Surface Plasmon Biosensor Research Articles

Detection of pathogens in water using long range surface plasmon resonance biosensor: Numerical investigation

This work presents a numerical demonstration for improving the imaging sensitivity of long-range surface plasmon (LRSPR) biosensors using the prism 2S2G/cytop/Cu/Gr (Graphene)/sensing medium (SM) configuration. In the suggested LRSPR biosensor, the imaging sensitivity is compared to that of the traditional surface plasmon sensor (tSPR) through numerical analysis. The proposed LRSPR sensor reaches 4655.7/RIU as its maximum imaging sensitivity for detecting E. coli bacteria. The maximum electric field intensity is found at the interface between the Cu/SM in the tSPR sensor and the Gr/SM in the proposed sensor. For pathogens detection such as pure-water (P.W.), Vibrio-Cholera (V.C.), Escherichia-Coli (E.coli), Bacillus-Anthracis (B.A.), and Enterococcus -aecalis (B.F), the penetration depth (PD) for the LRSPR sensor are 304.46 nm, 955.45 nm, 961.45 nm, 957.44 nm and 1050.7 nm. The LRSPR sensor's effectiveness in biosensing applications is further demonstrated by its figure of merit (FoM) for the detection of pathogens bacteria, which is 291.8/RIU (V.C), 781.5/RIU (E.coli), 59.28/RIU(B.A.) and 738.5/RIU (E.F.), respectively.

Surface Plasmon Electrochemistry: Tutorial and Review

Surface plasmon polaritons (SPPs) are optical surface waves propagating along a metal surface. They exhibit attributes such as field enhancement and sub-wavelength localization, which make them attractive for surface sensing, as they are heavily exploited in surface plasmon biosensors. Electrochemistry also occurs on metal surfaces, and electrochemical techniques are also commonly applied in biosensors. As metal surfaces are integral in both, it is natural to combine these techniques into a single platform. Motivations include: (i) realising a multimodal biosensor (electrochemical and optical), (ii) using SPPs to probe the electrochemical double layer or to probe electrochemical activity, thus revealing complementary information on redox reactions, or (iii) using SPPs to pump electrochemical reactions by creating non-equilibrium energetic electrons and holes in a working electrode through the absorption of SPPs thereon. The latter is of interest as it may yield novel redox reaction pathways (i.e., plasmonic electrocatalysis).

Graphene-based biosensors for detecting coronavirus: a brief review.

The coronavirus (SARS-CoV-2) disease has affected the globe with 770 437 327 confirmed cases, including about 6 956 900 deaths, according to the World Health Organization (WHO) as of September 2023. Hence, it is imperative to develop diagnostic technologies, such as a rapid cost-effective SARS-CoV-2 detection method. A typical biosensor enables biomolecule detection with an appropriate transducer by generating a measurable signal from the sample. Graphene can be employed as a component for ultrasensitive and selective biosensors based on its physical, optical, and electrochemical properties. Herein, we briefly review graphene-based electrochemical, field-effect transistor (FET), and surface plasmon biosensors for detecting the SARS-CoV-2 target. In addition, details on the surface modification, immobilization, sensitivity and limit of detection (LOD) of all three sensors with regard to SARS-CoV-2 were reported. Finally, the point-of-care (POC) detection of SARS-CoV-2 using a portable smartphone and a wearable watch is a current topic of interest.

Titanium dioxide, black phosphorus and bimetallic layer-based surface plasmon biosensor for formalin detection: numerical analysis

Titanium dioxide, black phosphorus and bimetallic layer-based surface plasmon biosensor for formalin detection: numerical analysis

Surface plasmon biosensor based on Bi2Te3 antimonene heterostructure for the detection of cancer cells.

This theoretical investigation proposes the preliminary stage detection of cancer cells using a prism-based surface plasmon resonance biosensor. The surface plasmon resonance (SPR) biosensor is label-free and rapid; it supports real-time investigations, including greater sensitivity, and it has an enormous possibility for detecting different forms of cancer. The refractive index alteration of cancer cells is 1.360-1.401. The performance of the SPR sensor has been analyzed. The different types of cancer cells for skin, cervical, blood, adrenal, and breast (type I and II) have been analyzed, and sensitivities of 292, 384, 229, 242, 254, and 261 (degree/RIU) have been achieved, respectively. A high figure of merit of 115.2RIU-1 has been achieved for HeLa cells and achieved detection accuracy of 0.32deg-1 for basal cells.

