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Seo D, Seong S, Kim H, Oh HS, Lee JH, Kim H, Kim YO, Maeda S, Chikami S, Hayashi T, Noh J. Molecular Self-Assembly and Adsorption Structure of 2,2'-Dipyrimidyl Disulfides on Au(111) Surfaces. Molecules 2024; 29:846. [PMID: 38398598 PMCID: PMC10892263 DOI: 10.3390/molecules29040846] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2024] [Revised: 02/08/2024] [Accepted: 02/12/2024] [Indexed: 02/25/2024] Open
Abstract
The effects of solution concentration and pH on the formation and surface structure of 2-pyrimidinethiolate (2PymS) self-assembled monolayers (SAMs) on Au(111) via the adsorption of 2,2'-dipyrimidyl disulfide (DPymDS) were examined using scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS). STM observations revealed that the formation and structural order of 2PymS SAMs were markedly influenced by the solution concentration and pH. 2PymS SAMs formed in a 0.01 mM ethanol solution were mainly composed of a more uniform and ordered phase compared with those formed in 0.001 mM or 1 mM solutions. SAMs formed in a 0.01 mM solution at pH 2 were composed of a fully disordered phase with many irregular and bright aggregates, whereas SAMs formed at pH 7 had small ordered domains and many bright islands. As the solution pH increased from pH 7 to pH 12, the surface morphology of 2PymS SAMs remarkably changed from small ordered domains to large ordered domains, which can be described as a (4√2 × 3)R51° packing structure. XPS measurements clearly showed that the adsorption of DPymDS on Au(111) resulted in the formation of 2PymS (thiolate) SAMs via the cleavage of the disulfide (S-S) bond in DPymDS, and most N atoms in the pyrimidine rings existed in the deprotonated form. The results herein will provide a new insight into the molecular self-assembly behaviors and adsorption structures of DPymDS molecules on Au(111) depending on solution concentration and pH.
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Affiliation(s)
- Dongjin Seo
- Department of Chemistry, Hanyang University, Seoul 04763, Republic of Korea; (D.S.); (S.S.); (H.K.); (H.S.O.); (J.H.L.); (H.K.); (Y.O.K.)
| | - Sicheon Seong
- Department of Chemistry, Hanyang University, Seoul 04763, Republic of Korea; (D.S.); (S.S.); (H.K.); (H.S.O.); (J.H.L.); (H.K.); (Y.O.K.)
| | - Haeri Kim
- Department of Chemistry, Hanyang University, Seoul 04763, Republic of Korea; (D.S.); (S.S.); (H.K.); (H.S.O.); (J.H.L.); (H.K.); (Y.O.K.)
| | - Hyun Su Oh
- Department of Chemistry, Hanyang University, Seoul 04763, Republic of Korea; (D.S.); (S.S.); (H.K.); (H.S.O.); (J.H.L.); (H.K.); (Y.O.K.)
| | - Jun Hyeong Lee
- Department of Chemistry, Hanyang University, Seoul 04763, Republic of Korea; (D.S.); (S.S.); (H.K.); (H.S.O.); (J.H.L.); (H.K.); (Y.O.K.)
| | - Hongki Kim
- Department of Chemistry, Hanyang University, Seoul 04763, Republic of Korea; (D.S.); (S.S.); (H.K.); (H.S.O.); (J.H.L.); (H.K.); (Y.O.K.)
| | - Yeon O Kim
- Department of Chemistry, Hanyang University, Seoul 04763, Republic of Korea; (D.S.); (S.S.); (H.K.); (H.S.O.); (J.H.L.); (H.K.); (Y.O.K.)
| | - Shoichi Maeda
- Department of Materials Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, Yokohama 226-8503, Japan; (S.M.); (S.C.)
| | - Shunta Chikami
- Department of Materials Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, Yokohama 226-8503, Japan; (S.M.); (S.C.)
| | - Tomohiro Hayashi
- Department of Materials Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, Yokohama 226-8503, Japan; (S.M.); (S.C.)
| | - Jaegeun Noh
- Department of Chemistry, Hanyang University, Seoul 04763, Republic of Korea; (D.S.); (S.S.); (H.K.); (H.S.O.); (J.H.L.); (H.K.); (Y.O.K.)
