs) as a cellular model in order to study interactions of cold atmospheric-pressure plasma with cells is herein investigated. Cold atmospheric-pressure plasma is formed by a dielectric-barrier discharge reactor. Large multilamellar vesicle liposomes, consisted of phosphatidylcholine and cholesterol, are prepared by the thin film hydration technique, to encapsulate a small hydrophilic dye, i.e., calcein. The plasma-induced release of calcein from liposomes is then used as a measure of liposome membrane integrity and, consequently, interaction between the cold atmospheric plasma and lipid bilayers. Physical mechanisms leading to membrane disruption are suggested, based on the plasma characterization including gas temperature calculation.

  14. Bioreactor droplets from liposome-stabilized all-aqueous emulsions

    NASA Astrophysics Data System (ADS)

    Dewey, Daniel C.; Strulson, Christopher A.; Cacace, David N.; Bevilacqua, Philip C.; Keating, Christine D.

    2014-08-01

    Artificial bioreactors are desirable for in vitro biochemical studies and as protocells. A key challenge is maintaining a favourable internal environment while allowing substrate entry and product departure. We show that semipermeable, size-controlled bioreactors with aqueous, macromolecularly crowded interiors can be assembled by liposome stabilization of an all-aqueous emulsion. Dextran-rich aqueous droplets are dispersed in a continuous polyethylene glycol (PEG)-rich aqueous phase, with coalescence inhibited by adsorbed ~130-nm diameter liposomes. Fluorescence recovery after photobleaching and dynamic light scattering data indicate that the liposomes, which are PEGylated and negatively charged, remain intact at the interface for extended time. Inter-droplet repulsion provides electrostatic stabilization of the emulsion, with droplet coalescence prevented even for submonolayer interfacial coatings. RNA and DNA can enter and exit aqueous droplets by diffusion, with final concentrations dictated by partitioning. The capacity to serve as microscale bioreactors is established by demonstrating a ribozyme cleavage reaction within the liposome-coated droplets.

  15. Thrombin-Inhibiting Anticoagulant Liposomes: Development and Characterization.

    PubMed

    Endreas, Wegderes; Brüßler, Jana; Vornicescu, Doru; Keusgen, Michael; Bakowsky, Udo; Steinmetzer, Torsten

    2016-02-01

    Many peptides and peptidomimetic drugs suffer from rapid clearance in vivo; this can be reduced by increasing their size through oligomerization or covalent conjugation with polymers. As proof of principle, an alternative strategy for drug oligomerization is described, in which peptidomimetic thrombin inhibitors are incorporated into the liposome surface. For this purpose, the inhibitor moieties were covalently coupled to a palmitic acid residue through a short bifunctionalized ethylene glycol spacer. These molecules were directly added to the lipid mixture used for liposome preparation. The obtained liposomes possess strong thrombin inhibitory potency in enzyme kinetic measurements and anticoagulant activity in plasma. Their strong potency and positive ζ potential indicate that large amounts of the benzamidine-derived inhibitors are located on the surface of the liposomes. This concept should be applicable to other drug molecules that suffer from rapid elimination and allow covalent modification with a suitable fatty acid residue. PMID:26662675

  16. Acoustical properties of individual liposome-loaded microbubbles.

    PubMed

    Luan, Ying; Faez, Telli; Gelderblom, Erik; Skachkov, Ilya; Geers, Bart; Lentacker, Ine; van der Steen, Ton; Versluis, Michel; de Jong, Nico

    2012-12-01

    A comparison between phospholipid-coated microbubbles with and without liposomes attached to the microbubble surface was performed using the ultra-high-speed imaging camera (Brandaris 128). We investigated 73 liposome-loaded microbubbles (loaded microbubbles) and 41 microbubbles without liposome loading (unloaded microbubbles) with a diameter ranging from 3-10 μm at frequencies ranging from 0.6-3.8 MHz and acoustic pressures ranging from 5-100 kPa. The experimental data showed nearly the same shell elasticity for the loaded and unloaded bubbles, but the shell viscosity was higher for loaded bubbles compared with unloaded bubbles. For loaded bubbles, a higher pressure threshold for the bubble vibrations was noticed. In addition, an "expansion-only" behavior was observed for up to 69% of the investigated loaded bubbles, which mostly occurred at low acoustic pressures (≤30 kPa). Finally, fluorescence imaging showed heterogeneity of liposome distributions of the loaded bubbles.

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

    PubMed

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

    2010-12-01

    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.

  18. Comparison of conventional chemotherapy, stealth liposomes and temperature-sensitive liposomes in a mathematical model.

    PubMed

    Gasselhuber, Astrid; Dreher, Matthew R; Rattay, Frank; Wood, Bradford J; Haemmerich, Dieter

    2012-01-01

    Various liposomal drug carriers have been developed to overcome short plasma half-life and toxicity related side effects of chemotherapeutic agents. We developed a mathematical model to compare different liposome formulations of doxorubicin (DOX): conventional chemotherapy (Free-DOX), Stealth liposomes (Stealth-DOX), temperature sensitive liposomes (TSL) with intra-vascular triggered release (TSL-i), and TSL with extra-vascular triggered release (TSL-e). All formulations were administered as bolus at a dose of 9 mg/kg. For TSL, we assumed locally triggered release due to hyperthermia for 30 min. Drug concentrations were determined in systemic plasma, aggregate body tissue, cardiac tissue, tumor plasma, tumor interstitial space, and tumor cells. All compartments were assumed perfectly mixed, and represented by ordinary differential equations. Contribution of liposomal extravasation was negligible in the case of TSL-i, but was the major delivery mechanism for Stealth-DOX and for TSL-e. The dominant delivery mechanism for TSL-i was release within the tumor plasma compartment with subsequent tissue- and cell uptake of released DOX. Maximum intracellular tumor drug concentrations for Free-DOX, Stealth-DOX, TSL-i, and TSL-e were 3.4, 0.4, 100.6, and 15.9 µg/g, respectively. TSL-i and TSL-e allowed for high local tumor drug concentrations with reduced systemic exposure compared to Free-DOX. While Stealth-DOX resulted in high tumor tissue concentrations compared to Free-DOX, only a small fraction was bioavailable, resulting in little cellular uptake. Consistent with clinical data, Stealth-DOX resulted in similar tumor intracellular concentrations as Free-DOX, but with reduced systemic exposure. Optimal release time constants for maximum cellular uptake for Stealth-DOX, TSL-e, and TSL-i were 45 min, 11 min, and <3 s, respectively. Optimal release time constants were shorter for MDR cells, with ∼4 min for Stealth-DOX and for TSL-e. Tissue concentrations correlated well

  19. Substituent effects on the structure-property relationship of unsymmetrical methyloxy and methoxycarbonyl phthalocyanines: DFT and TDDFT theoretical studies.

    PubMed

    Zhang, Lijuan; Qi, Dongdong; Zhao, Luyang; Bian, Yongzhong; Li, Wenjun

    2012-05-01

    Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) calculations were carried out to simulate the molecular and electronic structures together with the electronic absorption spectra of a series of peripheral methyloxy/methoxycarbonyl substituented phthalocyanines M[Pc(β-OMe)(2n)(β-COOMe)(8-2n)] (M=2H, Zn; n=0, 1, 2, 3, and 4). Fragment charge distribution and electrostatic potential analysis indicate that the presence of electron-withdrawing and -donation groups leads to the redistribution of charges and obvious polarization effects to the unsymmetrical phthalocyanine series. Peripheral methyloxy/methoxycarbonyl groups introduced onto phthalocyanine ring were revealed to destroy the degeneracy of LUMOs, resulting in significant Q-band splitting for the unsymmetrical phthalocyanine compounds. In addition, metal-free and zinc phthalocyanine compounds display similar electronic structures and absorptions due to the almost none contribution of the zinc atom or inner hydrogens to the frontier molecular orbitals. The microscopic mechanism of the UV-Vis spectra has been clarified on the basis of multi-band photon-induced electron transference. These theoretical studies would be helpful for the molecular design of novel unsymmetrical phthalocyanines.

  20. Effects of central metal on electronic structure, magnetic properties, infrared and Raman spectra of double-decker phthalocyanine

    NASA Astrophysics Data System (ADS)

    Suzuki, Atsushi; Oku, Takeo

    2016-09-01

    The effects of the central metal in double-decker metal phthalocyanine on the electronic structure, magnetic properties, and infrared and Raman spectra of the complex were investigated. Electron density distributions were delocalized on the phthalocyanine rings. The narrow energy gap and infrared peaks observed in the ultra-violet-visible-near infrared spectra of the systems were attributed to phthalocyanine ring-ring interactions the between overlapping π-orbitals on each ring. The chemical shift behavior of the phthalocyanine rings was separated by the deformation of their structure owing to nuclear magnetic interaction of the nuclear quadrupole interaction as determined by the electronic field gradient and asymmetric parameters. The magnetic parameters of principle g-tensors were dependent on the perturbation of the crystal field by the hybridization of the d-spin in the central metal conjugated with nitrogen ligands. In the case of the vanadyl system, the IR vibration modes were shifted by the soft vibration mode for resolving the symmetrical structure. Inactive Raman vibration modes arose from no-polarization on the phthalocyanine rings. Double-decker metal phthalocyanines have great advantages for the control of the magnetic mechanism for quantum spin entanglement in the relaxation process.

