Surface Plasmon Resonance Properties Research Articles

Novel Strategy towards Efficiency Enhancement of Flexible Optoelectronic Devices with Engineered M13 Bacteriophage

Plasmonic nanostructures, which exhibit notable localized surface plasmon resonance (LSPR) properties, are a promising approach for improving the efficiency of fiber‐shaped dye‐sensitized solar cells (FDSSCs) and flexible organic light‐emitting diodes (FOLEDs). Herein, novel plasmonic nanostructure is successfully synthesized via the self‐densification of gold nanoparticles (Au NPs) onto a genetically engineered M13 bacteriophage template. The synthesized Au NP‐M13 bio‐nanostructure show extraordinary gap‐plasmon effects and significantly enhanced LSPR properties compared to randomly dispersed Au NPs for both solid‐state FDSSCs (SS‐FDSSCs) and FOLEDs. Briefly, a power conversion efficiency (PCE) increment of 40.7% is recorded for the Au metallic NPs‐anchored M13 bacteriophage (Au NPs‐M13) enhanced SS‐FDSSCs; whereas an external quantum efficiency (EQE) increment of 47.2% is achieved for the Au NPs‐M13 enhanced FOLEDs.

Effect of thermal annealing on the surface plasmon properties of gold and silver nanodisk structures fabricated by electron beam lithography

This study investigates the effect of thermal annealing on the surface plasmon resonance properties of gold and silver nanodisk structures fabricated by electron beam lithography. Despite no significant size change due to a nickel adhesion layer, thermal annealing at 500 °C notably altered surface plasmon resonance properties, especially in gold nanodisks, which showed peak blue-shifts and narrowing, indicating improved crystallinity. We fitted the peak shift by using an electromagnetic field analysis and discussed the changes in the dielectric function. The dielectric function of the simple Drude model was adopted, which was fitted to the values of the Lorentz Drude model in a limited wavelength region. While both silver and gold exhibited increased oscillation strength, only gold nanodisk structures showed a decrease in damping frequency. Increased oscillation strength indicated that these structures should be useful for selective enhancement of the light at specific wavelengths by a very simple heat treatment.

Utilizing agricultural biowaste for food safety: Integrating naturally synthesized silver nanoparticles as antibacterial coating

The growing global population drives increased food demand, impacting the global packaging materials sector, leading to the development of active packaging to enhance food quality, shelf life, and safety. Proper packaging materials, with improved antibacterial and antioxidant barriers, are becoming important in the food sector to reduce food loss and contamination. This study uses Egyptian basil Ocimum basilicum L manufacturing wastes as a biowaste, an agro-industry waste, as a reducing and capping agent to biosynthesize silver nanoparticles (AgNPs). Then, different contents from AgNPs (0.5, 2, 4 wt%) were entrapped into polyurethane nanofiber (PUNFs) to enhance the antimicrobial and antioxidant properties. Gas chromatography/mass spectrometry (GC/MS) was employed to analyze the chemical constituents present in the aqueous peel extract of Ocimum basilicum L. The physicochemical properties of AgNPs before and after entrapped nanofibers were investigated, their antimicrobial and antioxidant properties were evaluated. As a result of the distinctive surface plasmon resonance properties exhibited by Ag (metallic nanoparticles), there are notable peaks observed at 272.5 nm and a prominent peak at 467.3 nm. TEM analyses indicated that the AgNPs were consistently round and uniform, measuring an average of 17.16 ± 1.94 nm in diameter; SEM also confirmed these findings. AgNPs were found to possess their typical crystalline structure, as evidenced by the results of XRD and TEM analyses. The rise in nanofiber diameter is responsible for the escalated AgNP concentration. The presence of AgNPs and Ocimum basilicum L biowaste significantly enhanced the antibacterial and antioxidant properties compared to pure TPU.

Multidimensional Interactive Cascading Nanochips for Detection of Multiple Liver Diseases via Precise Metabolite Profiling.

