Surface Plasmon Resonance Spectra Research Articles

A Method for Estimating the Filling Rate of the Mold Cavity in Nanoimprint Lithography.

When the dimensions of a microelectronic structure decrease, high manufacturing costs are inevitable. A low cost and high throughput manufacturing technique for nanostructures is desired. Nanoimprint lithography involves patterning the resist through physical deformation by using a mold at nanoscale and has the potential to meet these expectations. Therefore, nanoimprint lithography has been extensively studied in recent years. Many real time measurements have been proposed for enhancing the yield of nanoimprint lithography. Among these measurements, the application of surface plasmon resonance has the advantage of quick, highly accurate analysis. In surface plasmon resonance application, the mold contains a gold film for exciting surface plasmon resonance and an adhesion layer is applied to both sides of the gold film to increase the lifespan of the mold. However, the effect of the geometric characteristics of the adhesive layer on the surface plasmon resonance spectrum and the mechanical strength of the mold has not been extensively studied. To improve the detection accuracy and reliability of the measurement, this study investigated the aforementioned effect. Analytical and experimental investigations confirmed that the shape of the spectrum is influenced by the surface roughness and thickness of the titanium adhesion layer. To maintain the sharpness of the resonance dip, we suggest reducing the thickness of the titanium adhesion layer to below 6 nm and maintaining the surface roughness below 3 nm. Moreover, the proposed mold structure conforms to these requirements and is applied to estimate the filling rate. The measurement results demonstrate that the surface plasmon resonance spectrum is clearly affected by the mold filling. Specifically, the change in the surface plasmon resonance spectrum curve and resonance angle can indicate the quality of the imprinted pattern. This study demonstrates the effectiveness and high sensitivity of the proposed technique for estimating the filling rate of the mold cavity in nanoimprint lithography.

Detection of Dye Molecules Adsorbed in a Mesoporous Layer by Surface Plasmon Resonance Spectroscopy and its Comparison with Simulation Results

We report in this paper, the utilization of Surface Plasmon Resonance (SPR) spectroscopy to distinct the adsorption type of dye molecules into an Aluminium-doped Zinc Oxide (AZO) mesoporous layer. This was performed in a Kretschmann configuration by measuring the SPR spectra at various incident angles. The SPR spectral dips were then compared with the simulation results calculated on the basis of the transfer-matrix method. There is an agreement between the simulation results and experimental results, which confirm two different kinds of dye adsorption. The first type is pure dye adsorption into the mesoporous layer, while the second type is dye adsorption accompanied by dye deposition on the mesoporous surface.

Two Highly Stable Silver Nanoparticles: Surface Plasmon Resonance Spectra Study of Silver Nanoparticles Capped with m-Hydroxybenzoic Acid and p-Hydroxybenzoic Acid

Silver nanoparticles capped with m-hydroxybenzoic acid and p-hydroxybenzoic have been successfully synthesized, but the long-term stability data of these silver nanoparticles are not available. In this paper, we report the stability of these two types of silver nanoparticles for a period of 40 weeks observation based on the change of surface plasmon resonance spectra of silver nanoparticles. Silver nanoparticles were synthesized by reduction of silver nitrate with m-hydroxybenzoic acid and p-hydroxybenzoic acid without addition of capping agent. The presence of silver nanoparticles was indicated by the appearance of yellow color due to the surface plasmon resonance of silver nanoparticles. The resulted silver nanoparticles were stored at room temperature and further UV-visible spectrophotometer was used to follow the change in surface plasmon resonance spectra. The surface plasmon resonance spectra of silver nanoparticles were overlapped for the first 18 weeks, followed by little change in the position of absorption maxima (lmax), peak intensity, and width of the absorption peak until the week of 40. Silver nanoparticles capped with m-hydroxybenzoic acid and silver nanoparticles capped with p-hydroxybenzoic acid were highly stable which should make them suitable for further applications. The results show the potential of m-hydroxybenzoic acid and p-hydroxybenzoic acid to become a new reducing agent in the synthesis of highly stable silver nanoparticles. The m-hydroxybenzoic acid and p-hydroxybenzoic acid appeared to act as both reducing and capping agent.

A Centimeter-Scale Inorganic Nanoparticle Superlattice Monolayer with Non-Close-Packing and its High Performance in Memory Devices.

