scholarly journals Numerical Study on the Surface Plasmon Resonance Tunability of Spherical and Non-Spherical Core-Shell Dimer Nanostructures

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1728
Author(s):  
Joshua Fernandes ◽  
Sangmo Kang

The near-field enhancement and localized surface plasmon resonance (LSPR) on the core-shell noble metal nanostructure surfaces are widely studied for various biomedical applications. However, the study of the optical properties of new plasmonic non-spherical nanostructures is less explored. This numerical study quantifies the optical properties of spherical and non-spherical (prolate and oblate) dimer nanostructures by introducing finite element modelling in COMSOL Multiphysics. The surface plasmon resonance peaks of gold nanostructures should be understood and controlled for use in biological applications such as photothermal therapy and drug delivery. In this study, we find that non-spherical prolate and oblate gold dimers give excellent tunability in a wide range of biological windows. The electromagnetic field enhancement and surface plasmon resonance peak can be tuned by varying the aspect ratio of non-spherical nanostructures, the refractive index of the surrounding medium, shell thickness, and the distance of separation between nanostructures. The absorption spectra exhibit considerably greater dependency on the aspect ratio and refractive index than the shell thickness and separation distance. These results may be essential for applying the spherical and non-spherical nanostructures to various absorption-based applications.

Photonics ◽  
2021 ◽  
Vol 8 (2) ◽  
pp. 41
Author(s):  
Najat Andam ◽  
Siham Refki ◽  
Hidekazu Ishitobi ◽  
Yasushi Inouye ◽  
Zouheir Sekkat

The determination of optical constants (i.e., real and imaginary parts of the complex refractive index (nc) and thickness (d)) of ultrathin films is often required in photonics. It may be done by using, for example, surface plasmon resonance (SPR) spectroscopy combined with either profilometry or atomic force microscopy (AFM). SPR yields the optical thickness (i.e., the product of nc and d) of the film, while profilometry and AFM yield its thickness, thereby allowing for the separate determination of nc and d. In this paper, we use SPR and profilometry to determine the complex refractive index of very thin (i.e., 58 nm) films of dye-doped polymers at different dye/polymer concentrations (a feature which constitutes the originality of this work), and we compare the SPR results with those obtained by using spectroscopic ellipsometry measurements performed on the same samples. To determine the optical properties of our film samples by ellipsometry, we used, for the theoretical fits to experimental data, Bruggeman’s effective medium model for the dye/polymer, assumed as a composite material, and the Lorentz model for dye absorption. We found an excellent agreement between the results obtained by SPR and ellipsometry, confirming that SPR is appropriate for measuring the optical properties of very thin coatings at a single light frequency, given that it is simpler in operation and data analysis than spectroscopic ellipsometry.


2021 ◽  
Author(s):  
Weijian Gao ◽  
Caixia Kan ◽  
Shanlin Ke ◽  
Qinru Yun ◽  
Xingzhong Zhu ◽  
...  

Noble metal nanocrystals and the core-shell nanocomposites have attracted particular interest due to their unique optical properties originated from the surface plasmon resonance (SPR) and wide applications related to the...


Author(s):  
Wida Yanti ◽  
Kamsul Abraha ◽  
Agung Bambang

A theoretical analysis of haemoglobin (Hb) concentration detection is presented in this work with the objective of achieving more sensitive detection and monitoring low concentrations. Surface-enhanced SPR spectroscopy on silver nanoparticles was employed for recording Hb concentrations less than 10 g/L. In this paper, Fe3O4@Au core-shell, nanocomposite spherical nanoparticle consisting of a spherical Fe3O4 core covered by Au shell, was used as an active material for biomolecules detection in the Surface Plasmon Resonance (SPR)-based biosensor in the wavelength 632.8 nm. We present the simulation of detection amplification technique through Attenuated Total Reflection (ATR) spectrum in the Kretschmann configuration. The system consists of a four-layer material i.e., prism/Ag/Fe3O4@Au+Hb/air. Dielectric function determination of the core-shell nanoparticle (Fe3O4@Au) and the composite (Fe3O4@Au+Hb) was done by applying the Effective Medium Theory approximation and the calculation of the reflectivity is carried out by varying the size of core-shell (r0). In this simulation, the refractive index of the BK7 prism is 1.51; the refractive index of Ag thin film is 0.13455 + 3.98651i with the thickness of 40 nm, and the refractive index of the composite is varied depending on the size of nanoparticle core-shell. Our results show that by varying the radius of the core and the shell thickness, the dip of the reflectivity (ATR) spectrum is shifted to the larger angle of incident light and the addition of core-shell in the conventional SPR-based biosensor leads to enhancement of the SPR biosensor sensitivity, for the core-shell radius 10 nm, the sensitivity increased by 1.35% for F = 0.1, and by 4.89% for F = 0.8 compared to the sensitivity of the conventional SPR-based biosensor without core-shell addition.


