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Biosensing technologies are essential for advancing healthcare by enabling rapid point-of-care (POC) testing and diagnosis, potentially saving lives. Biosensors, such as Localized Surface Plasmon Resonance (LSPR) sensors with gold nanoparticles (AuNPs), show promise in early disease diagnosis due to their simple structure and high sensitivity. However, their commercialization is limited by high production costs and the need for precise optoelectronic systems. This article proposes an affordable optical detection scheme for LSPR sensors named BioColor. BioColor uses a color CMOS camera to capture images of light passing through the sensor elements, which are plasmonic papers composed of AuNPs. Variations in the refractive index over the sensor's surface cause changes in the color of the transmitted light. This color change can be detected through image processing algorithms and the detection results are visualized on the BioColor mobile app, providing instant automated access to sensing outcomes. [ABSTRACT FROM AUTHOR]

Ethanol plays a crucial role in modern industrial processes and consumer products. Despite its presence in human activity, short and long-term exposure to gaseous ethanol poses risks to health conditions and material damage, making the control of its concentration in the atmosphere of high importance. Ethanol optical sensors based on electromagnetic surface waves (ESWs) are presented, with sensitivity to ethanol vapours being achieved by the inclusion of ethanol-adsorptive zinc oxide (ZnO) layers. The changes in optical properties modulate the resonant conditions of ESWs, enabling the tracking of ethanol concentration in the atmosphere. A comprehensive comparative study of sensor performance is carried out between surface plasmon resonance (SPR) and Bloch surface wave (BSW) based sensors. Sensor efficiency is simulated by transfer matrix method towards optimized figures of merit (FoM). Preliminary results validate ethanol sensitivity of BSW based sensor, showcasing a possible alternative to electromagnetic and plasmonic sensors. [ABSTRACT FROM AUTHOR]

This theoretical study presents a D-shaped photonic crystal fiber (PCF) surface plasmon resonance (SPR) based sensor designed for humidity detection in transformer oil. Humidity refers to the presence of water dissolved or suspended in the oil, which can affect its dielectric properties and, consequently, the efficiency and safety of the transformer's operation, failures in the sealing system and the phenomenon of condensation can be the main sources of this humidity. This sensor leverages the unique properties of the coupling between surface plasmons and fiber guided mode at the Au-PCF interface to enhance the sensitivity to humidity changes in the external environment. The research demonstrated the sensor's efficacy in monitoring humidity levels ranging from 0% to 100% with an average sensitivity of measured at 1106.1 nm/RIU. This high sensitivity indicates a substantial shift in the resonance wavelength corresponding to minor changes in the refractive index caused by varying humidity levels, which is critically important in the context of transformer maintenance and safety. Transformer oil serves as both an insulator and a coolant, and its humidity level is a key parameter influencing the performance and longevity of transformers. Excessive humidity can lead to insulation failure and reduced efficiency and, therefore, the ability to accurately detect and monitor humidity levels in transformer oil can significantly enhance preventive maintenance strategies, reduce downtime, and prevent potential failures, ensuring the reliable operation of electrical power systems. [ABSTRACT FROM AUTHOR]

Using no-core optical fiber (NCF) and conventional single-mode fiber (SMF), this research needs to increase the sensitivity of temperature and relative humidity measurements for radiology device applications. Operating on the Mach-tender Interferometer (MZI) principle, the sensors make use of surface plasmon resonance. Traditional sensing technologies sometimes confront difficulties in reaching high sensitivity and accuracy, especially in demanding environments like radiology facilities. In order to increase the sensitivity of four relative humidity sensors constructed from SMF, TNCF, and SMF, a 2 cm NCF segment was incorporated. To enhance sensitivity, the sensors have been coated with a variety of substances, such as gold nanoparticles (AuNPs), silica nanoparticles (PVN/PVP), and a layer-by-layer technique. The sensor coated with AuNPS exhibited the greatest sensitivity with respect to temperature, attaining 0.486 db/°C. The fiber optic sensors that have been developed exhibit great potential for utilization in biomedical and environmental domains. Experimental tests are carried out to assess the performance of the proposed sensing system, including sensitivity, accuracy, and reaction time. [ABSTRACT FROM AUTHOR]

