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Sundar S, Nirmal G, Borkar S, Goel S, Ramachandran K, Kochhar R, Hukkanen EJ, Chiarella RA, Ramachandran A. Microfluidic extensional flow device to study mass transfer dynamics in the polymer microparticle formation process. SOFT MATTER 2024; 20:6140-6149. [PMID: 39041251 DOI: 10.1039/d4sm00492b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/24/2024]
Abstract
Polymer microparticles are often used to encapsulate drugs for sustained drug-release treatments. One of the ways they are manufactured is by using a solvent extraction process, in which the polymer solution is emulsified into an aqueous bulk phase using a surfactant as a stabilizing agent, followed by the removal of the solvent. The radius of a polymer drop decreases as a function of time until the polymer reaches the gelling point, after which it is separated and dried. Among the various operating parameters, the rate of solvent extraction is a critical step that affects the morphology and porosity, and consequently, the kinetics of drug release. But a fundamental mechanistic understanding of the solvent extraction dynamics as a function of shear is still unexplored. In this study, we have developed an experimental mass transfer model to predict the extraction by using the microfluidic extensional flow device (MEFD) to probe the shear and extraction dynamics at the level of a single drop in a linear extensional flow field. We used a computer-controlled feedback algorithm to manipulate the flow field and hydrodynamically trap a Hele-Shaw drop and observe the extraction process. For the polymer solution, we used a biocompatible polymer, poly-lactic-co-glycolic acid (PLGA) with ethyl acetate (EtOAc) as the solvent. Our experiments were conducted by varying the extensional rate (G) in the channel from ∼0.1 s-1 to ∼10 s-1, and using an analytical solution of the flow field, we captured the dissolution process and measured the change in drop radius (R) with time (t). Interestingly, we initially observed a short-time asymptote R ∼ t, and later the long-time asymptote of R = constant; both trends were physically explained. The transport model developed in this work can be used to predict extraction rates and polymer microparticle composition for any polymer-solvent system. This work is also an important contribution to the literature on convective mass transfer in partially miscible emulsions.
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Affiliation(s)
- Suryavarshini Sundar
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, ON M5S 3E5, Canada.
| | - Ghata Nirmal
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, ON M5S 3E5, Canada.
| | - Suraj Borkar
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, ON M5S 3E5, Canada.
| | - Sachin Goel
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, ON M5S 3E5, Canada.
| | - Karthik Ramachandran
- Pharmaceutical Development, Alkermes, Inc., 900 Winter St, Waltham, MA 02451, USA
| | - Ransom Kochhar
- Pharmaceutical Development, Alkermes, Inc., 900 Winter St, Waltham, MA 02451, USA
| | - Eric J Hukkanen
- Pharmaceutical Development, Alkermes, Inc., 900 Winter St, Waltham, MA 02451, USA
| | - Renato A Chiarella
- Pharmaceutical Development, Alkermes, Inc., 900 Winter St, Waltham, MA 02451, USA
| | - Arun Ramachandran
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, ON M5S 3E5, Canada.
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Ruiken JP, Villwock J, Kraume M. Drop Dissolution Intensified by Acoustic Levitation. MICROMACHINES 2024; 15:805. [PMID: 38930775 PMCID: PMC11205613 DOI: 10.3390/mi15060805] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2024] [Revised: 06/12/2024] [Accepted: 06/18/2024] [Indexed: 06/28/2024]
Abstract
Acoustic levitation can provide significant benefits for many fundamental research questions. However, it is important to consider that the acoustic field influences the measurement environment. This work focuses on the dissolution of immobilised drops using acoustic levitation in liquid-liquid systems. Previous work demonstrated that the acoustic field of standing waves impacts mass transfer by affecting the spread of dissolved substances in the continuous phase in two distinct ways: (I) solutes may either pass through nodal planes of the standing waves or (II) not pass. The binary systems examined for case (I) are 1-hexanol-water and 1-butanol-water, and for case (II), n-butyl acetate-water and toluene-water. This work quantifies the intensification effect of acoustic levitation on dissolution for the two types of behaviour, by comparing them with reference measurements of mechanically attached dissolving drops. The system was designed to ensure minimal intensification. The minimum intensification of mass transfer for levitating drops in the used setup of case (I) was 25%, and for case (II), it was 65%, both increasing with decreasing surface-equivalent diameter. With this understanding, acoustic levitation can be used more accurately in the field of mass transfer studies.
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Affiliation(s)
| | - Jörn Villwock
- Department of Chemical and Process Engineering, Technische Universität Berlin, Ackerstr. 76, 13355 Berlin, Germany; (J.-P.R.); (M.K.)
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3
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Ramezanzadeh M, Slowinski S, Rezanezhad F, Murr K, Lam C, Smeaton C, Alibert C, Vandergriendt M, Van Cappellen P. Effects of freeze-thaw cycles on methanogenic hydrocarbon degradation: Experiment and modeling. CHEMOSPHERE 2023; 325:138405. [PMID: 36931401 DOI: 10.1016/j.chemosphere.2023.138405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Revised: 03/08/2023] [Accepted: 03/13/2023] [Indexed: 06/18/2023]
Abstract
Cold regions are warming much faster than the global average, resulting in more frequent and intense freeze-thaw cycles (FTCs) in soils. In hydrocarbon-contaminated soils, FTCs modify the biogeochemical and physical processes controlling petroleum hydrocarbon (PHC) biodegradation and the associated generation of methane (CH4) and carbon dioxide (CO2). Thus, understanding the effects of FTCs on the biodegradation of PHCs is critical for environmental risk assessment and the design of remediation strategies for contaminated soils in cold regions. In this study, we developed a diffusion-reaction model that accounts for the effects of FTCs on toluene biodegradation, including methanogenic biodegradation. The model is verified against data generated in a 215 day-long batch experiment with soil collected from a PHC contaminated site in Ontario, Canada. The fully saturated soil incubations with six different treatments were exposed to successive 4-week FTCs, with temperatures oscillating between -10 °C and +15 °C, under anoxic conditions to stimulate methanogenic biodegradation. We measured the headspace concentrations and 13C isotope compositions of CH4 and CO2 and analyzed the porewater for pH, acetate, dissolved organic and inorganic carbon, and toluene. The numerical model represents solute diffusion, volatilization, sorption, as well as a reaction network of 13 biogeochemical processes. The model successfully simulates the soil porewater and headspace concentration time series data by representing the temperature dependencies of microbial reaction and gas diffusion rates during FTCs. According to the model results, the observed increases in the headspace concentrations of CH4 and CO2 by 87% and 136%, respectively, following toluene addition are explained by toluene fermentation and subsequent methanogenesis reactions. The experiment and the numerical simulation show that methanogenic degradation is the primary toluene attenuation mechanism under the electron acceptor-limited conditions experienced by the soil samples, representing 74% of the attenuation, with sorption contributing to 11%, and evaporation contributing to 15%. Also, the model-predicted contribution of acetate-based methanogenesis to total produced CH4 agrees with that derived from the 13C isotope data. The freezing-induced soil matrix organic carbon release is considered as an important process causing DOC increase following each freezing period according to the calculations of carbon balance and SUVA index. The simulation results of a no FTC scenario indicate that, in the absence of FTCs, CO2 and CH4 generation would decrease by 29% and 26%, respectively, and that toluene would be biodegraded 23% faster than in the FTC scenario. Because our modeling approach represents the dominant processes controlling PHC biodegradation and the associated CH4 and CO2 fluxes, it can be used to analyze the sensitivity of these processes to FTC frequency and duration driven by temperature fluctuations.
