1
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Forte G, Consiglio G, Satriano C, Maugeri L, Petralia S. A nanosized photothermal responsive core-shell carbonized polymer dots based on poly(N-isopropylacrylamide) for light-triggered drug release. Colloids Surf B Biointerfaces 2022; 217:112628. [PMID: 35716451 DOI: 10.1016/j.colsurfb.2022.112628] [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: 03/19/2022] [Revised: 06/08/2022] [Accepted: 06/11/2022] [Indexed: 11/28/2022]
Abstract
Core-shell nanocomposites are one of the most important achievements in the fast-growing field of nanotechnology. The combination of multi-responsive nano-shell with luminescent and photothermal core has led to promising applications in various fields such as optics, electronics and medicine. In this work, a nanosized core-shell system composed by carbonized dots core and poly(N-isopropylacrylamide) shell was developed and the photothermal triggered release of doxorubicin was demonstrated. The system was fully characterized by H1-NMR, DLS, Z-potential, AFM, optical absorption and fluorescence measurements. A photothermal conversion efficiency (η) value of about 67.9% and a doxorubicin photo-release rate value of about 1.0% min-1 were measured. Molecular dynamic (MD) simulations data were in agreement with experimental results, at 310 K the coil-to-globule transition and a consequent desorption of doxorubicin from the polymer were observed. Both the radius of gyration and the fluctuation of the distance doxorubicin-PNIPAM pointed that the temperature above the LCST and the acid pH facilitated the polymer transition. Moreover, MD simulations and experimental data suggested an influence on the lower critical solution temperature (LCST) exerted by the number of polymer chains anchored to the carbon core.
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Affiliation(s)
- Giuseppe Forte
- Department of Drug Science and Health, University of Catania, Via S. Sofia, 64, 95125 Catania, Italy.
| | - Giuseppe Consiglio
- Department of Chemical Science, University of Catania, Via S. Sofia, 64, 95125 Catania, Italy
| | - Cristina Satriano
- Department of Chemical Science, University of Catania, Via S. Sofia, 64, 95125 Catania, Italy
| | - Ludovica Maugeri
- A.O.U Policlinico "G. Rodolico San Marco", Via S. Sofia, 5125 Catania, Italy
| | - Salvatore Petralia
- Department of Drug Science and Health, University of Catania, Via S. Sofia, 64, 95125 Catania, Italy.
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2
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Yang XD, Chen W, Ren Y, Chu LY. Exploring dielectric spectra of polymer through molecular dynamics simulations. MOLECULAR SIMULATION 2022. [DOI: 10.1080/08927022.2022.2083122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Xue-Dan Yang
- School of Chemical Engineering, Sichuan University, Chengdu, Sichuan, People's Republic of China
- State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, Sichuan, People's Republic of China
- State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Wei Chen
- State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, People's Republic of China
- University of Chinese Academy of Sciences, Beijing, People's Republic of China
- Dalian National Laboratory for Clean Energy, Chinese Academy of Sciences, Dalian, Liaoning, People's Republic of China
| | - Ying Ren
- State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, People's Republic of China
- University of Chinese Academy of Sciences, Beijing, People's Republic of China
- Innovation Academy for Green Manufacture, Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Liang-Yin Chu
- School of Chemical Engineering, Sichuan University, Chengdu, Sichuan, People's Republic of China
- State Key Laboratory of Polymer Materials Engineering, Sichuan University, Chengdu, Sichuan, People's Republic of China
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3
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Narang P, de Oliveira TE, Venkatesu P, Netz PA. The role of osmolytes in the temperature-triggered conformational transition of poly(N-vinylcaprolactam): an experimental and computational study. Phys Chem Chem Phys 2020; 22:5301-5313. [PMID: 32096507 DOI: 10.1039/c9cp06683g] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Biomedical industries are widely exploring the use of thermo-responsive polymers (TRPs) in the advanced development of drug delivery and in many other pharmaceutical applications. There is a great need to investigate the use of less toxic and more (bio-)compatible TRPs employing several additives, which could modify the conformational transition behavior of TRPs in aqueous solution. To move forward in this aspect, we have chosen the less toxic bio-based polymer poly(N-vinylcaprolactam) (PVCL) and three different methylamine-based osmolytes, trimethylamine N-oxide (TMAO), betaine and sarcosine, in order to investigate their particular interactions with the polymer segments in PVCL and therefore the corresponding changes in the thermo-responsive conformational behavior. Several biophysical techniques, UV-visible spectroscopy, fluorescence spectroscopy, dynamic light scattering (DLS) and laser Raman spectroscopy, as well as classical computer simulation methods such as molecular dynamics are employed in the current work. All the studied methylamines are found to favor the hydrophobic collapse of the polymer thus stabilizing the globular state of PVCL. Sarcosine is observed to cause the maximum decrease in lower critical solution temperature (LCST) of PVCL followed by TMAO and then betaine. The differences observed in the LCST values of PVCL in the presence of these molecules can be attributed to the different polymer-osmolyte interactions. The less sterically hindered N atom in the case of sarcosine causes a significant difference in the phase transition temperature values of PVCL compared to betaine and TMAO, where the nitrogen atom is buried by three methyl groups attached to it.
