Sensitive Surface Plasmon Resonance Research Articles

Rapid and Sensitive Detection by Combining Electric Field Effects and Surface Plasmon Resonance: A Theoretical Study.

Surface plasmon resonance (SPR) has been extensively employed in biological sensing, environmental detection, as well as chemical industry. Nevertheless, the performance possessed by conventional surface plasmon resonance (SPR) biosensors can be further limited by the transport of analyte molecules to the sensing surface, noteworthily when small molecules or low levels of substances are being detected. In this study, a rapid and highly sensitive SPR biosensor is introduced to enhance the ability of the target analytes' collection by integrating AC electroosmosis (ACEO) and dielectrophoresis (DEP). Both the above-mentioned phenomena principally arise from the generation of the AC electric fields. This generation can be tailored by shaping the interdigitated electrodes (IDEs) that also serve as the SPR biomarker sensing area. The effects exerted by different parameters (e.g., the frequency and voltage of the AC electric field as well as microelectrode structures) are considered in the iSPR (interdigitated SPR) biosensor operation, and the iSPR biosensors are optimized with the sensitivity. The results of this study confirm that the iSPR can efficiently concentrate small molecules into the SPR sensing area, such that SPR reactions achieve an order of magnitude increase, and the detection time is shortened. The rapid and sensitive sensor takes on critical significance in the development of on-site diagnostics in a wide variety of human and animal health applications.

Design of a highly sensitive and precise long-range surface plasmon resonance sensor for early detection of malaria

This manuscript presents an innovative Kretschmann configured for Long Range Surface Plasmon Resonance (LRSPR) sensor for malaria detection. It utilizes tungsten diselenide (WSe2) as a bio+molecular recognition element (BRE) layer to attach target analyte. The optimized sensor design demonstrates exceptional performance in detecting different malaria stages (Schizont with refractive index (RI) = 1.371, Trophozoite with RI = 1.381, and Ring with RI = 1.396) at a 633 nm wavelength. In comparison to conventional surface plasmon resonance (CSPR), the LRSPR biosensor exhibits a substantial improvement, a 6.67 to 10 times increase in detection accuracy (DA), an impressive 40 to 86.55 times enhancement in imaging figure of merit (IFOM), and a 6.0 to 8.66 times boost in imaging sensitivity (Simg.) for the sequential detection of different stages of malaria. COMSOL Multiphysics simulations highlight a deeper penetration depth (PD) of 258.71 nm, 276.85 nm, and 373.04 nm for the detection of Schizont, Trophozoite, and Ring stages, respectively.

The effect of surface roughness on the performance of 3D printed surface plasmon resonance sensors for refractive index measurements

AbstractIn this study, a polymer-based surface plasmon resonance (SPR) sensor for refractive index measurements was designed and manufactured via inkjet 3D printing; then, it was optically characterized. Next, it was investigated how the surface finish of the 3D printed optical waveguide affects the sensor performance, i.e., its sensitivity. More in detail, it was studied how the surface roughness changes with the placement of the 3D printed items on the building platform. To achieve this purpose, a Phase I distribution-free quality monitoring analysis of the selected manufacturing process was implemented for a small pilot production run. The aim was to check the stability of surface roughness versus the placement of the 3D printed parts on the building platform. The 3D printed sensor’s surface roughness was assessed through a profilometry study. In particular, the surface roughness was determined for the core of the optical waveguide used to excite the SPR phenomena. Furthermore, the SPR sensors were optically characterized to find the existing relationship between their sensitivity and the considered quality of surface finish. In particular, by varying the surface roughness of the used waveguide, the light scattering in the waveguide changes, and the SPR sensitivity changes too, similarly to the light-diffusing fibers covered by gold nanofilms where the guided light is scattered through a plurality of voids distributed in the core. The procedure followed to investigate the sensor roughness, and establishing their performance enabled the optimal operative range for their application in practice to be identified. Finally, a better knowledge of the 3D printing manufacturing process has been achieved to improve quality of surface finish.