It is challenging to detect and differentiate multiple diseases with high complexity/similarity from the same organ. Metabolic analysis based on nanomatrix-assisted laser desorption/ionization mass spectrometry (NMALDI-MS) is a promising platform for disease diagnosis, while the enhanced property of its core nanomatrix materials has plenty of room for improvement. Herein, a multidimensional interactive cascade nanochip composed of iron oxide nanoparticles (FeNPs)/MXene/gold nanoparticles (AuNPs), IMG, is reported for serum metabolic profiling to achieve high-throughput detection of multiple liver diseases. MXene serves as a multi-binding site and an electron-hole source for ionization during NMALDI-MS analysis. Introduction of AuNPs with surface plasmon resonance (SPR) properties facilitates surface charge accumulation and rapid energy conversion. FeNPs are integrated into the MXene/Au nanocomposite to sharply reduce the thermal conductivity of the nanochip with negligible heat loss for strong thermally-driven desorption, and construct a multi-interaction proton transport pathway with MXene and AuNPs for strong ionization. Analysis of these enhanced serum fingerprint signals detected from the IMG nanochip through a neural network model results in differentiation of multiple liver diseases via a single pass and revelation of potential metabolic biomarkers. The promising method can rapidly and accurately screen various liver diseases, thus allowing timely treatment of liver diseases.

Size-Dependent Surface Plasmon Resonance of Green Synthesized Gold Nanoparticles Using <i>Mangifera indica</i> Fruit Peel Extract

Gold nanoparticles (AuNPs) have been studied for various applications due to their adjustable surface plasmon resonance (SPR) properties and facile synthesis. AuNP production has predominantly relied on synthetic chemicals to reduce and stabilize gold precursors. There is an increasing demand for environmentally friendly synthesis methods due to ecological concerns. This work introduced a green synthesis approach using Mangifera indica fruit peel extract. Obtained through maceration of dried fruit peels, this extract served as a reducing agent for gold precursors at 80°C. We obtained varying sizes of AuNPs by manipulating the initial concentration of gold ions: 0.1mM, 0.25mM, and 0.5mM. The UV-vis spectroscopy results confirmed the signature SPR peak for AuNPs around 530 nm, with peak shifts highly dependent on the gold ion concentration. The dynamic light scattering (DLS) measurements revealed hydrodynamic diameters of 89.5 nm, 121.5 nm, and 144.5 nm for the various concentrations. The Fourier transform (FTIR) analysis identified the role of inherent phenols and flavonoids in gold precursor reduction. This study emphasizes the potential of Mangifera indica fruit peel extract as a viable alternative for AuNP synthesis. This study could possibly boost the utilization of gold nanoparticles towards applications in biology and medicine as well as environmental remediation.

A New Synthesis of Copper Nanoparticles and Its Application as a Beta-Hematin Inhibitor

To prevent the development of drug resistance and unwanted side effects, nanomaterials have been studied for their potential to inhibit beta-hematin, an important protein for the survival of malaria parasites. The use of nanomaterials as a medication against parasites and mosquito vectors has recently shown promising drug therapeutic strategies. One of the newest areas of interest in nanotechnology and nanoscience is the environmentally friendly production of nanoparticles. Green synthesis to produce metal nanoparticles is the most important strategy to overcome the possible dangers of toxic chemicals for a safe and harmless environment. For this study, copper nanoparticles (CuNPs) were synthesized using Iraqi basil leaf extract, demonstrating its novelty in nanosciences. The formation of CuNPs can be seen visually as a color shift from green to brownish. UV-vis absorption spectra, Fourier transform infrared (FTIR), X-ray diffraction (XRD), energy dispersive X-ray (EDX), and scanning electron microscopy (SEM) were used to characterize the synthesized nanoparticles. The surface plasmon resonance property (SPR) of CuNPs is revealed by UV-vis analysis, which shows a distinctive absorption peak at 420–430 nm, whereas SEM reveals the spherical shape of CuNPs with sizes ranging from 30 to 50 nm.

Dual-plasmonic Au@Cu7S4 yolk@shell nanocrystals for photocatalytic hydrogen production across visible to near infrared spectral region

Near infrared energy remains untapped toward the maneuvering of entire solar spectrum harvesting for fulfilling the nuts and bolts of solar hydrogen production. We report the use of Au@Cu7S4 yolk@shell nanocrystals as dual-plasmonic photocatalysts to achieve remarkable hydrogen production under visible and near infrared illumination. Ultrafast spectroscopic data reveal the prevalence of long-lived charge separation states for Au@Cu7S4 under both visible and near infrared excitation. Combined with the advantageous features of yolk@shell nanostructures, Au@Cu7S4 achieves a peak quantum yield of 9.4% at 500 nm and a record-breaking quantum yield of 7.3% at 2200 nm for hydrogen production in the absence of additional co-catalysts. The design of a sustainable visible- and near infrared-responsive photocatalytic system is expected to inspire further widespread applications in solar fuel generation. In this work, the feasibility of exploiting the localized surface plasmon resonance property of self-doped, nonstoichiometric semiconductor nanocrystals for the realization of wide-spectrum-driven photocatalysis is highlighted.