  1. Interaction of isopropylthioxanthone with phospholipid liposomes.

    PubMed

    Momo, Federico; Fabris, Sabrina; Stevanato, Roberto

    2007-04-01

    Isopropylthioxanthone (ITX) is a highly lipophilic molecule which can be released in foods and beverages from the packages, where it is present as photoinitiator of inks in printing processes. Recently it was found in babies milk, and its toxicity cannot be excluded. The structure of the molecule suggests a possible strong interaction with the lipid moiety of biological membranes, and this is the first study of its effects on phospholipid organization, using differential scanning calorimetry (DSC) and spin labelling techniques. The data obtained with multilamellar liposomes of saturated phospholipids of different length, with and without cholesterol, point out that the molecule changes the lipid structure; in particular, in the gel state, behaving like a disordering agent it increases the mobility of the bilayer, while, in the fluid state, tends to rigidify the membrane, in a cholesterol like way. This behavior supports the hypothesis that ITX experiences a relocation process when the lipid matrix passes from the gel to the fluid state.

  2. Interaction of curcumin with lipid monolayers and liposomal bilayers.

    PubMed

    Karewicz, Anna; Bielska, Dorota; Gzyl-Malcher, Barbara; Kepczynski, Mariusz; Lach, Radosław; Nowakowska, Maria

    2011-11-01

    Curcumin shows huge potential as an anticancer and anti-inflammatory agent. However, to achieve a satisfactory bioavailability and stability of this compound, its liposomal form is preferable. Our detailed studies on the curcumin interaction with lipid membranes are aimed to obtain better understanding of the mechanism and eventually to improve the efficiency of curcumin delivery to cells. Egg yolk phosphatidylcholine (EYPC) one-component monolayers and bilayers, as well as mixed systems containing additionally dihexadecyl phosphate (DHP) and cholesterol, were studied. Curcumin binding constant to EYPC liposomes was determined based on two different methods: UV/Vis absorption and fluorescence measurements to be 4.26×10(4)M(-1) and 3.79×10(4)M(-1), respectively. The fluorescence quenching experiment revealed that curcumin locates in the hydrophobic region of EYPC liposomal bilayer. It was shown that curcumin impacts the size and stability of the liposomal carriers significantly. Loaded into the EYPC/DPH/cholesterol liposomal bilayer curcumin stabilizes the system proportionally to its content, while the EYPC/DPH system is destabilized upon drug loading. The three-component lipid composition of the liposome seems to be the most promising system for curcumin delivery. An interaction of free and liposomal curcumin with EYPC and mixed monolayers was also studied using Langmuir balance measurements. Monolayer systems were treated as a simple model of cell membrane. Condensing effect of curcumin on EYPC and EYPC/DHP monolayers and loosening influence on EYPC/DHP/chol ones were observed. It was also demonstrated that curcumin-loaded EYPC liposomes are more stable upon interaction with the model lipid membrane than the unloaded ones.

  3. Hyaluronic acid-coated liposomes for active targeting of gemcitabine.

    PubMed

    Arpicco, Silvia; Lerda, Carlotta; Dalla Pozza, Elisa; Costanzo, Chiara; Tsapis, Nicolas; Stella, Barbara; Donadelli, Massimo; Dando, Ilaria; Fattal, Elias; Cattel, Luigi; Palmieri, Marta

    2013-11-01

    The aim of this work was the preparation, characterization, and preliminary evaluation of the targeting ability toward pancreatic adenocarcinoma cells of liposomes containing the gemcitabine lipophilic prodrug [4-(N)-lauroyl-gemcitabine, C12GEM]. Hyaluronic acid (HA) was selected as targeting agent since it is biodegradable, biocompatible, and can be chemically modified and its cell surface receptor CD44 is overexpressed on various tumors. For this purpose, conjugates between a phospholipid, the 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE), and HA of two different low molecular weights 4800 Da (12 disaccharidic units) and 12,000 Da (32 disaccharidic units), were prepared, characterized, and introduced in the liposomes during the preparation. Different liposomal formulations were prepared and their characteristics were analyzed: size, Z potential, and TEM analyses underline a difference in the HA-liposomes from the non-HA ones. In order to better understand the HA-liposome cellular localization and to evaluate their interaction with CD44 receptor, confocal microscopy studies were performed. The results demonstrate that HA facilitates the recognition of liposomes by MiaPaCa2 cells (CD44(+)) and that the uptake increases with increase in the polymer molecular weight. Finally, the cytotoxicity of the different preparations was evaluated and data show that incorporation of C12GEM increases their cytotoxic activity and that HA-liposomes inhibit cell growth more than plain liposomes. Altogether, the results demonstrate the specificity of C12GEM targeting toward CD44-overexpressing pancreatic adenocarcinoma cell line using HA as a ligand.

  4. Hyaluronic acid-coated liposomes for active targeting of gemcitabine.

    PubMed

    Arpicco, Silvia; Lerda, Carlotta; Dalla Pozza, Elisa; Costanzo, Chiara; Tsapis, Nicolas; Stella, Barbara; Donadelli, Massimo; Dando, Ilaria; Fattal, Elias; Cattel, Luigi; Palmieri, Marta

    2013-11-01

    The aim of this work was the preparation, characterization, and preliminary evaluation of the targeting ability toward pancreatic adenocarcinoma cells of liposomes containing the gemcitabine lipophilic prodrug [4-(N)-lauroyl-gemcitabine, C12GEM]. Hyaluronic acid (HA) was selected as targeting agent since it is biodegradable, biocompatible, and can be chemically modified and its cell surface receptor CD44 is overexpressed on various tumors. For this purpose, conjugates between a phospholipid, the 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE), and HA of two different low molecular weights 4800 Da (12 disaccharidic units) and 12,000 Da (32 disaccharidic units), were prepared, characterized, and introduced in the liposomes during the preparation. Different liposomal formulations were prepared and their characteristics were analyzed: size, Z potential, and TEM analyses underline a difference in the HA-liposomes from the non-HA ones. In order to better understand the HA-liposome cellular localization and to evaluate their interaction with CD44 receptor, confocal microscopy studies were performed. The results demonstrate that HA facilitates the recognition of liposomes by MiaPaCa2 cells (CD44(+)) and that the uptake increases with increase in the polymer molecular weight. Finally, the cytotoxicity of the different preparations was evaluated and data show that incorporation of C12GEM increases their cytotoxic activity and that HA-liposomes inhibit cell growth more than plain liposomes. Altogether, the results demonstrate the specificity of C12GEM targeting toward CD44-overexpressing pancreatic adenocarcinoma cell line using HA as a ligand. PMID:23791684

  5. Liposomes as nanocarriers for anti-HIV therapy.

    PubMed

    Chopra, Shruti; Venkatesan, Natarajan; Betageri, Guru V

    2013-10-01

    Globally, in the last three decades of medical research, the use of liposomes as carrier for anti-HIV/AIDS drugs is gaining prominence. These potential anti-HIV nanocarriers are concentric lipid bilayers which can be fabricated to protect molecules and to target the drugs to specific sites, which is the reason behind their popularity in the antiretroviral drug delivery. The development of an effective drug delivery system such as liposomes presents an opportunity to circumvent the many challenges associated with antiretroviral drug therapy. The physiochemical properties of liposomes such as size, charge, and lipid composition significantly affect the liposomal efficiency. These nanocarriers offer advantages such as drug loading both in aqueous region and within the bilayer of the vesicles, act as solubilizing agents, protect drug from degradation in the body, allow modification of the pharmacokinetic and tissue distribution patterns of the drug, provide drug targeting, and have low immunogenicity, biocompatibility, and cell specificity. Different types of liposome-based delivery systems, such as cationic, anionic, sterically stabilized, and immunoliposomes, have been studied for the anti-HIV/AIDS drug delivery. Liposomes, however, face challenges with regard to their use in antiretroviral drug delivery such as limited hydrophilic drug-loading capacity, issues related to physical and biologic stability, poor scale-up, cost, short shelf life, and toxicity. Numerous patented strategies have been granted in the USA and around the world related to these anti-HIV nanocarriers. In the present article, we have discussed the general physiological aspects of the HIV infection, relevance of the nanocarrier, liposomes, in the treatment of this disease and some recently awarded US patents and patent applications of these liposomal delivery systems for anti-HIV drugs.

  6. Preparation and characterization of taxane-containing liposomes.

    PubMed

    Straubinger, Robert M; Balasubramanian, Sathyamangalam V

    2005-01-01

    Drug carriers such as liposomes provide a means to alter the biodisposition of drugs and to achieve concentration-time exposure profiles in tissue or tumor that are not readily accomplished with free drug. These changes in biodisposition can improve treatment efficacy. For hydrophobic drugs, incorporation in liposome carriers can increase drug solubility markedly. The taxanes paclitaxel (taxol) and docetaxel (Taxotere) are members of one of the most important new classes of oncology drugs. However, their poor solubility presents pharmaceutical challenges, and emerging data suggest that specific tissue exposure profiles, such as low drug concentrations for extended times, can enhance beneficial antitumor mechanisms. Incorporation of the taxanes into liposomes eliminates not only the toxic effects of cosolvents required to administer these drugs clinically but also increases drug efficacy in animal tumor models, usually through a reduction in dose-limiting tissue toxicities. Although the taxanes are poorly water soluble, the preparation of physically stabile taxane-liposome formulations requires the balancing of three factors: (1) the drug:lipid ratio, (2) the liposome composition, and (3) the duration of storage in aqueous media. Biophysical evaluation of formulation characteristics, principally using circular dichroism (CD) and differential scanning calorimetry (DSC), can provide the information necessary to develop stable taxane-liposome formulations. These techniques provide information on drug-drug and drug-lipid interactions that underlie the events that lead to taxane formulation instability. Owing to the unusually low solubility of the taxanes, special consideration is necessary to devise methods for resolving drug-containing liposomes from released or precipitated drug to obtain reliable estimates of drug incorporation and retention in liposomes.