Sensitive surface plasmon resonance biosensor by optimized carboxylate functionalized carbon nanotubes/chitosan for amlodipine detecting

The adoption of biophotonic sensing technologies holds significant promise for application in health care and biomedical industries in all aspects of human life. Then, this piece of writing employs the powerful effective medium theory and FDTD simulation to anticipate the most favorable state and plasmonic attributes of a magnificent nanocomposite, comprising carboxylate functionalized carbon nanotubes and chitosan (CS). Furthermore, it thoroughly explores the exhibited surface plasmon resonance behaviors of this composite versus the quantity of CS variation. Subsequently, enlightening simulations are conducted on the nanocomposite with a delicate layer and a modified golden structure integrating as a composite. The intricate simulations eventually unveil an optimal combination to pave the way for crafting an exceptional specific biosensor that far surpasses its counterpart as a mere Au thin layer in terms of excellence. The proposed biosensor demonstrated linear behavior across a wide range from 0.01 μM to 150 μM and achieved a detection limit of 10 nM, with a sensitivity of 134◦RIU−1.

Facile green synthesis of silver nanoparticles: Relevance in localized surface plasmon resonance and molecular imprinted polymer sensor for detection of Tetrabromobisphenol A in electronic waste

The present study demonstrates evocatively the interest in prioritizing an environmental friendly approach. Green synthesis of metallic nano-particles is carried out, which is further incorporated with a technique known as Molecular Imprinted Polymers (MIP) to develop a highly sensitive cuvette-based localized surface plasmon resonance (LSPR) probe for the selective detection of a Tetrabromobisphenol-A (TBBPA). TBBPA is a hazardous phenolic compound, mostly found in electronic waste (E-waste), that is abundant on earth. We have fabricated an LSPR probe with the help of a transparent glass substrate. A layer of Silver nanoparticles has been decorated over the glass substrate which further has an MIP overlayer on it. The glass slide dimensions are so chosen that it can fit inside the cuvette along its one side. The absorbance spectra are then recorded for a concentration range of 0–500 ng/ml of TBBPA. The sensitivity and limit of detection of the proposed sensor have been found to be 0.228 nm/ng ml−1 and 4.68 ng/ml respectively. Also, the probe showed quite promising recovery percentage greater than 85 % in real samples. Hence, with the findings and outcomes our fabricated probe can be represented as a potential candidate in selective detection of TBBPA along with the benefits of low cost of fabrication, portable, and real-time monitoring.

Coffee Ring Effect Enhanced Surface Plasmon Resonance Imaging Biosensor via 2-λ Fitting Detection Method.

SPR biosensors have been extensively used for investigating protein-protein interactions. However, in conventional surface plasmon resonance (SPR) biosensors, detection is limited by the Brownian-motion-governed diffusion process of sample molecules in the sensor chip, which makes it challenging to detect biomolecule interactions at ultra-low concentrations. Here, we propose a highly sensitive SPR imaging biosensor which exploits the coffee ring effect (CRE) for in situ enrichment of molecules on the sensing surface. In addition, we designed a wavelength modulation system utilizing two LEDs to reduce the system cost and enhance the detection speed. Furthermore, a detection limit of 213 fM is achieved, which amounts to an approximately 365 times improvement compared to traditional SPR biosensors. With further development, we believe that this SPR imaging system with high sensitivity, less sample consumption, and faster detection speed can be readily applied to ultra-low-concentration molecular detection and interaction analysis.

Abstract LB030: Building a platform of validated high throughput screening approaches for molecular glue degrader identification

