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Anand R.,CNR Institute of Neuroscience | Malanga M.,Cyclodextrin RandD Ltd. | Manet I.,CNR Institute of Neuroscience | Manoli F.,CNR Institute of Neuroscience | And 7 more authors.
Photochemical and Photobiological Sciences | Year: 2013

Two citric acid crosslinked γ-cyclodextrin oligomers (pγ-CyD) with a MW of 21-33 kDa and 10-15 γ-CyD units per molecule were prepared by following green chemistry methods and were fully characterized. The non-covalent association of doxorubicin (DOX) with these macromolecules was investigated in neutral aqueous medium by means of circular dichroism (CD), UV-vis absorption and fluorescence. Global analysis of multiwavelength spectroscopic CD and fluorescence titration data, taking into account the DOX monomer-dimer equilibrium, evidenced the formation of 1:1 and 1:2 pγ-CyD unit-DOX complexes. The binding constants are 1-2 orders of magnitude higher than those obtained for γ-CyD and depend on the characteristics of the oligomer batch used. The concentration profiles of the species in solution evidence the progressive monomerization of DOX with increasing oligomer concentration. Confocal fluorescence imaging and spectral imaging showed a similar drug distribution within the MCF-7 cell line incubated with either DOX complexed to pγ-CyD or free DOX. In both cases DOX is taken up into the cell nucleus without any degradation. © 2013 The Royal Society of Chemistry and Owner Societies.

Malanga M.,Cyclodextrin RandD Ltd. | Darcsi A.,Semmelweis University | Balint M.,Cyclodextrin RandD Ltd. | Benkovics G.,Cyclodextrin RandD Ltd. | And 3 more authors.
Beilstein Journal of Organic Chemistry | Year: 2016

Xanthene dyes can be appended to cyclodextrins via an ester or amide bridge in order to switch the fluorescence on or off. This is made possible through the formation of nonfluorescent lactones or lactams as the fluorophore can reversibly cyclize. In this context we report a green approach for the synthesis of switchable xanthene-dye-appended cyclodextrins based on the coupling agent 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMT-MM). By using 6-monoamino-β-cyclodextrin and commercially available inexpensive dyes, we prepared rhodamine- and fluorescein-appended cyclodextrins. The compounds were characterized by NMR and IR spectroscopy and MS spectrometry, their UV-vis spectra were recorded at various pH, and their purity was determined by capillary electrophoresis. Two potential models for the supramolecular assembly of the xanthene-dyeappended cyclodextrins were developed based on the set of data collected by the extensive NMR characterization. © 2016 Malanga et al; licensee Beilstein-Institut.

Benkovics G.,Charles University | Benkovics G.,Cyclodextrin RandD Ltd. | Hodek O.,Charles University | Havlikova M.,Charles University | And 7 more authors.
Beilstein Journal of Organic Chemistry | Year: 2016

This work focuses on the preparation and application of supramolecular structures based on mono-cinnamyl-α-cyclodextrins (Cin-α-CD). Pure regioisomers of Cin-α-CD having the cinnamyl moiety at the 2-O-or at the 3-O-position, respectively, were prepared, characterized and applied in capillary electrophoresis as additives to the background electrolyte. These new monomer units with a potential to self-organize into supramolecular structures were synthesized via a straightforward one-step synthetic procedure and purified using preparative reversed-phase chromatography allowing a large scale separation of the regioisomers. The ability of the monomers to self-assemble was proved by various methods including NMR spectroscopy and dynamic light scattering (DLS). The light scattering experiments showed that the monomer units have distinguishable ability to form supramolecular structures in different solvents and the size distribution of the aggregates in water can be easily modulated using different external stimuli, such as temperature or competitive guest molecules. The obtained results indicated that the two regioisomers of Cin-α-CD formed different supramolecular assemblies highlighting the fact that the position of the cinnamyl group plays an important role in the intermolecular complex formation. © 2016 Benkovics et al; licensee Beilstein-Institut.

Anand R.,CNR Institute for Organic Syntheses and Photoreactivity | Manoli F.,CNR Institute for Organic Syntheses and Photoreactivity | Manet I.,CNR Institute for Organic Syntheses and Photoreactivity | Donzello M.P.,University of Rome La Sapienza | And 5 more authors.
RSC Advances | Year: 2014

A nitro-benzofurazan-triazolyl carboxymethylated β-cyclodextrin (NBFT-CMβCyD) and an oligomer of carboxymethyl β-cyclodextrin (sodium salt), crosslinked with epichlorohydrin and labeled with rhodaminyl groups (pβCyD-Rh), exhibit very high affinity in aqueous solution for octacationic photosensitizer [(CH3)8LZn]8+ neutralized by I- ions (L = tetrakis-2,3-[5,6-di(2-(pyridiniumyl)pyrazino] porphyrazinato dianion). The photosensitizer (PS) forms complexes with 1 : 2 and 2 : 2 CyD:PS stoichiometry, which were characterized as binding constants and UV-Vis absorption and fluorescence properties. The self-association tendency of [(CH3)8LZn]8+, leading to a monomer-dimer equilibrium shift towards the dimer even at very low concentrations (≈10 -6 M), is not contrasted by either NBFT-CMβCyD or the pβCyD-Rh oligomer, both of which completely convert the [(CH 3)8LZn]8+ monomer fraction to the dimer form in the bound state. Quenching of fluorescence observed in [(CH3) 8LZn]8+ upon binding with either hosts is consistent with the conversion of the monomer to the negligibly fluorescent dimer. The complexes formed with the CMβCyD units of the pβCyD-Rh oligomer have average association constants, which are larger by 6-7 orders of magnitude than those with the CMβCyD monomer in the NBFT-labeled derivative. © 2014 the Partner Organisations.

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