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Affiliation(s)
- Payal Narang
- Department of Chemistry, University of Delhi, Delhi-110007, India.
| | | | | | - Paulo A Netz
- Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
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4
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Ortiz de Solorzano I, Bejagam KK, An Y, Singh SK, Deshmukh SA. Solvation dynamics of N-substituted acrylamide polymers and the importance for phase transition behavior. SOFT MATTER 2020; 16:1582-1593. [PMID: 31951239 DOI: 10.1039/c9sm01798d] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Functional groups present in thermo-responsive polymers are known to play an important role in aqueous solutions by manifesting their coil-to-globule conformational transition in a specific temperature range. Understanding the role of these functional groups and their interactions with water is of great interest as it may allow us to control both the nature and temperature of this coil-to-globule transition. In this work, polyacrylamide (PAAm), poly(N-isopropylacrylamide) (PNIPAm), and poly(N-isopropylmethacrylamide) (PNIPMAm) solvated in water are studied with the goal of discovering the structure of the solvent and its interaction with these polymers in determining the polymer conformations. Specifically, all-atom molecular dynamics (MD) simulations were performed on polymer chains with 30 monomer units (30-mers) at 295 K, 310 K and 320 K, which is below and above the lower critical solution temperature (LCST) of PNIPAm (LCST = 305 K) and PNIPMAm (LCST = 315 K), respectively. The MD simulation trajectories suggest that changes in the functional groups in the backbone and side-chains alter the water solvation shell around the polymer. This results in a change in the residence time probability and hydrogen bond characteristics of water at simulated temperatures. Specifically, water molecules reside for longer times near PAAm (no LCST) and PNIPMAm (LCST = 315 K) chains as compared to PNIPAm. This might be one of the possible causes for the higher LCST of PNIPMAm as compared to that of PNIPAm. These results can guide experimentalists and theoreticians to design new polymer structures with tailor-made LCST transitions while controlling the water solvation shell around the functional group.
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Affiliation(s)
- Isabel Ortiz de Solorzano
- Department of Chemical Engineering, Aragon Institute of Nanoscience (INA), University of Zaragoza, Campus Río Ebro-Edificio I+D, C/Poeta Mariano Esquillor S/N, 50018-Zaragoza, Spain
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5
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Li C, Qin Z, Han W. Bottom-up derived flexible water model with dipole and quadrupole moments for coarse-grained molecular simulations. Phys Chem Chem Phys 2020; 22:27394-27412. [DOI: 10.1039/d0cp04185h] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A bottom-up CG water model is developed to capture the electrostatic multipoles, structural correlation and thermodynamics of water.
