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Yuan H, Chao Y, Shum HC. Droplet and Microchamber-Based Digital Loop-Mediated Isothermal Amplification (dLAMP). SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2020; 16:e1904469. [PMID: 31899592 DOI: 10.1002/smll.201904469] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2019] [Revised: 10/22/2019] [Indexed: 05/15/2023]
Abstract
Digital loop-mediated isothermal amplification (dLAMP) refers to compartmentalizing nucleic acids and LAMP reagents into a large number of individual partitions, such as microchambers and droplets. This compartmentalization enables dLAMP to be an excellent platform to quantify the absolute number of the target nucleic acids. Owing to its low requirement for instrumentation complexity, high specificity, and strong tolerance to inhibitors in the nucleic acid samples, dLAMP has been recognized as a simple and accurate technique to quantify pathogenic nucleic acid. Herein, the general process of dLAMP techniques is summarized, the current dLAMP techniques are categorized, and a comprehensive discussion on different types of dLAMP techniques is presented. Also, the challenges of the current dLAMP are illustrated together with the possible strategies to address these challenges. In the end, the future directions of the dLAMP developments, including multitarget detection, multisample detection, and processing nucleic acid extraction are outlined. With recently significant advances in dLAMP, this technology has the potential to see more widespread use beyond the laboratory in the future.
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Kong T, Shum HC, Weitz DA. The Fourth Decade of Microfluidics. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2020; 16:e2000070. [PMID: 32133792 DOI: 10.1002/smll.202000070] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
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Lu Y, Chan YK, Lau LH, Wong D, Wong JKW, Shih KC, Lai SM, Shum HC. Amphiphilic additives in silicone oil tamponade and emulsification: an eye-on-a-chip study. Acta Ophthalmol 2020; 98:e232-e237. [PMID: 31386804 DOI: 10.1111/aos.14212] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Accepted: 07/10/2019] [Indexed: 12/26/2022]
Abstract
AIMS Recently, chemically modified silicone oil has been demonstrated as a reservoir for sustained release of intraocular drugs, many of which might be amphiphilic in nature. In this work, we study the effect of amphiphilic additives in silicone oil on emulsification under eye-like movements. METHODS Three silicone-oil-soluble surfactants, namely DC749, MQ1640 and FZ2233, were used as model amphiphilic additives. The change of viscosity was measured by a rheometer in the cone-and-plate geometry. The interfacial tension (IFT) between silicone oil and model aqueous phase was measured by pendant drop tensiometry. Emulsification of silicone oil was induced by simulated saccadic eye movements on a cell-coated eye-on-a-chip platform for 4 days. The number of emulsified silicone oil droplets observed in the aqueous phase was assessed daily by optical microscopy. RESULTS Significantly more emulsified droplets were formed in silicone oil with DC749 or MQ1640 (P < 0.05). However, such increase was not directly related to the change in IFT nor viscosity. Moreover, water droplets were also found in the silicone oil, but not in the control silicone oil without additive. CONCLUSIONS The amphiphilic substances in silicone oil promoted emulsification. Besides typical oil-in-water drops that normally affect the eye, water-in-oil drops were also formed. Before silicone oil could be considered as a vehicle for drug delivery, the nature of the drug and its possible effect on emulsification and therefore on the pharmacokinetics needs to be investigated. An additional concern is that water-in-oil droplets in the eye would affect the optical clarity of silicone oil and might cause visual symptoms.
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Chao Y, Shum HC. Emerging aqueous two-phase systems: from fundamentals of interfaces to biomedical applications. Chem Soc Rev 2020; 49:114-142. [DOI: 10.1039/c9cs00466a] [Citation(s) in RCA: 138] [Impact Index Per Article: 34.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
This review summarizes recent advances of aqueous two-phase systems (ATPSs), particularly their interfaces, with a focus on biomedical applications.
