Surface Plasmon Resonance Detection Research Articles

Experimental Study on SPR Array Sensing Chip Integrated with Microvalves.

This paper discusses a microfluidic system designed for surface plasmon resonance (SPR) sensing, incorporating integrated microvalves. This system is built from a layered structure of polydimethylsiloxane (PDMS) and polymethylmethacrylate (PMMA). The functionality of the microvalves is verified through a conductance method involving electrodes positioned at the microfluidic channels' inlets and outlets. These microvalves can fully close at a control pressure of 0.3 MPa, with their operation depending on the duration of the applied pressure. The study further explores the coordinated operation of multiple microvalves to regulate the sequential flow of samples and reagents in the system. In SPR detection experiments, the microfluidic system is integrated with an SPR array sensing system to control the injection of NaCl solutions via the microvalves, and the observation of phase change curves in different chip regions are observed. The findings validate the microvalves' dependability and suitability for use in SPR array sensing.

SPR and Double Resonance LPG Biosensors for Helicobacter pylori BabA Antigen Detection.

Given the medical and social significance of Helicobacter pylori infection, timely and reliable diagnosis of the disease is required. The traditional invasive and non-invasive conventional diagnostic techniques have several limitations. Recently, opportunities for new diagnostic methods have appeared based on the recent advance in the study of H. pylori outer membrane proteins and their identified receptors. In the present study we assess the way in which outer membrane protein-cell receptor reactions are applicable in establishing a reliable diagnosis. Herein, as well as in other previous studies of ours, we explore the reliability of the binding reaction between the best characterized H. pylori adhesin BabA and its receptor, the blood antigen Leb. For the purpose we developed surface plasmon resonance (SPR) and double resonance long period grating (DR LPG) biosensors based on the BabA-Leb binding reaction for diagnosing H. pylori infection. In SPR detection, the sensitivity was estimated at 3000 CFU/mL-a much higher sensitivity than that of the RUT test. The DR LPG biosensor proved to be superior in terms of accuracy and sensitivity-concentrations as low as 102 CFU/mL were detected.

2D MOF-enhanced SPR detector based on tunable supramolecular probes for direct and sensitive detection of DOX in serum.

Therapeutic drug monitoring of doxorubicin (DOX) is important to studypharmacokinetics in patients undergoing chemotherapy for reduction ofside effects and improve patient survival by rationally controlling the dose of DOX. A fast and ultra-sensitive surface plasmon resonance (SPR) detector without sample pre-handling was developed for DOX monitoring. First, the two-dimensional metal-organic framework was modified on the Au film to enhance SPR, and then, the supramolecular probes with tunable cavity structure were self-assembled at the sensing interface for direct detection of DOX through specific host-guest interactions with a low detection limit of 60.24pM. The precise monitoring of DOX in serum proved the possibility of clinical application with recoveries in the range 102.86-109.47%. The mechanisms of host-guest interactions between supramolecular and small-molecule drugs were explored in depth through first-principles calculations combined with SPR experiments. The study paves the way for designing facile and sensitive detectors and provides theoretical support and a new methodology for the specific detection of small molecules through calixarene cavity modulation.

Green Synthesis of Magnetite Nanoparticles Using <i>Moringa oleifera</i> and their Electro-Optic Surface Plasmon Resonance Properties

The application of an external electric field to the surface plasmon resonance (SPR) system of green-synthesized magnetite (Fe3O4) nanoparticles (MNPs) is very promising for increasing the SPR detection signal. Electro-optic surface plasmon resonance (EOSPR) behavior of MNPs has been successfully carried out. The EOSPR system was investigated using the Kretschmann configuration with the prism/Au thin film/MNPs/air layer arrangement and applying an electric voltage of 0 V, 2 V, 4 V, and 6 V. In this study, we synthesized MNPs using the green synthesis approach from moringa oleifera extract. The benefits of green synthesis include being safe, affordable, clean, and ecologically friendly processes. X-ray diffraction results obtained crystal size of the MNPs is about 9.2 nm with inverse spinel face-centered cubic crystal structure. Fourier transforms infrared characterization showed the presence of Fe-O bonds at wave numbers 569 cm-1 and 629 cm-1, indicating that MNPs were successfully formed. The saturation magnetization of the samples is 55.3 emu/g. The SPR angle of the SPR system Prism/Au thin film/air without the addition of MNPs is 44.66°. After being deposited by MNPs and induced by a voltage of 0 V, 2 V, 4 V, and 6 V, the SPR angles changed to 44.87°, 44.90°, 44.95° and 45.12°. The addition of MNPs and an external electric field causes the SPR angle to increase. The results of this study can provide new insights into the development of optical devices that can be manipulated electrically and have the potential for future biosensor applications.

