Surface Plasmon Resonance Biosensor Research Articles

Plasmonic biosensor based on a gold nanostripe array for detection of microRNA related to myelodysplastic syndromes

We present a new optical biosensor based on surface plasmons excited on an array of gold nanostripes via attenuated total reflection. We investigate performance of the biosensor using a theoretical model that considers both optical and mass transport aspects. The analysis of optical aspects employs two different approaches: a complex model incorporating optical characteristics of the nanostructure as well as the noise characteristics of the optical readout system and a simple model based solely on the figure of merit of the nanostructure. The theoretical analysis suggests that the optimized biosensor is able to detect molecular analytes at concentrations lower by a factor of ~ 10 than conventional surface plasmon resonance biosensors. In order to validate the theoretical model, we characterize the gold nanostripe arrays of different designs in model refractometric and biosensing experiments. We show that the nanoplasmonic sensor exhibits refractive index sensitivity of 1989 nm/RIU and refractive index resolution down to 3.6×10−7RIU. In addition, we use the nanoplasmonic biosensor for the detection of a microRNA biomarker of myelodysplastic syndromes (miRNA-125b) and demonstrate that the biosensor can detect miRNA-125b at concentrations down to ~ 17 pM.

Gold-Immobilized Photonic Crystal Fiber-Based SPR Biosensor for Detection of Malaria Disease in Human Body

This article presents the photonic crystal fiber (PCF) based surface plasmon resonance (SPR) biosensor for early detection of malaria disease in humans by measurement of the variation of red blood cells (RBCs). In the proposed PCF, two layers of air holes are arranged in a hexagonal lattice structure and a thin film of gold-coating is used over PCF for the occurrence of SPR phenomena. It occurs when surface plasmon polariton (SPP)-mode coupled with the core-mode during phase-matching conditions. Malaria infected RBCs samples are filled into the PCF, which have own refractive index (RI) that shift the SPR resonance wavelength during confinement loss measurement. The resonance wavelength of malaria-infected RBCs samples is different from their normal RBCs samples due to the difference in RI of infected and normal RBCs samples. The proposed work is helpful in the detection of different stages of malaria-infected RBCs such as ring phase, trophozoite phase and Schizont phase by measuring the shift in resonance wavelength. The calculated wavelength sensitivities of the proposed sensor for the ring phase, trophozoite phase and Schizont phase RBCs are 13714.29 nm/RIU, 9789.47 nm/RIU, and 8068.97 nm/RIU, respectively in x-polarized direction and 14285.71 nm/RIU, 10000 nm/RIU, and 8206.9 nm/RIU, respectively in y-polarized direction with the maximum detection limit of 0.029. The proposed PCF-based SPR biosensor is suitable for the early diagnosis of malaria disease due to its enhanced sensing performance (low detection limit and high sensitivity).

Figure of merit enhancement of surface plasmon resonance biosensor based on Talbot effect

Figure of merit enhancement of surface plasmon resonance biosensor based on Talbot effect

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.

Surface plasmon resonance-based optical sensor using a thin layer of plasma

We propose a surface plasmon resonance (SPR) biosensor that consists of six layers: glass prism (SF 10), chromium, metal, molybdenum disulphide, graphene, and sensing medium. A seventh layer is added between the glass prism and the chromium layer, which is a gap filled with plasma as a dielectric material. The plasma layer is expected to carry the amenity of the graphene optical characteristics and absorption ability. It is also expected to improve sensitivity of the SPR structure. The numerical calculations show that the sensitivity of the sensor is 76.11 deg/RIU (refractive index unit); without the plasma layer, it can be improved to 103 deg/RIU in the presence of 25 and 35 nm thick plasma and silver layers, respectively. The structure parameters are optimized with respect to the sensitivity. The proposed sensor can potentially be used for biological purposes.

