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Walter V, Bi D, Salehi-Reyhani A, Deng Y. Real-time signal processing via chemical reactions for a microfluidic molecular communication system. Nat Commun 2023; 14:7188. [PMID: 37938589 PMCID: PMC10632502 DOI: 10.1038/s41467-023-42885-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Accepted: 10/24/2023] [Indexed: 11/09/2023] Open
Abstract
Signal processing over the molecular domain is critical for analysing, modifying, and synthesising chemical signals in molecular communication systems. However, the lack of chemical signal processing blocks and the wide use of electronic devices to process electrical signals in existing molecular communication platforms can hardly meet the biocompatible, non-invasive, and size-miniaturised requirements of applications in various fields, e.g., medicine, biology, and environment sciences. To tackle this, here we design and construct a liquid-based microfluidic molecular communication platform for performing chemical concentration signal processing and digital signal transmission over distances. By specifically designing chemical reactions and microfluidic geometry, the transmitter of our platform is capable of shaping the emitted signals, and the receiver is able to threshold, amplify, and detect the chemical signals after propagation. By encoding bit information into the concentration of sodium hydroxide, we demonstrate that our platform can achieve molecular signal modulation and demodulation functionalities, and reliably transmit text messages over long distances. This platform is further optimised to maximise data rate while minimising communication error. The presented methodology for real-time chemical signal processing can enable the implementation of signal processing units in biological settings and then unleash its potential for interdisciplinary applications.
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Affiliation(s)
- Vivien Walter
- Department of Engineering, King's College London, London, WC2R 2LS, UK
| | - Dadi Bi
- Department of Engineering, King's College London, London, WC2R 2LS, UK
| | - Ali Salehi-Reyhani
- Department of Surgery and Cancer, Imperial College London, London, W12 0HS, UK
- Institute for Molecular Science and Engineering, Imperial College London, London, SW7 2AZ, UK
| | - Yansha Deng
- Department of Engineering, King's College London, London, WC2R 2LS, UK.
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2
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Supramaniam P, Wang Z, Chatzimichail S, Parperis C, Kumar A, Ho V, Ces O, Salehi-Reyhani A. Measuring Encapsulation Efficiency in Cell-Mimicking Giant Unilamellar Vesicles. ACS Synth Biol 2023; 12:1227-1238. [PMID: 36977193 PMCID: PMC10127275 DOI: 10.1021/acssynbio.2c00684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/30/2023]
Abstract
One of the main drivers within the field of bottom-up synthetic biology is to develop artificial chemical machines, perhaps even living systems, that have programmable functionality. Numerous toolkits exist to generate giant unilamellar vesicle-based artificial cells. However, methods able to quantitatively measure their molecular constituents upon formation is an underdeveloped area. We report an artificial cell quality control (AC/QC) protocol using a microfluidic-based single-molecule approach, enabling the absolute quantification of encapsulated biomolecules. While the measured average encapsulation efficiency was 11.4 ± 6.8%, the AC/QC method allowed us to determine encapsulation efficiencies per vesicle, which varied significantly from 2.4 to 41%. We show that it is possible to achieve a desired concentration of biomolecule within each vesicle by commensurate compensation of its concentration in the seed emulsion. However, the variability in encapsulation efficiency suggests caution is necessary when using such vesicles as simplified biological models or standards.
