1
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Vinhas S, Ivanova G, de Castro B, Rangel M. NMR and EPR study of the interaction of tris(3-hydroxy-4-pyridinonato) Ga(III) complexes with liposomes that mimic plant membranes. Biophys Chem 2023; 298:107021. [PMID: 37182237 DOI: 10.1016/j.bpc.2023.107021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 03/16/2023] [Accepted: 04/06/2023] [Indexed: 05/16/2023]
Abstract
We performed an NMR and EPR study of the interaction of four [Ga(3,4-HPO)3] chelates with liposomes derived from a soybean extract (SEL) and simpler formulations using POPC (100%) and POPE:POPC (50%). Parent [Fe(3,4-HPO)3] chelates are eligible to prevent Iron Deficiency Chlorosis and we took advantage of the likenesses of the ions Fe (III) and Ga (III), and the fact their metal ion complexes are isostructural, to perform a combined NMR and EPR study to get information about the permeation properties of the complexes. The results demonstrate the presence of liposomes loaded with Ga-chelates and that the distribution of complexes alongside the bilayer is dependent on their structure. Two compounds, [Ga(mpp)3] and [Ga(etpp)3], have a higher affinity for the polar region of the liposome bilayer thus suggesting that their structure facilitates their permanence at the root-rhizosphere interface. Chelates [Ga(dmpp)3] and [Ga(mrb13)3] interact with all types of protons of the lipid bilayer thus implying that they travel all along the bilayer structure indicating their higher permeation properties through soybean membranes. The results obtained for compound, [Ga(mrb13)3], which has been included in this work but was not yet tested in plant supplementation experiments, encourage its testing in in vivo plant studies once this study revealed that it interacts strongly with the model membranes. If the results of the future experiments in plants are positive and consistent with the present membrane-interaction studies the latter could constitute a good screening test for future compounds thus saving reagents and time.
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Affiliation(s)
- Sílvia Vinhas
- REQUIMTE, LAQV, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, 4069-007 Porto, Portugal
| | - Galya Ivanova
- REQUIMTE, LAQV, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, 4069-007 Porto, Portugal
| | - Baltazar de Castro
- REQUIMTE, LAQV, Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, 4069-007 Porto, Portugal
| | - Maria Rangel
- REQUIMTE, LAQV, Instituto de Ciências Biomédicas de Abel Salazar, Universidade do Porto, 4050-313 Porto, Portugal.
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2
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Ghiasi F, Eskandari MH, Golmakani MT, Rubio RG, Ortega F. Build-Up of a 3D Organogel Network within the Bilayer Shell of Nanoliposomes. A Novel Delivery System for Vitamin D 3: Preparation, Characterization, and Physicochemical Stability. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2021; 69:2585-2594. [PMID: 33617257 PMCID: PMC8478283 DOI: 10.1021/acs.jafc.0c06680] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The inherent thermodynamic instability of liposomes during production and storage has limited their widespread applications. Therefore, a novel structure of food-grade nanoliposomes stabilized by a 3D organogel network within the bilayer shell was developed through the extrusion process and successfully applied to encapsulate vitamin D3. A huge flocculation and a significant reduction of zeta potential (-17 mV) were observed in control nanoliposomes (without the organogel shell) after 2 months of storage at 4 °C, while the sample with a gelled bilayer showed excellent stability with a particle diameter of 105 nm and a high negative zeta potential (-63.4 mV), even after 3 months. The development of spherical vesicles was confirmed by TEM. Interestingly, the gelled bilayer shell led to improved stability against osmotically active divalent salt ions. Electron paramagnetic resonance confirmed the higher rigidity of the shell bilayer upon gelation. The novel liposome offered a dramatic increase in encapsulation efficiency and loading of vitamin D3 compared to those of control.