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Affiliation(s)
- Chen Li
- State Key Laboratory of Chemical Genomics
- School of Chemical Biology and Biotechnology
- Peking University Shenzhen Graduate School
- Shenzhen
- China
| | - Zhongyuan Qin
- State Key Laboratory of Chemical Genomics
- School of Chemical Biology and Biotechnology
- Peking University Shenzhen Graduate School
- Shenzhen
- China
| | - Wei Han
- State Key Laboratory of Chemical Genomics
- School of Chemical Biology and Biotechnology
- Peking University Shenzhen Graduate School
- Shenzhen
- China
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6
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Bejagam KK, Singh SK, Ahn R, Deshmukh SA. Unraveling the Conformations of Backbone and Side Chains in Thermosensitive Bottlebrush Polymers. Macromolecules 2019. [DOI: 10.1021/acs.macromol.9b01021] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Karteek K. Bejagam
- Department of Chemical Engineering, Virginia Tech, Blacksburg, Virginia 24061, United States
| | | | - Rebecca Ahn
- Department of Chemical Engineering, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Sanket A. Deshmukh
- Department of Chemical Engineering, Virginia Tech, Blacksburg, Virginia 24061, United States
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7
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Podewitz M, Wang Y, Quoika PK, Loeffler JR, Schauperl M, Liedl KR. Coil-Globule Transition Thermodynamics of Poly( N-isopropylacrylamide). J Phys Chem B 2019; 123:8838-8847. [PMID: 31545046 DOI: 10.1021/acs.jpcb.9b06125] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Thermosensitive polymers such as poly(N-isopropylacrylamide) (PNIPAM) undergo a phase transition in aqueous solution from a random-coil structural ensemble to a globule structural ensemble at the lower critical solution temperature (LCST). Above this temperature, PNIPAM agglomerates and becomes insoluble, whereas it is soluble below the temperature. Thus, thermosensitive polymers represent essential targets for several applications, e.g., in drug delivery. Although their ability to change structure in response to a temperature alteration is highly relevant for industrial processes, their thermodynamic properties are mostly qualitatively understood, and the quantitative thermodynamic picture is still elusive. In this study, we used a combined atomistic molecular dynamics and well-tempered metadynamics simulation approach to estimate coil-globule transition thermodynamics. An isotactic 30-mer of PNIPAM was investigated over a broad temperature range between 200 and 360 K. The transition from the globule to the random-coil structure was observed with well-tempered metadynamics. For the first time, the free energy surface of PNIPAM was estimated and it is shown that the simulation results are in line with the experimentally observed thermosensitive behavior. Below the LCST, the random-coil ensemble represents the global energy minimum and is thermodynamically favored by 21 ± 9 kJ/mol compared to the globule ensemble; both are separated by a barrier of 49 ± 14 kJ/mol. In contrast, above the LCST, the globule ensemble is thermodynamically favored by 21 ± 8 kJ/mol over the random-coil ensemble. The barrier from random-coil to globule is 17 ± 10 kJ/mol.
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Affiliation(s)
- Maren Podewitz
- Institute of General, Inorganic and Theoretical Chemistry, and Center for Molecular Biosciences Innsbruck (CMBI) , University of Innsbruck , Innrain 80-82 , A-6020 Innsbruck , Austria
| | - Yin Wang
- Institute of General, Inorganic and Theoretical Chemistry, and Center for Molecular Biosciences Innsbruck (CMBI) , University of Innsbruck , Innrain 80-82 , A-6020 Innsbruck , Austria
| | - Patrick K Quoika
- Institute of General, Inorganic and Theoretical Chemistry, and Center for Molecular Biosciences Innsbruck (CMBI) , University of Innsbruck , Innrain 80-82 , A-6020 Innsbruck , Austria
| | - Johannes R Loeffler
- Institute of General, Inorganic and Theoretical Chemistry, and Center for Molecular Biosciences Innsbruck (CMBI) , University of Innsbruck , Innrain 80-82 , A-6020 Innsbruck , Austria
| | - Michael Schauperl
- Institute of General, Inorganic and Theoretical Chemistry, and Center for Molecular Biosciences Innsbruck (CMBI) , University of Innsbruck , Innrain 80-82 , A-6020 Innsbruck , Austria
| | - Klaus R Liedl
- Institute of General, Inorganic and Theoretical Chemistry, and Center for Molecular Biosciences Innsbruck (CMBI) , University of Innsbruck , Innrain 80-82 , A-6020 Innsbruck , Austria
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8