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Affiliation(s)
| | - Zibo Wang
- Department of Surgery & Cancer, Imperial College London, London W12 0HS, U.K
- Department of Chemistry, King's College London, London SE1 1DB, U.K
| | | | - Christopher Parperis
- Department of Chemistry, Imperial College London, London W12 0BZ, U.K
- Department of Chemistry, King's College London, London SE1 1DB, U.K
| | - Aditi Kumar
- Department of Chemistry, Imperial College London, London W12 0BZ, U.K
| | - Vanessa Ho
- Department of Chemistry, Imperial College London, London W12 0BZ, U.K
| | - Oscar Ces
- Department of Chemistry, Imperial College London, London W12 0BZ, U.K
- fabriCELL, Imperial College London, London SW7 2AZ, U.K
| | - Ali Salehi-Reyhani
- Department of Surgery & Cancer, Imperial College London, London W12 0HS, U.K
- fabriCELL, Imperial College London, London SW7 2AZ, U.K
- Institute for Molecular Science and Engineering, Imperial College London, London SW7 2AZ, U.K
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3
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Ho S, Ezeorah C, Chari S, Salehi-Reyhani A, Britovsek G. Monitoring Light‐Driven Oxygen Insertion Reactions into Metal Carbon Bonds by LED‐NMR Spectroscopy. CHEMPHOTOCHEM 2023. [DOI: 10.1002/cptc.202200290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/16/2023]
Affiliation(s)
- Sarah Ho
- Imperial College London Chemistry UNITED KINGDOM
| | | | - Suviti Chari
- Imperial College London Chemistry UNITED KINGDOM
| | | | - George Britovsek
- Imperial College London Chemistry MSRH80 WoodlaneWhite City W12 0BZ London UNITED KINGDOM
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4
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Chatzimichail S, Supramaniam P, Salehi-Reyhani A. Absolute Quantification of Protein Copy Number in Single Cells With Immunofluorescence Microscopy Calibrated Using Single-Molecule Microarrays. Anal Chem 2021; 93:6656-6664. [PMID: 33876929 DOI: 10.1021/acs.analchem.0c05177] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Great strides toward routine single-cell analyses have been made over the last decade, particularly in the field of transcriptomics. For proteomics, amplification is not currently possible and has necessitated the development of ultrasensitive platforms capable of performing such analyses on single cells. These platforms are improving in terms of throughput and multiplexability but still fall short in relation to more established methods such as fluorescence microscopy. However, microscopy methods rely on fluorescence intensity as a proxy for protein abundance and are not currently capable of reporting this in terms of an absolute copy number. Here, a microfluidic implementation of single-molecule microarrays for single-cell analysis is assessed in its ability to calibrate fluorescence microscopy data. We show that the equivalence of measurements of the steady-state distribution of protein abundance to single-molecule microarray data can be exploited to pave the way for absolute quantitation by fluorescence and immunofluorescence microscopy. The methods presented have been developed using GFP but are extendable to other proteins and other biomolecules of interest.
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Affiliation(s)
| | | | - Ali Salehi-Reyhani
- Department of Surgery & Cancer, Imperial College London, London W12 0HS, U.K
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5
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Chatzimichail S, Rahimi F, Saifuddin A, Surman AJ, Taylor-Robinson SD, Salehi-Reyhani A. Hand-portable HPLC with broadband spectral detection enables analysis of complex polycyclic aromatic hydrocarbon mixtures. Commun Chem 2021; 4:17. [PMID: 36697529 PMCID: PMC9814556 DOI: 10.1038/s42004-021-00457-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2020] [Accepted: 01/19/2021] [Indexed: 01/28/2023] Open
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are considered priority hazardous substances due to their carcinogenic activity and risk to public health. Strict regulations are in place limiting their release into the environment, but enforcement is hampered by a lack of adequate field-testing procedure, instead relying on sending samples to centralised analytical facilities. Reliably monitoring levels of PAHs in the field is a challenge, owing to the lack of field-deployable analytical methods able to separate, identify, and quantify the complex mixtures in which PAHs are typically observed. Here, we report the development of a hand-portable system based on high-performance liquid chromatography incorporating a spectrally wide absorption detector, capable of fingerprinting PAHs based on their characteristic spectral absorption profiles: identifying 100% of the 24 PAHs tested, including full coverage of the United States Environmental Protection Agency priority pollutant list. We report unsupervised methods to exploit these new capabilities for feature detection and identification, robust enough to detect and classify co-eluting and hidden peaks. Identification is fully independent of their characteristic retention times, mitigating matrix effects which can preclude reliable determination of these analytes in challenging samples. We anticipate the platform to enable more sophisticated analytical measurements, supporting real-time decision making in the field.
