Development of highly sensitive optical nanoantenna for bacterial detection

Itagaki, Satohiro; Tanabe, So; Ikeda, Hikaru; Shan, Xueling; Nishii, Shigeki; Yamamoto, Yojiro; Sadanaga, Yasuhiro; Chen, Zhidong; Shiigi, Hiroshi

doi:10.1039/d2an00475e

Cited by 3 publications

(4 citation statements)

References 26 publications

(38 reference statements)

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“…Bacterial cultures and all experiments were developed and managed in a Biosafety Level 2 laboratory in accordance with the appropriate safety regulations (WHO Laboratory Biosafety Manual). 6,7 The bacterial strain was cultured in an agar growth medium (E-MC35, Eiken Chemical, Japan) at 310 K for 18 h. A single colony was selected, placed in a liquid growth medium (5.0 mL), and incubated at 310 K for 6 h. The precipitate was dispersed in sterile ultrapure water and the E. coli K12 suspension concentration was adjusted to 3.6 © 10 11 CFU mL ¹1 .…”

Section: Methodsmentioning

confidence: 99%

“…4,5 In recent years, many studies have reported on the development of biosensors using novel materials and technologies. For highly sensitive and rapid detection of pathogenic bacteria, biosensors based on physical or chemical signals, such as light scattering, [6][7][8][9] fluorescence, 10,11 electrochemistry, [12][13][14][15] and piezoelectricity, 16 have been developed. In particular, electrochemical biosensors are particularly useful in fields where on-site testing is required because of their high sensitivity, rapid measurement, and ease of device miniaturization.…”

Section: Introductionmentioning

confidence: 99%

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Electrochemical Evaluation of the Number of Viable Bacteria Using Carbon Electrode Chip

IKEDA,

TOKONAMI,

NAKAO

et al. 2024

Electrochemistry

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To perform on-site bacterial testing at food and pharmaceutical manufacturing sites, it is desired to develop a new method that can quickly measure the number of viable bacterial cells. We have succeeded in measuring the number of viable bacteria using small and inexpensive disposable electrode chips focusing on electrochemical methods that realize quick detection and device miniaturization. The oxidized form of the tetrazolium salt, 3-(4,5dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), is soluble and highly permeable through cell membranes. MTT is a useful indicator for evaluating cell activity that not only turns color as a result of structural changes related to intracellular metabolism but also causes a clear current response. The carbon-screen-printed electrode chip provides a distinct current response related to the MTT redox reaction in a small volume of bacterial suspension (50 µL). Based on the fact that the current reaction of MTT was strongly dependent on intracellular metabolism, the number of viable cells in a bacterial suspension could be measured electrochemically. Current changes for live cells occurred within 10 min and increased with the incubation time. After only 60 min of incubation, we successfully estimated the number of viable cells in a bacterial suspension of 10 3 CFU mL −1 . This technology eliminates the need for complicated testing, expensive equipment, and lengthy culture testing times, thereby enabling the confirmation of food safety before shipping to prevent food poisoning.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Electrochemical Evaluation of the Number of Viable Bacteria Using Carbon Electrode Chip

IKEDA,

TOKONAMI,

NAKAO

et al. 2024

Electrochemistry

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“…Localized surface plasmon resonance (LSPR) phenomenon will occur when the frequency of the incident light is consistent with the natural frequency oscillation of the electrons on the metallic nanoantenna surface, resulting in the enormous electric field [3][4][5]. Nanoantenna structures supporting LSPR offer a way to break the optical diffraction limit by concentrating light into subwavelengths [6][7][8][9]. The distribution of the electric field depends on the configuration of plasmonic nanoantenna, which typically exhibits strong enhancement and localization on the surface of the antenna, especially at the smaller tips and gaps of dimers or polymers [10][11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Surface-enhanced photoluminescence and Raman spectroscopy of single molecule confined in coupled Au bowtie nanoantenna

