A new model for prediction of mutual diffusion coefficients is proposed over the whole compositio... more A new model for prediction of mutual diffusion coefficients is proposed over the whole composition range for binary liquid systems of one self-associating component and one non-polar component. The model is based on the Darken equation with the knowledge of intra-diffusion coefficients at infinite dilution of both species and viscosity data for the system, and takes into account the cluster diffusion approach with a scaling power on the thermodynamic correction factor. The model was validated to show good concurrence with the experimental mutual diffusion data. Following the analysis that the mutual diffusion coefficients at infinite dilution can be identified with the molecular intra-diffusion coefficient of the species (i.e., the intra-diffusion coefficient at infinite dilution in absence of self-association), the proposed equation was extended to binary liquid systems without significant association, though the accuracy in prediction for systems of cross associating species may be limited. The model relies on the knowledge of the viscosity of the mixture over the whole composition range and may be used as a valid alternative to models based on measuring intra-diffusion coefficients as a function of composition. Indeed, such data are not always available or are more difficult to obtain whereas viscosity measurements can be readily available and more easily measured.
Based on compelling preclinical evidence concerning the progress of our novel ruthenium-based met... more Based on compelling preclinical evidence concerning the progress of our novel ruthenium-based metallotherapeutics, we are focusing research efforts on challenging indications for the treatment of invasive neoplasms such as the triple-negative breast cancer (TNBC). This malignancy mainly afflicts younger women, who are black, or who have a BRCA1 mutation. Because of faster growing and spreading, TNBC differs from other invasive breast cancers having fewer treatment options and worse prognosis, where existing therapies are mostly ineffective, resulting in a large unmet biomedical need. In this context, we benefited from an experimental model of TNBC both in vitro and in vivo to explore the effects of a biocompatible cationic liposomal nanoformulation, named HoThyRu/DOTAP, able to effectively deliver the antiproliferative ruthenium(III) complex AziRu, thus resulting in a prospective candidate drug. As part of the multitargeting mechanisms featuring metal-based therapeutics other than p...
Ruthenium(III) complexes are very promising candidates as metal-based anticancer drugs, and sever... more Ruthenium(III) complexes are very promising candidates as metal-based anticancer drugs, and several studies have supported the likely role of human serum proteins in the transport and selective delivery of Ru(III)-based compounds to tumor cells. Herein, the anticancer nanosystem composed of an amphiphilic nucleolipid incorporating a Ru(III) complex, which we named DoHuRu, embedded into the biocompatible cationic lipid DOTAP, was investigated as to its interaction with two human serum proteins thought to be involved in the mechanism of action of Ru(III)-based anticancer drugs, i.e., human serum albumin (HSA) and human transferrin (hTf). This nanosystem was studied in comparison with the simple Ru(III) complex named AziRu, a low molecular weight metal complex previously designed as an analogue of NAMI-A, decorated with the same ruthenium ligands as DoHuRu but devoid of the nucleolipid scaffold and not inserted in liposomal formulations. For this study, different spectroscopic techniqu...
With the aim of developing a new approach to obtain improved aptamers, a cyclic thrombin‐binding ... more With the aim of developing a new approach to obtain improved aptamers, a cyclic thrombin‐binding aptamer (TBA) analogue (cycTBA) has been prepared by exploiting a copper(I)‐assisted azide–alkyne cycloaddition. The markedly increased serum resistance and exceptional thermal stability of the G‐quadruplex versus TBA were associated with halved thrombin inhibition, which suggested that some flexibility in the TBA structure was necessary for protein recognition.