  7. Ultrasonic Activation of Thermally Sensitive Liposomes

    NASA Astrophysics Data System (ADS)

    Mylonopouloua, Eleonora; Arvanitisa, Costas D.; Bazan-Peregrinoa, Miriam; Arora, Manish; Coussios, Constantin C.

    2010-03-01

    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.

  8. Interaction of fluoxetine with phosphatidylcholine liposomes.

    PubMed

    Momo, Federico; Fabris, Sabrina; Stevanato, Roberto

    2005-10-22

    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 liposomes of DMPC (C14:0) are broadened and shifted towards lower temperatures at increasing dopant concentrations and, with less than 10% fluoxetine, any detectable transition is destroyed. The broadened profiles and the lowered transition temperatures demonstrate that both the size and the packing of the cooperative units undergoing the transition are modified by fluoxetine, leading to a looser and more flexible bilayer. No phase separation was observed. The effects of fluoxetine on the thermotropic phase behaviour of DPPC (C16:0) and, even more, of DSPC (C18:0) are different from that of DMPC. In fact, in the former cases, two peaks appeared at increasing dopant concentrations, suggesting the occurrence of a phase separation phenomenon, which is a sign of a binding of fluoxetine in the phosphate region. In cholesterol containing membranes, fluoxetine, even at low concentrations, leads to a general corruption of the membrane, both in terms of packing and cooperativity, and the formation of any new phase is no longer observable. EPR spectra reflect the disordered motion of acyl chains in the bilayer. It was found that fluoxetine lowers the order of the lipid chains mainly in correspondence of the fifth carbon position of SASL, indicating a possible accumulation near the interfacial region.

  9. Rapid diagnostic imaging of cancer using radiolabeled liposomes.

    PubMed

    Ogihara-Umeda, I; Sasaki, T; Toyama, H; Oda, K; Senda, M; Nishigori, H

    1997-01-01

    A novel tumor diagnostic imaging method was developed that allows tumor localization soon after administration of radiolabeled liposomes. Although previous studies showed that radiolabeled liposomes can reach various tumors in a short time, their blood clearance is slow, and the high blood background hinders early imaging. Therefore, we attempted to remove actively the liposomes from the circulation using the strong affinity between avidin and biotin. Liposomes that had biotin bound to their surface and were labeled with 111In, 67Ga, or 99mTc were administered to mice bearing sarcoma 180, followed by administration of avidin 2 or 4 h later. Avidin initiated liposomal aggregation, resulting in their rapid removal by the reticuloendothelial system. Consequently, their blood level was markedly reduced without any changes in tumor levels. The tumor-to-blood ratio reached about 13 at only 2.5 h after administration of 99mTc-labeled liposomes, versus 1.0 or less without postadministration of avidin. Increased liver accumulation was also observed, but it decreased gradually with time.

  10. Insertion of a glycosylphosphatidylinositol-anchored enzyme into liposomes.

    PubMed

    Ronzon, F; Morandat, S; Roux, B; Bortolato, M

    2004-02-01

    Incorporation of alkaline phosphatase (AP), a glycosylphosphatidylinositol (GPI)-anchored protein, into liposomes containing detergent, followed by detergent removal with hydrophobic resin was performed. Incorporation media were collected during different steps of detergent removal and were analyzed by flotation in sucrose gradient. The presence of protein was checked by measuring enzymatic activity, while the presence of (3)H-radio-labelled liposomes was followed by determination of the radioactivity. The incorporation yield of the protein into liposomes increased with incubation time in presence of hydrophobic resin. Protein was also incorporated at different protein/lipid ratios. At the highest protein lipid ratio, our data showed that 260 molecules of GPI-linked AP (AP-GPI) could be associated with one liposome, corresponding to 65% vesicle coverage. Finally, observations by electron cryomicroscopy indicated (i) that the protein seemed exclusively associated with the lipid bilayer via the GPI-anchor, as shown by the distance-about 2.5 nm-between the protein core and the liposome membrane; (ii) that the AP-GPI distribution was heterogeneous on the liposome surface, forming clusters of protein.

  11. The antimicrobial activity of liposomal lauric acids against Propionibacterium acnes.

    PubMed

    Yang, Darren; Pornpattananangkul, Dissaya; Nakatsuji, Teruaki; Chan, Michael; Carson, Dennis; Huang, Chun-Ming; Zhang, Liangfang

    2009-10-01

    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 was 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. PMID:19665786

  12. Peptide Anchor for Folate-Targeted Liposomal Delivery.

    PubMed

    Nogueira, Eugénia; Mangialavori, Irene C; Loureiro, Ana; Azoia, Nuno G; Sárria, Marisa P; Nogueira, Patrícia; Freitas, Jaime; Härmark, Johan; Shimanovich, Ulyana; Rollett, Alexandra; Lacroix, Ghislaine; Bernardes, Gonçalo J L; Guebitz, Georg; Hebert, Hans; Moreira, Alexandra; Carmo, Alexandre M; Rossi, Juan Pablo F C; Gomes, Andreia C; Preto, Ana; Cavaco-Paulo, Artur

    2015-09-14

    Specific folate receptors are abundantly overexpressed in chronically activated macrophages and in most cancer cells. Directed folate receptor targeting using liposomes is usually achieved using folate linked to a phospholipid or cholesterol anchor. This link is formed using a large spacer like polyethylene glycol. Here, we report an innovative strategy for targeted liposome delivery that uses a hydrophobic fragment of surfactant protein D linked to folate. Our proposed spacer is a small 4 amino acid residue linker. The peptide conjugate inserts deeply into the lipid bilayer without affecting liposomal integrity, with high stability and specificity. To compare the drug delivery potential of both liposomal targeting systems, we encapsulated the nuclear dye Hoechst 34580. The eventual increase in blue fluorescence would only be detectable upon liposome disruption, leading to specific binding of this dye to DNA. Our delivery system was proven to be more efficient (2-fold) in Caco-2 cells than classic systems where the folate moiety is linked to liposomes by polyethylene glycol.

  13. Pharmacokinetics and in vivo activity of liposome-encapsulated gentamicin.

    PubMed Central

    Swenson, C E; Stewart, K A; Hammett, J L; Fitzsimmons, W E; Ginsberg, R S

    1990-01-01

    Gentamicin sulfate was encapsulated in liposomes composed solely of egg phosphatidylcholine and administered via intravenous injection to rats and mice. The total gentamicin activity (regardless of whether it was free or liposome associated) in serum and selected tissues was determined for 24 h (serum) or up to 15 weeks (tissues) by using a microbiological assay. The mean half-lives in serum of a single 20-mg/kg dose of free (nonencapsulated) gentamicin in mice and rats were estimated to be 1.0 and 0.6 h, respectively, whereas a similar dose of encapsulated drug had apparent mean half-lives of 3.8 h in mice and 4.0 h in rats. In both species, the apparent half-life in serum of the liposomal formulation increased as the dose increased. Liposome encapsulation resulted in higher and more prolonged activity in organs rich in reticuloendothelial cells (especially spleen and liver). In acute septicemia infections in mice, the liposomal formulation showed enhanced prophylactic activity (as determined by calculation of the 50% protective dose). In a model of murine salmonellosis, liposomal gentamicin greatly enhanced survival when given as a single dose (10 mg/kg) at 1 or 2 days after infection as well as up to 7 days before infection. PMID:2183715

  14. Development of a liposomal formulation of the natural flavonoid fisetin.

    PubMed

    Mignet, Nathalie; Seguin, Johanne; Ramos Romano, Miriam; Brullé, Laura; Touil, Yasmine S; Scherman, Daniel; Bessodes, Michel; Chabot, Guy G

    2012-02-14

    The natural flavonoid fisetin (3,3',4',7-tetrahydroxyflavone) has been shown to possess antiangiogenic and anticancer properties. Because of the limited water solubility of fisetin, our aim was to design and optimize a liposomal formulation that could facilitate its in vivo administration, taking into account the availability and cost of the various components. Several methods were evaluated such as probe sonication, homogeneization, film hydration and lipid cake formation. A selection of lipid and lipid-PEG was also performed via their incorporation in different formulations based on the size of the liposomes, their polydispersity index (PDI) and the fisetin encapsulation yield. An optimal liposomal formulation was developed with P90G and DODA-GLY-PEG2000, possessing a diameter in the nanometer scale (175nm), a high homogeneity (PDI 0.12) and a high fisetin encapsulation (73%). Fisetin liposomes were stable over 59 days for their particle diameter and still retained 80% of their original fisetin content on day 32. Moreover, liposomal fisetin retained the cytotoxicity and typical morphological effect of free fisetin in different tumour and endothelial cell lines. In conclusion, based on its physico-chemical properties and retention of fisetin biological effects, the developed liposomal fisetin preparation is therefore suitable for in vivo administration.