2021 ◽  
Author(s):  
Jian-Fei Liao ◽  
Dao-Ming Lu ◽  
Li-Jun Chen ◽  
Tian-Ye Huang

Abstract A new design of surface plasmon resonance (SPR) sensor employing circular-lattice holey fiber to achieve high-sensitivity detection is proposed. The sensing performance of the proposed sensor is numerically investigated and the study results indicate that our proposed SPR sensor can be applied to the near-mid infrared detection. Moreover, the maximum wavelength sensitivity of our proposed sensor can reach as high as 1.76×104 nm/refractive index unit (RIU) and the maximum wavelength interrogation resolution can be up to 5.68×10-6 RIU when the refractive index (RI) of analyte lies in (1.31, 1.36). Thanks to its excellent sensing performance, our proposed SPR sensor will have great potential applications for biological analytes detection, food safety control, bio-molecules detection and so on.


2017 ◽  
Vol 9 (1) ◽  
pp. 23 ◽  
Author(s):  
Arthur Gontier ◽  
J. Marae-Djouda ◽  
R. Caputo ◽  
Y. Madi ◽  
M. Molinari ◽  
...  

In this contribution, a numerical study of the optical properties of closely-packed gold nanorods was performed. The studied nano-objects are experimentally grown on a tilted polydimethylsiloxane (PDMS) substrate by using physical vapor deposition (PVD). This method creates nanorods tilted to a certain angle with respect to the substrate normal. This geometry allows exciting both transverse and longitudinal modes of the rods. As demonstrated in a previous experimental work, such PVD-grown nano-objects show promising possibilities both as strain gauges or strain-tunable metamaterials if fabricated on a stretchable dielectric substrate. This numerical study is based on experimental data from previous work and pushes further the subject by approaching an optimized nano-structure allowing better strain-sensitivity (particularly by changing the auto-organization of the said nanorods). Full Text: PDF ReferencesJ.W.M. Chon, C. Bullen, P. Zijlstra, M. Gu, "Spectral encoding on Gold Nanorods Doped in a Silica Sol?Gel Matrix and Its Application to High-Density Optical Data Storage", Adv. Funct. Mater. 17, 875 (2007). CrossRef C.-C. Chen, Y.-P. Lin, C.-W. Wang, H.-C. Tzeng, C.-H. Wu, Y.-C. Chen, C.-P. Chen, L.-C. Chen, Y.-C. Wu, "DNA?Gold Nanorod Conjugates for Remote Control of Localized Gene Expression by near Infrared Irradiation", J. Am. Chem. Soc. 128, 3709 (2006). CrossRef J.N. Anker, W.P. Hall, O. Lyandres, N.C. Shah, J. Zhao, R.P. Van Duyne, "Biosensing with plasmonic nanosensors", Nat. Mater 7, 442 (2008). CrossRef B. Sepulveda, P.C. Angelome, L.M. Lechuga, L.M. Liz-Marzan?, "LSPR-based nanobiosensors", Nano Today 4, 244 (2009). CrossRef A. Haes, R.P. Van Duyne, "A Nanoscale Optical Biosensor: Sensitivity and Selectivity of an Approach Based on the Localized Surface Plasmon Resonance Spectroscopy of Triangular Silver Nanoparticles", J. Am. Chem. Soc. 124, 10596 (2002). CrossRef J.C. Riboh, A.J. Haes, A.D. McFarland, C.R. Yonzon, R.P. Van Duyne, "A Nanoscale Optical Biosensor: Real-Time Immunoassay in Physiological Buffer Enabled by Improved Nanoparticle Adhesion", J. Phys. Chem. B 107, 1772 (2003). CrossRef C.R. Yonzon, E. Jeoung, S. Zou, G.C. Schatz, M. Mrksich, R.P. Van Duyne, "A Comparative Analysis of Localized and Propagating Surface Plasmon Resonance Sensors: The Binding of Concanavalin A to a Monosaccharide Functionalized Self-Assembled Monolayer", J. Am. Chem. Soc. 126, 12669 (2004). CrossRef A.J. Haes, L. Chang, W.L. Klein, R.P. Van Duyne, "Detection of a Biomarker for Alzheimer's Disease from Synthetic and Clinical Samples Using a Nanoscale Optical Biosensor", J. Am. Chem. Soc. 127, 2264 (2005). CrossRef R. Caputo, G. Palermo, M.Infusino L. De Sio, "Liquid Crystals as an Active Medium: Novel Possibilities in Plasmonics", Nanospectroscopy 1, 40 (2015). CrossRef T. Maurer, J. Marae-Djouda, U. Cataldi, A. Gontier, G. Montay, Y. Madi, B. Panicaud, D. Macias, P.-M. Adam, G. Lév?que, T. Bürgi, R. Caputo, "The beginnings of plasmomechanics: towards plasmonic strain sensors", Frontiers of Materials Science 9, 170 (2015). CrossRef X. Niu, S. P. Stagon, H. Huang, J.K. Baldwin, A. Misra, "Smallest Metallic Nanorods Using Physical Vapor Deposition", Phys. Rev. Lett. 110 136102 (2013). CrossRef Lumerical Solutions, Inc. DirectLink P.K. Jain, W. Huang, M.A.El-Sayed, "On the Universal Scaling Behavior of the Distance Decay of Plasmon Coupling in Metal Nanoparticle Pairs: A Plasmon Ruler Equation", Nanoletters 7, 2080 (2007). CrossRef P.K. Jain, M.A. El-Sayed, "Plasmonic coupling in noble metal nanostructures", Chem. Phys. Letters 487, 153 (2010). CrossRef