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Affiliation(s)
- Mehdi Ramezanzadeh
- Ecohydrology Research Group, Department of Earth and Environmental Sciences and Water Institute, University of Waterloo, Canada.
| | - Stephanie Slowinski
- Ecohydrology Research Group, Department of Earth and Environmental Sciences and Water Institute, University of Waterloo, Canada
| | - Fereidoun Rezanezhad
- Ecohydrology Research Group, Department of Earth and Environmental Sciences and Water Institute, University of Waterloo, Canada
| | - Kathleen Murr
- Ecohydrology Research Group, Department of Earth and Environmental Sciences and Water Institute, University of Waterloo, Canada
| | - Christina Lam
- Ecohydrology Research Group, Department of Earth and Environmental Sciences and Water Institute, University of Waterloo, Canada
| | - Christina Smeaton
- School of Science and the Environment, Grenfell Campus, Memorial University of Newfoundland, Canada
| | - Clement Alibert
- Ecohydrology Research Group, Department of Earth and Environmental Sciences and Water Institute, University of Waterloo, Canada
| | - Marianne Vandergriendt
- Ecohydrology Research Group, Department of Earth and Environmental Sciences and Water Institute, University of Waterloo, Canada
| | - Philippe Van Cappellen
- Ecohydrology Research Group, Department of Earth and Environmental Sciences and Water Institute, University of Waterloo, Canada
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Day JR, Heidrich ES, Wood TS. A scalable model of fluid flow, substrate removal and current production in microbial fuel cells. CHEMOSPHERE 2022; 291:132686. [PMID: 34740702 DOI: 10.1016/j.chemosphere.2021.132686] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 09/24/2021] [Accepted: 10/23/2021] [Indexed: 06/13/2023]
Abstract
Mathematical modelling can reduce the cost and time required to design complex systems, and is being increasingly used in microbial electrochemical technologies (METs). To be of value such models must be complex enough to reproduce important behaviour of MET, yet simple enough to provide insight into underlying causes of this behaviour. Ideally, models must also be scalable to future industrial applications, rather than limited to describing existing laboratory experiments. We present a scalable model for simulating both fluid flow and bioelectrochemical processes in microbial fuel cells (MFCs), benchmarking against an experimental pilot-scale bioreactor. The model describes substrate transport through a two-dimensional fluid domain, and biofilm growth on anode surfaces. Electron transfer is achieved by an intracellular redox mediator. We find significant spatial variations in both substrate concentration and current density. Simple changes to the reactor layout can greatly improve the overall efficiency, measured in terms of substrate removal and total current generated.
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Affiliation(s)
- Jordan R Day
- Newcastle University, School of Engineering, NE1 7RU, Newcastle-upon-Tyne, UK.
| | | | - Toby S Wood
- Newcastle University, School of Mathematics, Statistics and Physics, NE17RU, Newcastle-upon-Tyne, UK
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Abstract
Water in oil emulsions have a wide range of applications from chemical technology to microfluidics, where the stability of water droplets is of paramount importance. Here, using an accessible and easily reproducible experimental setup we describe and characterize the dissolution of water in oil, which renders nanoliter-sized droplets unstable, resulting in their shrinkage and disappearance in a time scale of hours. This process has applicability in creating miniature reactors for crystallization. We test multiple oils and their combinations with surfactants exhibiting widely different rates of dissolution. We derived simple analytical equations to determine the product of the diffusion coefficient and the relative saturation density of water in oil from the measured dissolution data. By measuring the moisture content of mineral and silicone oils with Karl Fischer titration before and after saturating them with water, we calculated the diffusion coefficient of water in these two oils.
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Needham D. The pH Dependence of Niclosamide Solubility, Dissolution, and Morphology: Motivation for Potentially Universal Mucin-Penetrating Nasal and Throat Sprays for COVID19, its Variants and other Viral Infections. Pharm Res 2021; 39:115-141. [PMID: 34962625 PMCID: PMC8713544 DOI: 10.1007/s11095-021-03112-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 09/14/2021] [Indexed: 11/03/2022]
Abstract
Motivation With the coronavirus pandemic still raging, prophylactic-nasal and early-treatment throat-sprays could help prevent infection and reduce viral load. Niclosamide has the potential to treat a broad-range of viral infections if local bioavailability is optimized as mucin-penetrating solutions that can reach the underlying epithelial cells. Experimental pH-dependence of supernatant concentrations and dissolution rates of niclosamide were measured in buffered solutions by UV/Vis-spectroscopy for niclosamide from different suppliers (AK Sci and Sigma), as precipitated material, and as cosolvates. Data was compared to predictions from Henderson-Hasselbalch and precipitation-pH models. Optical-microscopy was used to observe the morphologies of original, converted and precipitated niclosamide. Results Niclosamide from the two suppliers had different polymorphs resulting in different dissolution behavior. Supernatant concentrations of the “AKSci-polymorph” increased with increasing pH, from 2.53μM at pH 3.66 to 300μM at pH 9.2, reaching 703μM at pH 9.63. However, the “Sigma-polymorph” equilibrated to much lower final supernatant concentrations, reflective of more stable polymorphs at each pH. Similarly, when precipitated from supersaturated solution, or as cosolvates, niclosamide also equilibrated to lower final supernatant concentrations. Polymorph equilibration though was avoided by using a solvent-exchange technique to make the solutions. Conclusions Given niclosamide’s activity as a host cell modulator, optimized niclosamide solutions could represent universal prophylactic nasal and early treatment throat sprays against COVID19, its more contagious variants, and other respiratory viral infections. They are the simplest and potentially most effective formulations from both an efficacy standpoint as well as manufacturing and distribution, (no cold chain). They now just need testing. Supplementary Information The online version contains supplementary material available at 10.1007/s11095-021-03112-x.
