39 results found
Chen M, Bolognesi G, Vladisavljevic GT, 2021, Crosslinking Strategies for the Microfluidic Production of Microgels, MOLECULES, Vol: 26
Zhang S, Contini C, Hindley J, et al., 2021, Engineering motile aqueous phase-separated droplets via liposome stabilisation, Nature Communications, Vol: 12, Pages: 1-11, ISSN: 2041-1723
There are increasing efforts to engineer functional compartments that mimic cellular behaviours from the bottom-up. One behaviour that is receiving particular attention is motility, due to its biotechnological potential and ubiquity in living systems. Many existing platforms make use of the Marangoni effect to achieve motion in water/oil (w/o) droplet systems. However, most of these systems are unsuitable for biological applications due to biocompatibility issues caused by the presence of oil phases. Here we report a biocompatible all aqueous (w/w) PEG/dextran Pickering-like emulsion system consisting of liposome-stabilised cell-sized droplets, where the stability can be easily tuned by adjusting liposome composition and concentration. We demonstrate that the compartments are capable of negative chemotaxis: these droplets can respond to a PEG/dextran polymer gradient through directional motion down to the gradient. The biocompatibility, motility and partitioning abilities of this droplet system offers new directions to pursue research in motion-related biological processes.
Singh N, Vladisavljevic GT, Nadal F, et al., 2020, Reversible Trapping of Colloids in Microgrooved Channels via Diffusiophoresis under Steady-State Solute Gradients, PHYSICAL REVIEW LETTERS, Vol: 125, ISSN: 0031-9007
Al Nuumani R, Smoukov SK, Bolognesi G, et al., 2020, Highly Porous Magnetic Janus Microparticles with Asymmetric Surface Topology, LANGMUIR, Vol: 36, Pages: 12702-12711, ISSN: 0743-7463
Vivek A, Bolognesi G, Elani Y, 2020, Fusing artificial cell compartments and lipid domains using optical traps: a tool to modulate membrane composition and phase behaviour, Micromachines, Vol: 11, ISSN: 2072-666X
New technologies for manipulating biomembranes have vast potential to aid the understanding of biological phenomena, and as tools to sculpt novel artificial cell architectures for synthetic biology. The manipulation and fusion of vesicles using optical traps is amongst the most promising due to the level of spatiotemporal control it affords. Herein, we conduct a suite of feasibility studies to show the potential of optical trapping technologies to (i) modulate the lipid composition of a vesicle by delivering new membrane material through fusion events and (ii) manipulate and controllably fuse coexisting membrane domains for the first time. We also outline some noteworthy morphologies and transitions that the vesicle undergoes during fusion, which gives us insight into the mechanisms at play. These results will guide future exploitation of laser-assisted membrane manipulation methods and feed into a technology roadmap for this emerging technology.
Ogunyinka O, Wright A, Bolognesi G, et al., 2020, An integrated microfluidic chip for generation and transfer of reactive species using gas plasma, MICROFLUIDICS AND NANOFLUIDICS, Vol: 24, ISSN: 1613-4982
Friddin M, Bolognesi G, Salehi-Reyhani A, et al., 2019, Direct manipulation of liquid ordered lipid membrane domains using optical traps, Communications Chemistry, Vol: 2, Pages: 1-7, ISSN: 2399-3669
Multicomponent lipid bilayers can give rise to coexisting liquid domains that are thought to influence a host of cellular activities. There currently exists no method to directly manipulate such domains, hampering our understanding of their significance. Here we report a system that allows individual liquid ordered domains that exist in a liquid disordered matrix to be directly manipulated using optical tweezers. This allows us to drag domains across the membrane surface of giant vesicles that are adhered to a glass surface, enabling domain location to be defined with spatiotemporal control. We can also use the laser to select individual vesicles in a population to undergo mixing/demixing by locally heating the membrane through the miscibility transition, demonstrating a further layer of control. This technology has potential as a tool to shed light on domain biophysics, on their role in biology, and in sculpting membrane assemblies with user-defined membrane patterning.