Due to the near-field coupling effect, non-close-packed nanoparticle (NP) assemblies with tunable interparticle distance (d) attract great attention and show huge potential applications in various functional devices, e.g., organic nano-floating-gate memory (NFGM) devices. Unfortunately, the fabrication of device-scale non-close-packed 2D NPs material still remains a challenge, limiting its practical applications. Here, a facile yet robust "rapid liquid-liquid interface assembly" strategy is reported to generate a non-close-packed AuNP superlattice monolayer (SM) on a centimeter scale for high-performance pentacene-based NFGM. The d and hence the surface plasmon resonance spectra of SM can be tailored by adjusting the molecular weight of tethered polymers. Precise control over the d value allows the successful fabrication of photosensitive NFGM devices with highly tunable performances from short-term memory to nonvolatile data storage. The best performing nonvolatile memory device shows remarkable 8-level (3-bit) storage and a memory ratio over 105 even after 10 years compared with traditional devices with a AuNP amorphous monolayer. This work provides a new opportunity to obtain large area 2D NPs materials with non-close-packed structure, which is significantly meaningful to microelectronic, photovoltaics devices, and biochemical sensors.

How to accurately predict solution-phase gold nanostar stability.

Unwanted nanoparticle aggregation and/or agglomeration may occur when anisotropic nanoparticles are dispersed in various solvents and matrices. While extended Derjaguin-Landau-Verwey-Overbeek (DLVO) theory has been successfully applied to predict nanoparticle stability in solution, this model fails to accurately predict the physical stability of anisotropic nanostructures; thus limiting its applicability in practice. Herein, DLVO theory was used to accurately predict gold nanostar stability in solution by investigating how the choice of the nanostar dimension considered in calculations influences the calculated attractive and repulsive interactions between nanostructures. The use of the average radius of curvature of the nanostar tips instead of the average radius as the nanostar dimension of interest increases the accuracy with which experimentally observed nanoparticle behavior can be modeled theoretically. This prediction was validated by measuring time-dependent localized surface plasmon resonance (LSPR) spectra of gold nanostars suspended in solutions with different ionic strengths. Minimum energy barriers calculated from collision theory as a function of nanoparticle concentration were utilized to make kinetic predictions. All in all, these studies suggest that choosing the appropriate gold nanostar dimension is crucial to fully understanding and accurately predicting the stability of anisotropic nanostructures such as gold nanostars; i.e., whether the nanostructures remain stable and can be used reproducibly, or whether they aggregate and exhibit inconsistent results. Thus, the present work provides a deeper understanding of internanoparticle interactions in solution and is expected to lead to more consistent and efficient analytical and bioanalytical applications of these important materials in the future. Graphical abstract ᅟ.

Capping of supramolecular curcubit[7]uril facilitates formation of Au nanorods during pre-reduction by curcumin

Curcumin being biologically available and non-toxic natural compound is an attractive and alternative green reagent for the reduction of gold salts to elemental gold. Here, we bring new insight that shape and size of the Au nanoparticles (NPs) can be tuned by using curcumin in combination with supramolecular host molecule such as curcubit[7]uril (CB[7]) as stabilizing agent. It is found that AuNPs prepared using curcumin alone in aqueous environment gives spherical and smaller size, 10–20 nm, particles with its surface Plasmon resonance peak at ∼536 nm. At the same time when CB[7] is used as a capping agent along with curcumin, larger size NPs and at higher concentration (∼50 μM) of CB[7] Au nanorods (NRs) are formed with a broad surface Plasmon resonance spectrum peaked at ∼610 nm. Thus, CB[7] at higher concentration ultimately helps to form Au NRs. Formation of AuNPs and AuNRs has been confirmed by XRD and conjugation of CB[7] and curcumin is established by FT-IR and TGA data. However, these particles aggregate in solution to form particles between 200 nm and 300 nm with a polydispersity of 0.25 as observed in DLS. Zeta potential measurement indicates formation of stable nanoparticles/nanorods without further precipitation within time. Kinetic study shows that the half-life for the formation of AuNP/NRs is ∼36 min, whereas degradation of curcumin during synthesis has a half-life of ∼10 min, this discrepancy suggests some amount of curcumin degrades on its own during this process besides acting as reducing agent.

