1
|
Franzè S, Selmin F, Rocco P, Colombo G, Casiraghi A, Cilurzo F. Preserving the Integrity of Liposomes Prepared by Ethanol Injection upon Freeze-Drying: Insights from Combined Molecular Dynamics Simulations and Experimental Data. Pharmaceutics 2020; 12:pharmaceutics12060530. [PMID: 32526935 PMCID: PMC7356173 DOI: 10.3390/pharmaceutics12060530] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2020] [Revised: 06/04/2020] [Accepted: 06/05/2020] [Indexed: 11/17/2022] Open
Abstract
The freeze-drying of complex formulations, such as liposomes, is challenging, particularly if dispersions contain residual organic solvents. This work aimed to investigate the effects of possible protectants, namely sucrose, trehalose and/or poly(vinyl pyrrolidone) (PVP), on the main features of the dried product using a 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC)-based liposomal dispersion prepared by ethanol injection and containing ethanol up to 6%, as a model. The interactions among vesicles and protectants were preliminary screened by Molecular Dynamics (MD) simulations, which have been proved useful in rationalizing the selection of protectant(s). The freeze-drying protocol was based on calorimetric results. Overall data suggested a stronger cryo-protectant effect of trehalose, compared with sucrose, due to stronger interactions with the DPPC bilayer and the formation of highly ordered clusters around the lipids. The effect further improved in the presence of PVP. Differently from the other tested protectants, the selected trehalose/PVP combination allows to preserve liposome size, even in the presence of 6% ethanol, as demonstrated by Nanoparticle Tracking Analysis (NTA). Nevertheless, it should be also underlined that cakes blew out at an ethanol concentration higher than 1% v/v, probably due to the poor cohesion within the cake and solvent vapour pressure upon sublimation.
Collapse
Affiliation(s)
- Silvia Franzè
- Department of Pharmaceutical Sciences, University of Milan, Via G. Colombo 71, 20133 Milan, Italy; (S.F.); (P.R.); (A.C.); (F.C.)
| | - Francesca Selmin
- Department of Pharmaceutical Sciences, University of Milan, Via G. Colombo 71, 20133 Milan, Italy; (S.F.); (P.R.); (A.C.); (F.C.)
- Correspondence: ; Tel.: +39-02-503-24645
| | - Paolo Rocco
- Department of Pharmaceutical Sciences, University of Milan, Via G. Colombo 71, 20133 Milan, Italy; (S.F.); (P.R.); (A.C.); (F.C.)
| | | | - Antonella Casiraghi
- Department of Pharmaceutical Sciences, University of Milan, Via G. Colombo 71, 20133 Milan, Italy; (S.F.); (P.R.); (A.C.); (F.C.)
| | - Francesco Cilurzo
- Department of Pharmaceutical Sciences, University of Milan, Via G. Colombo 71, 20133 Milan, Italy; (S.F.); (P.R.); (A.C.); (F.C.)
| |
Collapse
|
2
|
Mason PE, Tavagnacco L, Saboungi ML, Hansen T, Fischer HE, Neilson GW, Ichiye T, Brady JW. Molecular Dynamics and Neutron Scattering Studies of Potassium Chloride in Aqueous Solution. J Phys Chem B 2019; 123:10807-10813. [PMID: 31769976 DOI: 10.1021/acs.jpcb.9b08422] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Neutron diffraction with isotopic substitution (NDIS) experiments were done on both natural abundance potassium and isotopically labeled 41KCl heavy water solutions to characterize the solvent structuring around the potassium ion in water. Preliminary measurements suggested that the literature value for the coherent neutron scattering length (2.69 fm) for 41K was significantly in error. This value was remeasured using a neutron powder diffractometer and found to be 2.40 fm. This revision increases significantly the contrast between the natural abundance K and 41K by about 30% (from 1.0 to 1.3 fm). The experimentally determined structure factor of the potassium ion was then compared to that calculated from molecular dynamics (MD) simulations. Previous neutron scattering measurements of potassium gave a solvation number of 5.5 (see below). In this study, the NDIS and MD results are in good agreement and allowed us to derive a coordination number of 6.1 for water molecules and 0.8 for chloride ions around each K+ ion in 4 molal aqueous KCl solution.