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Affiliation(s)
- Fatemeh Ghiasi
- Department
of Food Science and Technology, School of Agriculture, Shiraz University, Shiraz 71946-84636, Iran
| | - Mohammad Hadi Eskandari
- Department
of Food Science and Technology, School of Agriculture, Shiraz University, Shiraz 71946-84636, Iran
| | - Mohammad-Taghi Golmakani
- Department
of Food Science and Technology, School of Agriculture, Shiraz University, Shiraz 71946-84636, Iran
| | - Ramón G. Rubio
- Departamento
de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Ciudad Universitaria S/n, Madrid 28040, Spain
- Instituto
Pluridisciplinar, Universidad Complutense
de Madrid, Paseo Juan
XXIII 1, Madrid 28040, Spain
| | - Francisco Ortega
- Departamento
de Química Física, Facultad de Ciencias Químicas, Universidad Complutense de Madrid, Ciudad Universitaria S/n, Madrid 28040, Spain
- Instituto
Pluridisciplinar, Universidad Complutense
de Madrid, Paseo Juan
XXIII 1, Madrid 28040, Spain
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3
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Beg S, Almalki WH, Khatoon F, Alharbi KS, Alghamdi S, Akhter MH, Khalilullah H, Baothman AA, Hafeez A, Rahman M, Akhter S, Choudhry H. Lipid/polymer-based nanocomplexes in nucleic acid delivery as cancer vaccines. Drug Discov Today 2021; 26:1891-1903. [PMID: 33610757 DOI: 10.1016/j.drudis.2021.02.013] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 09/13/2020] [Accepted: 02/15/2021] [Indexed: 12/24/2022]
Abstract
Cancer vaccines consist of nucleic acid derivatives such as plasmid DNA, small interfering RNA and mRNA, and can be customized according to the patient's needs. Nanomedicines have proven to be exceptionally good as miniaturized drug carriers, and thus they offer great advantages for delivering cancer vaccines. This review provides an overview of the literature on cancer vaccines, from their inception to current developments in the field.
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Affiliation(s)
- Sarwar Beg
- Department of Pharmaceutics, School of Pharmaceutical Education and Research, Jamia Hamdard, New Delhi, India.
| | - Waleed H Almalki
- Department of Pharmacology and Toxicology, Faculty of Medicine, Umm Al-Qura University, Makkah, Saudi Arabia
| | - Fahmida Khatoon
- Department of Biochemistry, College of Medicine, University of Hail, Saudi Arabia
| | - Khalid S Alharbi
- Department of Pharmacology, College of Pharmacy, Jouf University, Sakakah, Saudi Arabia
| | - Saad Alghamdi
- Laboratory Medicine Department, Faculty of Applied Medical Sciences, Umm Al-Qura University, Makkah, Saudi Arabia
| | | | - Habibullah Khalilullah
- Department of Pharmaceutical Chemistry and Pharmacognosy, Unaizah College of Pharmacy, Qassim University, Saudi Arabia
| | - Abdullah A Baothman
- Ministry of National Guard-Health Affairs, King Saud Bin Abdulaziz University for Health Science (KSAU-HS), King Abdullah International Medical Research Center (KAIMARC), Saudi Arabia
| | - Abdul Hafeez
- Glocal School of Pharmacy, Glocal University, Mirzapur Pole, Sahranpur, Uttar Pradesh, India
| | - Mahfoozur Rahman
- Department of Pharmaceutical Sciences, SIHAS, Faculty of Health Science, Sam Higginbottom University of Agriculture, Technology and Sciences, Allahabad, India.
| | - Sohail Akhter
- New Product Development, Global R&D, Sterile ops, TEVA Pharmaceutical Industries Ltd., Aston Ln N, Halton, Preston Brook, Runcorn WA7 3FA, UK; Centre de Biophysique Moléculaire, CNRS UPR4301, Rue Charles Sadron, 45071 Orléans Cedex 2, France
| | - Hani Choudhry
- Department of Biochemistry, Cancer Metabolism & Epigenetic Unit, Faculty of Science, King Fahd Center for Medical Research, King Abdulaziz University, Jeddah, Saudi Arabia
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4
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Akdogan Y, Emrullahoglu M, Tatlidil D, Ucuncu M, Cakan-Akdogan G. EPR studies of intermolecular interactions and competitive binding of drugs in a drug-BSA binding model. Phys Chem Chem Phys 2018; 18:22531-9. [PMID: 27468942 DOI: 10.1039/c6cp04137j] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Understanding intermolecular interactions between drugs and proteins is very important in drug delivery studies. Here, we studied different binding interactions between salicylic acid and bovine serum albumin (BSA) using electron paramagnetic resonance (EPR) spectroscopy. Salicylic acid was labeled with a stable radical (spin label) in order to monitor its mobilized (free) or immobilized (bound to BSA) states. In addition to spin labeled salicylic acid (SL-salicylic acid), its derivatives including SL-benzoic acid, SL-phenol, SL-benzene, SL-cyclohexane and SL-hexane were synthesized to reveal the effects of various drug binding interactions. EPR results of these SL-molecules showed that hydrophobic interaction is the main driving force. Whereas each of the two functional groups (-COOH and -OH) on the benzene ring has a minute but detectable effect on the drug-protein complex formation. In order to investigate the effect of electrostatic interaction on drug binding, cationic BSA (cBSA) was synthesized, altering the negative net charge of BSA to positive. The salicylic acid loading capacity of cBSA is significantly higher compared to that of BSA, indicating the importance of electrostatic interaction in drug binding. Moreover, the competitive binding properties of salicylic acid, ibuprofen and aspirin to BSA were studied. The combined EPR results of SL-salicylic acid/ibuprofen and SL-ibuprofen/salicylic acid showed that ibuprofen is able to replace up to ∼83% of bound SL-salicylic acid, and salicylic acid can replace only ∼14% of the bound SL-ibuprofen. This indicates that ∼97% of all salicylic acid and ibuprofen binding sites are shared. On the other hand, aspirin replaces only ∼23% of bound SL-salicylic acid, and salicylic acid replaces ∼50% of bound SL-aspirin, indicating that ∼73% of all salicylic acid and aspirin binding sites are shared. These results show that EPR spectroscopy in combination with the spin labeling technique is a very powerful method to investigate drug binding dynamics in detail.
