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Biomedical subjects

Antonino Mazzaglia

Publications and source records attributed to Antonino Mazzaglia.

7 recordsLinked to original sources
PubMed2006

Nanoparticles of cationic amphiphilic cyclodextrins entangling anionic porphyrins as carrier-sensitizer system in photodynamic cancer therapy.

The photodynamic activity of a carrier-sensitizer system consisting of heterotopic colloidal nanoparticles (diameter 100-1000 nm) of a cationic amphiphilic cyclodextrin, heptakis(2-omega-amino-O-oligo(ethylene oxide)-6-hexylthio)-beta-CD (SC6CDNH2) encapsulating the anionic 5,10,15,20-tetrakis(4-sulfonatophenyl)-21H,23H-porphyrin (TPPS) is investigated by an interdisciplinary approach involving the combination of time-resolved absorption and emission techniques with in vitro studies on cultured tumor cells. In a range of TPPS:SC6CDNH2 molar ratios between 1:10 and 1:50 these nanoparticles preserve the photodynamic properties of the entrapped photoactive agent. In fact, the triplet state of TPPS is efficiently populated, very long-lived and, as a consequence, able to produce singlet oxygen (the essential species for the photodynamic action) with quantum yield comparable to the free TPPS. Photodynamic efficacy of the carrier/sensitizer system is proven by in vitro studies on tumor Hela cells treated with TPPS:SC6CDNH2 at different molar ratio, showing significant cells death upon illumination with visible light.

Cyclodextrins↗
PubMed2005

Amphiphilic cyclodextrin carriers embedding porphyrins: charge and size modulation of colloidal stability in heterotopic aggregates.

The interaction between the anionic 5,10,15,20-tetrakis(4-sulfonatophenyl)-21H,23H-porphyrin (TPPS) and cationic vesicles formed by heptakis(2-omega-amino-O-oligo(ethylene oxide)-6-hexylthio)-beta-cyclodextrin (SC6CDNH2) has been investigated in detail through a combination of elastic light scattering (ELS), quasi-elastic light scattering (QELS), zeta potential measurements, and time-resolved fluorescence anisotropy. ELS experiments provided the first structural characterization of these cationic vesicles both in the absence and in the presence of TPPS porphyrin, modeling the system as a spherical particle described by a single thin shell form factor. The structure of mixed hetero-aggregates is modulated by charge and size of the two components as function of different porphyrin/cyclodextrin (CD) molar ratios. At the limiting molar ratio studied, the absolute value of zeta potential (/zeta/ = 12.5 mV) seems to be a reference value for the formation of stable colloidal CD vesicular aggregates at thermodynamic equilibrium. New insights on the structure of these heterotopic colloids have been obtained by analysis of rotational correlation times at different molar ratios exploiting time-resolved fluorescence anisotropy experiments. At high porphyrin loads, the anisotropy decays behave as monoexponentials and the rotational correlation times (1-2 ns) together with the r(0) values close to zero suggest the presence of small amounts of TPPS embedded in a hydrophobic environment either in monomeric or in aggregated form. At the lower porphyrin/CD molar ratios, the anisotropy decays exhibit a double-exponential behavior showing a predominant component with a slow rotational correlation time (20-25 ns) and limiting anisotropy values of approximately 0.15. This component has been assigned to molecules that are more stabilized onto the CD vesicles, that is, porphyrins embedded into the oligo-ethylene "wall" of the CD vesicles. Scanning near-field optical microscopy of the samples evaporated on glass surfaces gave further insights on the morphology and optical properties of these systems, confirming the embedding of TPPS on the vesicles and evidencing the role of the solvent.

Anions↗
PubMed2004

Structural properties of nonionic cyclodextrin colloids in water.

