Individual Plasmonic Nanostructures as Label Free Biosensors

Biosensing requires fast, selective, and highly sensitive real-time detection of biomolecules using efficient simple-to-use techniques. Due to a unique capability to focus light at nanoscale, plasmonic nanostructures provide an excellent platform for label-free detection of molecular adsorption by sensing tiny changes in the local refractive index or by enhancing the light-induced processes in adjacent biomolecules. This review discusses the opportunities provided by surface plasmon resonance in probing the chirality of biomolecules as well as their conformations and orientations. Various types of chiral plasmonic nanostructures and the most recent developments in the field of chiral plasmonics related to biosensing are considered.

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Label free chemical sensors based on plasmonic nanostructures: modeling and functional characterization

18th Italian National Conference on Photonic Technologies (Fotonica 2016) ◽

10.1049/cp.2016.0899 ◽

2016 ◽

Author(s):

A. Colombelli ◽

M.G. Manera ◽

A. Taurino ◽

R. Rella

Keyword(s):

Chemical Sensors ◽

Functional Characterization ◽

Plasmonic Nanostructures ◽

Label Free

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Extracellular Vesicle Identification Using Label-Free Surface-Enhanced Raman Spectroscopy: Detection and Signal Analysis Strategies

Molecules ◽

10.3390/molecules25215209 ◽

2020 ◽

Vol 25 (21) ◽

pp. 5209

Author(s):

Hyunku Shin ◽

Dongkwon Seo ◽

Yeonho Choi

Keyword(s):

Raman Spectroscopy ◽

Free Surface ◽

Signal Analysis ◽

Surface Enhanced Raman Spectroscopy ◽

Pattern Identification ◽

Plasmonic Nanostructures ◽

Label Free ◽

Surface Enhanced ◽

Analysis Strategies ◽

Surface Enhanced Raman

Extracellular vesicles (EVs) have been widely investigated as promising biomarkers for the liquid biopsy of diseases, owing to their countless roles in biological systems. Furthermore, with the notable progress of exosome research, the use of label-free surface-enhanced Raman spectroscopy (SERS) to identify and distinguish disease-related EVs has emerged. Even in the absence of specific markers for disease-related EVs, label-free SERS enables the identification of unique patterns of disease-related EVs through their molecular fingerprints. In this review, we describe label-free SERS approaches for disease-related EV pattern identification in terms of substrate design and signal analysis strategies. We first describe the general characteristics of EVs and their SERS signals. We then present recent works on applied plasmonic nanostructures to sensitively detect EVs and notable methods to interpret complex spectral data. This review also discusses current challenges and future prospects of label-free SERS-based disease-related EV pattern identification.

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Rayleigh anomaly-enabled mode hybridization in gold nanohole arrays by scalable colloidal lithography for highly-sensitive biosensing

Nanophotonics ◽

10.1515/nanoph-2021-0563 ◽

2022 ◽

Vol 0 (0) ◽

Author(s):

Zhiliang Zhang ◽

Feng Zhao ◽

Renxian Gao ◽

Chih-Yu Jao ◽

Churong Ma ◽

...

Keyword(s):

Refractive Index ◽

Plasmonic Nanostructures ◽

Label Free ◽

Colloidal Lithography ◽

Large Area ◽

Nanohole Array ◽

Highly Sensitive ◽

Label Free Detection ◽

Nanohole Arrays ◽

Rayleigh Anomaly

Abstract Plasmonic sensors exhibit tremendous potential to accomplish real-time, label-free, and high-sensitivity biosensing. Gold nanohole array (GNA) is one of the classic plasmonic nanostructures that can be readily fabricated and integrated into microfluidic platforms for a variety of applications. Even though GNA has been widely studied, new phenomena and applications are still emerging continuously expanding its capabilities. In this article, we demonstrated narrow-band high-order resonances enabled by Rayleigh anomaly in the nanohole arrays that are fabricated by scalable colloidal lithography. We fabricated large-area GNAs with different hole diameters, and investigated their transmission characteristics both numerically and experimentally. We showed that mode hybridization between the plasmon mode of the nanoholes and Rayleigh anomaly of the array could give rise to high-quality decapole resonance with a unique nearfield profile. We experimentally achieved a refractive index sensitivity, i.e., RIS up to 407 nm/RIU. More importantly, we introduced a spectrometer-free refractive index sensing based on lens-free smartphone imaging of GNAs with (intensity) sensitivity up to 137%/RIU. Using this platform, we realized the label-free detection of BSA molecules with concentration as low as 10−8 M. We believe our work could pave the way for highly sensitive and compact point-of-care devices with cost-effective and high-throughput plasmonic chips.

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Label-free, mass-sensitive single-molecule imaging using interferometric scattering microscopy

Essays in Biochemistry ◽

10.1042/ebc20200023 ◽

2020 ◽

Author(s):

Nikolas Hundt

Keyword(s):

Single Molecule ◽

Cellular Systems ◽

Single Molecule Imaging ◽

Label Free ◽

Measurement Sensitivity ◽

Mass Distributions ◽

Quantitative Measurements ◽

Contrast Mechanism ◽

Cellular Components ◽

Scattering Signal

Abstract Single-molecule imaging has mostly been restricted to the use of fluorescence labelling as a contrast mechanism due to its superior ability to visualise molecules of interest on top of an overwhelming background of other molecules. Recently, interferometric scattering (iSCAT) microscopy has demonstrated the detection and imaging of single biomolecules based on light scattering without the need for fluorescent labels. Significant improvements in measurement sensitivity combined with a dependence of scattering signal on object size have led to the development of mass photometry, a technique that measures the mass of individual molecules and thereby determines mass distributions of biomolecule samples in solution. The experimental simplicity of mass photometry makes it a powerful tool to analyse biomolecular equilibria quantitatively with low sample consumption within minutes. When used for label-free imaging of reconstituted or cellular systems, the strict size-dependence of the iSCAT signal enables quantitative measurements of processes at size scales reaching from single-molecule observations during complex assembly up to mesoscopic dynamics of cellular components and extracellular protrusions. In this review, I would like to introduce the principles of this emerging imaging technology and discuss examples that show how mass-sensitive iSCAT can be used as a strong complement to other routine techniques in biochemistry.

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A microfluidic device with integrated impedance detection for λ-DNA

MRS Proceedings ◽

10.1557/proc-773-n6.5 ◽

2003 ◽

Vol 773 ◽

Cited By ~ 1

Author(s):

Myung-Il Park ◽

Jonging Hong ◽

Dae Sung Yoon ◽

Chong-Ook Park ◽

Geunbae Im

Keyword(s):

Microfluidic Device ◽

Electrochemical Impedance ◽

Direct Detection ◽

Full Potential ◽

Label Free ◽

Buffer Solution ◽

Detection Systems ◽

Significant Difference ◽

Detection Of Biomolecules ◽

Impedance Magnitude

AbstractThe large optical detection systems that are typically utilized at present may not be able to reach their full potential as portable analysis tools. Accurate, early, and fast diagnosis for many diseases requires the direct detection of biomolecules such as DNA, proteins, and cells. In this research, a glass microchip with integrated microelectrodes has been fabricated, and the performance of electrochemical impedance detection was investigated for the biomolecules. We have used label-free λ-DNA as a sample biomolecule. By changing the distance between microelectrodes, the significant difference between DW and the TE buffer solution is obtained from the impedance-frequency measurements. In addition, the comparison for the impedance magnitude of DW, the TE buffer, and λ-DNA at the same distance was analyzed.

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