Fluorescence chemodosimeter for dopamine based on the inner filter effect of the in situ generation of silver nanoparticles and fluorescent dye

A new strategy for the sensitive and selective detection of dopamine (DA) was proposed. The chemodosimeter design was based on the measurement of the fluorescent quenching of fluorescein dye caused by the in situ generation of silver nanoparticles (AgNPs). The AgNPs can be simply generated by a reaction between DA and Ag+ in the presence of polymethacrylic acid (PMAA). In addition, the generated AgNPs possess the maximum surface plasmon resonance (SPR) at 440 nm and an increase in the SPR intensity with an increasing DA concentration. Basically, fluorescein dye can emit the fluorescent intensity maximum at 513 nm with excitation at 487 nm. Thus, fluorescent quenching was achieved due to an inner filter effect from the overlap between the excitation spectrum of the fluorescein dye and the SPR spectrum of the generated AgNPs. The degree of fluorescent quenching linearly depends on the number of generated AgNPs that can be directly related to the concentration of DA. The proposed chemodosimeter can be used to detect DA in a working linear concentration range of 1.0–5.0 μM at a detection limit of 10.6 nM. This chemodosimeter was successfully applied to determine DA in a real urine sample and a dopamine injection formulation with satisfactory results.

A sensitive and selective colorimetric sensor for reduced glutathione detection based on silver triangular nanoplates conjugated with gallic acid

Silver triangular nanoplates conjugated with gallic acid (AgTNPs⋅GA) was designed and synthesized for colorimetric detection of reduced glutathione (GSH). The surface plasmon resonance (SPR) properties of AgTNPs⋅GA were strongly influenced by the addition of GSH. The detection principle was based on the aggregation of AgTNPs⋅GA, which leads to the significant bathochromic shift of the SPR spectra from 602 nm to 650 nm. The dramatic color changes from the initial dark blue to light blue can be observed, which allowed simple monitoring of GSH ether by naked eye and UV–vis spectrophotometer. With UV–vis spectrophotometer measurements, a quantitative linearity was established in the range of 0.5–5.0 nM (R2 = 0.9919) and with a limit of detection (LOD) of 0.12 ± 0.02 nM. Relative standard deviation (RSD) of 3.46% and 1.82% (n = 10) were achieved for the determination of 1.0 and 3.0 nM, respectively. No interfering substances such as ascorbic acid, glucose, sucrose, citric acid, cysteine, Ca2+, Mg2+, Fe3+ and K+ were revealed in the AgTNPs⋅GA based assay. The proposed colorimetric strategy could be extended as the general platform for detection of GSH in dietary supplements and no significant differences in accuracy and precision were observed compared to HPLC standard method.

The Effective Killing Percentages of Hela Cells By Gold Nanoparticles and IR Irradiation

Cancer photothermal therapy (PTT) depends on the size, and shape of nanoparticles, consequently, on the surface plasmon resonance (SPR) peaks of the gold nanoparticles (GNPs) synthesized by pulsed laser ablation (PLA) method in Dulbecco’s Modified Eagle Medium (DMED), found to be located between (549-580) nm. The size of GNPs measured the calculation of SPR spectra, dynamic light scattering (DLS) methods and analysis of the transmission electron microscope (TEM) images were found to be ranged between (59-116) nm. The concentration of GNPs in prepared colloidal solution found ranged between (8-16) ppm. Irradiation of GNPs which incubated with Hela cells for 24 h by R light for (15,30, and 45) minutes, enhanced the killing percentage especially for GNPs diameters (50- 70) nm.

Highly effective and chemically stable surface enhanced Raman scattering substrates with flower-like 3D Ag-Au hetero-nanostructures

We demonstrated flower-like 3D Ag-Au hetero-nanostructures on an indium tin oxide glass (ITO glass) for surface enhanced Raman scattering (SERS) applications. The flower-like 3D Ag nanostructures were obtained through electrodeposition with liquid crystalline soft template which is simple, controllable and cost effective. The flower-like 3D Ag-Au hetero-nanostructures were further fabricated by galvanic replacement reaction of gold (III) chloride trihydrate (HAuCl4·3H2O) solution and flower-like Ag. The flower-like Ag-Au hetero-nanostructure exhibited stronger SERS effects and better chemical stability compared with flower-like Ag nanostructure. The localized surface plasmon resonance (LSPR) spectra, field emission scanning electron microscope (FESEM) photos and Ag-Au ratios were studied which show that the surface morphology and shape of the flower-like Ag-Au hetero-nanostructure play significant roles in enhancing SERS. The flower-like 3D Ag-Au hetero-nanostructures fabricated by electrodeposition in liquid crystalline template and galvanic replacement reaction are simple, cheap, controllable and chemical stable. It is a good candidate for applications in SERS detection and imaging.