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Consiglio G, Forte G. Molecular dynamics study of coil-to-globule transition in a thermo-responsive oligomer bound to various surfaces: hydrophilic surfaces stabilize the coil form. Phys Chem Chem Phys 2018; 20:29754-29763. [PMID: 30462107 DOI: 10.1039/c8cp05396k] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The structural and dynamical properties of 40-mer of thermo-responsive polymer PNIPAM covalently bound to different surfaces have been studied, at different temperatures, by means of molecular dynamics simulations. Evolution of the radius of gyration, Rg, of the polymer chain and radial distribution functions (RDFs) calculated for the carbon atoms of the PNIPAM backbone with water oxygens and for the hydrogen atom of the amide groups with water oxygens indicate that functionalized surfaces affect the coil-to-globule transition of PNIPAM, by means of electrostatic interactions, increasing the lower critical solution temperature (LCST) of the polymer. Such interactions, mainly represented by a H-bond, hinder the transition in the globular form while hydrophobic groups on the surface, such as -OCH3, contribute to the globular collapse. A significant alteration in the arrangement of water molecules around the polymer is testified by: (i) the absence of the second peak in the RDF between the C atoms of the PNIPAM backbone and the O atoms of water at the same temperature at which the radius of gyration decreases; (ii) the height of both the first and the second peak of the RDF between the H atom of the amide groups and water O atoms decreases when the temperature increases above the LCST. Finally, the H-bond autocorrelation function indicates that: (i) hydrogen bonds between the bound-to-surface PNIPAM acceptor groups (O[double bond, length as m-dash]C[double bond splayed right]) and the H atoms of water molecules are less persistent than H-bonds formed between the free PNIPAM acceptor groups and water; (ii) H-bonds between the PNIPAM acceptor groups and hydroxyl groups on the quartz surface are longer lived than those formed on graphene oxide.
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Affiliation(s)
- Giuseppe Consiglio
- Dipartimento di Scienze Chimiche, Università di Catania, I-95125 Catania, Italy.
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9
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Bejagam KK, An Y, Singh S, Deshmukh SA. Machine-Learning Enabled New Insights into the Coil-to-Globule Transition of Thermosensitive Polymers Using a Coarse-Grained Model. J Phys Chem Lett 2018; 9:6480-6488. [PMID: 30372083 DOI: 10.1021/acs.jpclett.8b02956] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We present a computational framework that integrates coarse-grained (CG) molecular dynamics (MD) simulations and a data-driven machine-learning (ML) method to gain insights into the conformations of polymers in solutions. We employ this framework to study conformational transition of a model thermosensitive polymer, poly( N-isopropylacrylamide) (PNIPAM). Here, we have developed the first of its kind, a temperature-independent CG model of PNIPAM that can accurately predict its experimental lower critical solution temperature (LCST) while retaining the tacticity in the presence of an explicit water model. The CG model was extensively validated by performing CG MD simulations with different initial conformations, varying the radius of gyration of chain, the chain length, and the angle between the adjacent monomers of the initial configuration of PNIPAM (total simulation time = 90 μs). Moreover, for the first time, we utilize the nonmetric multidimensional scaling (NMDS) method, a data-driven ML approach, to gain further insights into the mechanisms and pathways of this coil-to-globule transition by analyzing CG MD simulation trajectories. NMDS analysis provides entirely new insights and shows multiple metastable states of PNIPAM during its coil-to-globule transition above the LCST.
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Affiliation(s)
- Karteek K Bejagam
- Department of Chemical Engineering , Virginia Tech , Blacksburg , Virginia 24061 , United States
| | - Yaxin An
- Department of Chemical Engineering , Virginia Tech , Blacksburg , Virginia 24061 , United States
| | - Samrendra Singh
- CNH Industrial , Burr Ridge , Illinois 60527 , United States
| | - Sanket A Deshmukh
- Department of Chemical Engineering , Virginia Tech , Blacksburg , Virginia 24061 , United States
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10
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de Oliveira TE, Marques CM, Netz PA. Molecular dynamics study of the LCST transition in aqueous poly(N-n-propylacrylamide). Phys Chem Chem Phys 2018; 20:10100-10107. [PMID: 29589029 DOI: 10.1039/c8cp00481a] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The breadth of technological applications of smart polymers relies on the possibility of tuning their molecular structure to respond to external stimuli. In this context, N-substituted acrylamide-based polymers are widely studied thermoresponsive polymers. Poly(N-n-propylacrylamide) (PNnPAm), which is a structural isomer of the poly(N-isopropylacrylamide) (PNIPAm) exhibits however, a lower phase transition in aqueous solution. In this work, we use all-atom molecular dynamics simulations of PNnPAm in aqueous solutions to study, from a microscopic point-of-view, the influence of chain size and concentration on the LCST of PNnPAm. Our analysis shows that the collapse of a single oligomer of PNnPAm upon heating is dependent on the chain length and corresponds to a complex interplay between hydration and intermolecular interactions. Analysis of systems with multiple chains shows an aggregation of PNnPAm chains above the LCST.
