Review Cite This: Chem. Rev. XXXX, XXX, XXX−XXX
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Plasmonic Biosensing Focus Review J. R. Mejía-Salazar*,†,‡ and Osvaldo N. Oliveira, Jr.*,‡ †
National Institute of Telecommunications (Inatel), 37540-000, Santa Rita do Sapucaí, MG, Brazil São Carlos Institute of Physics, University of São Paulo, CP 369, 13560-970, São Carlos, SP, Brazil
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ABSTRACT: Plasmonic biosensing has been used for fast, real-time, and label-free probing of biologically relevant analytes, where the main challenges are to detect small molecules at ultralow concentrations and produce compact devices for point-of-care (PoC) analysis. This review discusses the most recent, or even emerging, trends in plasmonic biosensing, with novel platforms which exploit unique physicochemical properties and versatility of new materials. In addition to the well-established use of localized surface plasmon resonance (LSPR), three major areas have been identified in these new trends: chiral plasmonics, magnetoplasmonics, and quantum plasmonics. In describing the recent advances, emphasis is placed on the design and manufacture of portable devices working with low loss in different frequency ranges, from the infrared to the visible.
CONTENTS 1. Introduction 2. LSPR Biosensing 3. Chiral Plasmonic Biosensing 4. Magnetoplasmonic Biosensing 5. Quantum Plasmonics Biosensing 6. Outlook Author Information Corresponding Authors ORCID Notes Biographies Acknowledgments References
(mainly induced through adsorption processes). In spite of the extensive research efforts on SPR biosensing since its first demonstration around four decades ago,4−6 detection of small analytes or dispersed in solutions at very low concentrations remains challenging. The difficulty lies in the negligible changes in dielectric properties in close proximity to the metal/dielectric interface, which may be circumvented through improved sensing performances. For example, SPR spectroscopy can be combined with other techniques to increase the signal for a proper detection scheme. However, high-field intensities are not suitable for biological measurements because they may photodamage the sample under study or induce other undesirable effects, such as thermal modulation of the SPR signal. Many strategies have therefore been proposed in the literature to address these limitations. Here we review the most recent advances, especially in the last two years, in plasmonic biosensing and their prospects for device applications. We identified four major areas into which these advances may be classified. The first is well established and related to the various schemes to employ localized SPRs (LSPRs). The other three areas are not consolidated yet. They involve the use of chiral properties in plasmonic systems, which are especially relevant for biomolecules; magneto-optical effects with tailored film architectures; and quantum concepts to overcome the shot-noise limit in sensing and biosensing. We take one of the main goals in plasmonic biosensing, namely to produce integrated, PoC devices, as reference to discuss progress, and the challenges and opportunities in the four areas.
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1. INTRODUCTION The resonant coupling of electromagnetic waves to collective oscillations of free electrons in metals, known as surface plasmon resonances (SPRs), has been exploited largely because of the possible control of light properties at the nanometer scale.1,2 The possibility to enhance and confine light at dimensions much smaller than the incident wavelength has opened up new routes for integrated nanophotonics and miniaturized optoelectronic devices. Such enhancement and confinement of light occurs at the interface between two media with dielectric constants of opposite signs, typically a dielectric and a metal, and there is a rapid decay as it is drawn away from the interface. These properties make plasmonic platforms suitable for low-cost point-of-care (PoC) diagnostic devices,3 owing to their integration into microfluidic systems and high sensitivity to changes of dielectric properties at the interface © XXXX American Chemical Society
Received: June 4, 2018
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DOI: 10.1021/acs.chemrev.8b00359 Chem. Rev. XXXX, XXX, XXX−XXX
Chemical Reviews
Review
Figure 1. (A) Cryo-TEM tomography reconstruction image of the double-helical structure of Au-NRs. The inset shows a zoomed view of the region marked on the left-side. (B) Near-field distribution for a dipolar LSPR in a metallic NR. (C) Pictorial representation of the system in (A) for the purpose of numerical simulations. (D) Simplification of the system in (C), considering only two Au-NRs. (E) and (F) are the extinction and CD spectra, respectively, for the double-helical Au-NRs arrangement after addition of 30 μL of purified brain homogenates from healthy (blacklines) and PD-affected (red-lines) patients. (G) Schematic CD spectrum for circularly polarized incident radiation of a plasmonic enantiomer. The inset shows a pictorial view of circularly polarized light interacting with a left-handed plasmonic nanohelix. (H), (I), and (J) depict the corresponding resonance shifts, when RI of the surrounding medium changes from n1 to n2 (n1
