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Gupta S, Varanakkottu SN, Mani E, Satapathy DK. Contact Angle Modulation: In Situ Polymer Deposition during Sessile Drop Evaporation. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2024; 40:12594-12601. [PMID: 38837177 DOI: 10.1021/acs.langmuir.4c01039] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2024]
Abstract
The drying kinetics of a sessile drop on a solid surface are a widely studied phenomenon because of their relevance to various fields such as coating, printing, medical diagnostics, sensing, and microfluidic technology. Typically, the drop undergoes drying either at a constant contact radius (R) with a decrease in the three-phase contact angle or at a constant contact angle (θ) with a reduction in the radius with time. These two drying modes are referred to as CCR and CCA, respectively. It is not uncommon where both R and θ may decrease during drying, especially in the penultimate stage of drying. In this work, we report a scenario wherein the θ increases while R decreases during the drying process of an aqueous polymer solution on a high surface energy substrate. This behavior is observed across different polymer systems (such as poly(ethylene oxide) and polyvinyl pyrrolidine), varying molecular weights, and polymer concentrations. As the drop dries, the polymer gets deposited at the three-phase contact line, thus reducing the surface energy of the substrate and leading to an increase in the contact angle. The drop responds by attempting to reach a new equilibrium contact angle through slipping. The temporal increase in contact angle follows a power law scaling behavior. This study demonstrates an in situ modulation of contact angle facilitated by evaporation and polymer deposition, showcasing unconventional drying dynamics.
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Affiliation(s)
- Shakshi Gupta
- Soft Material Laboratory, Department of Physics, IIT Madras, Chennai 600036, India
- Centre for Soft and Biological Matter, IIT Madras, Chennai 600036, India
| | | | - Ethayaraja Mani
- Department of Chemical Engineering, IIT Madras, Chennai 600036, India
- Centre for Soft and Biological Matter, IIT Madras, Chennai 600036, India
| | - Dillip K Satapathy
- Soft Material Laboratory, Department of Physics, IIT Madras, Chennai 600036, India
- Centre for Soft and Biological Matter, IIT Madras, Chennai 600036, India
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Al-Litani K, Ali T, Robles Martinez P, Buanz A. 3D printed implantable drug delivery devices for women's health: Formulation challenges and regulatory perspective. Adv Drug Deliv Rev 2023; 198:114859. [PMID: 37149039 DOI: 10.1016/j.addr.2023.114859] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2023] [Revised: 04/03/2023] [Accepted: 04/29/2023] [Indexed: 05/08/2023]
Abstract
Modern pharmaceutical interventions are shifting from traditional "one-size-fits-all" approaches toward tailored therapies. Following the regulatory approval of Spritam®, the first marketed drug manufactured using three-dimensional printing (3DP) technologies, there is a precedence set for the use of 3DP in the manufacture of pharmaceutical products. The involvement of 3DP technologies in pharmaceutical research has demonstrated its capabilities in enabling the customisation of characteristics such as drug dosing, release characteristics and product designs on an individualised basis. Nonetheless, research into 3DP implantable drug delivery devices lags behind that for oral devices, cell-based therapies and tissue engineering applications. The recent efforts and initiatives to address the disparity in women's health is overdue but should provide a drive for more research into this area, especially using new and emerging technologies as 3DP. Therefore, the focus of this review has been placed on the unique opportunity of formulating personalised implantable drug delivery systems using 3DP for women's health applications, particularly passive implants. An evaluation of the current landscape and key formulation challenges for achieving this is provided supplemented with critical insight into the current global regulatory status and its outlook.
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Affiliation(s)
- Karen Al-Litani
- UCL School of Pharmacy, University College London, WC1N 1AX, London, UK
| | - Tariq Ali
- UCL School of Pharmacy, University College London, WC1N 1AX, London, UK; Department of Pharmaceutics, Faculty of Pharmaceutical Sciences, Dow University of Health Sciences, Karachi, Pakistan
| | | | - Asma Buanz
- UCL School of Pharmacy, University College London, WC1N 1AX, London, UK; School of Science, Faculty of Engineering and Science, University of Greenwich, ME4 4TB, UK.
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Effect of Corrosion and Wall Textures on Wettability and Heat Flux at Non-Isothermal Conditions. COATINGS 2021. [DOI: 10.3390/coatings12010046] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The corrosion behavior, evaporation and heat transfer of aluminum alloy during droplet evaporation of an aggressive solution of NaCl and hydrogen peroxide in water have been studied experimentally. To date, the effect of corrosion on the evaporation and heat transfer of droplet salt solutions on textured surfaces remains insufficiently explored. The corrosion resistance of the material and the contact angle increase with an increase in the number of laser penetrations after laser texturing. Studies conducted using an electron microscope and Energy-Dispersive X-ray Spectroscopy (EDS) mapping show that the maximum amount of adsorbed hydrocarbon impurities falls on areas with a large number of pits. In the process of metal corrosion, wettability and heat transfer change. In spite of the fact that laser exposure significantly increases the corrosion resistance, the wettability of the wall changes significantly due to corrosion. The wetted diameter of a droplet changes over time, which leads to an increase in the evaporation rate and heat flux. The heat flux during evaporation of a droplet on a heated wall depends on the water droplet diameter, the texture of the wall and the corrosion resistance.