Balzamo G, Singh N, Wang N, et al., 2019, 3D Arrays of Super-Hydrophobic Microtubes from Polypore Mushrooms as Naturally-Derived Systems for Oil Absorption, MATERIALS, Vol: 12
Trantidou T, Friddin M, Gan KB, et al., 2018, Mask-free laser lithography for rapid and low-cost microfluidic device fabrication, Analytical Chemistry, Vol: 90, Pages: 13915-13921, ISSN: 0003-2700
Microfluidics has become recognized as a powerful platform technology associated with a constantly increasing array of applications across the life sciences. This surge of interest over recent years has led to an increased demand for microfluidic chips, resulting in more time being spent in the cleanroom fabricating devices using soft lithography—a slow and expensive process that requires extensive materials, training and significant engineering resources. This bottleneck limits platform complexity as a byproduct of lengthy delays between device iterations and affects the time spent developing the final application. To address this problem, we report a new, rapid, and economical approach to microfluidic device fabrication using dry resist films to laminate laser cut sheets of acrylic. We term our method laser lithography and show that our technique can be used to engineer 200 μm width channels for assembling droplet generators capable of generating monodisperse water droplets in oil and micromixers designed to sustain chemical reactions. Our devices offer high transparency, negligible device to device variation, and low X-ray background scattering, demonstrating their suitability for real-time X-ray-based characterization applications. Our approach also requires minimal materials and apparatus, is cleanroom free, and at a cost of around $1.00 per chip could significantly democratize device fabrication, thereby increasing the interdisciplinary accessibility of microfluidics.
Al Nuumani R, Bolognesi G, Vladisavljevic GT, 2018, Microfluidic Production of Poly(1,6-hexanediol diacrylate)-Based Polymer Microspheres and Bifunctional Microcapsules with Embedded TiO2 Nanoparticles, LANGMUIR, Vol: 34, Pages: 11822-11831, ISSN: 0743-7463
Bolognesi G, Friddin MS, Salehi-Reyhani S, et al., 2018, Sculpting and fusing biomimetic vesicle networks using optical tweezers, Nature Communications, Vol: 9, Pages: 1-11, ISSN: 2041-1723
Constructing higher-order vesicle assemblies has discipline-spanning potential from responsive soft-matter materials to artificial cell networks in synthetic biology. This potential is ultimately derived from the ability to compartmentalise and order chemical species in space. To unlock such applications, spatial organisation of vesicles in relation to one another must be controlled, and techniques to deliver cargo to compartments developed. Herein, we use optical tweezers to assemble, reconfigure and dismantle networks of cell-sized vesicles that, in different experimental scenarios, we engineer to exhibit several interesting properties. Vesicles are connected through double-bilayer junctions formed via electrostatically controlled adhesion. Chemically distinct vesicles are linked across length scales, from several nanometres to hundreds of micrometres, by axon-like tethers. In the former regime, patterning membranes with proteins and nanoparticles facilitates material exchange between compartments and enables laser-triggered vesicle merging. This allows us to mix and dilute content, and to initiate protein expression by delivering biomolecular reaction components.
Karamdad K, Hindley J, Friddin MS, et al., 2018, Engineering thermoresponsive phase separated vesicles formed via emulsion phase transfer as a content-release platform, Chemical Science, Vol: 9, Pages: 4851-4858, ISSN: 2041-6520
Giant unilamellar vesicles (GUVs) are a well-established tool for the study of membrane biophysics and are increasingly used as artificial cell models and functional units in biotechnology. This trend is driven by the development of emulsion-based generation methods such as Emulsion Phase Transfer (EPT), which facilitates the encapsulation of almost any water-soluble compounds (including biomolecules) regardless of size or charge, is compatible with droplet microfluidics, and allows GUVs with asymmetric bilayers to be assembled. However, the ability to control the composition of membranes formed via EPT remains an open question; this is key as composition gives rise to an array of biophysical phenomena which can be used to add functionality to membranes. Here, we evaluate the use of GUVs constructed via this method as a platform for phase behaviour studies and take advantage of composition-dependent features to engineer thermally-responsive GUVs. For the first time, we generate ternary GUVs (DOPC/DPPC/cholesterol) using EPT, and by compensating for the lower cholesterol incorporation efficiencies, show that these possess the full range of phase behaviour displayed by electroformed GUVs. As a demonstration of the fine control afforded by this approach, we demonstrate release of dye and peptide cargo when ternary GUVs are heated through the immiscibility transition temperature, and show that release temperature can be tuned by changing vesicle composition. We show that GUVs can be individually addressed and release triggered using a laser beam. Our findings validate EPT as a suitable method for generating phase separated vesicles and provide a valuable proof-of-concept for engineering content release functionality into individually addressable vesicles, which could have a host of applications in the development of smart synthetic biosystems.