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Affiliation(s)
- Stelios Chatzimichail
- grid.7445.20000 0001 2113 8111Department of Surgery and Cancer, Imperial College London, London, W12 0HS UK
| | - Faraz Rahimi
- grid.7445.20000 0001 2113 8111Department of Surgery and Cancer, Imperial College London, London, W12 0HS UK ,grid.13097.3c0000 0001 2322 6764Department of Chemistry, King’s College London, London, SE1 1DB UK
| | - Aliyah Saifuddin
- grid.7445.20000 0001 2113 8111Department of Surgery and Cancer, Imperial College London, London, W12 0HS UK ,grid.13097.3c0000 0001 2322 6764Department of Chemistry, King’s College London, London, SE1 1DB UK
| | - Andrew J. Surman
- grid.13097.3c0000 0001 2322 6764Department of Chemistry, King’s College London, London, SE1 1DB UK
| | - Simon D. Taylor-Robinson
- grid.7445.20000 0001 2113 8111Department of Surgery and Cancer, Imperial College London, London, W12 0HS UK
| | - Ali Salehi-Reyhani
- grid.7445.20000 0001 2113 8111Department of Surgery and Cancer, Imperial College London, London, W12 0HS UK ,grid.7445.20000 0001 2113 8111Institute of Molecular Sciences & Engineering, Imperial College London, London, SW7 2AZ UK
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6
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Abstract
A major trend in analytical chemistry is the miniaturization of laboratory instrumentation. We report a pump requiring no power to operate based on the controlled expansion of a pre-pressurised gas for use in portable applications of high-performance liquid chromatography. The performance of the gas pump is characterised and integrated into a compact liquid chromatography system capable of isocratic separations integrating an LED-based UV-absorption detector. The system weighed 6.7 kg when the mobile phase reservoir was fully charged with 150 mL solvent and included an on-board computer to control the system and analyse data. We characterise the flow-rate through chromatography columns with a variety of geometries and packing materials for a range of pressures up to 150 bar. The maximum variation in flow rate was measured to be 6.5 nL min-1, limited by the resolution of the flow detector. All tests were made on battery power and results are a mixture of those made in the laboratory and in the field. Additionally, we performed a series of 1 m drop tests on the device and show the system's high tolerance to mechanical shocks during operation in the field.
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Affiliation(s)
- Stelios Chatzimichail
- Department of Chemistry, King's College London, Britannia House, 7 Trinity Street, London, SE1 1DB, UK.
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7
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Supramaniam P, Ces O, Salehi-Reyhani A. Microfluidics for Artificial Life: Techniques for Bottom-Up Synthetic Biology. Micromachines (Basel) 2019; 10:E299. [PMID: 31052344 PMCID: PMC6562628 DOI: 10.3390/mi10050299] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 04/24/2019] [Accepted: 04/26/2019] [Indexed: 01/08/2023]
Abstract
Synthetic biology is a rapidly growing multidisciplinary branch of science that exploits the advancement of molecular and cellular biology. Conventional modification of pre-existing cells is referred to as the top-down approach. Bottom-up synthetic biology is an emerging complementary branch that seeks to construct artificial cells from natural or synthetic components. One of the aims in bottom-up synthetic biology is to construct or mimic the complex pathways present in living cells. The recent, and rapidly growing, application of microfluidics in the field is driven by the central tenet of the bottom-up approach-the pursuit of controllably generating artificial cells with precisely defined parameters, in terms of molecular and geometrical composition. In this review we survey conventional methods of artificial cell synthesis and their limitations. We proceed to show how microfluidic approaches have been pivotal in overcoming these limitations and ushering in a new generation of complexity that may be imbued in artificial cells and the milieu of applications that result.
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Affiliation(s)
- Pashiini Supramaniam
- Department of Chemistry, White City Campus, Imperial College London, London SW7 2AZ, UK.
| | - Oscar Ces
- Department of Chemistry, White City Campus, Imperial College London, London SW7 2AZ, UK.
- FabriCELL, Imperial College London, London SW7 2AZ, UK.
| | - Ali Salehi-Reyhani
- FabriCELL, Imperial College London, London SW7 2AZ, UK.
- Department of Chemistry, King's College London, Britannia House, London SE1 1DB, UK.