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Zhang Y, Fu X, Guo W, Deng Y, Binks BP, Shum HC. Electrocoalescence of liquid marbles driven by embedded electrodes for triggering bioreactions. LAB ON A CHIP 2019; 19:3526-3534. [PMID: 31544191 DOI: 10.1039/c9lc00722a] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Liquid marbles need to be controlled precisely to benefit applications, for instance, as microreactors on digital microfluidic platforms for chemical and biological assays. In this work, a strategy is introduced to coalesce liquid marbles via electrostatics, where two liquid marbles in contact can coalesce when a sufficiently high voltage is applied to embedded electrodes. With the understanding of the mechanism of coalescence through relating the electric stress and the restoring capillary pressure at the contact interface, this method coalesces liquid marbles efficiently. When compared with the existing electrocoalescence method, our approach does not require immersion of electrodes to trigger coalescence. We demonstrate this to exchange the medium for the culture of cell spheroids and to measure the cell metabolic activity through a CCK-8 assay. The manipulation of liquid marbles driven by electrostatics creates new opportunities to conduct chemical reactions and biomedical assays in these novel microreactors.
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Lo HY, Liu Y, Mak SY, Xu Z, Chao Y, Li KJ, Shum HC, Xu L. Diffusion-Dominated Pinch-Off of Ultralow Surface Tension Fluids. PHYSICAL REVIEW LETTERS 2019; 123:134501. [PMID: 31697525 DOI: 10.1103/physrevlett.123.134501] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2019] [Revised: 07/15/2019] [Indexed: 06/10/2023]
Abstract
We study the breakup of a liquid thread inside another liquid at different surface tensions. In general, the pinch-off of a liquid thread is governed by the dynamics of fluid flow. However, when the interfacial tension is ultralow (2-3 orders lower than normal liquids), we find that the pinch-off dynamics can be governed by bulk diffusion. By studying the velocity and the profile of the pinch-off, we explain why the diffusion-dominated pinch-off takes over the conventional breakup at ultralow surface tensions.
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Chan YK, Yan WH, Hung LT, Chao Y, Wu J, Shum HC. All-Aqueous Thin-Film-Flow-Induced Cell-Based Monolayers. ACS APPLIED MATERIALS & INTERFACES 2019; 11:22869-22877. [PMID: 31145590 DOI: 10.1021/acsami.9b06382] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Cells in vitro usually require a solid scaffold to attach and form two-dimensional monolayer structures. To obtain a substrate-free cell monolayer, long culture time and specific detaching procedures are required. In this study, a thin-film-flow-induced strategy is reported to overcome the challenges of assembling in vitro scaffold-free monolayered cell aggregates. The assembly is driven by a dewetting-like thin-film withdrawal along all-aqueous interfaces characterized by a low interfacial tension. The withdrawal process drives the cells adsorbed on the liquid film to aggregate and assemble into an organized and compact monolayer. This strategy is not limited to biological cells but also colloidal particles, as demonstrated by the assembly of hybrid cell-particle monolayers. The versatility offered by this approach suggests new opportunities in understanding early tissue formation and functionalizing cell monolayer aggregates by colloidal particles with customized functions.
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Li J, Kong T, Yu J, Lee KH, Tang YH, Kwok KW, Kim JT, Shum HC. Electrocoiling-guided printing of multiscale architectures at single-wavelength resolution. LAB ON A CHIP 2019; 19:1953-1960. [PMID: 31044199 DOI: 10.1039/c9lc00145j] [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
The rope coiling observed in liquid ink with high viscosity has been exploited in additive printing to fabricate architectures with periodically curled structures and tune their mechanical properties. However, the control over the coiling path relying on mechanical motion restricts the spatiotemporal resolution. We develop an electrically assisted high-resolution technique to manipulate coiling paths of viscous ink and structures of the deposited filament. By spatially programming the voltage applied onto the viscous ink, we show that the switching between different filament structures can be accomplished at single wavelength resolution, facilitating the rapid and accurate construction of sophisticated patterns. Furthermore, translational guiding of the electrocoiling enables rapid printing of filaments with complex structures at a line speed of 102 mm s-1. With a simplified trajectory of the printing head, large-area and multiscale patterns can be printed at an unprecedented speed; for instance, centimeter-sized architectures constructed from nanofibers with micron-sized curled structures can be completed in a few minutes. By enabling the printing of complex fiber networks with tunable shape and density, our work provides a route towards custom-design of fiber architectures with unique features such as spatially varying mechanical properties.