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Affiliation(s)
- Tiago E de Oliveira
- Institut Charles Sadron, Université de Strasbourg, CNRS, Strasbourg, France.
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11
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Wu TY, Zrimsek AB, Bykov SV, Jakubek RS, Asher SA. Hydrophobic Collapse Initiates the Poly( N-isopropylacrylamide) Volume Phase Transition Reaction Coordinate. J Phys Chem B 2018; 122:3008-3014. [PMID: 29481081 DOI: 10.1021/acs.jpcb.8b00740] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The best-known examples of smart, responsive hydrogels derive from poly( N-isopropylacrylamide) (PNIPAM) cross-linked polymer networks. These hydrogels undergo volume phase transitions (VPTs) triggered by temperature, chemical, and/or environmental changes. PNIPAM hydrogels can undergo more than 50-fold volume changes within ∼1 μs intervals. Studies have tried to elucidate the molecular mechanism of these extraordinarily large responses. Nevertheless, the molecular reaction coordinates that drive the VPT remain unclear. Using visible nonresonance Raman temperature-jump spectroscopy, we determined the molecular ordering of this VPT. The PNIPAM hydrophobic isopropyl and methylene groups dehydrate with time constants of 109 ± 64 and 104 ± 44 ns, initiating the volume collapse of PNIPAM. The subsequent dehydration of the PNIPAM amide groups is significantly slower, as our group previously discovered (360 ± 85 ns). This determination of the ordering of the molecular reaction coordinate of the PNIPAM VPT enables the development of the next generation of super-responsive materials.
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Affiliation(s)
- Tsung-Yu Wu
- Department of Chemistry , University of Pittsburgh , Pittsburgh , Pennsylvania 15260 , United States
| | - Alyssa B Zrimsek
- Department of Chemistry , University of Pittsburgh , Pittsburgh , Pennsylvania 15260 , United States
| | - Sergei V Bykov
- Department of Chemistry , University of Pittsburgh , Pittsburgh , Pennsylvania 15260 , United States
| | - Ryan S Jakubek
- Department of Chemistry , University of Pittsburgh , Pittsburgh , Pennsylvania 15260 , United States
| | - Sanford A Asher
- Department of Chemistry , University of Pittsburgh , Pittsburgh , Pennsylvania 15260 , United States
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12
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Bejagam KK, Singh S, An Y, Berry C, Deshmukh SA. PSO-Assisted Development of New Transferable Coarse-Grained Water Models. J Phys Chem B 2018; 122:1958-1971. [DOI: 10.1021/acs.jpcb.7b10542] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Karteek K. Bejagam
- Department
of Chemical Engineering, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Samrendra Singh
- CNH Industrial, Burr Ridge, Chicago, Illinois 60527, United States
| | - Yaxin An
- Department
of Chemical Engineering, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Carter Berry
- Department
of Chemical Engineering, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Sanket A. Deshmukh
- Department
of Chemical Engineering, Virginia Tech, Blacksburg, Virginia 24061, United States
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13
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Bejagam KK, Singh S, Deshmukh SA. Development of non-bonded interaction parameters between graphene and water using particle swarm optimization. J Comput Chem 2017; 39:721-734. [PMID: 29266458 DOI: 10.1002/jcc.25141] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 11/15/2017] [Accepted: 11/27/2017] [Indexed: 01/21/2023]
Abstract
New Lennard-Jones parameters have been developed to describe the interactions between atomistic model of graphene, represented by REBO potential, and five commonly used all-atom water models, namely SPC, SPC/E, SPC/Fw, SPC/Fd, and TIP3P/Fs by employing particle swarm optimization (PSO) method. These new parameters were optimized to reproduce the macroscopic contact angle of water on a graphene sheet. The calculated line tension was in the order of 10-11 J/m for the droplets of all water models. Our molecular dynamics simulations indicate the preferential orientation of water molecules near graphene-water interface with one OH bond pointing toward the graphene surface. Detailed analysis of simulation trajectories reveals the presence of water molecules with ≤∼1, ∼2, and ∼4 hydrogen bonds at the surface of air-water interface, graphene-water interface, and