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Plasmonic sensing, imaging, and stimulation techniques for neuron studies. Biosens Bioelectron 2021; 182:113150. [PMID: 33774432 DOI: 10.1016/j.bios.2021.113150] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 03/02/2021] [Accepted: 03/04/2021] [Indexed: 12/21/2022]
Abstract
Studies to understand the structure, functions, and electrophysiological properties of neurons have been conducted at the frontmost end of neuroscience. Such studies have led to the active development of high-performance research tools for exploring the neurobiology at the cellular and molecular level. Following this trend, research and application of plasmonics, which is a technology employed in high-sensitivity optical biosensors and high-resolution imaging, is essential for studying neurons, as plasmonic nanoprobes can be used to stimulate specific areas of cells. In this study, three plasmonic modalities were explored as tools to study neurons and their responses: (1) plasmonic sensing of neuronal activities and neuron-related chemicals; (2) performance-improved optical imaging of neurons using plasmonic enhancements; and (3) plasmonic neuromodulations. Through a detailed investigation of these plasmonic modalities and research subjects that can be combined with them, it was confirmed that plasmonic sensing, imaging, and stimulation techniques have the potential to be effectively employed for the study of neurons and understanding their specific molecular activities.
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2
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Ohannesian N, Gunawardhana L, Misbah I, Rakhshandehroo M, Lin SH, Shih WC. Commercial and emerging technologies for cancer diagnosis and prognosis based on circulating tumor exosomes. JPHYS PHOTONICS 2020. [DOI: 10.1088/2515-7647/ab8699] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Abstract
Exosomes are nano-sized extracellular vesicles excreted by mammalian cells that circulate freely in the bloodstream of living organisms. Exosomes have a lipid bilayer that encloses genetic material used in intracellular communication (e.g. double-stranded DNA, micro-RNAs, and messenger RNA). Recent evidence suggests that dysregulation of this genetic content within exosomes has a major role in tumor progression in the surrounding microenvironment. Motivated by this discovery, we focused here on using exosomal biomarkers as a diagnostic and prognostic tool for cancer. In this review, we discuss recently discovered exosome-derived proteomic and genetic biomarkers used in cancer diagnosis and prognosis. Although several genetic biomarkers have been validated for their diagnostic values, proteomic biomarkers are still being actively pursued. We discuss both commercial technologies and emerging technologies for exosome isolation and analysis. Emerging technologies can be classified into optical and non-optical methods. The working principle of each method is briefly discussed as well as advantages and limitations.
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3
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Lednický T, Bonyár A. Large Scale Fabrication of Ordered Gold Nanoparticle-Epoxy Surface Nanocomposites and Their Application as Label-Free Plasmonic DNA Biosensors. ACS APPLIED MATERIALS & INTERFACES 2020; 12:4804-4814. [PMID: 31904921 PMCID: PMC7307838 DOI: 10.1021/acsami.9b20907] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
A robust and scalable technology to fabricate ordered gold nanoparticle arrangements on epoxy substrates is presented. The nanoparticles are synthesized by solid-state dewetting on nanobowled aluminum templates, which are prepared by the selective chemical etching of porous anodic alumina (PAA) grown on an aluminum sheet with controlled anodic oxidation. This flexible fabrication technology provides proper control over the nanoparticle size, shape, and interparticle distance over a large surface area (several cm2), which enables the fine-tuning and optimization of their plasmonic absorption spectra for LSPR and SERS applications between 535 and 625 nm. The nanoparticles are transferred to the surface of epoxy substrates, which are subsequently selectively etched. The resulting nanomushrooms arrangements consist of ordered epoxy nanopillars with flat, disk-shaped nanoparticles on top, and their bulk refractive index sensitivity is between 83 and 108 nm RIU-1. Label-free DNA detection is successfully demonstrated with the sensors by using a 20 base pair long specific DNA sequence from the parasite Giardia lamblia. A red-shift of 6.6 nm in the LSPR absorbance spectrum was detected after the 2 h hybridization with 1 μM target DNA, and the achievable LOD was around 5 nM. The reported plasmonic sensor is one of the first surface AuNP/polymer nanocomposites ever reported for the successful label-free detection of DNA.
