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Le-McClain A, Zanelotti C, Robert H, Casanova F. Analysis of complex mixtures with benchtop nuclear magnetic resonance: Solvent suppression with T 2 and diffusion filters. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2024; 62:497-504. [PMID: 38369688 DOI: 10.1002/mrc.5438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 01/22/2024] [Accepted: 01/24/2024] [Indexed: 02/20/2024]
Abstract
Benchtop nuclear magnetic resonance (NMR) spectrometers are being employed in a wide variety of applications from undergraduate teaching and research in academia to quality control and process monitoring in industrial settings. Incorporating benchtop NMR in some of these applications presents opportunities for new practical uses of the technology and challenges that truly test the capabilities of compact NMR spectrometers. For instance, the use of protonated solvents in manufacturing or process monitoring requires separating and quantitating the analyte signals of interest from the strong (overwhelming) response from the solvents. Furthermore, due to the lower field strength available with permanent magnet spectrometers, the NMR spectra of complex mixtures can be more difficult to analyze due to partial or complete signal overlap. To address some of these challenges and to extend the range of applications of benchtop NMR, we investigate NMR techniques that enable quantitative analysis of different components in mixtures. These pulse sequences can be used to suppress one or multiple solvent peaks, to filter out signals by spin-spin relaxation time (T2), or to separate signal components by a molecule's diffusion coefficient (NMR diffusometry). In this paper, we discuss quantitative analysis of excipients in buffers for therapeutic proteins to highlight the usefulness of these NMR pulse sequences in the analysis of complex samples with benchtop NMR spectrometers.
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Li S, Cui R, Yu C, Zhou Y. Coarse-Grained Model of Thiol-Epoxy-Based Alternating Copolymers in Explicit Solvents. J Phys Chem B 2022; 126:1830-1841. [PMID: 35179028 DOI: 10.1021/acs.jpcb.1c09406] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The cosolvent method has been widely used in the self-assembly of amphiphilic alternating copolymers (ACPs), but the role of good and selective solvents is rarely investigated. Here, we have developed a coarse-grained (CG) model for the widely studied thiol-epoxy-based amphiphilic ACPs and a three-bead CG model for tetrahydrofuran (THF) as the good solvent, which is compatible with the MARTINI water model. The accuracy of both the CG polymer and THF models was validated by reproducing the structural and thermodynamic properties obtained from experiments or atomistic simulation results. Density in bulk, the radius of gyration, and solvation free energy in water or THF showed a good agreement between CG and atomistic models. The CG models were further employed to explore the self-assembly of ACPs in THF/water mixtures with different compositions. Chain folding and liquid-liquid phase separation behaviors were found with increasing water fractions, which were the key steps of the self-assembly process. This work will provide a basic platform to explore the self-assembly of amphiphilic ACPs in solvent mixtures and to reveal the real role of different solvents in self-assembly.