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Affiliation(s)
- Y Akdogan
- Materials Science and Engineering Department, I[combining dot above]zmir Institute of Technology, 35430 Urla, I[combining dot above]zmir, Turkey.
| | - M Emrullahoglu
- Department of Chemistry, I[combining dot above]zmir Institute of Technology, 35430 Urla, I[combining dot above]zmir, Turkey
| | - D Tatlidil
- Materials Science and Engineering Department, I[combining dot above]zmir Institute of Technology, 35430 Urla, I[combining dot above]zmir, Turkey.
| | - M Ucuncu
- Department of Chemistry, I[combining dot above]zmir Institute of Technology, 35430 Urla, I[combining dot above]zmir, Turkey
| | - G Cakan-Akdogan
- Dokuz Eylul University, I[combining dot above]zmir Biomedicine and Genome Center, I[combining dot above]zmir, Turkey
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5
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Localization of dexamethasone within dendritic core-multishell (CMS) nanoparticles and skin penetration properties studied by multi-frequency electron paramagnetic resonance (EPR) spectroscopy. Eur J Pharm Biopharm 2017; 116:94-101. [DOI: 10.1016/j.ejpb.2016.10.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Revised: 09/30/2016] [Accepted: 10/12/2016] [Indexed: 12/27/2022]
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6
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Influence of water concentrations on the phase transformation of a model surfactant/co-surfactant/water system. Chem Phys 2017. [DOI: 10.1016/j.chemphys.2016.11.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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7
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Ramezanpour M, Leung SSW, Delgado-Magnero KH, Bashe BYM, Thewalt J, Tieleman DP. Computational and experimental approaches for investigating nanoparticle-based drug delivery systems. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:1688-709. [PMID: 26930298 DOI: 10.1016/j.bbamem.2016.02.028] [Citation(s) in RCA: 105] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2016] [Revised: 02/20/2016] [Accepted: 02/23/2016] [Indexed: 12/21/2022]
Abstract
Most therapeutic agents suffer from poor solubility, rapid clearance from the blood stream, a lack of targeting, and often poor translocation ability across cell membranes. Drug/gene delivery systems (DDSs) are capable of overcoming some of these barriers to enhance delivery of drugs to their right place of action, e.g. inside cancer cells. In this review, we focus on nanoparticles as DDSs. Complementary experimental and computational studies have enhanced our understanding of the mechanism of action of nanocarriers and their underlying interactions with drugs, biomembranes and other biological molecules. We review key biophysical aspects of DDSs and discuss how computer modeling can assist in rational design of DDSs with improved and optimized properties. We summarize commonly used experimental techniques for the study of DDSs. Then we review computational studies for several major categories of nanocarriers, including dendrimers and dendrons, polymer-, peptide-, nucleic acid-, lipid-, and carbon-based DDSs, and gold nanoparticles. This article is part of a Special Issue entitled: Membrane Proteins edited by J.C. Gumbart and Sergei Noskov.
