Physicochemical characterizations of functional hybrid liposomal nanocarriers formed using photo-sensitive lipids (original) (raw)
Related papers
Dye-sensitized destabilization of liposomes bearing photooxidizable lipid head groups
Photochemistry and photobiology, 1993
Liposomes were prepared from mixtures of dipalmitoyl-L-alpha-phosphatidylcholine and up to 40% mol:mol of N-stearoyl-L-histidine (NSH) in the presence of the hydrophobic sensitizer DHE. In the dark such liposomes are stable and retain entrapped salts. On photolysis with visible light, liposomes leak trapped ions at NSH concentrations greater than 10% mol:mol. Up to 15% mol:mol NSH concentration leakage is seen only during the illumination period, whereas at higher concentration the liposomes continue to leak contents after illumination and fuse to form larger structures. Photolysis of the liposomes is accompanied by oxygen uptake in proportion to the NSH concentration within the bilayer. Photocontrol of liposome permeability through oxidation of membrane additives such as NSH offers a potential means for controlled drug delivery and might be useful as an adjunct to photodynamic therapy.
Theranostic verteporfin- loaded lipid-polymer liposome for photodynamic applications
Journal of Photochemistry and Photobiology B: Biology, 2020
In this study we report a novel theranostic lipid-polymer liposome, obtained from DPPC and the triblock copolymer F127 covalently modified with 5(6)-carboxyfluorescein (CF) for photodynamic applications. Due to the presence of F127, small unilamellar vesicle (SUV) liposomes were synthesized by a simple and fast thin-film hydration method without the need for an extrusion process. The vesicles have around 100 nm, low polydispersity and superb solution stability. The clinically used photosensitizer verteporfin (VP) was entrapped into the vesicles, mostly in monomeric form, with 90% loading efficiency. Stern-Volmer and fluorescence lifetime assays showed heterogeneous distribution of the VP and CF into the vesicles, ensuring the integrity of their individual photophysical properties. The theranostic properties were entirely photoactivatable and can be trigged by a unique wavelength (470 nm). The feasibility of the system was tested against the Glioblastoma multiforme cell line T98G. Cellular uptake by time-resolved fluorescence microscopy showed monomerized VP (monoexponential decay, 6.0 ns) at nucleus level, while CF was detected at the membrane by fluorescence microscopy. The strategy's success was supported by the reduction of 98% in the viability of T98G cells by the photoactivated lipid-polymer liposome with [VP] = 1.0 μmol L −1. Therefore, the novel theranostic liposome is a potential system for use in cancer and ocular disease therapies.
Biochimica et Biophysica Acta (BBA) - Biomembranes, 2005
Three cholesterol derivatives containing an azobenzene moiety with different polarities were designed and synthesized (AB lipids 1 to 3). The effects of structure, temperature and incorporation ratio on liposomes were studied, with the results showing that the polarity in 4-substituent and in some cases, 4V-substituent may be important for their incorporation feasibility and photoisomerizability in liposomes. Liposomes incorporated with AB lipid 3 could release multi-pulsatilely upon UV and visible light irradiation both in gel state and liquid crystal state of liposomes. An increase in the incorporation ratio of AB lipid 3 enhanced the amount of drug released greatly. Unlike other azobenzene photo-triggers reported, AB lipid 3 did not increase the spontaneous release of liposomes. Furthermore, cholesterol suppressed the spontaneous release of liposomes.
Photodynamic ultradeformable liposomes: Design and characterization
International journal of pharmaceutics, 2007
Hydrophobic ([tetrakis(2,4-dimetil-3-pentyloxi)-phthalocyaninate]zinc(II)) (ZnPc) and hydrophilic ([tetrakis(N,N,N-trimethylammoniumetoxi)phthalocyaninate]zinc(II) tetraiodide) (ZnPcMet) phthalocyanines were synthesized and loaded in ultradeformable liposomes (UDL) of soybean phosphatidylcholine and sodium cholate (6:1, w/w, ratio), resulting 100 nm mean size vesicles of negative Zeta potential, with encapsulation efficiencies of 85 and 53%, enthalpy of phase transition of 5.33 and 158 J/mmol for ZnPc and ZnPcMet, respectively, indicating their deep and moderate partition into UD matrices. Matrix elasticity of UDL-phthalocyanines resulted 28-fold greater than that of non-UDL, leaking only 25% of its inner aqueous content after passage through a nanoporous barrier versus 100% leakage for non-UDL. UDL-ZnPc made ZnPc soluble in aqueous buffer while kept the monomeric state, rendering singlet oxygen quantum yield (Φ Δ ) similar to that obtained in ethanol (0.61), whereas UDL-ZnPcMet had a four-fold higher Φ Δ than that of free ZnPcMet (0.21). Free phthalocyanines were non-toxic at 1 and 10 M, both in dark or upon irradiation at 15 J/cm 2 on Vero and J-774 cells (MTT assay). Only liposomal ZnPc at 10 M was toxic for J-774 cells under both conditions. Aditionally, endo-lysosomal confinement of the HPTS dye was kept after irradiation at 15 J/cm 2 in the presence of UDL-phtalocyanines. This could lead to improve effects of singlet oxygen against intra-vesicular pathogen targets inside the endo-lysosomal system.
