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Investigations into the interaction thermodynamics of TRAP-related peptides with a temperature-responsive polymer-bonded porous silica stationary phase. Anal Chim Acta X 2019; 1:100008. [PMID: 33117975 PMCID: PMC7587034 DOI: 10.1016/j.acax.2019.100008] [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] [Indexed: 11/24/2022] Open
Abstract
The interaction thermodynamics of the thrombin receptor agonistic peptide (TRAP-1), H-Ser-Phe-Leu-Leu-Arg-Asn-Pro-OH, and a set of alanine scan substitution peptides, have been investigated with an n-octadecylacrylic polymer-bonded porous silica (Sil-ODA18) and water-acetonitrile mobile phases at temperatures ranging from 5 to 80 °C in 5 °C increments. The retention of these peptides on the Sil-ODA18 stationary phase decreased as the water content in the mobile phase was lowered from 80% (v/v) to ca. 45% (v/v) and reached a minimum value for each peptide at a specific water-acetonitrile composition. Further decreases in the water content of the mobile phase led to increased retention. The magnitude of the changes in enthalpy of interaction, Δ H a s s o c 0 , changes in entropy of interaction, Δ S a s s o c 0 , and changes in heat capacity, Δ C p 0 , were found to be dependent on the molecular properties of the mobile phase, the temperature, the structure/mobility of the stationary phase, and the conformation and solvation state of the peptides. With water-rich mobile phases, the retention behaviour of the TRAP analogues was dominated by enthalpic processes, consistent with the participation of strong hydrogen bonding effects, but became dominated by entropic effects with acetonitrile-rich mobile phases as the temperature was increased. These changes in the retention behaviour of these TRAP peptides are consistent with the generation of water or acetonitrile clusters in the mobile phase depending on the volume fractions of the organic solvent as the Sil-ODA18 stationary phase transitions from its crystalline to its isotropic state.
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Sepehrifar R, Boysen RI, Danylec B, Yang Y, Saito K, Hearn MT. Design, synthesis and application of a new class of stimuli-responsive separation materials. Anal Chim Acta 2017; 963:153-163. [DOI: 10.1016/j.aca.2017.01.061] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2016] [Revised: 01/25/2017] [Accepted: 01/29/2017] [Indexed: 11/29/2022]
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Kulsing C, Yang Y, Sepehrifar R, Lim M, Toppete J, Matyska MT, Pesek JJ, Boysen RI, Hearn MTW. Investigations into the separation behaviour of perfluorinated C8 and undecanoic acid modified silica hydride stationary phases. Anal Chim Acta 2016; 916:102-11. [PMID: 27016444 DOI: 10.1016/j.aca.2016.02.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Revised: 02/12/2016] [Accepted: 02/14/2016] [Indexed: 11/25/2022]
Abstract
In this study, the surface charge properties of perfluorinated C8 (PerfluoroC8) and undecanoic acid (UDA) modified silica hydride stationary phases have been investigated. The zeta potential values of these stationary phases were measured in aqueous/acetonitrile mobile phases of different pH, buffer concentrations and acetonitrile contents. The retention behaviour of several basic, acidic and neutral compounds were then examined with these two stationary phases, with U-shaped retention dependencies evident with regard to the organic solvent content of the mobile phase. Plots of the logarithmic retention factor versus buffer concentration revealed slopes ≥ -0.41 for both stationary phases, indicating the involvement of mixed mode retention mechanisms with contributions from both ionic and non-ionic interactions. Using a linear solvation energy relationship approach, the origins of these interactions under different mobile phase conditions were differentiated and quantified. The PerfluoroC8 stationary phase exhibited stronger retention for basic compounds under high acetonitrile content mobile phase conditions, whilst stronger retention was observed for all compounds with the UDA stationary phase under high aqueous content mobile phase conditions. The more negative zeta potentials of the UDA stationary phase correlated with higher total charge density, surface charge density and charge density at the beta plane (the outer plane of the double layer) compared to the PerfluoroC8 stationary phase. With mobile phases of low buffer concentrations, more negative zeta potential values were unexpectedly observed for the PerfluoroC8 stationary phase with slight increases in the C descriptor value, reflecting also the greater accessibility of the analytes to the stationary phase surface. Comparison of the retention behaviours on these phases with other types of silica hydride stationary phases has revealed different patterns of selectivity.