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Affiliation(s)
- Tomáš Lednický
- CEITEC - Central
European Institute of Technology, Brno University
of Technology, Brno 612 00, Czech Republic
| | - Attila Bonyár
- Department of Electronics Technology, Budapest
University of Technology and Economics, Budapest H-1111, Hungary
- E-mail: (A.B.)
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4
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Zhu C, Luo X, Espulgar WV, Koyama S, Kumanogoh A, Saito M, Takamatsu H, Tamiya E. Real-Time Monitoring and Detection of Single-Cell Level Cytokine Secretion Using LSPR Technology. MICROMACHINES 2020; 11:E107. [PMID: 31963848 PMCID: PMC7019717 DOI: 10.3390/mi11010107] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/10/2019] [Revised: 01/08/2020] [Accepted: 01/15/2020] [Indexed: 01/14/2023]
Abstract
Cytokine secretion researches have been a main focus of studies among the scientists in the recent decades for its outstanding contribution to clinical diagnostics. Localized surface plasmon resonance (LSPR) technology is one of the conventional methods utilized to analyze these issues, as it could provide fast, label-free and real-time monitoring of biomolecule binding events. However, numerous LSPR-based biosensors in the past are usually utilized to monitor the average performance of cell groups rather than single cells. Meanwhile, the complicated sensor structures will lead to the fabrication and economic budget problems. Thus, in this paper, we report a simple synergistic integration of the cell trapping of microwell chip and gold-capped nanopillar-structured cyclo-olefin-polymer (COP) film for single cell level Interleukin 6 (IL-6) detection. Here, in-situ cytokine secreted from the trapped cell can be directly observed and analyzed through the peak red-shift in the transmittance spectrum. The fabricated device also shows the potential to conduct the real-time monitoring which would greatly help us identify the viability and biological variation of the tested single cell.
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Affiliation(s)
- Chen Zhu
- Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan; (C.Z.); (W.V.E.); (M.S.)
| | - Xi Luo
- Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan; (C.Z.); (W.V.E.); (M.S.)
- AIST-Osaka University Advanced Photonics and Biosensing Open Innovation Laboratory, AIST, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Wilfred Villariza Espulgar
- Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan; (C.Z.); (W.V.E.); (M.S.)
| | - Shohei Koyama
- Immunology Frontier Research Center, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan; (S.K.); (A.K.); (H.T.)
| | - Atsushi Kumanogoh
- Immunology Frontier Research Center, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan; (S.K.); (A.K.); (H.T.)
| | - Masato Saito
- Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan; (C.Z.); (W.V.E.); (M.S.)
- AIST-Osaka University Advanced Photonics and Biosensing Open Innovation Laboratory, AIST, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Hyota Takamatsu
- Immunology Frontier Research Center, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan; (S.K.); (A.K.); (H.T.)
| | - Eiichi Tamiya
- Department of Applied Physics, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan; (C.Z.); (W.V.E.); (M.S.)
