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Pal R, Pattath K. Rheology of Suspensions Thickened by Cellulose Nanocrystals. NANOMATERIALS (BASEL, SWITZERLAND) 2024; 14:1122. [PMID: 38998728 PMCID: PMC11243218 DOI: 10.3390/nano14131122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2024] [Revised: 06/18/2024] [Accepted: 06/28/2024] [Indexed: 07/14/2024]
Abstract
The steady rheological behavior of suspensions of solid particles thickened by cellulose nanocrystals is investigated. Two different types and sizes of particles are used in the preparation of suspensions, namely, TG hollow spheres of 69 µm in Sauter mean diameter and solospheres S-32 of 14 µm in Sauter mean diameter. The nanocrystal concentration varies from 0 to 3.5 wt% and the particle concentration varies from 0 to 57.2 vol%. The influence of salt (NaCl) concentration and pH on the rheology of suspensions is also investigated. The suspensions generally exhibit shear-thinning behavior. The degree of shear-thinning is stronger in suspensions of smaller size particles. The experimental viscosity data are adequately described by a power-law model. The variations in power-law parameters (consistency index and flow behavior index) under different conditions are determined and discussed in detail.
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Affiliation(s)
- Rajinder Pal
- Department of Chemical Engineering, University of Waterloo, Waterloo, ON N2L 3G1, Canada;
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Zhang S, Guo C, Liu B. The Effect of Acid Hydrolysis on the Pickering Emulsifying Capacity of Tartary Buckwheat Flour. Foods 2024; 13:1543. [PMID: 38790843 PMCID: PMC11121274 DOI: 10.3390/foods13101543] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2024] [Revised: 05/07/2024] [Accepted: 05/13/2024] [Indexed: 05/26/2024] Open
Abstract
The effect of sulfuric acid hydrolysis on the Pickering emulsifying capacity of Tartary buckwheat flour (TBF) rich in starch was evaluated for the first time. The results indicate that the sulfuric acid concentration and hydrolysis time had a significant impact on the Pickering emulsifying capacity of acid-hydrolyzed Tartary buckwheat flour (HTBF). A low sulfuric acid concentration (1-2 mol/L) could reduce the particle size of HTBF, but it also decreased the Pickering emulsifying ability. At a sulfuric acid concentration of 3 mol/L, appropriate treatment time (2 and 3 days) led to particle aggregation but significantly improved wettability, thereby resulting in a rapid enhancement in emulsifying capacity. Under these conditions, the obtained HTBF (HTBF-D2-C3 and HTBF-D3-C3) could stabilize medium-chain triglyceride (MCT)-based Pickering high-internal-phase emulsions (HIPEs) with an oil-phase volume fraction of 80% at the addition amounts (c) of ≥1.0% and ≥1.5%, respectively. Its performance was significantly superior to that of TBF (c ≥ 2.0%). Furthermore, at the same addition amount, the droplet size of HIPEs constructed by HTBF-D3-C3 was smaller than that of HTBF-D2-C3, and its gel strength and microrheological performance were also superior to those of HTBF-D2-C3, which was attributed to the higher wettability of HTBF-D3-C3. The findings of this study can facilitate the in-depth application of Tartary buckwheat and provide references for the development of novel Pickering emulsifiers.
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Affiliation(s)
| | | | - Benguo Liu
- School of Food Science, Henan Institute of Science and Technology, Xinxiang 453003, China; (S.Z.); (C.G.)
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Badruddoza AZM, Yeoh T, Shah JC, Walsh T. Assessing and Predicting Physical Stability of Emulsion-Based Topical Semisolid Products: A Review. J Pharm Sci 2023; 112:1772-1793. [PMID: 36966902 DOI: 10.1016/j.xphs.2023.03.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2023] [Revised: 03/20/2023] [Accepted: 03/21/2023] [Indexed: 03/30/2023]
Abstract
The emulsion-based topical semisolid dosage forms present a high degree of complexity due to their microstructures which is apparent from their compositions comprising at least two immiscible liquid phases, often times of high viscosity. These complex microstructures are thermodynamically unstable, and the physical stability of such preparations is governed by formulation parameters such as phase volume ratio, type of emulsifiers and their concentration, HLB value of the emulsifier, as well as by process parameters such as homogenizer speed, time, temperature etc. Therefore, a detailed understanding of the microstructure in the DP and critical factors that influence the stability of emulsions is essential to ensure the quality and shelf-life of emulsion-based topical semisolid products. This review aims to provide an overview of the main strategies used to stabilize pharmaceutical emulsions contained in semisolid products and various characterization techniques and tools that have been utilized so far to evaluate their long-term stability. Accelerated physical stability assessment using dispersion analyzer tools such as an analytical centrifuge to predict the product shelf-life has been discussed. In addition, mathematical modeling for phase separation rate for non-Newtonian systems like semisolid emulsion products has also been discussed to guide formulation scientists to predict a priori stability of these products.