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Affiliation(s)
- Chadin Kulsing
- Australian Centre for Research on Separation Science (ACROSS), School of Chemistry, Monash University, Melbourne, Victoria 3800, Australia
| | - Yuanzhong Yang
- Australian Centre for Research on Separation Science (ACROSS), School of Chemistry, Monash University, Melbourne, Victoria 3800, Australia
| | - Roshanak Sepehrifar
- Australian Centre for Research on Separation Science (ACROSS), School of Chemistry, Monash University, Melbourne, Victoria 3800, Australia
| | - Michael Lim
- Department of Chemistry, San Jose State University, San Jose, CA 95192, USA
| | - Joshua Toppete
- Department of Chemistry, San Jose State University, San Jose, CA 95192, USA
| | - Maria T Matyska
- Department of Chemistry, San Jose State University, San Jose, CA 95192, USA
| | - Joseph J Pesek
- Department of Chemistry, San Jose State University, San Jose, CA 95192, USA
| | - Reinhard I Boysen
- Australian Centre for Research on Separation Science (ACROSS), School of Chemistry, Monash University, Melbourne, Victoria 3800, Australia
| | - Milton T W Hearn
- Australian Centre for Research on Separation Science (ACROSS), School of Chemistry, Monash University, Melbourne, Victoria 3800, Australia.
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Molecular orientation of gel forming compounds and their effect on molecular-shape selectivity in liquid chromatography. J Chromatogr A 2014; 1324:149-54. [DOI: 10.1016/j.chroma.2013.11.032] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Revised: 11/13/2013] [Accepted: 11/14/2013] [Indexed: 11/20/2022]
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Mallik AK, Qiu H, Sawada T, Takafuji M, Ihara H. Molecular shape recognition through self-assembled molecular ordering: evaluation with determining architecture and dynamics. Anal Chem 2012; 84:6577-85. [PMID: 22788678 DOI: 10.1021/ac300791x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The relationship between molecular gel-forming compound-based double-alkylated L-glutamide-derived functional group-integrated organic phase (Sil-FIP) structure and chromatographic performance is investigated and compared with widely used alkyl phases (C(30), polymeric and monomeric C(18)) as references. The functional group-integrated molecular gel on silica is chemically designed newly in a way that the weak interaction sites are integrated with high orientation and high selectivity can be realized by multiple interactions with the solutes. Its functions can be emphasized by being immobilizable with a terminal carboxyl group and the fact that five amide bonds including β-alanine subunit are integrated per molecule. Furthermore, its self-assembling function can be detected by monitoring of the chiroptical property. Temperature-dependent circular dichroism (CD) intensity was determined as an indicator of chirality for the gel forming compounds. (13)C cross-polarization magic angle spinning (CP/MAS) NMR spectra of the Sil-FIP phase indicate that predominance of gauche conformations exists at higher temperature (above 30 °C). (29)Si CP/MAS NMR were carried out to investigate the degree of cross-linking of the silane and silane functionality of the modified silica. Temperature-dependent (13)C CP/MAS NMR and suspended-state (1)H NMR measurements of the Sil-FIP phase exhibit the dynamic behavior of the alkyl chains. To correlate the NMR and CD results with temperature-dependent chromatographic studies, standard reference materials (SRM 869b and SRM 1647e), column selectivity test mixture for liquid chromatography was employed. Additional shape selectivity text mixtures were also used to clarify the mechanism of shape selectivity performance of Sil-FIP compared with commercially available columns. The evaluation with the spectroscopic and chromatographic analyses presents very important information on the surface morphology of the new organic phase and the molecular recognition process. Integrated and ordered functional groups were investigated to be the main driving force for very high molecular shape selectivity of the Sil-FIP phase.