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Nan L, Yang Z, Lyu H, Lau KYY, Shum HC. A Microfluidic System for One-Chip Harvesting of Single-Cell-Laden Hydrogels in Culture Medium. ACTA ACUST UNITED AC 2019; 3:e1900076. [PMID: 32648695 DOI: 10.1002/adbi.201900076] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 04/27/2019] [Indexed: 12/28/2022]
Abstract
Single-cell analysis has shown great potential to fully quantify the distribution of cellular behaviors among a population of individuals. Through isolation and preservation of single cells in the aqueous phase, droplet encapsulation followed by gelation enables high-throughput analysis in biocompatible microgels. However, the lack of control over the number of cells encapsulated and complicated gelation processes significantly limit its efficiency. Here, a microfluidic system for one-chip harvesting of single-cell-laden microgels is presented. Through ultraviolet irradiation, an on-chip gelation technique is seamlessly combined with droplet generation to realize high-throughput fabrication of microscale hydrogels in microfluidic channel. Moreover, a sorting module is introduced to simultaneously complete cell-laden microgel selection and transfer into culture medium. To demonstrate the efficiency of this method, two types of single cells are respectively encapsulated and collected, showing desirable single-cell encapsulation and cell viability. This technique realizes integrated droplet gelation, microgel sorting, and transfer into culture medium, allowing high-throughput analysis of single cells and comprehensive understanding of the cellular specificity.
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Li SS, Ip CKM, Tang MYH, Tang MKS, Tong Y, Zhang J, Hassan AA, Mak ASC, Yung S, Chan TM, Ip PP, Lee CL, Chiu PCN, Lee LTO, Lai HC, Zeng JZ, Shum HC, Wong AST. Sialyl Lewis x-P-selectin cascade mediates tumor-mesothelial adhesion in ascitic fluid shear flow. Nat Commun 2019; 10:2406. [PMID: 31160622 PMCID: PMC6547673 DOI: 10.1038/s41467-019-10334-6] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Accepted: 04/29/2019] [Indexed: 01/01/2023] Open
Abstract
Organ-specific colonization suggests that specific cell–cell recognition is essential. Yet, very little is known about this particular interaction. Moreover, tumor cell lodgement requires binding under shear stress, but not static, conditions. Here, we successfully isolate the metastatic populations of cancer stem/tumor-initiating cells (M-CSCs). We show that the M-CSCs tether more and roll slower than the non-metastatic (NM)-CSCs, thus resulting in the preferential binding to the peritoneal mesothelium under ascitic fluid shear stress. Mechanistically, this interaction is mediated by P-selectin expressed by the peritoneal mesothelium. Insulin-like growth factor receptor-1 carrying an uncommon non-sulfated sialyl-Lewisx (sLex) epitope serves as a distinct P-selectin binding determinant. Several glycosyltransferases, particularly α1,3-fucosyltransferase with rate-limiting activity for sLex synthesis, are highly expressed in M-CSCs. Tumor xenografts and clinical samples corroborate the relevance of these findings. These data advance our understanding on the molecular regulation of peritoneal metastasis and support the therapeutic potential of targeting the sLex-P-selectin cascade. Tumor cell in the peritoneum are often exposed to shear forces generated by ascitic flow during metastasis. Here, the authors show that metastatic cancer stem cells tether more and roll slower than the non-metastatic counterparts, and that sialyl-Lewisx -P-selectin axis mediates peritoneal metastasis.