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Affiliation(s)
- Shanlong Li
- School of Chemistry & Chemical Engineering, Frontiers Science Center for Transformative Molecules, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Rui Cui
- School of Chemistry & Chemical Engineering, Frontiers Science Center for Transformative Molecules, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Chunyang Yu
- School of Chemistry & Chemical Engineering, Frontiers Science Center for Transformative Molecules, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Yongfeng Zhou
- School of Chemistry & Chemical Engineering, Frontiers Science Center for Transformative Molecules, Shanghai Jiao Tong University, Shanghai 200240, China
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Faisal KS, Clulow AJ, Krasowska M, Gillam T, Miklavcic SJ, Williamson NH, Blencowe A. Interrogating the relationship between the microstructure of amphiphilic poly(ethylene glycol-b-caprolactone) copolymers and their colloidal assemblies using non-interfering techniques. J Colloid Interface Sci 2022; 606:1140-1152. [PMID: 34492457 DOI: 10.1016/j.jcis.2021.08.084] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Revised: 07/20/2021] [Accepted: 08/10/2021] [Indexed: 10/20/2022]
Abstract
Understanding the microstructural parameters of amphiphilic copolymers that control the formation and structure of aggregated colloids (e.g., micelles) is essential for the rational design of hierarchically structured systems for applications in nanomedicine, personal care and food formulations. Although many analytical techniques have been employed to study such systems, in this investigation we adopted an integrated approach using non-interfering techniques - diffusion nuclear magnetic resonance (NMR) spectroscopy, dynamic light scattering (DLS) and synchrotron small-angle X-ray scattering (SAXS) - to probe the relationship between the microstructure of poly(ethylene glycol-b-caprolactone) (PEG-b-PCL) copolymers [e.g., block molecular weight (MW) and the mass fraction of PCL (fPCL)] and the structure of their aggregates. Systematic trends in the self-assembly behaviour were determined using a large family of well-defined block copolymers with variable PEG and PCL block lengths (number-average molecular weights (Mn) between 2 and 10 and 0.5-15 kDa, respectively) and narrow dispersity (Ð < 1.12). For all of the copolymers, a clear transition in the aggregate structure was observed when the hydrophobic fPCL was increased at a constant PEG block Mn, although the nature of this transition is also dependent on the PEG block Mn. Copolymers with low Mn PEG blocks (2 kDa) were observed to transition from unimers and loosely associated unimers to metastable aggregates and finally, to cylindrical micelles as the fPCL was increased. In comparison, copolymers with PEG block Mn of between 5 and 10 kDa transitioned from heterogenous metastable aggregates to cylindrical micelles and finally, well-defined ellipsoidal micelles (of decreasing aspect ratios) as the fPCL was increased. In all cases, the diffusion NMR spectroscopy, DLS and synchrotron SAXS results provided complementary information and the grounds for a phase diagram relating copolymer microstructure to aggregation behaviour and structure. Importantly, the absence of commonly depicted spherical micelles has implications for applications where properties may be governed by shape, such as, cellular uptake of nanomedicine formulations.
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Affiliation(s)
- Khandokar Sadique Faisal
- Applied Chemistry and Translational Biomaterials (ACTB) Group, UniSA CHS, University of South Australia, Adelaide, South Australia 5000, Australia
| | - Andrew J Clulow
- Drug Delivery, Disposition & Dynamics, Monash Institute of Pharmaceutical Sciences, 381 Royal Parade, Parkville, Victoria 3052, Australia
| | - Marta Krasowska
- Surface Interactions and Soft Matter (SISM) Group, Future Industries Institute, UniSA STEM, University of South Australia, Mawson Lakes, South Australia 5095, Australia
| | - Todd Gillam
- Applied Chemistry and Translational Biomaterials (ACTB) Group, UniSA CHS, University of South Australia, Adelaide, South Australia 5000, Australia; Surface Interactions and Soft Matter (SISM) Group, Future Industries Institute, UniSA STEM, University of South Australia, Mawson Lakes, South Australia 5095, Australia
| | - Stanley J Miklavcic
- Phenomics and Bioinformatics Research Centre, UniSA STEM, University of South Australia, Mawson Lakes, South Australia 5095, Australia
| | - Nathan H Williamson
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, USA.
| | - Anton Blencowe
- Applied Chemistry and Translational Biomaterials (ACTB) Group, UniSA CHS, University of South Australia, Adelaide, South Australia 5000, Australia.