- Department of Materials Science and Engineering, School of Materials and Chemical Technology, Tokyo Institute of Technology, Yokohama 226-8503, Japan; (S.M.); (S.C.)
- Research Institute for Convergence of Basic Science, Hanyang University, Seoul 04763, Republic of Korea
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Semwal V, Jensen OR, Bang O, Janting J. Investigation of Performance Parameters of Spherical Gold Nanoparticles in Localized Surface Plasmon Resonance Biosensing. MICROMACHINES 2023; 14:1717. [PMID: 37763880 PMCID: PMC10535430 DOI: 10.3390/mi14091717] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 08/15/2023] [Accepted: 08/29/2023] [Indexed: 09/29/2023]
Abstract
In this paper, we present numerical and experimental results on Localized Surface Plasmon Resonance (LSPR) refractive index (RI) sensitivity, Figure of Merit (FoM), and penetration depth (dp) dependence on spherical gold nanoparticles (AuNPs) size, and the effects of AuNP dimer interparticle distance (ds) studied numerically. These parameters were calculated and observed for d = 20, 40, 60, 80, and 100 nm diameter spherical AuNPs. Our investigation shows d = 60 nm AuNPs give the best FoM. The AuNP dimer interparticle distance can significantly influence the RI sensitivity. Therefore, the effect of distances between pairs of d = 20 nm and 60 nm AuNPs is shown. We discuss the importance of penetration depth information for AuNPs functionalized with aptamers for biosensing in the context of aptamer size.
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Affiliation(s)
- Vivek Semwal
- DTU Electro, Department of Electrical and Photonics Engineering, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
| | | | - Ole Bang
- DTU Electro, Department of Electrical and Photonics Engineering, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
| | - Jakob Janting
- DTU Electro, Department of Electrical and Photonics Engineering, Technical University of Denmark, DK-2800 Kongens Lyngby, Denmark
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Wolf NR, Rai P, Glass M, Milos F, Maybeck V, Offenhäusser A, Wördenweber R. Mechanical and Electronic Cell-Chip Interaction of APTES-Functionalized Neuroelectronic Interfaces. ACS APPLIED BIO MATERIALS 2021; 4:6326-6337. [PMID: 35006867 DOI: 10.1021/acsabm.1c00576] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this work, we analyze the impact of a chip coating with a self-assembled monolayer (SAM) of (3-aminopropyl)triethoxysilane (APTES) on the electronic and mechanical properties of neuroelectronic interfaces. We show that the large signal transfer, which has been observed for these interfaces, is most likely a consequence of the strong mechanical coupling between cells and substrate. On the one hand, we demonstrate that the impedance of the interface between Pt electrodes and an electrolyte is slightly reduced by the APTES SAM. However, this reduction of approximately 13% is definitely not sufficient to explain the large signal transfer of APTES coated electrodes demonstrated previously. On the other hand, the APTES coating leads to a stronger mechanical clamping of the cells, which is visible in microscopic images of the cell development of APTES-coated substrates. This stronger mechanical interaction is most likely caused by the positively charged amino functional group of the APTES SAM. It seems to lead to a smaller cleft between substrate and cells and, thus, to reduced losses of the cell's action potential signal at the electrode. The disadvantage of this tight binding of the cells to the rigid, planar substrate seems to be the short lifetime of the cells. In our case the density of living cells starts to decrease together with the visual deformation of the cells typically at DIV 9. Solutions for this problem might be the use of soft substrates and/or the replacement of the short APTES molecules with larger molecules or molecular multilayers.