  15. Improved photodynamic efficacy of Zn(II) phthalocyanines via glycerol substitution.

    PubMed

    Chin, Yunni; Lim, Siang Hui; Zorlu, Yunus; Ahsen, Vefa; Kiew, Lik Voon; Chung, Lip Yong; Dumoulin, Fabienne; Lee, Hong Boon

    2014-01-01

    Phthalocyanines are excellent photosensitizers for photodynamic therapy as they have strong absorbance in the near infra-red region which is most relevant for in vivo activation in deeper tissular regions. However, most phthalocyanines present two major challenges, ie, a strong tendency to aggregate and low water-solubility, limiting their effective usage clinically. In the present study, we evaluated the potential enhancement capability of glycerol substitution on the photodynamic properties of zinc (II) phthalocyanines (ZnPc). Three glycerol substituted ZnPc, 1-3, (tetra peripherally, tetra non-peripherally and mono iodinated tri non-peripherally respectively) were evaluated in terms of their spectroscopic properties, rate of singlet oxygen generation, partition coefficient (log P), intracellular uptake, photo-induced cytotoxicity and vascular occlusion efficiency. Tetrasulfonated ZnPc (ZnPcS4) was included as a reference compound. Here, we showed that 1-3 exhibited 10-100 nm red-shifted absorption peaks with higher molar absorptivity, and at least two-fold greater singlet oxygen generation rates compared to ZnPcS4. Meanwhile, phthalocyanines 1 and 2 showed more hydrophilic log P values than 3 consistent with the number of glycerol attachments but 3 was most readily taken up by cells compared to the rest. Both phthalocyanines 2 and 3 exhibited potent phototoxicity against MCF-7, HCT-116 and HSC-2 cancer cell-lines with IC50 ranging 2.8-3.2 µM and 0.04-0.06 µM respectively, while 1 and ZnPcS4 (up to 100 µM) failed to yield determinable IC50 values. In terms of vascular occlusion efficiency, phthalocyanine 3 showed better effects than 2 by causing total occlusion of vessels with diameter <70 µm of the chorioallantoic membrane. Meanwhile, no detectable vascular occlusion was observed for ZnPcS4 with treatment under similar experimental conditions. These findings provide evidence that glycerol substitution, in particular in structures 2 and 3, is able to improve

  16. Hybrid ZnO/phthalocyanine photovoltaic device with highly resistive ZnO intermediate layer.

    PubMed

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

    2013-10-01

    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) Ω 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).

  17. Laser-induced release of liposome-encapsulated dye to monitor tissue temperature: study of different liposome compositions

    NASA Astrophysics Data System (ADS)

    Desmettre, Thomas; Mordon, Serge R.; Devoisselle, Jean-Marie; Soulie-Begu, Sylvie

    1995-01-01

    This study aimed to evaluate the interest of several liposome compositions (DPPC, DSPC, DPPA) to control specific ranges of temperature and to assess the possible use of temperature sensitive liposomes in an established model such as the liver as a new approach to monitor tissue temperature under laser irradiation. Temperature sensitive liposomes (DPPC or DSPC or DPPA) loaded with carboxy-fluorescein were injected to Wistar rats. The liver was exposed and irradiated with a 100 W Nd:YAG laser (single pulse mode, pulses ranging from 100 to 260 ms, spot diameter: 4 mm) to avoid direct absorption by the dye entrapped in the liposomes. The temperature was measured with an infrared camera during laser irradiation. The animals were then sacrificed and the liver was surgically removed. Immediately after, the fluorescence was measured -- ex vivo -- with a fluorescent imaging system. We were not able to prepare stable high transition temperature liposomes (DPPE). Concerning DPPC, the mechanism of dye release at the basal temperature led to a complete leakage of the dye in less than 5 minutes. Only background fluorescence was observed but no specific response due to laser irradiation. Nevertheless the results obtained using DSPC liposomes meet to a large extent our requirements since a useful monitoring of temperature is feasible from 42 degree(s)C to 62 degree(s)C. In fact the critical temperature of most tissues varies from 53 degree(s)C to 58 degree(s)C.

  18. Silica-based monolithic capillary columns modified by liposomes for characterization of analyte-liposome interactions by capillary liquid chromatography.

    PubMed

    Moravcová, Dana; Planeta, Josef; Wiedmer, Susanne K

    2013-11-22

    This study introduces a silica-based monolith in a capillary format (0.1 mm × 100 mm) as a support for immobilization of liposomes and its characterization in immobilized liposome chromatography. Silica-based monolithic capillary columns prepared by acidic hydrolysis of tetramethoxysilane in the presence of polyethylene glycol and urea were modified by (3-aminopropyl)trimethoxysilane, whereby amino groups were introduced to the monolithic surface. These groups undergo reaction with glutaraldehyde to form an iminoaldehyde, allowing covalent binding of pre-formed liposomes containing primary amino groups. Two types of phospholipid vesicles were used for column modification; these were 2-oleoyl-1-palmitoyl-sn-glycero-3-phosphatidyl choline with and without 1,2-diacyl-sn-glycero-3-phospho-L-serine. The prepared columns were evaluated under isocratic separation conditions employing 20mM phosphate buffer at pH 7.4 as a mobile phase and a set of unrelated drugs as model analytes. The liposome layer on the synthesized columns significantly changed the column selectivity compared to the aminopropylsilylated monolithic stationary phase. Monolithic columns modified by liposomes were stable under the separation conditions, which proved the applicability of the suggested preparation procedure for the synthesis of capillary columns dedicated to study analyte-liposome interactions. The column efficiency originating from the silica monolith was preserved and reached, e.g., more than 120,000 theoretical plates/m for caffeine as a solute. PMID:23978749

  19. Liposome Delivery Systems for Inhalation: A Critical Review Highlighting Formulation Issues and Anticancer Applications.

    PubMed

    Rudokas, Mindaugas; Najlah, Mohammad; Alhnan, Mohamed Albed; Elhissi, Abdelbary

    2016-01-01

    This is a critical review on research conducted in the field of pulmonary delivery of liposomes. Issues relating to the mechanism of nebulisation and liposome composition were appraised and correlated with literature reports of liposome formulations used in clinical trials to understand the role of liposome size and composition on therapeutic outcome. A major highlight was liposome inhalation for the treatment of lung cancers. Many in vivo studies that explored the potential of liposomes as anticancer carrier systems were evaluated, including animal studies and clinical trials. Liposomes can entrap anticancer drugs and localise their action in the lung following pulmonary delivery. The safety of inhaled liposomes incorporating anticancer drugs depends on the anticancer agent used and the amount of drug delivered to the target cancer in the lung. The difficulty of efficient targeting of liposomal anticancer aerosols to the cancerous tissues within the lung may result in low doses reaching the target site. Overall, following the success of liposomes as inhalable carriers in the treatment of lung infections, it is expected that more focus from research and development will be given to designing inhalable liposome carriers for the treatment of other lung diseases, including pulmonary cancers. The successful development of anticancer liposomes for inhalation may depend on the future development of effective aerosolisation devices and better targeted liposomes to maximise the benefit of therapy and reduce the potential for local and systemic adverse effects.

  20. Stealth liposomes: review of the basic science, rationale, and clinical applications, existing and potential.

    PubMed

    Immordino, Maria Laura; Dosio, Franco; Cattel, Luigi

    2006-01-01

    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.

  1. Effects of liposome size on penetration of dl-tocopherol acetate into skin.

    PubMed

    Natsuki, R; Morita, Y; Osawa, S; Takeda, Y

    1996-05-01

    Liposomes were prepared from hydrogenated lecithin (H-PC) by sonication (S) or injection (I) of H-PC dissolved in ethanol containing dl-tocopherol acetate (VEA). The effects of liposomes on the dermal absorption of VEA were studied. The particle diameter of S-liposomes was smaller than that of I-liposomes. The penetration of liposomal H-PC into the skin was much higher for S-liposomes than for I-liposomes 30 min after application to the arms of healthy human volunteers and also to hairless rat back skin. The penetration of 14C-VEA into hairless rat back skin was higher from the liposomes than from free VEA, and the 14C-VEA penetration was higher from S-liposomes than from I-liposomes. 3H-Dipalmitoylphosphatidylcholine and 14C-VEA, which had been entrapped in liposomes, were not detected in plasma. H-PC inhibited the peroxidation of skin lipids. H-PC enhanced the penetration of VEA into the skin, but the degree of enhancement depended on the size of the liposomes, indicating that this liposomal characteristic was an important factor in dermal absorption and/or penetration.

  2. Topical liposomal gel of tretinoin for the treatment of acne: research and clinical implications.

    PubMed

    Patel, V B; Misra, A; Marfatia, Y S

    2000-01-01

    An attempt was made to pharmaceutically develop a topical liposomal tretinoin (TRE) gel and clinically evaluate the developed formulation for the treatment of acne in patients. Liposomes of TRE were prepared using the lipid film hydration technique and the entrapment efficiency of TRE in liposomes was optimized to 79.96%. The drug retention in liposomes and in liposomal TRE gel (Carbopol 934 gel base) studied at three storage conditions indicated maximum drug retention at refrigeration temperature. For liposomal TRE gel, reduced drug leakage was observed as compared to that of liposomes at all three storage conditions. Diffusion studies of plain TRE gel and liposomal TRE gel suggested prolongation (3.4 times reduction in flux value) of drug diffusion and almost two-fold increase in skin drug retention after liposomal encapsulation of drug. A comparative double-blind clinical study of the developed liposomal TRE gel, carried out on 30 acne patients over a period of 3 months, demonstrated significant enhancement (about 1.5-fold) in drug efficacy. More remarkable improvement was observed in the treatment of comedones, where the mean percent reduction in lesions increased from 62.36% for plain TRE gel to 94.17% for liposomal TRE gel. Erythema and irritation associated with the use of plain TRE gel was reduced considerably with the use of liposomal TRE gel. The findings of this investigation therefore underscore potential utility of commercialization of liposomal TRE gel in the treatment of acne. PMID:11109245

