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Lukiev IV, Mogelnitskaya YA, Mikhailov IV, Darinskii AA. Chains Stiffness Effect on the Vertical Segregation of Mixed Polymer Brushes in Selective Solvent. Polymers (Basel) 2023; 15:polym15030644. [PMID: 36771945 PMCID: PMC9919982 DOI: 10.3390/polym15030644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Revised: 01/15/2023] [Accepted: 01/24/2023] [Indexed: 01/28/2023] Open
Abstract
The microstructure of the binary polymer brushes in the selective solvent was studied using the numerical lattice self-consisting field approach. The case was considered when the selectivity to the solvent (the Flory-Huggins parameter χ) was varied only for one type of chains (responsive chains) while the others (non-responsive chains) remained hydrophilic (χ = 0). In such a brush, with an increase in the hydrophobicity of the responsive chains, a transition occurs between two two-layer microstructures. In the initial state the ends of the longer responsive chains are located near the external surface of the brush and those of non-responsive chains are inside the brush. When the hydrophobicity of the responsive chains becomes high enough then the reversed two-layer microstructure is formed, when the ends of non-responsive chains are located near the brush surface and the responsive chains collapse on the brush bottom. In contrast to previous works, the stiffness parameter (Kuhn segment length p) for one or for both types of chains was varied and its effect on the mechanism and characteristics of the transition was studied. If the stiffness of only responsive chains increases, then the transition occurs with the formation of an intermediate three-layer microstructure, where a layer of responsive chains is located between layers formed by non-responsive ones. If both types of chains have the same p, then the transition occurs gradually without the formation of an intermediate three-layer microstructure. For both cases, the effect of p on the critical value of χ*, corresponding to the transition point and on the steepness of the transition was investigated.
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Affiliation(s)
- Ivan V. Lukiev
- Center for Chemical Engineering, ITMO University, 197101 St. Petersburg, Russia
| | | | - Ivan V. Mikhailov
- Institute of Macromolecular Compounds, Russian Academy of Sciences, 199004 St. Petersburg, Russia
| | - Anatoly A. Darinskii
- Institute of Macromolecular Compounds, Russian Academy of Sciences, 199004 St. Petersburg, Russia
- Correspondence: ; Tel.: +7-911-280-9517
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Tolmachev D, Mamistvalov G, Lukasheva N, Larin S, Karttunen M. Effects of Amino Acid Side-Chain Length and Chemical Structure on Anionic Polyglutamic and Polyaspartic Acid Cellulose-Based Polyelectrolyte Brushes. Polymers (Basel) 2021; 13:polym13111789. [PMID: 34071693 PMCID: PMC8199235 DOI: 10.3390/polym13111789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Revised: 05/25/2021] [Accepted: 05/25/2021] [Indexed: 11/25/2022] Open
Abstract
We used atomistic molecular dynamics (MD) simulations to study polyelectrolyte brushes based on anionic α,L-glutamic acid and α,L-aspartic acid grafted on cellulose in the presence of divalent CaCl2 salt at different concentrations. The motivation is to search for ways to control properties such as sorption capacity and the structural response of the brush to multivalent salts. For this detailed understanding of the role of side-chain length, the chemical structure and their interplay are required. It was found that in the case of glutamic acid oligomers, the longer side chains facilitate attractive interactions with the cellulose surface, which forces the grafted chains to lie down on the surface. The additional methylene group in the side chain enables side-chain rotation, enhancing this effect. On the other hand, the shorter and more restricted side chains of aspartic acid oligomers prevent attractive interactions to a large degree and push the grafted chains away from the surface. The difference in side-chain length also leads to differences in other properties of the brush in divalent salt solutions. At a low grafting density, the longer side chains of glutamic acid allow the adsorbed cations to be spatially distributed inside the brush resulting in a charge inversion. With an increase in grafting density, the difference in the total charge of the aspartic and glutamine brushes disappears, but new structural features appear. The longer sides allow for ion bridging between the grafted chains and the cellulose surface without a significant change in main-chain conformation. This leads to the brush structure being less sensitive to changes in salt concentration.
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Affiliation(s)
- Dmitry Tolmachev
- Institute of Macromolecular Compounds, Russian Academy of Sciences, Bolshoy pr. 31, 199004 Petersburg, Russia; (N.L.); (S.L.)
