Detection of Nicotine Effect on Colon Cells in a Plasmonic Platform

Introduction: Smoking as one of the causes of various diseases has encouraged worldwide studies on its adverse pharmacological effects on different organs. Nicotine may influence the smooth muscles of the colon and subsequently the gut motility, which leads to a change in the moving rate of digested material through the gastrointestinal tract.Methods: Among various techniques, optical detection methods benefit from non-contact and high-sensitivity for studying the early effect of nicotine on the cells. Thus, we used an optically ellipsometric method to get the fast and sensitive nicotine effect on the colon cell. Two-dimensional plasmonic platforms by gold deposition onto the polydimethylsiloxane polymer (PDMS) patterned substrate were used as the guest medium of the cell and the sample was excited by all of the visible region wavelengths at different exposure time and maintenance time.Results: Our results showed that the phase difference between each polarization increased by augmenting the exposure time of smoke over the cell at a fixed maintenance time and there was a general red-shift by increasing the maintenance time at a fixed exposure time.Conclusion: Using different exposure time to cigarette smoke, we optically showed that the cigarette containing the addicting chemical of nicotine had a direct effect on the cultured colon cells on our 2D biocompatible plasmonic chip. It demonstrated considerable changes in the amplitude and phase of the interacted light by injecting nicotine into the system with the aid of the label-free and non-invasive plasmonic technique

Role of higher order plasmonic modes in one-dimensional nanogratings

By theoretically investigating the optical behavior of one-dimensional gold nanogratings using Fourier Modal Method, we have shown that both integer and non-integer multiples of surface plasmon polariton wavelengths should be taken into consideration in special optical contrast ratio for highly sensitive sensing. The emergence of higher modes is the key factor for the formation of observed plasmonic band gap. Through considering the significant role of grating period and thickness respectively in horizontal and vertical surface resonances, it was demonstrated that for gold thicknesses below 100nm, the dominant phenomenon is horizontal surface resonances while for increased thicknesses both horizontal and vertical surface resonances mediate. The transmission minima are insensitive to the grating thickness, which confirms that their origins are not vertical surface resonances. This study can open an avenue towards designing highly sensitive sensors with focus not only on the plasmonic resonance wavelength but also on its integer and non-integer multiples whose origins should be investigated in both horizontal and vertical surface resonances

Design and modeling of photonic crystal Absorber by using Gold and graphene films

A novel absorber based on a one-dimensional photoniccrystal (PhC) is proposed by combining the absorptionproperty of gold and graphene films. We designed twophotonic crystals consisting of silicon and silicondioxide layers with lattice constants 125 and 260 thatalternate in one dimension. We placed a 125-nanometerthicklayer of graphene between the two photoniccrystals and an 8-nanometer-thick layer of gold at theend of the second photonic crystal. When graphene isplaced between two photonic crystals, a topological edgemode excitation creates a strong absorptionenhancement. In this study, the absorbing spectrums andfield distribution are analyzed by using the transfermatrix and the 2.5 dimensional variational finitedifference time domain method (2.5 var.FDTD). Theabsorption spectrum for different angles was studied(θ=0 to 60), and more than 87 percent absorption can bemaintained for θ =40°. The results of our studies willenhance the interaction between light and matter. Thus,opening up the possibility of their application for theabsorption and modulation of ligh

Gain enhancement of circular waveguide antennas using near-zero index metamaterials

In this article, a rigorous analytical methodology is introduced for designing near-zero refractive index metamaterials (NZIMs). Our proposed NZIM media is realized by three stacked layers of perforated metallic surfaces, each layer composed of a fishnet-like periodic array of square holes. By a proper design of such structures, a low refractive index medium is achieved at their corresponding plasma frequency. The low refractive index property is studied by retrieving the effective parameters of NZIM via inversion techniques, which gives an effective near-zero refractive index, at an operating frequency of 1.5 GHz. Then, the designed NZIM is used for gain enhancement of a circular waveguide antenna. The analysis shows that the proposed platform can enhance the directivity of our antenna by 3 dB while maintaining the return loss <-20 dB

Blue-shift ultrasensitivity using rhombus-shaped plasmonic crystal on Si3N4 membrane

Harnessing ultrasensitivity from optical structures to detect tiny changes in the targeted samples is the main goal of scientists in the field of sensor design. In this study, an uncommon rhombus-shape plasmonic structure is proposed for providing blue-shift ultrasensitivity. The physical origin of this optical response relies on multi-faces of gold rhombus and their electromagnetic coupling with their induced images in a high-refractive-index substrate (Si3N4). A characteristic of blue-shift emerges as the Fano resonance in the reflection spectrum. We have experimentally shown that this novel structure has the surface sensitivity to the refractive index difference in the order of 10(-5). These characteristics have been applied for non- and conditioned- cell culture medium with refractive differences in this order.This level of sensitivity is interesting for enhanced fingerprinting of minute quantities of targeted molecules and interfacial ion redistribution. (c) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreemen

Effect of Methadone and Tramadol Opioids on Stem Cells Based on Integrated Plasmonic-Ellipsometry Technique: Effect of Opioids on Stem Cells Based on plasmonics

Introduction: Plasmonic biosensors provide high sensitivity in detecting the low amount of biomarkers and pharmaceutical drugs. We studied the mesenchyme cell activity under the treatment of common sedative drugs of methadone and tramadol using the integrated plasmonic-ellipsometry technique.Methods: Mesenchymal stem cells were cultured on patterned plasmonic chips under the treatment of methadone and tramadol drugs. Three cultured chips were kept non-treated as the control ones. The plasmonic-ellipsometry technique was applied to study the signaling characteristic of the cells affected by these two drugs. In this technique, optical information regarding the amplitude ratio and phase change between p- and s-polarized light was recorded.Results: This drug treatment could affect the spectral plasmonic resonance and subsequently the phase shift (Δ) and the amplitude ratio (Ψ) values under p- and s-polarized impinging light. A more significant Δ value for tramadol treatment meant that the phase split was larger between p- and s-polarized light. Tramadol also had more prominent absolute Δeff and Ψeff values in comparison with methadone.Conclusion: We showed that tramadol caused more contrast in phase shift (Δ) and amplitude ratio (Ψ) between p- and s-polarized impinging light for cultured stem cells in comparison with methadone. It means that tramadol differentiated more the optical responses for p- and s-polarized lights compared to methadone. Our proposed technique possesses the potential of quantitative and qualitative analysis of drugs on humans even on a cell scale. DOI:10.34172/jlms.2021.4