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Lu Y, Chan YK, Lau LH, Chao Y, Shih KC, Lai SM, Wong D, Shum HC. Adhesion of silicone oil and emulsification: an in vitro assessment using a microfluidic device and 'Eye-on-a-Chip'. Acta Ophthalmol 2019; 97:313-318. [PMID: 30484963 DOI: 10.1111/aos.13982] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 11/04/2018] [Indexed: 11/28/2022]
Abstract
PURPOSE Silicone oil (SiO) with additives of high-molecular-weight (HMW) SiO molecules, eases both the injection and removal. When used inside an eye, it remains unclear how increasing extensional viscosity of SiO might reduce emulsification. Using cell-lined models, this study aims to understand the reason why SiO with HMW is less prone to emulsification. METHODS The adhesion of SiO was studied and recorded in a cell-coated microchannel by optical microscopy. The resistance of SiO against emulsification was tested on another cell-coated eye-on-a-chip platform, which was subject to simulated saccadic eye movements, for 4 days. Silicone oil (SiO) candidates with HMW, SiOHMW 2000 and SiOHMW 5000 , and their counterparts SiO2000 and SiO5000 without HMW, were tested. The quantity of the SiO emulsified droplets formed was assessed daily by optical microscopy. RESULTS When flowing in the microchannel, SiO adheres on the cell-coated substrate. The number of droplets is generally lower in SiO with HMW than their counterparts. At the end of the experiment, the average numbers of droplets in SiO2000 (29.1 ± 41.0) and SiO5000 (9.1 ± 19.5) are higher than those in SiOHMW 2000 (6.0 ± 4.5) and SiOHMW 5000 (5.6 ± 4.1). CONCLUSION A new mechanism of emulsification of SiO is proposed: SiO adheres to ocular tissue to form emulsified droplets. The presence of HMW, which increases the extensional viscosity, may resist the break-up of SiO from the substrate to form emulsified droplets. When tested in a physiologically representative platform, the use of HMW in SiO generally reduces the number of droplets formed in vitro.
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Fraser LA, Cheung YW, Kinghorn AB, Guo W, Shiu SCC, Jinata C, Liu M, Bhuyan S, Nan L, Shum HC, Tanner JA. Microfluidic Technology for Nucleic Acid Aptamer Evolution and Application. ACTA ACUST UNITED AC 2019; 3:e1900012. [PMID: 32627415 DOI: 10.1002/adbi.201900012] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 03/12/2019] [Indexed: 12/18/2022]
Abstract
The intersection of microfluidics and aptamer technologies holds particular promise for rapid progress in a plethora of applications across biomedical science and other areas. Here, the influence of microfluidics on the field of aptamers, from traditional capillary electrophoresis approaches through innovative modern-day approaches using micromagnetic beads and emulsion droplets, is reviewed. Miniaturizing aptamer-based bioassays through microfluidics has the potential to transform diagnostics and embedded biosensing in the coming years.
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Mak CM, Mok NS, Shum HC, Siu WK, Chong YK, Lee HHC, Fong NC, Tong SF, Lee KW, Ching CK, Chen SPL, Cheung WL, Tso CB, Poon WM, Lau CL, Lo YK, Tsui PT, Shum SF, Lee KC. Sudden arrhythmia death syndrome in young victims: a five-year retrospective review and two-year prospective molecular autopsy study by next-generation sequencing and clinical evaluation of their first-degree relatives. Hong Kong Med J 2019; 25:21-9. [PMID: 30670673 DOI: 10.12809/hkmj187256] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVE Sudden arrhythmia death syndrome (SADS) accounts for about 30% of causes of sudden cardiac death (SCD) in young people. In Hong Kong, there are scarce data on SADS and a lack of experience in molecular autopsy. We aimed to investigate the value of molecular autopsy techniques for detecting SADS in an East Asian population. METHODS This was a two-part study. First, we conducted a retrospective 5-year review of autopsies performed in public mortuaries on young SCD victims. Second, we conducted a prospective 2-year study combining conventional autopsy investigations, molecular autopsy, and cardiac evaluation of the first-degree relatives of SCD victims. A panel of 35 genes implicated in SADS was analysed by next-generation sequencing. RESULTS There were 289 SCD victims included in the 5-year review. Coronary artery disease was the major cause of death (35%); 40% were structural heart diseases and 25% were unexplained. These unexplained cases could include SADS-related conditions. In the 2-year prospective study, 21 SCD victims were examined: 10% had arrhythmogenic right ventricular cardiomyopathy, 5% had hypertrophic cardiomyopathy, and 85% had negative autopsy. Genetic analysis showed 29% with positive heterozygous genetic variants; six variants were novel. One third of victims had history of syncope, and 14% had family history of SCD. More than half of the 11 first-degree relatives who underwent genetic testing carried related genetic variants, and 10% had SADS-related clinical features. CONCLUSION This pilot feasibility study shows the value of incorporating cardiac evaluation of surviving relatives and next-generation sequencing molecular autopsy into conventional forensic investigations in diagnosing young SCD victims in East Asian populations. The interpretation of genetic variants in the context of SCD is complicated and we recommend its analysis and reporting by qualified pathologists.