bulk region of the water droplet, respectively. Presence of water molecules with ≤∼1 and ∼2 hydrogen bonds suggest the existence of water clusters of different sizes at these interfaces. The trends observed in the libration, bending, and stretching bands of the vibrational spectra are closely associated with these structural features of water. The inhomogeneity in hydrogen bond network of water at the air-water and graphene-water interface is manifested by broadening of the peaks in the libration band for water present at these interfaces. The stretching band for the molecules in water droplet shows a blue shift as compared to the pure bulk water, which conjecture the presence of weaker hydrogen bond network in a droplet. © 2017 Wiley Periodicals, Inc.
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Affiliation(s)
- Karteek K Bejagam
- Department of Chemical Engineering, Virginia Tech, Blacksburg, Virginia, 24061
| | - Samrendra Singh
- Case New Holland Industrial, 6900 Veterans Blvd, Burr Ridge, Illinois, 60527
| | - Sanket A Deshmukh
- Department of Chemical Engineering, Virginia Tech, Blacksburg, Virginia, 24061
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14
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Identifying trends in hydration behavior for modifications to the hydrophobicity of poly(n-isopropylacrylamide). J Mol Graph Model 2017; 78:168-175. [DOI: 10.1016/j.jmgm.2017.09.021] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2017] [Revised: 09/27/2017] [Accepted: 09/28/2017] [Indexed: 11/23/2022]
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15
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Zaibudeen A, Philip J. Multi-stimuli responsive nanofluid with easy-to-visualize structural color patterns. Colloids Surf A Physicochem Eng Asp 2017. [DOI: 10.1016/j.colsurfa.2017.01.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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16
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de Oliveira TE, Mukherji D, Kremer K, Netz PA. Effects of stereochemistry and copolymerization on the LCST of PNIPAm. J Chem Phys 2017; 146:034904. [DOI: 10.1063/1.4974165] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Tiago E. de Oliveira
- Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
- Max-Planck Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany
| | - Debashish Mukherji
- Max-Planck Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany
| | - Kurt Kremer
- Max-Planck Institut für Polymerforschung, Ackermannweg 10, 55128 Mainz, Germany
| | - Paulo A. Netz
- Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil
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17
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Deshmukh SA, Solomon LA, Kamath G, Fry HC, Sankaranarayanan SKRS. Water ordering controls the dynamic equilibrium of micelle-fibre formation in self-assembly of peptide amphiphiles. Nat Commun 2016; 7:12367. [PMID: 27554944 PMCID: PMC4999504 DOI: 10.1038/ncomms12367] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Accepted: 06/27/2016] [Indexed: 01/29/2023] Open
Abstract
Understanding the role of water in governing the kinetics of the self-assembly processes of amphiphilic peptides remains elusive. Here, we use a multistage atomistic-coarse-grained approach, complemented by circular dichroism/infrared spectroscopy and dynamic light scattering experiments to highlight the dual nature of water in driving the self-assembly of peptide amphiphiles (PAs). We show computationally that water cage formation and breakage near the hydrophobic groups control the fusion dynamics and aggregation of PAs in the micellar stage. Simulations also suggest that enhanced structural ordering of vicinal water near the hydrophilic amino acids shifts the equilibrium towards the fibre phase and stimulates structure and order during the PA assembly into nanofibres. Experiments validate our simulation findings; the measured infrared O–H bond stretching frequency is reminiscent of an ice-like bond which suggests that the solvated water becomes increasingly ordered with time in the assembled peptide network, thus shedding light on the role of water in a self-assembly process. The role of water in the kinetics of the self-assembly process of amphiphilic peptides still remains unknown. Sankaranarayanan et al. have shown through computational study that water has a dual nature when dictating the mechanism and dynamics of self-assembly of peptide amphiphiles.