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Affiliation(s)
- David Needham
- Department of Mechanical Engineering and Material Science, Duke University, Durham, North Carolina, 27708, USA. .,Professor of Translational Therapeutics, School of Pharmacy, University of Nottingham, Nottingham, NG7 2RD, UK.
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Pham VN, Radajewski D, Rodríguez-Ruiz I, Teychene S. Microfluidics: A Novel Approach for Dehydration Protein Droplets. BIOSENSORS 2021; 11:bios11110460. [PMID: 34821675 PMCID: PMC8615364 DOI: 10.3390/bios11110460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 11/10/2021] [Accepted: 11/15/2021] [Indexed: 11/16/2022]
Abstract
The equation of state of colloids plays an important role in the modelling and comprehension of industrial processes, defining the working conditions of processes such as drying, filtration, and mixing. The determination of the equation is based on the solvent equilibration, by dialysis, between the colloidal suspension and a reservoir with a known osmotic pressure. In this paper, we propose a novel microfluidic approach to determine the equation of state of a lysozyme solution. Monodispersed droplets of lysozyme were generated in the bulk of a continuous 1-decanol phase using a flow-focusing microfluidic geometry. In this multiphasic system and in the working operation conditions, the droplets can be considered to act as a permeable membrane system. A water mass transfer flow occurs by molecule continuous diffusion in the surrounding 1-decanol phase until a thermodynamic equilibrium is reached in a few seconds to minutes, in contrast with the standard osmotic pressure measurements. By changing the water saturation of the continuous phase, the equation of state of lysozyme in solution was determined through the relation of the osmotic pressure between protein molecules and the volume fraction of protein inside the droplets. The obtained equation shows good agreement with other standard approaches reported in the literature.
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Affiliation(s)
- Van Nhat Pham
- Graduate University of Science and Technology (GUST), Vietnam Academy of Science and Technology, Hanoi 10072, Vietnam;
- Department of Advanced Materials Science and Nanotechnology, Vietnam Academy of Science and Technology, University of Science and Technology of Hanoi (USTH), Hanoi 10072, Vietnam
| | - Dimitri Radajewski
- Laboratoire de Génie Chimique, UMR 5503, 4 allée Emile Monso, 31432 Toulouse, France; (D.R.); (I.R.-R.)
| | - Isaac Rodríguez-Ruiz
- Laboratoire de Génie Chimique, UMR 5503, 4 allée Emile Monso, 31432 Toulouse, France; (D.R.); (I.R.-R.)
| | - Sebastien Teychene
- Laboratoire de Génie Chimique, UMR 5503, 4 allée Emile Monso, 31432 Toulouse, France; (D.R.); (I.R.-R.)
- Correspondence:
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8
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Interfacial Mass Transfer in Trichloroethylene/Surfactants/ Water Systems: Implications for Remediation Strategies. REACTIONS 2021. [DOI: 10.3390/reactions2030020] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The fate of dense non-aqueous phase liquids (DNAPLs) in the environment and the consequential remediation problems have been intensively studied over the last 50 years. However, a scarce literature is present about the mass transfer at the DNAPL/water interface. In this paper, we present a fast method for the evaluation of the mass transfer performance of a surfactant that can easily be employed to support an effective choice for the so-called enhanced remediation strategies. We developed a lab-scale experimental system modelled by means of simple ordinary differential equations to calculate the mass transfer coefficient (K) of trichloroethylene, chosen as representative DNAPL, in the presence and in the absence of two ethoxylated alcohols belonging to the general class of Synperonic surfactants. Our findings revealed that it exists an optimal surfactant concentration range, where K increases up to 40% with respect to pure water.
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Henshaw CA, Dundas AA, Cuzzucoli Crucitti V, Alexander MR, Wildman R, Rose FRAJ, Irvine DJ, Williams PM. Droplet Microfluidic Optimisation Using Micropipette Characterisation of Bio-Instructive Polymeric Surfactants. Molecules 2021; 26:3302. [PMID: 34072733 PMCID: PMC8197901 DOI: 10.3390/molecules26113302] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 05/25/2021] [Accepted: 05/27/2021] [Indexed: 11/24/2022] Open
Abstract
Droplet microfluidics can produce highly tailored microparticles whilst retaining monodispersity. However, these systems often require lengthy optimisation, commonly based on a trial-and-error approach, particularly when using bio-instructive, polymeric surfactants. Here, micropipette manipulation methods were used to optimise the concentration of bespoke polymeric surfactants to produce biodegradable (poly(d,l-lactic acid) (PDLLA)) microparticles with unique, bio-instructive surface chemistries. The effect of these three-dimensional surfactants on the interfacial tension of the system was analysed. It was determined that to provide adequate stabilisation, a low level (0.1% (w/v)) of poly(vinyl acetate-co-alcohol) (PVA) was required. Optimisation of the PVA concentration was informed by micropipette manipulation. As a result, successful, monodisperse particles were produced that maintained the desired bio-instructive surface chemistry.
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Affiliation(s)
- Charlotte A. Henshaw
- Molecular Therapeutics and Formulation, School of Pharmacy, University of Nottingham, Nottingham NG7 2RD, UK;
- Advanced Materials and Healthcare Technologies, School of Pharmacy, University of Nottingham, Nottingham NG7 2RD, UK; (A.A.D.); (M.R.A.)
| | - Adam A. Dundas
- Advanced Materials and Healthcare Technologies, School of Pharmacy, University of Nottingham, Nottingham NG7 2RD, UK; (A.A.D.); (M.R.A.)
