scholarly journals Theoretical Study on the Detection of Tilted Lipid Bilayers Using Surface Plasmon Resonance Techniques

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Koyo Watanabe ◽  
Koji Matsuura

Effective refractive indices detected using surface plasmon resonance techniques are calculated as a function of the tilt angle of lipid bilayers in a multilayered model. The changes in the effective refractive indices are derived from the shift of an excitation angle of surface plasmon. To obtain effective refractive index plots, we determined refractive index changes in the lipid bilayers with 3 and 5 nm thicknesses as a function of tilt angle and obtained a relationship between the effective refractive index and tilt angle. We also showed that the effective refractive index depended on the lipid bilayers thickness and anisotropic permittivities, which vary with interchain distance.

2010 ◽  
Vol 26 (2) ◽  
pp. 674-681 ◽  
Author(s):  
Yuhki Yanase ◽  
Takaaki Hiragun ◽  
Sakae Kaneko ◽  
Hannah J. Gould ◽  
Malcolm W. Greaves ◽  
...  

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Hyeong-Min Kim ◽  
Jae-Hyoung Park ◽  
Seung-Ki Lee

Abstract Fiber-optic-based localized surface plasmon resonance (FO-LSPR) sensors with three-dimensional (3D) nanostructures have been developed. These sensors were fabricated using zinc oxide (ZnO) nanowires and gold nanoparticles (AuNPs) for highly sensitive plasmonic biosensing. The main achievements in the development of the biosensors include: (1) an extended sensing area, (2) light trapping effect by nanowires, and (3) a simple optical system based on an optical fiber. The 3D nanostructure was fabricated by growing the ZnO nanowires on the cross-section of optical fibers using hydrothermal synthesis and via immobilization of AuNPs on the nanowires. The proposed sensor outputted a linear response according to refractive index changes. The 3D FO-LSPR sensor exhibited an enhanced localized surface plasmon resonance response of 171% for bulk refractive index changes when compared to the two-dimensional (2D) FO-LSPR sensors where the AuNPs are fixed on optical fiber as a monolayer. In addition, the prostate-specific antigen known as a useful biomarker to diagnose prostate cancer was measured with various concentrations in 2D and 3D FO-LSPR sensors, and the limits of detection (LODs) were 2.06 and 0.51 pg/ml, respectively. When compared to the 2D nanostructure, the LOD of the sensor with 3D nanostructure was increased by 404%.


2012 ◽  
Vol 112 (3) ◽  
pp. 034505 ◽  
Author(s):  
Kerstin Kämpf ◽  
Sebastian Kübler ◽  
Friedrich Wilhelm Herberg ◽  
Arno Ehresmann

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.


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