Biofabrication of silver nanoparticles using Uncaria tomentosa L.: Insight into characterization, antibacterial activities combined with antibiotics, and effect on Triticum aestivum germination

Abstract Herein, we used the aqueous extract of Uncaria tomentosa L. barks (Cat’s claw bark [CCb]) for the biofabrication of silver nanoparticles (CCb-Ag-NPs). The effects of different parameters (Uncaria tomentosa L. aqueous extract, silver nitrate [AgNO3] ratio, temperature, and pH) on the formation of the nanoparticles were investigated using UV scan as a preliminary tool for the detection of surface plasmon resonance of CCb-Ag-NPs. The optimal ratio was 1:7 (Uncaria tomentosa L. extract: 1 mM AgNO3 solution). Fourier-transform infrared spectroscopy revealed the functional groups of both CCb extract and the CCb-Ag-NPs, whose dispersion and quasispherical morphologies were characterized using scanning electron microscopy and transmission electron microscopy. Particle sizes ranged from 19.2 to 38.5 nm. The zeta potential of CCb-Ag-NPs was −34.44 mV. According to energy-dispersive X-ray analysis, the CCb-Ag-NPs contained 28.87% silver. The formation of Ag-NPs was also confirmed by X-ray diffraction pattern analysis. Pristine CCb-Ag-NPs showed antibacterial activity against three pathogenic bacterial strains: Escherichia coli (ATCC 25922), E. coli (ATCC 8739), and Pseudomonas aeruginosa (ATCC 90274). Antibacterial activity increased significantly after loading CCb-Ag-NPs on antibiotic discs containing meropenem and cefoxitin. Low concentrations of CCb-Ag-NPs also enhanced the germination percentage, coleoptile length, and radical root length of Triticum aestivum.

An H-Shaped Exposed Core Surface Plasmon Resonance Sensor and Detection of Cancer Cells

An H-Shaped Exposed Core Surface Plasmon Resonance Sensor and Detection of Cancer Cells

Abstract A044: Screening and characterization of CD38 chimeric antigen receptors for the development of natural killer cell-based therapies

Abstract Background: CD38 is a transmembrane protein that is often overexpressed in multiple myeloma (MM) and other hematologic cancers. The success of anti-CD38 monoclonal antibodies, like daratumumab and isatuximab, in the treatment of MM supports the potential of CD38-targeting therapy candidates in development, including chimeric antigen receptor (CAR) engineered natural killer (NK) cells. Because CD38 is expressed on normal hematopoietic cells and other tissues, it is important to assess the affinity and epitope-specificity of the CD38-targeting moiety to limit potential on-target/off-tumor toxicities. To determine how different biophysical characteristics impact CAR activity, we identified a diverse panel of CD38-specific antibodies, which were shown to display a wide range of affinities and epitopes towards CD38 and converted these clones into CARs to evaluate their expression and target-specific and non-specific activation in a high-throughput (HTP) CD38-knockout (CD38 KO) Jurkat screen. Methods: Antibodies against CD38 were identified through hybridoma screening. Humanized mice were immunized with the extracellular domain of CD38, and lymphocytes from lymph nodes were fused with SP2/0 cells to generate hybridoma cells. Supernatants from single cell sorted hybridoma clones were screened against CD38+ and CD38 KO Jurkat cells and were assessed for affinity and epitope via surface plasmon resonance detection with the Carterra LSA. 96 unique clones were converted into CARs and transduced into CD38 KO Jurkat cells. CAR-expressing Jurkat cells were assayed for CAR expression and activation (via CD69 expression) when cultured overnight in the presence or absence of MM.1R target cells. Seven CARs were selected for additional characterization in primary NK cells. NK cells from healthy donors were expanded on our proprietary NKSTIM cell line, knocked out for CD38 using a CRISPR-Cas system, and transduced with CD38 CAR constructs. CD38 CAR NK-mediated cytotoxicity against MM.1S target cells was assessed by IncuCyte® S3 live cell analysis system. Results: Hybridoma screening identified many unique CD38-specific antibodies, displaying a wide range of affinities and epitopes towards CD38. Despite these biophysical differences, many of these antibodies, when converted to CARs, confer target-specific activity. Multiple epitopes on CD38 may be targeted and even low affinity antibodies were sufficient for target-specific CAR activation. Furthermore, the seven selected CAR candidates that were expressed in CD38 KO donor NK cells displayed potent in vitro target cell killing against MM.1S target cells. Conclusions: In summary, we have identified and characterized a range of CD38-specific antibodies. When converted into CARs, these targeting moieties mediate target-specific activation, despite differences in CD38 epitope and in affinity, demonstrating the utility of HTP CAR screening. Moreover, expression of the top seven CAR candidates in CD38 KO NK cells resulted in potent target cell killing, supporting further pre-clinical evaluation in relevant models. Citation Format: Emily N Kang, Jacinda T Chen, Bing Li, Kate Jamboretz, Nitin Patel, Daniel Bedinger, Kyle T Pratt, Jessica Hsieh, Luxuan TE Buren, Chao Guo, Ivan Chan, James B Trager, Sasha Lazetic. Screening and characterization of CD38 chimeric antigen receptors for the development of natural killer cell-based therapies [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Tumor Immunology and Immunotherapy; 2023 Oct 1-4; Toronto, Ontario, Canada. Philadelphia (PA): AACR; Cancer Immunol Res 2023;11(12 Suppl):Abstract nr A044.