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Affiliation(s)
- Nikolaus R Wolf
- Institute of Biological Information Processing - Bioelectronics (IBI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Pratika Rai
- Institute of Biological Information Processing - Bioelectronics (IBI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Manuel Glass
- Institute of Biological Information Processing - Bioelectronics (IBI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Frano Milos
- Institute of Biological Information Processing - Bioelectronics (IBI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Vanessa Maybeck
- Institute of Biological Information Processing - Bioelectronics (IBI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Andreas Offenhäusser
- Institute of Biological Information Processing - Bioelectronics (IBI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Roger Wördenweber
- Institute of Biological Information Processing - Bioelectronics (IBI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
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Jung SH, Seo YM, Gu T, Jang W, Kang SG, Hyeon Y, Hyun SH, Lee JH, Whang D. Super-Nernstian pH Sensor Based on Anomalous Charge Transfer Doping of Defect-Engineered Graphene. NANO LETTERS 2021; 21:34-42. [PMID: 33136414 DOI: 10.1021/acs.nanolett.0c02259] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The conventional pH sensor based on the graphene ion-sensitive field-effect transistor (Gr-ISFET), which operates with an electrostatic gating at the solution-graphene interface, cannot have a pH sensitivity above the Nernst limit (∼59 mV/pH). However, for accurate detection of the pH levels of an aqueous solution, an ultrasensitive pH sensor that can exceed the theoretical limit is required. In this study, a novel Gr-ISFET-based pH sensor is fabricated using proton-permeable defect-engineered graphene. The nanocrystalline graphene (nc-Gr) with numerous grain boundaries allows protons to penetrate the graphene layer and interact with the underlying pH-dependent charge-transfer dopant layer. We analyze the pH sensitivity of nc-Gr ISFETs by adjusting the grain boundary density of graphene and the functional group (OH-, NH2-, CH3-) on the SiO2 surface, confirming an unusual negative shift of the charge-neutral point (CNP) as the pH of the solution increases and a super-Nernstian pH response (approximately -140 mV/pH) under optimized conditions.
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Affiliation(s)
- Su-Ho Jung
- SKKU Advanced Institute of Nanotechnology, Sungkyunkwan University, Suwon 440-746, South Korea
| | - Young-Min Seo
- School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746, South Korea
| | - Taejun Gu
- School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746, South Korea
| | - Wonseok Jang
- School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746, South Korea
| | - Seog-Gyun Kang
- School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746, South Korea
| | - Yuhwan Hyeon
- SKKU Advanced Institute of Nanotechnology, Sungkyunkwan University, Suwon 440-746, South Korea
| | - Sang-Hwa Hyun
- Department of Energy Systems Research and Department of Materials Science and Engineering, Ajou University, Suwon 16499, South Korea
| | - Jae-Hyun Lee
- Department of Energy Systems Research and Department of Materials Science and Engineering, Ajou University, Suwon 16499, South Korea
| | - Dongmok Whang
- SKKU Advanced Institute of Nanotechnology, Sungkyunkwan University, Suwon 440-746, South Korea
- School of Advanced Materials Science and Engineering, Sungkyunkwan University, Suwon 440-746, South Korea
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5
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Cooper O, Phan HP, Wang B, Lowe S, Day CJ, Nguyen NT, Tiralongo J. Functional Microarray Platform with Self-Assembled Monolayers on 3C-Silicon Carbide. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:13181-13192. [PMID: 33104368 DOI: 10.1021/acs.langmuir.0c01306] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Currently available bioplatforms such as microarrays and surface plasmon resonators are unable to combine high-throughput multiplexing with label-free detection. As such, emerging microelectromechanical systems (MEMS) and microplasmonics platforms offer the potential for high-resolution, high-throughput label-free sensing of biological and chemical analytes. Therefore, the search for materials capable of combining multiplexing and label-free quantitation is of great significance. Recently, interest in silicon carbide (SiC) as a suitable material in numerous biomedical applications has increased due to its well-explored chemical inertness, mechanical strength, bio- and hemocompatibility, and the presence of carbon that enables the transfer-free growth of graphene. SiC is also multifunctional as both a wide-band-gap semiconductor and an efficient low-loss plasmonics material and thus is ideal for augmenting current biotransducers in biosensors. Additionally, the cubic variant, 3C-SiC, is an extremely promising material for MEMS, being a suitable platform for the easy micromachining of microcantilevers, and as such capable of realizing the potential of real time miniaturized multiplexed assays. The generation of an appropriately functionalized and versatile organic monolayer suitable for the immobilization of biomolecules is therefore critical to explore label-free, multiplexed quantitation of biological interactions on SiC. Herein, we address the use of various silane self-assembled monolayers (SAMs) for the covalent functionalization of monocrystalline 3C-SiC films as a novel platform for the generation of functionalized microarray surfaces using high-throughput glycan arrays as the model system. We also demonstrate the ability to robotically print high throughput arrays on free-standing SiC microstructures. The implementation of a SiC-based label-free glycan array will provide a proof of principle that could be extended to the immobilization of other biomolecules in a similar SiC-based array format, thus making potentially significant advances to the way biological interactions are studied.
