Plasmonic Refractive Index Sensor Enhanced with Chitosan/Au Bilayer Thin Film for Dopamine Detection

Abstract

Surface plasmonic sensors have received considerable attention, found extensive applications, and outperformed conventional optical sensors. In this work, biopolymer chitosan (CS) was used to prepare the bilayer structure (CS/Au) of a plasmonic refractive index sensor for dopamine (DA) detection. The sensing characteristics of the developed plasmonic sensor were evaluated. Increasing DA concentrations significantly shifted the SPR dips. The sensor exhibited stability and a refractive index sensitivity of 8.850°/RIU in the linear range 0.1 nM to 1 µM with a detection limit of 0.007 nM and affinity constant of 1.383 × 108 M−1. The refractive index and thickness of the CS/Au structure were measured simultaneously by fitting the obtained experimental findings to theoretical data based on Fresnel equations. The fitting yielded the refractive index values n (1.5350 ± 0.0001) and k (0.0150 ± 0.0001) for the CS layer contacting 0.1 nM of DA, and the thickness, d was (15.00 ± 0.01) nm. Then, both n and d values increased by increasing DA concentrations. In addition, the changes in the FTIR spectrum and the variations in sensor surface roughness and structure obtained by AFM analysis confirmed DA adsorption on the sensing layer. Based on these observations, CS/Au bilayer has enhanced the performance of this plasmonic sensor, which showed promising importance as a simple, low-cost, and reliable platform for DA sensing.

Fiber Optic SPR Sensor Modified With Copper Oxide Nanoparticles for Highly Sensitive and Selective Detection of Dopamine

“…For colorimetric method, analysis of colorless compounds is not possible and does not work in IR and UV regions [44] [45]. On the other hand, SPR sensors based on glass chips [29], [51] show better detection limits than these techniques. The proposed work utilizes optical fiber as a substrate which offers several advantages such as electromagnetic interference immunity and remote detection, which are not possible for glass chip-based sensors.…”

“…Recently, another SPR sensor was reported with a bilayer structure of chitosan and gold-film to sense dopamine [29].…”

Silver Nanoparticles’ Localized Surface Plasmon Resonances Emerged in Polymeric Environments: Theory and Experiment

“…One notable approach involves combining plasmonic nanoparticles with polymers, resulting in the development of plasmonic-polymer nanocomposites and hybrid plasmonic nanostructures [17][18][19][20]. The goal of this combination is to obtain novel materials and devices with enhanced functionality and responsiveness [21][22][23]. The synergistic effects of these hybrid nanostructured materials can be leveraged in functional systems, endowing them with remarkable optoelectronic, sensing, catalytic, and antibacterial properties, as well as improved light harvesting efficiency [17,18,[24][25][26][27][28].…”

Multi-functional photonic spin Hall effect sensor controlled by phase transition

“…[1][2][3] Nowadays, due to the advantages of fast response and precise real-time detection, a variety of optical RI sensors have been developed, which are widely used to monitor the tiny change of the chemical constituents (e.g., 10 −9 RIU, which corresponds to approximately 1 fmol/L of salt in water). [4][5][6] For example, Jian et al demonstrated the highly sensitive cell concentration detection by exploiting the resonant optical tunneling effect (ROTE), with a desirable sensitivity of 19 µm/RIU. [7] It is reported that the nano-dot enhanced plasmonic biosensor can detect the fractional changes of the electrolyte concentration and glucose concentration in human blood.…”