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FABRIZIO BERNINI

Assegnista di ricerca
Dipartimento di Scienze della Vita sede ex-Chimica

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Pubblicazioni

2023 - Hydrogen Peroxide Induces Heme Degradation and Protein Aggregation in Human Neuroglobin: Roles of the Disulfide Bridge and the H-bonding in the Distal Heme Cavity [Articolo su rivista]
Di Rocco, G.; Bernini, F.; Battistuzzi, G.; Ranieri, A.; Bortolotti, C. A.; Borsari, M.; Sola, M.
abstract

In this study, human neuroglobin (hNgb) was found to undergo H2O2-induced breakdown of the heme center at a much slower rate than other globins, namely in the timescale of hours against minutes. We studied how the rate of the process is affected by the Cys46/Cys55 disulfide bond and the network of noncovalent interactions in the distal heme side involving Tyr44, Lys67, the His64 heme iron axial ligand and the heme propionate-7. The rate is increased by the Tyr44 to Ala and Phe mutations, however the rate is lowered by Lys67 to Ala swapping. The absence of the disulfide bridge slows down the reaction further. Therefore, the disulfide bond-controlled accessibility of the heme site and the residues at position 44 and 67 affect the activation barrier of the reaction. Wild-type and mutated species form -amyloid aggregates in the presence of H2O2 producing globular structures. Furthermore, the C46A/C55A, Y44A, Y44F and Y44F/C46A/C55A variants yield potentially harmful fibrils. Finally, the nucleation and growth kinetics for the aggregation of the amyloid structures can be successfully described by the Finke-Watzky model.

2022 - PCSK9 Affects Astrocyte Cholesterol Metabolism and Reduces Neuron Cholesterol Supplying In Vitro: Potential Implications in Alzheimer’s Disease [Articolo su rivista]
Papotti, B.; Adorni, M. P.; Marchi, C.; Zimetti, F.; Ronda, N.; Panighel, G.; Lupo, M. G.; Vilella, A.; Giuliani, D.; Ferri, N.; Bernini, F.
abstract

The Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) involvement in Alzheimer's disease (AD) is poorly investigated. We evaluated the in vitro PCSK9 modulation of astrocyte cholesterol metabolism and neuronal cholesterol supplying, which is fundamental for neuronal functions. Moreover, we investigated PCSK9 neurotoxic effects. In human astrocytoma cells, PCSK9 reduced cholesterol content (-20%; p < 0.05), with a greater effect in presence of beta amyloid peptide (A beta) (-37%; p < 0.01). PCSK9 increased cholesterol synthesis and reduced the uptake of apoE-HDL-derived cholesterol (-36%; p < 0.0001), as well as the LDL receptor (LDLR) and the apoE receptor 2 (ApoER2) expression (-66% and -31%, respectively; p < 0.01). PCSK9 did not modulate ABCA1- and ABCG1-cholesterol efflux, ABCA1 levels, or membrane cholesterol. Conversely, ABCA1 expression and activity, as well as membrane cholesterol, were reduced by A beta (p < 0.05). In human neuronal cells, PCSK9 reduced apoE-HDL-derived cholesterol uptake (-41%; p < 0.001) and LDLR/apoER2 expression (p < 0.05). Reduced cholesterol internalization occurred also in PCSK9-overexpressing neurons exposed to an astrocyte-conditioned medium (-39%; p < 0.001). PCSK9 reduced neuronal cholesterol content overall (-29%; p < 0.05) and increased the A beta-induced neurotoxicity (p < 0.0001). Our data revealed an interfering effect of PCSK9, in cooperation with A beta, on brain cholesterol metabolism leading to neuronal cholesterol reduction, a potentially deleterious effect. PCSK9 also exerted a neurotoxic effect, and thus represents a potential pharmacological target in AD.

2021 - Al-Substituted Tobermorites: An Effective Cation Exchanger Synthesized from "end-of-Waste" Materials [Articolo su rivista]
Malferrari, D.; Bernini, F.; Di Giuseppe, D.; Scognamiglio, V.; Gualtieri, A. F.
abstract

The policies to meet the "zero waste"regime and transition to sustainable circular economy can no longer ignore the use of wastes in place of natural resources, and these daunting and vital societal challenges are nowadays being faced by several nations. The main objective of this work was to search waste materials suitable for a quick and environmentally friendly production of a nanoporous geomaterial able to trap toxic metals at the solid/liquid interface. More specifically, the end-of-waste from the thermal inertization of cement-asbestos and glass powder from domestic glass containers have been employed as sources for the hydrothermal synthesis of a tobermorite-rich material (TRM) successfully tested for the selective removal of Pb2+, Zn2+, Cd2+, and Ni2+ from aqueous solutions. The synthesis was carried out in alkaline solution under mild hydrothermal conditions (120 °C) within 24 h. The quantitative phase analyses of the TRM carried out by applying the Rietveld method showed the occurrence of a large amount of well-crystallized 11 Å Al-substituted tobermorites and an amorphous phase and a lower content of aragonite and calcite. Chemical analyses and thermogravimetric measurements coupled with simultaneous evolved gas mass spectrometry highlighted that Al3+ for Si4+ substitutions in the wollastonite-like tetrahedral chains of tobermorites are balanced by the occurrence of Ca2+, Na+, and K+ cations in the interlayer rather than by (OH)- for O2- substitutions in the CaO polyhedra. Time-dependent removal tests clearly indicated that metal cations are selectively adsorbed depending on their concentration in solution. Moreover, the kinetic curves showed that the removal of metals from solution is fast and the equilibrium is almost reached in the first 8 h.