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8
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Friddin MS, Bolognesi G, Salehi-Reyhani A, Ces O, Elani Y. Direct manipulation of liquid ordered lipid membrane domains using optical traps. Commun Chem 2019. [DOI: 10.1038/s42004-018-0101-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
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9
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Barlow NE, Kusumaatmaja H, Salehi-Reyhani A, Brooks N, Barter LMC, Flemming AJ, Ces O. Measuring bilayer surface energy and curvature in asymmetric droplet interface bilayers. J R Soc Interface 2018; 15:rsif.2018.0610. [PMID: 30464059 PMCID: PMC6283991 DOI: 10.1098/rsif.2018.0610] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Accepted: 10/23/2018] [Indexed: 11/12/2022] Open
Abstract
For the past decade, droplet interface bilayers (DIBs) have had an increased prevalence in biomolecular and biophysical literature. However, much of the underlying physics of these platforms is poorly characterized. To further our understanding of these structures, lipid membrane tension on DIB membranes is measured by analysing the equilibrium shape of asymmetric DIBs. To this end, the morphology of DIBs is explored for the first time using confocal laser scanning fluorescence microscopy. The experimental results confirm that, in accordance with theory, the bilayer interface of a volume-asymmetric DIB is curved towards the smaller droplet and a lipid-asymmetric DIB is curved towards the droplet with the higher monolayer surface tension. Moreover, the DIB shape can be exploited to measure complex bilayer surface energies. In this study, the bilayer surface energy of DIBs composed of lipid mixtures of phosphatidylgylcerol (PG) and phosphatidylcholine are shown to increase linearly with PG concentrations up to 25%. The assumption that DIB bilayer area can be geometrically approximated as a spherical cap base is also tested, and it is discovered that the bilayer curvature is negligible for most practical symmetric or asymmetric DIB systems with respect to bilayer area.
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Affiliation(s)
- Nathan E Barlow
- Department of Chemistry, Imperial College London, London SW7 2AZ, UK.,Institute of Chemical Biology, Imperial College London, London SW7 2AZ, UK
| | - Halim Kusumaatmaja
- Department of Physics, Durham University, South Road, Durham DH1 3LE, UK
| | - Ali Salehi-Reyhani
- Department of Chemistry, Imperial College London, London SW7 2AZ, UK.,Institute of Chemical Biology, Imperial College London, London SW7 2AZ, UK.,FABRICELL, Imperial College London, London SW7 2AZ, UK
| | - Nick Brooks
- Department of Chemistry, Imperial College London, London SW7 2AZ, UK.,Institute of Chemical Biology, Imperial College London, London SW7 2AZ, UK
| | - Laura M C Barter
- Department of Chemistry, Imperial College London, London SW7 2AZ, UK.,Institute of Chemical Biology, Imperial College London, London SW7 2AZ, UK
| | - Anthony J Flemming
- Syngenta, Jealott's Hill International Research Centre, Bracknell RG42 6EY, UK
| | - Oscar Ces
- Department of Chemistry, Imperial College London, London SW7 2AZ, UK .,Institute of Chemical Biology, Imperial College London, London SW7 2AZ, UK.,FABRICELL, Imperial College London, London SW7 2AZ, UK
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10
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Chatzimichail S, Supramaniam P, Ces O, Salehi-Reyhani A. Micropatterning of planar metal electrodes by vacuum filling microfluidic channel geometries. Sci Rep 2018; 8:14380. [PMID: 30258167 PMCID: PMC6158193 DOI: 10.1038/s41598-018-32706-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 09/13/2018] [Indexed: 11/09/2022] Open
Abstract
We present a simple, facile method to micropattern planar metal electrodes defined by the geometry of a microfluidic channel network template. By introducing aqueous solutions of metal into reversibly adhered PDMS devices by desiccation instead of flow, we are able to produce difficult to pattern "dead end" or discontinuous features with ease. We characterize electrodes fabricated using this method and perform electrical lysis of mammalian cancer cells and demonstrate their use as part of an antibody capture assay for GFP. Cell lysis in microwell arrays is achieved using the electrodes and the protein released is detected using an antibody microarray. We show how the template channels used as part of the workflow for patterning the electrodes may be produced using photolithography-free methods, such as laser micromachining and PDMS master moulding, and demonstrate how the use of an immiscible phase may be employed to create electrode spacings on the order of 25-50 μm, that overcome the current resolution limits of such methods. This work demonstrates how the rapid prototyping of electrodes for use in total analysis systems can be achieved on the bench with little or no need for centralized facilities.
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Affiliation(s)
- Stelios Chatzimichail
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, London, W12 0BZ, UK
- Institute of Chemical Biology, Molecular Sciences Research Hub, Imperial College London, London, W12 0BZ, UK
| | - Pashiini Supramaniam
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, London, W12 0BZ, UK
- Institute of Chemical Biology, Molecular Sciences Research Hub, Imperial College London, London, W12 0BZ, UK
| | - Oscar Ces
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, London, W12 0BZ, UK
- Institute of Chemical Biology, Molecular Sciences Research Hub, Imperial College London, London, W12 0BZ, UK
- fabriCELL, Molecular Sciences Research Hub, Imperial College London, London, W12 0BZ, UK
| | - Ali Salehi-Reyhani
- Department of Chemistry, Molecular Sciences Research Hub, Imperial College London, London, W12 0BZ, UK.