Utilization of data classification in the realization of a surface Plasmon resonance readout system using an FPGA controlled RGB LED light source

This paper presents the realization of a surface plasmon resonance (SPR) sensor readout system using a tricolor red, green, and blue light emitting diode light source. Time domain intensity modulation of each color channel is applied to interrogate three bands of interest in the SPR spectrum using a single photodiode detector. A low computing resource classification approach is used through the combination of k-nearest neighbor (kNN) and adapted clustering using representative. An optimized number of representatives is chosen in the validation process to reduce the required amount of data for the kNN classification. This scheme was used to classify the concentrations of different glucose solutions. The sensor readout system hardware is based on the use of a field programmable gate array and the glucose solution classification is developed and undertaken on a personal computer using the Python open source programming language.

Study on surface plasmon-based improvement in absorption in plasmonic solar cell

Recently, plasmonics offers very high attention and greatly deals with various field includes the nanophotonics domain. In the plasmonic field, when the nanoparticle is much smaller than the wave length of light, coherent oscillation of the conduction band electrons induced by interaction with an electromagnetic field and conjointly improves absorption through scattering. In this paper, we studied the effectiveness of nanoparticle dimension to enhance extinction in terms of absorption and scattering for silver, gold, copper and aluminium nanoparticles. We also studied finite difference time domain-based solar cell model that improves various simulated plasmonic field components and observed that the high sensitivity of the surface plasmon resonance spectrum of noble metal nanoparticles to adsorbate induced changes in dimension and dielectric constant of the surrounding nanoenvironment. We also observed that noble metal specifically silver and gold nanoparticles significantly improve optical absorption than copper and aluminium nanoparticles.

Study on surface plasmon-based improvement in absorption in plasmonic solar cell

Recently, plasmonics offers very high attention and greatly deals with various field includes the nanophotonics domain. In the plasmonic field, when the nanoparticle is much smaller than the wave length of light, coherent oscillation of the conduction band electrons induced by interaction with an electromagnetic field and conjointly improves absorption through scattering. In this paper, we studied the effectiveness of nanoparticle dimension to enhance extinction in terms of absorption and scattering for silver, gold, copper and aluminium nanoparticles. We also studied finite difference time domain-based solar cell model that improves various simulated plasmonic field components and observed that the high sensitivity of the surface plasmon resonance spectrum of noble metal nanoparticles to adsorbate induced changes in dimension and dielectric constant of the surrounding nanoenvironment. We also observed that noble metal specifically silver and gold nanoparticles significantly improve optical absorption than copper and aluminium nanoparticles.

Insight on agglomerates of gold nanoparticles in glass based on surface plasmon resonance spectrum: study by multi-spheres T-matrix method

The formation of a localized surface plasmon resonance (SPR) spectrum of randomly distributed gold nanoparticles in the surface layer of silicate float glass, generated and implanted by UV ArF-excimer laser irradiation of a thin gold layer sputter-coated on the glass surface, was studied by the T-matrix method, which enables particle agglomeration to be taken into account. The experimental technique used is promising for the production of submicron patterns of plasmonic nanoparticles (given by laser masks or gratings) without damage to the glass surface. Analysis of the applicability of the multi-spheres T-matrix (MSTM) method to the studied material was performed through calculations of SPR characteristics for differently arranged and structured gold nanoparticles (gold nanoparticles in solution, particles pairs, and core–shell silver–gold nanoparticles) for which either experimental data or results of the modeling by other methods are available. For the studied gold nanoparticles in glass, it was revealed that the theoretical description of their SPR spectrum requires consideration of the plasmon coupling between particles, which can be done effectively by MSTM calculations. The obtained statistical distributions over particle sizes and over interparticle distances demonstrated the saturation behavior with respect to the number of particles under consideration, which enabled us to determine the effective aggregate of particles, sufficient to form the SPR spectrum. The suggested technique for the fitting of an experimental SPR spectrum of gold nanoparticles in glass by varying the geometrical parameters of the particles aggregate in the recurring calculations of spectrum by MSTM method enabled us to determine statistical characteristics of the aggregate: the average distance between particles, average size, and size distribution of the particles. The fitting strategy of the SPR spectrum presented here can be applied to nanoparticles of any nature and in various substances, and, in principle, can be extended for particles with non-spherical shapes, like ellipsoids, rod-like and other T-matrix-solvable shapes.