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Wolf NR, Yuan X, Hassani H, Milos F, Mayer D, Breuer U, Offenhäusser A, Wördenweber R. Surface Functionalization of Platinum Electrodes with APTES for Bioelectronic Applications. ACS APPLIED BIO MATERIALS 2020; 3:7113-7121. [PMID: 35019371 DOI: 10.1021/acsabm.0c00936] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The interface between electronic components and biological objects plays a crucial role in the success of bioelectronic devices. Since the electronics typically include different elements such as an insulating substrate in combination with conducting electrodes, an important issue of bioelectronics involves tailoring and optimizing the interface for any envisioned applications. In this paper, we present a method for functionalizing insulating substrates (SiO2) and metallic electrodes (Pt) simultaneously with a stable monolayer of organic molecules ((3-aminopropyl)triethoxysilane (APTES)). This monolayer is characterized by high molecule density, long-term stability, and positive surface net charge and most likely represents a self-assembled monolayer (SAM). It facilitates the conversion of biounfriendly Pt surfaces into biocompatible surfaces, which allows cell growth (neurons) on both functionalized components, SiO2 and Pt, which is comparable to that of reference samples coated with poly-L-lysine (PLL). Moreover, the functionalization greatly improves the electronic cell-chip coupling, thereby enabling the recording of action potential signals of several millivolts at APTES-functionalized Pt electrodes.
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Affiliation(s)
- Nikolaus R Wolf
- Institute of Biological Information Processing, Bioelectronics (IBI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Xiaobo Yuan
- Institute of Biological Information Processing, Bioelectronics (IBI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Hossein Hassani
- Institute of Biological Information Processing, Bioelectronics (IBI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Frano Milos
- Institute of Biological Information Processing, Bioelectronics (IBI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Dirk Mayer
- Institute of Biological Information Processing, Bioelectronics (IBI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Uwe Breuer
- Central Institute for Engineering, Electronics and Analytics-Analytics (ZEA-3), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Andreas Offenhäusser
- Institute of Biological Information Processing, Bioelectronics (IBI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Roger Wördenweber
- Institute of Biological Information Processing, Bioelectronics (IBI-3), Forschungszentrum Jülich, 52425 Jülich, Germany
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7
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Hassani H, Wolf NR, Yuan X, Wördenweber R, Offenhäusser A. Platinum substrate for surface plasmon microscopy at small angles. OPTICS LETTERS 2020; 45:3292-3295. [PMID: 32538965 DOI: 10.1364/ol.396051] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 05/15/2020] [Indexed: 06/11/2023]
Abstract
Platinum is reported as the main component of the substrate in surface plasmon microscopy of the metal-dielectric interface for small-angle measurements. In the absence of a narrow dip in the angular spectrum of platinum, the refractive index of the dielectric medium or the thickness of a deposited layer is proven deducible from the observed sharp peak, close to the critical angle. The sensitivities of refractive index and thickness measurements using platinum are compared with that of a gold surface plasmon resonance chip. Furthermore, the thickness of a structured layer of (3-Aminopropyl)triethoxysilane on the platinum substrate is measured to be 0.7 nm, demonstrating the high sensitivity of the technique.