SPR biosensor using SnSe-phosphorene heterostructure

We numerically debrief a prism based SPR biosensor in this paper exploiting a single layer of Alfa-Tin Selenide (α-SnSe) that is not brought to light till today. This material exhibits incredible features with an analogous formation like graphene and phosphorene, and for this instance, a great contemplation is taken by the researchists utilizing a biomolecular recognition element (BRE) for modeling biosensors. The paper centers around the exploration of the effective advancement of surface plasmon resonance (SPR) biosensors by covering the gold (Au)/ silver (Ag)/ copper (Cu) layer with the α-SnSe monolayer. The proposed sensor consists of the structure of prism-(Au/Ag/Cu)-(α-SnSe)-Phosphorene-sensing medium. A dramatic sensitivity enhancement is reported by the analyses in the entire performance of this raised sensor while inserting an α-SnSe layer in between Au/Ag/Cu and phosphorene. The sensitivity for the proposed biosensors displays a maximal grade of 96.43 deg./RIU, 81.43 deg./RIU, and 74.29 deg./RIU for Au, Ag, and Cu based structures, respectively. It can be observed that the sensitivity of Au flourished biosensor is better than that of Ag or Cu based structures. Our outcomes also reveal that SPR sensors with α-SnSe monolayer can be utilized in demonstrative petitions, and their exalted sensitivity and little intentness of analyte are required. Consequently, the raised biosensor exhibits an in-mint condition ventilator in the direction of sensing petitions.

Sensitivity Enhancement of Surface Plasmon Resonance Biosensor with 2-D Franckeite Nanosheets

Sensitivity Enhancement of Surface Plasmon Resonance Biosensor with 2-D Franckeite Nanosheets

Theoretical analysis of sensitivity enhancement of surface plasmon resonance biosensor with zinc oxide and blue phosphorus/MoS2 heterostructure

In this paper, an ultrasensitive surface plasmon resonance (SPR) biosensor structure (CaF2 Prism /ZnO/Au/BlueP-MoS2/Sensing medium) based on angular interrogation technique has been studied to see the effect of Blue Phosphorus/MoS2 heterostructure with an adhesive layer of zinc oxide (ZnO). The adhesive layer is ZnO used between calcium fluoride (CaF2) prism and gold (Au) layer. Transfer matrix method is used for numerical analysis at operating wavelength 633 nm. The layers ZnO and Blue Phosphorus/MoS2 heterostructure are optimized to achieve the maximum sensitivity with minimum reflectance. The performance parameters, such as sensitivity (2280RIU−1), quality factor (56.211RIU−1), detection accuracy (0.2810), full width at half maximum (4.0561), and limit of detection (4.3859 × 10−6) are calculated for proposed SPR biosensor at room temperature. For two layers of BlueP/MoS2 heterostructure, the maximum sensitivity is 2350RIU−1. The result shows that the sensitivity of proposed structure is 17.5% greater as compared to the conventional structure. Transverse magnetic (TM) field is plotted, and the value of penetration depth is calculated as 145.25 nm for proposed SPR sensor. The proposed SPR sensor could be very useful in the SPR chip to detect biomolecules or analyte in visible range.

Recent Advancements in Aptamer-Based Surface Plasmon Resonance Biosensing Strategies.

Surface plasmon resonance (SPR) can track molecular interactions in real time, and is a powerful as well as widely used biological and chemical sensing technique. Among the different SPR-based sensing applications, aptamer-based SPR biosensors have attracted significant attention because of their simplicity, feasibility, and low cost for target detection. Continuous developments in SPR aptasensing research have led to the emergence of abundant technical and design concepts. To understand the recent advances in SPR for biosensing, this paper reviews SPR-based research from the last seven years based on different sensing-type strategies and sub-directions. The characteristics of various SPR-based applications are introduced. We hope that this review will guide the development of SPR aptamer sensors for healthcare.

DNA-facilitated target search by nucleoproteins: Extension of a biosensor-surface plasmon resonance method

To extend the value of biosensor-SPR in the characterization of DNA recognition by nucleoproteins, we report a comparative analysis of DNA-facilitated target search by two ETS-family transcription factors: Elk1 and ETV6. ETS domains represent an attractive system for developing biosensor-based techniques due to a broad range of physicochemical properties encoded within a highly conserved DNA-binding motif. Building on a biosensor approach in which the protein is quantitatively sequestered and presented to immobilized cognate DNA as nonspecific complexes, we assessed the impact of intrinsic cognate and nonspecific affinities on long-range (intersegmental) target search. The equilibrium constants of DNA-facilitated binding were sensitive to the intrinsic binding properties of the proteins such that their relative specificity for cognate DNA were reinforced when binding occurred by transfer vs. without nonspecific DNA. Direct measurement of association and dissociation kinetics revealed ionic features of the activated complex that evidenced DNA-facilitated dissociation, even though Elk1 and ETV6 harbor only a single DNA-binding surface. At salt concentrations that masked the effects of nonspecific pre-binding at equilibrium, the dissociation kinetics of cognate binding were nevertheless distinct from conditions under which nonspecific DNA was absent. These results further strengthen the significance of long-range DNA-facilitated translocation in the physiologic environment.