- AIST-Osaka University Advanced Photonics and Biosensing Open Innovation Laboratory, AIST, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
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5
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Clementi NC, Cooper CD, Barba LA. Computational nanoplasmonics in the quasistatic limit for biosensing applications. Phys Rev E 2019; 100:063305. [PMID: 31962460 DOI: 10.1103/physreve.100.063305] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Indexed: 06/10/2023]
Abstract
The phenomenon of localized surface plasmon resonance (LSPR) provides high sensitivity in detecting biomolecules through shifts in resonance frequency when a target is present. Computational studies in this field have used the full Maxwell equations with simplified models of a sensor-analyte system, or they neglected the analyte altogether. In the long-wavelength limit, one can simplify the theory via an electrostatics approximation while adding geometrical detail in the sensor and analytes (at moderate computational cost). This work uses the latter approach, expanding the open-source PyGBe code to compute the extinction cross section of metallic nanoparticles in the presence of any target for sensing. The target molecule is represented by a surface mesh, based on its crystal structure. PyGBe is research software for continuum electrostatics, written in python with computationally expensive parts accelerated on GPU hardware, via PyCUDA. It is also accelerated algorithmically via a treecode that offers O(NlogN) computational complexity. These features allow PyGBe to handle problems with half a million boundary elements or more. In this work, we demonstrate the suitability of PyGBe, extended to compute LSPR response in the electrostatic limit, for biosensing applications. Using a model problem consisting of an isolated silver nanosphere in an electric field, our results show grid convergence as 1/N, and accurate computation of the extinction cross section as a function of wavelength (compared with an analytical solution). For a model of a sensor-analyte system, consisting of a spherical silver nanoparticle and a set of bovine serum albumin (BSA) proteins, our results again obtain grid convergence as 1/N (with respect to the Richardson extrapolated value). Computing the LSPR response as a function of wavelength in the presence of BSA proteins captures a redshift of 0.5 nm in the resonance frequency due to the presence of the analytes at 1-nm distance. The final result is a sensitivity study of the biosensor model, obtaining the shift in resonance frequency for various distances between the proteins and the nanoparticle. All results in this paper are fully reproducible, and we have deposited in archival data repositories all the materials needed to run the computations again and recreate the figures. PyGBe is open source under a permissive license and openly developed. Documentation is available at http://pygbe.github.io/pygbe/docs/.
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Affiliation(s)
- Natalia C Clementi
- Department of Mechanical & Aerospace Engineering, The George Washington University, Washington, DC 20052, USA
| | - Christopher D Cooper
- Department of Mechanical Engineering and Centro Científico Tecnológico de Valparaíso, Universidad Técnica Federico Santa María, Valparaíso, Chile
| | - Lorena A Barba
- Department of Mechanical & Aerospace Engineering, The George Washington University, Washington, DC 20052, USA
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6
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Li Y, Lv J, Gu Q, Hu S, Li Z, Jiang X, Ying Y, Si G. Metadevices with Potential Practical Applications. Molecules 2019; 24:E2651. [PMID: 31336634 PMCID: PMC6680820 DOI: 10.3390/molecules24142651] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Revised: 07/10/2019] [Accepted: 07/16/2019] [Indexed: 11/16/2022] Open
Abstract
Metamaterials are "new materials" with different superior physical properties, which have generated great interest and become popular in scientific research. Various designs and functional devices using metamaterials have formed a new academic world. The application concept of metamaterial is based on designing diverse physical structures that can break through the limitations of traditional optical materials and composites to achieve extraordinary material functions. Therefore, metadevices have been widely studied by the academic community recently. Using the properties of metamaterials, many functional metadevices have been well investigated and further optimized. In this article, different metamaterial structures with varying functions are reviewed, and their working mechanisms and applications are summarized, which are near-field energy transfer devices, metamaterial mirrors, metamaterial biosensors, and quantum-cascade detectors. The development of metamaterials indicates that new materials will become an important breakthrough point and building blocks for new research domains, and therefore they will trigger more practical and wide applications in the future.
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Affiliation(s)
- Yafei Li
- College of Information Science and Engineering, Northeastern University, Shenyang 110004, China
| | - Jiangtao Lv
- College of Information Science and Engineering, Northeastern University, Shenyang 110004, China
| | - Qiongchan Gu
- College of Information Science and Engineering, Northeastern University, Shenyang 110004, China
| | - Sheng Hu
- College of Information Science and Engineering, Northeastern University, Shenyang 110004, China
| | - Zhigang Li
- College of Information Science and Engineering, Northeastern University, Shenyang 110004, China
| | - Xiaoxiao Jiang
- College of Information Science and Engineering, Northeastern University, Shenyang 110004, China
| | - Yu Ying
- College of Information & Control Engineering, Shenyang Jianzhu University, Shenyang 110168, China.
| | - Guangyuan Si
- Melbourne Centre for Nanofabrication, Clayton, Victoria 3168, Australia.