- Centre for Additive Manufacturing, Department for Chemical and Environmental Engineering, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, UK; (V.C.C.); (R.W.)
| | - Valentina Cuzzucoli Crucitti
- Centre for Additive Manufacturing, Department for Chemical and Environmental Engineering, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, UK; (V.C.C.); (R.W.)
| | - Morgan R. Alexander
- Advanced Materials and Healthcare Technologies, School of Pharmacy, University of Nottingham, Nottingham NG7 2RD, UK; (A.A.D.); (M.R.A.)
| | - Ricky Wildman
- Centre for Additive Manufacturing, Department for Chemical and Environmental Engineering, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, UK; (V.C.C.); (R.W.)
| | - Felicity R. A. J. Rose
- Regenerative Medicine and Cellular Therapies, School of Pharmacy, University of Nottingham, Nottingham NG7 2RD, UK;
| | - Derek J. Irvine
- Centre for Additive Manufacturing, Department for Chemical and Environmental Engineering, Faculty of Engineering, University of Nottingham, Nottingham NG7 2RD, UK; (V.C.C.); (R.W.)
| | - Philip M. Williams
- Molecular Therapeutics and Formulation, School of Pharmacy, University of Nottingham, Nottingham NG7 2RD, UK;
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Borden MA, Shakya G, Upadhyay A, Song KH. Acoustic Nanodrops for Biomedical Applications. Curr Opin Colloid Interface Sci 2020; 50:101383. [PMID: 33100885 PMCID: PMC7581261 DOI: 10.1016/j.cocis.2020.08.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Acoustic nanodrops are designed to vaporize into ultrasound-responsive microbubbles, which presents certain challenges nonexistent for conventional nano-emulsions. The requirements of biocompatibility, vaporizability and colloidal stability has focused research on perfluorocarbons (PFCs). Shorter PFCs yield better vaporizability via their lower critical temperature, but they also dissolve more easily owing to their higher vapor pressure and solubility. Thus, acoustic nanodrops have required a tradeoff between vaporizability and colloidal stability in vivo. The recent advent of vaporizable endoskeletal droplets, which are both stable and vaporizable, may have solved this problem. The purpose of this review is to justify this premise by pointing out the beneficial properties of acoustic nanodrops, providing an analysis of vaporization and dissolution mechanisms, and reviewing current biomedical applications.
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Affiliation(s)
- Mark A. Borden
- Biomedical Engineering, Mechanical Engineering, University of Colorado, Boulder, USA
| | - Gazendra Shakya
- Biomedical Engineering, Mechanical Engineering, University of Colorado, Boulder, USA
| | - Awaneesh Upadhyay
- Biomedical Engineering, Mechanical Engineering, University of Colorado, Boulder, USA
| | - Kang-Ho Song
- Biomedical Engineering, Mechanical Engineering, University of Colorado, Boulder, USA
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Encarnación Escobar JM, Nieland J, van Houselt A, Zhang X, Lohse D. Marangoni puffs: dramatically enhanced dissolution of droplets with an entrapped bubble. SOFT MATTER 2020; 16:4520-4527. [PMID: 32352141 DOI: 10.1039/d0sm00093k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We present a curious effect observed during the dissolution process of water-immersed long-chain alcohol drops with an entrapped air bubble. These droplets dissolve while entrapping an air bubble pinned at the substrate. We qualitatively describe and explain four different phases that are found during the dissolution of this kind of system. The dissolution rate in the four phases differ dramatically. When the drop-water interface and the air bubble contact each other, rapid cyclic changes of the morphology are found: The breakage of the thin alcohol layer in between the bubble and the water leads to the formation of a three phase contact line. If the surface tension of the water-air interface supersedes those of the alcohol-water and alcohol-air interfaces, alcohol from the droplet is pulled upwards, leading to a closure of the air-water interface and the formation of a new thin alcohol film, which then dissolves again, leading to a repetition of the series of events. We call this sequence of events Marangoni puffing. This only happen for alcohols of appropriate surface tension. The Marangoni puffing is an intermediate state. In the final dissolution phases the Marangoni forces dramatically accelerate the dissolution rate, which then becomes one order of magnitude faster than the purely buoyancy-convective driven dissolution. Our results have bearing on various dissolution processes in multicomponent droplet systems.
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Affiliation(s)
- José M Encarnación Escobar
- Physics of Fluids Group, Max Planck Center Twente for Complex Fluid Dynamics, JM Burgers Center for Fluid Dynamics, Mesa+, Department of Science and Technology, University of Twente, Enschede 7522 NB, The Netherlands.
| | - Jaap Nieland
- Physics of Interfaces and Nanomaterials, MESA+ Institute for Nanotechnology, University of Twente, PO Box 217, 7500AE, Enschede, The Netherlands
| | - Arie van Houselt
- Physics of Interfaces and Nanomaterials, MESA+ Institute for Nanotechnology, University of Twente, PO Box 217, 7500AE, Enschede, The Netherlands
| | - Xuehua Zhang
- Department of Chemical & Materials Engineering, University of Alberta, Edmonton, Alberta, Canada.
| | - Detlef Lohse
- Physics of Fluids Group, Max Planck Center Twente for Complex Fluid Dynamics, JM Burgers Center for Fluid Dynamics, Mesa+, Department of Science and Technology, University of Twente, Enschede 7522 NB, The Netherlands.
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12
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Udoh CE, Garbin V, Cabral JT. Polymer nanocomposite capsules formed by droplet extraction: spontaneous stratification and tailored dissolution. SOFT MATTER 2019; 15:5287-5295. [PMID: 31215582 DOI: 10.1039/c9sm00708c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We report the formation of polymeric and nanocomposite capsules via droplet solvent extraction, focusing on the interplay between solvent exchange and removal, demixing and directional solidification kinetics. We investigate a model system of sodium poly(styrene sulfonate), NaPSS and silica nanoparticles in aqueous solution, whose phase behaviour is experimentally measured, and examine a series of selective extraction solvents (toluene, butyl acetate, ethyl acetate and methyl ethyl ketone), ranging from 0.04 to 11% v/v water solubility. Tuning the rate of solvent exchange is shown to provide an effective means of decoupling demixing and solidification timescales, and thereby tunes the internal microstructure of the capsule, including hollow, microporous, core-shell, and bicontinuous morphologies. In turn, these determine the capsule dissolution mechanism and kinetics, ranging from single to pulsed release profiles of nanoparticle clusters (at intermediate solubilities), to minimal dissolution (at either extremes). These findings provide facile design and assembly strategies for functional capsules with time-varying release profiles.
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Affiliation(s)
- Christiana E Udoh
- Department of Chemical Engineering, Imperial College London, London SW7 2AZ, UK.
| | - Valeria Garbin
- Department of Chemical Engineering, Imperial College London, London SW7 2AZ, UK.
| | - João T Cabral
- Department of Chemical Engineering, Imperial College London, London SW7 2AZ, UK.