Thermal-effect dominated plasmonic catalysis on silver nanoislands.

Plasmonic metal nanostructures with the intrinsic property of localized surface plasmon resonance can effectively promote energy conversion in many applications such as photocatalysis, photothermal therapy, seawater desalinization, etc. It is known that not only are plasmonically excited hot electrons generated from metal nanostructures under light irradiation, which can effectively trigger chemical reactions, but also plasmonically induced heating simultaneously occurs. Although plasmonic catalysis has been widely explored in recent years, the underlying mechanisms for distinguishing the contribution of hot electrons from thermal effects are not fully understood. Here, a simple and efficient self-assembly system using silver nanoislands as plasmonic substrates is designed to investigate the photo-induced azo coupling reaction of nitro- and amino-groups at various temperatures. In the experiments, surface-enhanced Raman spectroscopy is employed to monitor the time and temperature dependence of plasmon-induced catalytic reactions. It was found that a combination of hot electrons and thermal effects contribute to the reactivity. The thermal effects play the dominant role in the plasmon-induced azo coupling reaction of nitro-groups, which suggests that the localized temperature must be considered in the development of photonic applications based on plasmonic nanomaterials.

Advances in Gold Nanoparticles: Synthesis, Functionalization Strategies, and Theranostic Applications in Cancer.

Cancer is among the leading causes of mortality and morbidity in the world. Metallic nanoparticles, especially gold nanoparticles (AuNPs) have emerged to be attractive systems to circumvent the associated adverse effects. By the virtue of their unique properties of tunable size, shape, composition, optical properties, biocompatibility, minimal toxicity, multivalency, fluorescence-luminescence property and surface plasmon resonance; AuNPs have the potential to be used as drug delivery systems. It is vital to ensure that the drug reaches the target site of action for selective kill of cancer cells without harm to healthy cells. These AuNPs can be easily functionalized with a wide array of ligands like peptides, oligonucleotides, polymers, carbohydrates for active targeting to ensure site specific delivery and reduced systemic effects. AuNPs have been in-vestigated as carriers for gene delivery, drug delivery with or without photothermal therapy, in diagnosis based on radiation or spectroscopy. They have emerged as attractive theranostic approach in the overall management of cancer with superior benefit to risk features. In this review, we have discussed synthesis of different AuNPs (nanorods, spherical nanoparticles, and hollow AuNPs), their functionalization strategies and their applications in biomedical domain. Various research studies and clinical trials on application of AuNPs in diagnosis and therapeutics are highlighted.

Plasmonic silver and gold nanoparticles: shape- and structure-modulated plasmonic functionality for point-of-caring sensing, bio-imaging and medical therapy.

Silver and gold nanoparticles have found extensive biomedical applications due to their strong localized surface plasmon resonance (LSPR) and intriguing plasmonic properties. This review article focuses on the correlation among particle geometry, plasmon properties and biomedical applications. It discusses how particle shape and size are tailored via controllable synthetic approaches, and how plasmonic properties are tuned by particle shape and size, which are embodied by nanospheres, nanorods, nanocubes, nanocages, nanostars and core-shell composites. This article summarizes the design strategies for the use of silver and gold nanoparticles in plasmon-enhanced fluorescence, surface-enhanced Raman scattering (SERS), electroluminescence, and photoelectrochemistry. It especially discusses how to use plasmonic nanoparticles to construct optical probes including colorimetric, SERS and plasmonic fluorescence probes (labels/reporters). It also demonstrates the employment of Ag and Au nanoparticles in polymer- and paper-based microfluidic devices for point-of-care testing (POCT). In addition, this article highlights how to utilize plasmonic nanoparticles for in vitro and in vivo bio-imaging based on SERS, fluorescence, photoacoustic and dark-field models. Finally, this article shows perspectives in plasmon-enhanced photothermal and photodynamic therapy.

Evaluations of ethylene glycol and polyethylene glycol aqueous solutions using a hybrid sensor of surface plasmon resonance and quartz crystal microbalance

A hybrid sensor based on surface plasmon resonance (SPR) and quartz crystal microbalance (QCM) was prepared. One of the electrodes of the QCM sensor had a grating structure to enable SPR excitation. The SPR property was investigated through the transmission of the visible-light spectrum. The theoretical calculation showed that the experimental values almost corresponded to the theoretical ones; this suggests that the transmitted light dips were due to SPR. In order to investigate the usefulness of this hybrid sensor, the characteristics of SPR and the oscillation frequency drops of QCM (ΔF QCM) were investigated for aqueous solutions of ethylene glycol and polyethylene glycols with various degrees of polymerization. The position and slope of the SPR dip wavelength and the ΔF QCM curves depended on the degree of polymerization, suggesting that the sensor can be used to evaluate a solution property and/or discriminate a solute material.