  3. The combined effect of encapsulating curcumin and C6 ceramide in liposomal nanoparticles against osteosarcoma.

    PubMed

    Dhule, Santosh S; Penfornis, Patrice; He, Jibao; Harris, Michael R; Terry, Treniece; John, Vijay; Pochampally, Radhika

    2014-02-01

    This study examines the antitumor potential of curcumin and C6 ceramide (C6) against osteosarcoma (OS) cell lines when both are encapsulated in the bilayer of liposomal nanoparticles. Three liposomal formulations were prepared: curcumin liposomes, C6 liposomes and C6-curcumin liposomes. Curcumin in combination with C6 showed 1.5 times enhanced cytotoxic effect in the case of MG-63 and KHOS OS cell lines, in comparison with curcumin liposomes alone. Importantly, C6-curcumin liposomes were found to be less toxic on untransformed primary human cells (human mesenchymal stem cells) in comparison to OS cell lines. In addition, cell cycle assays on a KHOS cell line after treatment revealed that curcumin only liposomes induced G2/M arrest by upregulation of cyclin B1, while C6 only liposomes induced G1 arrest by downregulation of cyclin D1. C6-curcumin liposomes induced G2/M arrest and showed a combined effect in the expression levels of cyclin D1 and cyclin B1. The efficiency of the preparations was tested in vivo using a human osteosarcoma xenograft assay. Using pegylated liposomes to increase the plasma half-life and tagging with folate (FA) for targeted delivery in vivo, a significant reduction in tumor size was observed with C6-curcumin-FA liposomes. The encapsulation of two water insoluble drugs, curcumin and C6, in the lipid bilayer of liposomes enhances the cytotoxic effect and validates the potential of combined drug therapy.

  4. 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

    Botosoa, Eliot. P.; Maillasson, Mike; Mougin-Degraef, Marie; Remaud-Le Saëc, Patricia; Gestin, Jean-François; Jacques, Yannick; Barbet, Jacques; Faivre-Chauvet, Alain

    2011-01-01

    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. PMID:21490749

  5. Liposome-mediated DNA immunisation via the subcutaneous route.

    PubMed

    Perrie, Y; McNeil, S; Vangala, A

    2003-01-01

    Compared to naked DNA immunisation, entrapment of plasmid-based DNA vaccines into liposomes by the dehydration-rehydration method has shown to enhance both humoural and cell-mediated immune responses to encoded antigens administered by a variety of routes. In this paper, we have investigated the application of liposome-entrapped DNA and their cationic lipid composition on such potency after subcutaneous immunisation. Plasmid pI.18Sfi/NP containing the nucleoprotein (NP) gene of A/Sichuan/2/87 (H3N2) influenza virus in the pI.18 expression vector was incorporated by the dehydration-rehydration method into liposomes composed of 16 micromol egg phosphatidylcholine (PC), 8 micromoles dioleoyl phosphatidylethanolamine (DOPE) or cholesterol (Chol) and either the cationic lipid 1,2-diodeoyl-3-(trimethylammonium) propane (DOTAP) or cholesteryl 3-N-(dimethyl amino ethyl) carbamate (DC-Chol). This method, entailing mixing of small unilamellar vesicles (SUV) with DNA, followed by dehydration and rehydration, yielded incorporation values of 90-94% of the DNA used. Mixing or rehydration of preformed cationic liposomes with 100 microg plasmid DNA also led to similarly high complexation values (92-94%). In an attempt to establish differences in the nature of DNA association with these various liposome preparations their physico-chemical characteristics were investigated. Studies on vesicle size, zeta potential and gel electrophoresis in the presence of the anion sodium dodecyl sulphate (SDS) indicate that, under the conditions employed, formulation of liposomal DNA by the dehydration-rehydration generated submicron size liposomes incorporating most of the DNA in a manner that prevents DNA displacement through anion competition. The bilayer composition of these dehydration-rehydration vesicles (DRV(DNA)) can also further influence these physico-chemical characteristics with the presence of DOPE within the liposome bilayer resulting in a reduced vesicle zeta potential. Subcutaneous

  6. Apoptosis induction by aluminum phthalocyanine tetrasulfonate-based sonodynamic therapy in HL-60 cells

    NASA Astrophysics Data System (ADS)

    Iwase, Yumiko; Yumita, Nagahiko; Nishi, Koji; Kuwahara, Hiroyuki; Fukai, Toshio; Ikeda, Toshihiko; Chen, Fu-shih; Momose, Yasunori; Umemura, Shin-ichiro

    2015-07-01

    The present study aims to investigate sonodynamically-induced apoptosis using the phthalocyanine, chloroaluminum phthalocyanine tetrasulfonate (AlPcTS). HL-60 cells were exposed to ultrasound for up to 3 min in the absence and presence of AlPcTS. Apoptosis was analyzed by cell morphology, DNA fragmentation, and caspase-3 activity. Electron spin resonance was used to measure reactive oxygen species. The number of apoptotic cells showing membrane blebbing and cell shrinkage after combined treatment (ultrasound and AlPcTS) was significantly higher than following other treatments, including ultrasound alone and AlPcTS alone. Furthermore, DNA ladder formation, caspase-3 activation and enhanced nitroxide generation were observed in cells treated with ultrasound and AlPcTS. Sonodynamically induced apoptosis, caspase-3 activation, and nitroxide generation were significantly suppressed by histidine. The significant reduction by histidine indicated that ultrasonically generated reactive oxygen species, such as singlet oxygen, is an important mediator of sonodynamically-induced apoptosis.

  7. Metallophthalocyanin-ocenes: scandium phthalocyanines with an η(5)-bound Cp ring.

    PubMed

    Platel, Rachel H; Teixeira Tasso, Thiago; Zhou, Wen; Furuyama, Taniyuki; Kobayashi, Nagao; Leznoff, Daniel B

    2015-04-01

    A series of new scandium complexes supported by the phthalocyanine (Pc) ligand have been prepared and structurally characterized. Reaction of ScCl3 with phthalonitrile affords a mixture of PcScCl (1) and unreacted ScCl3, which upon addition of LiCH(SiMe3)2 yields THF-soluble PcSc(μ-Cl2)Li(THF)2 (2). Metathesis with NaCp or LiCp* generates PcSc(η(5)-C5H5) and PcSc(η(5)-C5Me5), respectively, which represent the first examples of η(5)-Cp metal phthalocyanines where the Cp fragment sandwiches the metal centre.

  8. Porous Azo-Bridged Porphyrin-Phthalocyanine Network with High Iodine Capture Capability.

    PubMed

    Li, Hui; Ding, Xuesong; Han, Bao-Hang

    2016-08-01

    We report a highly efficient iodine adsorbent achieved by rational design of a porous azo-bridged porphyrin-phthalocyanine network (AzoPPN), which was synthesized by a catalyst-free coupling reaction between free-base 5,10,15,20-tetrakis(4-nitrophenyl)-porphyrin and nickel tetraaminophthlocyanine. AzoPPN has a permanent porous structure and plenty of porphyrin and phthalocyanine units in the skeleton as effective sorption sites. It displays excellent adsorption of iodine vapor up to 290 wt. % and also shows remarkable capability as adsorbent for iodine in solution. This strategy of combining physisorption with chemisorption in one adsorbent will pave the way for the development of new materials for iodine capture. PMID:27412919

  9. Development and Evaluation of Nanoemulsions Containing Phthalocyanines for Use in Photodynamic Cancer Therapy.

    PubMed

    Senna, Juliana P; Ricci-Júnior, Eduardo; Mansur, Claudia R E

    2015-06-01

    This work reports the development of oil in water (o/w) nanoemulsions containing poly(ethylene oxide)-poly(propylene oxide) block copolymer surfactant for the formulation of a delivery system for endovenous zinc and chloroaluminum phthalocyanines. A solubility study suggested clove oil and its combination with ethanol as the best candidates for the oil phase composition. The nanoemulsions were obtained using a high-pressure homogenizer and analyzed for droplet size to determine their short- and long-term stability. Formulations containing 7 and 10% oil phase and 12% surfactant presented higher stability and allowed the incorporation of a bigger amount of phthalocyanines in the formulation. Rheological analyses showed the prevailing Newtonian behavior of the nanoemulsions. Studies of toxicity and phototoxicity determined that the nanoemulsions produced were capable of inhibiting the growth of adenocarcinoma tumor cells. The nanoemulsions proved to be a good alternative for use in photodynamic therapy.

  10. Dry etching of copper phthalocyanine thin films: effects on morphology and surface stoichiometry.

    PubMed

    Van Dijken, Jaron G; Brett, Michael J

    2012-08-24

    We investigate the evolution of copper phthalocyanine thin films as they are etched with argon plasma. Significant morphological changes occur as a result of the ion bombardment; a planar surface quickly becomes an array of nanopillars which are less than 20 nm in diameter. The changes in morphology are independent of plasma power, which controls the etch rate only. Analysis by X-ray photoelectron spectroscopy shows that surface concentrations of copper and oxygen increase with etch time, while carbon and nitrogen are depleted. Despite these changes in surface stoichiometry, we observe no effect on the work function. The absorbance and X-ray diffraction spectra show no changes other than the peaks diminishing with etch time. These findings have important implications for organic photovoltaic devices which seek nanopillar thin films of metal phthalocyanine materials as an optimal structure.

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

    PubMed

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

    2011-11-01

    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.