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Deng Y, Ma Q, Yuan H, Lum GC, Shum HC. Development of dual-component protein microparticles in all-aqueous systems for biomedical applications. J Mater Chem B 2019. [DOI: 10.1039/c8tb03074j] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Protein microparticles assisted by an emulsion droplet template have shown great promise in drug/cell delivery and tissue engineering, as well as diagnosis and treatment of diseases.
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Yuan H, Chao Y, Li S, Tang MYH, Huang Y, Che Y, Wong AST, Zhang T, Shum HC. Picoinjection-Enabled Multitarget Loop-Mediated Isothermal Amplification for Detection of Foodborne Pathogens. Anal Chem 2018; 90:13173-13177. [PMID: 30354065 DOI: 10.1021/acs.analchem.8b03673] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
In this study, we develop a method to detect multiple DNAs of foodborne pathogens by encapsulating emulsion droplets for loop-mediated isothermal amplification (LAMP). In contrast to the traditional bulk-phase LAMP, which involves a labor-intensive mixing process, with our method, different primers are automatically mixed with DNA samples and LAMP buffers after picoinjection. By directly observing and analyzing the fluorescence intensity of the resultant droplets, one can detect DNA from different pathogens, with a detection limit 500 times lower than that obtained by bulk-phase LAMP. We further demonstrate the ability to quantify bacteria concentration by detecting bacterial DNA in practical samples, showing great potential in monitoring water resources and their contamination by pathogenic bacteria.
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Fu X, Zhang Y, Yuan H, Binks BP, Shum HC. Controlled Actuation of Liquid Marbles on a Dielectric. ACS APPLIED MATERIALS & INTERFACES 2018; 10:34822-34827. [PMID: 30265518 DOI: 10.1021/acsami.8b13111] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Motivated by the great potential of droplet microreactors for chemical and biological applications, a general and robust method utilizing an electric field is developed for sustained, directional and two-dimensional manipulation of nonwetting droplets (termed "liquid marbles"). With the understanding of the mechanism of actuation, this method allows individual liquid marbles to be actuated and coalesced on demand by fine-tuning the driving voltage. Moreover, in our system, cross-contamination between marbles during manipulation is avoided as confirmed by the absence of any trace DNA after amplification using a loop-mediated isothermal amplification reaction.
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Chao Y, Mak SY, Rahman S, Zhu S, Shum HC. Generation of High-Order All-Aqueous Emulsion Drops by Osmosis-Driven Phase Separation. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2018; 14:e1802107. [PMID: 30118584 DOI: 10.1002/smll.201802107] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2018] [Revised: 07/28/2018] [Indexed: 05/14/2023]
Abstract
Droplets containing ternary mixtures can spontaneously phase-separate into high-order structures upon a change in composition, which provides an alternative strategy to form multiphase droplets. However, existing strategies always involve nonaqueous solvents that limit the potential applications of the resulting multiple droplets, such as encapsulation of biomolecules. Here, a robust approach to achieve high-order emulsion drops with an all-aqueous nature from two aqueous phases by osmosis-induced phase separation on a microfluidic platform is presented. This technique is enabled by the existence of an interface of the two aqueous phases and phase separation caused by an osmolality difference between the two phases. The complexity of emulsion drops induced by phase separation could be controlled by varying the initial concentration of solutes and is systematically illustrated in a state diagram. In particular, this technique is utilized to successfully achieve high-order all-aqueous droplets in a different aqueous two-phase system. The proposed method is simple since it only requires two initial aqueous solutions for generating multilayered, organic-solvent-free all-aqueous emulsion drops, and thus these multiphase emulsion drops can be further tailored to serve as highly biocompatible material templates.