Barlow NE, Bolognesi G, Haylock S, et al., 2017, Rheological Droplet Interface Bilayers (rheo-DIBs): Probing the Unstirred Water Layer Effect on Membrane Permeability via Spinning Disk Induced Shear Stress, Scientific Reports, Vol: 7, ISSN: 2045-2322
A new rheological droplet interface bilayer (rheo-DIB) device is presented as a tool to apply shear stress on biological lipid membranes. Despite their exciting potential for affecting high-throughput membrane translocation studies, permeability assays conducted using DIBs have neglected the effect of the unstirred water layer (UWL). However as demonstrated in this study, neglecting this phenomenon can cause significant underestimates in membrane permeability measurements which in turn limits their ability to predict key processes such as drug translocation rates across lipid membranes. With the use of the rheo-DIB chip, the effective bilayer permeability can be modulated by applying shear stress to the droplet interfaces, inducing flow parallel to the DIB membranes. By analysing the relation between the effective membrane permeability and the applied stress, both the intrinsic membrane permeability and UWL thickness can be determined for the first time using this model membrane approach, thereby unlocking the potential of DIBs for undertaking diffusion assays. The results are also validated with numerical simulations.
We present a simple method for the multiplexed formation ofdroplet interface bilayers (DIBs) using a mechanically operatedlinear acrylic chamber array. To demonstrate the functionality ofthe chip design, a lipid membrane permeability assay is performed.We show that multiple, symmetric DIBs can be created andseparated using this robust low-cost approach.
Chan CL, Bolognesi G, Bhandarkar A, et al., 2016, DROPLAY: laser writing of functional patterns within biological microdroplet displays, Lab on a Chip, Vol: 16, Pages: 4621-4627, ISSN: 1473-0197
In this study, we introduce an optofluidic method for the rapid construction of large-area cell-sized droplet assemblieswith user-defined re-writable two-dimensional patterns of functional droplets. Light responsive water-in-oil dropletscapable of releasing fluorescent dye molecules upon exposure were generated and self-assembled into arrays in amicrofluidic device. This biological architecture was exploited by the scanning laser of a confocal microscope to ‘write’ userdefined patterns of differentiated (fluorescent) droplets in a network of originally undifferentiated (non-fluorescent)droplets. As a result, long lasting images were produced on a droplet fabric with droplets acting as pixels of a biologicalmonitor, which can be erased and re-written on-demand. Regio-specific light-induced droplet differentiation within a largepopulation of droplets provides a new paradigm for the rapid construction of bio-synthetic systems with potential as tissuemimics and biological display materials.
Friddin MS, Bolognesi G, Elani Y, et al., 2016, Optically assembled droplet interface bilayer (OptiDIB) networks from cell-sized microdroplets, Soft Matter, Vol: 12, Pages: 7731-7734, ISSN: 1744-6848
We report a new platform technology to systematically assemble droplet interface bilayer (DIB) networks in user-defined 3D architectures from cell-sized droplets using optical tweezers. Our OptiDIB platform is the first demonstration of optical trapping to precisely construct 3D DIB networks, paving the way for the development of a new generation of modular bio-systems.