The Ru III-based prodrug AziRu efficiently binds to proteins, but the mechanism of its release is... more The Ru III-based prodrug AziRu efficiently binds to proteins, but the mechanism of its release is still disputed. Herein, in order to test the hypothesis of a reduction-mediated Ru release from proteins, a Raman-assisted crystallographic study on AziRu binding to a model protein (hen egg white lysozyme), in two different oxidation states, Ru II and Ru III , was carried out. Our results indicate Ru reduction, but the Ru release upon reduction is dependent on the reducing agent. To better understand this process, a pH-dependent, spectroelectrochemical surface-enhanced Raman scattering (SERS) study was performed also on AziRu-functionalized Au electrodes as a surrogate and simplest model system of Ru II-and Ru III-based drugs. This SERS study provided a pK a of 6.0 ± 0.4 for aquated AziRu in the Ru III state, which falls in the watershed range of pH values separating most cancer environments from their physiological counterparts. These experiments also indicate a dramatic shift of the redox potential E 0 by >600 mV of aquated AziRu toward more positive potentials upon acidification, suggesting a selective AziRu reduction in cancer lumen but not in healthy ones. It is expected that the nature of the ligands (e.g., pyridine vs imidazole, present in well-known Ru III complex NAMI-A) will modulate the pK a and E 0 , without affecting the underlying reaction mechanism.
Physical chemistry chemical physics : PCCP, Jan 27, 2018
Diffusion plays a central part in many unit operations. The Maxwell-Stefan model is the dominant ... more Diffusion plays a central part in many unit operations. The Maxwell-Stefan model is the dominant model for both gaseous and liquid diffusion. However, it was developed from the kinetic theory of gases, raising the question of whether it can be extended to non-ideal liquid systems. The dynamic fluctuation model is an alternative model based on the Cussler theory and predicts a smaller thermodynamic influence relative to the linear influence of the Maxwell-Stefan model due to dynamic concentration fluctuations. Since the dynamic fluctuation model, which uses the scaling factor α, had improved performance relative to the Maxwell-Stefan model for a wide range of binary systems, it is postulated that this improved performance should also be observed for a ternary system. In this work, the dynamic molecular fluctuation model was extended to a highly non-ideal ternary system, using the same scaling factor α, through matrix manipulation. Using self-diffusion data measured by NMR, mutual dif...
Ruthenium complexes are attracting increasing attention as second‐generation metal‐based anticanc... more Ruthenium complexes are attracting increasing attention as second‐generation metal‐based anticancer agents, with NAMI‐A and KP1019 as the major representatives of this class having undergone clinical trials. Our recent interest has been focused on the synthesis and characterization of new amphiphilic derivatives of nucleosides (nucleolipids). These compounds have been selected as core scaffolds linked to RuIII complexes and capable of self‐assembly into stable nanostructures in aq. solutions so to transport the metal ions efficiently into the cell. Through the use of ribo‐ and deoxyribonucleosides as starting building blocks, a mini‐library of nucleolipidic RuIII complexes decorated with diverse hydrophilic and lipophilic chains and incorporating the NAMI‐A analogue AziRu has been prepared. When co‐aggregated with biocompatible lipids, these RuIII‐containing nucleolipids proved to be stable for months under physiological conditions. Detailed microstructural characterization, carried...
Liposomes are complex aggregates, often including polyethylene glycol (PEG) to expand their life ... more Liposomes are complex aggregates, often including polyethylene glycol (PEG) to expand their life span in vivo, although their full biocompatibility is still questioned. With the aim to suitably replace PEG within liposomal formulations, here we propose a new liposomes formulation, which includes an amphiphilic molecule of natural origin: the lipooligosaccharide (LOS) from the Gram‐negative bacterium Rhizobium rubi. LOS architecture is bifunctional: the lipid moiety at one terminus promotes its insertion into the liposome, the other terminus is hydrophilic and in this case presents an oligosaccharide motif similar to the human Lewis B antigen. Liposomes were prepared by co‐formulating de‐O‐acylated LOS (de‐LOS) with the lipid 1‐palmitoyl‐2‐oleoyl‐sn‐glycero‐3‐phosphocholine (POPC) and the anticancer nucleolipid‐based Ru(III) complex, ToThyRu. In‐depth microstructural characterization shows that de‐LOS containing liposomes are stable aggregates. In vitro preliminary bioscreens have di...
Superparamagnetic Iron Oxide Nanoparticles (SPIONs) are performing contrast agents for Magnetic R... more Superparamagnetic Iron Oxide Nanoparticles (SPIONs) are performing contrast agents for Magnetic Resonance Imaging (MRI).