Zinc sulfide, silicon dioxide, and black phosphorus based ultra-sensitive surface plasmon biosensor

The optical biosensor is the emerging research area in the field of bio-photonics. The black phosphorus zinc sulfide-based hybrid configuration is suitable for implementing and analyzing ultrasensitive biosensors. Ag/Zinc sulfide/silicon dioxide/black phosphorus-based biosensor has been implemented in the proposed work using the modified Kretschmann configuration. The sensitivity improvement of the designed SPR sensor is analyzed in the different arrangements of the layers. The thickness of the layers of all the materials has been optimized. The thickness of the Ag metal layer is optimized and taken as 45 nm. The sensitivity and quality factor measured here is as high as $$664.6^\circ {\text{/RIU}}$$ and 200 at 1.37 refractive index with the P-polarized light source of $$633\;{\text{nm}}$$ wavelength. The proposed biosensor confirms tremendous sensitivity, detection accuracy, and quality factor growth compared with the traditional SPR sensors. Zinc sulfide has multiple applications in the sensing fields, like sensors based on UV rays, lasers, and gas.

D-shaped surface plasmon resonance biosensor based on [formula omitted] in terahertz band

We propose a terahertz surface plasmon biosensor based on MoS2 for detecting blood components. The change of the thickness of MoS2 has a great influence on the amount of resonance peak drift. The ultra-high wavelength sensitivity and resolution ratio of the biosensor are 715.59 μm/RIU and 1.40 × 10−7 RIU, respectively. When the overall structure of the sensor changes by ±0.4%, the maximum relative error of the resonance frequency is 1.3699%, and the maximum relative error of the peak loss is 1.5327%, which are all within a reasonable range and will not affect the sensor’ performance.

Multi-diffractive grating for surface plasmon biosensors with direct back-side excitation.

A multi-diffractive nanostructure is reported for the resonant excitation of surface plasmons that are cross-coupled through a thin metallic film. It consists of two superimposed periodic corrugations that allow diffraction excitation of surface plasmons on the inner side of a thin metal film and their subsequent phase matching with counterpropagating surface plasmons travelling to the opposite direction on its other side. This interaction leads to establishing of a set of cross-coupled Bragg-scattered surface plasmon modes that exhibit an electromagnetic field localized on both metal film interfaces. The reported structure is attractive for surface plasmon resonance biosensor applications, where direct optical probing can be done through the substrate without the need of optical matching to a high refractive index prism. In addition, it can be prepared by mass production - compatible means with UV-nanoimprint lithography and its biosensing performance characteristics are demonstrated by refractometric and biomolecular affinity binding studies.

Sputtered transparent conducting graphene films on iron oxide coated glass

This work reports the optical, electrical and morphological properties of graphene (G) films. Firstly, glass substrates were coated with iron oxide (IO) films using a spraying method. Subsequently, the sputtering technique was employed for the formation of graphene films on the IO layers (G/IO films). According to XPS spectra, the IO films offered anchorage sites for the growth of G that improved the adherence to the substrate. Additionally, the sheet resistance of the films was in the range of 16–19.5 kΩ/□. Also, the optical measurements revealed that the G/IO films subjected to a post-deposition heat treatment presented a transmittance ~ 11% higher than those as-deposited. In fact, those heat-treated films presented a transparency above 80% for wavelengths above 850 nm and a high elasticity modulus of 0.188 ± 0.039 TPa, which make them good candidates to be used as transparent conductive electrodes in thin film transistors, surface plasmon biosensors or surface enhanced Raman scattering (SERS) substrates.

Design considerations of highly efficient D-shaped plasmonic biosensor

Design considerations of photonic crystal fiber (PCF) surface plasmon biosensor with high sensitivity to monitor glucose concentration is reported and studied. Based on a well-known large mode area (LMA) single mode PCF, two different configurations have been studied to investigate the impact of the etching process on the biosensor sensitivity. Furthermore, the possibility of infiltrating one hole by a plasmonic material to increases the biosensor sensitivity is studied. A full vectorial finite element method (FVFEM) is used to carry out the analysis of the reported biosensor. In addition, the geometrical parameters of the suggested biosensors have been optimized to obtain the highest sensitivity. The suggested biosensor based on a D-shaped PCF with plasmonic rod achieves sensitivity as high as 13,600 nm/RIU with corresponding resolution of $$ 7.35 \times 10^{ - 6} \;{\text{RIU}} $$ .The analysis also reveals that the proposed biosensor has a linear performance which is needed practically. Therefore, the reported biosensor has advantages in terms of fabrication feasibility and high linear sensitivity.