Friddin MS, Bolognesi G, Elani Y, et al., 2016, The optical assembly of bilayer networks from cell-sized droplets for synthetic biology, Systems and Synthetic Biology
Friddin MS, Bolognesi G, Elani Y, et al., 2016, Optical tweezers to assemble 2D and 3D droplet interface bilayer networks from cell-sized droplets, EMBL Microfluidics
Bolognesi G, Saito Y, Tyler AI, et al., 2016, Mechanical characterization of ultralow interfacial tension oil-in-water droplets by thermal capillary wave analysis in a microfluidic device., Langmuir, Vol: 32, Pages: 3580-3586, ISSN: 1520-5827
Measurements of the ultralow interfacial tension and surfactant film bending rigidity for micron-sized heptane droplets in AOT-NaCl aqueous solutions were performed in a microfluidic device through the analysis of thermally-driven droplet interface fluctuations. The Fourier spectrum of the stochastic droplet interface displacement was measured through bright-field video microscopy and contour analysis technique. The droplet interfacial tension together with the surfactant film bending rigidity were obtained by fitting the experimental results to the prediction of a capillary wave model. Compared to existing methods for ultralow interfacial tension measurements, this contactless non-destructive all-optical approach has several advantages, such as fast measuring, easy implementation, cost-effectiveness, reduced amount of liquids and integration into lab-on-a-chip devices.
Ces O, Elani Y, Karamdad K, et al., 2016, Novel microfluidic technologies for the bottom-up construction of artificial cells
This talk will outline novel microfluidic strategies for biomembrane engineering that are capable of fabricating vesicles , droplet interface bilayer networks , multisomes  and artificial tissues  where parameters such as membrane asymmetry, membrane curvature, compartment connectivity and individual compartment contents can be controlled. Various bulk methods, such as extrusion, gentle hydration and electroformation, have been synonymous with the formation of lipid vesicles over recent years. However these strategies suffer from significant shortcomings associated with these processes including limited control of vesicle structural parameters such as size, lamellarity, membrane composition and internal contents. To address this technological bottleneck we have developed novel microfluidic platforms to form lipid vesicles in high-Throughput with full control over the composition of both the inner and outer leaflet of the membrane thereby enabling the manufacture of symmetric and asymmetric vesicles. This is achieved by manufacturing microfluidic channels with a step junction, produced by double-layer photolithography, which facilitates the transfer of a W/O emulsion across an oil-water phase boundary and the self-Assembly of a phospholipid bilayer. These platforms are being used to explore the role of asymmetry in biological systems  and study the engineering rules that regulate membrane mediated protein-protein interactions . In addition, these technologies are enabling the construction of biological machines capable of acting as micro-reactors , environmental sensors and smart delivery vehicles  as well as complex multi-compartment artificial cells where the contents and connectivity of each compartment can be controlled. These compartments are separated by biological functional membranes that can facilitate transport between the compartments themselves and between the compartments and external environment. This approach has led to the deve
Friddin MS, Bolognesi G, Elani Y, et al., 2016, Light-driven drag and drop assembly of micron-scale bilayer networks for synthetic biology, Pages: 545-546
We have developed a new method to assemble single- or multi-layered networks of droplet interface bilayers (DIBs) from cell-sized droplets using a single beam optical trap (optical tweezers). The novelty of our approach is the ability to directly trap the microdroplets with the laser and manipulate them in 3D to construct DIB networks of user-defined architectures. Our method does not require a complex optical setup, is versatile, contactless, benefits from both high spatial and temporal resolution, and could set a new paradigm for the assembly of smart, synthetic biosystems.
Bolognesi G, Hargreaves A, Ward AD, et al., 2015, Microfluidic generation and optical manipulation of ultra-low interfacial tension droplets, Conference on Integrated Photonics - Materials, Devices, and Applications III, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, ISSN: 0277-786X
Bolognesi G, Hargreaves A, Ward AD, et al., 2014, Microfluidic generation of monodisperse ultra-low interfacial tension oil droplets in water, RSC Advances, Vol: 5, Pages: 8114-8121, ISSN: 2046-2069
We present a novel microfluidic approach for the generation of monodisperse oil droplets in water with interfacial tensions of the order of 1 μN m−1. Using an oil-in-water emulsion containing the surfactant aerosol OT, heptane, water and sodium chloride under conditions close to the microemulsion phase transition, we actively controlled the surface tension at the liquid–liquid interface within the microfluidic device in order to produce monodisperse droplets. These droplets exhibited high levels of stability with respect to rupture and coalescence rates. Confirmation that the resultant emulsions were in the ultra-low tension regime was determined using real space detection of thermally-induced capillary waves at the droplet interface.