The anticancer Ru(iii) complex AziRu was studied in its interaction with model single stranded an... more The anticancer Ru(iii) complex AziRu was studied in its interaction with model single stranded and duplex oligonucleotides in comparison with its analogue NAMI-A, currently in advanced clinical trials, using UV-vis, CD and ESI-MS techniques.
Journal of colloid and interface science, Jan 15, 2015
Nanostructured hydrogels composed by biocompatible molecules are formulated and characterized. Th... more Nanostructured hydrogels composed by biocompatible molecules are formulated and characterized. They are based on a polymer network formed by hydrophobically modified chitosans (HMCHIT or CnCHIT) in which vesicles of monoolein (MO) and oleic acid or sodium oleate (NaO), depending on pH, are embedded. The best conditions for gel formation, in terms of pH, length of the hydrophobic moieties of chitosan, and weight proportion among the three components were estimated by visual inspection of a large number of samples. Among all possible combinations, the system C12CHIT-MO-NaO in the weight proportion (1:1:1) is optimal for the formation of a well-structured gel-like system, which is also confirmed by rheological experiments. Electron paramagnetic resonance (EPR) measurements unambiguously show the presence of lipid bilayers in this mixture, indicating that MO-NaO vesicles are stabilized by C12CHIT even at acid pH. A wide small angle neutron scattering investigation performed on several t...
A detailed structural investigation on mixed micelle aggregates as target-specific contrast agent... more A detailed structural investigation on mixed micelle aggregates as target-specific contrast agents for magnetic resonance imaging technique has been carried out by way of small angle neutron scattering measurements. These mixed micelles are formed by two new amphiphilic molecules formed by a bioactive peptide and a claw moiety. The first molecule, C 18 H 37 CONH(AdOO) x-G-CCK8 (C18LxCCK8, x) 2, 5), contains an 18carbon-atom alkylic chain bound to the C-terminal of the cholecystokinin octapeptide amide (CCK 26-33 or CCK8) and is able to bind to the overexpressed CCK receptor of some tumor cells. The second molecule, C 18 H 37 CONHLys(DTPAGlu)CONH 2 5-(C18DTPAGlu) or its gadolinium complex [C 18 H 37 CONHLys(DTPAGlu)-CONH 2 Gd] 2-, C18DTPAGlu(Gd), contains the same 18-carbon-atom alkylic chain bound, through a lysine residue, to the DTPAGlu chelating agent. Small angle neutron scattering measurements have been performed on ternary systems at different total concentrations and at various ratios of the two molecules. The effect of the concentration on the aggregation number as well as on the shape of the micelle has been investigated. Furthermore in order to optimize the exposure of the peptide on the micelle surface, C18LxCCK8 having the spacer L of different length has been used. The pure binary systems of the synthesized molecules are also presented.
The transport properties of NaCl in poly(ethylene glycol)-water (PEG-water) mixtures are presente... more The transport properties of NaCl in poly(ethylene glycol)-water (PEG-water) mixtures are presented, with special regard to the dielectric and hydrodynamic effects. We report experimental data of mutual diffusion, viscosity, and conductivity for the aqueous ternary system containing PEG with an average molecular weight of 2000 a.m.u. (PEG2000, component 1) and sodium chloride (NaCl, component 2). Both PEG2000 and NaCl are used extensively as protein-crystallizing agents. The four diffusion coefficients (D 11 , D 12 , D 21 , and D 22) that are required to describe the diffusive properties of a ternary system correctly were determined by the precise Gouy interferometric method. We also report measurements of the dielectric constant for several aqueous binary systems containing PEG with three different molecular weights (200, 400, and 2000 a.m.u.), which significantly decreases the dielectric constant of aqueous solutions. The experimental values of the four diffusion coefficients are discussed in terms of obstruction, excluded volume, and dielectric effects. The dependence of the PEG main-term diffusion coefficient, D 11 , on the salt concentration is quantitatively described by the corresponding change of viscosity. The cross-term diffusion coefficients, D 12 and D 21 , are described in terms of excluded volume effects and PEG-salt nonpreferential interactions. The dependence of the salt main term diffusion coefficient, D 22 , on PEG concentration is essentially due to obstruction effects. Moreover, a remarkable agreement between D 22 and the salt equivalent conductivity has been determined. This correlation suggests that, even though the dielectric constant significantly changes in the presence of PEG, the electrostatic ion-ion interactions (the summation of the extent of ion-pairing and electrophoretic contributions) are not significantly modified by the polymer. This analysis of the diffusive and conductivity properties of electrolytes in the presence of PEG have allowed us to clarify important aspects of the electrostatic properties of aqueous PEG-salt systems and supplies valuable information for salt properties in "mixed solvents". A useful classification of mixed solvents is proposed, distinguishing between "viscous" and "dielectric" mixed solvents.