  12. Surface Modification of Boron-Doped Diamond with Microcrystalline Copper Phthalocyanine: Oxygen Reduction Catalysis.

    PubMed

    Gan, Patrick; Foord, John S; Compton, Richard G

    2015-10-01

    Surface modification of boron-doped diamond (BDD) with copper phthalocyanine was achieved using a simple and convenient dropcast deposition, giving rise to a microcrystalline structure. Both unmodified and modified BDD electrodes of different surface terminations (namely hydrogen and oxygen) were compared via the electrochemical reduction of oxygen in aqueous solution. A significant lowering of the cathodic overpotential by about 500 mV was observed after modification of hydrogen-terminated (hydrophobic) diamond, while no voltammetric peak was seen on modified oxidised (hydrophilic) diamond, signifying greater interaction between copper phthalocyanine and the hydrogen-terminated BDD. Oxygen reduction was found to undergo a two-electron process on the modified hydrogen-terminated diamond, which was shown to be also active for the reduction of hydrogen peroxide. The lack of a further conversion of the peroxide was attributed to its rapid diffusion away from the triple phase boundary at which the reaction is expected to exclusively occur.

  13. Surface Modification of Boron-Doped Diamond with Microcrystalline Copper Phthalocyanine: Oxygen Reduction Catalysis

    PubMed Central

    Gan, Patrick; Foord, John S; Compton, Richard G

    2015-01-01

    Surface modification of boron-doped diamond (BDD) with copper phthalocyanine was achieved using a simple and convenient dropcast deposition, giving rise to a microcrystalline structure. Both unmodified and modified BDD electrodes of different surface terminations (namely hydrogen and oxygen) were compared via the electrochemical reduction of oxygen in aqueous solution. A significant lowering of the cathodic overpotential by about 500 mV was observed after modification of hydrogen-terminated (hydrophobic) diamond, while no voltammetric peak was seen on modified oxidised (hydrophilic) diamond, signifying greater interaction between copper phthalocyanine and the hydrogen-terminated BDD. Oxygen reduction was found to undergo a two-electron process on the modified hydrogen-terminated diamond, which was shown to be also active for the reduction of hydrogen peroxide. The lack of a further conversion of the peroxide was attributed to its rapid diffusion away from the triple phase boundary at which the reaction is expected to exclusively occur. PMID:26491640

  14. Graphene-enhanced intermolecular interaction at interface between copper- and cobalt-phthalocyanines

    SciTech Connect

    Dou, Wei-Dong; Huang, Shu-Ping; Lee, Chun-Sing

    2015-10-07

    Interfacial electronic structures of copper-phthalocyanine (CuPc), cobalt-phthalocyanine (CoPc), and graphene were investigated experimentally by using photoelectron spectroscopy. While the CuPc/graphene interface shows flat band structure and negligible interfacial dipole indicating quite weak molecule-substrate interaction, the CuPc/CoPc/graphene interface shows a large interfacial dipole and obvious energy level bending. Controlled experiments ruled out possible influences from the change in film structure of CuPc and pure π–π interaction between CoPc and CuPc. Analysis based on X-ray photoelectron spectroscopy and density functional theory reveals that the decrease in the work function for the CuPc/CoPc/graphene system is induced by the intermolecular interaction between CuPc and CoPc which is enhanced owning to the peculiar electronic properties at the CoPc-graphene interface.

  15. Phthalocyanine identification in paintings by reflectance spectroscopy. A laboratory and in situ study

    NASA Astrophysics Data System (ADS)

    Poldi, G.; Caglio, S.

    2013-06-01

    The importance of identifying pigments using non invasive (n.i.) analyses has gained increasing importance in the field of spectroscopy applied to art conservation and art studies. Among the large set of pigments synthesized and marketed during 20th century, surely phthalocyanine blue and green pigments occupy an important role in the field of painting (including restoration) and printing, thanks to their characteristics like brightness and fastness. This research focused on the most used phthalocyanine blue (PB15:1 and PB15:3) and green pigments (PG7), and on the possibility to identify these organic compounds using a methodology like reflectance spectroscopy in the UV, visible and near IR range (UV-vis-NIR RS), performed easily through portable instruments. Laboratory tests and three examples carried out on real paintings are discussed.

  16. In-situ spectro-microscopy on organic films: Mn-Phthalocyanine on Ag(100)

    SciTech Connect

    Al-Mahboob A.; Vescovo, E.; Sadowski, J.T.

    2013-08-18

    Metal phthalocyanines are attracting significant attention, owing to their potential for applications in chemical sensors, solar cells and organic magnets. As the electronic properties of molecular films are determined by their crystallinity and molecular packing, the optimization of film quality is important for improving the performance of organic devices. Here, we present the results of in situ low-energy electron microscopy / photoemission electron microscopy (LEEM/PEEM) studies of incorporation-limited growth [1] of manganese-phthalocyanine (MnPc) on Ag(100) surfaces. MnPc thin films were grown on both, bulk Ag(100) surface and thin Ag(100)/Fe(100) films, where substrate spin-polarized electronic states can be modified through tuning the thickness of the Ag film [2]. We also discuss the electronic structure and magnetic ordering in MnPc thin films, investigated by angle- and spin-resolved photoemission spectroscopy.

  17. Graphene-enhanced intermolecular interaction at interface between copper- and cobalt-phthalocyanines.

    PubMed

    Dou, Wei-Dong; Huang, Shu-Ping; Lee, Chun-Sing

    2015-10-01

    Interfacial electronic structures of copper-phthalocyanine (CuPc), cobalt-phthalocyanine (CoPc), and graphene were investigated experimentally by using photoelectron spectroscopy. While the CuPc/graphene interface shows flat band structure and negligible interfacial dipole indicating quite weak molecule-substrate interaction, the CuPc/CoPc/graphene interface shows a large interfacial dipole and obvious energy level bending. Controlled experiments ruled out possible influences from the change in film structure of CuPc and pure π-π interaction between CoPc and CuPc. Analysis based on X-ray photoelectron spectroscopy and density functional theory reveals that the decrease in the work function for the CuPc/CoPc/graphene system is induced by the intermolecular interaction between CuPc and CoPc which is enhanced owning to the peculiar electronic properties at the CoPc-graphene interface. PMID:26450327

  18. Surface Modification of Boron-Doped Diamond with Microcrystalline Copper Phthalocyanine: Oxygen Reduction Catalysis.

    PubMed

    Gan, Patrick; Foord, John S; Compton, Richard G

    2015-10-01

    Surface modification of boron-doped diamond (BDD) with copper phthalocyanine was achieved using a simple and convenient dropcast deposition, giving rise to a microcrystalline structure. Both unmodified and modified BDD electrodes of different surface terminations (namely hydrogen and oxygen) were compared via the electrochemical reduction of oxygen in aqueous solution. A significant lowering of the cathodic overpotential by about 500 mV was observed after modification of hydrogen-terminated (hydrophobic) diamond, while no voltammetric peak was seen on modified oxidised (hydrophilic) diamond, signifying greater interaction between copper phthalocyanine and the hydrogen-terminated BDD. Oxygen reduction was found to undergo a two-electron process on the modified hydrogen-terminated diamond, which was shown to be also active for the reduction of hydrogen peroxide. The lack of a further conversion of the peroxide was attributed to its rapid diffusion away from the triple phase boundary at which the reaction is expected to exclusively occur. PMID:26491640

  19. Depopulation of Single-Phthalocyanine Molecular Orbitals upon Pyrrolic-Hydrogen Abstraction on Graphene.

    PubMed

    Néel, Nicolas; Lattelais, Marie; Bocquet, Marie-Laure; Kröger, Jörg

    2016-02-23

    Single-molecule chemistry with a scanning tunneling microscope has preponderantly been performed on metal surfaces. The molecule-metal hybridization, however, is often detrimental to genuine molecular properties and obscures their changes upon chemical reactions. We used graphene on Ir(111) to reduce the coupling between Ir(111) and adsorbed phthalocyanine molecules. By local electron injection from the tip of a scanning tunneling microscope the two pyrrolic H atoms were removed from single phthalocyanines. The detachment of the H atom pair induced a strong modification of the molecular electronic structure, albeit with no change in the adsorption geometry. Spectra and maps of the differential conductance combined with density functional calculations unveiled the entire depopulation of the highest occupied molecular orbital upon H abstraction. Occupied π states of intact molecules are proposed to be emptied via intramolecular electron transfer to dangling σ states of H-free N atoms.

  20. Graphene-enhanced intermolecular interaction at interface between copper- and cobalt-phthalocyanines

    NASA Astrophysics Data System (ADS)

    Dou, Wei-Dong; Huang, Shu-Ping; Lee, Chun-Sing

    2015-10-01

    Interfacial electronic structures of copper-phthalocyanine (CuPc), cobalt-phthalocyanine (CoPc), and graphene were investigated experimentally by using photoelectron spectroscopy. While the CuPc/graphene interface shows flat band structure and negligible interfacial dipole indicating quite weak molecule-substrate interaction, the CuPc/CoPc/graphene interface shows a large interfacial dipole and obvious energy level bending. Controlled experiments ruled out possible influences from the change in film structure of CuPc and pure π-π interaction between CoPc and CuPc. Analysis based on X-ray photoelectron spectroscopy and density functional theory reveals that the decrease in the work function for the CuPc/CoPc/graphene system is induced by the intermolecular interaction between CuPc and CoPc which is enhanced owning to the peculiar electronic properties at the CoPc-graphene interface.