E. coli O157:H7 Detection Using Surface Plasmon Resonance Based Biosensor

The detection of foodborne pathogenic bacteria remains a significant challenge, and the need for fast and sensitive detection methods is becoming increasingly important. Escherichia coli is a prevalent bacteria associated with foodborne illness, and this study aimed to evaluate the ability of a surface plasmon resonance (SPR) based biosensor to detect E. coli O157:H7 at low levels in pure culture and artificially contaminated bay leaves (Laurus nobilis) using different injection methods. To develop a biological sensing surface, the sensor surface was functionalized with 3-aminopropyltriethoxysilane (APTES), and polyclonal antibodies were immobilized on the surface for bacteria detection. Bacterial attachment to the antibodies resulted in a change in resonance angle. The biosensor was able to discriminate between cellular concentrations of 103 to 107 CFU/mL and showed potential in detecting different pathogens in various food samples. Before the SPR detection, the sample preparation step was optimized to ensure complex food matrices were suitable for SPR analysis. The results suggest that the SPR based biosensor is a promising tool for the rapid detection of foodborne pathogens in complex food matrices.

Novel surface plasmon resonance detector for the detection of various alcohols with ultra-high sensitivity

Novel surface plasmon resonance detector for the detection of various alcohols with ultra-high sensitivity

Biosensors for the Detection of Food Allergens.

Biosensors enable fast and specific detection of various molecules, including allergens. Surface plasmon resonance (SPR) aptasensors combine the capabilities of SPR detection, i.e., sensitive, fast, label-free, and real-time monitoring with the specificity and stability of aptamers for the biorecognition of various ligands. Compared to other toxic compounds in food, allergens pose specific analytical challenges. Among allergens, lysozyme, also named Gal d 4, is a food additive used in cheese, wine, beer, sausages, etc., to control bacterial activity. In this chapter, we describe an SPR aptasensor that is applicable for lysozyme analysis in wines. Besides detecting residual allergen amounts, the aptasensor can be used to monitor the interaction of lysozyme with phenolic compounds in wine.

Application of the Nicoya OpenSPR to Studies of Biomolecular Binding: A Review of the Literature from 2016 to 2022

The Nicoya OpenSPR is a benchtop surface plasmon resonance (SPR) instrument. As with other optical biosensor instruments, it is suitable for the label-free interaction analysis of a diverse set of biomolecules, including proteins, peptides, antibodies, nucleic acids, lipids, viruses, and hormones/cytokines. Supported assays include affinity/kinetics characterization, concentration analysis, yes/no assessment of binding, competition studies, and epitope mapping. OpenSPR exploits localized SPR detection in a benchtop platform and can be connected with an autosampler (XT) to perform automated analysis over an extended time period. In this review article, we provide a comprehensive survey of the 200 peer-reviewed papers published between 2016 and 2022 that use the OpenSPR platform. We highlight the range of biomolecular analytes and interactions that have been investigated using the platform, provide an overview on the most common applications for the instrument, and point out some representative research that highlights the flexibility and utility of the instrument.