Selectivity and efficacy towards target cancer cells, as well as biocompatibility, are current ch... more Selectivity and efficacy towards target cancer cells, as well as biocompatibility, are current challenges of advanced chemotherapy powering the discovery of unconventional metal-based drugs and the search for novel therapeutic approaches. Among second-generation metal-based chemotherapeutics, ruthenium complexes have demonstrated promising anticancer activity coupled to minimal toxicity profiles and peculiar biochemical features. In this context, our research group has recently focused on a bioactive Ru(III) complex—named AziRu—incorporated into a suite of ad hoc designed nucleolipid nanosystems to ensure its chemical stability and delivery. Indeed, we proved that the structure and properties of decorated nucleolipids can have a major impact on the anticancer activity of the ruthenium core. Moving in this direction, here we describe a preclinical study performed by a mouse xenograft model of human breast cancer to establish safety and efficacy in vivo of a cationic Ru(III)-based nuc...
Nanoparticles (NPs) are increasingly exploited as diagnostic and therapeutic devices in medicine.... more Nanoparticles (NPs) are increasingly exploited as diagnostic and therapeutic devices in medicine. Among them, superparamagnetic nanoparticles (SPIONs) represent very promising tools for magnetic resonance imaging, local heaters for hyperthermia, and nanoplatforms for multimodal imaging and theranostics. However, the use of NPs, including SPIONs, in medicine presents several issues: first, the encounter with the biological world and proteins in particular. Indeed, nanoparticles can suffer from protein adsorption, which can affect NP functionality and biocompatibility. In this respect, we have investigated the interaction of small SPIONs covered by an amphiphilic double layer of oleic acid/oleylamine and 1octadecanoyl-sn-glycero-3-phosphocholine with two abundant human plasma proteins, human serum albumin (HSA) and human transferrin. By means of spectroscopic and scattering techniques, we analyzed the effect of SPIONs on protein structure and the binding affinities, and only found strong binding in the case of HSA. In no case did SPIONs alter the protein structure significantly. We structurally characterized HSA/SPIONs complexes by means of light and neutron scattering, highlighting the formation of a monolayer of protein molecules on the NP surface. Their interaction with lipid bilayers mimicking biological membranes was investigated by means of neutron reflectivity. We show that HSA/SPIONs do not affect lipid bilayer features and could be further exploited as a nanoplatform for future applications. Overall, our findings point toward a high biocompatibility of phosphocholine-decorated SPIONs and support their use in nanomedicine.
Water-in-oil (W/O) nanoemulsions stabilized by phospholipids (PLs) are increasingly exploited in ... more Water-in-oil (W/O) nanoemulsions stabilized by phospholipids (PLs) are increasingly exploited in a wide spectrum of applications, from pharmaceuticals to food and cosmetic formulations. In this work, we report the design and optimization of an innovative emulsion based on a mixture of phosphoethanolamine (PE) and phosphoglycerol (PG) PLs, inspired by the composition of the inner leaflet of a bacterial outer membrane. Using the natural oil squalene as the continuous organic phase, no additional emulsion stabilizer is needed. On the other hand, a small amount of Span 80 is required when dodecane is used. The obtained nanoemulsions are stable for at least two hours, thus allowing the droplet size and distribution to be characterized by Dynamic Light Scattering (DLS) and the lipid layer structure and dynamics to be analyzed by Electron Paramagnetic Resonance (EPR) spectroscopy. The results indicate that squalene shallowly intercalates among the lipid tail termini, being unable to deeply...