ANTIOXIDANT AND ANTICANCER POTENTIALS OF BIOFABRICATED SILVER NANOPARTICLES

Objective: The objective of this study is to explore a rapid, bio-inspired approach to synthesize silver nanoparticles (AgNPs) using aqueous Nardostachys jatamansi leaf extract and evaluate its antioxidant and cytotoxic activities on human colon carcinoma (HCT-116) cell lines.Methods: The biosynthesized nanoparticles were analyzed using ultraviolet-visible spectrophotometer, scanning electron microscope (SEM), energy dispersive X-ray, X-ray diffractometer (XRD), and Fourier transform infrared spectroscopy. Free radical scavenging and cytotoxic studies were carried out at different concentrations of AgNPs (20-100 μg/mL) using antioxidant 2,2-diphenyl-1-picrylhydrazil (DPPH) and mitochondrial function assay methods.Results: Surface plasmon resonance spectrum at 434 nm confirmed the formation of AgNPs. SEM images show biosynthesized AgNPs are mostly spherical shaped within the range of 30.0-58.7 nm. XRD analysis reveals the crystallographic face-centered cubic structure of the AgNPs. Thus, synthesized metal nanoparticles were tested for antioxidant activity by DPPH assay, and anticancer activity was validated by lactate dehydrogenase leakage assay. Significant antioxidant property was observed as compared to standard L-ascorbic acid. Further, AgNPs showed a linear dose-response relationship against HCT-116 cell lines with increasing concentration of AgNPs. At a concentration of 20 μg/mL, AgNPs were able to inhibit the cell line’s growth by less than 9.8 ± 0.7%, whereas 100 μg/mL of AgNPs significantly inhibited the cell line’s growth greater than 90.4 ± 0.25%.Conclusion: The synthesized AgNPs were found to be highly stable and had significant antioxidant and anticancer activity against HCT-116 cell lines. It has wide applications in the biomedical field and can be produced with eco-friendly, rapid scale-up, and easy downstream processing.

1-butanethiol vapor sensing based on gold nanoparticle immobilized on glass slide by digital color analysis

We demonstrate that gold nanoparticles (GNPs) immobilized on silanized glass act as an optical sensor that is able to quantify 1-butanethiol vapor. GNPs optical properties in the visible region are dominated by the surface plasmon resonance (SPR). The high affinity between 1-butanethiol and GNPs through Au-s bond leads to change in plasmon feature of GNPs that immobilized on silanized glass and causes absorption decrease at 542 nm in SPR spectrum of GNPs. It can be used as an optical sensor for quantitative detection.In this research, the glass slide surface activated by aminopropyltriethoxysilane (APTES). Spherical GNPs immobilized on silanized glass by silanization agent. The sensor is based on the spectrophotometry and digital color analysis (DCA) through RGB. We monitored R value and linear range 50–700 µM (R2 = 0.97) with 2.05% relative standard deviation and 26.5 µM value was achieved, for the limit of detection.This method represents advantages of metal gold nanoparticles and solid substrate stability in one package, being inexpensive and low time consuming is another advantage of our method that can be conducted in petrochemical, pharmaceutical industries, and for detection of rotten food in food industries.

Imaging the transient heat generation of individual nanostructures with a mechanoresponsive polymer

Measuring the localized transient heat generation is critical for developing applications of nanomaterials in areas of photothermal therapy (PTT), drug delivery, optomechanics and biological processes engineering. However, accurate thermometry with high spatiotemporal resolution is still a challenge. Here we develop a thermosensitive polymer-capped gold nanorod (AuNRs@pNIPAAm), which has temperature-dependent local surface plasmon resonance spectra due to the submolecular conformational change of pNIPAAm molecules. We measure the conformational dynamics on individual gold nanorods at the milliseconds level by the developed spatiotemporal resolution plasmonic spectroscopy (SRPS) and find that it has a fast (<4 ms), linear and reversible mechanoresponse to temperature changes as small as 80 mK. The rapid and highly sensitive thermosensitive AuNRs@pNIPAAm opens a new way to achieve spatiotemporal thermometry for potential applications in PTT and other biological research.