A High-Sensitivity SPR Sensor with Bimetal/Silicon/Two-Dimensional Material Structure: A Theoretical Analysis

In this paper, we reported a theoretical study of a novel Surface plasmon resonance (SPR) biosensor composed of BK7 prism, gold (Au)/silver (Ag) bimetallic layer, silicon and two-dimensional (2D) materials. The bimetallic layer combines the advantages of Au and Ag and the high refractive index silicon layer enhances the electric field on the surface of the sensor, so that the sensor has a better overall performance in terms of sensitivity and figure of merit (FOM). Compared with ordinary dielectrics, 2D materials have excellent photoelectric properties, such as larger specific surface area, higher carrier density and stronger adsorption capacity, which improve the detection ability of the sensor. The sensitivity of the optimized sensor achieves 297.2°/RIU, 274°/RIU and 246°/RIU when the silicon layer is covered with graphene, MXene (Ti3T2Cx) and MoS2, respectively. Compared with the traditional SPR sensor, the sensitivity of the structure has been significantly improved, and its excellent performance has broad application prospects in biosensing and other fields.

Surface plasmon resonance (SPR)-based biosensor using MXene as a BRE layer and magnesium oxide (MgO) as an adhesion layer

In this paper, a plasmonic sensor consists of a bimetallic layer of Ag and Au, a nano-thin layer of two-dimensional material MXene and a thin layer of Magnesium oxide (MgO) is proposed to operate in a visible region. Using Kretschmann configuration-based structure and transfer matrix method, the change in the refractive index of liquid Biosample have been observed at a fixed incident wavelength. Using the distinctive properties of Ti3C2Tx MXene and MgO, we have investigated the performance of Surface Plasmon Resonance (SPR) biosensor. Significant performance parameters such as Sensitivity, Figure of Merit (FoM) and Detection Accuracy (DA) calculated for different cases to prove the capability of proposed sensing structure. We also compared the sensitivity and sharpness of SPR curve obtained when using conventional adhesion layers such as titanium (Ti), chromium (Cr), and tantalum (Ta). A detailed investigation is carried out to observe the role of polymer as an adhesion layer and its thickness impact on FoM and resonance angle sharpness. The concept of Long range SPR (LR-SPR) and Short range SPR (SR-SPR) are also discussed.

Surface plasmon assisted toxic chemical NO<sub>2</sub> gas sensor by Au ∕ ZnO functional thin films

Abstract. In this short communication, we propose a surface plasmon resonance (SPR) sensor based on a ZnO / Au hybrid thin-film material structure and experimentally investigate its sensitivity improvement. The Kretschmann-based SPR sensor utilizes ZnO thin films and nanostructures for performance enhancement. The advancement in SPR technology relies on a low-cost, high-sensitivity, and high-selectivity sensor. Metal oxide (MO) has been incorporated into the SPR sensor to be used for detection of biological and chemical compounds. ZnO as one of the metal oxides is an attractive material due to its unique physical and optical properties. Numerous techniques for fabrication and characterization of ZnO on SPR gold substrate have been studied. The mechanism for gas and biomolecule detection depends on their interaction with the ZnO surface, which is mainly attributed to the high isoelectric point of ZnO. There are several types of ZnO nanostructures which have been employed for SPR application based on the Kretschmann configuration. In the future, the thin film and nanostructures of ZnO could be a potential application for miniature design, robust, high sensitivity, and a low-cost portable type of SPR biosensor to be used for on-site testing in a real-time and label-free manner. The present work includes the application of a developed SPR setup for gas sensing at room temperature using a specially designed gas cell. The change in the optical properties of dielectric layers (ZnO) with adsorption of gases (NO2) in order to develop an optical sensor has been presented. The obtained results emphasize the applications of an SPR setup for the study of interaction of adsorbed gas molecules, with dielectrics and gas sensing.

Measurement of Low Concentration of Micro-Plastics by Detection of Bioaffinity-Induced Particle Retention Using Surface Plasmon Resonance Biosensors.