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Affiliation(s)
- Abul K Mallik
- Department of Applied Chemistry and Biochemistry, Faculty of Engineering, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan
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Mallik AK, Qiu H, Sawada T, Takafuji M, Ihara H. Molecular-shape selectivity by molecular gel-forming compounds: bioactive and shape-constrained isomers through the integration and orientation of weak interaction sites. Chem Commun (Camb) 2011; 47:10341-3. [PMID: 21853211 DOI: 10.1039/c1cc13397g] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A molecular gel system was assembled on carrier particles and the integrated effect of weak interaction sites enabled highly efficient separation of the bioactive and shape-constrained isomers of tocopherols, β-carotene, and polycyclic aromatic hydrocarbons (PAHs) by multiple interaction mechanisms.
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Affiliation(s)
- Abul K Mallik
- Department of Applied Chemistry and Biochemistry, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan
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Qiu H, Mallik AK, Takafuji M, Ihara H. A Facile and Specific Approach to New Liquid Chromatography Adsorbents Obtained by Ionic Self‐Assembly. Chemistry 2011; 17:7288-97. [DOI: 10.1002/chem.201100137] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Indexed: 01/08/2023]
Affiliation(s)
- Hongdeng Qiu
- Department of Applied Chemistry and Biochemistry, Kumamoto University, 2‐39‐1 Kurokami, Kumamoto 860‐8555 (Japan), Fax: (+81) 96‐342‐3442
| | - Abul K. Mallik
- Department of Applied Chemistry and Biochemistry, Kumamoto University, 2‐39‐1 Kurokami, Kumamoto 860‐8555 (Japan), Fax: (+81) 96‐342‐3442
| | - Makoto Takafuji
- Department of Applied Chemistry and Biochemistry, Kumamoto University, 2‐39‐1 Kurokami, Kumamoto 860‐8555 (Japan), Fax: (+81) 96‐342‐3442
| | - Hirotaka Ihara
- Department of Applied Chemistry and Biochemistry, Kumamoto University, 2‐39‐1 Kurokami, Kumamoto 860‐8555 (Japan), Fax: (+81) 96‐342‐3442
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Nagrath D, Xia F, Cramer SM. Characterization and modeling of nonlinear hydrophobic interaction chromatographic systems. J Chromatogr A 2011; 1218:1219-26. [DOI: 10.1016/j.chroma.2010.12.111] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2010] [Revised: 12/24/2010] [Accepted: 12/31/2010] [Indexed: 11/16/2022]
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9
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Shundo A, Mallik AK, Nakashima H, Takafuji M, Nagaoka S, Chowdhury MAJ, Ihara H. Enhancement of Discrimination Ability for cis- and trans-Decalins through Side-chain Ordering in Comb-shaped Polymer. CHEM LETT 2010. [DOI: 10.1246/cl.2010.844] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Mallik AK, Sawada T, Takafuji M, Ihara H. Novel Approach for the Separation of Shape-Constrained Isomers with Alternating Copolymer-Grafted Silica in Reversed-Phase Liquid Chromatography. Anal Chem 2010; 82:3320-8. [DOI: 10.1021/ac1001178] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Abul K. Mallik
- Department of Applied Chemistry and Biochemistry, Faculty of Engineering, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan
| | - Tsuyoshi Sawada
- Department of Applied Chemistry and Biochemistry, Faculty of Engineering, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan
| | - Makoto Takafuji
- Department of Applied Chemistry and Biochemistry, Faculty of Engineering, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan
| | - Hirotaka Ihara
- Department of Applied Chemistry and Biochemistry, Faculty of Engineering, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan
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Nguyen Viet C, Trathnigg B. Determination of thermodynamic parameters in reversed phase chromatography for polyethylene glycols and their methyl ethers in different mobile phases. J Sep Sci 2010; 33:464-74. [DOI: 10.1002/jssc.200900638] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Ihara H, Takafuji M, Sakurai T, Tsukamoto H, Shundo A, Sagawa T, Nagaoka S. Facile Enantiomer Analysis by Combination of N‐Dansyl Amino Acid as Diastereomerizer and Molecular‐Shape Recognitive RP‐HPLC Using Comb‐Shaped Polymer‐Immobilized Silica. J LIQ CHROMATOGR R T 2009. [DOI: 10.1081/jlc-200028400] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
- H. Ihara
- a Institute for Materials Chemistry and Engineering , Kyushu University , Fukuoka , Japan
- b Department of Applied Chemistry , Kumamoto University , Kumamoto , Japan
| | - M. Takafuji
- b Department of Applied Chemistry , Kumamoto University , Kumamoto , Japan
| | - T. Sakurai
- b Department of Applied Chemistry , Kumamoto University , Kumamoto , Japan
| | - H. Tsukamoto
- b Department of Applied Chemistry , Kumamoto University , Kumamoto , Japan
| | - A. Shundo
- b Department of Applied Chemistry , Kumamoto University , Kumamoto , Japan
| | - T. Sagawa
- c Institute of Advanced Energy , Kyoto University , Uji , Japan
| | - S. Nagaoka
- d Kumamoto Industrial Research Institute , Kumamoto , Japan
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Mallik AK, Takafuji M, Ihara H. Tuning of the molecular packing structure of comb-shaped polymer-grafted silica by using surface-initiated ATRP to enhance the molecular-shape selectivity towards polycyclic aromatic hydrocarbons. Eur Polym J 2009. [DOI: 10.1016/j.eurpolymj.2009.02.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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14
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Synthesis and assessment of molecular recognizability by RP-HPLC of an N-alkyl-β-Ala-L-Phe-derived organic phase with self-assembling ability. Anal Bioanal Chem 2008; 392:1197-208. [DOI: 10.1007/s00216-008-2368-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2008] [Revised: 08/19/2008] [Accepted: 08/21/2008] [Indexed: 10/21/2022]
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Rahman MM, Takafuji M, Ihara H. Evaluation of selectivity for L-glutamide-derived highly ordered assemblies in reversed-phase high-performance liquid chromatography. Talanta 2008; 77:1228-37. [PMID: 19064117 DOI: 10.1016/j.talanta.2008.08.028] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2008] [Revised: 08/23/2008] [Accepted: 08/26/2008] [Indexed: 11/16/2022]
Abstract
Two dioctadecyl L-glutamic acid derivatives with amide and ester type bondings have been synthesized and immobilized from 3-aminopropyltrimethoxysilane (APS) grafted silica (Sil-APS) to be used in reversed-phase high-performance liquid chromatography (RP-HPLC). Subsequent studies showed that dioctadecyl-L-glutamide derivative (GLN) can self-assemble into highly ordered structures by forming three-dimensional fibrillar aggregates as observed in scanning and transmission electron microscopes (SEM and TEM). Variable temperature (1)H NMR and FT-IR spectra of organogel revealed that the special aggregation morphology shown by GLN was stabilized by inter and or intra molecular hydrogen bonding among amide moieties. However, such ordered aggregated or self-assembled structures were not observed for the dioctadecyl-L-glutamate (GLU) derivative. The stationary phases Sil-GLN and Sil-GLU were characterized by DRIFT, elemental analysis, TGA, and (13)C and (29)Si CP-MAS NMR spectroscopic measurements. The chromatographic selectivity for both stationary phases was evaluated from the retention studies of different size and shape polycyclic aromatic hydrocarbons (PAHs). The chromatographic experiment for PAHs and geometrical isomers in RP-HPLC showed that Sil-GLN demonstrated extremely enhanced selectivity than Sil-GLU. The higher selectivity attributed by Sil-GLN has been brought by multiple pi-pi interactions among the pi-electrons of the grafted organic phase and pi-electrons of the guest PAHs molecules. Thermodynamic studies for linear and nonlinear PAHs revealed that the retention behavior does not change over a temperature range from 10 to 60 degrees C for both stationary phases.
