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Liu YZ, Chen YN, Sun Q. The Dependence of Hydrophobic Interactions on the Shape of Solute Surface. Molecules 2024; 29:2601. [PMID: 38893477 PMCID: PMC11173737 DOI: 10.3390/molecules29112601] [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: 04/28/2024] [Revised: 05/26/2024] [Accepted: 05/29/2024] [Indexed: 06/21/2024] Open
Abstract
According to our recent studies on hydrophobicity, this work is aimed at understanding the dependence of hydrophobic interactions on the shape of a solute's surface. It has been observed that dissolved solutes primarily affect the structure of interfacial water, which refers to the top layer of water at the interface between the solute and water. As solutes aggregate in a solution, hydrophobic interactions become closely related to the transition of water molecules from the interfacial region to the bulk water. It is inferred that hydrophobic interactions may depend on the shape of the solute surface. To enhance the strength of hydrophobic interactions, the solutes tend to aggregate, thereby minimizing their surface area-to-volume ratio. This also suggests that hydrophobic interactions may exhibit directional characteristics. Moreover, this phenomenon can be supported by calculated potential mean forces (PMFs) using molecular dynamics (MD) simulations, where different surfaces, such as convex, flat, or concave, are associated with a sphere. Furthermore, this concept can be extended to comprehend the molecular packing parameter, commonly utilized in studying the self-assembly behavior of amphiphilic molecules in aqueous solutions.
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Affiliation(s)
| | | | - Qiang Sun
- Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, The School of Earth and Space Sciences, Peking University, Beijing 100871, China; (Y.-Z.L.); (Y.-N.C.)
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Chen YN, Liu YZ, Sun Q. The Molecular Mechanism of Ion Selectivity in Nanopores. Molecules 2024; 29:853. [PMID: 38398605 PMCID: PMC10891634 DOI: 10.3390/molecules29040853] [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: 11/09/2023] [Revised: 02/03/2024] [Accepted: 02/12/2024] [Indexed: 02/25/2024] Open
Abstract
Ion channels exhibit strong selectivity for specific ions over others under electrochemical potentials, such as KcsA for K+ over Na+. Based on the thermodynamic analysis, this study is focused on exploring the mechanism of ion selectivity in nanopores. It is well known that ions must lose part of their hydration layer to enter the channel. Therefore, the ion selectivity of a channel is due to the rearrangement of water molecules when entering the nanopore, which may be related to the hydrophobic interactions between ions and channels. In our recent works on hydrophobic interactions, with reference to the critical radius of solute (Rc), it was divided into initial and hydrophobic solvation processes. Additionally, the different dissolved behaviors of solutes in water are expected in various processes, such as dispersed and accumulated distributions in water. Correspondingly, as the ion approaches the nanopore, there seems to exist the "repulsive" or "attractive" forces between them. In the initial process (
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Affiliation(s)
| | | | - Qiang Sun
- Key Laboratory of Orogenic Belts and Crustal Evolution, The School of Earth and Space Sciences, Ministry of Education, Peking University, Beijing 100871, China; (Y.-N.C.); (Y.-Z.L.)
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Sun Q, He X, Fu Y. The "Beacon" Structural Model of Protein Folding: Application for Trp-Cage in Water. Molecules 2023; 28:5164. [PMID: 37446826 DOI: 10.3390/molecules28135164] [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: 05/30/2023] [Revised: 06/30/2023] [Accepted: 06/30/2023] [Indexed: 07/15/2023] Open
Abstract
Protein folding is a process in which a polypeptide must undergo folding process to obtain its three-dimensional structure. Thermodynamically, it is a process of enthalpy to overcome the loss of conformational entropy in folding. Folding is primarily related to hydrophobic interactions and intramolecular hydrogen bondings. During folding, hydrophobic interactions are regarded to be the driving forces, especially in the initial structural collapse of a protein. Additionally, folding is guided by the strong interactions within proteins, such as intramolecular hydrogen bondings related to the α-helices and β-sheets of proteins. Therefore, a protein is divided into the folding key (FK) regions related to intramolecular hydrogen bondings and the non-folding key (non-FK) regions. Various conformations are expected for FK and non-FK regions. Different from non-FK regions, it is necessary for FK regions to form the specific conformations in folding, which are regarded as the necessary folding pathways (or "beacons"). Additionally, sequential folding is expected for the FK regions, and the intermediate state is found during folding. They are reflected on the local basins in the free energy landscape (FEL) of folding. To demonstrate the structural model, molecular dynamics (MD) simulations are conducted on the folding pathway of the TRP-cage in water.
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Affiliation(s)
- Qiang Sun
- Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, The School of Earth and Space Sciences, Peking University, Beijing 100871, China
| | - Xian He
- Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, The School of Earth and Space Sciences, Peking University, Beijing 100871, China
| | - Yanfang Fu
- Key Laboratory of Orogenic Belts and Crustal Evolution, Ministry of Education, The School of Earth and Space Sciences, Peking University, Beijing 100871, China
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Karre AV, Valsaraj KT, Vasagar V. Review of air-water interface adsorption and reactions between trace gaseous organic and oxidant compounds. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 873:162367. [PMID: 36822420 DOI: 10.1016/j.scitotenv.2023.162367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2022] [Revised: 02/06/2023] [Accepted: 02/17/2023] [Indexed: 06/18/2023]
Abstract
The surface chemistry of the atmospheric aerosol through homogeneous and heterogeneous catalytic reactions in the bulk water and the air-water surface is reviewed. Water plays a critical role as a substrate or an actual reactant in atmospheric reactions. The atmospheric aerosol differs in shape and surface area. Many gaseous reactive species and oxidants react at the air-water surface. Different thermodynamic methods to estimate partitioning coefficients are explored. The Gibbs free energy is reduced when reactant gaseous species react with oxidant at the air-water surface; this phenomenon is explained using examples. Langmuir-Hinshelwood reaction mechanism to quantify the heterogeneous reaction rate at the air-water interface is discussed. Critical comparisons of various sampling techniques used to analyze adsorption and reaction at the water surface are presented. The heterogeneous reaction rate at the air-water surface is significantly higher than in the bulk water phase due to a cage effect, higher rate of reactions, and lower Gibbs free energy of adsorption.