The issue of micro-plastics is becoming more and more important due to their ubiquity and the harm they cause to the human body. Therefore, evaluating the biological–physical interaction of micro-plastics with health cells has become the focus of many research efforts. This study focuses on the movement mode and low concentration detection development for micro-plastics in surface plasmon resonance (SPR). Firstly, 20-micrometer micro-plastics were prepared by grinding and filtering, and the movement mode was explored; then, the characteristics were investigated by SPR. Chromatographic analysis showed that the surface charge of micro-plastics dominated the elution time, and estrogen receptors (ERs) played a supporting role. A difference of micro-plastics in SPR sensorgram was observed, inferring the micro-plastics’ movement in rolling mode on the ERs. Characteristics analysis indicated that the low particle number of micro-plastics on SPR showed a linear relationship with the response unit (RU). When ERs were immobilized on the biosensor, the force of the binding of micro-plastics to ERs under an ultra-low background was equivalent to the dissociation rate constant shown as follows: PS (0.05 nM) > PVC (0.09 nM) > PE (0.14 nM). The ELISA-like magnetic beads experiment verified the specificity between ERs and micro-plastics. Therefore, by using the SPR technique, a biological-derived over-occupation of PS was found via higher binding force with ERs and longer retention time. In the future, there will be considerable potential for micro-plastics issues, such as identification in natural samples, biomarking, real-time detection in specific environments/regions and human health subject.

In vivo liquid biopsy for glioblastoma malignancy by the AFM and LSPR based sensing of exosomal CD44 and CD133 in a mouse model

Glioblastoma (GBM) is the fatal brain tumor in which secreted lactate enhances the expression of cluster of differentiation 44 (CD44) and the release of exosomes, cell-derived nanovesicles (30–200 nm), and therefore promotes tumor malignant progression. This study found that lactate-driven upregulated CD44 in malignant Glioblastoma cells (GMs) enhanced the release of CD44-enriched exosomes which increased GMs' migration and endothelial cells’ tube formation, and CD44 in the secreted exosomes was sensitively detected by “capture and sensing” Titanium Nitride (TiN) - Nanoholes (NH) - discs immunocapture (TIC) - atomic force microscopy (AFM) and ultrasensitive TiN–NH-localized surface plasmon resonance (LSPR) biosensors. The limit of detection for exosomal CD44 with TIC-AFM- and TiN–NH-LSPR-biosensors was 5.29 × 10-1 μg/ml and 3.46 × 10-3 μg/ml in exosome concentration, respectively. Importantly, this work first found that label-free sensitive TiN–NH-LSPR biosensor could detect and quantify enhanced CD44 and CD133 levels in immunocaptured GMs-derived exosomes in the blood and the cerebrospinal fluid of a mouse model of GBM, supporting its potential application in a minimally invasive molecular diagnostic for GBM progression as liquid biopsy.

Simulation of the improvement in the performance of a silver-based surface plasmon resonance biosensor using experimental results of cold plasma treatment of glass substrate

In this study, the effect of observed pinholes in the Field emission scanning electron microscopy (FESEM) images on the performance of a silver-based surface plasmon resonance (SPR) biosensor is designed and analytically investigated by a finite element method using COMSOL multiphysics. The simulation results show that the sensitivity and figure of merit (FOM) enhancement of biosensor is attributed to the cold atmospheric-pressure plasma (CAP) treatment of glass substrate before deposition; leading to the omission of pinholes. This work is proposing a new way for SPR biosensors development using surface quality control of the deposited thin films with CAP treatment.

Highly sensitive crumpled 2D material-based plasmonic biosensors.

We propose surface plasmon resonance biosensors based on crumpled graphene and molybdenum disulphide (MoS2) flakes supported on stretchable polydimethylsiloxane (PDMS) or silicon substrates. Accumulation of specific biomarkers resulting in measurable shifts in the resonance wavelength of the plasmon modes of two-dimensional (2D) material structures, with crumpled structures demonstrating large refractive index shifts. Using theoretical calculations based on the semiclassical Drude model, combined with the finite element method, we demonstrate that the interaction between the surface plasmons of crumpled graphene/MoS2 layers and the surrounding analyte results in high sensitivity to biomarker driven refractive index shifts, up to 7499 nm/RIU for structures supported on silicon substrates. We can achieve a high figure of merit (FOM), defined as the ratio of the refractive index sensitivity to the full width at half maximum of the resonant peak, of approximately 62.5 RIU-1. Furthermore, the sensing properties of the device can be tuned by varying crumple period and aspect ratio through simple stretching and integrating material interlayers. By stacking multiple 2D materials in heterostructures supported on the PDMS layer, we produced hybrid plasmon resonances detuned from the PDMS absorbance region allowing higher sensitivity and FOM compared to pure crumpled graphene structures on the PDMS substrates. The high sensitivity and broad mechanical tunability of these crumpled 2D material biosensors considerable advantages over traditional refractive index sensors, providing a new platform for ultrasensitive biosensing.

Sensitivity Analysis of Single- and Bimetallic Surface Plasmon Resonance Biosensors.