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Affiliation(s)
- M Mizanur Rahman
- Department of Applied Chemistry and Biochemistry, Faculty of Engineering, Kumamoto University, Kumamoto, Japan.
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Rahman MM, Takafuji M, Ihara H. Preparation, telomerization, immobilization and application of N-alkyl l-phenylalanine-derived polymerizable organogelator for reversed-phase high-performance liquid chromatography. J Chromatogr A 2008; 1203:59-66. [DOI: 10.1016/j.chroma.2008.07.022] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2008] [Revised: 07/02/2008] [Accepted: 07/08/2008] [Indexed: 10/21/2022]
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Mallik AK, Rahman MM, Czaun M, Takafuji M, Ihara H. Facile synthesis of high-density poly(octadecyl acrylate)-grafted silica for reversed-phase high-performance liquid chromatography by surface-initiated atom transfer radical polymerization. J Chromatogr A 2008; 1187:119-27. [DOI: 10.1016/j.chroma.2008.02.011] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2007] [Revised: 01/28/2008] [Accepted: 02/05/2008] [Indexed: 10/22/2022]
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Chen J, Cramer SM. Protein adsorption isotherm behavior in hydrophobic interaction chromatography. J Chromatogr A 2007; 1165:67-77. [PMID: 17698076 DOI: 10.1016/j.chroma.2007.07.038] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2007] [Revised: 07/18/2007] [Accepted: 07/20/2007] [Indexed: 10/23/2022]
Abstract
The adsorption behavior of proteins in hydrophobic interaction chromatography (HIC) was evaluated by determining the isotherms of a wide range of proteins on various HIC resin systems. Parallel batch experiments were carried out with eleven proteins on three hydrophobic resins with different ligand chemistries and densities. The effects of salt concentration, resin chemistry and protein properties on the isotherms were also examined. The resulting isotherms exhibited unique patterns of adsorption behaviors. For certain protein-resin combinations, a "critical salt behavior" was observed where the amount of protein bound to the resin increased significantly above this salt concentration. Proteins that exhibited this behavior tended to be relatively large with more solvent accessible hydrophobic surface area. Further, calculations indicated that under these conditions the occupied surface area of the adsorbed protein layer could exceed the accessible surface area. The establishment of unique classes of adsorption behavior may shed light on our understanding of the behavior of proteins in HIC systems.
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Affiliation(s)
- Jie Chen
- Department of Chemical and Biological Engineering, RPI, NY 12180, USA.