Nanotip-Induced Electric Field for Hydrogen Catalysis.

Local electric field induced by the lightning-rod effect attracts great attention for regulating the local microenvironment and electronic properties of active sites. Nevertheless, local electric-field-assisted applications are mainly limited to metals with strong surface plasmonic resonance properties (e.g., Au, Ag, and Cu). Herein, we fabricate RuCu snow-like nanosheets (SNSs) with high-curvature nanotips for enhancing the hydrogen oxidation reaction (HOR) and hydrogen evolution reaction (HER). Theoretical simulations show that RuCu SNSs can induce a strong local electric field around the sharp nanotips, which favors the accumulation of OH- for HOR and H+ for HER. Cu incorporation can modulate the binding strength of OH* and H*, leading to significantly enhanced HOR and HER performance. Impressively, the mass activity of RuCu SNSs for alkaline HOR is 31.3 times higher than that of RuCu nanocrystals without sharp tips. Besides, the required overpotential for reaching 10 mA cm-2 during HER over RuCu SNSs is 14.0 mV.

Design and fabrication of Zn@ZnO@Ag chip for Raman scattering analysis of norfloxacin in liquid milk, fish and animal feeds.

A novel and easy-to-prepare plasmonic nanoparticles doped semiconductor substrate-Zn@ZnO@Ag chip with ultra-high surface-enhanced Raman scattering (SERS) activity was fabricated for label-free, rapid and sensitive analysis of norfloxacin. The Zn@ZnO array was synthesized by surface oxidation at low temperature, followed by in-situ reduction to form leaf-like AgNPs on Zn@ZnO array without extra reducing agent, thus fabricating a Zn@ZnO@Ag chip. The ultra-high SERS activity is attributed to the synergistic effect of semiconductor characteristics of ZnO and surface plasmon resonance properties of leaf-like AgNPs. The possible enhancement mechanism was verified by density functional theory simulations. The proposed SERS method showed a wide linear range (3.0-500.0μg/L) and low limit of detection (0.8μg/L) for norfloxacin analysis. High sensitivity, good selectivity and acceptable recoveries (82.7-113.6%) in real sample analysis were obtained. This study offers a promising SERS chip-based platform for norfloxacin detection in the field.

One-pot synthesis of multipod Au-Cu nanocrystals with tunable branching for efficient photothermal treatment against multidrug-resistant bacteria

The plasmonic metal nanoparticle endowed with attractive localized surface plasmon resonance (LSPR) property is promising in the biomedical application. Herein, branched AuCu nanoalloys have been fabricated in one-pot, the morphology of which could be modified by altering the amine capping agent and thus obtaining monopods, tetrapods and pentapods nanostructure. Corresponding to nanoparticles with variable shape in aqueous solution, LPSR peaks were observed in the UV–vis extinction spectra, covering the visible region around 530 nm and the extended near-infrared (NIR) region at 780 nm and more than 1100 nm for AuCu nano-tetrapods and nano-pentapods respectively. The effective photothermal conversion is detected for the as-mentioned three nanostructures, among which AuCu nano-tetrapods and AuCu nano-pentapods achieved superb photothermal efficiency value under the 808-nm and 1064-nm laser irradiations, respectively, in consistence with their strong LPSR absorption wavelength around 780 nm and 1100 nm. Arising from such photothermal properties, the AuCu nano-tetrapods exhibited excellent antibacterial efficiency with minimal inhibitory concentration (MIC) of 29.3 μg mL−1 and facilitated to inhibit a wide range of multidrug-resistant bacteria.