  1. Development and Evaluation of Nanoemulsions Containing Phthalocyanines for Use in Photodynamic Cancer Therapy.

    PubMed

    Senna, Juliana P; Ricci-Júnior, Eduardo; Mansur, Claudia R E

    2015-06-01

    This work reports the development of oil in water (o/w) nanoemulsions containing poly(ethylene oxide)-poly(propylene oxide) block copolymer surfactant for the formulation of a delivery system for endovenous zinc and chloroaluminum phthalocyanines. A solubility study suggested clove oil and its combination with ethanol as the best candidates for the oil phase composition. The nanoemulsions were obtained using a high-pressure homogenizer and analyzed for droplet size to determine their short- and long-term stability. Formulations containing 7 and 10% oil phase and 12% surfactant presented higher stability and allowed the incorporation of a bigger amount of phthalocyanines in the formulation. Rheological analyses showed the prevailing Newtonian behavior of the nanoemulsions. Studies of toxicity and phototoxicity determined that the nanoemulsions produced were capable of inhibiting the growth of adenocarcinoma tumor cells. The nanoemulsions proved to be a good alternative for use in photodynamic therapy. PMID:26369031

  2. Preparation and magnetic properties of phthalocyanine-based carbon materials containing transition metals

    NASA Astrophysics Data System (ADS)

    Honda, Z.; Sato, S.; Hagiwara, M.; Kida, T.; Sakai, M.; Fukuda, T.; Kamata, N.

    2016-07-01

    A simple method for the preparation of bulk quantities of magnetic carbon materials, which contain uniformly dispersed transition metals (M = Fe, Co, Ni, and Cu) as the magnetic components, is presented. By using highly chlorinated metal phthalocyanine as the building block and potassium as the coupling reagent, phthalocyanine-based carbon materials (PBCMs) containing transition metals were obtained. Our experiments demonstrate the structure of these PBCMs consists of transition metals embedded in graphitic carbon that includes a square planar MN4 magnetic core and the Fe and Co-PBCM possess spontaneous magnetization at room temperature. In addition, carbon-coated transition metal particles were obtained by the Wurtz-type reaction with excess amount of potassium coupling agent. The large transition metal surface area and magnetization of these M-PBCMs are useful for spintronic and catalytic applications.

  3. ZnO and cobalt phthalocyanine hybridized graphene: efficient photocatalysts for degradation of rhodamine B

    PubMed Central

    Neelgund, Gururaj M.; Oki, Aderemi; Luo, Zhiping

    2014-01-01

    A novel method has been developed to synthesize graphene-ZnO composite as a highly efficient catalyst by reduction of graphite oxide and in-situ deposition of ZnO nanoparticles by chemical reduction reaction. The graphene-ZnO catalyst is capable of complete degradation of rhodamine B under exposure to natural sunlight. Further, the catalytic efficiency of graphene-ZnO catalyst was enhanced by sensitizing with cobalt phthalocyanine. The formation of graphene-ZnO pcatalyst and its further sensitization with cobalt phthalocyanine was characterized using UV-vis, ATR-IR and Raman spectroscopy, powder XRD and thermogravimetric analysis. The morphology of both graphene-ZnO and graphene-ZnO-CoPC catalysts was analyzed using scanning and transmission electron microscopes. PMID:24972296

  4. Enhanced Reverse Saturable Absorption and Optical Limiting in Heavy-Atom Substituted Phthalocyanines

    NASA Technical Reports Server (NTRS)

    Perry, J. W.; Mansour, K.; Marder, S. R.; Alvarez, D., Jr.; Perry, K. J.; Choong, I.

    1994-01-01

    The reverse saturable absorption and optical limiting response of metal phthalocyaninies 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 an f/8 optical geometry, homogeneous solutions of heavy metal phthalocyanines, at 30% linear transmission, limit 8-ns, 532-nm laser pulses to less than or equal to 3 (micro)J (the energy for 50% probability of eye damage) for incident pulses up to 800 (micro)J.

  5. Clinical development of liposome-based drugs: formulation, characterization, and therapeutic efficacy

    PubMed Central

    Chang, Hsin-I; Yeh, Ming-Kung

    2012-01-01

    Research on liposome formulations has progressed from that on conventional vesicles to new generation liposomes, such as cationic liposomes, temperature sensitive liposomes, and virosomes, by modulating the formulation techniques and lipid composition. Many research papers focus on the correlation of blood circulation time and drug accumulation in target tissues with physicochemical properties of liposomal formulations, including particle size, membrane lamellarity, surface charge, permeability, encapsulation volume, shelf time, and release rate. This review is mainly to compare the therapeutic effect of current clinically approved liposome-based drugs with free drugs, and to also determine the clinical effect via liposomal variations in lipid composition. Furthermore, the major preclinical and clinical data related to the principal liposomal formulations are also summarized. PMID:22275822

  6. Enhanced combination therapy effect on paclitaxel-resistant carcinoma by chloroquine co-delivery via liposomes

    PubMed Central

    Gao, Menghua; Xu, Yuzhen; Qiu, Liyan

    2015-01-01

    A novel composite liposomal system co-encapsulating paclitaxel (PTX) with chloroquine phosphate (CQ) was designed for treating PTX-resistant carcinoma. It was confirmed that liposomal CQ can sensitize PTX by means of autophagy inhibition and competitively binding with multidrug-resistance transporters. Furthermore, according to the in vitro cytotoxicity and apoptosis assay, real-time observation of cellular uptake, and in vivo tissue distribution study, co-encapsulation of PTX and CQ in liposomes was validated as superior to the mixture of PTX liposome plus CQ liposome due to the simultaneous delivery and synergetic effect of the two drugs. Consequently, this composite liposome achieved significantly stronger anticancer efficacy in vivo than the PTX liposome plus CQ liposome mixture. This study helps to guide and enlighten ongoing and future clinical trials about the optimal administration modes for drug combination therapy. PMID:26543365

  7. Viscosity measurements of suspensions of hemoglobin-containing liposomes of varying lipid composition.

    PubMed

    Jopski, B; Pirkl, V; Schmidt, K H

    1990-01-01

    The viscosity of suspensions of hemoglobin-containing liposomes (Hb liposomes) and of liposomes without Hb was determined as a function of the shear rate. Liposomes of varying lipid composition were prepared by detergent dialysis. All liposome suspensions showed non-Newtonian viscous behavior, as did erythrocyte suspensions. The viscosity of suspensions of Hb liposomes with a bilayer consisting of egg yolk lecithin and phosphatidylserine was almost identical to erythrocyte suspension viscosity. When cholesterol was included in the lipid component of the Hb liposomes, the dependence of viscosity on the shear rate decreased (flattening of the curve), but overall suspension viscosity became higher than that of erythrocyte suspensions. Evidence is provided for the lipid concentration at which liposomes can be applied intravenously. PMID:2369656

  8. New synthetic amphiphilic polymers for steric protection of liposomes in vivo.

    PubMed

    Torchilin, V P; Trubetskoy, V S; Whiteman, K R; Caliceti, P; Ferruti, P; Veronese, F M

    1995-09-01

    Carboxy group-terminated synthetic polymers--branched poly(ethylene glycol), poly(acryloylmorpholine), and poly(vinylpyrrolidone)--were made amphiphilic by derivatization with phosphatidyl ethanolamine via the terminal carboxy group and then incorporated into lecithin-cholesterol liposomes prepared by the detergent dialysis method. Following the biodistribution of liposomes in mice, all three polymers were shown to be effective steric protectors for liposomes and were able to sharply increase liposome circulation times in a concentration-dependent manner. The accumulation of liposomes in the liver decreases. The effects observed are similar to those found for liposomes modified with linear poly(ethylene glycol). At low polymer concentration, amphiphilic branched poly(ethylene glycol) seems to be the most effective liposome protector, most probably, because at the same molar content of anchoring groups, each attachment point carries two polymeric chains and doubles the quantity of liposome-grafted polymer comparing to linear poly(ethylene glycol).

  9. New route to unsymmetrical phthalocyanine analogues by the use of structurally distorted subphthalocyanines

    SciTech Connect

    Kobayashi, Nagao; Kondo, Ryoko; Nakajima, Shinichiro; Osa, Tetsuo )

    1990-12-19

    In addition to traditional uses as dyes and in photocopying devices, phthalocyanines (Pcs) are now rapidly growing in importance in many fields such as chemical sensors, electrochromism, batteries, photodynamic cancer therapy, molecular metals, photochemical hole burning, and liquid crystals. In this communication, the authors present a completely new method for the preparation of monosubstituted type unsymmetrical Pcs and Pc analogues, which utilizes the so-called subphthalocyanines (SubPcs).

  10. Biological decolorization of reactive anthraquinone and phthalocyanine dyes under various oxidation-reduction conditions.

    PubMed

    Lee, Young H; Matthews, Rosalyn D; Pavlostathis, Spyros G

    2006-02-01

    The decolorization of two anthraquinone dyes (Reactive Blue 4 [RB4] and Reactive Blue 19 [RB19]) and two phthalocyanine dyes (Reactive Blue 7 [RB7] and Reactive Blue 21 [RB21]) was investigated at an initial dye concentration of 300 mg/L using an unacclimated, enrichment culture. The culture was fed a mixture of organic compounds and maintained initially under aerobic conditions, and then progressively developed anoxic/ anaerobic conditions. Biotransformation-related decolorization of the dyes did not take place under aerobic conditions, but use of the feed organic mixture and biomass production by the enrichment culture were not affected. Complete ammonia removal occurred in the control and all dye-amended cultures. The development and extent of nitrification were much lower in the latter cultures, in which ammonia removal via air stripping was the dominant mechanism. Prolonged incubation of the culture under anoxic/anaerobic conditions with multiple carbon source additions resulted in a high decolorization extent of anthraquinone dyes (over 84%) and only partial decolorization of phthalocyanine dyes (49 to 66%). Development of significant methanogenic activity took place in the control and, to a lesser extent, in the two phthalocyanine dye-amended cultures, but the anthraquinone dyes severely inhibited the development of methanogenic activity. The RB4 and RB19 decolorization was attributed to nonreversible, microbially mediated dye transformation(s), demonstrated by the accumulation of decolorization products with absorbance maxima in the 420- to 460-nm region. The decolorization of RB4 and RB19 followed Michaelis-Menten kinetics. At an initial dye concentration of 300 mg/L, the observed maximum decolorization rate per unit biomass was 9.1 and 37.5 mg dye/mg volatile suspended solids x day for the RB4 and RB19, respectively. Thus, partial decolorization of reactive phthalocyanine dyes and extensive biological decolorization of reactive anthraquinone dyes is

  11. Peripheral Substitution of a Near-IR-Absorbing Soluble Phthalocyanine Using "Click" Chemistry

    SciTech Connect

    Mayukh, Mayank; Lu, Chin-Wei; Hernandez, Edgardo; McGrath, Dominic V.