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8
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Yuan X, Wolf N, Hondrich TJJ, Shokoohimehr P, Milos F, Glass M, Mayer D, Maybeck V, Prömpers M, Offenhäusser A, Wördenweber R. Engineering Biocompatible Interfaces via Combinations of Oxide Films and Organic Self-Assembled Monolayers. ACS APPLIED MATERIALS & INTERFACES 2020; 12:17121-17129. [PMID: 32186363 DOI: 10.1021/acsami.0c02141] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
In this paper, we demonstrate that cell adhesion and neuron maturation can be guided by patterned oxide surfaces functionalized with organic molecular layers. It is shown that the difference in the surface potential of various oxides (SiO2, Ta2O5, TiO2, and Al2O3) can be increased by functionalization with a silane, (3-aminopropyl)-triethoxysilane (APTES), which is deposited from the gas phase on the oxide. Furthermore, it seems that only physisorbed layers (no chemical binding) can be achieved for some oxides (Ta2O5 and TiO2), whereas self-assembled monolayers (SAM) form on other oxides (SiO2 and Al2O3). This does not only alter the surface potential but also affects the neuronal cell growth. The already high cell density on SiO2 is increased further by the chemically bound APTES SAM, whereas the already low cell density on Ta2O5 is even further reduced by the physisorbed APTES layer. As a result, the cell density is ∼8 times greater on SiO2 compared to Ta2O5, both coated with APTES. Furthermore, neurons form the typical networks on SiO2, whereas they tend to cluster to form neurospheres on Ta2O5. Using lithographically patterned Ta2O5 layers on SiO2 substrates functionalized with APTES, the guided growth can be transferred to complex patterns. Cell cultures and molecular layers can easily be removed, and the cell experiment can be repeated after functionalization of the patterned oxide surface with APTES. Thus, the combination of APTES-functionalized patterned oxides might offer a promising way of achieving guided neuronal growth on robust and reusable substrates.
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Affiliation(s)
- Xiaobo Yuan
- Institute of Complex Systems-Bioelectronics (ICS-8), Forschungszentrum Jülich, Jülich 52428, Germany
| | - Nikolaus Wolf
- Institute of Complex Systems-Bioelectronics (ICS-8), Forschungszentrum Jülich, Jülich 52428, Germany
| | - Timm J J Hondrich
- Institute of Complex Systems-Bioelectronics (ICS-8), Forschungszentrum Jülich, Jülich 52428, Germany
| | - Pegah Shokoohimehr
- Institute of Complex Systems-Bioelectronics (ICS-8), Forschungszentrum Jülich, Jülich 52428, Germany
| | - Frano Milos
- Institute of Complex Systems-Bioelectronics (ICS-8), Forschungszentrum Jülich, Jülich 52428, Germany
| | - Manuel Glass
- Institute of Complex Systems-Bioelectronics (ICS-8), Forschungszentrum Jülich, Jülich 52428, Germany
| | - Dirk Mayer
- Institute of Complex Systems-Bioelectronics (ICS-8), Forschungszentrum Jülich, Jülich 52428, Germany
| | - Vanessa Maybeck
- Institute of Complex Systems-Bioelectronics (ICS-8), Forschungszentrum Jülich, Jülich 52428, Germany
| | - Michael Prömpers
- Institute of Complex Systems-Bioelectronics (ICS-8), Forschungszentrum Jülich, Jülich 52428, Germany
| | - Andreas Offenhäusser
- Institute of Complex Systems-Bioelectronics (ICS-8), Forschungszentrum Jülich, Jülich 52428, Germany
| | - Roger Wördenweber
- Institute of Complex Systems-Bioelectronics (ICS-8), Forschungszentrum Jülich, Jülich 52428, Germany
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Minoshima W, Hosokawa C, Kudoh SN, Tawa K. Real-time fluorescence measurement of spontaneous activity in a high-density hippocampal network cultivated on a plasmonic dish. J Chem Phys 2020; 152:014706. [PMID: 31914750 DOI: 10.1063/1.5131497] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
High-density cultured neuronal networks have been used to evaluate synchronized features of neuronal populations. Voltage-sensitive dye (VSD) imaging of a dissociated cultured neuronal network is a critical method for studying synchronized neuronal activity in single cells. However, the signals of VSD are generally too faint-that is, the signal-to-noise ratio (S/N) is too low-to detect neuronal activity. In our previous research, a silver (Ag) plasmonic chip enhanced the fluorescence intensity of VSD to detect spontaneous neural spikes on VSD imaging. However, no high-density network was cultivated on the Ag plasmonic chip, perhaps because of the chemical instability of the Ag surface. In this study, to overcome the instability of the chip, we used a chemically stable gold (Au) plasmonic dish, which was a plastic dish with a plasmonic chip pasted to the bottom, to observe neuronal activity in a high-density neuronal network. We expected that the S/N in real-time VSD imaging of the Au plasmonic chip would be improved compared to that of a conventional glass-bottomed dish, and we also expected to detect frequent neural spikes. The increase in the number of spikes when inhibitory neurotransmitter receptors were inhibited suggests that the spikes corresponded to neural activity. Therefore, real-time VSD imaging of an Au plasmonic dish was effective for measuring spontaneous network activity in a high-density neuronal network at the spatial resolution of a single cell.