- Institute of Chemical Biology, Molecular Sciences Research Hub, Imperial College London, London, W12 0BZ, UK.
- fabriCELL, Molecular Sciences Research Hub, Imperial College London, London, W12 0BZ, UK.
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11
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Trantidou T, Friddin MS, Salehi-Reyhani A, Ces O, Elani Y. Droplet microfluidics for the construction of compartmentalised model membranes. Lab Chip 2018; 18:2488-2509. [PMID: 30066008 DOI: 10.1039/c8lc00028j] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
The design of membrane-based constructs with multiple compartments is of increasing importance given their potential applications as microreactors, as artificial cells in synthetic-biology, as simplified cell models, and as drug delivery vehicles. The emergence of droplet microfluidics as a tool for their construction has allowed rapid scale-up in generation throughput, scale-down of size, and control over gross membrane architecture. This is true on several levels: size, level of compartmentalisation and connectivity of compartments can all be programmed to various degrees. This tutorial review explains and explores the reasons behind this. We discuss microfluidic strategies for the generation of a family of compartmentalised systems that have lipid membranes as the basic structural motifs, where droplets are either the fundamental building blocks, or are precursors to the membrane-bound compartments. We examine the key properties associated with these systems (including stability, yield, encapsulation efficiency), discuss relevant device fabrication technologies, and outline the technical challenges. In doing so, we critically review the state-of-play in this rapidly advancing field.
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Affiliation(s)
- T Trantidou
- Department of Chemistry, Imperial College London, London, SW7 2AZ, UK.
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12
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Chatzimichail S, Supramaniam P, Ces O, Salehi-Reyhani A. Counting Proteins in Single Cells with Addressable Droplet Microarrays. J Vis Exp 2018. [PMID: 30035757 DOI: 10.3791/56110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Often cellular behavior and cellular responses are analyzed at the population level where the responses of many cells are pooled together as an average result masking the rich single cell behavior within a complex population. Single cell protein detection and quantification technologies have made a remarkable impact in recent years. Here we describe a practical and flexible single cell analysis platform based on addressable droplet microarrays. This study describes how the absolute copy numbers of target proteins may be measured with single cell resolution. The tumor suppressor p53 is the most commonly mutated gene in human cancer, with more than 50% of total cancer cases exhibiting a non-healthy p53 expression pattern. The protocol describes steps to create 10 nL droplets within which single human cancer cells are isolated and the copy number of p53 protein is measured with single molecule resolution to precisely determine the variability in expression. The method may be applied to any cell type including primary material to determine the absolute copy number of any target proteins of interest.
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Affiliation(s)
| | | | - Oscar Ces
- Institute of Chemical Biology, Department of Chemistry, Imperial College London
| | - Ali Salehi-Reyhani
- Institute of Chemical Biology, Department of Chemistry, Imperial College London;
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13
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Bolognesi G, Friddin MS, Salehi-Reyhani A, Barlow NE, Brooks NJ, Ces O, Elani Y. Sculpting and fusing biomimetic vesicle networks using optical tweezers. Nat Commun 2018; 9:1882. [PMID: 29760422 PMCID: PMC5951844 DOI: 10.1038/s41467-018-04282-w] [Citation(s) in RCA: 93] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 04/10/2018] [Indexed: 11/16/2022] Open
Abstract
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. Assembly of higher-order artificial vesicles can unlock new applications. Here, the authors use optical tweezers to construct user-defined 2D and 3D architectures of chemically distinct vesicles and demonstrate inter-vesicle communication and light-enabled compartment merging.