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Song Y, Michaels TCT, Ma Q, Liu Z, Yuan H, Takayama S, Knowles TPJ, Shum HC. Budding-like division of all-aqueous emulsion droplets modulated by networks of protein nanofibrils. Nat Commun 2018; 9:2110. [PMID: 29844310 PMCID: PMC5974351 DOI: 10.1038/s41467-018-04510-3] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2017] [Accepted: 04/30/2018] [Indexed: 01/01/2023] Open
Abstract
Networks of natural protein nanofibrils, such as cytoskeletal filaments, control the shape and the division of cells, yet mimicking this functionality in a synthetic setting has proved challenging. Here, we demonstrate that artificial networks of protein nanofibrils can induce controlled deformation and division of all-aqueous emulsion droplets with budding-like morphologies. We show that this process is driven by the difference in the immersional wetting energy of the nanofibril network, and that both the size and the number of the daughter droplets formed during division can be controlled by modulating the fibril concentration and the chemical properties of the fibril network. Our results demonstrate a route for achieving biomimetic division with synthetic self-assembling fibrils and offer an engineered approach to regulate the morphology of protein gels.
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Chao Y, Mak SY, Ma Q, Wu J, Ding Z, Xu L, Shum HC. Emergence of Droplets at the Nonequilibrium All-Aqueous Interface in a Vertical Hele-Shaw Cell. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:3030-3036. [PMID: 29465242 DOI: 10.1021/acs.langmuir.7b04168] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The interfacial phenomena at liquid-liquid interfaces remain the subject of constant fascination in science and technology. Here, we show that fingers forming at the interface of nonequilibrium all-aqueous systems can spontaneously break into an array of droplets. The dynamic formation of droplets at the water-water (w/w) interface is observed when a less dense aqueous phase, for instance, the dextran solution, is placed on a denser aqueous phase, the polyethylene glycol solution, in a vertical Hele-Shaw cell. Because of the gradual diffusion of water from the upper phase into the lower phase, a dense layer appears at the nonequilibrium w/w interface. As a result, a periodic array of fingers emerge and sink. Remarkably, these fingers break up and an array of droplets are emitted from the interface. We characterize the wavelength of fingering by measuring the average distance between the dominant fingers. By varying the initial concentrations of the two nonequilibrium aqueous phases, we identify experimentally a phase diagram with a wide parameter space in which finger breaking occurs. Finally, plenty of droplets, spontaneously formed when one phase is continuously deposited onto another aqueous phase, further confirm the robustness of our experimental results. Our work suggests a simple yet efficient approach with a potential upscalability to generate all-aqueous droplets.
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Ma Q, Yuan H, Song Y, Chao Y, Mak SY, Shum HC. Partitioning-dependent conversion of polyelectrolyte assemblies in an aqueous two-phase system. SOFT MATTER 2018; 14:1552-1558. [PMID: 29443349 DOI: 10.1039/c7sm02275a] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
Partitioning refers to the distribution of solute molecules in the two immiscible phases of a mixture of two solutions, such as an aqueous two-phase system (ATPS). The partitioning of RNA and peptide has been adjusted in situ to facilitate their assembly into intracellular membraneless organelles. Despite the immense potential of this approach in artificial systems, a partitioning-dependent assembly of macromolecules has been limited, due to the sophisticated processing associated with their in situ modification. Here we demonstrate an approach to direct the assembly of polyelectrolytes in an ATPS through varying their partitioning via pH changes. Microcapsules can be converted to microgel particles as the polyelectrolytes selectively partition to different emulsion phases when changing pH. Such partitioning-dependence can also be equally applied for complexing hydrophilic nanoparticles with polyelectrolytes in an ATPS. By enabling access of hydrophilic materials across the aqueous interface freely, the ATPS allows modification of their intrinsic properties in situ; this advantage will inspire more versatile control over the partitioning of hydrophilic materials and will create new multi-functional biomaterials.