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7
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Raghu D, Christodoulides JA, Christophersen M, Liu JL, Anderson GP, Robitaille M, Byers JM, Raphael MP. Nanoplasmonic pillars engineered for single exosome detection. PLoS One 2018; 13:e0202773. [PMID: 30142169 PMCID: PMC6108516 DOI: 10.1371/journal.pone.0202773] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Accepted: 08/08/2018] [Indexed: 11/18/2022] Open
Abstract
Exosomes are secreted nanovesicles which incorporate proteins and nucleic acids, thereby enabling multifunctional pathways for intercellular communication. There is an increasing appreciation of the critical role they play in fundamental processes such as development, wound healing and disease progression, yet because of their heterogeneous molecular content and low concentrations in vivo, their detection and characterization remains a challenge. In this work we combine nano- and microfabrication techniques for the creation of nanosensing arrays tailored toward single exosome detection. Elliptically–shaped nanoplasmonic sensors are fabricated to accommodate at most one exosome and individually imaged in real time, enabling the label-free recording of digital responses in a highly multiplexed geometry. This approach results in a three orders of magnitude sensitivity improvement over previously reported real-time, multiplexed platforms. Each nanosensor is elevated atop a quartz nanopillar, minimizing unwanted nonspecific substrate binding contributions. The approach is validated with the detection of exosomes secreted by MCF7 breast adenocarcinoma cells. We demonstrate the increasingly digital and stochastic nature of the response as the number of subsampled nanosensors is reduced from four hundred to one.
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Affiliation(s)
- Deepa Raghu
- Materials Science and Technology Division, Naval Research Laboratory, Washington, D.C., United States of America
| | - Joseph A. Christodoulides
- Materials Science and Technology Division, Naval Research Laboratory, Washington, D.C., United States of America
| | - Marc Christophersen
- Space Sciences Division, Naval Research Laboratory, Washington, D.C., United States of America
| | - Jinny L. Liu
- Center for Biomolecular Science & Engineering, Naval Research Laboratory, Washington, D.C., United States of America
| | - George P. Anderson
- Center for Biomolecular Science & Engineering, Naval Research Laboratory, Washington, D.C., United States of America
| | - Michael Robitaille
- Materials Science and Technology Division, Naval Research Laboratory, Washington, D.C., United States of America
| | - Jeff M. Byers
- Materials Science and Technology Division, Naval Research Laboratory, Washington, D.C., United States of America
| | - Marc P. Raphael
- Materials Science and Technology Division, Naval Research Laboratory, Washington, D.C., United States of America
- * E-mail:
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8
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Byers JM, Christodoulides JA, Delehanty JB, Raghu D, Raphael MP. Quantifying time-varying cellular secretions with local linear models. Heliyon 2017; 3:e00340. [PMID: 28736751 PMCID: PMC5506887 DOI: 10.1016/j.heliyon.2017.e00340] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2017] [Revised: 05/18/2017] [Accepted: 06/23/2017] [Indexed: 01/09/2023] Open
Abstract
Extracellular protein concentrations and gradients initiate a wide range of cellular responses, such as cell motility, growth, proliferation and death. Understanding inter-cellular communication requires spatio-temporal knowledge of these secreted factors and their causal relationship with cell phenotype. Techniques which can detect cellular secretions in real time are becoming more common but generalizable data analysis methodologies which can quantify concentration from these measurements are still lacking. Here we introduce a probabilistic approach in which local-linear models and the law of mass action are applied to obtain time-varying secreted concentrations from affinity-based biosensor data. We first highlight the general features of this approach using simulated data which contains both static and time-varying concentration profiles. Next we apply the technique to determine concentration of secreted antibodies from 9E10 hybridoma cells as detected using nanoplasmonic biosensors. A broad range of time-dependent concentrations was observed: from steady-state secretions of 230 pM near the cell surface to large transients which reached as high as 56 nM over several minutes and then dissipated.