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Carrazzone RJ, Li X, Foster JC, Uppala VVS, Wall CE, Esker AR, Madsen LA, Matson JB. Strong Variation of Micelle-Unimer Coexistence as a Function of Core Chain Mobility. Macromolecules 2021; 54:6975-6981. [PMID: 36910585 PMCID: PMC10004150 DOI: 10.1021/acs.macromol.1c00635] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Polymeric micelles coexist in solution with unassembled chains (unimers). We have investigated the influence of glass transition temperature (T g) (i.e., chain mobility) of the micelle core-forming blocks on micelle-unimer coexistence. We synthesized a series of seven PEG-b-P(nBA-ran-tBA) amphiphilic block copolymers (PEG = poly(ethylene glycol), nBA = n-butyl acrylate, tBA = tert-butyl acrylate) with similar molecular weights (12 kg/mol). Varying the nBA/tBA molar ratio enabled broad modulation of core block T g with no significant change in core hydrophobicity or micelle size. NMR diffusometry revealed increasing unimer populations from 0% to 54% of total polymer concentration upon decreasing core block T g from 25 to -46 °C. Additionally, unimer population at fixed polymer composition (and thus core T g) increased with temperature. This study demonstrates the strong influence of core-forming block mobility on polymer self-assembly, providing information toward designing drug delivery systems and suggesting the need for new dynamical theory.
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Affiliation(s)
- Ryan J Carrazzone
- † Department of Chemistry and Macromolecules Innovation Institute, Virginia Tech, Blacksburg, VA, 24061, United States
| | - Xiuli Li
- † Department of Chemistry and Macromolecules Innovation Institute, Virginia Tech, Blacksburg, VA, 24061, United States
| | - Jeffrey C Foster
- † Department of Chemistry and Macromolecules Innovation Institute, Virginia Tech, Blacksburg, VA, 24061, United States
| | - Veera Venkata Shravan Uppala
- † Department of Chemistry and Macromolecules Innovation Institute, Virginia Tech, Blacksburg, VA, 24061, United States
| | - Candace E Wall
- † Department of Chemistry and Macromolecules Innovation Institute, Virginia Tech, Blacksburg, VA, 24061, United States
| | - Alan R Esker
- † Department of Chemistry and Macromolecules Innovation Institute, Virginia Tech, Blacksburg, VA, 24061, United States
| | - Louis A Madsen
- † Department of Chemistry and Macromolecules Innovation Institute, Virginia Tech, Blacksburg, VA, 24061, United States
| | - John B Matson
- † Department of Chemistry and Macromolecules Innovation Institute, Virginia Tech, Blacksburg, VA, 24061, United States
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Huang GR, Tung CH, Chang D, Lam CN, Do C, Shinohara Y, Chang SY, Wang Y, Hong K, Chen WR. Determining population densities in bimodal micellar solutions using contrast-variation small angle neutron scattering. J Chem Phys 2020; 153:184902. [PMID: 33187411 DOI: 10.1063/5.0024410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Self-assembly of amphiphilic polymers in water is of fundamental and practical importance. Significant amounts of free unimers and associated micellar aggregates often coexist over a wide range of phase regions. The thermodynamic and kinetic properties of the microphase separation are closely related to the relative population density of unimers and micelles. Although the scattering technique has been employed to identify the structure of micellar aggregates as well as their time-evolution, the determination of the population ratio of micelles to unimers remains a challenging problem due to their difference in scattering power. Here, using small-angle neutron scattering (SANS), we present a comprehensive structural study of amphiphilic n-dodecyl-PNIPAm polymers, which shows a bimodal size distribution in water. By adjusting the deuterium/hydrogen ratio of water, the intra-micellar polymer and water distributions are obtained from the SANS spectra. The micellar size and number density are further determined, and the population densities of micelles and unimers are calculated to quantitatively address the degree of micellization at different temperatures. Our method can be used to provide an in-depth insight into the solution properties of microphase separation, which are present in many amphiphilic systems.
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Affiliation(s)
- Guan-Rong Huang
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Chi-Huan Tung
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Dongsook Chang
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Christopher N Lam
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Changwoo Do
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Yuya Shinohara
- Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Shou-Yi Chang
- Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan
| | - Yangyang Wang
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Kunlun Hong
- Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - Wei-Ren Chen
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
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Li BY, Li YC, Lu ZY. The important role of cosolvent in the amphiphilic diblock copolymer self-assembly process. POLYMER 2019. [DOI: 10.1016/j.polymer.2019.03.024] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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