Abstract Over recent years, Induced proximity therapeutics (IPT) and targeted protein degradation (TPD) approaches have become increasingly popular. Whilst significant initial efforts focused upon heterobifunctional degraders, molecular glue degraders (MGDs) represent the next generation proximity-based drugs, but their rational discovery remains challenging. Here, we describe unbiased and broadly applicable approaches for molecular glue hit ID through the development of a suite of orthogonal and highly complementary screening approaches, relying on Homogeneous Time-Resolved Fluorescence (HTRF), Surface Plasmon Resonance (SPR) and High Content Imaging (HCI). To demonstrate the utility of these assays, we have focussed on the therapeutically relevant protein SOS1 as a model target. SOS1 is the major guanine nucleotide exchange factor (GEF) for KRAS, where inhibition of the SOS1/KRAS interaction reduces tumor growth in preclinical settings, and small molecule inhibitors of the SOS1/KRAS interaction are currently undergoing clinical testing for KRAS driven cancers. Our HTRF approach measures the induced interaction between the ubiquitin ligase CRBN/DDB1 and the SOS1 protein. The assay was successfully developed and validated in a miniaturized format utilizing a bifunctional tool compound as a positive control. Complementing our HTRF based approach, we also developed a highly sensitive SPR assay for detecting compounds that generate a ternary complex with CRBN/DDB1. These assay formats are amenable for large scale HTS screening, and as proof-of-concept we have established workflows and screened compound collections from the Sygnature LeadFinder and fragment libraries, in each of these assay platforms. Our combined biochemical/biophysical approach to glue identification using HTRF and SPR demonstrates the successful and scalable use of these methodologies for HTS, with the exciting potential for identification of novel MGD candidates for SOS1. To further complement these strategies for glue identification, we have additionally developed a functional cell-based approach utilizing HCI. HCI offers a medium-high throughput approach to monitor endogenous protein abundance and localization in complex cellular models. One major advantage of imaging assays is that they are amenable to multiplexing, allowing simultaneous detection of target engagement, biomarker analysis and compound toxicity. Here, we showcase HCI as a robust, high throughput method of screening for induced protein degradation at the endogenous level, again focusing on the KRAS pathway. Using this approach we quantified endogenous protein abundance in response to compound treatment, as well as downstream effects in the RAS pathway. Together, these approaches demonstrate multiple, complementary options for identifying molecular glue degraders. Further, the described assays are also applicable for screening and characterization of bifunctional degrader compounds. This platform is poised to identify high quality lead compounds across a range of oncology targets in areas of unmet clinical need. Citation Format: Allan Jordan, Philip Addis, Toby Allen, Tarun Ayra, Sarah Beck, Roslyn Brant, Roland Hjerpe, Benoit Gourdet, Martin Jennings, Rachel Lawrence, Sigrun Campbell-Maurer, Pei Cing Ng, Lyn Parkinson, Eva Rejnowicz, Gonzalo Robles, Elizabeth Rosethorne, Joshua Shaw, Duncan Smith, Denise Swift, Daniel Tait, Stuart Thomson, Chris Tomlinson, Ailsa Townley, Stephanie Ward, Clare Wilson. Building a platform of validated high throughput screening approaches for molecular glue degrader identification [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(7_Suppl):Abstract nr LB030.

High sensitive optical fiber SPR sensor for label-free detection of Staphylococcus aureus

Optical fiber bacterial sensors have attracted attention in many fields due to their unique advantages. However, it is still difficult to promote its practicality which is mainly subject to their low sensitivity, inferior stability, and reliability. This work reported here an optical fiber surface plasmon resonance (SPR) biosensor enhanced by gold nanoparticles (AuNPs)/Au film coupling for label-free detection the Staphylococcus aureus (S. aureus), while both the gold substrates were successfully biofunctionalized with goat anti-human immunoglobulin G (IgG) as the probe to capture and detect the bacteria. In the experiment, the refractive index（RI） sensitivity of the Multimode-Singlemode-Multimode optical fiber (MSMOF) coated with Au film was improved by 19 % after the AuNPs were homogeneously decorated on the Au film surface. To detect S. aureus by the sensor, the SPR wavelength variation in the transmission spectrum was recorded, and its limit of detection (LOD) was demonstrated experimentally to be about 50 CFU/mL and was obtained theoretically to be 1.18 CFU/mL during its concentration range of 50–108 CFU/mL. Also, it shows great linearity in the range of 102-108 CFU/mL and the sensor exhibits excellent specificity and stability. This kind of SPR-enhanced optical fiber biosensor is fully promising for its applications in biomedicine, food safety, pharmaceuticals, etc.

Modeling and analysis of discrete particle detection in wide-field surface plasmon resonance microscopy

Wide-field surface plasmon resonance microscopy (WF-SPRM), based on Kretschmann’s configuration, is a powerful technique for detecting nano-objects in solution. In this study, key parameters for building a highly sensitive WF-SPRM are optimized, including laser wavelength, prism refractive index, numerical aperture of the objective, and gold layer thickness. A medium model describes the surface plasmon resonance (SPR) sensor principle, treating molecules bound on the sensor surface as an effective medium with an effective refractive index and thickness. On the other hand, the SPR discrete particle model is introduced to describe the detection principle for discrete particles. Theoretical, numerical, and experimental analyses are conducted, and the calculated intensity profiles of single and double nanoparticles from the discrete particle model describe the experimental profiles well. Furthermore, the influence of coating the gold layer with a dielectric layer on the SPR sensitivity is investigated for varying refractive indices.

