Paola Fini

Functionalized Copper(II)−Phthalocyanine in Solution and As Thin Film: Photochemical and Morphological Characterization toward Applications

This article reports on an extensive investigation on a functionalized phthalocyanine, namely, copper(II) tetrakis-(isopropoxy-carbonyl)-phthalocyanine (TIPCuPc). The self-association of the molecules is extensively described in solution in different solvents (DMSO, DMF, CHCl(3), pyridine) by means of UV-vis steady state spectroscopy at the air/water interface by Brewster angle microscopy (BAM) and in thin films by using atomic force microscopy (AFM). We investigated the morphology of TIPCuPc as thin film by evaluating different factors: temperature, solvent, concentration, transferring procedure (spin-coating and Langmuir-Schafer technique), and nature of the substrate (mica and quartz). The behavior of the molecules under UV light irradiation and their thermal stability were studied as well. Such a detailed study can allow a suitable processing of this phthalocyanine derivative for future applications. Here the photoelectrochemical activity of the phthalocyanine was investigated when suitably combined as sensitizer with rodlike TiO(2) nanocrystals (NCs) in hybrid junctions integrated in a photoelectrochemical cell.

Aggregation processes and photophysical properties of chlorophyll a in aqueous solutions modulated by the presence of cyclodextrins

In the present paper we report the preliminary results on the behaviour of chlorophyll a (Chl a), the main photosynthetic amphiphilic pigment of green plants, in water and aqueous solutions of cyclodextrins (α-cyclodextrin, hydroxypropyl-β-cyclodextrin, heptakis(2,6-di-O-methyl)-β-cyclodextrin and hydroxypropyl-γ-cyclodextrin). In particular our study was aimed to understand the influence of CDs on solubility and aggregation of Chl a in water and to get information on the interactions between different cyclodextrins and the pigment. The role played by different CDs in affecting the photoactivity of the chlorophyll, with particular attention to the quantum yield of the singlet oxygen production, has been also discussed. The study was carried out by using different spectroscopic (UV–Vis, fluorescence, circular dichroism, time resolved absorption and luminescence) and calorimetric (ITC) techniques.

Tetrakis(4-pyridyl)porphyrin Supramolecular Complexes with Cyclodextrins in Aqueous Solution

Abstract The formation of inclusion complexes of hydroxypropyl-β-cyclodextrin, heptakis(2,6-di-O-methyl)-β-cyclodextrin and heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin with 5,10,15,20-tetrakis(4-pyridyl)porphyrin (TpyP) has been studied in aqueous buffer solution (phosphate buffer pH = 7 and I = 0.01 M) to give a structural and spectroscopic characterization of a new class of potential sensitizers for photodynamic therapy. The interaction was investigated by a combination of UV/Vis absorption, fluorescence anisotropy, time-resolved fluorescence and circular dichroism. The experimental results point to the presence of the pigment in water in a monomeric complexed form. The fluorescence anisotropy measurements suggest that TpyP forms 1:1 complexes with heptakis(2,3,6-tri-O-methyl)-β-cyclodextrin and hydroxypropyl-β-cyclodextrin, while 1:2 complexes are obtained with heptakis(2,6-di-O-methyl)-β-cyclodextrin.

α-Cyclodextrin encapsulation of supercritical CO2 extracted oleoresins from different plant matrices: A stability study

Here we describe the encapsulation in α-cyclodextrins (α-CDs) of wheat bran, pumpkin and tomato oleoresins, extracted by supercritical carbon dioxide, to obtain freeze-dried powders useful as ready-to-mix ingredients for novel functional food formulation. The stability of tocochromanols, carotenoids and fatty acids in the oleoresin/α-CD complexes, compared to the corresponding free oleoresins, was also monitored over time in different combinations of storage conditions. Regardless of light, storage at 25°C of free oleoresins determined a rapid decrease in carotenoids, tocochromanols and PUFAs. α-CD encapsulation improved the stability of most bioactive compounds. Storage at 4°C synergized with encapsulation in preventing degradation of bioactives. Unlike all other antioxidants, lycopene in tomato oleoresin/α-CD complex resulted to be more susceptible to oxidation than in free oleoresin, likely due to its selective sequestration from the interaction with other lipophilic molecules of the oleoresin.