- Correspondence: (D.T.); (M.K.)
| | - George Mamistvalov
- Faculty of Physics, St. Petersburg State University, Petrodvorets, 198504 Petersburg, Russia;
| | - Natalia Lukasheva
- Institute of Macromolecular Compounds, Russian Academy of Sciences, Bolshoy pr. 31, 199004 Petersburg, Russia; (N.L.); (S.L.)
| | - Sergey Larin
- Institute of Macromolecular Compounds, Russian Academy of Sciences, Bolshoy pr. 31, 199004 Petersburg, Russia; (N.L.); (S.L.)
- Faculty of Physics, St. Petersburg State University, Petrodvorets, 198504 Petersburg, Russia;
| | - Mikko Karttunen
- Institute of Macromolecular Compounds, Russian Academy of Sciences, Bolshoy pr. 31, 199004 Petersburg, Russia; (N.L.); (S.L.)
- Department of Chemistry, The University of Western Ontario, 1151 Richmond Street, London, ON N6A 5B7, Canada
- Department of Applied Mathematics, The University of Western Ontario, 1151 Richmond Street, London, ON N6A 5B7, Canada
- The Centre of Advanced Materials and Biomaterials Research, The University of Western Ontario, 1151 Richmond Street, London, ON N6A 5B7, Canada
- Correspondence: (D.T.); (M.K.)
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da Silva CNS, Di-Medeiros MCB, Lião LM, Fernandes KF, Batista KDA. Cashew Gum Polysaccharide Nanoparticles Grafted with Polypropylene Glycol as Carriers for Diclofenac Sodium. MATERIALS (BASEL, SWITZERLAND) 2021; 14:2115. [PMID: 33922015 PMCID: PMC8122507 DOI: 10.3390/ma14092115] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 04/07/2021] [Accepted: 04/20/2021] [Indexed: 12/11/2022]
Abstract
This investigation focuses on the development and optimization of cashew gum polysaccharide (CGP) nanoparticles grafted with polypropylene glycol (PPG) as carriers for diclofenac sodium. The optimization of parameters affecting nanoparticles formulation was performed using a central composite rotatable design (CCRD). It was demonstrated that the best formulation was achieved when 10 mg of CGP was mixed with 10 μL of PPG and homogenized at 22,000 rpm for 15 min. The physicochemical characterization evidenced that diclofenac was efficiently entrapped, as increases in the thermal stability of the drug were observed. The CGP-PPG@diclofenac nanoparticles showed a globular shape, with smooth surfaces, a hydrodynamic diameter around 275 nm, a polydispersity index (PDI) of 0.342, and a zeta potential of -5.98 mV. The kinetic studies evidenced that diclofenac release followed an anomalous transport mechanism, with a sustained release up to 68 h. These results indicated that CGP-PPG nanoparticles are an effective material for the loading/release of drugs with similar structures to diclofenac sodium.
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Affiliation(s)
- Cassio Nazareno Silva da Silva
- Laboratório de Química de Polímeros, Instituto de Ciências Biológicas, ICB2, Campus Samambaia, Universidade Federal de Goiás, Goiânia 74690-900, GO, Brazil; (C.N.S.d.S.); (K.F.F.)
| | | | - Luciano Morais Lião
- Laboratório de Ressonância Nuclear Magnética, Campus Samambaia, Universidade Federal de Goiás, Goiânia 74690-900, GO, Brazil;
| | - Kátia Flávia Fernandes
- Laboratório de Química de Polímeros, Instituto de Ciências Biológicas, ICB2, Campus Samambaia, Universidade Federal de Goiás, Goiânia 74690-900, GO, Brazil; (C.N.S.d.S.); (K.F.F.)
| | - Karla de Aleluia Batista
- Laboratório de Química de Polímeros, Instituto de Ciências Biológicas, ICB2, Campus Samambaia, Universidade Federal de Goiás, Goiânia 74690-900, GO, Brazil; (C.N.S.d.S.); (K.F.F.)
- Departamento de Áreas Acadêmicas, Instituto Federal de Educação, Ciência e Tecnologia de Goiás, Campus Goiânia Oeste, Goiânia 74270-040, GO, Brazil
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