A new model for prediction of mutual diffusion coefficients is proposed over the whole compositio... more A new model for prediction of mutual diffusion coefficients is proposed over the whole composition range for binary liquid systems of one self-associating component and one non-polar component. The model is based on the Darken equation with the knowledge of intra-diffusion coefficients at infinite dilution of both species and viscosity data for the system, and takes into account the cluster diffusion approach with a scaling power on the thermodynamic correction factor. The model was validated to show good concurrence with the experimental mutual diffusion data. Following the analysis that the mutual diffusion coefficients at infinite dilution can be identified with the molecular intra-diffusion coefficient of the species (i.e., the intra-diffusion coefficient at infinite dilution in absence of self-association), the proposed equation was extended to binary liquid systems without significant association, though the accuracy in prediction for systems of cross associating species may be limited. The model relies on the knowledge of the viscosity of the mixture over the whole composition range and may be used as a valid alternative to models based on measuring intra-diffusion coefficients as a function of composition. Indeed, such data are not always available or are more difficult to obtain whereas viscosity measurements can be readily available and more easily measured.
Based on compelling preclinical evidence concerning the progress of our novel ruthenium-based met... more Based on compelling preclinical evidence concerning the progress of our novel ruthenium-based metallotherapeutics, we are focusing research efforts on challenging indications for the treatment of invasive neoplasms such as the triple-negative breast cancer (TNBC). This malignancy mainly afflicts younger women, who are black, or who have a BRCA1 mutation. Because of faster growing and spreading, TNBC differs from other invasive breast cancers having fewer treatment options and worse prognosis, where existing therapies are mostly ineffective, resulting in a large unmet biomedical need. In this context, we benefited from an experimental model of TNBC both in vitro and in vivo to explore the effects of a biocompatible cationic liposomal nanoformulation, named HoThyRu/DOTAP, able to effectively deliver the antiproliferative ruthenium(III) complex AziRu, thus resulting in a prospective candidate drug. As part of the multitargeting mechanisms featuring metal-based therapeutics other than p...
Ruthenium(III) complexes are very promising candidates as metal-based anticancer drugs, and sever... more Ruthenium(III) complexes are very promising candidates as metal-based anticancer drugs, and several studies have supported the likely role of human serum proteins in the transport and selective delivery of Ru(III)-based compounds to tumor cells. Herein, the anticancer nanosystem composed of an amphiphilic nucleolipid incorporating a Ru(III) complex, which we named DoHuRu, embedded into the biocompatible cationic lipid DOTAP, was investigated as to its interaction with two human serum proteins thought to be involved in the mechanism of action of Ru(III)-based anticancer drugs, i.e., human serum albumin (HSA) and human transferrin (hTf). This nanosystem was studied in comparison with the simple Ru(III) complex named AziRu, a low molecular weight metal complex previously designed as an analogue of NAMI-A, decorated with the same ruthenium ligands as DoHuRu but devoid of the nucleolipid scaffold and not inserted in liposomal formulations. For this study, different spectroscopic techniqu...
With the aim of developing a new approach to obtain improved aptamers, a cyclic thrombin‐binding ... more With the aim of developing a new approach to obtain improved aptamers, a cyclic thrombin‐binding aptamer (TBA) analogue (cycTBA) has been prepared by exploiting a copper(I)‐assisted azide–alkyne cycloaddition. The markedly increased serum resistance and exceptional thermal stability of the G‐quadruplex versus TBA were associated with halved thrombin inhibition, which suggested that some flexibility in the TBA structure was necessary for protein recognition.
