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Esposito R, Cavasso D, Niccoli M, D’Errico G. Phase Inversion and Interfacial Layer Microstructure in Emulsions Stabilized by Glycosurfactant Mixtures. Nanomaterials (Basel) 2021; 11:331. [PMID: 33513926 PMCID: PMC7911527 DOI: 10.3390/nano11020331] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 01/20/2021] [Accepted: 01/22/2021] [Indexed: 02/05/2023]
Abstract
Identification of strategies to prolong emulsion kinetic stability is a fundamental challenge for many scientists and technologists. We investigated the relationship between the emulsion stability and the surfactant supramolecular organization at the oil-water interface. The pseudo-phase diagrams of emulsions formed by water and, alternatively, a linear or a branched oil, stabilized by mixtures of two sugar-based surfactants, Span80 and Tween80, are presented. The surfactant ordering and dynamics were analyzed by electron paramagnetic resonance (EPR) spectroscopy. In Oil-in-Water (O/W) emulsions, which are stable for more than four days, disordered surfactant tails formed a compact and viscous layer. In Water-in-Oil (W/O) emulsions, whose stability is much lower, surfactants formed an ordered layer of extended tails pointing toward the continuous apolar medium. If linear oil was used, a narrow range of surfactant mixture composition existed, in which emulsions did not demix in the whole range of water/oil ratio, thus making it possible to study the phase inversion from O/W to W/O structures. While conductometry showed an abrupt inversion occurring at a well-defined water/oil ratio, the surfactant layer microstructure changed gradually between the two limiting situations. Overall, our results demonstrate the interconnection between the emulsion stability and the surfactant layer microstructuring, thus indicating directions for their rational design.
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Affiliation(s)
- Rodolfo Esposito
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia 4, Complesso Universitario di Monte Sant’Angelo, I-80126 Naples, Italy; (R.E.); (D.C.); (M.N.)
| | - Domenico Cavasso
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia 4, Complesso Universitario di Monte Sant’Angelo, I-80126 Naples, Italy; (R.E.); (D.C.); (M.N.)
| | - Marcella Niccoli
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia 4, Complesso Universitario di Monte Sant’Angelo, I-80126 Naples, Italy; (R.E.); (D.C.); (M.N.)
| | - Gerardino D’Errico
- Department of Chemical Sciences, University of Naples Federico II, Via Cintia 4, Complesso Universitario di Monte Sant’Angelo, I-80126 Naples, Italy; (R.E.); (D.C.); (M.N.)
- Consorzio Interuniversitario per lo Sviluppo dei Sistemi a Grande Interfase (CSGI), Via della Lastruccia 3, I-50019 Florence, Italy
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Kushwah V, Saraf I, Yeoh T, Ardelean I, Weber H, Sarkar A, Chen R, Vogel T, Modhave D, Laggner P, Paudel A. Interplay of Aging and Lot-to-Lot Variability on the Physical and Chemical Properties of Excipients: A Case Study of Mono- and Diglycerides. Mol Pharm 2021; 18:862-877. [PMID: 33475378 DOI: 10.1021/acs.molpharmaceut.0c00847] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The present study investigates the chemical composition governing the physical properties of mono- and diglycerides (MDGs) at the microstructural level, as a function of aging and lot-to-lot variability. The physical structure of the MDG plays a vital role in ameliorating the emulsion stability and is widely explored in diverse research horizons related to the pharmaceutical, cosmetic, and food industries. In an effort to understand the mechanism of emulsion stabilization, physical properties were extensively evaluated in selective commercial lots to determine if there is a correlation between the chemical composition of MDG and physical properties. The solid state of the MDG samples with different aging profiles was characterized using X-ray scattering, differential scanning calorimetry, attenuated total reflection-Fourier transform infrared spectroscopy, and NMR relaxometry. Moreover, the kinetic aspect of solid-state transformation was also evaluated via treating MDG samples with a heat-cool cycle. The chemical composition of MDGs was quantified using a quantitative NMR (qNMR) method. Interestingly, the X-ray scattering results demonstrated a change in the MDG polymorphic form and an increase in the %β content as a function of aging. The increase in the %β content led to the formation of rigid crystal structures of MDG, as evident from the NMR relaxometry. Chemical quantification of isomeric composition revealed chemical composition change as a potentially critical factor responsible for the altered physical structures of MDG with respect to aging and lot-to-lot variability. The findings correlated the solid-state transformation with the change in the chemical composition of the MDG as a combined effect of aging and lot-to-lot variability. This work serves as a basis to better understand the interdependency of the physicochemical properties of MDG. Furthermore, the present work can also be used as guidance for setting up the specifications of MDG, as per the required polymorphic form for a multitude of applications.
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Affiliation(s)
- Varun Kushwah
- Research Center Pharmaceutical Engineering (RCPE) GmbH, Inffeldgasse 13, 8010 Graz, Austria
| | - Isha Saraf
- Research Center Pharmaceutical Engineering (RCPE) GmbH, Inffeldgasse 13, 8010 Graz, Austria
| | - Thean Yeoh
- Drug Product Design, Worldwide Research, Development and Medical, Pfizer Inc., Groton, Connecticut 06340, United States
| | - Ioan Ardelean
- Department of Physics and Chemistry, Technical University of Cluj-Napoca, Cluj-Napoca 400084, Romania
| | - Hansjoerg Weber
- Institute of Organic Chemistry, Graz University of Technology, Stremayrgasse 9A, 8010 Graz, Austria
| | - Avik Sarkar
- Drug Product Design, Worldwide Research, Development and Medical, Pfizer Inc., Groton, Connecticut 06340, United States
| | - Raymond Chen
- Analytical R&D, Worldwide Research, Development and Medical, Pfizer Inc., Groton, Connecticut 06340, United States
| | - Trevor Vogel
- Drug Product Design, Worldwide Research, Development and Medical, Pfizer Inc., Groton, Connecticut 06340, United States
| | - Dattatray Modhave
- Research Center Pharmaceutical Engineering (RCPE) GmbH, Inffeldgasse 13, 8010 Graz, Austria
| | - Peter Laggner
- Research Center Pharmaceutical Engineering (RCPE) GmbH, Inffeldgasse 13, 8010 Graz, Austria
| | - Amrit Paudel
- Research Center Pharmaceutical Engineering (RCPE) GmbH, Inffeldgasse 13, 8010 Graz, Austria.,Institute for Process and Particle Engineering, Graz University of Technology, Inffeldgasse 13, 8010 Graz, Austria
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Affiliation(s)
- Peng Xu
- State
Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Xu Zheng
- State
Key Laboratory of Nonlinear Mechanics, Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China
| | - Yi Tao
- State
Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
| | - Wenbin Du
- State
Key Laboratory of Microbial Resources, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China
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