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McBride SA, Skye R, Varanasi KK. Differences between Colloidal and Crystalline Evaporative Deposits. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:11732-11741. [PMID: 32937070 DOI: 10.1021/acs.langmuir.0c01139] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Evaporative deposits from drops are widely studied due to their numerous applications in low-effort self-assembly, including for inkjet printing, microscale separations, and sensing/diagnostics. This phenomenon has been broadly explored for drops containing suspended colloidal particles but has been less quantified for drops with dissolved solutes. When a drop of solute/solvent mixture is evaporated on a substrate, nonvolatile solutes become supersaturated as the solvent evaporates, which then leads to crystal nucleation at the substrate-drop contact line. Emerging crystals alter the local wettability and fundamentally alter the dynamics of evaporation, which, in turn, influences the resultant evaporative deposit. Here we investigate the role of interactions between the substrate, crystals, and solution by comparing the evaporative deposition of three different salts as solutes against an evaporating colloidal solution. We show that nucleation effects can cause crystalline deposits to have a temperature relationship that is opposite to that of colloidal deposits and demonstrate how a balance between the contact-line pinning force and nucleation controls the deposit size.
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Affiliation(s)
- Samantha A McBride
- Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Rachael Skye
- Department of Materials Science Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Kripa K Varanasi
- Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
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McBride SA, Dash S, Khan S, Varanasi KK. Evaporative Crystallization of Spirals. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:10484-10490. [PMID: 31260320 DOI: 10.1021/acs.langmuir.9b01002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Spiral motifs are pervasive in nature, art, and technology due to their functional property of providing compact length. Nature is particularly adept at spiral patterning, and yet, the spirals observed in seashells, hurricanes, rams' horns, flower petals, etc. all evolve via disparate physical mechanisms. Here, we present a mechanism for the self-guided formation of spirals from evaporating saline drops via a coupling of crystallization and contact line dynamics. These patterns are in contrast to commonly observed patterns from evaporation of colloidal drops, which are discrete (rings, concentric rings) or continuous (clumps, uniform deposits) depending on the particle shape, contact line dynamics, and evaporation rate. Unlike the typical process of drop evaporation where the contact line moves radially inward, here, a thin film pinned by a ring of crystals ruptures radially outward. This motion is accompanied by a nonuniform pinning of the contact line due to crystallization, which generates a continuous propagation of pinning and depinning events to form a spiral. By comparing the relevant timescales of evaporation and diffusion, we show that a single dimensionless number can predict the occurrence of these patterns. These insights on self-guided crystallization of spirals could be used to create compact length templates.
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Affiliation(s)
- Samantha A McBride
- Department of Mechanical Engineering , Massachusetts Institute of Technology , 77 Massachusetts Avenue , Cambridge , Massachusetts 02139 , United States
| | - Susmita Dash
- Department of Mechanical Engineering , Indian Institute of Science , CV Raman Road , Bengaluru 560012 , India
| | - Sami Khan
- Department of Mechanical Engineering , Massachusetts Institute of Technology , 77 Massachusetts Avenue , Cambridge , Massachusetts 02139 , United States
| | - Kripa K Varanasi
- Department of Mechanical Engineering , Massachusetts Institute of Technology , 77 Massachusetts Avenue , Cambridge , Massachusetts 02139 , United States
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Kita Y, Okauchi Y, Fukatani Y, Orejon D, Kohno M, Takata Y, Sefiane K. Quantifying vapor transfer into evaporating ethanol drops in a humid atmosphere. Phys Chem Chem Phys 2018; 20:19430-19440. [DOI: 10.1039/c8cp02521e] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
A simultaneous evaporation and water intake empirical model for evaporation of organic solvent ethanol drops.