The Ru III-based prodrug AziRu efficiently binds to proteins, but the mechanism of its release is... more The Ru III-based prodrug AziRu efficiently binds to proteins, but the mechanism of its release is still disputed. Herein, in order to test the hypothesis of a reduction-mediated Ru release from proteins, a Raman-assisted crystallographic study on AziRu binding to a model protein (hen egg white lysozyme), in two different oxidation states, Ru II and Ru III , was carried out. Our results indicate Ru reduction, but the Ru release upon reduction is dependent on the reducing agent. To better understand this process, a pH-dependent, spectroelectrochemical surface-enhanced Raman scattering (SERS) study was performed also on AziRu-functionalized Au electrodes as a surrogate and simplest model system of Ru II-and Ru III-based drugs. This SERS study provided a pK a of 6.0 ± 0.4 for aquated AziRu in the Ru III state, which falls in the watershed range of pH values separating most cancer environments from their physiological counterparts. These experiments also indicate a dramatic shift of the redox potential E 0 by >600 mV of aquated AziRu toward more positive potentials upon acidification, suggesting a selective AziRu reduction in cancer lumen but not in healthy ones. It is expected that the nature of the ligands (e.g., pyridine vs imidazole, present in well-known Ru III complex NAMI-A) will modulate the pK a and E 0 , without affecting the underlying reaction mechanism.
Physical chemistry chemical physics : PCCP, Jan 27, 2018
Diffusion plays a central part in many unit operations. The Maxwell-Stefan model is the dominant ... more Diffusion plays a central part in many unit operations. The Maxwell-Stefan model is the dominant model for both gaseous and liquid diffusion. However, it was developed from the kinetic theory of gases, raising the question of whether it can be extended to non-ideal liquid systems. The dynamic fluctuation model is an alternative model based on the Cussler theory and predicts a smaller thermodynamic influence relative to the linear influence of the Maxwell-Stefan model due to dynamic concentration fluctuations. Since the dynamic fluctuation model, which uses the scaling factor α, had improved performance relative to the Maxwell-Stefan model for a wide range of binary systems, it is postulated that this improved performance should also be observed for a ternary system. In this work, the dynamic molecular fluctuation model was extended to a highly non-ideal ternary system, using the same scaling factor α, through matrix manipulation. Using self-diffusion data measured by NMR, mutual dif...
Ruthenium complexes are attracting increasing attention as second‐generation metal‐based anticanc... more Ruthenium complexes are attracting increasing attention as second‐generation metal‐based anticancer agents, with NAMI‐A and KP1019 as the major representatives of this class having undergone clinical trials. Our recent interest has been focused on the synthesis and characterization of new amphiphilic derivatives of nucleosides (nucleolipids). These compounds have been selected as core scaffolds linked to RuIII complexes and capable of self‐assembly into stable nanostructures in aq. solutions so to transport the metal ions efficiently into the cell. Through the use of ribo‐ and deoxyribonucleosides as starting building blocks, a mini‐library of nucleolipidic RuIII complexes decorated with diverse hydrophilic and lipophilic chains and incorporating the NAMI‐A analogue AziRu has been prepared. When co‐aggregated with biocompatible lipids, these RuIII‐containing nucleolipids proved to be stable for months under physiological conditions. Detailed microstructural characterization, carried...
Liposomes are complex aggregates, often including polyethylene glycol (PEG) to expand their life ... more Liposomes are complex aggregates, often including polyethylene glycol (PEG) to expand their life span in vivo, although their full biocompatibility is still questioned. With the aim to suitably replace PEG within liposomal formulations, here we propose a new liposomes formulation, which includes an amphiphilic molecule of natural origin: the lipooligosaccharide (LOS) from the Gram‐negative bacterium Rhizobium rubi. LOS architecture is bifunctional: the lipid moiety at one terminus promotes its insertion into the liposome, the other terminus is hydrophilic and in this case presents an oligosaccharide motif similar to the human Lewis B antigen. Liposomes were prepared by co‐formulating de‐O‐acylated LOS (de‐LOS) with the lipid 1‐palmitoyl‐2‐oleoyl‐sn‐glycero‐3‐phosphocholine (POPC) and the anticancer nucleolipid‐based Ru(III) complex, ToThyRu. In‐depth microstructural characterization shows that de‐LOS containing liposomes are stable aggregates. In vitro preliminary bioscreens have di...
Superparamagnetic Iron Oxide Nanoparticles (SPIONs) are performing contrast agents for Magnetic R... more Superparamagnetic Iron Oxide Nanoparticles (SPIONs) are performing contrast agents for Magnetic Resonance Imaging (MRI).