A microfluidic platform for minute-scale synthesizing Au@Ag nanocubes

Noble metal nanoparticles are enduring primarily because of their unique Localized Surface Plasmon Resonance (LSPR) properties, which make them exciting for medical testing, biosensing, and other applications. The LSPR properties of nanoparticles with different shapes and different structures vary. The sharp edges of the cubic structure enable stronger LSPR performance making it more versatile for diverse applications. However, the fast and stable controlled synthesis of cubes, an anisotropic nanoparticle, has been an obstacle for researchers. Microfluidics has a reaction space that matches the scale of the nanoparticles, and the efficient heat and mass transfer capability in the tiny confined space ensures that the synthesis reaction proceeds more efficiently and reliably. Herein, we designed a microfluidic platform for the controlled synthesis of Au@Ag nanocubes, which can synthesize core-shell nanocubes of uniform shape and size in 15 min. Moreover, both Raman probe methylene blue and antibiotic sulfadiazine were detected using this material as a substrate for SERS detection, obtaining satisfactory results (10−10 M and 10−7 M, separately).

Design of Silica@Au Hybrid Nanostars for Enhanced SERS and Photothermal Effect.

Core-shell nanostructures of silicon oxide@noble metal have drawn a lot of interest due to their distinctive characteristics and minimal toxicity with remarkable biocompatibility. Due to the unique property of localized surface plasmon resonance (LSPR), plasmonic nanoparticles are being used as surface-enhanced Raman scattering (SERS) based detection of pollutants and photothermal (PT) agents in cancer therapy. Herein, we demonstrate the synthesis of multifunctional silica core - Au nanostars shell (SiO2 @Au NSs) nanostructures using surfactant free aqueous phase method. The SERS performance of the as-synthesized anisotropic core-shell NSs was examined using Rhodamine B (RhB) dye as a Raman probe and resulted in strong enhancement factor of 1.37×106 . Furthermore, SiO2 @Au NSs were also employed for PT killing of breast cancer cells and they exhibited a concentration-dependent increase in the photothermal effect. The SiO2 @Au NSs show remarkable photothermal conversion efficiency of up to 72 % which is unprecedented. As an outcome, our synthesized NIR active SiO2 @Au NSs are of pivotal importance to have their dual applications in SERS enhancement and PT effect.

Ultrasensitive Monitoring of Cyanide Concentrations in Water Using a Aucore-Agshell Hybrid-Coating-Based Fiber Optical Sensor.

Cyanides, which are extremely toxic chemicals that are rapidly absorbed into the human body and interact with cytochrome oxidase, strongly inhibit cellular respiration to body death with convulsions. Cyanide ions that exist in many forms in nature such as those found in apricot kernels, cassava roots, and bamboo shoots as cyanogenic glycosides are inevitably used in various industries, including gold and silver mining as well as in dyes and plastic industries. In this study, for the sake of developing ultrahigh-sensitive sensors for cyanide monitoring in a simple manner, we chemically synthesize Aucore-Agshell hybrid nanomaterials of different core/shell thicknesses for colorimetric sensors and fiber optical sensors. Their sensing principle relies on the formation of the Ag/Au cyanocomplex upon cyanide injection. The generated metal cyanocomplex induced changes in refractive indices, causing changes in properties of localized surface plasmon resonance (LSPR), i.e., optical absorbance change for the colorimetric sensors. For fiber optical sensors, the hybrid metal nanoparticles were immobilized on the fiber core surface and the metal cyanocomplex formation induced changes in the fiber cladding refractive index, enabling quantitative cyanide detection with ultrahigh sensitivity. The LSPR-based colorimetric sensor provided the lowest detectable cyanide concentration of 5 × 10-6 M, whereas the value for the fiber-based sensor was 8 × 10-11 M.

Localized surface plasmon resonance properties dependence of green-synthesized Fe3O4/Ag composite nanoparticles on Ag concentration and an electric field for biosensor application

The use of green-synthesized Fe3O4/Ag composites nanoparticles (NPs) on the surface plasmon resonance (SPR) system induced by the electric field generates the effect of electrooptic-localized surface plasmon resonance (EO-LSPR). EO-LSPR is the promising method to increase dispersibility, generate plasmons, bind to biomolecular targets, modify the refractive index, and increase the SPR signal. Green synthesis of Fe3O4/Ag NPs has several advantages, including being environmentally friendly, cost-effective, and sustainable. This research successfully investigated the EO-LSPR properties of green-synthesized Fe3O4/Ag NPs with various Ag concentrations. Green synthesis of Fe3O4/Ag composites NPs was prepared utilizing Moringa oleifera by an aqueous solution method. The EO-LSPR phenomenon was investigated by applying various voltages in the Kretschmann configuration with a layer arrangement of a prism/Au thin film/NPs/air with a wavelength of 632.8 nm. Transmission electron microscope results show that the average size of Fe3O4/Ag particles is around 16.72 ± 7.30 nm. The scanning electron microscopy-energy dispersive x-ray results showed that Ag was distributed on the surface of Fe3O4. The addition of Ag concentration decreased the saturation magnetization while the coercivity field increased. The SPR angle of the prism/Au thin film/air layer structures is 44.66°. After depositing with Fe3O4/Ag with an Ag concentration of 60 millimolar, the LSPR angle shifted by 0.98°. Under an electric field, the LSPR angle shifted to 1.00°, 1.17°, and 1.22° of 2 volts, 4 volts, and 6 volts, respectively. The results show that applying the electric field induces the LSPR angle of Fe3O4/Ag NPs to shift to a larger angle. Applying an electric field causes a change in the material's refractive index. The greater the applied electric field, the more significant the LSPR angle shifts. The significant shifts in the LSPR angle due to the application of an electric field indicate that the EO-LSPR system using green-synthesized Fe3O4/Ag composites NPs could be a promising alternative to increase the performance of SPR biosensors in the future.