Probing Photothermal Effects on Optically Trapped Gold Nanorods by Simultaneous Plasmon Spectroscopy and Brownian Dynamics Analysis.

Plasmonic gold nanorods are prime candidates for a variety of biomedical, spectroscopy, data storage, and sensing applications. It was recently shown that gold nanorods optically trapped by a focused circularly polarized laser beam can function as extremely efficient nanoscopic rotary motors. The system holds promise for applications ranging from nanofluidic flow control and nanorobotics to biomolecular actuation and analysis. However, to fully exploit this potential, one needs to be able to control and understand heating effects associated with laser trapping. We investigated photothermal heating of individual rotating gold nanorods by simultaneously probing their localized surface plasmon resonance spectrum and rotational Brownian dynamics over extended periods of time. The data reveal an extremely slow nanoparticle reshaping process, involving migration of the order of a few hundred atoms per minute, for moderate laser powers and a trapping wavelength close to plasmon resonance. The plasmon spectroscopy and Brownian analysis allows for separate temperature estimates based on the refractive index and the viscosity of the water surrounding a trapped nanorod. We show that both measurements yield similar effective temperatures, which correspond to the actual temperature at a distance of the order 10-15 nm from the particle surface. Our results shed light on photothermal processes on the nanoscale and will be useful in evaluating the applicability and performance of nanorod motors and optically heated nanoparticles for a variety of applications.

In Situ Growth of Low-Dimensional Silver Nanoclusters with Their Tunable Plasmonic and Thermodynamic Behavior.

Optical properties of noble metal nanostructures associated with localized surface plasmon resonance (SPR) are technically important for optical switches and plasmonic devices. In this work, silver nanoclusters are embedded inside the soda-lime glass matrix, followed by a thermal annealing process in an open air atmosphere for 1 h. The effects of thermal annealing on the plasmonic behavior of Ag nanoclusters embedded in the glass matrix are studied with UV–vis spectroscopy and photoluminescence. In the SPR spectra, a 14 nm blue shift is observed in the visible range under the influence of thermal annealing at a higher temperature. The thermal effects on Ag particle size and SPR have been illustrated for plasmonic properties. The structural and elemental investigation of as-grown Ag nanoclusters is confirmed by X-ray diffraction, high-resolution transmission electron microscope, and X-ray photoelectron spectroscopy. The structural, plasmonic, and thermodynamic properties associated with the growth mechanism of Ag nanoclusters have been explained under the thermal process. Enthalpy (ΔH), entropy (ΔS), and Gibbs energy (ΔG) for Ag nanoclusters growth and nucleation are significantly calculated and interpreted at different temperatures. An empirical relation among the ΔH, ΔS, and ΔG is developed vis-a-vis activation energy (97.70 J/mol), which is calculated by the Arrhenius linear equation.

Dielectric over-layer assisted graphene, its oxide and MoS2-based fibre optic sensor with high field enhancement

A high-index fibre-core-based surface plasmon resonance (SPR) sensor using 2D materials such as graphene, graphene oxide (GO) and molybdenum disulphide (MoS2) on a silicon (Si) over-layer in visible and near infrared is reported. Si was used on silver (Ag) followed by different 2D materials of appropriate thickness on a 600 µm core multimode fibre. Here Si is used to tune the resonance to a higher wavelength, and different 2D materials are used to enhance the performance as well as address the oxidation problem of Si. Moreover, a high-index chalcogenide core helps to decrease the full width at half maxima of the SPR spectra, hence increasing the detection accuracy of the sensor. Both the Ag and Si thickness are optimized, and the effects of different 2D materials on the performance of sensor are studied using the transfer matrix method in terms of electric field intensity, sensitivity, figure of merit (FOM) and resolution. We found that the percentage electric field enhancement for the Ag–Si-GO system is 4.65 × 104 in the presence of GO. The GO-based sensor is found to have a sensitivity of 202.2 nm RIU−1 in comparison to the graphene based sensor with a sensitivity of 189.4 nm RIU−1. Moreover, the FOM values are found to be as high as 5.57 RIU−1 for GO, and 5.18 RIU−1 and 2.29 RIU−1 for the MoS2 and graphene respectively. We believe that the proposed 2D-material-based sensors will open a new window for the development of high-performance fibre biosensors by utilizing the biocompatibility aspect of different 2D materials along with its high electric field value in the presence of a dielectric over-layer.