Light-chain residue 95 is critical for antigen binding and multispecificity of monoclonal antibody G2

The monoclonal antibody, G2, specifically binds to the immunogen peptide derived from the chicken prion protein, Pep18mer, and two chicken proteins derived peptides, Pep8 and Pep395; G2 binds with equal affinity to Pep18mer. The amino acid sequences of the three peptides are completely different, and so the recognition mechanism of G2 is unique and interesting. We generated a single-chain Fv (scFv) antibody of G2, and demonstrated its correct folding with an antigen binding function similar to intact G2 antibody. We also generated a Pro containing mutant of G2 scFv at residue 95 of the light chain, and analyzed its antigen binding using a surface plasmon biosensor. The mutant lost its binding ability to Pep18mer, but remained those to Pep8 and Pep395. The results clearly indicate residue 95 as being critical for multispecific antigen binding of G2 at the site generated from the junctional diversity introduced at the joints between the V and J gene segments.

UV-Written Long-Period Grating Based on Long-Range Surface Plasmon-Polariton Waveguide

This letter proposes a long-period grating based on coupling between the long-range surface plasmon mode and a cladding mode of a thin Au film stripe fully buried in polymer SU-8. Periodical surface corrugation and accompanied refractive index variation on the SU-8 upper-cladding were induced by ultraviolet-written technique. This configuration along the Au stripe gives rise to the observation of strong resonance in a 3-mm long periodic grating. A rejection band with a contrast of −23.5 dB at the wavelength 1561 nm was achieved, which can be tuned by $\sim 30$ nm with a temperature change of 6 °C. The grating offers potential applications in surface plasmon waveguide circuits and biosensors.

Integration of Faradaic electrochemical impedance spectroscopy into a scalable surface plasmon biosensor for in tandem detection.

We present an integrated label-free biosensor based on surface plasmon resonance (SPR) and Faradaic electrochemical impedance spectroscopy (f-EIS) sensing modalities, for the simultaneous detection of biological analytes. Analyte detection is based on the angular spectroscopy of surface plasmon resonance and the extraction of charge transfer resistance values from reduction-oxidation reactions at the gold surface, as responses to functionalized surface binding events. To collocate the measurement areas and fully integrate the modalities, holographically exposed thin-film gold SPR-transducer gratings are patterned into coplanar electrodes for tandem impedance sensing. Mutual non-interference between plasmonic and electrochemical measurement processes is shown, and using our scalable and compact detection system, we experimentally demonstrate biotinylated surface capture of neutravidin concentrations as low as 10 nM detection, with a 5.5 nM limit of detection.

A Surface Plasmon Biosensor Based on a D-Shaped Microstructured Optical Fiber With Rectangular Lattice

A numerical investigation of a surface plasmon biosensor based on D-shaped microstructured optical fiber (MOF) with rectangular lattice is presented. A full-vector finite-element method is applied to analyze the resonance coupling properties. By adjusting the diameters of two large air holes, the proposed biosensor shows excellent performance. High sensitivity and narrow full-width at half-maximum (FWHM) can be achieved. In particular, the figure of merit can reach to 478.3RIU-1, which is to our knowledge the highest among the reported MOF sensors. In the last part, the influence of coating thickness on the sensing performance has been considered.

Surface plasmon resonance-based infrared biosensor for cell studies with simultaneous control.

We report a label-free infrared surface plasmon biosensor with a double-chamber flow cell for continuous monitoring of morphological changes in cell culture exposed to various stimuli. In this technique, the monolayer of cultured cells is divided into two halves by a barrier, allowing the treatment of one half while the other serves as control. We demonstrate the advantages of this setup in test experiments that track kinetics of the IEC-18 cell layer response to variations in extracellular Ca2+ concentration. The sensitivity of the presented method was found to be an order of magnitude higher compared to the single-chamber biosensor.

Design and optimisation of integrated hybrid surface plasmon biosensor

In this paper we present a novel idea for an integrated surface plasmon biosensor. The proposed hybrid sensor aims to couple the high sensitivity of the well known Kretchmann prism excitation design with the more robust integrated waveguide design. The sensor is modelled and simulated using a 2D Finite Element Method (FEM) in order to establish the devices sensitivity, resolution and signal-to-noise-ratio.