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Affiliation(s)
- Sanket A Deshmukh
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Lee A Solomon
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Ganesh Kamath
- Department of Chemistry, University of Missouri-Columbia, Columbia, Missouri 65211, USA
| | - H Christopher Fry
- Center for Nanoscale Materials, Argonne National Laboratory, Lemont, Illinois 60439, USA
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18
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Wang XJ, Zhao XY, Li QG, Chan TW, Wu SZ. Artificial Neural Network Modeling and Mechanism Study for Relaxation of Deformed Rubber. Ind Eng Chem Res 2016. [DOI: 10.1021/acs.iecr.6b00010] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | | | | | - Tung W. Chan
- Department
of Materials Science and Engineering, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, United States
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The solvent quality of water for poly(N-isopropylacrylamide) in the collapsed state: Implications from single-molecule studies. CHINESE JOURNAL OF POLYMER SCIENCE 2016. [DOI: 10.1007/s10118-016-1773-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Min SH, Kwak SK, Kim BS. Atomistic simulation for coil-to-globule transition of poly(2-dimethylaminoethyl methacrylate). SOFT MATTER 2015; 11:2423-2433. [PMID: 25662300 DOI: 10.1039/c4sm02242d] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The coil-to-globule transition of poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) in aqueous solution was investigated by all-atomistic molecular dynamics simulations. The polymer consistent force field (PCFF) was applied to the PDMAEMA model with a proper protonation state. The structural analysis indicates a distinct difference in the hydration state of particular functional groups of PDMAEMA as well as in the conformational state of PDMAEMA below and above the lower critical solution temperature (LCST). In particular, by monitoring the motion of water molecules, we observe that water molecules in the vicinity of the carbonyl group are relatively restricted to the motion in the globule state due to the extended relaxation time of hydrogen bonds among water molecules. The degree of protonation was also adjusted to study the effect of protonation on the conformational state of PDMAEMA.
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Affiliation(s)
- Sa Hoon Min
- Department of Energy Engineering, School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology (UNIST), Ulsan 689-798, Korea
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Zhang H, Kim JC. Hydroxyethyl Acrylate-Based Polymeric Amphiphiles Showing Lower Critical Solution Temperature. JOURNAL OF MACROMOLECULAR SCIENCE PART A-PURE AND APPLIED CHEMISTRY 2015. [DOI: 10.1080/10601325.2015.980764] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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Deshmukh SA, Kamath G, Sankaranarayanan SKRS. Comparison of the interfacial dynamics of water sandwiched between static and free-standing fully flexible graphene sheets. SOFT MATTER 2014; 10:4067-4083. [PMID: 24845025 DOI: 10.1039/c3sm53044b] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Classical molecular dynamics simulations are used to present a detailed atomistic picture of the instantaneous local structures of water and the structural evolution of stationary and dynamically evolving graphene-water interfaces. The confinement effects are strongly coupled to the nature of the interface, which eventually governs its nanoscopic structural arrangements and interface dynamics. We show that the structure, transport properties, and vibrational densities of states of proximal water molecules are strongly correlated with the nature of the graphene-water interface. We identify and correlate features in vibrational spectra with characteristic structural features observed at the atomic scale for the confined water molecules near a stationary and dynamically evolving hydrophobic surface such as graphene. Our simulations indicate that the local orientation, ordering, and solvation dynamics of interfacial water molecules are a strong function of the graphene slit-width, which is controlled by the nature of the interface (fully flexible vs. static). A monotonic decrease in local ordering with increasing slit-width was observed for the static graphene-water interface, whereas a non-monotonic variation was seen for its fully flexible counterpart. The simulation results offer useful insights into the effect of interfacial dynamics in defining the structure and transport properties at graphene-aqueous media interfaces. Finally these simulations provide a molecular level interpretation of the differential confinement effects arising from the dynamically evolving graphene-water interface.