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Affiliation(s)
- M Ramezanpour
- Centre for Molecular Simulation, Department of Biological Sciences, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - S S W Leung
- Department of Physics, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - K H Delgado-Magnero
- Centre for Molecular Simulation, Department of Biological Sciences, University of Calgary, Calgary, AB T2N 1N4, Canada
| | - B Y M Bashe
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - J Thewalt
- Department of Physics, Simon Fraser University, Burnaby, BC V5A 1S6, Canada; Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
| | - D P Tieleman
- Centre for Molecular Simulation, Department of Biological Sciences, University of Calgary, Calgary, AB T2N 1N4, Canada
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8
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Venkatesh V, Wedge CJ, Romero-Canelón I, Habtemariam A, Sadler PJ. Spin-labelled photo-cytotoxic diazido platinum(iv) anticancer complex. Dalton Trans 2016; 45:13034-7. [DOI: 10.1039/c6dt01382a] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
We report the synthesis and characterisation of the nitroxide spin-labelled photoactivatable Pt(iv) prodrugtrans,trans,trans-[Pt(N3)2(OH)(OCOCH2CH2CONH-TEMPO)(Py)2] (Pt-TEMPO).
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Affiliation(s)
- V. Venkatesh
- Department of Chemistry
- University of Warwick
- Coventry CV4 7AL
- UK
| | | | | | | | - Peter J. Sadler
- Department of Chemistry
- University of Warwick
- Coventry CV4 7AL
- UK
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9
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Leong WF, Berton-Carabin CC, Elias RJ, Lecomte J, Villeneuve P, Zhao Y, Coupland JN. Effect of lipophilization on the distribution and reactivity of ingredients in emulsions. J Colloid Interface Sci 2015; 459:36-43. [DOI: 10.1016/j.jcis.2015.07.070] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2014] [Revised: 07/28/2015] [Accepted: 07/30/2015] [Indexed: 11/29/2022]
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10
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Falsini S, Ciani L, Arcangeli A, Di Cola E, Spinozzi F, Ristori S. Physico-chemical properties of gemini micelles studied by X-ray scattering and ESR spectroscopy. Colloids Surf A Physicochem Eng Asp 2015. [DOI: 10.1016/j.colsurfa.2015.02.034] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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11
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Tatlidil D, Ucuncu M, Akdogan Y. Physiological concentrations of albumin favor drug binding. Phys Chem Chem Phys 2015; 17:22678-85. [DOI: 10.1039/c5cp03583j] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We exploit the direct measurements of spin labeled drugs to study drug binding to/release from protein using EPR spectroscopy.
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Affiliation(s)
- D. Tatlidil
- Materials Science and Engineering Department
- Ízmir Institute of Technology
- Ízmir
- Turkey
| | - M. Ucuncu
- Department of Chemistry
- Ízmir Institute of Technology
- Ízmir
- Turkey
| | - Y. Akdogan
- Materials Science and Engineering Department
- Ízmir Institute of Technology
- Ízmir
- Turkey
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12
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Localization and reactivity of a hydrophobic solute in lecithin and caseinate stabilized solid lipid nanoparticles and nanoemulsions. J Colloid Interface Sci 2013; 394:20-5. [DOI: 10.1016/j.jcis.2012.12.042] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2012] [Revised: 12/12/2012] [Accepted: 12/13/2012] [Indexed: 11/20/2022]
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13
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Kurzbach D, Junk MJN, Hinderberger D. Nanoscale Inhomogeneities in Thermoresponsive Polymers. Macromol Rapid Commun 2012; 34:119-34. [DOI: 10.1002/marc.201200617] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Revised: 10/16/2012] [Indexed: 12/11/2022]
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14
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Kurzbach D, Schömer M, Wilms VS, Frey H, Hinderberger D. How Structure-Related Collapse Mechanisms Determine Nanoscale Inhomogeneities in Thermoresponsive Polymers. Macromolecules 2012. [DOI: 10.1021/ma3014299] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Dennis Kurzbach
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz,
Germany
| | - Martina Schömer
- Department of Organic
Chemistry, Johannes Gutenberg-University Mainz, Duesbergweg 10-14,
55128 Mainz, Germany
| | - Valerie S. Wilms
- Department of Organic
Chemistry, Johannes Gutenberg-University Mainz, Duesbergweg 10-14,
55128 Mainz, Germany
- Graduate School “Materials Science in Mainz”, Staudingerweg 9, 55099 Mainz,
Germany
| | - Holger Frey
- Department of Organic
Chemistry, Johannes Gutenberg-University Mainz, Duesbergweg 10-14,
55128 Mainz, Germany
| | - Dariush Hinderberger
- Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz,
Germany
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15
