Elena Vismara

Surface functionalization of cotton cellulose with glycidyl methacrylate and its application for the adsorption of aromatic pollutants from wastewaters

Cellulose material C1 was prepared by grafting of glycidyl methacrylate (GMA) in the presence of Fenton-type reagent. This one-pot procedure provided C1 with glycidyl isobutyrate branches. Glycidyl epoxide ring opening with water turned C1-C2 material branched with glycerol isobutyrate. So, C1 surface bears hydrophobic branches ending with the glycidyl group, while C2 surface presents hydrophilic branches ending with the glycerol group. The adsorption of aromatic polluting substances like phenol (Ph), 4-nitrophenol (pNPh), 2,4-dinitrophenol (dNPh), 2,4,6-trinitrophenol (picric acid, tNPh) and 2-naphtol (BN) from their water solutions was tested with C1, C2 and with the untreated cellulose material C0. Phenol adsorption did not occur. All the other aromatic molecules were removed in different amount both by C1 and C2. C1 and C2 showed different affinities towards nitrophenols and 2-naphtol. While C1 was much more effective for removing the hydrophobic 2-naphtol, C2 had higher adsorption capacity towards the hydrophilic nitrophenols, in agreement with their branches polarity, respectively.

Heparin and carboxymethylchitosan metal nanoparticles: an evaluation of their cytotoxicity.

In the search for noninvasive diagnostic techniques and new therapies, “nanosystems”, which are capable of binding and targeting bioactive molecules, are becoming increasingly important. In this context, biocompatible coatings are gaining interest, not only for their biological effects but also because they are considered capable to mask nanoparticle toxicity. In this work, we have compared the toxicity of nanoparticles coated with heparin and carboxymethylchitosan in the SKOV-3 cell line. Our results indicate that heparin and carboxymethylchitosan coatings do not guarantee the decrease of nanoparticle intrinsic toxicity which is often envisaged. Nonetheless, these coatings provide the opportunity for further functionalization with a variety of biomolecules for their use in theranostics.

Glycomimetics via a new glycoexoenitols–malonyl radical C–C bond formation

C-Glycosyl methylenemalonates 2 and 4, useful precursors for the synthesis of glycopeptides and glycoproteins mimics, are obtained by reaction of a malonyl radical on the glycoexoenitols 1 and 3; reaction of the same radical with 6-deoxy-1,2:3,4-di-O-isopropylidene-β-L-arabino- hex-5-enopyranose 5 results in a mixture of the malonylderivatives 6, 7 and 8 and, in diluted THF solutions, also in the tetrahydrofuranyl derivative 9.

Synthesis of Stable Analogues of Glyceroglycolipids

Abstract Stable C-glycosidic analogues of 2-O-(β-D-glucopyranosyl)-sn-glycerol (1a), 2-O-(β-D-galactopyranosyl)-sn-glycerol (1b), 1-O-(β-D-glucopyranosyl)-sn-glycerol (7) and their dipalmitoyl ester have been synthesised starting from the corresponding 2,3,4,6-tetra-O-benzyl-glyconolactones 9. The 2-O-derivatives 1 were obtained by methylenation of the lactone 9, reaction of the obtained glycoexoenitol 10 with a malonyl radical, reduction of the malonyl derivative 11 and deprotection. The 1-O-derivative 7 was obtained by reaction of the lactone 9 with butenylmagnesium bromide, reduction of the obtained lactol 14, osmylation and deprotection.

Posidonia oceanica as a Renewable Lignocellulosic Biomass for the Synthesis of Cellulose Acetate and Glycidyl Methacrylate Grafted Cellulose

High-grade cellulose (97% α-cellulose content) of 48% crystallinity index was extracted from the renewable marine biomass waste Posidonia oceanica using H2O2 and organic peracids following an environmentally friendly and chlorine-free process. This cellulose appeared as a new high-grade cellulose of waste origin quite similar to the high-grade cellulose extracted from more noble starting materials like wood and cotton linters. The benefits of α-cellulose recovery from P. oceanica were enhanced by its transformation into cellulose acetate CA and cellulose derivative GMA-C. Fully acetylated CA was prepared by conventional acetylation method and easily transformed into a transparent film. GMA-C with a molar substitution (MS) of 0.72 was produced by quenching Fenton’s reagent (H2O2/FeSO4) generated cellulose radicals with GMA. GMA grafting endowed high-grade cellulose from Posidonia with adsorption capability. GMA-C removes β-naphthol from water with an efficiency of 47%, as measured by UV-Vis spectroscopy. After hydrolysis of the glycidyl group to glycerol group, the modified GMA-C was able to remove p-nitrophenol from water with an efficiency of 92%, as measured by UV-Vis spectroscopy. α-cellulose and GMA-Cs from Posidonia waste can be considered as new materials of potential industrial and environmental interest.