A Fully Integrated Miniaturized Optical Biosensor for Fast and Multiplexing Plasmonic Detection of High- and Low-Molecular-Weight Analytes.

Optical biosensors based on plasmonic sensing schemes combine high sensitivity and selectivity with label-free detection. However, the use of bulky optical components is still hampering the possibility of obtaining miniaturized systems required for analysis in real settings. Here, a fully miniaturized optical biosensor prototype based on plasmonic detection is demonstrated, which enables fast and multiplex sensing of analytes with high- and low molecular weight (80 000 and 582 Da) as quality and safety parameters for milk: a protein (lactoferrin) and an antibiotic (streptomycin). The optical sensor is based on the smart integration of: i) miniaturized organic optoelectronic devices used as light-emitting and light-sensing elements and ii) a functionalized nanostructured plasmonic grating for highly sensitive and specific localized surface plasmon resonance (SPR) detection. The sensor provides quantitative and linear response reaching a limit of detection of 10-4 refractive index units once it is calibrated by standard solutions. Analyte-specific and rapid (15 min long) immunoassay-based detection is demonstrated for both targets. By using a custom algorithm based on principal-component analysis, a linear dose-response curve is constructed which correlates with a limit of detection (LOD) as low as 3.7µg mL-1 for lactoferrin, thus assessing that the miniaturized optical biosensor is well-aligned with the chosen reference benchtop SPR method.

A Numerical Study of Different Metal and Prism Choices in the Surface Plasmon Resonance Biosensor Chip for Human Blood Group Identification.

Optimized design of Surface plasmon resonance (SPR) based biosensor in terms of different metal choices and prisms are presented to the first time for the high precision detection of human blood group in near infrared wavelength range. The results are well compared with the earlier published gold coated silicon biosensor chip while discussing the pros and cons of various prism/metal choices. In this study buffer layer onto SPR active metal has been deployed to avoid the oxidation problem and contamination issue related with blood samples. Refractive index of blood samples has been considered in theoretical model based on the experimental data. Si prism has been found to be the best choice as a substrate material with combination of Al as a SPR active metal for blood group identification analysis. SPR dip slope (S), detection accuracy (D.A.) and blood group discrimination factor ( δθSPR ) have been studied with respect to different metal choices with their suitability to the next generation biosensor applications.

Sensing Mechanisms of Rough Plasmonic Surfaces for Protein Binding of Surface Plasmon Resonance Detection.

Surface plasmon resonance (SPR) has been utilized in various optical applications, including biosensors. The SPR-based sensor is a gold standard for protein kinetic measurement due to its ultrasensitivity on the plasmonic metal surface. However, a slight change in the surface morphology, such as roughness or pattern, can significantly impact its performance. This study proposes a theoretical framework to explain sensing mechanisms and quantify sensing performance parameters of angular surface plasmon resonance detection for binding kinetic sensing at different levels of surface roughness. The theoretical investigation utilized two models, a protein layer coating on a rough plasmonic surface with and without sidewall coatings. The two models enable us to separate and quantify the enhancement factors due to the localized surface plasmon polaritons at sharp edges of the rough surfaces and the increased surface area for protein binding due to roughness. The Gaussian random surface technique was employed to create rough metal surfaces. Reflectance spectra and quantitative performance parameters were simulated and quantified using rigorous coupled-wave analysis and Monte Carlo simulation. These parameters include sensitivity, plasmonic dip position, intensity contrast, full width at half maximum, plasmonic angle, and figure of merit. Roughness can significantly impact the intensity measurement of binding kinetics, positively or negatively, depending on the roughness levels. Due to the increased scattering loss, a tradeoff between sensitivity and increased roughness leads to a widened plasmonic reflectance dip. Some roughness profiles can give a negative and enhanced sensitivity without broadening the SPR spectra. We also discuss how the improved sensitivity of rough surfaces is predominantly due to the localized surface wave, not the increased density of the binding domain.