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Rahman MM, Takafuji M, Ansarian HR, Ihara H. Molecular shape selectivity through multiple carbonyl-pi interactions with noncrystalline solid phase for RP-HPLC. Anal Chem 2006; 77:6671-81. [PMID: 16223255 DOI: 10.1021/ac050851v] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A new approach for the synthesis of double-alkylated L-glutamide-derived stationary phases to use in RP-HPLC is described. TEM observation of lipid distearylglutamide (DSG) showed the formation of fibrous aggregates in methanol or in chloroform through intermolecular hydrogen bonding among the amide moieties while dibutylglutamide (DBG) cannot aggregate in aqueous or organic media due to its lower order of short alkyl chain. DSG and DBG were covalently bonded to silica via amino-propyl linkages. Lipid membrane analogues (e.g., DSG) attached to the silica surface have been found in noncrystalline and solid states and can form supramolecular assemblies with specific properties based on their highly ordered structures in aqueous and organic media. 13C CP/MAS NMR and suspension (in methanol)-state 1H NMR, elemental analysis, and DSC measurements were used to characterize Sil-DSG and were compared with the three other octadecyl phases, i.e., monomeric C18, polymeric C18, and silica grafted poly(octadecyl acrylate) Sil-ODA25. The chromatographic behavior of the new RP material was investigated using detailed retention studies of planar and nonplanar polyaromatic hydrocarbons (PAHs) and nonpolar aromatic positional isomers. Aspects of shape selectivity were also evaluated with Standard Reference Materials 869a, Column Selectivity Test Mixture for Liquid Chromatography. Detailed chromatographic study revealed that Sil-DSG showed extremely enhanced molecular shape selectivity compared with the other phases investigated. The higher molecular shape selectivity obtained by Sil-DSG can be explained by a carbonyl pi (present in lipid-grafted stationary phases)-benzene pi (present in guest PAHs) interaction mechanism, and these interactions are more effective for ordered carbonyl groups.
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Affiliation(s)
- M Mizanur Rahman
- Department of Applied Chemistry and Biochemistry, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan
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Derakhshan M, Ansarian HR, Rahman MM, Sakurai T, Takafuji M, Ihara H. A new method for evaluation of the mobility of silica-grafted alkyl chains by suspension-state 1H NMR. CAN J CHEM 2005. [DOI: 10.1139/v05-197] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although molecular mobility is usually probed by measurement of the T1 relaxation time, it is not the case for methylene groups of grafted acyl chains because each methylene group has a different mobility and hence, a different T1 relaxation time depending on the distance from the junction between organic molecule and nonorganic particle. Therefore, we devised a very simple method that can semiquantitatively determine the extent of mobility in the grafted acyl chains. Silica-supported poly(octadecylacrylate) (Sil-ODAn), polymeric octadecylsilyl silica (polymeric ODS), and monomeric octadecylsilyl silica (monomeric ODS) were studied by comparing the intensity of NMR peaks from grafted molecules with the same amount of nongrafted molecules. In the case of Sil-ODAn, with a gradual increase in temperature, the intensity of the proton signals (1H NMR) of the octadecyl moieties (mainly methylene groups) rose dramatically. This dramatic rise was at the same temperature as that of an endothermic peak detectable in its DSC thermogram, indicating a relatively complete solid to liquid phase transition. Sil-ODAn, as the stationary phase in RP-HPLC, showed analogous temperature dependencies of the separation factor between naphthacene and triphenylene (as a simple indicator of shape selectivity). Using this method we determined the liquid phase percentage (LPP) in Sil-ODAn, polymeric ODS, and monomeric ODS at various temperatures. We suggest LPP as a semiquantitative index of mobility for grafted organic layers.Key words: comb-shaped polymer, nanocomposite, alkyl chain mobility, NMR, liquid chromatography.
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Takafuji M, Rahman MM, Ansarian HR, Derakhshan M, Sakurai T, Ihara H. Dioctadecyl L-glutamide-derived lipid-grafted silica as a novel organic stationary phase for RP-HPLC. J Chromatogr A 2005; 1074:223-8. [PMID: 15941059 DOI: 10.1016/j.chroma.2005.03.090] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Dialkyl L-glutamide-derived lipids have been found to form supramolecular assemblies and to show specific properties based on their highly ordered structures in aqueous and organic media. To use these unique properties to create molecular recognition systems, dioctadecyl L-glutamide-derived lipid-grafted porous silica particles (Sil-DSG) were newly prepared and used as a stationary phase in reversed phase liquid chromatography. Compared with conventional ODS (octadecylated silica), the Sil-DSG column showed remarkably higher selectivity for polycyclic aromatic hydrocarbons (PAHs). Especially, Sil-DSG recognized the molecular linearity and planarity of PAHs. Suspension state 1H NMR and 13C CP/MAS-NMR spectroscopies showed that the alkyl chains on the Sil-DSG are in gauche form and their mobility is strongly restricted at room temperature. This paper discusses higher selectivity of Sil-DSG with a carbonyl pi-benzene pi interactions.