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Jeyhani M, Mak SY, Sammut S, Shum HC, Hwang DK, Tsai SSH. Controlled Electrospray Generation of Nonspherical Alginate Microparticles. Chemphyschem 2018; 19:2113-2118. [PMID: 29228474 DOI: 10.1002/cphc.201701094] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Indexed: 11/10/2022]
Abstract
Electrospraying is a technique used to generate microparticles in a high throughput manner. For biomedical applications, a biocompatible electrosprayed material is often desirable. Using polymers, such as alginate hydrogels, makes it possible to create biocompatible and biodegradable microparticles that can be used for cell encapsulation, to be employed as drug carriers, and for use in 3D cell culturing. Evidence in the literature suggests that the morphology of the biocompatible microparticles is relevant in controlling the dynamics of the microparticles in drug delivery and 3D cell culturing applications. Yet, most electrospray-based techniques only form spherical microparticles, and there is currently no widely adopted technique for producing nonspherical microparticles at a high throughput. Here, we demonstrate the generation of nonspherical biocompatible alginate microparticles by electrospraying, and control the shape of the microparticles by varying experimental parameters such as chemical concentration and the distance between the electrospray tip and the particle-solidification bath. Importantly, we show that these changes to the experimental setup enable the synthesis of different shaped particles, and the systematic change in parameters, such as chemical concentration, result in monotonic changes to the particle aspect ratio. We expect that these results will find utility in many biomedical applications that require biocompatible microparticles of specific shapes.
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Chan YK, Cheng HC, Wu J, Tang YHM, Chan ST, Wong D, Shum HC. A perfluorobutylpentane (F4H5)-based solution for the removal of residual emulsified silicone oil. Acta Ophthalmol 2018; 96:e38-e45. [PMID: 28616869 DOI: 10.1111/aos.13465] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 03/25/2017] [Indexed: 11/29/2022]
Abstract
PURPOSE The emulsification of silicone oil (SO) is associated with many complications. In this study, we investigate a new SO solvent, perfluorobutylpentane (F4H5) with 1% by volume of perfluorinated polyethers-polyethylene glycol-perfluorinated polyethers (PFPE-PEG-PFPE) triblock copolymer, for removing emulsified droplets. METHODS An in vitro 3D printed model eye chamber was used to evaluate the efficiency of the three test liquids in removing SO droplets, namely saline, F4H5 and F4H5 with surfactant PFPE-PEG-PFPE. The numbers of SO droplets were quantified using a Coulter Counter. The stability of double emulsion formed was tested with a fluidic device based on electro-coalescence. Two retinal cell lines were used to test the biocompatibility of the liquids. RESULTS The mean number of droplets remaining in the eye chamber after rinsing with a solution of F4H5 with surfactant was 13 315 ± 4620/ml compared to saline (23 460 ± 7595/ml; p < 0.05). The double emulsion was found to be highly stable. The biocompatibility of F4H5 and the surfactant was similar to that of the saline control. CONCLUSION By adding a small amount of surfactant, the resultant F4H5 solution is able to promote double emulsification and remove more SO droplets. Although further in vivo safety studies are necessary before clinical trials, the result of our study suggests that F4H5 with surfactant is a promising Rinsing Solution for removing emulsified droplets. This work therefore translates a well-known phenomenon in emulsion science to tackle the emulsification problem observed in the routine vitreoretinal surgery.
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Mak SY, Chao Y, Rahman S, Shum HC. Droplet Formation by Rupture of Vibration-Induced Interfacial Fingers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:926-932. [PMID: 29094601 DOI: 10.1021/acs.langmuir.7b02633] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
By imposing vibration to a core-annular flow of an aqueous two-phase system (ATPS) with ultralow interfacial tension, we observe a liquid finger protruding from the interface of an expanding jet. We find that the protruded finger breaks up only when its length-to-width ratio exceeds a threshold value. The breakup follows a constant wavelength-to-width ratio that is consistent with that of breakup under Rayleigh-Plateau instability. The mechanism is applicable to aqueous two-phase systems with a large range of viscosity ratios. The protruded finger can break up into small droplets that are monodisperse in size, controllable in generation frequency under a wide range of flow rates. This work suggests a way to generate small water-water droplets with high monodispersity and production rate from a single nozzle.