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13
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Controlled addition of new liquid component into surface droplet arrays by solvent exchange. J Colloid Interface Sci 2019; 543:164-173. [DOI: 10.1016/j.jcis.2019.02.046] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Revised: 02/14/2019] [Accepted: 02/15/2019] [Indexed: 11/20/2022]
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14
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Micro-Surface and -Interfacial Tensions Measured Using the Micropipette Technique: Applications in Ultrasound-Microbubbles, Oil-Recovery, Lung-Surfactants, Nanoprecipitation, and Microfluidics. MICROMACHINES 2019; 10:mi10020105. [PMID: 30717224 PMCID: PMC6413238 DOI: 10.3390/mi10020105] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 01/23/2019] [Accepted: 01/25/2019] [Indexed: 01/08/2023]
Abstract
This review presents a series of measurements of the surface and interfacial tensions we have been able to make using the micropipette technique. These include: equilibrium tensions at the air-water surface and oil-water interface, as well as equilibrium and dynamic adsorption of water-soluble surfactants and water-insoluble and lipids. At its essence, the micropipette technique is one of capillary-action, glass-wetting, and applied pressure. A micropipette, as a parallel or tapered shaft, is mounted horizontally in a microchamber and viewed in an inverted microscope. When filled with air or oil, and inserted into an aqueous-filled chamber, the position of the surface or interface meniscus is controlled by applied micropipette pressure. The position and hence radius of curvature of the meniscus can be moved in a controlled fashion from dimensions associated with the capillary tip (~5–10 μm), to back down the micropipette that can taper out to 450 μm. All measurements are therefore actually made at the microscale. Following the Young–Laplace equation and geometry of the capillary, the surface or interfacial tension value is simply obtained from the radius of the meniscus in the tapered pipette and the applied pressure to keep it there. Motivated by Franklin’s early experiments that demonstrated molecularity and monolayer formation, we also give a brief potted-historical perspective that includes fundamental surfactancy driven by margarine, the first use of a micropipette to circuitously measure bilayer membrane tensions and free energies of formation, and its basis for revolutionising the study and applications of membrane ion-channels in Droplet Interface Bilayers. Finally, we give five examples of where our measurements have had an impact on applications in micro-surfaces and microfluidics, including gas microbubbles for ultrasound contrast; interfacial tensions for micro-oil droplets in oil recovery; surface tensions and tensions-in-the surface for natural and synthetic lung surfactants; interfacial tension in nanoprecipitation; and micro-surface tensions in microfluidics.
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Sharratt WN, Brooker A, Robles ESJ, Cabral JT. Microfluidic solvent extraction of poly(vinyl alcohol) droplets: effect of polymer structure on particle and capsule formation. SOFT MATTER 2018; 14:4453-4463. [PMID: 29697110 DOI: 10.1039/c7sm02488f] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
We investigate the formation of poly(vinyl alcohol) microparticles by the selective extraction of aqueous polymer solution droplets, templated by microfluidics and subsequently immersed in a non-solvent bath. The role of polymer molecular mass (18-105 kg mol-1), degree of hydrolysis (88-99%) and thus solubility, and initial solution concentration (0.01-10% w/w) are quantified. Monodisperse droplets with radii ranging from 50 to 500 μm were produced at a flow-focusing junction with carrier phase hexadecane and extracted into ethyl acetate. Solvent exchange and extraction result in droplet shrinkage, demixing, coarsening and phase-inversion, yielding polymer microparticles with well-defined dimensions and internal microstructure. Polymer concentration, varied from below the overlap concentration c* to above the concentrated crossover c**, as estimated by viscosity measurements, was found to have the largest impact on the final particle size and extraction timescale, while polymer mass and hydrolysis played a secondary role. These results are consistent with the observation that the average polymer concentration upon solidification greatly exceeds c**, and that the internal microparticle porosity is largely unchanged. However, reducing the initial polymer concentration to well below c* (approximately 100×) and increasing droplet size yields thin-walled (100's of nm) capsules which controllably crumple upon extraction. The symmetry of the process can be readily broken by imposing extraction conditions at an impermeable surface, yielding large, buckled, cavity morphologies. Based on these results, we establish robust design criteria for polymer capsules and particles, demonstrated here for poly(vinyl alcohol), with well-defined shape, dimensions and internal microstructure.
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Affiliation(s)
- W N Sharratt
- Department of Chemical Engineering, Imperial College London, London SW7 2AZ, UK.
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Utoft A, Kinoshita K, Bitterfield DL, Needham D. Manipulating Single Microdroplets of NaCl Solutions: Solvent Dissolution, Microcrystallization, and Crystal Morphology. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:3626-3641. [PMID: 29510057 DOI: 10.1021/acs.langmuir.7b03977] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
A new "three-micropipette manipulation technique" for forming, dehydrating, crystallizing, and resolvating nanograms of salt material has been developed to study supersaturated single microdroplets and microcrystals. This is the first report of studies that have measured in situ both supersaturation (as homogeneous nucleation) and saturation (as microcrystal redissolution) for single microdroplets of NaCl solution using the micropipette technique. This work reports a measure of the critical supersaturation concentration for homogeneous nucleation of NaCl (10.3 ± 0.3 M) at a supersaturation fraction of S = 1.9, the saturation concentration of NaCl in aqueous solution as measured with nanograms of material (5.5 ± 0.1 M), the diffusion coefficient for water in octanol, D = (1.96 ± 0.10) × 10-6 cm2/s, and the effect of the solvent's activity on dissolution kinetics. It is further shown that the same Epstein-Plesset (EP) model, which was originally developed for diffusion-controlled dissolution and uptake of gas, and successfully applied to liquid-in-liquid dissolution, can now also be applied to describe the diffusion-controlled uptake of water from a water-saturated environment using the extended activity-based model of Bitterfield et al. This aspect of the EP model has not previously been tested using single microdroplets. Finally, it is also reported how the water dissolution rate, rate of NaCl concentration change, resulting crystal structure, and the time frame of initial crystal growth are affected by changing the bathing medium from octanol to decane. A much slower loss of water-solvent and concomitant slower up-concentration of the NaCl solute resulted in a lower tendency to nucleate and slower crystal growth because much less excess material was available at the onset of nucleation in the decane system as compared to the octanol system. Thus, the crystal structure is reported to be dendritic for NaCl solution microdroplets dissolving rapidly and nucleating violently in octanol, while they are formed as single cubic crystals in a gentler way for solution-dissolution in decane. These new techniques and analyses can now also be used for any other system where all relevant parameters are known. An example of this is control of drug/hydrogel/emulsion particle size change due to solvent uptake.