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Affiliation(s)
| | - Kalliat T Valsaraj
- Cain Department of Chemical Engineering, Louisiana State University, LA 70803, United States
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Sun Q, Fu Y, Wang W. Temperature effects on hydrophobic interactions: Implications for protein unfolding. Chem Phys 2022. [DOI: 10.1016/j.chemphys.2022.111550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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Zheng J, Suwardi A, Wong CJE, Loh XJ, Li Z. Halogen bonding regulated functional nanomaterials. NANOSCALE ADVANCES 2021; 3:6342-6357. [PMID: 36133496 PMCID: PMC9419782 DOI: 10.1039/d1na00485a] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 09/22/2021] [Indexed: 06/16/2023]
Abstract
Non-covalent interactions have gained increasing attention for use as a driving force to fabricate various supramolecular architectures, exhibiting great potential in crystal and materials engineering and supramolecular chemistry. As one of the most powerful non-covalent bonds, the halogen bond has recently received increasing attention in functional nanomaterial design. The present review describes the latest studies based on halogen bonding induced self-assembly and its applications. Due to the high directionality and controllable interaction strength, halogen bonding can provide a facile platform for the design and synthesis of a myriad of nanomaterials. In addition, both the fundamental aspects and the real engineering applications are discussed, which encompass molecular recognition and sensing, organocatalysis, and controllable multifunctional materials and surfaces.
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Affiliation(s)
- Jie Zheng
- Institute of Materials Research and Engineering, ASTAR (Agency for Science, Technology and Research) Fusionopolis Way, Innovis, #08-03 Singapore 138634 Singapore
| | - Ady Suwardi
- Institute of Materials Research and Engineering, ASTAR (Agency for Science, Technology and Research) Fusionopolis Way, Innovis, #08-03 Singapore 138634 Singapore
| | - Claris Jie Ee Wong
- Department of Material Science and Engineering, National University of Singapore S117576 Singapore
| | - Xian Jun Loh
- Institute of Materials Research and Engineering, ASTAR (Agency for Science, Technology and Research) Fusionopolis Way, Innovis, #08-03 Singapore 138634 Singapore
| | - Zibiao Li
- Institute of Materials Research and Engineering, ASTAR (Agency for Science, Technology and Research) Fusionopolis Way, Innovis, #08-03 Singapore 138634 Singapore
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Sun Q, Wang W, Cui S. Directional nature of hydrophobic interactions: Implications for the mechanism of molecular recognition. Chem Phys 2021. [DOI: 10.1016/j.chemphys.2021.111200] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Williams T, Walsh C, Murray K, Subir M. Interactions of emerging contaminants with model colloidal microplastics, C 60 fullerene, and natural organic matter - effect of surface functional group and adsorbate properties. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2020; 22:1190-1200. [PMID: 32250376 DOI: 10.1039/d0em00026d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Surface adsorption of two commonly detected emerging contaminants, amlodipine (AMP) and carbamazepine (CBZ), onto model colloidal microplastics, natural organic matter (NOM), and fullerene nanomaterials have been investigated. It is found that AMP accumulation at these colloidal-aqueous interfaces is markedly higher than that of CBZ. Measurements of surface excess and particle zeta potential, along with pH-dependent adsorption studies, reveal a distinct influence of colloidal functional group on the adsorption properties of these pharmaceuticals. AMP shows a clear preference for a surface containing carboxylic group compared to an amine modified surface. CBZ, in contrast, exhibit a pH-dependent surface proclivity for both of these microparticles. The type of interactions and molecular differences with respect to structural rigidity and charge properties explain these observed behaviors. In this work, we also demonstrate a facile approach in fabricating uniform microspheres coated with NOM and C60 nanoclusters. Subsequent binding studies on these surfaces show considerable adsorption on the NOM surface but a minimal uptake of CBZ by C60. Adsorption induced colloidal aggregation was not observed. These findings map out the extent of contaminant removal by colloids of different surface properties available in the aquatic environment. The methodology developed for the adsorption study also opens up the possibility for further investigations into colloidal-contaminant interactions.
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Abstract
In this study, molecular dynamic simulations are employed to investigate the homogeneous nucleation mechanism of NaCl crystal in solutions. According to the simulations, the dissolved behaviors of NaCl in water are dependent on ion concentrations. With increasing NaCl concentrations, the dissolved Na+ and Cl- ions tend to be aggregated in solutions. In combination with our recent studies, the aggregate of dissolved solutes is mainly ascribed to the hydrophobic interactions. Different from the two-step mechanism, no barrier is needed to overcome the formation of the aggregate. In comparison with the classical nucleation theory (CNT), because of the formation of solute aggregate, this lowers the barrier height of nucleation and affects the nucleation mechanism of NaCl crystal in water.
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