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Affiliation(s)
- Abu Zayed Md Badruddoza
- Drug Product Design, Worldwide Research, Development and Medical, Pfizer Inc., Groton, CT 06340, USA.
| | - Thean Yeoh
- Drug Product Design, Worldwide Research, Development and Medical, Pfizer Inc., Groton, CT 06340, USA
| | - Jaymin C Shah
- Drug Product Design, Worldwide Research, Development and Medical, Pfizer Inc., Groton, CT 06340, USA
| | - Taylor Walsh
- Eurofins Lancaster Laboratories Professional Scientific Services, 2425 New Holland Pike, Lancaster, PA 17601, USA
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Biopolymer-based emulsions for the stabilization of Trichoderma atrobrunneum conidia for biological control. Appl Microbiol Biotechnol 2023; 107:1465-1476. [PMID: 36683057 PMCID: PMC9898383 DOI: 10.1007/s00253-023-12381-y] [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: 12/13/2022] [Revised: 01/06/2023] [Accepted: 01/09/2023] [Indexed: 01/24/2023]
Abstract
Trichoderma spp. are ubiquitous soil-borne fungi that are widely used in biological control to promote and regulate healthy plant growth, as well as protect against plant pathogens. However, as with many biological materials, the relative instability of Trichoderma propagules limits its practical use in industrial applications. Therefore, there has been significant research interest in developing novel formulations with various carrier substances that are compatible with these fungal propagules and can enhance the shelf-life and overall efficacy of the Trichoderma. To this end, herein, we investigate the use of a variety of biopolymers and nanoparticles for the stabilization of Trichoderma atrobrunneum T720 conidia for biological control. The best-performing agents-agar and cellulose nanocrystals (CNC)-were then used in the preparation of oil-in-water emulsions to encapsulate conidia of T720. Emulsion properties including oil type, oil:water ratio, and biopolymer/particle concentration were investigated with respect to emulsion stability, droplet size, and viability of T720 conidia over time. Overall, agar-based formulations yielded highly stable emulsions with small droplet sizes, showing no evidence of drastic creaming, or phase separation after 1 month of storage. Moreover, agar-based formulations were able to maintain ~ 100% conidial viability of T720 after 3 months of storage, and over 70% viability after 6 months. We anticipate that the results demonstrated herein will lead to a new generation of significantly improved formulations for practical biological control applications. KEY POINTS: • Various biopolymers were evaluated for improving the stability of Trichoderma conidia • Oil in water emulsions was prepared using cellulose nanocrystals and agar as interface stabilizers • Agar-based emulsions showed ~ 100% viability for encapsulated conidia after 3 months of storage.
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Pal A, Pal R. Rheology of Emulsions Thickened by Starch Nanoparticles. NANOMATERIALS 2022; 12:nano12142391. [PMID: 35889614 PMCID: PMC9317011 DOI: 10.3390/nano12142391] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/05/2022] [Revised: 07/07/2022] [Accepted: 07/11/2022] [Indexed: 02/05/2023]
Abstract
The rheology of oil-in-water (O/W) emulsions thickened by starch nanoparticles is investigated here. The starch nanoparticle concentration is varied from 0 to 25 wt% based on the matrix aqueous phase. The oil concentration is varied from 0 to 65 wt%. At a given nanoparticle concentration, the emulsions are generally Newtonian at low oil concentrations. The emulsions become shear-thinning at high oil concentrations. The increase in nanoparticle concentration at a given oil concentration increases the consistency of the emulsion and enhances the shear-thinning behavior of emulsion. The rheological behavior of emulsions is described reasonably well by a power-law model. The consistency index of the emulsion increases with the increases in nanoparticle and oil concentrations. The flow behavior index of emulsion decreases with the increases in nanoparticle and oil concentrations, indicating an increase in the degree of shear-thinning in emulsion.
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Stock S, Jakob F, Röhl S, Gräff K, Kühnhammer M, Hondow N, Micklethwaite S, Kraume M, von Klitzing R. Exploring water in oil emulsions simultaneously stabilized by solid hydrophobic silica nanospheres and hydrophilic soft PNIPAM microgel. SOFT MATTER 2021; 17:8258-8268. [PMID: 34550151 DOI: 10.1039/d1sm00942g] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
A general drawback of microgels is that they do not stabilize water-in-oil (w/o) emulsions of non-polar oils. Simultaneous stabilization with solid hydrophobic nanoparticles and soft hydrophilic microgels overcomes this problem. For a fundamental understanding of this synergistic effect the use of well defined particle systems is crucial. Therefore, the present study investigates the stabilization of water droplets in a highly non-polar oil phase using temperature responsive, soft and hydrophilic PNIPAM microgel particles (MGs) and solid and hydrophobic silica nanospheres (SNs) simultaneously. The SNs are about 20 times smaller than the MGs. In a multiscale approach the resulting emulsions are studied from the nanoscale particle properties over microscale droplet sizes to macroscopic observations. The synergy of the particles allows the stabilization of water-in-oil (w/o) emulsions, which was not possible with MGs alone, and offers a larger internal interface than the stabilization with SNs alone. Furthermore, the incorporation of hydrophilic MGs into a hydrophobic particle layer accelerates the emulsions sedimentation speed. Nevertheless, the droplets are still sufficiently protected against coalescence even in the sediment and can be redispersed by gentle shaking. Based on droplet size measurements and cryo-SEM studies we elaborate a model, which explains the found phenomena.