Bolognesi G, Cottin-Bizonne C, Pirat C, 2014, Evidence of slippage breakdown for a superhydrophobic microchannel, Physics of Fluids, Vol: 26, ISSN: 1089-7666
A full characterization of the water flow past a silicon superhydrophobic surface withlongitudinal micro-grooves enclosed in a microfluidic device is presented. Fluorescencemicroscopy images of the flow seeded with fluorescent passive tracers weredigitally processed to measure both the velocity field and the position and shape ofthe liquid-air interfaces at the superhydrophobic surface. The simultaneous access tothe meniscus and velocity profiles allows us to put under a strict test the no-shearboundary condition at the liquid-air interface. Surprisingly, our measurements showthat air pockets in the surface cavities can sustain non-zero interfacial shear stresses,thereby hampering the friction reduction capabilities of the surface. The effects ofthe meniscus position and shape as well as of the liquid-air interfacial friction on thesurface performances are separately assessed and quantified
Bolognesi G, Cottin-Bizonne C, Pirat C, 2014, Evidence of slippage breakdown for a superhydrophobic microchannel, Physics of Fluids, Vol: 26, ISSN: 1089-7666
A full characterization of the water flow past a silicon superhydrophobic surface with longitudinal micro-grooves enclosed in a microfluidic device is presented. Fluorescence microscopy images of the flow seeded with fluorescent passive tracers were digitally processed to measure both the velocity field and the position and shape of the liquid-air interfaces at the superhydrophobic surface. The simultaneous access to the meniscus and velocity profiles allows us to put under a strict test the no-shear boundary condition at the liquid-air interface. Surprisingly, our measurements show that air pockets in the surface cavities can sustain non-zero interfacial shear stresses, thereby hampering the friction reduction capabilities of the surface. The effects of the meniscus position and shape as well as of the liquid-air interfacial friction on the surface performances are separately assessed and quantified.
Gentili D, Bolognesi G, Giacomello A, et al., 2014, Pressure effects on water slippage over silane-coated rough surfaces: pillars and holes, 3rd European Conference on Microfluidics (Mu Flu), Publisher: SPRINGER HEIDELBERG, Pages: 1009-1018, ISSN: 1613-4982
Gentili D, Chinappi M, Bolognesi G, et al., 2013, Water slippage on hydrophobic nanostructured surfaces: molecular dynamics results for different filling levels, MECCANICA, Vol: 48, Pages: 1853-1861, ISSN: 0025-6455
Bolognesi G, Cottin-Bizonne C, Guene EM, et al., 2013, A novel technique for simultaneous velocity and interface profile measurements on micro-structured surfaces, Soft Matter, Vol: 9, Pages: 2239-2244
We present a novel approach which allows simultaneous measurement of the velocity field and the interface profile close to a composite liquid–gas and solid–gas interface. The proposed scheme is the method of choice for the characterization of those flows where the velocity field is highly dependent on the actual shape and position assumed by liquid–gas and liquid–solid interfaces. The new method is based on the digital processing of microscopy images of a flow seeded with fluorescent passive tracers. The relative position and the shape of both liquid–gas and liquid–solid interfaces can be determined with a resolution of few tens of nanometers. The results for the liquid–solid interfaces are also compared to an additional detection method we devised to accurately determine the absolute position of the solid walls.
Hargreaves AL, Kirby AK, Bain CD, et al., 2013, An optical platform for the production, trapping, manipulation and visualization of ultra-low interfacial tension emulsion droplets, Conference on Optical Trapping and Optical Micromanipulation X, Publisher: SPIE-INT SOC OPTICAL ENGINEERING, ISSN: 0277-786X
Gentili D, Chinappi M, Bolognesi G, et al., 2013, Water slippage on hydrophobic nanostructured surfaces: molecular dynamics results for different filling levels, Meccanica, Pages: 1-9
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