2021 - Molecular structure and ammonia gas adsorption capacity of a Cu(II)-1,10-phenanthroline complex intercalated in montmorillonite by DFT simulations [Articolo su rivista]
Sainz-Diaz, C. I.; Castellini, E.; Escamilla-Roa, E.; Bernini, F.; Malferrari, D.; Brigatti, M. F.; Borsari, M.
abstract

A hydrated complex of 1,10-phenanthroline with Cu2+ cation was intercalated in the interlayer space of montmorillonite. This intercalation occurs initially by through a cation exchange mechanism in which the charge of the complex cation compensates the excess of the negative charge of the interlayer, then, once the cation exchange capacity (CEC) value has been reached, by direct adsorption of the sulfate salt of this complex (i.e. the cation together with its sulfate counterion). This material has showed interesting entrapping properties of gaseous phases and a peculiar chemical reactivity. However, the complete characterization and explanation of the formation of these materials is difficult with only experimental techniques. Hence, we used computational methods at atomic level to know how are the molecular structure of these complexes and their adsorption capacity of ammonia inside the interlayer confined space of montmorillonite for a better understanding of the experimental behaviour. First Principles calculations were performed based on Density Functional Theory (DFT). The intercalation of the phenanthroline-Cu(II) complex inside the nanoconfined interlayer of montmorillonite is energetically favourable in the relative proportion observed experimentally, being a cation exchange process. The further adsorption of the sulfate salt of the phenanthroline-Cu complex is also energetically possible. The adsorption of ammonia molecules in these montmorillonite-phenanthroline-Cu complexes was also favourable according with experimental behaviour.

2021 - Self-Assembled Structures from Solid Cd(II) Acetate in Thiol/Ethanol Solutions: a Novel Type of Organic Chemical Garden [Articolo su rivista]
Bernini, Fabrizio; Castellini, Elena; Sebastianelli, Lorenzo; Bighi, Beatrice; Ignacio Sainz-Díaz, Claro; Mucci, Adele; Malferrari, Daniele; Ranieri, Antonio; Franca Brigatti, Maria; Borsari, Marco
abstract

Cd(II) acetate in tablet form, immersed in ethanol solutions with a high concentration of heptanethiol (30-80 mM) was able to develop self-assembled sail-shaped structures. The solution in which the self-assembled structure is formed is totally organic (both solute and solvent), thus representing a unique case among organic Chemical Gardens. The constituting material for this new Chemical Garden (CG) is made of a single phase, namely a cadmium heptanethiolate with a microcrystalline structure consisting of a central cluster [CdnSn]. The morphological and structural features were studied using different techniques (SEM-EDS, elemental analysis, FT-IR, 113Cd MAS NMR, XRPD). A crystalline cell for the Cd(II) heptanethiolate cluster was obtained that completely differs from that of the solid phase precipitated by mixing an ethanol solution of Cd(II) acetate with heptanethiol. It follows that the conditions under which the formation of Cd(II) thiolate occurs (slowly from solid, quickly from solution) play a critical role in determining the nature and structure of the precipitating phase.

2021 - The Copper Chemical Garden as a Low Cost and Efficient Material for Breaking Down Air Pollution by Gaseous Ammonia [Articolo su rivista]
Castellini, Elena; Bernini, Fabrizio; Sebastianelli, Lorenzo; Bighi, Beatrice; Ignacio Sainz-Diaz, Claro; Mucci, Adele; Malferrari, Daniele; Ranieri, Antonio; Gorni, Giulio; Marini, Carlo; Brigatti, Maria Franca; Borsari, Marco
abstract

Chemical garden (CG) from copper(II) sulfate, nitrate and chloride (CG CuSO4, CG Cu(NO3)2, CG CuCl2) were grown and characterized from the structural and compositional point of view using scanning electron microscopy, X-ray powder diffraction, elemental analysis, thermogravimetric analyses coupled with mass spectrometry, and DR (Diffuse Reflectance) UV-Vis-Nir spectroscopy. The main crystalline phases, controlled by the anion of the starting salt, were brochantite and kobyashevite for CG CuSO4, gerhardtite, rouaite and anthonyite for CG Cu(NO3)2, and atacamite for CG CuCl2. The materials were then exposed to ammonia vapors to test the effectiveness of their entrapping property. All materials proved to be very efficient and rapid in the uptake of ammonia which invariably results in the formation of a Cu(II)/NH3 complex. However, after a few tens of minutes, CG Cu(NO3)2 and CG CuCl2 release water and get wet, thereby resulting unsuitable for applications. Only CG CuSO4 keeps dry for at least 25 hours. This makes it a valid candidate for building devices for trapping ammonia and possibly other gases capable of interacting with Cu (II). The entrapment of ammonia by this material was also characterized by 1H and 29Si MAS-NMR XAS spectroscopies.

2020 - A new material based on montmorillonite and Cu(II)-phenanthroline complex for effective capture of ammonia from gas phase [Articolo su rivista]
Castellini, E.; Malferrari, D.; Bernini, F.; Bighi, B.; Mucci, A.; Sainz-Diaz, I. C.; Serrano, A.; Castro, G. R.; Brigatti, M. F.; Borsari, M.
abstract

The intercalation of [Cu(Phen)(H2O)2]2+ (CuPhen) in montmorillonite (Mt) produces a stable hybrid material that is very efficient in removing NH3 from gas phase even at extremely low pressures. The process was studied by elemental analysis, X-ray powder diffraction, thermal analysis coupled with evolved gas mass spectrometry and DR UV–Vis, NMR and X-ray absorption spectroscopy. The adsorption of CuPhen on Mt consists of two consecutive steps. During the first one, CuPhen intercalates alone into Mt through a cation exchange process, afterwards CuPhen and SO42− ions entry jointly into the mineral interlayer. The two-steps adsorption process is described by a VI-type isotherm, successfully fitted by two independent Frumkin isotherms. NH3 trapping is long-lasting, easy, fast even at extremely low gas pressure and reversible under mild conditions. Mt containing CuPhen always results well performant in removing ammonia from gas phase, but an appreciably higher adsorption capacity of NH3 is obtained when SO42− ion is absent from the interlayer. This hybrid montmorillonite is thus a promising material to be used in industrial or environmental contexts, as an efficient air-cleaner.