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Affiliation(s)
- Wataru Minoshima
- School of Science and Technology, Kwansei Gakuin University, Hyogo, Japan
| | - Chie Hosokawa
- School of Science and Technology, Kwansei Gakuin University, Hyogo, Japan
| | - Suguru N Kudoh
- School of Science and Technology, Kwansei Gakuin University, Hyogo, Japan
| | - Keiko Tawa
- School of Science and Technology, Kwansei Gakuin University, Hyogo, Japan
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Hondrich TJJ, Deußen O, Grannemann C, Brinkmann D, Offenhäusser A. Improvements of Microcontact Printing for Micropatterned Cell Growth by Contrast Enhancement. MICROMACHINES 2019; 10:E659. [PMID: 31574944 PMCID: PMC6848919 DOI: 10.3390/mi10100659] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 09/23/2019] [Accepted: 09/25/2019] [Indexed: 12/26/2022]
Abstract
Patterned neuronal cell cultures are important tools for investigating neuronal signal integration, network function, and cell-substrate interactions. Because of the variable nature of neuronal cells, the widely used coating method of microcontact printing is in constant need of improvements and adaptations depending on the pattern, cell type, and coating solutions available for a certain experimental system. In this work, we report on three approaches to modify microcontact printing on borosilicate glass surfaces, which we evaluate with contact angle measurements and by determining the quality of patterned neuronal growth. Although background toxification with manganese salt does not result in the desired pattern enhancement, a simple heat treatment of the glass substrates leads to improved background hydrophobicity and therefore neuronal patterning. Thirdly, we extended a microcontact printing process based on covalently linking the glass surface and the coating molecule via an epoxysilane. This extension is an additional hydrophobization step with dodecylamine. We demonstrate that shelf life of the silanized glass is at least 22 weeks, leading to consistently reliable neuronal patterning by microcontact printing. Thus, we compared three practical additions to microcontact printing, two of which can easily be implemented into a workflow for the investigation of patterned neuronal networks.
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Affiliation(s)
- Timm J J Hondrich
- Institute of Complex Systems, Bioelectronics (ICS-8), Forschungszentrum Jülich, 52428 Jülich, Germany.
- Faculty of Mathematics, Computer Science and Natural Sciences, RWTH Aachen University, 52076 Aachen, Germany.
| | - Oliver Deußen
- Institute of Complex Systems, Bioelectronics (ICS-8), Forschungszentrum Jülich, 52428 Jülich, Germany.
- Faculty of Mathematics, Computer Science and Natural Sciences, RWTH Aachen University, 52076 Aachen, Germany.
| | - Caroline Grannemann
- Institute of Complex Systems, Bioelectronics (ICS-8), Forschungszentrum Jülich, 52428 Jülich, Germany.
- Faculty of Mathematics, Computer Science and Natural Sciences, RWTH Aachen University, 52076 Aachen, Germany.
| | - Dominik Brinkmann
- Institute of Complex Systems, Bioelectronics (ICS-8), Forschungszentrum Jülich, 52428 Jülich, Germany.
- Faculty of Mathematics, Computer Science and Natural Sciences, RWTH Aachen University, 52076 Aachen, Germany.
| | - Andreas Offenhäusser
- Institute of Complex Systems, Bioelectronics (ICS-8), Forschungszentrum Jülich, 52428 Jülich, Germany.