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Affiliation(s)
- Guido Bolognesi
- Department of Chemical Engineering, Loughborough University, Loughborough, LE11 3TU, UK
| | - Mark S Friddin
- Department of Chemistry, Imperial College London, Exhibition Road, London, SW7 2AZ, UK
| | - Ali Salehi-Reyhani
- Department of Chemistry, Imperial College London, Exhibition Road, London, SW7 2AZ, UK.,Institute of Chemical Biology, Imperial College London, Exhibition Road, London, SW7 2AZ, UK.,FABRICELL, Imperial College London, Exhibition Road, London, SW7 2AZ, UK
| | - Nathan E Barlow
- Department of Chemistry, Imperial College London, Exhibition Road, London, SW7 2AZ, UK
| | - Nicholas J Brooks
- Department of Chemistry, Imperial College London, Exhibition Road, London, SW7 2AZ, UK.,Institute of Chemical Biology, Imperial College London, Exhibition Road, London, SW7 2AZ, UK
| | - Oscar Ces
- Department of Chemistry, Imperial College London, Exhibition Road, London, SW7 2AZ, UK. .,Institute of Chemical Biology, Imperial College London, Exhibition Road, London, SW7 2AZ, UK. .,FABRICELL, Imperial College London, Exhibition Road, London, SW7 2AZ, UK.
| | - Yuval Elani
- Department of Chemistry, Imperial College London, Exhibition Road, London, SW7 2AZ, UK. .,Institute of Chemical Biology, Imperial College London, Exhibition Road, London, SW7 2AZ, UK. .,FABRICELL, Imperial College London, Exhibition Road, London, SW7 2AZ, UK.
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14
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Salehi-Reyhani A. Evaluating single molecule detection methods for microarrays with high dynamic range for quantitative single cell analysis. Sci Rep 2017; 7:17957. [PMID: 29263350 PMCID: PMC5738400 DOI: 10.1038/s41598-017-18303-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 12/07/2017] [Indexed: 11/09/2022] Open
Abstract
Single molecule microarrays have been used in quantitative proteomics, in particular, single cell analysis requiring high sensitivity and ultra-low limits of detection. In this paper, several image analysis methods are evaluated for their ability to accurately enumerate single molecules bound to a microarray spot. Crucially, protein abundance in single cells can vary significantly and may span several orders of magnitude. This poses a challenge to single molecule image analysis. In order to quantitatively assess the performance of each method, synthetic image datasets are generated with known ground truth whereby the number of single molecules varies over 5 orders of magnitude with a range of signal to noise ratios. Experiments were performed on synthetic datasets whereby the number of single molecules per spot corresponds to realistic single cell distributions whose ground truth summary statistics are known. The methods of image analysis are assessed in their ability to accurately estimate the distribution parameters. It is shown that super-resolution image analysis methods can significantly improve counting accuracy and better cope with single molecule congestion. The results highlight the challenge posed by quantitative single cell analysis and the implications to performing such analyses using microarray based approaches are discussed.
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Affiliation(s)
- Ali Salehi-Reyhani
- Department Chemistry, Institute of Chemical Biology, Imperial College London, London, SW7 2AZ, UK.
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15
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Abstract
Living cells are hugely complex chemical systems composed of a milieu of distinct chemical species (including DNA, proteins, lipids, and metabolites) interconnected with one another through a vast web of interactions: this complexity renders the study of cell biology in a quantitative and systematic manner a difficult task. There has been an increasing drive towards the utilization of artificial cells as cell mimics to alleviate this, a development that has been aided by recent advances in artificial cell construction. Cell mimics are simplified cell-like structures, composed from the bottom-up with precisely defined and tunable compositions. They allow specific facets of cell biology to be studied in isolation, in a simplified environment where control of variables can be achieved without interference from a living and responsive cell. This mini-review outlines the core principles of this approach and surveys recent key investigations that use cell mimics to address a wide range of biological questions. It will also place the field in the context of emerging trends, discuss the associated limitations, and outline future directions of the field. Impact statement Recent years have seen an increasing drive to construct cell mimics and use them as simplified experimental models to replicate and understand biological phenomena in a well-defined and controlled system. By summarizing the advances in this burgeoning field, and using case studies as a basis for discussion on the limitations and future directions of this approach, it is hoped that this minireview will spur others in the experimental biology community to use artificial cells as simplified models with which to probe biological systems.