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Affiliation(s)
- Makoto Takafuji
- Department of Applied Chemistry and Biochemistry, Kumamoto University, 2-39-1 Kurokami, Kumamoto, Japan
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Evaluation of microstructural features of a new polymeric organic stationary phase grafted on silica surface: A paradigm of characterization of HPLC-stationary phases by a combination of suspension-state 1H NMR and solid-state 13C-CP/MAS-NMR. Anal Chim Acta 2005. [DOI: 10.1016/j.aca.2005.05.052] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Ihara H, Fukui M, Mimaki T, Shundo A, Dong W, Derakhshan M, Sakurai T, Takafuji M, Nagaoka S. Poly(4-vinylpyridine) as a reagent with silanol-masking effect for silica and its specific selectivity for PAHs and dinitropyrenes in a reversed phase. Anal Chim Acta 2005. [DOI: 10.1016/j.aca.2005.05.056] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Takafuji M, Fukui M, Ansarian HR, Derakhshan M, Shundo A, Ihara H. Conformational Effect of Silica-supported Poly(octadecyl acrylate) on Molecular-Shape Selectivity of Polycyclic Aromatic Hydrocarbons in RP-HPLC. ANAL SCI 2004; 20:1681-5. [PMID: 15636515 DOI: 10.2116/analsci.20.1681] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Poly(octadecyl acrylate) with a terminal reactive group was synthesized by radical telomerization in various solvents. The polymers were grafted onto porous silica for use in RP-HPLC, and the molecular recognition ability was investigated along with the selectivity for the structural isomers of polycyclic aromatic hydrocarbons. The mechanism of selectivity was also investigated with differential scanning calorimetry and NMR spectroscopic observations.
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Affiliation(s)
- Makoto Takafuji
- Department of Applied Chemistry & Biochemistry, Kumamoto University, 2-39-1 Kurokami, Kumamoto 860-8555, Japan
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Hennessy TP, Boysen RI, Huber MI, Unger KK, Hearn MTW. Peptide mapping by reversed-phase high-performance liquid chromatography employing silica rod monoliths. J Chromatogr A 2003; 1009:15-28. [PMID: 13677642 DOI: 10.1016/s0021-9673(03)00445-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
In this paper, a general procedure is described for the generation of peptide maps of proteins with monolithic silica-based columns. The peptide fragments were obtained by tryptic digestion of various cytochrome c species with purification of the tryptic fragments achieved by reversed-phase high-performance liquid chromatographic methods. Peak assignment of the various peptides was based on evaluation of the biophysical properties of the individual peptides and via mass spectrometric identification. The performance of several different monolithic sorbents prepared as columns of identical cross-sectional dimensions were investigated as part of these peptide mapping studies and the data evaluated by applying solvent strength theory. These studies revealed curvilinear dependencies in the corresponding relative resolution maps. These findings directly impact on the selection of specific sorbent types or column configurations for peptide separations with silica rod monoliths. Moreover, the influence of variations in the amino acid sequence of the cytochrome cs were evaluated with respect to their effect on intrinsic hydrophobicity, the number of experimental observed tryptic cleavage sites, detection limits of the derived fragments in relation to their molecular size, and the chromatographic selectivity and resolution of the various peptides obtained following enzymatic fragmentation of the parent protein. Finally, the scope of these approaches in method development was examined in terms of robustness and efficiency.
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Affiliation(s)
- Tom P Hennessy
- Australian Research Council Special Research Centre for Green Chemistry, Centre for Bioprocess Technology, Australian Centre for Research on Separation Science, Monash University, PO Box 23, Clayton, Victoria 3800, Australia
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