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Affiliation(s)
- Jeff M Byers
- Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375-5320
| | | | - James B Delehanty
- Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375-5320
| | - Deepa Raghu
- Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375-5320
| | - Marc P Raphael
- Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375-5320
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9
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Raghu D, Christodoulides JA, Delehanty JB, Byers JM, Raphael MP. A Label-free Technique for the Spatio-temporal Imaging of Single Cell Secretions. J Vis Exp 2015. [PMID: 26650542 PMCID: PMC4692743 DOI: 10.3791/53120] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Inter-cellular communication is an integral part of a complex system that helps in maintaining basic cellular activities. As a result, the malfunctioning of such signaling can lead to many disorders. To understand cell-to-cell signaling, it is essential to study the spatial and temporal nature of the secreted molecules from the cell without disturbing the local environment. Various assays have been developed to study protein secretion, however, these methods are typically based on fluorescent probes which disrupt the relevant signaling pathways. To overcome this limitation, a label-free technique is required. In this paper, we describe the fabrication and application of a label-free localized surface plasmon resonance imaging (LSPRi) technology capable of detecting protein secretions from a single cell. The plasmonic nanostructures are lithographically patterned onto a standard glass coverslip and can be excited using visible light on commercially available light microscopes. Only a small fraction of the coverslip is covered by the nanostructures and hence this technique is well suited for combining common techniques such as fluorescence and bright-field imaging. A multidisciplinary approach is used in this protocol which incorporates sensor nanofabrication and subsequent biofunctionalization, binding kinetics characterization of ligand and analyte, the integration of the chip and live cells, and the analysis of the measured signal. As a whole, this technology enables a general label-free approach towards mapping cellular secretions and correlating them with the responses of nearby cells.
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Affiliation(s)
- Deepa Raghu
- Materials Science and Technology, Naval Research Laboratory
| | | | - James B Delehanty
- Center for Bio/Molecular Science and Engineering, Naval Research Laboratory
| | - Jeff M Byers
- Materials Science and Technology, Naval Research Laboratory
| | - Marc P Raphael
- Materials Science and Technology, Naval Research Laboratory;
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10
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Raphael MP, Christodoulides JA, Byers JM, Anderson GP, Liu JL, Turner KB, Goldman ER, Delehanty JB. Optimizing Nanoplasmonic Biosensor Sensitivity with Orientated Single Domain Antibodies. PLASMONICS (NORWELL, MASS.) 2015; 10:1649-1655. [PMID: 26594135 PMCID: PMC4644190 DOI: 10.1007/s11468-015-9969-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 05/08/2015] [Indexed: 06/05/2023]
Abstract
Localized surface plasmon resonance (LSPR) spectroscopy and imaging are emerging biosensor technologies which tout label-free biomolecule detection at the nanoscale and ease of integration with standard microscopy setups. The applicability of these techniques can be limited by the restrictions that surface-conjugated ligands must be both sufficiently small and orientated to meet analyte sensitivity requirements. We demonstrate that orientated single domain antibodies (sdAb) can optimize nanoplasmonic sensitivity by comparing three anti-ricin sdAb constructs to biotin-neutravidin, a model system for small and highly orientated ligand studies. LSPR imaging of electrostatically orientated sdAb exhibited a ricin sensitivity equivalent to that of the biotinylated LSPR biosensors for neutravidin. These results, combined with the facts that sdAb are highly stable and readily produced in bacteria and yeast, build a compelling case for the increased utilization of sdAbs in nanoplasmonic applications.