2020 - Electrochemical data on redox properties of human Cofilin-2 and its Mutant S3D [Articolo su rivista]
Pignataro, M.; Di Rocco, G.; Lancellotti, L.; Bernini, F.; Subramanian, K.; Castellini, E.; Bortolotti, C. A.; Malferrari, D.; Moro, D.; Valdrè, G.; Borsari, M.; del Monte, F.
abstract

The reported data are related to a research paper entitled "Phosphorylated cofilin-2 is more prone to oxidative modifications on Cys39 and favors amyloid fibril formation" [1]. Info about the formation and redox properties of the disulfide bridge of a protein is quite difficult to obtain and only in a few cases was it possible to observe a cyclic voltammetry (CV) signal [2,3]. Human cofilin-2 contains two cysteines (Cys39 and Cys80) which can be oxidized in suitable conditions and form a disulfide bridge [1]. For this purpose, CV measurements were carried out on human cofilin-2 WT and its mutant S3D immobilized on a gold electrode coated by an anionic self-assembled monolayer (SAM), after a pre-oxidation time which was fundamental for observing a CV signal relating to the oxidation/reduction process of the disulfide bridge of the proteins. The data include CV curves obtained with and without electrochemical pre-oxidation and after oxidation with H2O2. In addition, the plot of the cathodic peak current vs. electrochemical pre-oxidation time and the pH dependence of the formal potential (E°’) are reported. The data obtained by CV measurements were used to determine the time required to form the disulfide bridge for the immobilized proteins and, consequently, to observe the CV signal, to calculate the E°’ values and analyse the pH dependence of E°’. The electrochemical data were provided which will be useful for further electrochemical investigations regarding proteins bearing disulfide bridge(s) or cysteines prone to oxidation.

2020 - Hermetia illucens (L.) larvae as chicken manure management tool for circular economy [Articolo su rivista]
Bortolini, Sara; Macavei, Laura Ioana; Saadoun, Jasmine Hadj; Foca, Giorgia; Ulrici, Alessandro; Bernini, Fabrizio; Malferrari, Daniele; Setti, Leonardo; Ronga, Domenico; Maistrello, Lara
abstract

The increased request for poultry meat and eggs of a rising human population requires more efficient and cleaner methods to manage increasing quantities of chicken manure. The black soldier fly Hermetia illucens is known as an efficient bio-converter of organic waste in proteins and fats, with the advantage that the larval frass is supposed to have compost-like properties. In the view to identify the operating conditions for the sustainable management and valorization of livestock waste at a pre-industrial scale, this study is aimed at: i) optimizing the growth of H. illucens on a mixture of chicken manure, chabazite and water; ii) assessing the soil amendment properties of the larval frass obtained from the optimized mixture. Preliminary trials allowed defining the basic rearing conditions in terms of temperature and substrate components. A mixture design based on a special cubic model allowed identifying the best mixture for H. illucens larvae growth, which consists in 34.5% chicken manure, 58.3% water and 7.2% coarse chabazite. This mix led to about 86% of alive prepupae weighting 90 mg on average, and to a reduction of the initial substrate amount by more than 75%. The larval frass obtained from this mixture showed soil improver properties, suggesting its use to supply the common peat based growing media for potted baby-leaf lettuce production. Overall, H. illucens larvae have proved to be a useful tool to favor a more sustainable management of chicken manure by strongly reducing its amount and closing its recovery cycle obtaining high value products for agricultural purposes.

2020 - Interlayer-confined Cu(II) complex as an efficient and long-lasting catalyst for oxidation of H2s on montmorillonite [Articolo su rivista]
Castellini, E.; Bernini, F.; Sebastianelli, L.; Sainz-Diaz, C. I.; Serrano, A.; Castro, G. R.; Malferrari, D.; Brigatti, M. F.; Borsari, M.
abstract

Removal of highly toxic H2S for pollution control and operational safety is a pressing need. For this purpose, a montmorillonite intercalated with Cu(II)-phenanthroline complex [Cu[(Phen)(H2O)2]2+ (Mt-CuPhen) was prepared to capture gaseous H2S under mild conditions. This hybrid material was simple to obtain and demonstrated an outstanding ability to entrap H2S at room temperature, retaining high efficiency for a very long time (up to 36.8 g of S/100 g Mt-CuPhen after 3 months of exposure). Sorbent and H2S uptake were investigated by elemental analysis, X-ray powder diffraction measurements, diffuse reflectance (DR) UV–Vis and infrared spectroscopy, thermal analysis and evolved gas mass spectrometry, scanning electron microscopy equipped with energy-dispersive X-ray spectrometer, and X-ray absorption spectroscopy. The H2S capture was studied over time and a mechanism of action was proposed. The entrapping involves a catalytic mechanism in which [Cu[(Phen)(H2O)2]2+ acts as catalyst for H2S oxidation to S0 by atmospheric oxygen. The low cost and the long-lasting performance for H2S removal render Mt-CuPhen an extremely appealing trap for H2S removal and a promising material for many technological applications.