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Affiliation(s)
- Sanket A Deshmukh
- Argonne National Laboratory, Center for Nanoscale Materials, 9700 S. Cass Avenue, Argonne, IL 60439-4806, USA.
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Scherzinger C, Schwarz A, Bardow A, Leonhard K, Richtering W. Cononsolvency of poly-N-isopropyl acrylamide (PNIPAM): Microgels versus linear chains and macrogels. Curr Opin Colloid Interface Sci 2014. [DOI: 10.1016/j.cocis.2014.03.011] [Citation(s) in RCA: 112] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Deshmukh SA, Kamath G, Suthar KJ, Mancini DC, Sankaranarayanan SKRS. Non-equilibrium effects evidenced by vibrational spectra during the coil-to-globule transition in poly(N-isopropylacrylamide) subjected to an ultrafast heating-cooling cycle. SOFT MATTER 2014; 10:1462-1480. [PMID: 24651446 DOI: 10.1039/c3sm51750k] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Molecular dynamics simulations in conjunction with finite element calculations are used to explore the conformational dynamics of a thermo-sensitive oligomer, namely poly(N-isopropylacrylamide) (PNIPAM), subjected to an ultra-fast heating-cooling cycle. Finite element (FE) calculations were used to predict the temperature profile resulting from laser-induced heating of the polymer-aqueous system. The heating rate (∼0.6 K ps(-1)) deduced from FE calculations was used to heat an aqueous solution of PNIPAM consisting of 30 monomeric units (30-mer) from 285 K to 315 K. Non-equilibrium effects arising from the ultra-fast heating-cooling cycle results in a hysteresis during the coil-to-globule transition. The corresponding atomic scale conformations were characterized by monitoring the changes in the vibrational spectra, which provided a reliable metric to study the coil-to-globule transition in PNIPAM and vice-versa across the LCST. The vibrational spectra of bonds involving atoms from the oligomer backbone and the various side-groups (amide I, amide II, and the isopropyl group of PNIPAM) of the oligomers were analyzed to study the conformational changes in the oligomer corresponding to the observed hysteresis. The differences in the vibrational spectra calculated at various temperatures during heating and cooling cycles were used to understand the coil-to-globule and globule-to-coil transitions in the PNIPAM oligomer and identify the changes in the relative interactions between various atoms in the backbone and in the side groups of the oligomer with water. The shifts in the computed vibrational spectral peaks and the changes in the intensity of peaks for the different regions of PNIPAM, seen across the LCST during the heating cycle, are in good agreement with previous experimental studies. The changes in the radius of gyration (Rg) and vibrational spectra for amide I and amide II regions of PNIPAM suggest a clear coil-to-globule transition at ∼301 K during the heating cycle from 285 K to 315 K. During the heating cycle, a comparison of the vibrational spectra of isopropyl groups in PNIPAM at 285 K and 315 K suggests dehydration of the isopropyl moieties at 315 K. This implies that the oligomer-water interactions are dominant below the LCST whereas oligomer-oligomer interactions pre-dominate above the LCST. On the other hand, during the cooling cycle minor changes in the Rg and vibrational spectra of the PNIPAM oligomer in going from 315 K to 285 K indicate that the interactions between oligomer-oligomer and between the oligomer and water are less perturbed during the cooling cycle. Our simulations suggest that the observed hysteresis is a consequence of ultrafast heating-cooling kinetics, which allows insufficient relaxation times for the solvated oligomer.
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Affiliation(s)
- Sanket A Deshmukh
- Center for Nanoscale Materials, Argonne National Laboratory, Argonne, IL 60439, USA.
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Kamath G, Deshmukh SA, Baker GA, Mancini DC, Sankaranarayanan SKRS. Thermodynamic considerations for solubility and conformational transitions of poly-N-isopropyl-acrylamide. Phys Chem Chem Phys 2013; 15:12667-73. [DOI: 10.1039/c3cp44076a] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Atomistic insights into solvation dynamics and conformational transformation in thermo-sensitive and non-thermo-sensitive oligomers. POLYMER 2013. [DOI: 10.1016/j.polymer.2012.11.009] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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