Surface Plasmon Resonance Biosensor Chip for Human Blood Groups Identification Assisted with Silver-Chromium-Hafnium Oxide

Chromium (Cr), silver (Ag) and hafnium oxide (HfO2) are used in a surface plasmon resonance (SPR)-based biosensor with an optimized design for measuring blood groups at a wavelength of 633 nm. A buffer layer was placed on the SPR active metal in this investigation to avoid oxidation and contamination of blood samples. A theoretical model based on experimental data considered the refractive index of blood samples. The BK7 prism is the optimum substrate material for blood type identification analysis using a combination of Ag and Cr as an SPR active metal. The sensor’s performance is carefully researched in terms of its angular shift and curve width to predict the design aspects that provide precise blood-group identification. The SPR dip slope, detection accuracy and figure of merit (FOM) have been investigated concerning the subsequent generation of biosensor applications.

Surface plasmon resonance detection of UV irradiation-induced DNA damage and photoenzymatic repair processes through specific interaction between consensus double-stranded DNA and p53 protein.

DNA damage, such as DNA lesions and strand breaks, impairs normal cell functions and failure in the DNA repair process could lead to gene mutation, cell apoptosis and disease occurrence. p53 is a tumor suppressor and DNA-binding protein, and DNA damage might affect their interaction and the subsequent p53 function. Herein, real-time monitoring of DNA damage and repair processes through DNA-p53 protein interaction was performed by surface plasmon resonance (SPR). The target DNA with consecutive pyrimidine nucleobases was first damaged upon UVC (254 nm) irradiation and then photoenzymatically repaired under UVA (365 nm) irradiation. The as-formed double-stranded (ds) DNA between probe DNA and normal, damaged or repaired target DNA was immobilized on the sensor chips, followed by the injection of p53 protein. By measuring the SPR signals under different cases, the DNA damage and repair processes could be conveniently monitored. The SPR signals were inversely proportional to the UVC doses ranging from 0.021 to 1.26 kJ m-2, providing a viable means for the quantification of the DNA damage level. The binding affinity between p53 and the dsDNA formed upon the hybridization of probe DNA and normal, damaged, or photoenzymatically repaired target DNA was estimated. This is the first report on measuring the equilibrium dissociation constant (KD) between the p53 protein and the dsDNA with photodamaged or repaired target sequences. The sensing strategy by SPR thus opens a new avenue for real-time measurement of the DNA damage and the repair processes.

DNA-Directed Protein Anchoring on Oligo/Alkanethiol-Coated Gold Nanoparticles: A Versatile Platform for Biosensing Applications

Herein, we report on a smart biosensing platform that exploits gold nanoparticles (AuNPs) functionalized through ssDNA self-assembled monolayers (SAM) and the DNA-directed immobilization (DDI) of DNA-protein conjugates; a novel, high-sensitivity optical characterization technique based on a miniaturized gel electrophoresis chip integrated with online thermal lens spectrometry (MGEC-TLS), for the high-sensitivity detection of antigen binding events. Specifically, we characterized the physicochemical properties of 20 nm AuNPs covered with mixed SAMs of thiolated single-stranded DNA and bio-repellent molecules, referred to as top-terminated oligo-ethylene glycol (TOEG6), demonstrating high colloidal stability, optimal binder surface density, and proper hybridization capacity. Further, to explore the design in the frame of cancer-associated antigen detection, complementary ssDNA fragments conjugated with a nanobody, called C8, were loaded on the particles and employed to detect the presence of the HER2-ECD antigen in liquid. At variance with conventional surface plasmon resonance detection, MGEC-TLS characterization confirmed the capability of the assay to titrate the HER2-ECD antigen down to concentrations of 440 ng/mL. The high versatility of the directed protein-DNA conjugates immobilization through DNA hybridization on plasmonic scaffolds and coupled with the high sensitivity of the MGEC-TLS detection qualifies the proposed assay as a potential, easily operated biosensing strategy for the fast and label-free detection of disease-relevant antigens.