TGF-β2 promotes RPE cell invasion into a collagen gel by mediating urokinase-type plasminogen activator (uPA) expression

Transforming growth factor-beta (TGF-β) is one of the main epithelial–mesenchymal transition (EMT)-inducing factors. In general, TGF-β-induced EMT promotes cell migration and invasion. TGF-β also acts as a potent regulator of pericellular proteolysis by regulating the expression and secretion of plasminogen activators. Urokinase-type plasminogen activator (uPA) is a serine protease that binds to its cell surface receptor (uPAR) with high affinity. uPA binding to uPAR stimulates uPAR's interaction with transmembrane proteins, such as integrins, to regulate cytoskeletal reorganization and cell migration, differentiation and proliferation. However, the influence of TGF-β and the uPA/uPAR system on EMT in retinal pigment epithelial (RPE) cells is still unclear. The purpose of this study was to determine the effect of TGF-β2, which is the predominant isoform in the retina, and the uPA/uPAR system on RPE cells. In this study, we first examined the effect of TGF-β2 and/or the inhibitor of uPA (u-PA-STOP®) on the proliferation of a human retinal pigment epithelial cell line (ARPE-19 cells). Treatment with TGF-β2 or u-PA-STOP® suppressed cell proliferation. Combination treatment of TGF-β2 and u-PA-STOP® enhanced cell growth suppression. Furthermore, western blot analysis, fibrin zymography and real-time reverse transcription PCR showed that that TGF-β2 induced EMT in ARPE-19 cells and that the expression of uPA and uPAR expression was up-regulated during EMT. The TGF-β inhibitor SB431542 suppressed TGF-β2-stimulated uPA expression and secretion but did not suppress uPAR expression. Furthermore, we seeded ARPE-19 cells onto Transwell chambers and allowed them to invade the collagen matrix in the presence of TGF-β2 alone or with TGF-β2 and u-PA-STOP®. TGF-β2 treatment induced ARPE-19 cell invasion into the collagen gel. Treatment with a combination of TGF-β2 and the uPA inhibitor strongly inhibited ARPE-19 cell invasion compared with treatment with TGF-β2 alone. Furthermore, the interaction between uPA and ARPE-19 cells was analyzed using a surface plasmon biosensor system. The binding of uPA to ARPE-19 cells was observed. In addition, TGF-β2 significantly promoted the binding activity of uPA to ARPE-19 cells in a time-dependent or cell-number-dependent fashion. These results indicate that TGF-β-induced EMT-associated phenotype changes in ARPE-19 cells and the invasiveness of ARPE-19 cells into a collagen gel matrix are mediated, at least in part, by uPA.

Resolution Estimation of the Au, Ag, Cu, and Al Single- and Double-Layer Surface Plasmon Sensors in the Ultraviolet, Visible, and Infrared Regions

Figures of merit are introduced for estimation of achievable resolution of surface plasmon (SP) sensors by modulation type. The resolution of SP sensors in the Kretschmann’s geometry is estimated by numerical simulation for combinations of silver (Ag), copper (Cu), aluminum (Al), chromium, and titanium layers with a gold (Au) layer in the ultraviolet (UV), visible, and infrared (IR) regions in cases of detecting the change of the refractive index of water and the presence of an adsorption layer in water. SP biosensors with angular modulation based on Al exhibit low resolution in the UV region; Ag, Au, and Cu biosensors show best resolution in the visible region. Biosensors with intensity modulation demonstrate high performance in the near IR by Ag, Au, and Cu metals, and in the UV by Al.

Biosensing using surface electromagnetic waves in photonic band gap multilayers

Abstract A biosensor based on the excitation of surface electromagnetic waves in photonic band gap multilayer films is demonstrated. The operating principle of this device is similar to surface plasmon biosensors with the key difference that a photonic band gap film replaces the metal film as the medium in which surface electromagnetic waves are excited. The use of photonic band gap films offers a number of advantages. First, the surface wave resonance is much sharper leading to the potential of greatly enhanced sensitivity. Second, the properties of the photonic band gap material can be engineered to make a sensor that operates at any wavelength. The experiments reported here are conducted with a surface wave resonance at 470 nm, a wavelength not generally accessible with surface plasmon sensing. Finally, the photonic band gap films are more mechanically robust than metal films and they offer new substrates for surface chemistry. The paper describes the design of the photonic band gap films, the surface chemistry and biology to create sensing chips, and the spectroscopic experimental configuration used to observe and track the surface mode resonance. Experimental results are presented on refractive index sensing, antibody–antigen reactions, and DNA binding.

Exploration of the binding proteins of perfluorooctane sulfonate by a T7 phage display screen

Perfluorooctane sulfonate (PFOS) is a pollutant widely found throughout nature and is toxic to animals. We created a PFOS analogue on a polyethylene glycol polyacrylamide copolymer and isolated peptides that preferentially bound the PFOS analogue using a T7 phage display system. Bioinformatic analysis using the FASTAskan program on the RELIC bioinformatics server showed several human proteins that likely bound PFOS. Among them, we confirmed binding between PFOS and a recombinant soluble form of monocyte differentiation antigen CD14 (sCD14) by a surface plasmon biosensor. Furthermore, PFOS inhibited TNF-α production induced by the sCD14 in mouse macrophage RAW264.7 cells.