Marta Corno

Publications (25) View all

• Article: DFT modeling of 45S5 and 77S soda-lime phospho-silicate glass surfaces: clues on different bioactivity mechanism.

  Enrico Berardo, Alfonso Pedone, Piero Ugliengo, Marta Corno
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  ABSTRACT: The reactivity of bioglasses, which is related to the dissolution of cations and orthosilicate groups in the physiological fluid, strongly depends on the key structural features present at the glass surfaces. Based on the composition and the synthetic routes employed to make the glass, surfaces with very different characteristics and thus presenting different mechanisms of dissolution can be observed. In this paper, the surface structures of two very different bioglass compositions, namely 45S5 (46.1 SiO2, 24.4 Na2O, 26.9 CaO and 2.6 P2O5 mol %) and 77S (80.0 SiO2, 16.0 CaO and 4.0 P2O5 mol %), have been investigated by means of periodic DFT calculations based on PBE functional and localized Gaussian basis set as encoded in the CRYSTAL code. Our calculations show that the two glass surfaces differ by the relative amount of key structural sites such as NBOs, exposed ions, orthosilicate units and small rings. We have demonstrated how the number of these sites affects the surface stability and reactivity (bioactivity).
  Langmuir 04/2013; · 4.19 Impact Factor
• Article: Does Dispersion Dominate over H-Bonds in Drug–Surface Interactions? The Case of Silica-Based Materials As Excipients and Drug-Delivery Agents

  Massimo Delle Piane, Marta Corno, Piero Ugliengo
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  ABSTRACT: doi: 10.1021/ct400073s
  Journal of Chemical Theory and Computation 03/2013; · 5.22 Impact Factor
• Article: Coordination chemistry of Ca sites at the surface of nanosized hydroxyapatite: interaction with H₂O and CO.

  Vera Bolis, Claudia Busco, Gianmario Martra, Luca Bertinetti, Yuriy Sakhno, Piero Ugliengo, Fabio Chiatti, Marta Corno, Norberto Roveri
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  ABSTRACT: The affinity towards water of a selection of well-defined, nanostructured hydroxyapatite (HA) samples was investigated by H(2)O vapour adsorption microcalorimetry and infrared (IR) spectroscopy. A large hydrophilicity of all investigated materials was confirmed. The surface features of hydrated HA were investigated on the as-synthesized samples pre-treated in mild conditions at T=303 K, whereas dehydrated HA features were characterized on samples activated at T=573 K. The relatively large hydrophilicity of the hydrated surface (-Δ(ads)H~100-50 kJ mol(-1)) was due to the interaction of water with the highly polarized H(2)O molecules strongly coordinated to the surface Ca(2+) cations. At the dehydrated surface, exposing coordinatively unsaturated (cus) Ca(2+) cations, H(2)O was still molecularly adsorbed but more strongly (-Δ(ads)H~120-90 kJ mol(-1)). The use of CO adsorption to quantify the Lewis acidic strength of HA surface sites revealed only a moderate strength of cus Ca(2+) cations, as confirmed by both microcalorimetric and IR spectroscopic measurements and ab initio calculations. This result implies that the large HA/H(2)O interaction energy is due to the interplay between cus Ca(2+) sites and nearby hydrophilic PO(4) groups, not revealed by the CO probe. The lower density of cus Ca(2+) cations at the 573 K activated HA surface with respect to the pristine one did not affect the whole hydrophilicity of the surface, as the polarizing effect of Ca sites is so strong to extend up to the fourth hydrated layer, as confirmed by both high-coverage microcalorimetric and IR spectroscopic data. No specific effects due to the investigated specimen preparation method and/or different morphology were observed.
  Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences 03/2012; 370(1963):1313-36. · 2.77 Impact Factor
• Article: Ab initio modelling of protein-biomaterial interactions: influence of amino acid polar side chains on adsorption at hydroxyapatite surfaces.

  Albert Rimola, Marta Corno, Jorge Garza, Piero Ugliengo
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  ABSTRACT: The adsorption from the gas phase of five different amino acids (AAs), namely Gly, Ser, Lys, Gln and Glu, on three surface models of hexagonal hydroxyapatite (HA) has been studied at B3LYP level with Gaussian type basis set within a periodic approach. The AA adsorption was simulated on the (001) and (010) stoichiometric surfaces, the latter both in its pristine and water-reacted form. Low/high AA coverage has been studied by doubling the HA unit cell size. The AAs have been docked to the HA surfaces following the electrostatic complementarity between the electrostatic potentials of AA and the bare HA. Gly adsorbs as a zwitterion at the (001) surface, whereas at the (010) ones, the proton of the COOH group is transferred to the surface resulting in an HA(+)/Gly(-) ion pair. For the other AAs, the common COOH-CH-NH(2) moiety behaves like in Gly, while the specific side-chain functionalities adsorb at the HA surfaces by maximizing electrostatic and H-bond interactions. The interactions between the side chains and the HA surface impart a higher stability compared with the Gly case, with Glu being the strongest adsorbate owing to its high Ca affinity and H-bond donor propensity. For AAs of large size, the adsorption is more favourable in conditions of low coverage as repulsion between adjacent AAs is avoided. For all considered AAs, the strongest interaction is always established on the (010) faces rather than on the (001) one, therefore suggesting an easier growth along the c-direction of HA crystals from AA solutions.
  Philosophical Transactions of The Royal Society A Mathematical Physical and Engineering Sciences 03/2012; 370(1963):1478-98. · 2.77 Impact Factor
• Article: Stability of the Dipolar (001) Surface of Hydroxyapatite

  Fabio Chiatti, Marta Corno, Piero Ugliengo
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  ABSTRACT: The features of the ferroelectric (proton ordered) hydroxyapatite HA (001) surface as derived from the P6 3 hexagonal HA bulk have been studied by periodic density functional calculations using the hybrid B3LYP functional and Gaussian basis set of polarized double-ζ quality. Geometry, surface energy, and electronic features of HA (001) slab models of thickness from 1 nm to almost 50 nm have been computed, by keeping under careful control numerical errors due to the very large system size. The present results reveal that the ferroelectric OH − alignment does not compromise the stability of the HA (001) surface up to the nanometric scale. Indeed, a slab thickness of 43 nm, containing 2640 atoms in the unit cell, exhibits a dipole moment across the slab of 0.73 D, a wide band gap of 7.60 eV, and a surface energy of 1.344 J·m −2 . No sign of "metallization" occurs as for the classical macroscopic polar zinc-or oxygen-terminated ZnO (0001) surfaces, due to counterpolarization of the electronic density of the Ca 2+ and PO 4 3− moieties surrounding the monodimensional OH − polar arrays. These findings may be relevant to explain why, experimentally, HA nanocrystals orient along the main axis of the proto-collagen fibrils with their crystallographic c axis (perpendicular to the {001} crystal plane family).
  The Journal of Physical Chemistry C 02/2012; 116:6108--6114. · 4.80 Impact Factor