Pei,

Peng,

Zhang

et al. 2024

Nanotechnology

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Optical nanoantennas possess broad applications in the fields of photodetection, environmental science, biosensing and nonlinear optics, owing to their remarkable ability to enhance and confine the optical field at the nanoscale. In this article, we present a theoretical investigation of surface-enhanced photoluminescence spectroscopy for single molecules confined within novel Au bowtie nanoantenna, covering a wavelength range from the visible to near-infrared spectral regions. We employ the finite element method to quantitatively study the optical enhancement properties of the plasmonic field, quantum yield, Raman scattering and fluorescence. Additionally, we systematically examine the contribution of nonlocal dielectric response in the gap mode to the quantum yield, aiming to gain a better understanding of the fluorescence enhancement mechanism. Our results demonstrate that altering the configuration of the nanoantenna has a significant impact on plasmonic sensitivity. The nonlocal dielectric response plays a crucial role in reducing the quantum yield and corresponding fluorescence intensity when the gap distance is less than 3 nm. However, a substantial excitation field can effectively overcome fluorescence quenching and enhance the fluorescence intensity. By optimizing nanoantenna configuration, the maximum enhancement of surface-enhanced Raman can be turned to 9 and 10 magnitude orders in the visible and near-infrared regions, and 3 and 4 magnitude orders for fluorescence enhancement, respectively. The maximum spatial resolutions of 0.8 nm and 1.5 nm for Raman and fluorescence are also achieved, respectively. Our calculated results not only provide theoretical guidance for the design and application of new nanoantennas, but also contribute to expanding the range of surface-enhanced Raman and fluorescence technology from the visible to the near-infrared region.

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“…Compared to bulk metals, metal nanoparticles possess unique properties such as catalytic activity and localized surface plasmons due to specific surface area effects. − In addition, using glass or a polymer to protect the metal nanoparticles facilitates their stable dispersion and optimizes their exceptional characteristics. − Conductive polymers such as polyaniline (PANI), polypyrrole, and PEDOT can be easily synthesized using chemical and electrochemical methods and can be easily hybridized with metal nanoparticles. − The hybridization of metal nanoparticles and conductive polymers is expected to endow various functions, such as environmental stability, electrical conductivity, and electrochemical activity. , Previously, we successfully developed organic–inorganic hybrids with a densely assembled structure of gold nanoparticles (AuNPs) in a PANI matrix. − This fabrication method exploited the fact that the reduction of aurate by aniline and the oxidation of aniline by aurate occurred in the same reaction field, enabling the production of nanometer-scale hybrids in a single process. We attempted to detect bacteria using the characteristic optical and electrochemical properties of the hybrids. − …”

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confidence: 99%

Simultaneous Electrochemical Detection of Multiple Bacterial Species Using Metal–Organic Nanohybrids

Itagaki,

Nakao,

Nakamura

et al. 2024

Anal. Chem.

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Organic metallic nanohybrids (NHs), in which many small metal nanoparticles are encapsulated within a conductive polymer matrix, are useful as sensitive electrochemical labels because the constituents produce characteristic oxidation current responses. Gold NHs, consisting of gold nanoparticles and poly(m-toluidine), and copper NHs, consisting of copper nanoparticles and polyaniline, did not interfere with each other in terms of the electrochemical signals obtained on the same electrode. Antibodies were introduced into these NHs to function as electrochemical labels for targeting specific bacteria. Electrochemical measurements using screen-printed electrodes dry-fixed with NH-labeled bacterial cells enabled the estimation of bacterial species and number within minutes, based on the distinct current response of the labels. Our proposed method achieved simultaneous detection of enterohemorrhagic Escherichia coli and Staphylococcus aureus in a real sample. These NHs will be powerful tools as electrochemical labels and are expected to be useful for rapid testing in food and drug-related manufacturing sites.

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Development of highly sensitive optical nanoantenna for bacterial detection

Abstract: Gold nanoparticles (AuNPs) are chemically stable and serve as excellent labels because their characteristic red coloration based on the localized surface plasmon resonance does not fade. However, it is necessary...

Cited by 3 publications

References 26 publications

Electrochemical Evaluation of the Number of Viable Bacteria Using Carbon Electrode Chip

Electrochemical Evaluation of the Number of Viable Bacteria Using Carbon Electrode Chip

Surface-enhanced photoluminescence and Raman spectroscopy of single molecule confined in coupled Au bowtie nanoantenna

Simultaneous Electrochemical Detection of Multiple Bacterial Species Using Metal–Organic Nanohybrids

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