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Affiliation(s)
- Anders Utoft
- Center for Single Particle Science and Engineering (SPSE), Health Sciences , University of Southern Denmark , Odense 5230 , Denmark
| | - Koji Kinoshita
- Center for Single Particle Science and Engineering (SPSE), Health Sciences , University of Southern Denmark , Odense 5230 , Denmark
| | | | - David Needham
- Center for Single Particle Science and Engineering (SPSE), Health Sciences , University of Southern Denmark , Odense 5230 , Denmark
- Department of Mechanical Engineering and Materials Science , Duke University , Durham , North Carolina 27708 , United States
- School of Pharmacy , University of Nottingham , Nottingham NG7 2RD , United Kingdom
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Lamorgese A, Mauri R. Dissolution or Growth of a Liquid Drop via Phase-Field Ternary Mixture Model Based on the Non-Random, Two-Liquid Equation. ENTROPY 2018; 20:e20020125. [PMID: 33265216 PMCID: PMC7512619 DOI: 10.3390/e20020125] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 02/06/2018] [Accepted: 02/11/2018] [Indexed: 11/16/2022]
Abstract
We simulate the diffusion-driven dissolution or growth of a single-component liquid drop embedded in a continuous phase of a binary liquid. Our theoretical approach follows a diffuse-interface model of partially miscible ternary liquid mixtures that incorporates the non-random, two-liquid (NRTL) equation as a submodel for the enthalpic (so-called excess) component of the Gibbs energy of mixing, while its nonlocal part is represented based on a square-gradient (Cahn-Hilliard-type modeling) assumption. The governing equations for this phase-field ternary mixture model are simulated in 2D, showing that, for a single-component drop embedded in a continuous phase of a binary liquid (which is highly miscible with either one component of the continuous phase but is essentially immiscible with the other), the size of the drop can either shrink to zero or reach a stationary value, depending on whether the global composition of the mixture is within the one-phase region or the unstable range of the phase diagram.
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Lamorgese A, Mauri R. Diffusion-Driven Dissolution or Growth of a Liquid Drop Embedded in a Continuous Phase of Another Liquid via Phase-Field Ternary Mixture Model. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:13125-13132. [PMID: 28981279 DOI: 10.1021/acs.langmuir.7b02105] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We simulate the diffusion-driven dissolution or growth of a single-component (resp. two-component) drop embedded in a continuous phase of a binary (resp. single-component) liquid. Our theoretical approach follows a standard diffuse-interface model of partially miscible ternary liquid mixtures, which is based on a regular solution model assumption together with a Flory-Huggins and Cahn-Hilliard representation of the excess and nonlocal components of the Gibbs free energy of mixing. Based on 2D simulation results, we show that for a single-component drop embedded in a continuous phase of a binary liquid (which is highly miscible with either one component of the continuous phase but essentially immiscible with the other) the size of the drop can either shrink to zero or reach a stationary value, depending on whether the global composition of the mixture is within the one-phase region or the unstable range of the phase diagram. On the other hand, for an isolated two-component drop embedded in a continuous phase of a single-component liquid (which is essentially immiscible with either one component of the drop but miscible with the other) the size of the drop can either grow or shrink and, in particular, it will eventually go to zero if the global composition of the mixture is within the one-phase region; otherwise, for system locations in the unstable range the size of the drop tends to a constant value as the composition within the drop reaches its final equilibrium value.
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Affiliation(s)
- Andrea Lamorgese
- Department of Civil and Industrial Engineering/Chemical Engineering Section, Laboratory of Multiphase Reactive Flows, University of Pisa , Largo Lazzarino 1, 56122 Pisa, Italy
| | - Roberto Mauri
- Department of Civil and Industrial Engineering/Chemical Engineering Section, Laboratory of Multiphase Reactive Flows, University of Pisa , Largo Lazzarino 1, 56122 Pisa, Italy
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Parra E, Hervella P, Needham D. Real-Time Visualization of the Precipitation and Phase Behavior of Octaethylporphyrin in Lipid Microparticles. J Pharm Sci 2016; 106:1025-1041. [PMID: 27956095 DOI: 10.1016/j.xphs.2016.11.019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2016] [Accepted: 11/29/2016] [Indexed: 11/30/2022]
Abstract
The material properties of micro- and nanoparticles are fundamental for their bulk properties in suspension, like their stability and encapsulation efficiency. A particularly interesting system with potential biomedical applications is the encapsulation of hydrophobic porphyrins into lipid particles and their use as metal atom chelators, where retention and stability are keys for the design process. The overall goal here was to study the solubility, phase behavior, and mixing of octaethylporphyrin (OEP) and OEP-Cu chelates with 2 core materials, triolein (TO) and cholesteryl acetate, as single microparticles. We employed a real-time, single-particle microscopic technique based on micropipette injection to characterize the behavior of these materials and their mixtures upon solvent loss and precipitation. A clear phase separation was observed between the triolein liquid core and porphyrin microcrystals, and the ternary phase diagram of the droplet compositions and onsets of phase separation over solvent dissolution was built. On the contrary, cholesteryl acetate and OEP-Cu coprecipitated by solvent dissolution, preventing porphyrin crystallization even for very high supersaturations. This type of real-time, single-particle characterization is expected to offer important information about the formulation of other hydrophobic compounds of interest, where finding the proper encapsulation environment is a key step for their retention and stability.