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Affiliation(s)
- Yutaku Kita
- International Institute for Carbon-Neutral Energy Research (WPI-I2CNER)
- Kyushu University
- Fukuoka 819-0395
- Japan
- Department of Mechanical Engineering
| | - Yuya Okauchi
- Department of Mechanical Engineering
- Thermofluid Physics Laboratory
- Kyushu University
- Fukuoka 819-0395
- Japan
| | | | - Daniel Orejon
- International Institute for Carbon-Neutral Energy Research (WPI-I2CNER)
- Kyushu University
- Fukuoka 819-0395
- Japan
- Department of Mechanical Engineering
| | - Masamichi Kohno
- Department of Mechanical Engineering
- Thermofluid Physics Laboratory
- Kyushu University
- Fukuoka 819-0395
- Japan
| | - Yasuyuki Takata
- International Institute for Carbon-Neutral Energy Research (WPI-I2CNER)
- Kyushu University
- Fukuoka 819-0395
- Japan
- Department of Mechanical Engineering
| | - Khellil Sefiane
- Institue of Multiscale Thermofluids
- School of Engineering
- The University of Edinburgh
- King's Buildings
- Edinburgh EH9 3JL
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A New Label-Free Technique for Analysing Evaporation Induced Self-Assembly of Viral Nanoparticles Based on Enhanced Dark-Field Optical Imaging. NANOMATERIALS 2017; 8:nano8010001. [PMID: 29271875 PMCID: PMC5791088 DOI: 10.3390/nano8010001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/22/2017] [Revised: 11/29/2017] [Accepted: 12/12/2017] [Indexed: 12/21/2022]
Abstract
Nanoparticle self-assembly is a complex phenomenon, the control of which is complicated by the lack of appropriate tools and techniques for monitoring the phenomenon with adequate resolution in real-time. In this work, a label-free technique based on dark-field microscopy was developed to investigate the self-assembly of nanoparticles. A bio-nanoparticle with complex shape (T4 bacteriophage) that self-assembles on glass substrates upon drying was developed. The fluid flow regime during the drying process, as well as the final self-assembled structures, were studied using dark-field microscopy, while phage diffusion was analysed by tracking of the phage nanoparticles in the bulk solutions. The concentrations of T4 phage nanoparticles and salt ions were identified as the main parameters influencing the fluid flow, particle motion and, consequently, the resulting self-assembled structure. This work demonstrates the utility of enhanced dark-field microscopy as a label-free technique for the observation of drying-induced self-assembly of bacteriophage T4. This technique provides the ability to track the nano-sized particles in different matrices and serves as a strong tool for monitoring self-assembled structures and bottom-up assembly of nano-sized building blocks in real-time.
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Orejon D, Shanahan MER, Takata Y, Sefiane K. Kinetics of Evaporation of Pinned Nanofluid Volatile Droplets at Subatmospheric Pressures. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:5812-5820. [PMID: 27218303 DOI: 10.1021/acs.langmuir.6b00753] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We examine the effects of nanoparticle addition at low concentration on the evaporation kinetics of droplets in the constant radius mode. The evaporative behavior of deionized water and Al2O3 nanoparticle laden water on an aluminum substrate was observed at atmospheric and at different subatmospheric pressures. The two fluids exhibit the same evaporative behavior, independent of the droplet volume or the subatmospheric pressure. Moreover, the linear relationship between evaporation rate and droplet radius, initially proposed by Picknett and Bexon nearly four decades ago for droplets evaporating in the constant radius mode, is satisfied for both liquids. In addition, we have established a unified correlation solely function of fluid properties that extends this relationship to any subatmospheric pressure and fluid tested. We conclude that the addition of a small quantity of nanoparticles to the base fluid does not modify the kinetics of evaporation for pinned volatile droplets.
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Affiliation(s)
- Daniel Orejon
- School of Engineering, The University of Edinburgh , King's Buildings, Mayfield Road, Edinburgh EH9 3JL, United Kingdom
| | - Martin E R Shanahan
- University of Bordeaux, I2M, UMR 5295, F-33400 Talence, France
- CNRS, I2M, UMR 5295, F-33400 Talence, France
- Arts et Metiers ParisTech, I2M, UMR 5295, F-33400 Talence, France
| | | | - Khellil Sefiane
- School of Engineering, The University of Edinburgh , King's Buildings, Mayfield Road, Edinburgh EH9 3JL, United Kingdom
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Msambwa Y, Shackleford ASD, Ouali FF, Fairhurst DJ. Controlling and characterising the deposits from polymer droplets containing microparticles and salt. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2016; 39:21. [PMID: 26920524 DOI: 10.1140/epje/i2016-16021-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Accepted: 02/02/2016] [Indexed: 06/05/2023]
Abstract
A coffee ring-stain is left behind when droplets containing a wide range of different suspended particles evaporate, caused by a pinned contact line generating a strong outwards capillary flow. Conversely, in the very peculiar case of evaporating droplets of poly(ethylene oxide) solutions, tall pillars are deposited in the centre of the droplet following a boot-strapping process in which the contact line recedes quickly, driven by a constricting collar of polymer crystallisation: no other polymer has been reported to produce these central pillars. Here we map out the phase behaviour seen when the specific pillar-forming polymer is combined with spherical microparticles, illustrating a range of final deposit shapes, including the standard particle ring-stain, polymer pillars and also flat deposits. The topologies of the deposits are measured using profile images and stylus profilometery, and characterised using the skewness of the profile as a simple analytic method for quantifying the shapes: pillars produce positive skew, flat deposits have zero skew and ring-stains have a negative value. We also demonstrate that pillar formation is even more effectively disrupted using potassium sulphate salt solutions, which change the water from a good solvent to a theta-point solvent, consequently reducing the size and configuration of the polymer coils. This inhibits polymer crystallisation, interfering with the bootstrap process and ultimately prevents pillars from forming. Again, the deposit shapes are quantified using the skew parameter.
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Affiliation(s)
- Y Msambwa
- Nottingham Trent University, Clifton Lane, NG11 8NS, Nottingham, UK
| | | | - F F Ouali
- Nottingham Trent University, Clifton Lane, NG11 8NS, Nottingham, UK
| | - D J Fairhurst
- Nottingham Trent University, Clifton Lane, NG11 8NS, Nottingham, UK.
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