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Kurzbach D, Reh MN, Hinderberger D. Nanoscale Inhomogeneities in Thermoresponsive Triblock Copolymers. Chemphyschem 2011; 12:3566-72. [DOI: 10.1002/cphc.201100474] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Indexed: 11/08/2022]
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16
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Cherstvy AG. Electrostatic interactions in biological DNA-related systems. Phys Chem Chem Phys 2011; 13:9942-68. [DOI: 10.1039/c0cp02796k] [Citation(s) in RCA: 120] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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17
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Yu JS, Wu FG, Tao LF, Luo JJ, Yu ZW. Mechanism of the fast exchange between bound and free guests in cucurbit[7]uril–guest systems. Phys Chem Chem Phys 2011; 13:3638-41. [DOI: 10.1039/c0cp02349c] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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18
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Cong H, Zhu Q, Xue S, Tao Z, Wei G. Direct coordination of metal ions to cucurbit[n]urils. ACTA ACUST UNITED AC 2010. [DOI: 10.1007/s11434-010-4146-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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19
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Peptide and glycopeptide dendrimers and analogous dendrimeric structures and their biomedical applications. Amino Acids 2010; 40:301-70. [DOI: 10.1007/s00726-010-0707-z] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Accepted: 07/15/2010] [Indexed: 02/08/2023]
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20
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Lucarini M, Pasquato L. ESR spectroscopy as a tool to investigate the properties of self-assembled monolayers protecting gold nanoparticles. NANOSCALE 2010; 2:668-676. [PMID: 20648307 DOI: 10.1039/b9nr00384c] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Electron spin resonance (ESR) has emerged as a powerful spectroscopic technique to study the properties of metal nanoparticles (NPs) protected by a self-assembled monolayer (SAM) of organic molecules. This technique has been employed to explore the capacity of homoligand monolayers to bind to a hydrophobic probe or to "sense" the hydrophobicity of mixed-ligand monolayers. Moreover, spin labels anchored to the metal surface enable the investigation of the dynamic of the ligands that form the monolayer. Here we review these applications with the aim of unravelling the many features of monolayer-protected metal NPs.
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Affiliation(s)
- Marco Lucarini
- Department of Organic Chemistry A. Mangini, University of Bologna, via San Giacomo 11, I-40126, Bologna, Italy.
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21
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Dzikovski B, Tipikin D, Livshits V, Earle K, Freed J. Multifrequency ESR study of spin-labeled molecules in inclusion compounds with cyclodextrins. Phys Chem Chem Phys 2009; 11:6676-88. [PMID: 19639141 DOI: 10.1039/b903490k] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The molecular dynamics of spin-labeled compounds included into the solid phase of cyclodextrins (CDs) has been studied using conventional (X-band) ESR at 9 GHz and high-field high-frequency (HFHF) ESR at 240 and 170 GHz. The patterns of axial rotation at these higher frequencies are clear just by inspection of the spectrum, unlike the case for 9 GHz spectra. That is HFHF ESR is sensitive to molecular motion about the diffusion axis collinear with the X, Y or Z-direction of the magnetic g- and A-tensors of the nitroxide moiety (referred to, respectively, as X, Y or Z-rotation). For doxyl stearic acids (Z-rotation) and TEMPOyl caprylate (X-rotation) included in beta- and gamma-CDs we were able to determine the rate of molecular motion and the corresponding potential barriers. We emphasize that determining the rate of Z-rotation by ESR is feasible only using HFHF ESR. For the X-rotation case we suggest that the motion of the nitroxide moiety consists of fast small-angle librations about the magnetic X-axis superimposed by rotational diffusion about the same axis. The potential barrier of 1.7 Kcal mol(-1) for this rotational diffusion is unusually low. A fascinating feature of TEMPO derivatives included in beta-CD is the detectable molecular motion at temperatures below 77 K. For the other CD-spin probe systems, we used multifrequency analysis to assign the conformations of spin-labeled molecules. A dramatic spectral change for 16-sasl in beta- and gamma-CDs at approximately 260 K corresponds to a tilting of the position of the nitroxide moiety on the rotating molecule relative to the long diffusion axis, while for TEMPO derivatives in gamma-cyclodextrin below 200 K, we observe a rapid transition from fast to very slow rotational motion. More complex features are best studied by means of multifrequency ESR experiments. The visual clarity and the simplicity of analysis of the ESR spectra shown in this work should provide a benchmark for future studies of molecular motion by HFHF ESR.
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Affiliation(s)
- Boris Dzikovski
- Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA
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