The anticancer Ru(iii) complex AziRu was studied in its interaction with model single stranded an... more The anticancer Ru(iii) complex AziRu was studied in its interaction with model single stranded and duplex oligonucleotides in comparison with its analogue NAMI-A, currently in advanced clinical trials, using UV-vis, CD and ESI-MS techniques.
Journal of colloid and interface science, Jan 15, 2015
Nanostructured hydrogels composed by biocompatible molecules are formulated and characterized. Th... more Nanostructured hydrogels composed by biocompatible molecules are formulated and characterized. They are based on a polymer network formed by hydrophobically modified chitosans (HMCHIT or CnCHIT) in which vesicles of monoolein (MO) and oleic acid or sodium oleate (NaO), depending on pH, are embedded. The best conditions for gel formation, in terms of pH, length of the hydrophobic moieties of chitosan, and weight proportion among the three components were estimated by visual inspection of a large number of samples. Among all possible combinations, the system C12CHIT-MO-NaO in the weight proportion (1:1:1) is optimal for the formation of a well-structured gel-like system, which is also confirmed by rheological experiments. Electron paramagnetic resonance (EPR) measurements unambiguously show the presence of lipid bilayers in this mixture, indicating that MO-NaO vesicles are stabilized by C12CHIT even at acid pH. A wide small angle neutron scattering investigation performed on several t...
A detailed structural investigation on mixed micelle aggregates as target-specific contrast agent... more A detailed structural investigation on mixed micelle aggregates as target-specific contrast agents for magnetic resonance imaging technique has been carried out by way of small angle neutron scattering measurements. These mixed micelles are formed by two new amphiphilic molecules formed by a bioactive peptide and a claw moiety. The first molecule, C 18 H 37 CONH(AdOO) x-G-CCK8 (C18LxCCK8, x) 2, 5), contains an 18carbon-atom alkylic chain bound to the C-terminal of the cholecystokinin octapeptide amide (CCK 26-33 or CCK8) and is able to bind to the overexpressed CCK receptor of some tumor cells. The second molecule, C 18 H 37 CONHLys(DTPAGlu)CONH 2 5-(C18DTPAGlu) or its gadolinium complex [C 18 H 37 CONHLys(DTPAGlu)-CONH 2 Gd] 2-, C18DTPAGlu(Gd), contains the same 18-carbon-atom alkylic chain bound, through a lysine residue, to the DTPAGlu chelating agent. Small angle neutron scattering measurements have been performed on ternary systems at different total concentrations and at various ratios of the two molecules. The effect of the concentration on the aggregation number as well as on the shape of the micelle has been investigated. Furthermore in order to optimize the exposure of the peptide on the micelle surface, C18LxCCK8 having the spacer L of different length has been used. The pure binary systems of the synthesized molecules are also presented.
The transport properties of NaCl in poly(ethylene glycol)-water (PEG-water) mixtures are presente... more The transport properties of NaCl in poly(ethylene glycol)-water (PEG-water) mixtures are presented, with special regard to the dielectric and hydrodynamic effects. We report experimental data of mutual diffusion, viscosity, and conductivity for the aqueous ternary system containing PEG with an average molecular weight of 2000 a.m.u. (PEG2000, component 1) and sodium chloride (NaCl, component 2). Both PEG2000 and NaCl are used extensively as protein-crystallizing agents. The four diffusion coefficients (D 11 , D 12 , D 21 , and D 22) that are required to describe the diffusive properties of a ternary system correctly were determined by the precise Gouy interferometric method. We also report measurements of the dielectric constant for several aqueous binary systems containing PEG with three different molecular weights (200, 400, and 2000 a.m.u.), which significantly decreases the dielectric constant of aqueous solutions. The experimental values of the four diffusion coefficients are discussed in terms of obstruction, excluded volume, and dielectric effects. The dependence of the PEG main-term diffusion coefficient, D 11 , on the salt concentration is quantitatively described by the corresponding change of viscosity. The cross-term diffusion coefficients, D 12 and D 21 , are described in terms of excluded volume effects and PEG-salt nonpreferential interactions. The dependence of the salt main term diffusion coefficient, D 22 , on PEG concentration is essentially due to obstruction effects. Moreover, a remarkable agreement between D 22 and the salt equivalent conductivity has been determined. This correlation suggests that, even though the dielectric constant significantly changes in the presence of PEG, the electrostatic ion-ion interactions (the summation of the extent of ion-pairing and electrophoretic contributions) are not significantly modified by the polymer. This analysis of the diffusive and conductivity properties of electrolytes in the presence of PEG have allowed us to clarify important aspects of the electrostatic properties of aqueous PEG-salt systems and supplies valuable information for salt properties in "mixed solvents". A useful classification of mixed solvents is proposed, distinguishing between "viscous" and "dielectric" mixed solvents.