Collapse
Affiliation(s)
- Philip E Mason
- Institute of Organic Chemistry and Biochemistry , Academy of Sciences of the Czech Republic & Center for Biomolecules and Complex Molecular Systems , 16610 Prague 6 , Czech Republic
| | - Letizia Tavagnacco
- Department of Food Science , Cornell University , Ithaca , New York 14853 , United States
| | - Marie-Louise Saboungi
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie , UMR 7590 CNRS - Sorbonne Université, Campus Pierre et Marie Curie , 4, Place Jussieu , 75005 Paris , France
| | - Thomas Hansen
- Institut Laue-Langevin , 71 Avenue des Martyrs , 38042 Grenoble Cedex 9 , France
| | - Henry E Fischer
- Institut Laue-Langevin , 71 Avenue des Martyrs , 38042 Grenoble Cedex 9 , France
| | - George W Neilson
- H.H. Wills Physics Laboratory , University of Bristol , BS8 1TL Bristol , U.K
| | - Toshiko Ichiye
- Department of Chemistry , Georgetown University , Box 571227, Washington , DC 20057 , United States
| | - John W Brady
- Department of Food Science , Cornell University , Ithaca , New York 14853 , United States
| |
Collapse
|
3
|
|
4
|
Affiliation(s)
- Mario Orsi
- School of Engineering and Materials Science, Queen Mary University of London, London, UK
| |
Collapse
|
5
|
Abstract
Many quantum mechanical calculations indicate water molecules in the gas and liquid phase have much larger quadrupole moments than any of the common site models of water for computer simulations. Here, comparisons of multipoles from quantum mechanical∕molecular mechanical (QM∕MM) calculations at the MP2∕aug-cc-pVQZ level on a B3LYP∕aug-cc-pVQZ level geometry of a waterlike cluster and from various site models show that the increased square planar quadrupole can be attributed to the p-orbital character perpendicular to the molecular plane of the highest occupied molecular orbital as well as a slight shift of negative charge toward the hydrogens. The common site models do not account for the p-orbital type electron density and fitting partial charges of TIP4P- or TIP5P-type models to the QM∕MM dipole and quadrupole give unreasonable higher moments. Furthermore, six partial charge sites are necessary to account reasonably for the large quadrupole, and polarizable site models will not remedy the problem unless they account for the p-orbital in the gas phase since the QM calculations show it is present there too. On the other hand, multipole models by definition can use the correct multipoles and the electrostatic potential from the QM∕MM multipoles is much closer than that from the site models to the potential from the QM∕MM electron density. Finally, Monte Carlo simulations show that increasing the quadrupole in the soft-sticky dipole-quadrupole-octupole multipole model gives radial distribution functions that are in good agreement with experiment.
Collapse
Affiliation(s)
- Shuqiang Niu
- Department of Chemistry, Georgetown University, Washington, DC 20057, USA
| | | | | |
Collapse
|
6
|
Te JA, Ichiye T. UNDERSTANDING STRUCTURAL EFFECTS OF MULTIPOLE MOMENTS ON AQUEOUS SOLVATION OF IONS USING THE SOFT-STICKY DIPOLE-QUADRUPOLE-OCTUPOLE WATER MODEL. Chem Phys Lett 2010; 499:219-225. [PMID: 21072252 DOI: 10.1016/j.cplett.2010.09.043] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The effects of water multipole moments on the aqueous solvation of ions were determined in Monte Carlo simulations using soft-sticky dipole-quadrupole-octupole (SSDQO) water. Water molecules formed linear hydrogen bonds to Cl(-) using the new SSDQO1 parameters, similar to multi-site models. However, the dipole vector was tilted rather than parallel to the oxygen-Na(+) internuclear vector as in most multi-site model, while experiment and ab initio molecular dynamics simulations generally indicate a range of values between tilted and parallel. By varying the multipoles in SSDQO, the octupole was found to determine the orientation around Na(+). Moreover, analysis of the multipoles of more conventional models is predictive of their performance as solvents.
Collapse
Affiliation(s)
- Jerez A Te
- Department of Chemistry, Georgetown University, Washington, DC, 20057
| | | |
Collapse
|
7
|
Te JA, Ichiye T. Temperature and pressure dependence of the optimized soft-sticky dipole-quadrupole-octupole water model. J Chem Phys 2010; 132:114511. [PMID: 20331309 DOI: 10.1063/1.3359432] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The soft-sticky dipole-quadrupole-octupole (SSDQO) potential energy function for a coarse-grained single-site water model has Lennard-Jones interactions and an approximate multipole expansion for the electrostatics. Here, the Lennard-Jones parameters and multipole moments of SSDQO were optimized so that the structural, thermodynamic, dynamic, and dielectric properties agreed with experimental values of liquid water at ambient conditions. Using these parameters, the temperature and pressure dependence of various properties were shown to be in good agreement with experiment, including a temperature of maximum density at approximately 260 K. This new parametrization, referred to as SSDQO1, is both computationally faster and generally more accurate over a wide range of conditions than traditional three-site water models, which demonstrates that a model with a single dipole, quadrupole, and octupole on each water molecule can reproduce the tetrahedral hydrogen bonded network of water.
Collapse
Affiliation(s)
- Jerez A Te
- Department of Chemistry, Georgetown University, Washington, DC 20057, USA
| | | |
Collapse
|
8
|
Te JA, Tan ML, Ichiye T. Solvation of Glucose, Trehalose, and Sucrose by the Soft Sticky Dipole-Quadrupole-Octupole Water Model. Chem Phys Lett 2010; 491:218-223. [PMID: 21072255 PMCID: PMC2975465 DOI: 10.1016/j.cplett.2010.04.020] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Water structure around sugars modeled by partial charges is compared for soft-sticky dipole-quadrupole-octupole (SSDQO), a fast single-site multipole model, and commonly used multi-site models in Monte Carlo simulations. Radial distribution functions and coordination numbers of all the models indicate similar hydration by hydrogen-bond donor and acceptor waters. However, the new optimized SSDQO1 parameters as well as TIP4P-Ew and TIP5P predict a "lone-pair" orientation for the water accepting the sugar hydroxyl hydrogen bond that is more consistent with the limited experimental data than the "dipole" orientation in SPC/E, which has important implications for studies of the cryoprotectant properties of sugars.
Collapse
Affiliation(s)
- Jerez A. Te
- Department of Chemistry, Georgetown University, Washington, DC, 20057
| | - Ming-Liang Tan
- Department of Chemistry, Georgetown University, Washington, DC, 20057
| | - Toshiko Ichiye
- Department of Chemistry, Georgetown University, Washington, DC, 20057
| |
Collapse
|