Comparative analysis of the sensitivity of two surface plasmon resonance (SPR) biosensors was conducted on a single-metallic Au sensor and bimetallic Ag–Au sensor, using a cathepsin S sensor as an example. Numerically modeled resonance curves of Au and Ag–Au layers, with parameters verified by the results of experimental reflectance measurement of real-life systems, were used for the analysis of these sensors. Mutual relationships were determined between ∂Y/∂n components of sensitivity of the Y signal in the SPR measurement to change the refractive index n of the near-surface sensing layer and ∂n/∂c sensitivity of refractive index n to change the analyte’s concentration, c, for both types of sensors. Obtained results were related to experimentally determined calibration curves of both sensors. A characteristic feature arising from the comparison of calibration curves is the similar level of Au and Ag–Au biosensors’ sensitivity in the linear range, where the signal of the AgAu sensor is at a level several times greater. It was shown that the influence of sensing surface morphology on the ∂n/∂c sensitivity component had to be incorporated to explain the features of calibration curves of sensors. The shape of the sensory surface relief was proposed to increase the sensor sensitivity at low analyte concentrations.

On the Use of Surface Plasmon Resonance Biosensing to Understand IgG-FcγR Interactions.

Surface plasmon resonance (SPR)-based optical biosensors offer real-time and label-free analysis of protein interactions, which has extensively contributed to the discovery and development of therapeutic monoclonal antibodies (mAbs). As the biopharmaceutical market for these biologics and their biosimilars is rapidly growing, the role of SPR biosensors in drug discovery and quality assessment is becoming increasingly prominent. One of the critical quality attributes of mAbs is the N-glycosylation of their Fc region. Other than providing stability to the antibody, the Fc N-glycosylation influences immunoglobulin G (IgG) interactions with the Fcγ receptors (FcγRs), modulating the immune response. Over the past two decades, several studies have relied on SPR-based assays to characterize the influence of N-glycosylation upon the IgG-FcγR interactions. While these studies have unveiled key information, many conclusions are still debated in the literature. These discrepancies can be, in part, attributed to the design of the reported SPR-based assays as well as the methodology applied to SPR data analysis. In fact, the SPR biosensor best practices have evolved over the years, and several biases have been pointed out in the development of experimental SPR protocols. In parallel, newly developed algorithms and data analysis methods now allow taking into consideration complex biomolecular kinetics. In this review, we detail the use of different SPR biosensing approaches for characterizing the IgG-FcγR interactions, highlighting their merit and inherent experimental complexity. Furthermore, we review the latest SPR-derived conclusions on the influence of the N-glycosylation upon the IgG-FcγR interactions and underline the differences and similarities across the literature. Finally, we explore new avenues taking advantage of novel computational analysis of SPR results as well as the latest strategies to control the glycoprofile of mAbs during production, which could lead to a better understanding and modelling of the IgG-FcγRs interactions.

Surface plasmon resonance biosensor for the detection of miRNAs by combining the advantages of homogeneous reaction and heterogeneous detection

The hybridization and enzymolysis reactions for nucleic acid detection were carried out on the chip surface in the traditional surface plasmon resonance (SPR) biosensors. Herein, we proposed an innovative method for microRNA (miRNA) detection in which the hybridization-enzymolysis recycling reactions were performed in solution. Duplex-specific nuclease (DSN) and streptavidin-modified gold nanoparticles (SA-AuNPs) were employed for enhancing the assay sensitivity. In the absence of miRNA, the biotinylated DNA probe (bio-DNA-bio, biotin tags at both the 3′ and 5′ termini of DNA) was attached to the SA-modified chip through the SA-biotin binding, allowing the capture of SA-AuNPs with the same interaction. As a result, a larger SPR signal was attained. However, in the presence of miRNA, bio-DNA-bio hybridized with miRNA was digested by DSN. In this process, the miRNA strand remained intact and participated in the next hybridization-enzymolysis recycling process. Thus, one miRNA could promote the hydrolysis of many bio-DNA-bio probes and allow the generation of numerous bio-DNA fragments. Meanwhile, the produced bio-DNA competed with the undigested bio-DNA-bio to bind SA on the chip surface. The digestion of bio-DNA-bio and the competitive binding between bio-DNA-bio and bio-DNA led to the attachment of fewer SA-AuNPs and then smaller SPR signals. The change in SPR signal at the concentration as low as 1 fM miRNA has been readily determined. The strategy possessed the advantageous properties of simple operation, fast response, high sensitivity and excellent specificity, serving as a viable means for the fabrication of novel sensing platforms.