Au-Pt alloy nanoislands for highly sensitive localized surface plasmon resonance sensing of antimony(III) ions

Alloy nanomaterials exhibit superior plasmonic properties that can exceed traditional single-metal nanomaterials. Hence, they hold great potential for developing highly sensitive sensors capable of detecting small analytes in nanoscale. The self-assembly Au-Pt alloy nanoislands structure is used, for the first time, for localized surface plasmon resonance sensing. Its nanostructure has been studied and characterized by using various microscopy and spectroscopy techniques. It was found that Au0.94-Pt0.06 was the optimum composition with the best sensitivity toward the change of refractive index over various concentrations of NaCl solution and double the sensitivity than that of pure Au nanoislands. The Au-Pt chip with its surface functionalized with nitrotyrosine was successfully developed for highly sensitive detection of antimony (III) ion, the electronic properties of the interaction between nitrotyrosine and Sb during the biosensing was explored using density functional theory simulation to explain their strong adsorption to make nitrotyrosine a successful receptor. The sensor achieved a limit of detection of 0.0504 ppb, which is the best ever value among all those reported for Sb(III) ions sensing. With its high selectivity tested among 14 other common elements, the present Sb(III) ion LSPR sensor also possesses attributes of label-free, easy to fabricate and simple to operate.

High sensitivity fiber SPR sensor based on InSe nanosheets and Au nanoparticles

Surface Plasmon Resonance (SPR) fiber sensors are widely used in the field of biosensing. However, there are still issues of low sensitivity and poor stability in practical detection processes. This paper proposes a highly sensitive fiber SPR sensor based on InSe nanosheets and Au nanoparticles. This paper investigates the enhancement effects of different thicknesses of InSe films inserted between the Au film and the fiber and the adsorption of Au nanoparticles on the Au film surface of the fiber-InSe-Au sensor. The sensitivity of the fiber-InSe-Au sensor reaches 5534.76 nm/RIU, which is 2.71 times higher than the fiber-Au sensor and a 22% improvement compared to the fiber-Au-InSe sensor. The sensitivity of the fiber-InSe-Au-AuNPs sensor further increases to 5853.75, and the FOM reaches 28.11, a 47% improvement compared to the fiber-InSe-Au sensor. Moreover, the enhancement substance is situated within the Au film, which enhances the sensor's stability. Additionally, due to the low biotoxicity and high biocompatibility of Au nanoparticles, the high-performance sensor designed in this study is exceptionally well-suited for biosensing applications.

Highly sensitive gamma ray dosimeter based on dual-core photonic crystal fiber

This paper introduces the application of a photonic crystal fiber (PCF) sensor to be used as a gamma ray dosimeter. This paper proposes an efficient analysis of a highly sensitive surface Plasmon resonance for gamma ray dose detection in nuclear research reactors. The proposed structure makes use of a Poly-Vinyl Alcohol (PVA) polymer, which has high sensitivity to an external electric field and gamma rays making it suitable for nuclear reactor applications. At resonance frequency, the peak of spectral loss for dosimeter sensors refers to gamma irradiation dose values. Therefore, study the different geometrical parameters for the proposed PCF sensor is of significant importance to achieve high sensitivity with low spectral losses. The full-vectorial finite-element method has been used for analysis with the plane wave expansion method. The sensitivity of the suggested sensor achieves up to 0.006 µm per gamma-ray dose unit (μm/Gy) with low losses.

Surface-Plasmon-Resonance Amplification of FMD Detection through Dendrimer Conjugation.

The amplification of the surface plasmon resonance (SPR) sensitivity for the foot-and-mouth disease (FMD) detection was studied using Poly(amidoamine) (PAMAM) succinamic-acid dendrimers. The dendrimers were conjugated with the complementary annealed with the aptamers capable of binding specifically to FMD peptides. The tethered layer of the dendrimer-conjugated double-stranded(ds)-aptamers was formed on the SPR sensor Au surface via a thiol bond between the aptamers and Au. After the tethered layer was formed, the surface was taken out of the SPR equipment. Then, the ds-aptamers on the surface were denatured to collect the dendrimer-conjugated single-stranded(ss)-complementary. The surface with only the remaining ss-aptamers was transferred again to the equipment. Two types of the injections, the FMD peptide only and the dendrimer-conjugated ss-complementary followed by the FMD peptides, were performed on the surface. The sensitivity was increased 20 times with the conjugation of the dendrimers, but the binding rate of the peptides became more than two times slower.