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Chan YK, Czanner G, Shum HC, Williams RL, Cheung N, Wong D. Towards better characterization and quantification of emulsification of silicone oil in vitro. Acta Ophthalmol 2017; 95:e385-e392. [PMID: 27775235 DOI: 10.1111/aos.13258] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 07/25/2016] [Indexed: 12/01/2022]
Abstract
PURPOSE Emulsification is related to complications arising from silicone oil (SO) tamponade. Currently, there is no widely accepted method for testing the propensity of SO to emulsify that are physiologically realistic and quantitative. METHODS We compared different ways of inducing emulsification namely vortex mixing, sonication and homogenization. Silicone oil (SO) emulsification was quantitatively assessed using the Coulter counter and laser light scattering. The in vitro results are compared with the droplet size distribution profile of vitreous clinical washout. Conventional SO was compared with two novel SO blends with high-molecular-weight (HMW) additives (SOHMW2000 and SOHMW5000 ). RESULTS Of the three methods for inducing emulsification, homogenization generated the most consistent emulsion samples with the smallest variance. The results from the Coulter counter measurement correlated strongly with the laser light scattering measurement within the range of 1 to 30 µm. The droplet size distribution profiles from human eyes were similar to that of emulsions generated in vitro by homogenization. The human size distribution profile was within the range of values obtained by the in vitro experiment. Compared to the conventional SO, the emulsion droplet counts for the new SO blends were significantly lower (SOHMW2000 and SOHMW5000 were 79% (±17%) and 49% (±18%) of the SO2000 and SO5000 , respectively; p = 0.03 and p = 0.002). CONCLUSION Emulsion generated in vitro by homogenization has similar droplet size profile as human eyes filled with SO. Using this method to induce emulsion, SO blends with HMW additives demonstrated less propensity to emulsification with lower droplet counts compared to conventional SO with similar shear viscosity.
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Li SS, Ip CKM, Hassan AA, Tang MYH, Yung S, Chan TM, Shum HC, Wong AST. Abstract 5885: Sialyl Lewis X-P-selectin connection between ovarian tumor-mesothelium in early stage metastasis. Cancer Res 2017. [DOI: 10.1158/1538-7445.am2017-5885] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Metastasis is one of the major challenges for the treatment of ovarian cancer. Unlike other solid tumors, ovarian cancer primarily disseminates within the peritoneal cavity. A crucial step in metastasis formation is the adhesion of ovarian cancer cells onto the peritoneal mesothelium under ascitic shear flow. However, the adhesion mechanisms engaged in this tumor-mesothelium interaction remain elusive due to a lack of physiologically relevant model to manipulate and investigate this dynamic process. In this study, using a 3D microfluidic platform, we found that the metastatic population of cancer stem cells (M-CSCs) exhibited slower rolling velocity and higher binding ability to the peritoneal mesothelium than non-metastatic (NM)-CSCs under flow condition. This adhesion cascade was mediated by P-selectin which expressed on the peritoneal mesothelium. The key carbohydrate determinant on M-CSCs was a glycoprotein, but not a glycolipid, with its recognition as sialyl-Lewis X (sLeX) in a sialic acid- and fucose-dependent manner. Moreover, several glycosyltransferase genes including B4GALT4, ST3GAL3, ST3GAL4 and FUT-5 involved the synthesis of sLeX were upregulated in M-CSCs. Knocking down FUT-5 significantly inhibited ovarian tumor cell adhesion on the mesothelium in vitro and reduced the metastatic potential in vivo. Taken together, our findings revealed that a distinct sLeX-P-selectin axis of ovarian tumor-mesothelium interaction in early metastasis and may offer the possibility of new therapeutic targets. (This work is supported by RGC grant 17122014)
Citation Format: Shan-Shan Li, Carman K. M. Ip, Ayon A. Hassan, Matthew Y. H. Tang, Susan Yung, Tak-Mao Chan, Ho Cheung Shum, Alice S. T. Wong. Sialyl Lewis X-P-selectin connection between ovarian tumor-mesothelium in early stage metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 5885. doi:10.1158/1538-7445.AM2017-5885
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