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Affiliation(s)
- Elisa Parra
- Center for Single Particle Science and Engineering, University of Southern Denmark, Odense, Denmark.
| | - Pablo Hervella
- Center for Single Particle Science and Engineering, University of Southern Denmark, Odense, Denmark
| | - David Needham
- Center for Single Particle Science and Engineering, University of Southern Denmark, Odense, Denmark; Department of Mechanical Engineering and Material Science, Duke University, Durham, North Carolina 27708
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Bitterfield DL, Utoft A, Needham D. An Activity-Based Dissolution Model for Solute-Containing Microdroplets. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:12749-12759. [PMID: 27802055 DOI: 10.1021/acs.langmuir.6b03126] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
When a solute is present in an aqueous droplet, the water activity in the droplet and the rate of droplet dissolution are both decreased (as compared to a pure water droplet). One of the main parameters that controls this effect is the dynamically changing solute concentration, and therefore water activity and chemical potential, at the droplet interface. This work addresses the importance of understanding how water activity changes during solution droplet dissolution. A model for dissolution rate is presented that accounts for the kinetic effects of changing water activity at the droplet interface during the dissolution of an aqueous salt solution microdroplet into a second immiscible liquid phase. The important underlying question in this model is whether the dissolving component can be considered in local equilibrium on both sides of the droplet interface and whether this assumption is sufficient to account for the kinetics of dissolution. The dissolution model is based on the Epstein-Plesset equation, which has previously been applied to pure gas (bubble) and liquid (droplet) dissolution into liquid phases, but not to salt solutions. The model is tested by using the micropipet technique to form and observe the dehydration of single NaCl solution microdroplets in octanol or butyl acetate. The model successfully predicts the droplet diameter as a function of time in both organic solvents. The NaCl concentration in water is measured well into the supersaturated area >5.4 M, and the supersaturation limit at which NaCl nucleation happens is reported to be 10.24 ± 0.31 M.
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Affiliation(s)
- Deborah L Bitterfield
- Department of Mechanical Engineering and Materials Science, Duke University , Durham, North Carolina 27708, United States
| | - Anders Utoft
- Center for Single Particle Science and Engineering (SPSE), University of Southern Denmark , Odense, Denmark
| | - David Needham
- Department of Mechanical Engineering and Materials Science, Duke University , Durham, North Carolina 27708, United States
- Center for Single Particle Science and Engineering (SPSE), University of Southern Denmark , Odense, Denmark
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From Single Microparticles to Microfluidic Emulsification: Fundamental Properties (Solubility, Density, Phase Separation) from Micropipette Manipulation of Solvent, Drug and Polymer Microspheres. Processes (Basel) 2016. [DOI: 10.3390/pr4040049] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Mountford PA, Borden MA. On the thermodynamics and kinetics of superheated fluorocarbon phase-change agents. Adv Colloid Interface Sci 2016; 237:15-27. [PMID: 27574721 DOI: 10.1016/j.cis.2016.08.007] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2016] [Revised: 08/08/2016] [Accepted: 08/12/2016] [Indexed: 11/24/2022]
Abstract
Superheated nanodrops are a new class of submicron-diameter liquid emulsion particles comprising perfluoropropane (C3F8), perfluorobutane (C4F10) and perfluoropentane (C5F12) that are being developed for ultrasound imaging and therapy. They can be formed by condensation of precursor lipid-coated, gas-filled microbubbles. Application of ultrasound or laser energy triggers the phase transformation back to a vapor bubble, and this process can be exploited for certain biomedical applications. The nanodrops are remarkably metastable in the liquid state under physiological conditions, even though they are highly superheated. In prior work, it was suggested that a high Laplace pressure in the lipid-coated nanodrop is responsible for its stability in the superheated state. Recent work by our group, however, points to the energy barrier for homogeneous nucleation as a more likely explanation. The purpose of this article is to review and discuss this mechanism in greater detail. We start with a brief description of basic fluorocarbon intermolecular forces. We then use the van der Waals equation of state to construct equilibrium phase diagrams and saturation curves. The effect of droplet Laplace pressure is superimposed onto these curves and compared to experimental data, where a poor correlation is observed. It is also shown that nanodrops with Laplace pressure are unstable to dissolution. The mechanism of homogeneous nucleation is then offered as an alternative explanation for the metastability of superheated nanodrops, with calculations that show good agreement with experimental data.
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New sensitive micro-measurements of dynamic surface tension and diffusion coefficients: Validated and tested for the adsorption of 1-Octanol at a microscopic air-water interface and its dissolution into water. J Colloid Interface Sci 2016; 488:166-179. [PMID: 27825061 DOI: 10.1016/j.jcis.2016.10.052] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Revised: 10/18/2016] [Accepted: 10/19/2016] [Indexed: 11/23/2022]
Abstract
Currently available dynamic surface tension (DST) measurement methods, such as Wilhelmy plate, droplet- or bubble-based methods, still have various experimental limitations such as the large size of the interface, convection in the solution, or a certain "dead time" at initial measurement. These limitations create inconsistencies for the kinetic analysis of surfactant adsorption/desorption, especially significant for ionic surfactants. Here, the "micropipette interfacial area-expansion method" was introduced and validated as a new DST measurement having a high enough sensitivity to detect diffusion controlled molecular adsorption at the air-water interfaces. To validate the new technique, the diffusion coefficient of 1-Octanol in water was investigated with existing models: the Ward Tordai model for the long time adsorption regime (1-100s), and the Langmuir and Frumkin adsorption isotherm models for surface excess concentration. We found that the measured diffusion coefficient of 1-Octanol, 7.2±0.8×10-6cm2/s, showed excellent agreement with the result from an alternative method, "single microdroplet catching method", to measure the diffusion coefficient from diffusion-controlled microdroplet dissolution, 7.3±0.1×10-6cm2/s. These new techniques for determining adsorption and diffusion coefficients can apply for a range of surface active molecules, especially the less-characterized ionic surfactants, and biological compounds such as lipids, peptides, and proteins.