    2011-06-10

    A series of near-IR-absorbing soluble phthalocyanines (Pcs) with eight alkyne moieties as side chains of the chromophore have been synthesized. One of these Pcs has been used as a scaffold for functional group modification using alkyne–azide click chemistry with various azides. This led to a small library of Pcs with photo and thermal crosslinkable, dendritic, and hydrophilic moieties starting from a single Pc molecule. A patterned thin film was fabricated by photocrosslinking one of these Pc derivatives.

  12. Electronic structure of the organic semiconductor copper phthalocyanine: experiment and theory.

    PubMed

    Aristov, V Yu; Molodtsova, O V; Maslyuk, V V; Vyalikh, D V; Zhilin, V M; Ossipyan, Yu A; Bredow, T; Mertig, I; Knupfer, M

    2008-01-21

    The electronic structure of the organic semiconductor copper-phthalocyanine (CuPc) has been determined by a combination of conventional and resonant photoemission, near-edge x-ray absorption, as well as by the first-principles calculations. The experimentally obtained electronic valence band structure of CuPc is in very good agreement with the calculated density of states results, allowing the derivation of detailed site specific information.

  13. Phthalocyanine adsorption to graphene on Ir(111): Evidence for decoupling from vibrational spectroscopy

    SciTech Connect

    Endlich, M. Gozdzik, S.; Néel, N.; Kröger, J.; Rosa, A. L. da; Frauenheim, T.; Wehling, T. O.

    2014-11-14

    Phthalocyanine molecules have been adsorbed to Ir(111) and to graphene on Ir(111). From a comparison of scanning tunneling microscopy images of individual molecules adsorbed to the different surfaces alone it is difficult to discern potential differences in the molecular adsorption geometry. In contrast, vibrational spectroscopy using inelastic electron scattering unequivocally hints at strong molecule deformations on Ir(111) and at a planar adsorption geometry on graphene. The spectroscopic evidence for the different adsorption configurations is supported by density functional calculations.

  14. Femtosecond to nanosecond excited state dynamics of vapor deposited copper phthalocyanine thin films.

    PubMed

    Caplins, Benjamin W; Mullenbach, Tyler K; Holmes, Russell J; Blank, David A

    2016-04-28

    Vapor deposited thin films of copper phthalocyanine (CuPc) were investigated using transient absorption spectroscopy. Exciton-exciton annihilation dominated the kinetics at high exciton densities. When annihilation was minimized, the observed lifetime was measured to be 8.6 ± 0.6 ns, which is over an order of magnitude longer than previous reports. In comparison with metal free phthalocyanine (H2Pc), the data show evidence that the presence of copper induces an ultrafast relaxation process taking place on the ca. 500 fs timescale. By comparison to recent time-resolved photoemission studies, this is assigned as ultrafast intersystem crossing. As the intersystem crossing occurs ca. 10(4) times faster than lifetime decay, it is likely that triplets are the dominant excitons in vapor deposited CuPc films. The exciton lifetime of CuPc thin films is ca. 35 times longer than H2Pc thin films, while the diffusion lengths reported in the literature are typically quite similar for the two materials. These findings suggest that despite appearing to be similar materials at first glance, CuPc and H2Pc may transport energy in dramatically different ways. This has important implications on the design and mechanistic understanding of devices where phthalocyanines are used as an excitonic material.

  15. Structure and bonding in alpha-copper phthalocyanine by electron diffraction.

    PubMed

    Wu, J S; Spence, J C H

    2003-09-01

    Energy-filtered quantitative electron diffraction at liquid nitrogen temperature has been used to examine the atomic structure and bonding of metastable alpha-Cu phthalocyanine crystals. Three theoretical methods (kinematic, kinematic with excitation errors and Bloch wave) were employed for the intensity calculations. The Bloch-wave method was found to account for dynamical effects by greatly reducing the residual factor between experimental and simulated results. A new method for calculating electron scattering factors for partially charged ions is proposed and the sensitivity of electron diffraction to charge transfer is discussed. The atomic charge states were analyzed for alpha-Cu phthalocyanine using a charge cloud model in which the Gaussian bond charge is positioned along the bonds. Spot patterns were collected in the Kohler mode at two beam energies to reduce error. Using the best-fitting model, a deformation charge-density map is produced and compared to the neutral-atom model. From this, the main features of atomic charge transfer in the alpha-Cu phthalocyanine structure can be seen in the (010) plane.

  16. An Electrochemical Quartz Crystal Microbalance Multisensor System Based on Phthalocyanine Nanostructured Films: Discrimination of Musts

    PubMed Central

    Garcia-Hernandez, Celia; Medina-Plaza, Cristina; Garcia-Cabezon, Cristina; Martin-Pedrosa, Fernando; del Valle, Isabel; de Saja, Jose Antonio; Rodríguez-Méndez, Maria Luz

    2015-01-01

    An array of electrochemical quartz crystal electrodes (EQCM) modified with nanostructured films based on phthalocyanines was developed and used to discriminate musts prepared from different varieties of grapes. Nanostructured films of iron, nickel and copper phthalocyanines were deposited on Pt/quartz crystals through the Layer by Layer technique by alternating layers of the corresponding phthalocyanine and poly-allylamine hydrochloride. Simultaneous electrochemical and mass measurements were used to study the mass changes accompanying the oxidation of electroactive species present in must samples obtained from six Spanish varieties of grapes (Juan García, Prieto Picudo, Mencía Regadío, Cabernet Sauvignon, Garnacha and Tempranillo). The mass and voltammetric outputs were processed using three-way models. Parallel Factor Analysis (PARAFAC) was successfully used to discriminate the must samples according to their variety. Multi-way partial least squares (N-PLS) evidenced the correlations existing between the voltammetric data and the polyphenolic content measured by chemical methods. Similarly, N-PLS showed a correlation between mass outputs and parameters related to the sugar content. These results demonstrated that electronic tongues based on arrays of EQCM sensors can offer advantages over arrays of mass or voltammetric sensors used separately. PMID:26610494

  17. Electronic absorption band broadening and surface roughening of phthalocyanine double layers by saturated solvent vapor treatment

    SciTech Connect

    Kim, Jinhyun; Yim, Sanggyu

    2012-10-15

    Variations in the electronic absorption (EA) and surface morphology of three types of phthalocyanine (Pc) thin film systems, i.e. copper phthalocyanine (CuPc) single layer, zinc phthalocyanine (ZnPc) single layer, and ZnPc on CuPc (CuPc/ZnPc) double layer film, treated with saturated acetone vapor were investigated. For the treated CuPc single layer film, the surface roughness slightly increased and bundles of nanorods were formed, while the EA varied little. In contrast, for the ZnPc single layer film, the relatively high solubility of ZnPc led to a considerable shift in the absorption bands as well as a large increase in the surface roughness and formation of long and wide nano-beams, indicating a part of the ZnPc molecules dissolved in acetone, which altered their molecular stacking. For the CuPc/ZnPc film, the saturated acetone vapor treatment resulted in morphological changes in mainly the upper ZnPc layer due to the significantly low solubility of the underlying CuPc layer. The treatment also broadened the EA band, which involved a combination of unchanged CuPc and changed ZnPc absorption.

  18. NIR photocleavage of the Si-C bond in axial Si-phthalocyanines.

    PubMed

    Doane, Tennyson; Cheng, Yu; Sodhi, Nipun; Burda, Clemens

    2014-11-13

    The use of light-triggered photolysis provides a powerful tool for unique syntheses and for applications that require remote operation such as drug delivery or molecular switches. Here, we describe the photochemistry of a recently developed alkylsilicon phthalocyanine Pc 227, which undergoes an exchange of the alkyl ligand for a ligand derived from the solvent when the axial Si-C bond is photolyzed in a solvent with low-energy visible light. In this work with methanol as the solvent, we investigate the formation of the methoxy analogue of the therapeutic drug Pc 4, (termed Pc 233) upon irradiation. Using steady-state spectroscopy and characterization of the photoproducts, the competing pathways between direct ligand exchange on the central silicon atom and delocalization of the radical produced by homolysis on the phthalocyanine ring is observed. The delocalized radical intermediate is quite long-lived. At long times this intermediate decomposes without significant formation of Pc 233. The results of this investigation provide insights into recent work utilizing Pc 227 for drug delivery applications and for future work on the use of phthalocyanines as long-wavelength phototriggers.

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

    PubMed

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

    2013-10-21

    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.

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

    PubMed

    Jančula, Daniel; Maršálek, Blahoslav; Babica, Pavel

    2013-10-01

    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 60 min 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 (1.25-20 mg L(-1) or 0.625-10 mg L(-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.