Author(s):  
Wida Yanti ◽  
Kamsul Abraha ◽  
Agung Bambang S.U.

A theoretical analysis of haemoglobin (Hb) concentration detection is presented in this work with the objective of achieving more sensitive detection and monitoring low concentrations. Surface-enhanced SPR spectroscopy on silver nanoparticles was employed for recording Hb concentrations less than 10 g/L. In this paper, Fe3O4@Au core-shell, nanocomposite spherical nanoparticle consisting of a spherical Fe3O4 core covered by Au shell, was used as an active material for biomolecules detection in the Surface Plasmon Resonance (SPR)-based biosensor in the wavelength 632.8 nm. We present the simulation of detection amplification technique through Attenuated Total Reflection (ATR) spectrum in the Kretschmann configuration. The system consists of a four-layer material i.e prism/Ag/Fe3O4@Au+Hb/air. Dielectric function determination of the core-shell nanoparticle (Fe3O4@Au) and the composite (Fe3O4@Au+Hb) was done by applying the Effective Medium Theory approximation and the calculation of the reflectivity is carried out by varying the size of core-shell (r0). In this simulation, the refractive index of the BK7 prism is 1.51; the refractive index of Ag thin film is 0.13455+3.98651i with the thickness of 40 nm, and the refractive index of the composite is varied depending on the size of nanoparticle core-shell. Our results show that by varying the radius of the core and the shell thickness, the dip of the reflectivity (ATR) spectrum is shifted to the larger angle of incident light and the addition of core-shell in the conventional SPR-based biosensor leads to enhancement of the SPR biosensor sensitivity, for the core-shell radius 10 nm, the sensitivity increased by 1.35% for F = 0.1, and by 4.89% for F =0.8 compared to the sensitivity of the conventional SPR-based biosensor without core-shell addition.


2021 ◽  
Vol 4 (2) ◽  
pp. 995-999
Author(s):  
Zheng Fu ◽  
Zhengxi Xuan ◽  
Changning Li ◽  
Liang Qiao ◽  
Yang Liu ◽  
...  

Sensors ◽  
2021 ◽  
Vol 21 (13) ◽  
pp. 4348
Author(s):  
Piotr Mrozek ◽  
Ewa Gorodkiewicz ◽  
Paweł Falkowski ◽  
Bogusław Hościło

Comparative analysis of the sensitivity of two surface plasmon resonance (SPR) biosensors was conducted on a single-metallic Au sensor and bimetallic Ag–Au sensor, using a cathepsin S sensor as an example. Numerically modeled resonance curves of Au and Ag–Au layers, with parameters verified by the results of experimental reflectance measurement of real-life systems, were used for the analysis of these sensors. Mutual relationships were determined between ∂Y/∂n components of sensitivity of the Y signal in the SPR measurement to change the refractive index n of the near-surface sensing layer and ∂n/∂c sensitivity of refractive index n to change the analyte’s concentration, c, for both types of sensors. Obtained results were related to experimentally determined calibration curves of both sensors. A characteristic feature arising from the comparison of calibration curves is the similar level of Au and Ag–Au biosensors’ sensitivity in the linear range, where the signal of the AgAu sensor is at a level several times greater. It was shown that the influence of sensing surface morphology on the ∂n/∂c sensitivity component had to be incorporated to explain the features of calibration curves of sensors. The shape of the sensory surface relief was proposed to increase the sensor sensitivity at low analyte concentrations.


2021 ◽  
Vol 140 ◽  
pp. 106551
Author(s):  
Sumaiya Akhtar Mitu ◽  
Kawsar Ahmed ◽  
Fahad Ahmed Al Zahrani ◽  
Amit Grover ◽  
Murugan Senthil Mani Rajan ◽  
...  

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