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Needham D, Arslanagic A, Glud K, Hervella P, Karimi L, Høeilund-Carlsen PF, Kinoshita K, Mollenhauer J, Parra E, Utoft A, Walke P. Bottom up design of nanoparticles for anti-cancer diapeutics: “put the drug in the cancer’s food”. J Drug Target 2016; 24:836-856. [DOI: 10.1080/1061186x.2016.1238092] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- David Needham
- Department of Mechanical Engineering and Material Science, Duke University, Durham, NC, USA
- Center for Single Particle Science and Engineering (SPSE), University of Southern Denmark, Odense, Denmark
| | - Amina Arslanagic
- Center for Single Particle Science and Engineering (SPSE), University of Southern Denmark, Odense, Denmark
| | - Kasper Glud
- Center for Single Particle Science and Engineering (SPSE), University of Southern Denmark, Odense, Denmark
| | - Pablo Hervella
- Center for Single Particle Science and Engineering (SPSE), University of Southern Denmark, Odense, Denmark
| | - Leena Karimi
- Center for Single Particle Science and Engineering (SPSE), University of Southern Denmark, Odense, Denmark
| | | | - Koji Kinoshita
- Center for Single Particle Science and Engineering (SPSE), University of Southern Denmark, Odense, Denmark
| | - Jan Mollenhauer
- NanoCAN, Institute for Molecular Medicine (IMM), SUND, University of Southern Denmark, Odense, Denmark
| | - Elisa Parra
- Center for Single Particle Science and Engineering (SPSE), University of Southern Denmark, Odense, Denmark
| | - Anders Utoft
- Center for Single Particle Science and Engineering (SPSE), University of Southern Denmark, Odense, Denmark
| | - Prasad Walke
- Center for Single Particle Science and Engineering (SPSE), University of Southern Denmark, Odense, Denmark
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Song Y, Lu Z, Yang H, Zhang S, Zhang X. Dissolution of Sessile Microdroplets of Electrolyte and Graphene Oxide Solutions in an Ouzo System. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:10296-10304. [PMID: 27627218 DOI: 10.1021/acs.langmuir.6b02837] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Manipulating the way a droplet shrinks by evaporation or dissolution is an effective approach for assembling dissolved nanomaterials. In this work, we investigate the dissolution dynamics of a submicroliter sessile droplet of electrolyte aqueous solution and of graphene oxide suspension immersed in a binary mixture of solvents, among which one is miscible and the other is immiscible with water (i.e., an Ouzo system). Our measurements reveal an interesting two-stage dissolution of the droplet: a fast initial stage and a slow second stage. The duration of the first stage is longer at a lower temperature, leading to a counterintuitive result that the dissolution completes faster at reduced temperature. The presence of graphene oxide in the droplet dramatically alters the dissolution dynamics, possibly due to its enrichment at the droplet surface. The finding from this work provides useful guideline for designing conditions to pack nanomaterials by dissolving droplets, especially for those temperature sensitive components.
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Affiliation(s)
- Yuting Song
- Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences , Chengdu 610041, China
- Institute of Processing Engineering, Chinese Academy of Sciences , Beijing 100190, China
- University of Chinese Academy of Sciences, Chinese Academy of Sciences , Beijing 100190, P. R. China
| | - Ziyang Lu
- Soft Matter & Interfaces Group, School of Engineering, RMIT University , Melbourne, Victoria 3001, Australia
| | - Haijun Yang
- Shanghai Institute of Applied Science, Chinese Academy of Sciences , Shanghai100190, China
| | - Suojiang Zhang
- Institute of Processing Engineering, Chinese Academy of Sciences , Beijing 100190, China
| | - Xuehua Zhang
- Soft Matter & Interfaces Group, School of Engineering, RMIT University , Melbourne, Victoria 3001, Australia
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Mustafa A, Erten A, Ayaz RMA, Kayıllıoğlu O, Eser A, Eryürek M, Irfan M, Muradoglu M, Tanyeri M, Kiraz A. Enhanced Dissolution of Liquid Microdroplets in the Extensional Creeping Flow of a Hydrodynamic Trap. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:9460-9467. [PMID: 27571341 DOI: 10.1021/acs.langmuir.6b02411] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
A novel noncontact technique based on hydrodynamic trapping is presented to study the dissolution of freely suspended liquid microdroplets into a second immiscible phase in a simple extensional creeping flow. Benzyl benzoate (BB) and n-decanol microdroplets are individually trapped at the stagnation point of a planar extensional flow, and dissolution of single microdroplets into an aqueous solution containing surfactant is characterized at different flow rates. The experimental dissolution curves are compared to two models: (i) the Epstein-Plesset (EP) model which considers only diffusive mass transfer, and (ii) the Zhang-Yang-Mao (ZYM) model which considers both diffusive and convective mass transfer in the presence of extensional creeping flow. The EP model significantly underpredicts the experimentally determined dissolution rates for all experiments. In contrast, very good agreement is observed between the experimental dissolution curves and the ZYM model when the saturation concentration of the microdroplet liquid (cs) is used as the only fitting parameter. Experiments with BB microdroplets at low surfactant concentration (10 μM) reveal cs values very similar to that reported in the literature. In contrast, experiments with BB and n-decanol microdroplets at 10 mM surfactant concentration, higher than the critical micelle concentration (CMC) of 5 mM, show further enhancements in microdroplet dissolution rates due to micellar solubilization. The presented method accurately tests the dissolution of single microdroplets into a second immiscible phase in extensional creeping flow and has potential for applications such as separation processes, food dispersion, and drug development/design.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Melikhan Tanyeri
- Department of Electrical and Electronics Engineering, Istanbul Sehir University , 34662 Uskudar, Istanbul Turkey
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Mountford PA, Smith WS, Borden MA. Fluorocarbon nanodrops as acoustic temperature probes. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2015; 31:10656-10663. [PMID: 26359919 DOI: 10.1021/acs.langmuir.5b02308] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
This work investigated the use of superheated fluorocarbon nanodrops for ultrasound thermal imaging and the use of mixed fluorocarbons for tuning thermal and acoustic thresholds for vaporization. Droplets were fabricated by condensing phospholipid-coated microbubbles containing C3F8 and C4F10 mixed at various molar ratios. Vaporization temperatures first were measured in a closed system by optical transmission following either isothermal pressure release or isobaric heating. The vaporization temperature was found to depend linearly on the percentage of C4F10 in the droplet core, indicating excellent tunability under these fluorocarbon-saturated conditions. Vaporization temperatures were then measured in an open system using contrast-enhanced ultrasound imaging, where it was found that the mixed droplets behaved like pure C4F10 drops. Additionally, the critical mechanical index for vaporization was measured at the limits of therapeutic hyperthermia (37 and 60 °C), and again the mixed droplets were found to behave like pure C4F10 drops. These results suggested that C3F8 preferentially dissolves out of the droplet core in open systems, as shown by a simple mass transfer model of multicomponent droplet dissolution. Finally, proof-of-concept was shown that pure C4F10 nanodrops can be used as an acoustic temperature probe. Overall, these results not only demonstrate the potential of superheated fluorocarbon emulsions for sonothermetry but also point to the limits of tunability for fluorocarbon mixtures owing to preferential release of the more soluble species to the atmosphere.
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Affiliation(s)
- Paul A Mountford
- Department of Mechanical Engineering, University of Colorado , Boulder, Colorado 80309, United States
| | - William S Smith
- Department of Mechanical Engineering, University of Colorado , Boulder, Colorado 80309, United States
| | - Mark A Borden
- Department of Mechanical Engineering, University of Colorado , Boulder, Colorado 80309, United States
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