2020 - Phosphorylated cofilin-2 is more prone to oxidative modifications on Cys39 and favors amyloid fibril formation [Articolo su rivista]
Pignataro, M.; Di Rocco, G.; Lancellotti, L.; Bernini, F.; Subramanian, K.; Castellini, E.; Bortolotti, C. A.; Malferrari, D.; Moro, D.; Valdre, G.; Borsari, M.; Monte, F. D.
abstract

Cofilins are small protein of the actin depolymerizing family. Actin polymerization/depolymerization is central to a number of critical cellular physiological tasks making cofilin a key protein for several physiological functions of the cell. Cofilin activity is mainly regulated by phosphorylation on serine residue 3 making this post-translational modification key to the regulation of myofilament integrity. In fact, in this form, the protein segregates in myocardial aggregates in human idiopathic dilated cardiomyopathy. Since myofilament network is an early target of oxidative stress we investigated the molecular changes induced by oxidation on cofilin isoforms and their interplay with the protein phosphorylation state to get insight on whether/how those changes may predispose to early protein aggregation. Using different and complementary approaches we characterized the aggregation properties of cofilin-2 and its phosphomimetic variant (S3D) in response to oxidative stress in silico, in vitro and on isolated cardiomyocytes. We found that the phosphorylated (inactive) form of cofilin-2 is mechanistically linked to the formation of an extended network of fibrillar structures induced by oxidative stress via the formation of a disulfide bond between Cys39 and Cys80. Such phosphorylation-dependent effect is likely controlled by changes in the hydrogen bonding network involving Cys39. We found that the sulfide ion inhibits the formation of such structures. This might represent the mechanism for the protective effect of the therapeutic agent Na2S on ischemic injury.

2020 - Tuning of halobenzenes uptake in montmorillonite from gas phase through a functionalization process involving Cu(II)-phenanthroline and heptanethiol [Articolo su rivista]
Castellini, Elena; Malferrari, Daniele; Bernini, Fabrizio; Bighi, Beatrice; Mucci, Adele; Sainz Diaz, Ignacio Claro; Serrano, Aida; Castro, German R.; Brigatti, Maria Franca; Borsari, Marco
abstract

In this paper, montmorillonite functionalized with a Cu(II)-phenanthroline complex (Mt-CuPhen) and then exposed to heptanethiol vapors (Mt-CuPhen-HPT) was tested for the capture of halobenzenes in gas phase. The treatment of Mt-CuPhen with heptanethiol vapors produced important compositional changes involving Cu(II) reduction, oxidation of thiol to disulfide and dehydration of the mineral interlayer space. Entrapping experiments were carried out on fluorobenzene, chlorobenzene and bromobenzene at 25 and 45°C. The hybrid material proved to be very efficient for all halobenzenes and especially for fluorobenzene. Observed performances are slightly affected by temperature. Halobenzene desorption occurred even at 100°C, a temperature quite lower than that required for decomposition of Mt-CuPhen-HPT. The Mt-CuPhen-HPT hybrid material, therefore, can be reused several times and requires low energy costs for regeneration. An alternative regeneration procedure based on disulfide removal has been proposed as well. Mt-CuPhen-HPT was extensively characterized before and after halobenzenes immobilization through elemental analysis, UV-Vis measurements, thermogravimetric analyses, FTIR, NMR and X-ray absorption spectroscopies.

2019 - Structural properties of adsorbent phyllosilicates rule the entrapping ability of intercalated iron-phenanthroline complex towards thiols [Articolo su rivista]
Castellini, E.; Malferrari, D.; Bernini, F.; Mucci, A.; Borsari, M.; Brigatti, M. F.
abstract

The interaction of volatile organic sulfur derivatives, such as 1-heptanethiol (C7H16S), with clay minerals treated with a μ-oxo Fe3+-phenanthroline 1:1 complex results strongly affected by crystal chemical properties of pristine mineral phases. In particular, two sepiolite clays with different structural features demonstrated significantly different ability to immobilize the Fe3+-phenanthroline complex at two pH values (pH = 5.4 and pH = 2.3). The most effective binding was obtained with sepiolite with higher structural disorder at pH 5.4. Accordingly, the resulting hybrid material showed also the greatest efficiency in removal of thiol in gas phase. A direct correlation can be established between the adsorption of the Fe3+-phenanthroline complex and the gas binding process at room temperature. In fact, 1-heptanethiol entrapping occurs via redox reactions between Fe3+ and a first thiol molecule to give the reduced Fe2+-phenanthroline complex and disulfide, followed by the binding of further thiols to the reduced metal centre. The extremely high amount of thiol immobilized by the hybrid material also suggests the co-presence of a catalytic mechanism that guarantees the reoxidation of Fe+2 to Fe+3 and the restoration of redox reactions with thiol. Investigation and conclusions were supported by the several experimental techniques: elemental analysis, X-ray powder diffraction analyses, UV–Vis measurements, FT-IR and NMR spectroscopies, thermogravimetric analyses.

2019 - Sulfur bearing and aromatic compound trapping by layered silicates: a great start for innovative technological applications [Abstract in Atti di Convegno]
Malferrari, D.; Bernini, F.; Bighi, B.; Borsari, M.; Brigatti, M. F.; Castellini, E.; Mucci, A.; Sebastianelli, L.
abstract

2019 - Trapping at the Solid-Gas Interface: Selective Adsorption of Naphthalene by Montmorillonite Intercalated with a Fe(III)-Phenanthroline Complex [Articolo su rivista]
Castellini, E.; Malferrari, D.; Bernini, F.; Sainz Diaz, C. I.; Mucci, A.; Sola, M.; Brigatti, M. F.; Borsari, M.
abstract