Controllable synthesis of multi-tip spatial gold nanostructures to facilitate SPR enhancement for exosomal PD-L1 assay

A surface plasmon resonance (SPR) biosensor was developed utilizing gold nanoflowers with multi-tip tiny petals (Au@Au mNFs) and multifunctional peptides for the selective detection of exosomal programmed cell death 1 ligand 1 (ExoPD-L1). In the presence of different salt concentrations, DNA-functionalized gold seeds underwent in situ gold growth, resulting in Au@Au NFs with varying numbers of petals or Au@Au nanospheres (Au@Au NSs). The growth orientation of the gold shells was influenced by the “upright”, “tilted” or “lying” state of the DNA on the gold core surface, depending on the salt concentration solution. The finally prepared Au@Au mNFs exhibited a multi-tip spatial structure, which served as a highly efficient SPR sensitized layer with abundant hot spots on the gold film surface. The enhanced SPR sensitivity was attributed to the substantial electromagnetic field enhancement generated at the tips of the mNFs. By achieving suitable surface coverage of the multifunctional peptide at the sensing interface constructed by Au@Au mNFs, efficient capture of ExoPD-L1 was ensured. The analysis results demonstrated that the developed SPR sensor successfully detected ExoPD-L1 within a concentration range of 10–107 particles/mL, with a detection limit of 4.95 particles/mL. This work highlights the significant improvement in SPR sensing and detection performance achieved by utilizing Au@Au mNFs with multi-tip spatial nanostructures, providing a straightforward approach for achieving ultra-sensitive detection of target substances through SPR.

High refractive index sensing highly sensitive and low loss SPR sensor based on hollow-core D-shaped optical fiber

A hollow-core D-shaped optical fiber-based surface plasmon resonance (SPR) sensor for low-loss and highly sensitive liquid analytes detection is theoretically investigated. The gold (Au) metal nanolayer is coated on the cladding etched D-shaped flat surface to develop the plasmonic effect. The nanolayer coating on the outer flat surface is very easy compared to the inside hollow-core, so our hollow-core sensor manufacturing is too easy compared to other hollow-core refractive indices (RIs) detection sensors. The resonance effect between analytes filled fundamental guided core mode and surface plasmon polariton mode of the D-shaped hollow-core optical fiber sensor is used to obtain the detections of analytes RIs variations. We have found good linear results ([Formula: see text]) in analytes RIs versus resonance wavelength for gold layers thicknesses for the analytes RIs range of 1.45–1.52. This hollow-core D-shaped optical fiber sensor achieves the maximum wavelength sensitivity of 23500[Formula: see text]nm RIU[Formula: see text] and a corresponding resolution of [Formula: see text] RIU. We have obtained the maximum figure of merit (FOM) of 228 1/RIU. The proposed sensor may be highly active in detecting the biological and chemical liquid analytes.

Design and Modeling of a Novel Highly Sensitive Surface Plasmon Resonance Sensor Applying Tin Selenide and Graphene for Cancer Detection

Design and Modeling of a Novel Highly Sensitive Surface Plasmon Resonance Sensor Applying Tin Selenide and Graphene for Cancer Detection

Theoretical Modeling of Surface Plasmon Resonance Biosensor Using Titanium Dioxide and Graphene Nanomaterial for Refractive Index Sensing

The most popular method to determine the sensitivity of surface plasmon resonance (SPR) sensors in the last couple of decades has been angular interrogation. The silver layer (Ag), a 2D layer of TiO2, and dielectric material layer such as silicon (Si) with heterostructure material graphene are all stacked in the proposed SPR sensor. To increase sensitivity of SPR sensor in the visible area, the device structure focuses on the Kretschmann configuration, by which a TiO2 sheet is sandwiched between silver and silicon sheets. The proposed device structure makes use of the operational wavelength of 633 nm. The numerical simulation has been performed in MATLAB software in this device structure. The simulation results show that an analyte of refractive indices ranges 1.345–1.350. A single layer of silicon 3 nm and TiO2 10 nm makes up the suggested SPR configuration, which increases the sensitivity to 281° RIU−1. Herein, it has also been computed the figure of merit, detection accuracy, limit of detection, full width at half maximum, and transverse magnetic electric field intensity. The biomedical and chemical fields have benefited from the proposed SPR sensor structure design.