Identification of Ros Produced by Photodynamic Activity of Chlorophyll/Cyclodextrin Inclusion Complexes

Photodynamic therapy (PDT) is a way of treating malignant tumors and hyperproliferative diseases. It is based on the use of photosensitizer, herein the chlorophyll a (chl a), and a light of an appropriate wavelength. The interaction of the photosensitizer (PS) with the light produces reactive oxygen species (ROS), powerful oxidizing agents, which cause critical damage to the tissue. To solubilize chl a in aqueous solution and to obtain it as monomer, we have used cyclodextrins, carriers which are able to interact with the pigment and form the inclusion complex. The aim of this study is to examine which types of ROS are formed by Chl a/cyclodextrin complexes in phosphate buffered solution and cell culture medium, using specific molecules, called primary acceptors, which react selectively with the reactive species. In fact the changes of the absorption and the emission spectra of these molecules after the illumination of the PS provide information on the specific ROS formation. The 1O2 formation has been tested using chemical methods based on the use of Uric Acid (UA), 9,10‐diphenilanthracene (DPA) and Singlet oxygen sensor green (SOSG) and by direct detection of Singlet Oxygen (1O2) luminescence decay at 1270 nm. Moreover, 2,7‐dichlorofluorescin and ferricytochrome c (Cyt Fe3+) have been used to detect the formation of hydrogen peroxide and superoxide radical anion, which reduces Fe3+ of the ferricytochrome to Fe2+, respectively.

Rose Bengal-photosensitized oxidation of 4-thiothymidine in aqueous medium: evidence for the reaction of the nucleoside with singlet state oxygen

The photoreactivity of 4-thiothymidine (S(4)TdR) under visible light in the presence of Rose Bengal (RB), acting as a photosensitizer, was investigated in aqueous solutions at pH 7 and 12, using UV-vis, FTIR-ATR and (1)H-NMR spectroscopic techniques, time resolved absorption spectroscopy and electrospray ionization mass spectrometry (ESI-MS). Evidence for the generation of thymidine (TdR) as the main product, after one hour of irradiation, was obtained from UV-Vis data, that suggested 4-thiothymidine photodegradation to be faster at basic pH, and confirmed by FTIR-ATR and (1)H-NMR data. Clues for the presence of a further product, likely corresponding to a dimeric form of S(4)TdR, were obtained from the latter techniques. Besides indicating the presence of thymidine, the ESI-MS and MS/MS spectra of the reaction mixtures enabled the identification of the additional product as a S-S bridged covalent dimer of 4-thiothymidine. The concentration of the dimeric species could be estimated with the aid of (1)H-NMR data and was found to be lower than that of thymidine in pH 7 reaction mixtures and almost negligible in the pH 12 ones. From a mechanistic point of view, time-resolved absorption spectroscopy measurements provided direct evidence that the formation of the two products cannot be ascribed to a photoinduced electron transfer involving S(4)TdR and the excited triplet state of RB. Rather, their generation can be interpreted as the result of a bimolecular reaction occurring between singlet state oxygen ((1)O2), photogenerated by RB, and S(4)TdR, as demonstrated by the direct detection of (1)O2 through IR luminescence spectroscopy. More specifically, a sequential reaction pathway, consisting in the generation of an electrophilic hydroxylated form of S(4)TdR and its subsequent, rapid reaction with S(4)TdR, was hypothesized to explain the presence of the S-S bridged covalent dimer of 4-thiothymidine in the reaction mixtures. The described processes make S(4)TdR an interesting candidate in the role of molecular probe for the detection of (1)O2 under different pH conditions.

Phototoxicity and cytotoxicity of chlorophyll a/cyclodextrins complexes on Jurkat cells.

The aggregation status of chlorophyll a (Chl a) and the ability of four cyclodextrins, hydroxypropyl-beta-cyclodextrin (HP-beta-CD), hydroxypropyl-gamma-cyclodextrin (HP-gamma-CD), heptakis(2,6-di-O-methyl)-beta-cyclodextrin (DIMEB), and heptakis(2,3,6-tri-O-methyl)-beta-cyclodextrin (TRIMEB), to solubilize the pigment in the complete cellular medium RPMI 1640 was estimated by means of UV-Vis absorption and static resonance light scattering (RLS) measurements. The results indicate that the pigment interacts with cyclodextrins in the cellular medium differently to that observed in water. The cytotoxic and phototoxic activity of these complexes towards human leukemia T-lymphocytes (Jurkat cells) was tested by means of experiments aimed to discriminate between the intrinsic toxicity and the toxicity induced by light. The overall data indicate that the HP-beta-CD is the cyclodextrins having the best characteristics to form with Chl a a potential supramolecular system for the photodynamic therapy.

Detailed investigation of ROS arisen from chlorophyll a/Chitosan based-biofilm.