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11
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Yuan X, Wolf N, Mayer D, Offenha Usser A, Wo Rdenweber R. Vapor-Phase Deposition and Electronic Characterization of 3-Aminopropyltriethoxysilane Self-Assembled Monolayers on Silicon Dioxide. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:8183-8190. [PMID: 31144819 DOI: 10.1021/acs.langmuir.8b03832] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Although organosilanes, especially 3-aminopropyltriethoxysilane (APTES), are commonly used to functionalize oxide substrates for a variety of applications ranging from molecular/biosensors and electronics to protective layers, reliable and controlled deposition of these molecules remains a major obstacle. In this study, we use surface potential analyses to record and optimize the gas-phase deposition of APTES self-assembled monolayers (SAMs) and to determine the resulting change of the electrokinetic potential and charge at the solid?liquid interface when the system is exposed to an electrolyte. Using a gas-phase molecular layer deposition setup with an in situ molecule deposition sensor, APTES is deposited at room temperature onto ozone-activated SiO2. The resulting layers are characterized using various techniques ranging from contact angle analysis, ellipsometry, fluorescence microscopy, X-ray photoelectron spectroscopy, and electrokinetic analysis to AFM. It turns out that adequate postdeposition treatment is crucial to the formation of perfect molecular SAMs. We demonstrate how a thick layer of APTES molecules is initially adsorbed at the surface; however, the molecules do not bind to SiO2 and are removed if the film is exposed to an electrolyte. Only if the film is kept in a gaseous environment (preferable at low pressure) for a long enough time do APTES molecules start to bind to the surface and form the SAM layer. During this time, superfluous molecules are removed. The resulting modification of the electrokinetic potential at the surface is analyzed in detail for different states.
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Affiliation(s)
- Xiaobo Yuan
- Institute of Complex Systems?Bioelectronics (ICS-8) , Forschungszentrum Ju?lich , Ju?lich 52428 , Germany
| | - Nikolaus Wolf
- Institute of Complex Systems?Bioelectronics (ICS-8) , Forschungszentrum Ju?lich , Ju?lich 52428 , Germany
| | - Dirk Mayer
- Institute of Complex Systems?Bioelectronics (ICS-8) , Forschungszentrum Ju?lich , Ju?lich 52428 , Germany
| | - Andreas Offenha Usser
- Institute of Complex Systems?Bioelectronics (ICS-8) , Forschungszentrum Ju?lich , Ju?lich 52428 , Germany
| | - Roger Wo Rdenweber
- Institute of Complex Systems?Bioelectronics (ICS-8) , Forschungszentrum Ju?lich , Ju?lich 52428 , Germany
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Markov A, Maybeck V, Wolf N, Mayer D, Offenhäusser A, Wördenweber R. Engineering of Neuron Growth and Enhancing Cell-Chip Communication via Mixed SAMs. ACS APPLIED MATERIALS & INTERFACES 2018; 10:18507-18514. [PMID: 29763286 DOI: 10.1021/acsami.8b02948] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The interface between cells and inorganic surfaces represents one of the key elements for bioelectronics experiments and applications ranging from cell cultures and bioelectronics devices to medical implants. In the present paper, we describe a way to tailor the biocompatibility of substrates in terms of cell growth and to significantly improve cell-chip communication, and we also demonstrate the reusability of the substrates for cell experiments. All these improvements are achieved by coating the substrates or chips with a self-assembled monolayer (SAM) consisting of a mixture of organic molecules, (3-aminopropyl)-triethoxysilane and (3-glycidyloxypropyl)-trimethoxysilane. By varying the ratio of these molecules, we are able to tune the cell density and live/dead ratios of rat cortical neurons cultured directly on the mixed SAM as well as neurons cultured on protein-coated SAMs. Furthermore, the use of the SAM leads to a significant improvement in cell-chip communications. Action potential signals of up to 9.4 ± 0.6 mV (signal-to-noise ratio up to 47) are obtained for HL-1 cells on microelectrode arrays. Finally, we demonstrate that the SAMs facilitate a reusability of the samples for all cell experiments with little re-processing.
