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A study of the hydrogen bonds effect on the water density and the liquid-liquid transition

Science China(Physics,Mechanics & Astronomy) 2019年第10期62卷 24-32页

作者： Francesco Mallamace Carmelo Corsaro enza fazio Sow-Hsin Chen Domenico Mallamace Department of Nuclear Science and Engineering Massachusetts Institute of TechnologyCambridge MA 02139USA Center for Polymer Studies and Department of Physics Boston UniversityBoston MA 02215USA Dipartimento di Scienze Matematiche e Informatiche Scienze Fisiche e Scienze della Terra(MIFT)Universita di MessinaMessina 98166Italy

We study the hydrogen bonds effect on the water density as a function of temperature and pressure from the supercritical region to the metastable supercooled and amorphous phases. We identify two important thermodynamic thresholds, that is P~*■2 kbar and T~*■315 K, that separate two different water behaviors in terms of hydrogen bonding capability. For T < T~* and P < P~* the formation and stability of hydrogen bonded local structures are enhanced. The additional analyses of the proton NMR chemical shift and of the relaxation time confirm this evidence and highlight the structure breaking effects of the pressure. The investigation of both structural and dynamical quantities allow us to draw a complete picture of the water properties in terms of the temperaturepressure dependence of hydrogen bonding.

关键词： water hydrogen bond density critical supercooled phase

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Hydrophilic and hydrophobic competition in water-methanol solutions

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Science China(Physics,Mechanics & Astronomy) 2019年第10期62卷 8-15页

作者： Domenico Mallamace Sow-Hsin Chen Carmelo Corsaro enza fazio Francesco Mallamace HEugene Stanley Dipartimento MIFT Universita di MessinaMessina 1-98166Italy Department of Nuclear Science and Engineering Massachusetts Institute of TechnologyCambridge MA 02139USA Istituto dei Sistemi Complessi(ISC)-CNR Rome 00185Italy Center for Polymer Studies and Department of Physics Boston UniversityBoston MA 02215USA

We study the thermal behavior of the longitudinal spin-lattice, T1, and the transverse spin-spin, T2, relaxation times of the macroscopic magnetization in water/methanol solutions. Our aim is to investigate the reciprocal influence of hydrophobic effects on water properties and of hydrophilicity（via hydrogen bond, HB, interactions） on the solute. Using classical Nuclear Magnetic Resonance spectroscopy, we find a single characteristic correlation time τcthat reflects all local structural configurations and characterizes the thermal motion effects of the magnetic nuclei on the spin-spin interaction. We find that in the supercooled regime the correlations are stronger, with respect to ambient temperature, because the HB interactions have a lifetime long enough to sustain a stable water network. However, increasing the temperature, progressively decreases the HB interaction lifetime and destroys the water clusters with a consequent decoupling in the dynamic modes of the system. In addition, at temperatures higher than about 265 K, the hydrophobicity becomes gradually stronger and governs the physical properties of the solutions.

关键词： hydrophobic-hydrophilic interactions water systems thermal properties

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PEG-PLGA electrospun nanofibrous membranes loaded with Au@Fe2O3 nanoparticles for drug delivery applications

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Frontiers of physics 2018年第1期13卷 65-73页

作者： Salvatore Spadaro Marco Santoro Francesco Barreca Angela Scala Simona Grimato Fortunato Neri enza fazio Dipartimento di Scienze Matematiche e Informatiche Scienze Fisiche e Scienze della Terra Universita di Messina Viale F. Stagno D'Alcontres 31 98166 Messina Italy Dipartimento di Scienze Chimiche Biologiche Farmaceutiche e Ambientali Universita di Messina Viale F. Stagno D'Alcontres 31 98166 Messina Italy

A PEGylated-PLGA random nanofibrous membrane loaded with gold and iron oxide nanoparticles and with silibinin was prepared by electrospinning deposition. The nanofibrous membrane can be remotely controlled and activated by a laser light or magnetic field to release biological agents on demand. The nanosystems were characterized using scanning electron microscopy, Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, and thermogravimetric analyses. The drug loading efficiency and drug content percentages were determined by UV-vis optical absorption spectroscopy. The nanofibrous membrane irradiated by a relatively low-intensity laser or stimulated by a magnetic field showed sustained silibinin release for at least 60 h, without the burst effect. The proposed low-cost electrospinning procedure is capable of assembling, via a one-step procedure, a stimuli-responsive drug-loaded nanosystem with metallic nanoparticles to be externally activated for controlled drug delivery.

关键词： Au@Fe2O3 nanoparticles PEG-PLGA copolymer pulsed laser ablation electrospinning,drug delivery

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