Non-Covalent Synthesis of Metal Oxide Nanoparticle–Heparin Hybrid Systems: A New Approach to Bioactive Nanoparticles

Heparin has been conjugated to Fe3O4, Co3O4, and NiO nanoparticles (NPs) through electrostatic interactions, producing colloidal suspensions of hybrid metal oxide heparin NPs that are stable in water. Negative zeta potentials and retention of heparin’s ability to capture toluidine blue indicate that heparin’s negative charges are exposed on the surface of the coated NPs. IR results confirmed the formation of nanohybrids as did NMR experiments, which were also interpreted on the basis of toluidine blue tests. Transmission electron microscopy results revealed that the heparin coating does not modify the shape or dimension of the NPs. Dynamic light scattering and negative zeta potential measurements confirmed that heparin surface functionalisation is an effective strategy to prevent NP aggregation.

An Esr Approach To Hypervalent Iodine Induced Iododecarboxylation

Some mechanistic considerations based on the results of an ESR spectroscopic study of the IBDA (iodosobenzene diacetate) induced iododecarboxylation of several aliphatic carboxylic acids are reported. Both acetoxy units in IBDA are replaced by carboxylate groups in the first step of the reaction, forming a hypervalent iodine complex which then undergoes homolytic photodegradation. The R. radicals deriving from decarboxylation of the starting acids have been trapped by means of thiobenzoyl triphenylsilane and identified using ESR spectroscopy.

Anti-metastatic semi-synthetic sulfated maltotriose C-C linked dimers. Synthesis and characterisation.

This manuscript describes the preparation and the spectroscopic characterisation of semi-synthetic sulfated maltotriose C-C linked dimers (SMTCs) where the natural C-O-C anomeric bond was substituted by one direct central C-C bond. This C-C bond induces conformation and flexibility changes with respect to the usual anomeric bond. SMTCs neutral precursors came from maltotriosyl bromide electroreduction through maltotriosyl radical intermediate dimerisation. The new C-C bond configuration, named for convenience α,α, α,β and β,β as the natural anomeric bond, dictated the statistic ratio formation of three diastereoisomers. They were separated by silica gel flash chromatography followed by semi preparative HPLC chromatography. Each diastereoisomer was exhaustively sulfated to afford the corresponding SMTCs. SMTCs were huge characterised by NMR spectroscopy which provided the sulfation degree, too. α,α and α,β were found quite homogeneous samples with a high degree of sulfation (85–95%). β,β appeared a non-homogeneous sample whose average sulfation degree was evaluated at around 78%. Mass spectroscopy experiments confirmed the sulfation degree range. Some considerations were proposed about SMTCs structure-biological properties.

Electrochemical reduction of halogenosugars on silver: a new approach to C-disaccharide-like mimics

Electrochemical reduction on silver of tri-O-acetyl-α-D-fucopyranosyl bromide 3 affords (1 → 1′)-linked C-disaccharide-like mimics 6–8; reduction of 1,2:3,4-di-O-isopropylidene-6-deoxy-6-iodo-α-D-galactopyranose 5 provides 1,2:3,4-di-O-isopropylidene-6-deoxy-6-(1′,2′ : 3′,4′-di-O-isopropylidene-6′-deoxy-α-D-galactopyranos-6′-yl)-α-D-galactopyranose 9; simultaneous reduction of 5 and tetra-O-acetyl-α-D-glucopyranosyl bromide 1 or tri-O-acetyl-α-L-fucopyranosyl bromide 4 gives 9 and methylene-bridged C-disaccharide-like mimics 11, 12 or 13, 14, respectively.

Self-Assembled Lipid Nanoparticles for Oral Delivery of Heparin-Coated Iron Oxide Nanoparticles for Theranostic Purposes

Recently, solid lipid nanoparticles (SLNs) have attracted increasing attention owing to their potential as an oral delivery system, promoting intestinal absorption in the lymphatic circulation which plays a role in disseminating metastatic cancer cells and infectious agents throughout the body. SLN features can be exploited for the oral delivery of theranostics. Therefore, the aim of this work was to design and characterise self-assembled lipid nanoparticles (SALNs) to encapsulate and stabilise iron oxide nanoparticles non-covalently coated with heparin (Fe@hepa) as a model of a theranostic tool. SALNs were characterised for physico-chemical properties (particle size, surface charge, encapsulation efficiency, in vitro stability, and heparin leakage), as well as in vitro cytotoxicity by methyl thiazole tetrazolium (MTT) assay and cell internalisation in CaCo-2, a cell line model used as an indirect indication of intestinal lymphatic absorption. SALNs of about 180 nm, which are stable in suspension and have a high encapsulation efficiency (>90%) were obtained. SALNs were able to stabilise the heparin coating of Fe@hepa, which are typically unstable in physiological environments. Moreover, SALNs–Fe@hepa showed no cytotoxicity, although their ability to be internalised into CaCo-2 cells was highlighted by confocal microscopy analysis. Therefore, the results indicated that SALNs can be considered as a promising tool to orally deliver theranostic Fe@hepa into the lymphatic circulation, although further in vivo studies are needed to comprehend further potential applications.