Surface-enhanced Raman Scattering and Localized Surface Plasmon Resonance Detection of Aldehydes Using 4-ATP Functionalized Ag Nanorods

Formaldehyde, acetaldehyde, and benzaldehyde are well-known carcinogens affecting human health adversely. Thus, there is a need for efficient detection of these aldehydes. This work uses 4-aminothiophenol (4-ATP) functionalized silver nanorods (Ag NRs) to detect these three aldehydes. The detection mode includes localized surface plasmon resonance (LSPR) and surface-enhanced Raman scattering (SERS). The LSPR band of 4-ATP functionalized Ag NRs shows a linear decrease in absorbance with the increase in formaldehyde and acetaldehyde concentrations. A sensitivity of 0.96 and 0.79 ΔA/mM for formaldehyde and acetaldehyde were obtained. In the case of benzaldehyde, a nearly exponential decrease in absorbance with the increase in concentrations was observed. Above 98.4 μM concentration, the absorbance diminishes completely. The LoD for formaldehyde and acetaldehyde detection using LSPR is 33.8 and 24.6 μM, respectively. The SERS studies reveal that the 4-ATP binds to Ag NRs through both –SH and –NH2 groups and facilitates the inter-particle charge transfer process. The appearance of b2 modes of vibration for 4-ATP evidences this charge transfer process. In the presence of aldehydes, the change in the band shape, relative intensities, and band position were observed primarily in b2 modes of vibration, evidencing the modulation in the charge transfer process. These remarkable changes were seen in μM concentration of aldehydes. Therefore, detection of these aldehydes with 4-ATP functionalized Ag NRs using SERS is possible in concentrations as low as ~ 1 μM.

A novel approach for measuring membrane permeability for organic compounds via surface plasmon resonance detection

Well-known methods for measuring permeability of membranes include static or flow diffusion chambers. When studying the effects of organic compounds on plants, the use of such model systems allows to investigate xenobiotic behavior at the cuticular barrier level and obtain an understanding of the initial penetration processes of these substances into plant leaves. However, the use of diffusion chambers has disadvantages, including being time-consuming, requiring sampling, or a sufficiently large membrane area, which cannot be obtained from all types of plants. Therefore, we propose a new method based on surface plasmon resonance imaging (SPRi) to enable rapid membrane permeability evaluation. This study presents the methodology for measuring permeability of isolated cuticles for organic compounds via surface plasmon resonance detection, where the selected model analyte was the widely used pesticide metazachlor. Experiments were performed on the cuticles of Ficus elastica, Citrus pyriformis, and an artificial PES membrane, which is used in passive samplers for the detection of xenobiotics in water and soils. The average permeability for metazachlor was 5.23 × 10−14 m2 s−1 for C. pyriformis, 1.34 × 10−13 m2 s−1 for F. elastica, and 7.74 × 10−12 m2 s−1 for the PES membrane. We confirmed that the combination of a flow-through diffusion cell and real-time optical detection of transposed molecules represents a promising method for determining the permeability of membranes to xenobiotics occurring in the environment. This is necessary for determining a pesticide dosage in agriculture, selecting suitable membranes for passive samplers in analytics, testing membranes for water treatment, or studying material use of impregnated membranes.

Highly sensitive sensing of a magnetic field and temperature based on two open ring channels SPR-PCF.

A surface plasmon resonance (SPR) sensor comprising photonic crystal fiber (PCF) is designed for magnetic field and temperature dual-parameter sensing. In order to make the SPR detection of magnetic field and temperature effectively, the two open ring channels of the proposed sensor are coated with gold and silver layers and filled with magnetic fluid (MF) and Polydimethylsiloxane (PDMS), respectively. The sensor is analyzed by the finite element method and its mode characteristics, structure parameters and sensing performance are investigated. The analysis reveals when the magnetic field is a range of 40-310 Oe and the temperature is a range of 0-60 °C, the maximum magnetic field sensitivity is 308.3 pm/Oe and temperature sensitivity is 6520 pm/°C. Furthermore, temperature and magnetic field do not crosstalk with each other's SPR peak. Its refractive index sensing performance is also investigated, the maximum sensitivity and FOM of the left channel sensing are 16820 nm/RIU and 1605 RIU-1, that of the right channel sensing are 13320 nm/RIU and 2277 RIU-1. Because of its high sensitivity and special sensing performance, the proposed sensor will have potential application in solving the problems of cross-sensitivity and demodulation due to nonlinear changes in sensitivity of dual-parameter sensing.