In this study, stable hybrid materials (Mt-Fe(III)Phen), made by the μ-oxo Fe(III)-phenanthroline complex [(OH 2 ) 3 (Phen)FeOFe(Phen)(OH 2 ) 3 ] 4+ (Fe(III)Phen) intercalated in different amounts into montmorillonite (Mt), were used as a trap for immobilizing gaseous benzene and naphthalene and their mono chloro-derivatives at 25 and 50 °C. The entrapping process was studied through elemental analysis, magic angle spinning NMR spectroscopy, thermal analysis, and evolved gas mass spectrometry. Naphthalene and 1-chloronaphthalene were found to be immobilized in large amount at both temperatures. Molecular modeling allowed designing of the structure of the interlayer in the presence of the immobilized aromatic molecules. Adsorption is affected by the amount of the Fe complex hosted in the interlayer of the entrapping hybrid materials. On the contrary, under the same conditions, benzene and chlorobenzene were not adsorbed. Thermal desorption of naphthalenes was obtained under mild conditions, and immobilization was found to be reversible at least for 20 adsorption/desorption cycles.

2018 - Chemical trapping of gaseous H⁠2S at high and low partial pressures by an iron complex immobilized inside the montmorillonite interlayer [Articolo su rivista]
Malferrari, Daniele; Castellini, Elena; Bernini, Fabrizio; Serrano Rubio⁠, Aida; Rafael Castro, German; Ignacio Sainz-Díaz⁠, Claro; Caleffi, Matteo; Brigatti, Maria Franca; Borsari, Marco
abstract

A stable hybrid material (Mt-Fe(III)Phen) formed by intercalation of the μ-oxo Fe(III)-phenanthroline complex [(OH⁠2)⁠3(Phen)FeOFe(Phen)(OH⁠2)⁠3]⁠4+ (Fe(III)Phen) in montmorillonite (Mt) is able to immobilize H⁠2S in gaseous phase with high efficiency even at extremely low pressures. DR UV–vis and I.R. spectroscopies, elemental analysis, X-ray powder diffraction, thermal analysis coupled with evolved gas mass spectrometry, and X-ray absorption spectroscopy show that the material has high adsorption capacity, performs fast H⁠2S trapping and is long-lasting. Moreover, even extremely low levels of H⁠2S can be removed easily and quickly from gaseous phase using a suitable amount of the trapping material. The immobilization mechanism likely involves a redox reaction between iron (III) and one S⁠2− ion, followed by the binding of a second S⁠2− ion to the metal centre. The process takes place at room temperature, is reversible for several cycles, and does not require pre-treatment of neither gaseous H⁠2S nor the adsorbent material. Therefore, this modified montmorillonite is a promising material to get rid of H⁠2S in processes of environmental interest and to obtain gaseous (and gasifiable) high quality hydrocarbons in fuels refineries.

2018 - Experimental and Theoretical Investigation of Intercalation and Molecular Structure of Organo-Iron Complexes in Montmorillonite [Articolo su rivista]
Sainz-Díaz, C. I.; Bernini, F.; Castellini, E.; Malferrari, D.; Borsari, M.; Mucci, A.; Brigatti, M. F.
abstract

The intercalation of the μ-oxo Fe(III)-phenanthroline 1:1 complex [(OH2)3(Phen)FeOFe(Phen)(OH2)3]+4 inside montmorillonite yielded a nanostructured material with strong and selective entrapping ability toward thiol molecules and hydrogen sulfide. In this work, experiments and computational molecular modeling by means of quantum mechanical calculations has been applied to study the molecular structure and interactions between this complex and the interlayer of montmorillonite. This approach allowed the identification of the geometrical disposition of the complexes inside the interlayer, the characterization of the hydration and coordination water molecules, and the explanation of the physico-chemical properties of these functionalized materials. The antiferromagnetic spin configuration of the Fe(III) ions results in the most stable state. Two conformers of the complex have been considered, having the phenanthroline rings in twisted or in parallel planes, respectively, and the transition of one conformer into the other has been explored by molecular dynamics simulations. The conformer with phenanthroline rings in parallel planes is found to be the favored species for intercalation in montmorillonite. Both experimental nuclear magnetic resonance analysis and adsorption isotherms are consistent with the modeling results. Different complex amount, equal and double of the cation exchange capacity (CEC) of montmorillonite, and hydration states inside the interlayer have been investigated reproducing faithfully the experimental d(001) spacing of the montmorillonite in the different conditions. The complex molecules intercalated over the CEC of montmorillonite adopt a disposition of the phenanthroline rings perpendicular to that of the complex already introduced by cation exchange.

2018 - Valorisation of chicken manure using insects: Hermetia illucens in the VALORIBIO Project [Abstract in Atti di Convegno]
Bortolini, S.; Macavei, L. I.; Foca, G.; Ulrici, A.; Bernini, F.; Malferrari, D.; Maistrello, L.
abstract

Over the last decades, the need to manage organic waste in a more efficient way and the need to find new sources of energy have opened new horizons in the use of insects for various purposes (e.g. food, feed, biodiesel). The ValoriBio project focuses on the valorisation of chicken manure through the use of Hermetia illucens (Diptera, Stratiomyidae), for the production of high quality compost and bioplastics for agricultural purposes. This study is aimed at the optimisation of the growth parameters of H. illucens on a substrate formed by a mixture of chicken manure, zeolitic tuff (Ca-chabazite), soil improver obtained from pruning shears of urban green, and water. The addition of the Ca-chabazite aims to reduce unpleasant smells, trap the excess of ammonium, and contribute to the formation of a post-breeding substrate which can be used as high-quality compost. The parameters to be maximized were: percentage and maximum average weight of prepupae and percentage of emerged adult flies. Results of a first trial, based on a special cubic model of combined mixture design that tested different ranges of the substrates at 27 and 33°C, recommended the removal of the soil improver and the selection of 27°C as preferred rearing temperature. A second trial considered different ranges of chicken manure, Ca-chabazite (at two different particle sizes) and water. Results from this experiment allowed the definition of the optimal composition for the substrates to obtain the highest percentage of prepupae (71-74%) and the highest average prepupae weight (0.069-0.072g), and were therefore used to plan the validation test, where chicken manure ranged between 34.5 and 45.0%, Ca-chabazite (larger particle size) between 5.0 and 7.2%, and water between 50.0 and 58.3%. These results are the basis to develop an optimized rearing cycle of H. illucens in an automatized pilot plant for organic waste conversion.