Sensitive and selective Cu2+ detection via surface plasmon resonance using ionophore decorated nanocrystalline cellulose-graphene oxide thin film

In this work, highly sensitive and selective surface plasmon resonance (SPR) sensor has been developed using nanocrystalline cellulose-graphene oxide-ionophore (NCC-GO-ionophore) for copper ion (Cu2+) detection. By incorporating SPR with nanocrystalline cellulose-graphene oxide-ionophore (NCC-GO-ionophore) thin film, Cu2+ was able to be detected as low as 0.001 ppm until 0.1 ppm. Moreover, the results show that the NCC-GO-ionophore thin film has good sensitivity towards Cu2+ with sensitivity value of 59.9150° ppm−1 from 0.001 to 0.01 ppm and 2.2261° ppm−1 from 0.01 to 0.1 ppm. Besides that, the developed sensor also shows high affinity towards Cu2+ compared to other metal ions. Using the Langmuir isotherm model, the binding affinity constant, K was calculated i.e., 6.881 × 103 M−1. Furthermore, the ability of the sensor to detect Cu2+ in spiked river water sample was also investigated where Cu2+ as low as 0.5 until 100 ppm can be determined. This result shows that the sensor has high sensitivity and selectivity towards Cu2+ detection.

A New Dawn for Targeted Cancer Therapy: Small Molecule Covalent Binding Inhibitor Targeting K-Ras (G12C).

K-Ras is a frequently mutated oncogene in human malignancies, and the development of inhibitors targeting various oncogenic K-Ras mutant proteins is a major challenge in targeted cancer therapy, especially K-Ras(G12C) is the most common mutant, which occurs in pancreatic ductal adenocarcinoma (PDAC), non-small cell lung cancer (NSCLC), colorectal cancer (CRC) and other highly prevalent malignancies. In recent years, significant progress has been made in developing small molecule covalent inhibitors targeting K-Ras(G12C), thanks to the production of nucleophilic cysteine by the G12C mutant, breaking the "spell" that K-Ras protein cannot be used as a drug target. With the successful launch of sotorasib and adagrasib, the development of small molecule inhibitors targeting various K-Ras mutants has continued to gain momentum. In recent years, with the popularization of highly sensitive surface plasmon resonance (SPR) technology, fragment-based drug design strategies have shown great potential in the development of small molecule inhibitors targeting K-Ras(G12C), but with the increasing number of clinically reported acquired drug resistance, addressing inhibitor resistance has gradually become the focus of this field, indirectly indicating that such small molecule inhibitors still the potential for the development of these small molecule inhibitors are also indirectly indicated. This paper traces the development of small molecule covalent inhibitors targeting K-Ras(G12C), highlighting and analyzing the structural evolution and optimization process of each series of inhibitors and the previous inhibitor design methods and strategies, as well as their common problems and general solutions, in order to provide inspiration and help to the subsequent researchers.

Sensitive Aluminum SPR Sensors Prepared by Thermal Evaporation Deposition.

We used straightforward thermal evaporation deposition to form thin Al films on fused silica slides as surface plasmon resonance (SPR) sensors in the blue visible region. Compared to other studies, we achieved high-quality Al SPR sensors with a low vacuum level at 7 × 10-4 Pa and a low deposition rate between 1.47 and 3.41 nm/s. These Al films have an atomic-level surface roughness. With our recipe, the requirements for deposition conditions are relaxed, and the operation time is reduced remarkably. The experimental sensitivity of the bulk refractive index measurements using 405 nm probing light is as high as 149.9°/RIU. Compared with other studies, our blue visible Al SPR completes the Al SPR working frequency range from deep UV to near-infrared which is much broader than the working range of Au SPR sensors. The cost of Al material is cheap, and the deposition instrument is also economic and operation easy. Considering the compatibility with most of the nanofabrication procedures and stability from the native oxide layer, Al SPR sensors have a huge potential to replace Au SPR sensors as the new golden standard of SPR sensing technology.