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Affiliation(s)
- Aleksandr Markov
- Institute of Complex Systems (ICS-8) , Forschungszentrum Jülich , Jülich 52425 , Germany
| | - Vanessa Maybeck
- Institute of Complex Systems (ICS-8) , Forschungszentrum Jülich , Jülich 52425 , Germany
| | - Nikolaus Wolf
- Institute of Complex Systems (ICS-8) , Forschungszentrum Jülich , Jülich 52425 , Germany
| | - Dirk Mayer
- Institute of Complex Systems (ICS-8) , Forschungszentrum Jülich , Jülich 52425 , Germany
| | - Andreas Offenhäusser
- Institute of Complex Systems (ICS-8) , Forschungszentrum Jülich , Jülich 52425 , Germany
| | - Roger Wördenweber
- Institute of Complex Systems (ICS-8) , Forschungszentrum Jülich , Jülich 52425 , Germany
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13
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Fetterly CR, Olsen BC, Luber EJ, Buriak JM. Vapor-Phase Nanopatterning of Aminosilanes with Electron Beam Lithography: Understanding and Minimizing Background Functionalization. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:4780-4792. [PMID: 29614858 DOI: 10.1021/acs.langmuir.8b00679] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Electron beam lithography (EBL) is a highly precise, serial method for patterning surfaces. Positive tone EBL resists enable patterned exposure of the underlying surface, which can be subsequently functionalized for the application of interest. In the case of widely used native oxide-capped silicon surfaces, coupling an activated silane with electron beam lithography would enable nanoscale chemical patterning of the exposed regions. Aminoalkoxysilanes are extremely useful due to their reactive amino functionality but have seen little attention for nanopatterning silicon surfaces with an EBL resist due to background contamination. In this work, we investigated three commercial positive tone EBL resists, PMMA (950k and 495k) and ZEP520A (57k), as templates for vapor-phase patterning of two commonly used aminoalkoxysilanes, 3-aminopropyltrimethoxysilane (APTMS) and 3-aminopropyldiisopropylethoxysilane (APDIPES). The PMMA resists were susceptible to significant background reaction within unpatterned areas, a problem that was particularly acute with APTMS. On the other hand, with both APTMS and APDIPES exposure, unpatterned regions of silicon covered by the ZEP520A resist emerged pristine, as shown both with SEM images of the surfaces of the underlying silicon and through the lack of electrostatically driven binding of negatively charged gold nanoparticles. The ZEP520A resist allowed for the highly selective deposition of these alkoxyaminosilanes in the exposed areas, leaving the unpatterned areas clean, a claim also supported by contact angle measurements with four probe liquids and X-ray photoelectron spectroscopy (XPS). We investigated the mechanistic reasons for the stark contrast between the PMMA resists and ZEP520A, and it was found that the efficacy of resist removal appeared to be the critical factor in reducing the background functionalization. Differences in the molecular weight of the PMMA resists and the resulting influence on APTMS diffusion through the resist films are unlikely to have a significant impact. Area-selective nanopatterning of 15 nm gold nanoparticles using the ZEP520A resist was demonstrated, with no observable background conjugation noted in the unexposed areas on the silicon surface by SEM.
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Affiliation(s)
- Christopher R Fetterly
- Department of Chemistry , University of Alberta , 11227 Saskatchewan Drive , Edmonton , Alberta T6G 2G2 , Canada
- National Institute for Nanotechnology, National Research Council Canada , 11421 Saskatchewan Drive , Edmonton , Alberta T6G 2M9 , Canada
| | - Brian C Olsen
- Department of Chemistry , University of Alberta , 11227 Saskatchewan Drive , Edmonton , Alberta T6G 2G2 , Canada
- National Institute for Nanotechnology, National Research Council Canada , 11421 Saskatchewan Drive , Edmonton , Alberta T6G 2M9 , Canada
| | - Erik J Luber
- Department of Chemistry , University of Alberta , 11227 Saskatchewan Drive , Edmonton , Alberta T6G 2G2 , Canada
- National Institute for Nanotechnology, National Research Council Canada , 11421 Saskatchewan Drive , Edmonton , Alberta T6G 2M9 , Canada
| | - Jillian M Buriak
- Department of Chemistry , University of Alberta , 11227 Saskatchewan Drive , Edmonton , Alberta T6G 2G2 , Canada
- National Institute for Nanotechnology, National Research Council Canada , 11421 Saskatchewan Drive , Edmonton , Alberta T6G 2M9 , Canada
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