2017 - Baseline studies of The Clay Minerals Society Source Clay montmorillonite STx-1b [Articolo su rivista]
Castellini, Elena; Malferrari, Daniele; Bernini, Fabrizio; Brigatti, Maria Franca; Castro, German Rafael; Medici, Luca; Mucci, Adele; Borsari, Marco
abstract

For more than forty years, The Clay Minerals Society has dispensed a set of source clays which have enabled a large number of researchers to work on identical materials. Many of these source clays remained unchanged over the years but, conversely, other clays have gone out of stock and thus were replaced. This was the fate of montmorillonite STx-1a, which was replaced by STx-1b. Although STx-1a and STx-1b share many basic chemical and mineralogical features, some minor differences exist that can affect behavior. A baseline characterization of the source clay STx-1b, which was the objective of this study, was, therefore, necessary to provide researchers a tool useful not only for new investigation but also to compare new results obtained on STx-1b with literature data on STx-1a. This characterization was gained using traditional and advanced methods that include: 1) chemical composition (major and trace elements); 2) cation exchange capacity determination; 3) thermal analyses coupled with evolved gas mass spectrometry; 4) quantitative mineralogical characterization using powder X-ray diffraction and Rietveld-RIR (Reference Intensity Ratio) refinement; 5) X-ray absorption spectroscopy at the Fe K-edge; 6) diffuse reflectance ultraviolet-visible and infrared spectroscopies; 7) 29Si, 27Al, and 1H magic-angle spinning nuclear magnetic resonance measurements. According to this multi-analytical approach, the montmorillonite chemical formula is [4](Si7.753 Al0.247) [6](Al3.281 Mg0.558 Fe0.136 Ti0.024 Mn0.002) [12](Ca0.341 Na0.039 K0.061) O20 (OH)4.

2017 - Crystal chemical characterization and computational modeling of a μ-oxo Fe(III) complex with 1,10-phenanthroline clarify its interaction and reactivity with montmorillonite [Articolo su rivista]
Brigatti, Maria Franca; Díaz, Claro Ignacio Sainz; Borsari, Marco; Bernini, Fabrizio; Castellini, Elena; Malferrari, Daniele
abstract

This work provides a systematic study of the μ-oxo-di-fac-[triaqua-(1,10-phenanthroline-κ2N,N′)-iron(III)]bis(sulfate), [(OH2)3(phen)FeOFe(phen)(OH2)3] (SO4)2 (phen = phenanthroline). Crystal structure is determined by single-crystal X-ray diffraction data and refined to R = 0.039. The crystal structure is monoclinic (Z = 2), space group P21 with unit cell dimensions a = 8.5157(3), b = 17.6434(5), c = 9.9678(3) Å, β = 90.133(2)°, V = 1497.62(8) Å3. The triaqua(1,10-phenanthroline)iron(III) parts are linked through one oxo-bridge. Both Fe(III) cations show a distorted octahedral coordination. The single-crystal data are complemented by computational chemistry modeling at quantum mechanical level, X-ray powder diffraction at room and high temperature conditions and by thermal analysis. Molecular modeling suggests that the role of the crystallization water molecules is critical to establish the intermolecular interactions for the stability of the crystal structure.

2017 - Effective and Selective Trapping of Volatile Organic Sulfur Derivatives by Montmorillonite Intercalated with a μ-oxo Fe(III)-Phenanthroline Complex [Articolo su rivista]
Bernini, Fabrizio; Castellini, Elena; Malferrari, Daniele; Castro, German Rafael; Sainz Díaz, Claro Ignacio; Brigatti, Maria Franca; Borsari, Marco
abstract

The mu-oxo Fe(III) phenatithroline Complex [(OH2)(3)(Phen)FeOFe(Phen) (OH2)(3)](+4) intercalated in montmorillonite provides a stable hybrid material. In this study, the ability and efficiency of this material to immobilize thiols in gas phase, acting as a trap at the solid-gas interface, were investigated. Aliphatic thiols containing both hydrophilic and hydrophobic end groups were chosen to test the selectivity of this gas trap. DR-UV vis, IR, elemental analysis, thermal analysis and evolved gas mass spectrometry, X-ray powder diffraction, and X-ray absorption spectroscopy techniques were employed to characterize the hybrid material before and after thiol exposure and to provide information on the entrapping process. Thiol immobilization is very large, up to 21% w/w for heptanethiol. In addition, evidence was obtained that immobilization occurs through the formation of a covalent bond between the iron of the complex and the sulfur of the thiol. This provides an immobilization process characterized by a higher stability with respect to the method's based on physi-adsorption. Thiol immobilization resulted thermally reversible at least for 20 adsorption/desorption cycles. Unlike standard desulfurization processes like hydrotreating and catalytic oxidation which work at high temperatures and pressures, the present system is able to efficiently trap thiols at room temperature and pressure, thus saving energy. Furthermore,we found that the selectivity of thiol immobilization can be tuned acting on the amount of complex intercalated in montmorillonite. In particular, montmorillonite semisaturated with the complex captures both hydrophobic and hydrophilic thiols, while the saturated montmorillonite shows a strong selectivity toward the hydrophobic molecules.