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Affiliation(s)
| | - Oscar Ces
- Department of Chemistry, Imperial College London, London SW7 2AZ, UK
| | - Yuval Elani
- Department of Chemistry, Imperial College London, London SW7 2AZ, UK
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16
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Salehi-Reyhani A, Gesellchen F, Mampallil D, Wilson R, Reboud J, Ces O, Willison KR, Cooper JM, Klug DR. Chemical-Free Lysis and Fractionation of Cells by Use of Surface Acoustic Waves for Sensitive Protein Assays. Anal Chem 2015; 87:2161-9. [DOI: 10.1021/ac5033758] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
| | - Frank Gesellchen
- Division
of Biomedical Engineering, School of Engineering, University of Glasgow, Oakfield Avenue, Glasgow G12 8LT, United Kingdom
| | - Dileep Mampallil
- Division
of Biomedical Engineering, School of Engineering, University of Glasgow, Oakfield Avenue, Glasgow G12 8LT, United Kingdom
| | - Rab Wilson
- Division
of Biomedical Engineering, School of Engineering, University of Glasgow, Oakfield Avenue, Glasgow G12 8LT, United Kingdom
| | - Julien Reboud
- Division
of Biomedical Engineering, School of Engineering, University of Glasgow, Oakfield Avenue, Glasgow G12 8LT, United Kingdom
| | | | | | - Jonathan M. Cooper
- Division
of Biomedical Engineering, School of Engineering, University of Glasgow, Oakfield Avenue, Glasgow G12 8LT, United Kingdom
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Salehi-Reyhani A, Burgin E, Ces O, Willison KR, Klug DR. Addressable droplet microarrays for single cell protein analysis. Analyst 2014; 139:5367-74. [DOI: 10.1039/c4an01208a] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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18
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Burgin E, Salehi-Reyhani A, Barclay M, Brown A, Kaplinsky J, Novakova M, Neil MAA, Ces O, Willison KR, Klug DR. Absolute quantification of protein copy number using a single-molecule-sensitive microarray. Analyst 2014; 139:3235-44. [DOI: 10.1039/c4an00091a] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Salehi-Reyhani A, Sharma S, Burgin E, Barclay M, Cass A, Neil MAA, Ces O, Willison KR, Klug DR, Brown A, Novakova M. Scaling advantages and constraints in miniaturized capture assays for single cell protein analysis. Lab Chip 2013; 13:2066-74. [PMID: 23592024 DOI: 10.1039/c3lc41388h] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Measuring protein expression in single cells is the basis of single cell proteomics. The sensitivity and dynamic range of a single cell immunoassay should ideally be such that proteins that are expressed between 1-10(6) copies per cell can be detected and counted. We have investigated the effect of miniaturizing antibody microarrays by reducing capture spot sizes from 100 μm to 15 μm using dip-pen nanolithography. We demonstrate that protocols developed for printing and passivating antibody capture spots using conventional pin-based contact printing can be directly transferred to dip-pen lithography whilst retaining the capture activity per unit area. Using a simple kinetic model, we highlight how the limit of detection and dynamic range of a sandwich immunoassay, respectively, increase and decrease when spot size is reduced. However, we show that reducing spot size is more effective than increasing assay chamber volume when seeking to multiplex such a microfluidic immunoassay. Although we make particular reference to single cell microfluidic immunoassays, the topics discussed here are applicable to capture assays in general.
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Affiliation(s)
- Ali Salehi-Reyhani
- Proxomics, Institute of Chemical Biology, Imperial College London, London, SW7 2AZ, UK.
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Salehi-Reyhani A, Kaplinsky J, Burgin E, Novakova M, deMello AJ, Templer RH, Parker P, Neil MAA, Ces O, French P, Willison KR, Klug D. A first step towards practical single cell proteomics: a microfluidic antibody capture chip with TIRF detection. Lab Chip 2011; 11:1256-61. [PMID: 21347466 DOI: 10.1039/c0lc00613k] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
We have developed a generic platform to undertake the analysis of protein copy number from single cells. The approach described here is 'all-optical' whereby single cells are manipulated into separate analysis chambers using an optical trap; single cells are lysed by a shock wave caused by laser-induced microcavitation, and the protein released from a single cell is measured by total internal reflection microscopy as it is bound to micro-printed antibody spots within the device. The platform was tested using GFP transfected cells and the relative precision of the measurement method was determined to be 88%. Single cell measurements were also made on a breast cancer cell line to measure the relative levels of unlabelled human tumour suppressor protein p53 using a chip incorporating an antibody sandwich assay format. These results suggest that this is a viable method for measuring relative protein levels in single cells.
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Affiliation(s)
- Ali Salehi-Reyhani
- Single Cell Proteomics Project, Institute of Chemical Biology, Imperial College London, Exhibition Road, London SW7 2AZ, UK.
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