Plasmonic CuS 2D nanosheets through biologically and environmentally benign template free one-pot synthesis

Our research unveils a novel and eco-friendly technique for the synthesis of emerging two-dimensional Copper Sulfide (CuS) nanosheets through the sulfidation of surface-modified Cu NPs. These fabricated CuS nanosheets exhibit captivating properties such as fluorescence and surface plasmon resonance (SPR) within the near-infrared (NIR) spectrum, rendering them as remarkable candidates for transformative applications in bioimaging and medical sensing.The structural and optical characterization of the material were carried out, and the morphological characterization using SEM and HRTEM shows the formation of 2D CuS as exfoliated long sheets. The investigation projects a simple and cost-effective method to produce 2D Copper Sulfide (CuS) nanosheets. It is formed through a two-step process, including the synthesis of Cu NPs, and transformation of these colloidal Cu NPs into CuS nanosheets through sulfidation. It is found that the concentrations of sulfur and the surface modifying agents like curcumin and ascorbic acid influence nucleation and promote 2D growth of the nanosheets. The effect of sulfur concentration, pH, and surface modifying agents on SPR properties of the Cu NPs were investigated, and the results are presented here. Additionally, our findings indicate that both seed-mediated syntheses and ligand-assisted surface modification leads to the growth of these CuS nanosheets. The cellular studies show that sulfidation reduces the cellular cytotoxicity of Cu NPs. The sample also exhibits excellent stability and biocompatibility, and it is proved to be a promising candidate for photocatalytic, sensing, and biomedical applications, and hence emerges as a multifunctional 2D material.

Effect of electric field on localized surface plasmon resonance properties of Fe3O4/Ag composite nanoparticles

The effect of an electric field on the localized surface plasmon resonance named LSPR properties of Fe3O4/Ag composite nanoparticles was successfully observed. The co-precipitation method was utilized to synthesize Fe3O4/Ag composite nanoparticles, which were deposited on the surface of Au thin film-coated BK7 hemispherical prisms. The light source used in this research was a He-Ne laser beam with a wavelength of 632.8 nm in the Kretschmann array, consisting of a four-layer material of a prism, Au thin film, Fe3O4/Ag composite nanoparticles, and an air medium. A prominent resonance improvement in electro-optic activity was observed at the plasmon resonance frequency. To observe the effect of the applied electric field on the changes in the SPR properties, electric fields with voltage changes of 0, 2, 4, and 6 volts were applied to a prism/Au thin film/air layer structure and a prism/Au thin film/Fe3O4/Ag composite NPs/air layer structure. The SPR angle of the prism/Au thin film/air layer structure was 45.51º. Under an electric field, the SPR angles shifted by 0.10º, 0.17º, and 0.22º, respectively. In addition, the minimum reflectance increased from 0.05 to 0.09, 0.13, and 0.15, respectively. The LSPR angle of the prism/Au thin film/Fe3O4/Ag composite NPs/air layer structure was 46.11º. Under the electric field, the LSPR angles shifted by 0.03º, 0.06º, and 0.08º, respectively. In addition, the minimum reflectance also increased from 0.06 to 0.09, 0.11, and 0.13, respectively. The results demonstrate that the application of an electric field increases the SPR angle and minimum reflectance. As the electric field increases, the refractive index and the dielectric properties of the environment surrounding the nanoparticles, causing the LSPR angle and minimum reflectance to increase. The significant change in the LSPR angle and minimum reflectance due to the application of the electric field indicates that it is possible to use the EO-LSPR system to optimize the performance of the SPR biosensor for future applications.