2017 - Experimental and Molecular Dynamics Investigation Proves That Montmorillonite Traps the Biogenic Amines Histamine and Tyramine [Articolo su rivista]
Malferrari, Daniele; Bernini, Fabrizio; Tavanti, Francesco; Tuccio, Luca; Pedone, Alfonso
abstract

Biogenic amines present in high concentrations in foods obtained through fermentation could have toxic effects and contribute to the arising of allergies. For this reason, their removal is of great importance. In this work, we used an experimental and computational approach to investigate the interaction between a calcium montmorillonite, a layered silicate very common in clays, and the two biogenic amines histamine and tyramine, obtaining deep insight into their binding modalities and structural organization. Calcium montmorillonite can exchange almost all its interlayer Ca2+with the protonated histamine and tyramine, thus reducing their concentration in water solution. The adopted multianalytical approach allowed classification of the interaction mechanism as an intercalation. Molecular dynamics simulations showed that the intercalated histamine and tyramine preferentially interact, through the protonated amino nitrogen, with tetrahedral aluminum bearing a net negative charge, whereas interactions with neutral tetrahedral silica is less favorable. We observed that most of histamine molecules bind in the center and above the 6T net of the silica sheet, but for electrostatic constraints they cannot occupy the center of two adjacent 6T nets as occurs for tyramine.

2016 - Excitation-Energy Transfer Paths from Tryptophans to Coordinated Copper Ions in Engineered Azurins: a Source of Observables for Monitoring Protein Structural Changes [Articolo su rivista]
DI ROCCO, Giulia; Bernini, Fabrizio; Borsari, Marco; Martinelli, Ilaria; Bortolotti, Carlo Augusto; Battistuzzi, Gianantonio; Ranieri, Antonio; Caselli, Monica; Sola, Marco; Ponterini, Glauco
abstract

The intrinsic fluorescence of recombinant proteins offers a powerful tool to detect and characterize structural changes induced by chemical or biological stimuli. We show that metal-ion binding to a hexahistidine tail can significantly broaden the range of such structurally sensitive fluorescence observables. Bipositive metal-ions as Cu2+, Ni2+ and Zn2+ bind 6xHis-tag azurin and its 6xHis-tagged R129W and W48A-R129W mutants with good efficiency and, thereby, quench their intrinsic fluorescence. Due to a much more favourable spectral overlap, the 6xHis-tag/Cu2+ complex(es) are the most efficient quenchers of both W48 and W129 emissions. Based on simple Förster-type dependence of energy-transfer efficiency on donor/acceptor distance, we can trace several excitation-energy transfer paths across the protein structure. Unexpected lifetime components in the azurin 6xHis-tag/Cu2+ complex emission decays reveal underneath complexity in the conformational landscape of these systems. The new tryptophan emission quenching paths provide additional signals for detecting and identifying protein structural changes.

2016 - Pre-amyloid oligomers budding:a metastatic mechanism of proteotoxicity [Articolo su rivista]
Bernini, Fabrizio; Malferrari, Daniele; Pignataro, Marcello; Bortolotti, Carlo Augusto; DI ROCCO, Giulia; Lancellotti, Lidia; Brigatti, Maria Franca; Kayed, Rakez; Borsari, Marco; Del Monte, Federica; Castellini, Elena
abstract

The pathological hallmark of misfolded protein diseases and aging is the accumulation of proteotoxic aggregates. However, the mechanisms of proteotoxicity and the dynamic changes in fiber formation and dissemination remain unclear, preventing a cure. Here we adopted a reductionist approach and used atomic force microscopy to define the temporal and spatial changes of amyloid aggregates, their modes of dissemination and the biochemical changes that may influence their growth. We show that pre-amyloid oligomers (PAO) mature to form linear and circular protofibrils, and amyloid fibers, and those can break reforming PAO that can migrate invading neighbor structures. Simulating the effect of immunotherapy modifies the dynamics of PAO formation. Anti-fibers as well as anti-PAO antibodies fragment the amyloid fibers, however the fragmentation using anti-fibers antibodies favored the migration of PAO. In conclusion, we provide evidence for the mechanisms of misfolded protein maturation and propagation and the effects of interventions on the resolution and dissemination of amyloid pathology.

2015 - Solvent tunes the peroxidase activity of cytochrome c immobilized on kaolinite [Articolo su rivista]
Castellini, Elena; Bernini, Fabrizio; Berto, Marcello; Borsari, Marco; Sola, Marco; Ranieri, Antonio
abstract

The adsorption process and the peroxidase activity of yeast cytochrome c (ycc) immobilized on kaolinite (Kaol) were investigated in mixed ethanol/water solutions. The protein strongly adsorbs on the surface of the clay mineral and the thermodynamic adsorption constant increases with increasing ethanol concentration. The adsorption parameters suggest that in ycc a conformational transition from molten globule to helical state occurs in solution for ethanol concentration above 20%. The peroxidase activity of ycc immobilized on Kaol increases from 0% to 20% ethanol (v/v), then it progressively decreases and almost vanishes in pure ethanol. The catalytic properties of adsorbed yccwere studied in 20 and 40% ethanol solutionswhich correspond to the molten globule and to the helical state, respectively. In both cases, catalysis adheres to theMichaelis–Menten model. Themolten globule state, which binds more weakly to kaolinite than the helical state, was found to be more catalytically active. This study is meant to identify the physicochemical factors that modulate the catalytic activity of this kaolinite-based interface of broad applicability.