Photochemical & Photobiological Sciences, 2011
We studied the effects of density and thickness of PEG coating on in vitro cellular uptake, and dark-and photo-toxicity of liposomal formulations (Fospeg) of the photodynamic agent meta-tetrahydroxyphenyl chlorin (m-THPC). The cellular uptake of various Fospeg formulations was determined by flow cytometry in CCD-34Lu human normal fibroblasts and A549 lung cancer cells. Dark and light-induced cytotoxicity was measured by MTS assay after exposure to increasing concentrations of Fospeg only and followed by irradiation with red light. Intracellular localization of m-THPC delivered by Fospeg was determined by fluorescence microscopy. The studies were carried out in comparison with m-THPC delivered by the standard solvent. In the dark all Fospeg formulations were less cytotoxic than m-THPC in standard solvent (ethanol/poly(ethylene glycol 400/water; 20 : 30 : 50 by vol.) and cytotoxicity decreased by increasing PEGylation. m-THPC delivered as Fospeg was internalised by endocytosis and localised mainly in the Golgi apparatus and endoplasmic reticulum. The efficiency of cellular uptake of Fospeg was reduced by 30-40% with respect to m-THPC in standard solution causing a slight reduction of the phototoxicity but without serious impairment of the efficacy of the treatment. Our study suggests that PEGylated liposomes are promising nanocarriers for the delivery of photosensitisers for photodynamic therapy because they reduce dark cytotoxicity while preserving therapeutic efficacy.
Self-assembled liposomal nanoparticles in photodynamic therapy
European Journal of Nanomedicine, 2013
Photodynamic therapy (PDT) employs the combination of non-toxic photosensitizers (PS) together with harmless visible light of the appropriate wavelength to produce reactive oxygen species that kill unwanted cells. Because many PS are hydrophobic molecules prone to aggregation, numerous drug delivery vehicles have been tested to solubilize these molecules, render them biocompatible and enhance the ease of administration after intravenous injection. The recent rise in nanotechnology has markedly expanded the range of these nanoparticulate delivery vehicles beyond the well-established liposomes and micelles. Self-assembled nanoparticles are formed by judicious choice of monomer building blocks that spontaneously form a well-oriented 3-dimensional structure that incorporates the PS when subjected to the appropriate conditions. This self-assembly process is governed by a subtle interplay of forces on the molecular level. This review will cover the state of the art in the preparation and use of self-assembled liposomal nanoparticles within the context of PDT.
Photoinitiated destabilization of sterically stabilized liposomes
Biochimica et Biophysica Acta (BBA) - Biomembranes, 2001
THE UNIVERSITY OF ARIZONA GRADUATE COLLEGE As members of the Final Examination Committee, we certify that we have read the dissertation prepared by Paul Anthony Spratt entitled Photoinitiated Destabilization of Sterically Stabilized Liposomes for Enhanced Drug Delivery and recommend chat it be accepted as fulfilling Che dissertation requirement for the Degree of Doctor Of Philosophy Eugene A.< sh Jr. Date S. S. Saavedra Date ro I ^ Indraneel Ghosh K. McGovern Rupley Date DisseM^cion Direccor Dace times. Losing Dr. O'Brien was a terrible tragedy and his presence is surely missed In the completion of this work. I will always remember Dr. O'Brien fondly as a friend and mentor who expected the best from his students and gave his best to the community.
Biomolecular Science of Liposome-Nanoparticle Constructs
Molecular Crystals and Liquid Crystals, 2009
Phospholipid-nanoparticle constructs, formed by allowing nanoparticles to adsorb to the outer leaflet of liposomes, are found to be stabilized against fusion with one another. Here, through single-particle tracking by epifluorescence microscopy, we explore their use as novel colloidal particles -flexible and hollow colloidal particles that contrast strikingly with colloids of the conventional type. At the singleliposome level, the distribution of diffusion coefficients is quantified. Biomolecular function is addressed through experiments in which we explore the access of receptor to liposome-immobilized ligand, finding that receptor binding persists over a range of nanoparticle surface coverage where liposome fusion and large-scale aggregation is prevented. This opens the door to designing newer and more flexible types of tailor-made materials with desirable functionality.