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Affiliation(s)
- Sebastian Stock
- Institute for Condensed Matter Physics, Technische Universität Darmstadt, Darmstadt, Germany.
| | - Franziska Jakob
- Institute for Condensed Matter Physics, Technische Universität Darmstadt, Darmstadt, Germany.
| | - Susanne Röhl
- Chair of Chemical and Process Engineering, Technische Universität Berlin, Berlin, Germany
| | - Kevin Gräff
- Institute for Condensed Matter Physics, Technische Universität Darmstadt, Darmstadt, Germany.
| | - Matthias Kühnhammer
- Institute for Condensed Matter Physics, Technische Universität Darmstadt, Darmstadt, Germany.
| | - Nicole Hondow
- School of Chemical and Process Engineering, University of Leeds, Leeds, UK
| | | | - Matthias Kraume
- Chair of Chemical and Process Engineering, Technische Universität Berlin, Berlin, Germany
| | - Regine von Klitzing
- Institute for Condensed Matter Physics, Technische Universität Darmstadt, Darmstadt, Germany.
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Cho YS, Lee SH, Seo HM, Shin K, Kang MH, Lee M, Park J, Kim JW. Structuring Pickering Emulsion Interfaces with Bilayered Coacervates of Cellulose Nanofibers and Hectorite Nanoplatelets. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:3828-3835. [PMID: 33780257 DOI: 10.1021/acs.langmuir.0c03082] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
In this study, we present a water-in-silicone oil (W/S) Pickering emulsion system stabilized via in situ interfacial coacervation of attractive hectorite nanoplatelets (AHNPs) and bacterial cellulose nanofibrils (BCNFs). A bilayered coacervate is generated at the W/S interface by employing the controlled electrostatic interaction between the positively charged AHNPs and the negatively charged BCNFs. The W/S interface with the bilayered coacervate shows a significant increase in the interfacial modulus by 2 orders of magnitude than that with the AHNPs only. In addition, we observe that water droplets are interconnected by the BCNF bridging across the continuous phase of silicon, which is attributed to the diffusive transport phenomenon. This droplet interconnection results in the effective prevention of drop coalescence, which is confirmed via emulsion sedimentation kinetics. These results indicate that our bilayered coacervation technology has the potential of developing a promising Pickering emulsion platform that can be used in the pharmaceutical and cosmetic industries.
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Affiliation(s)
- Yeong Sik Cho
- School of Chemical Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Sung Ho Lee
- School of Chemical Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea
- Sunjin Beauty Science Co., Ansan 15612, Republic of Korea
| | - Hye Min Seo
- School of Chemical Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Kyounghee Shin
- School of Chemical Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea
| | - Min Ho Kang
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- School of Chemical and Biological Engineering and Institute of Chemical Processes, Seoul National University, Seoul 08826, Republic of Korea
| | - Minyoung Lee
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- School of Chemical and Biological Engineering and Institute of Chemical Processes, Seoul National University, Seoul 08826, Republic of Korea
| | - Jungwon Park
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea
- School of Chemical and Biological Engineering and Institute of Chemical Processes, Seoul National University, Seoul 08826, Republic of Korea
| | - Jin Woong Kim
- School of Chemical Engineering, Sungkyunkwan University, Suwon 16419, Republic of Korea
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Droplet coalescence and phase separation in a topical ointment: Effects of fluid shear and temperature. Int J Pharm 2020; 591:119872. [DOI: 10.1016/j.ijpharm.2020.119872] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 09/03/2020] [Accepted: 09/06/2020] [Indexed: 11/30/2022]
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Effects of Bentonite Nanoclay and Cetyltrimethyl Ammonium Bromide Modified Bentonite Nanoclay on Phase Inversion of Water-in-Oil Emulsions. COLLOIDS AND INTERFACES 2020. [DOI: 10.3390/colloids4010002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The effects of unmodified and modified bentonite nanoclays (with various degrees of surfactant modification) on the catastrophic phase inversion from water-in-oil (W/O) emulsion to oil-in-water (O/W) emulsion were determined experimentally. The bentonite nanoclay (NC-Bt) was suspended in the aqueous phase, and the critical volume fraction of water where phase inversion from W/O to O/W emulsion took place was determined through conductivity measurements. Cetyltrimethyl ammonium bromide (CTAB) was used as a surfactant to modify the nanoclay. The adsorption of CTAB onto nanoclay had a strong influence on the contact angle and the critical volume fraction of water where phase inversion took place. The modification of the nanoclay brought about by the adsorption of CTAB increased the three-phase contact angle (measured through the aqueous phase), thereby making it more hydrophobic, and prolonged the phase inversion point. CTAB alone and CTAB-modified nanoclay delayed the phase inversion process in a similar manner, showing a strong dependence on the CTAB concentration.
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