The aim of this work is to study the nature of reactive oxygen species, ROS, arisen from Chitosan/2-HP-β-Cyclodextrin/Chlorophyll a (CH/CD/Chla) blended biofilm under a photodynamic activity. Suitable molecules, called primary acceptors, able to react selectively with ROS, in turn generated by the photosensitizer (PS), herein Chla, are used to attempt this purpose. The changes of the absorption and the emission spectra of these acceptors after the irradiation of aqueous solution containing the active biofilm have provided the specific nature of ROS and thus the main pathway of reaction followed by PS, in our condition. The (1)O2 formation was unveiled using Uric Acid (UA) and 9,10-diphenilanthracene (DPA). On the other hand, 2,7- dichlorofluorescin and Ferricytochrome c (Cyt-c) were used to detect the formation of hydrogen peroxide and superoxide radical anion, respectively. Results suggest that among the possible pathways of reaction, namely Type I and Type II, potentially followed by PSs, in our condition the hybrid biofilm CH/CD/Chla follows mainly Type II mechanism with the formation of (1)O2. However, the latter is involved in subsequent pathway of reaction involving Chla inducing, in addition, the formation of O2(-) and H2O2.

pH-related features and photostability of 4-thiothymidine in aqueous solution: an investigation by UV-visible, NMR and FTIR-ATR spectroscopies and by electrospray ionization mass spectrometry

The pH-related characteristics of 4-thiothymidine and its stability during prolonged exposure, at room temperature, to a neon lamp emitting in the 400–700 nm wavelength range were investigated by different spectroscopic techniques (UV-Vis, FTIR-ATR, 1H-NMR) and by ElectroSpray Ionization Mass Spectrometry (ESI-MS). The evaluation of the nucleoside photostability was performed as a control, with the perspective of studying its reactivity under the same conditions but in the presence of visible light-absorbing photosensitizers, able to generate reactive oxygen species. The comparison between UV-Vis spectra recorded at different pH values in the 7–12 range suggested the presence of an equilibrium related to the deprotonation of the N3–H group of 4-thiothymidine, with a pKa estimated to be close to 9. Some effects of the deprotonation occurring at alkaline pH were observed also in FTIR-ATR spectra, the main feature being the appearance of a band related to CN stretching, interpreted with the assumption of a partial double bond character by C2–N3, N3–C4 and C2–O− bonds, as a consequence of negative charge delocalization on the pyrimidine ring. As for photostability, UV-Vis, FTIR-ATR and NMR measurements suggested the generation of thymidine as a by-product but only after a prolonged (48 hours) irradiation time, whereas no significant alteration occurred in a shorter time range (1–2 hours), i.e. the one that will be considered in future studies involving the presence of photosensitizers. The nucleoside stability up to 2 hours of irradiation was confirmed by ESI-MS analyses; furthermore, on the other hand, the latter indicated the presence of three additional by-products, besides thymidine, after 48 hours of irradiation. In particular, an hydroxylated form of 4-thiothymidine and two dimeric species, characterized by S–S and S–O covalent bridges between two 4-thiothymidine and a 4-thiothymidine and a thymidine molecule, respectively, were detected.

One pot environmental friendly synthesis of gold nanoparticles using Punica Granatum Juice: A novel antioxidant agent for future dermatological and cosmetic applications

HYPOTHESIS The interesting properties of Gold Nanoparticles (AuNPs) make them attractive for different application fields such as cosmetology, medicine and clinical nanotechnologies. In this work a fast, easy and eco-friendly method for the AuNPs synthesis is proposed by using the Punica Granatum Juice (PGJ) with potential dermatological and cosmetic applications. The AuNPs antioxidant activity, due to the presence of phenols from the juice, and their use as booster for improving the Sun Protection Factor (SPF) in commercial sunscreen formulations, are thus expounded. EXPERIMENTS By using appropriate amounts of PGJ and HAuCl4, under mild work conditions, AuNPs with a mean size of 100 ± 40 nm are observed and carefully characterized. Solution pH, temperature, and volume were also changed for optimizing the AuNPs formation and features. The antioxidant activity was studied, by evaluating the AuNP ability of scavenging the radical 2,2-diphenyl-1-picrylhydrazylhydrate (DPPH). This finding was confirmed performing special experiments focused on the reaction between AuNPs and H2O2, by using suitable probes, such as 4-thiothymidine (S4TdR) and Cytochrome-c (Cyt-c). The SPF value was also calculated. FINDINGS The synthetized AuNPs showed a surface plasmon in visible range at 577 nm and resulted stable for long time in aqueous medium, also changing the pH values in the range 2-12. The studied antioxidant activity, confirmed also by performing special experiments with suitable probes, demonstrated the high performance of AuNPs. The AuNP photostability under sun irradiation is also shown. The calculated SPF values were in the range 3-18, related to AuNPs concentration in the range 1.80 × 10-12-1.00 × 10-11 M. The same AuNPs concentrations were used for cellular experiments. Indeed, since the AuNPs-PGJ mediated will be potentially introduced by dermal contact, dermal fibroblasts (Human Dermal Fibroblasts, HDF) and Human Microvascular Endothelial Cells (HMVEC) were used to evaluate the possible effects of these nanoparticles as a preliminary step. The results indicated that an AuNP concentrations in the range 1.80 × 10-12-3.60 × 10-12 M could be adopted since they do not appeared cyctotoxic.