The amphiphilic character in water of a novel class of chemically modified cyclodextrins has been investigated by means of small-angle X-ray scattering and light scattering. The introduction ofhydrophilic oligo(ethylene glycol) onto the secondary side of heptakis[6-alkylthio-6-deoxy-2-oligo(ethylene glycol)]-beta-cyclodextrins produces an enhanced water solubility of these molecules. Shape and dimensions of the generated micellar aggregates, analyzed in terms of a suitable core-shell model, remain stable in the wide concentration range explored. The highly associative behavior of these macromolecules is evidenced by the very low value of the critical micelle concentration (cmc), which is about 2 orders of magnitude smaller than the cmc usually obtained for traditional surfactant. Despite the complex geometry of this novel macromolecule, shape and dimensions of generated micellar aggregates can be properly described according to the thermodynamic approaches generally used for amphiphilic molecules and block copolymers. Results show how the modulation of hydrophobic and hydrophilic components sensitively influence the structural features of the generated aggregates thus offering the possibility to control molecular organization in a manner similar to that for traditional colloids. For all the classes of the investigated systems, the small micelles have been found in equilibrium with polydisperse large aggregates of entangled micelles. These novel nonionic colloidal systems combine inclusion and transport properties of host macrocycles, such as cyclodextrin, together with the increased stability of colloidal aggregates, and may be of interest for their potential application as innovative drug delivery systems.

Circular Dichroism↗
PubMed2003

Novel heterotopic colloids of anionic porphyrins entangled in cationic amphiphilic cyclodextrins: spectroscopic investigation and intracellular delivery.

The entanglement process between water-soluble 5,10,15,20-tetrakis(4-sulfonatophenyl)-21H,23H-porphine and the amphiphilic cyclodextrin (CD) heptakis(2-omega-amino-O-oligo(ethylene oxide)-6-hexylthio)-beta-CD and the occurrence of various species at different porphyrin:CD ratios were studied by a combination of UV/Vis absorption, fluorescence anisotropy, time-resolved fluorescence, resonance light scattering, and circular dichroism. The effect of the entanglement process on the mean vesicle diameter was investigated over a wide concentration range by quasielastic light-scattering techniques. The experimental results indicate that the presence of porphyrins in this colloidal system promotes some structural rearrangements, essentially driven by charge interaction, which are responsible for a sensitive change of vesicle dimensions. In the range of porphyrin:CD molar ratios between 1:10 and 1:50, the porphyrin is solubilized in monomeric form (tau(1)=11.5 ns) and photosensitizes the production of singlet oxygen ((1)O(2)). At the same molar ratio the ability of this amphiphilic cyclodextrin to transport porphyrins into tumor cells indicates specificity at the nuclear-compartment level. These findings may be of potential interest for the of development agents for photodynamic therapy of tumors.

Animals↗
PubMed2002

Cationic beta-cyclodextrin bilayer vesicles.

Cationic amphiphilic beta-cyclodextrins, substituted with hydrophobic n-alkylthio chains at the primary hydroxyl side and hydrophilic omega-amino-oligo(ethylene glycol) units at the secondary side, form bilayer vesicles with a diameter of 30-35 nm (when alkyl = hexadecyl) or nanoparticles with a diameter of ca. 120 nm (when alkyl = hexyl) in water.

Journal Article↗
PubMed2002

Synthetic procedures to monomethyl-platinum(II) complexes containing nitrogen ligands of biological relevance.

The complex trans-bis(dimethylsulfoxide)chloromethylplatinum(II) (1) is fairly soluble in water, where it undergoes multiple equilibria involving the formation of geometrically distinct [Pt(H(2)O)(DMSO)Cl(CH(3))] aqua-species. On reacting an aqueous solution of 1 with monodentate nitrogen donor ligands L, such as pyridines or amines, two well distinct patterns of behavior can be recognized: (i) a single stage fast substitution of one DMSO by the entering ligand, yielding a complex of the type trans(C,N)-[Pt(DMSO)(L)Cl(CH(3))] which contains four different groups coordinated to the metal and which undergoes a slow conversion into its cis-isomer, (ii) a double substitution affording cationic complex ions of the type cis-[Pt(L)(2)(DMSO)(CH(3))](+). When this latter reaction is carried out using sterically hindered ligands, slow rotation of the bulk ligand around the Pt[bond]N bond allows for the identification of head-to-head and head-to-tail rotamers in solution, through (1)H NMR spectrometry. The addition of chloride anion to 1 leads to the anionic species cis-[Pt(DMSO)Cl(2)(CH(3))](-), where a molecule of DMSO still remains coordinated to the metal center, despite its quite fast rate of ligand exchange (k(exch) with free DMSO=12+/-1 s(-1)). The reaction of complex 1 with bidentate ligands, such as ethylenediamine (en) or simple amino acids, leads to the cationic species [Pt(en)(DMSO)(CH(3))](+) or to the neutral [Pt(DMSO)(N[bond]O)(CH(3))], (where N[bond]-O[double bond]GlyO(-), AlaO(-)).

Amino Acids↗