Selectivity and efficacy towards target cancer cells, as well as biocompatibility, are current ch... more Selectivity and efficacy towards target cancer cells, as well as biocompatibility, are current challenges of advanced chemotherapy powering the discovery of unconventional metal-based drugs and the search for novel therapeutic approaches. Among second-generation metal-based chemotherapeutics, ruthenium complexes have demonstrated promising anticancer activity coupled to minimal toxicity profiles and peculiar biochemical features. In this context, our research group has recently focused on a bioactive Ru(III) complex—named AziRu—incorporated into a suite of ad hoc designed nucleolipid nanosystems to ensure its chemical stability and delivery. Indeed, we proved that the structure and properties of decorated nucleolipids can have a major impact on the anticancer activity of the ruthenium core. Moving in this direction, here we describe a preclinical study performed by a mouse xenograft model of human breast cancer to establish safety and efficacy in vivo of a cationic Ru(III)-based nuc...
Nanoparticles (NPs) are increasingly exploited as diagnostic and therapeutic devices in medicine.... more Nanoparticles (NPs) are increasingly exploited as diagnostic and therapeutic devices in medicine. Among them, superparamagnetic nanoparticles (SPIONs) represent very promising tools for magnetic resonance imaging, local heaters for hyperthermia, and nanoplatforms for multimodal imaging and theranostics. However, the use of NPs, including SPIONs, in medicine presents several issues: first, the encounter with the biological world and proteins in particular. Indeed, nanoparticles can suffer from protein adsorption, which can affect NP functionality and biocompatibility. In this respect, we have investigated the interaction of small SPIONs covered by an amphiphilic double layer of oleic acid/oleylamine and 1octadecanoyl-sn-glycero-3-phosphocholine with two abundant human plasma proteins, human serum albumin (HSA) and human transferrin. By means of spectroscopic and scattering techniques, we analyzed the effect of SPIONs on protein structure and the binding affinities, and only found strong binding in the case of HSA. In no case did SPIONs alter the protein structure significantly. We structurally characterized HSA/SPIONs complexes by means of light and neutron scattering, highlighting the formation of a monolayer of protein molecules on the NP surface. Their interaction with lipid bilayers mimicking biological membranes was investigated by means of neutron reflectivity. We show that HSA/SPIONs do not affect lipid bilayer features and could be further exploited as a nanoplatform for future applications. Overall, our findings point toward a high biocompatibility of phosphocholine-decorated SPIONs and support their use in nanomedicine.
Water-in-oil (W/O) nanoemulsions stabilized by phospholipids (PLs) are increasingly exploited in ... more Water-in-oil (W/O) nanoemulsions stabilized by phospholipids (PLs) are increasingly exploited in a wide spectrum of applications, from pharmaceuticals to food and cosmetic formulations. In this work, we report the design and optimization of an innovative emulsion based on a mixture of phosphoethanolamine (PE) and phosphoglycerol (PG) PLs, inspired by the composition of the inner leaflet of a bacterial outer membrane. Using the natural oil squalene as the continuous organic phase, no additional emulsion stabilizer is needed. On the other hand, a small amount of Span 80 is required when dodecane is used. The obtained nanoemulsions are stable for at least two hours, thus allowing the droplet size and distribution to be characterized by Dynamic Light Scattering (DLS) and the lipid layer structure and dynamics to be analyzed by Electron Paramagnetic Resonance (EPR) spectroscopy. The results indicate that squalene shallowly intercalates among the lipid tail termini, being unable to deeply...
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Papers by Luigi Paduano