2015 - Stepwise structuring of the adsorbed layer modulates the physico-chemical properties of hybrid materials from phyllosilicates interacting with the μ-oxo Fe+3-phenanthroline complex [Articolo su rivista]
Bernini, Fabrizio; Castellini, Elena; Malferrari, Daniele; Borsari, Marco; Brigatti, Maria Franca
abstract

The -oxo Fe+3-phenanthroline 1:1 complex [(OH2)3(Phen)FeOFe(Phen)(OH2)3]+4 (hereafter Fe+3Phen) was successfully immobilized on montmorillonite (Mt) and kaolinite (Kt) minerals. Adsorption data on both minerals described an adsorption isotherm of VI type and were successfully fitted using two independent Frumkin isotherms. The interaction between the complex and the minerals is strong and yields two stable hybrid materials: Kt-Fe+3Phen and Mt-Fe+3Phen. DR UV-Vis, elemental analysis, TGA-MSEGA, temperature-controlled XRPD techniques were used to characterize the structural properties of the hybrid materials. These investigations showed that the Fe+3Phen adsorption occurs stepwise via the formation of a bilayer structure. The first layer is the result of a cation exchange process involving the negative charges of the mineral while the second one probably forms through stacking interaction and/or sulphate ions bridging. XRD diffraction measurements show that in Mt the second layer formation is accompanied by a super- structuring of the interlayer that changes the thermal and chemical properties of the composite material. In particular, interesting catalytic properties are observed in Mt-Fe+3Phen samples, but they are completely suppressed with the formation of the Fe+3Phen bilayer structure.

2013 - Enhancing Biocatalysis: The Case of Cytochrome c Unfolded Immobilized on Kaolinite [Articolo su rivista]
Castellini, Elena; Bortolotti, Carlo Augusto; DI ROCCO, Giulia; Bernini, Fabrizio; Ranieri, Antonio
abstract

Urea-unfolded wild-type cytochrome c and its variants immobilized on kaolinite show peroxidase activity that is significantly higher than that of the folded wild-type protein. The accessibility of the substrate to the metal center and the influence of strategic amino acidic residues on the surface of the protein are discussed. This approach sheds light on the factors affecting the catalytic activity of a new versatile biocatalytic interface.

2013 - Sodium hexametaphosphate interaction with 2:1 clay minerals illite and montmorillonite [Articolo su rivista]
Castellini, Elena; Berthold, C.; Malferrari, Daniele; Bernini, Fabrizio
abstract

The interaction of an efficient deflocculant, sodium hexametaphosphate (NaHMP), with illite and montmorillonite samples of different origins was investigated analyzing the HMP uptake (adsorption on mineral surface and/or intercalation inside the mineral interlayer) and the ion release mechanisms. HMP adsorption isotherms on a standard Na-saturated illite were determined at different temperatures providing the thermodynamic parameters of the process and the maximum adsorbed amount of the ion on this mineral. The data indicate that the adsorption process is hindered compared to that on kaolinite and are consistent with the hypothesis that HMP is chemiadsorbed on the aluminol edge sites, forming Al-O-P linkages. The effect of HMP on the natural illite and montmorillonite samples was analyzed using different techniques. Inductively coupled plasma optical emission spectroscopy (ICP-OES) measurements were used to detect the concentration of P, Si, Al, Ca, Mg and K in deflocculant solutions wetting the clay minerals in order to detail the immobilization, dissolution and exchange reactions associated to the deflocculant activity. Thermal analysis and XRD measurements were used as well to gain information on the properties of the HMP-treated clay mineral samples. Montmorillonite samples show a peculiar ability to immobilize HMP. Intercalation processes involving the formation of Ca2+/HMP complexes inside the mineral interlayer are proposed to explain this result and could be the reason of the well known decrease in the deflocculant efficiency of HMP in ceramic slurries rich in montmorillonite.

2012 - The Met80Ala point mutation enhances the peroxidase activity of immobilized cytochrome c [Articolo su rivista]
Ranieri, Antonio; Bernini, Fabrizio; Bortolotti, Carlo Augusto; Castellini, Elena
abstract

The effects of replacement of the axial methionine 80 hemeligand with a non-coordinating alanine on the peroxidaseactivity of kaolinite-immobilized cytochrome c wereinvestigated at different pH values. The catalytic activity10 of the adsorbed mutant was found remarkably higher thanthat of wild-type cytochrome c. The pH dependence ofVmax and KM values is discussed in term of accessibility ofthe substrates to the metal center and surface charge ofkaolinite. Our approach, based on the combined use of15 adsorption on kaolinite and protein engineering, endowsthis bioinorganic interface with remarkable catalyticproperties.

2011 - pH-dependent peroxidase activity of yeast cytochrome c and its triple mutant adsorbed on kaolinite [Articolo su rivista]
Ranieri, Antonio; Bernini, F.; Bortolotti, Carlo Augusto; Bonifacio, A.; Sergo, V.; Castellini, Elena
abstract

The peroxidase activity of wild type yeast cytochrome c and its triple mutant K72AK73AK79A adsorbed onto kaolinite was investigated as a function of pH and temperature. Both adsorbedproteins displayed an appreciable catalytic activity, which remained constant from pH 7 to 10, decreased below pH 7 and showed a remarkable increase at pH values lower than 4. In the whole pH range investigated the catalytic activity of the adsorbed wild type cytochrome c was higher than that of the mutant. Both diffuse-reflectance UV-Vis and Resonance Raman spectroscopies applied on solid samples were used to probe the structural features responsible for the catalytic activity of the immobilized proteins. At neutral and alkaline pH values a six-coordinate low-spin form of cytochrome c was observed, while at pH < 7 the formation of a high-spin species occurred whose population increased at decreasing pH. The orientation and exposure of the haem to the substrate - strictly dependent on adsorption - was found to affect the peroxidase activity.