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Affiliation(s)
- Marc P. Raphael
- />Bioelectronics and Sensing, Code 6363, Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375 USA
| | - Joseph A. Christodoulides
- />Bioelectronics and Sensing, Code 6363, Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375 USA
| | - Jeff M. Byers
- />Bioelectronics and Sensing, Code 6363, Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375 USA
| | - George P. Anderson
- />Center for Bio/Molecular Science and Engineering, Code 6900, Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375 USA
| | - Jinny L. Liu
- />Center for Bio/Molecular Science and Engineering, Code 6900, Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375 USA
| | - Kendrick B. Turner
- />Center for Bio/Molecular Science and Engineering, Code 6900, Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375 USA
| | - Ellen R. Goldman
- />Center for Bio/Molecular Science and Engineering, Code 6900, Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375 USA
| | - James B. Delehanty
- />Center for Bio/Molecular Science and Engineering, Code 6900, Naval Research Laboratory, 4555 Overlook Ave SW, Washington, DC 20375 USA
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11
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Raphael MP, Christodoulides JA, Delehanty JB, Long JP, Byers JM. Quantitative imaging of protein secretions from single cells in real time. Biophys J 2014; 105:602-8. [PMID: 23931308 DOI: 10.1016/j.bpj.2013.06.022] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Revised: 05/24/2013] [Accepted: 06/13/2013] [Indexed: 12/20/2022] Open
Abstract
Protein secretions from individual cells create spatially and temporally varying concentration profiles in the extracellular environment, which guide a wide range of biological processes such as wound healing and angiogenesis. Fluorescent and colorimetric probes for the detection of single cell secretions have time resolutions that range from hours to days, and as a result, little is known about how individual cells may alter their protein secretion rates on the timescale of minutes or seconds. Here, we present a label-free technique based upon nanoplasmonic imaging, which enabled the measurement of individual cell secretions in real time. When applied to the detection of antibody secretions from single hybridoma cells, the enhanced time resolution revealed two modes of secretion: one in which the cell secreted continuously and another in which antibodies were released in concentrated bursts that coincided with minute-long morphological contractions of the cell. From the continuous secretion measurements we determined the local concentration of antibodies at the sensing array closest to the cell and from the bursts we estimated the diffusion constant of the secreted antibodies through the extracellular media. The design also incorporates transmitted light and fluorescence microscopy capabilities for monitoring cellular morphological changes and intracellular fluorescent labels. We anticipate that this technique can be adapted as a general tool for the quantitative study of paracrine signaling in both adherent and nonadherent cell lines.
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Affiliation(s)
- Marc P Raphael
- Materials Science and Technology Division, Naval Research Laboratory, Washington DC, USA.
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12
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Bhagawati M, You C, Piehler J. Quantitative real-time imaging of protein-protein interactions by LSPR detection with micropatterned gold nanoparticles. Anal Chem 2013; 85:9564-71. [PMID: 24016060 DOI: 10.1021/ac401673e] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Localized surface plasmon resonance (LSPR) offers powerful means for sensitive label-free detection of protein-protein interactions in a highly multiplexed format. We have here established self-assembly and surface modification of plasmonic nanostructures on solid support suitable for quantitative protein-protein interaction analysis by spectroscopic and microscopic LSPR detection. These architectures were obtained by layer-by-layer assembly via electrostatic attraction. Gold nanoparticles (AuNP) were adsorbed on a biocompatible amine-terminated poly(ethylene glycol) (PEG) polymer brush and further functionalized by poly-l-lysine graft PEG (PLL-PEG) copolymers. Stable yet reversible protein immobilization was achieved via tris(nitrilotriacetic acid) groups incorporated into the PLL-PEG coating. Thus, site-specific immobilization of His-tagged proteins via complexed Ni(II) ions was achieved. Functional protein immobilization on the surface was confirmed by real-time detection of LSPR scattering by reflectance spectroscopy. Association and dissociation rate constants obtained for a reversible protein-protein interaction were in good agreement with the data obtained by other surface-sensitive detection techniques. For spatially resolved detection, AuNP were assembled into micropatterns by means of photolithographic uncaging of surface amines. LSPR imaging of reversible protein-protein interactions was possible in a conventional wide field microscope, yielding detection limits of ∼30 protein molecules within a diffraction-limited surface area.
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Affiliation(s)
- Maniraj Bhagawati
- Department of Biology, University of Osnabrück , Barbarastrasse 11, 49076 Osnabrück, Germany
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