Ion implantation was employed for the growth of embedded silver nanoparticles (NPs) in amorphous hydrogenated silicon nitride (a-SiNx:H) thin films. Crystalline nanoparticles are found to grow in the as-implanted samples without the requirement of an annealing step. The NPs exhibit absorption due to Localized Surface Plasmon Resonance (LSPR). The LSPR peak position, width and intensity, are found depend on the stoichiometry of a-SiNx:H and the implantation energy. A maximum LSPR red shift from 390 nm to 470 nm was obtained with changes in the composition of the host medium. [ABSTRACT FROM AUTHOR]

This study aims to synthesize bio-silver nanoparticles (bio-AgNPs) using leaf extract of Gandaria (Bouea macrophylla Griff) and to observe their antibacterial and antioxidant properties. Silver nanoparticles were formed immediately after the leaf extract of Gandaria was mixed with silver nitrate solution. The formation of silver nanoparticles was confirmed by the color of the mixture, changing from transparent to yellowish-brown, and quantified by a surface plasmon resonance wavelength of 415 nm from the Ultra Violet-Visible (UV-VIS) spectrum. Moreover, the mean diameter of the particles was found to be 38.1±3.8 nm from dynamic light scattering (DLS) measurements, and the Fourier Transform Infra Red (FTIR) spectrum of the sample indicates the presence of the extract on the surface of the particles. The particle antibacterial activities against gram-negative Escherichia coli and gram-positive Staphylococcus aureus were studied using the disc diffusion method, while the particle antioxidant activities were studied using a 2,2-diphenyl-1-picryl-hydrazyl (DPPH) method. The mean diameter of clear zones of disc diffusion for E.coli was found to be 10.5±0.4 mm and for S. aureus 11.5±0.4 mm, indicating the potency of Gandaria leaf extract silver nanoparticles to be an antibacterial agent. The results from DPPH methods show that the nanoparticles with a concentration of 58.96 nM show an inhibition percentage of 22.45±0.08 %, which indicates the potency of Gandaria leaf extract silver nanoparticles to be an antioxidant agent. [ABSTRACT FROM AUTHOR]

AuNPs (gold nanoparticles) are a type of nanomaterial with a high biocompatibility. The goal of this research is to use the Turkevich method to make AuNPs utilizing HAuCl4.3H2O as a precursor and Na3C6H5O7 as a reduction agent. UV-Vis Spectrophotometer (UV-Vis), Fourier Transform Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), and Transmission Electron Microscopy (TEM) characterization of the resulting AuNPs revealed an excellent band of Surface Plasmon Resonance (SPR) of about 542 nm, high crystallinity, variable shape, and a size range of 20-40 nm. This feature indicates that the AuNPs produced can be used in biomedical applications. Chitosan is an excellent antibacterial biomaterial. Shrimp shells were used to synthesize chitosan nanoparticle (CsNPs) in three stages: deproteination, demineralization, and deacetylation. UV-Vis, FTIR, and XRD techniques were used to characterize the resultant chitosan, and it was discovered to be of good quality. The antibacterial properties of chitosan nanoparticles (CsNPs) and chitosan-AuNPs conjugate (Cs-AuNPs) were investigated using the agar diffusion method. CsNPs and Cs-AuNPs were found to effectively diminish the growth of Escherichia coli bacteria, but not Staphylococcus aureus or Enterococcus faecalis bacteria. The findings of this study will open a better understanding of CsNPs and AuNPs as biomedical materials because of their remarkable qualities. [ABSTRACT FROM AUTHOR]

Copper nanoparticles (CuNPs) play an active role in the field of optics, textiles, electrical conductors, catalytic, biochemical sensors, oxidative capacity, pharmaceuticals and medical as antibacterial or sterilization agents. Copper nanoparticles also show specific physical and chemical properties. The aim of this research is to synthesize copper nanoparticles (CuNPs) with various precursors, surfactant concentrations, and temperatures to determine the performance of copper nanoparticles (CuNPs) in inhibiting microbial growth. To obtain copper nanoparticles (CuNPs), chemical reduction of Cu2+ was used as the synthesis method, using cetyltrimethylammonium bromide (CTAB) as a surfactant and sodium borohydride (NaBH4) as a reduction agent. The copper nanoparticles (CuNPs) were characterized by particle size analyzer (PSA) for particle size; UV-visible spectrophotometer to measure absorption peak and agar method to establish antibacterial activity. The results showed that at a precursor, reducing agent, and surfactant ratio of 1:20:4, the particle size of copper nanoparticles (CuNPs) obtained was 92.03 nm. The synthetized copper nanoparticles (CuNPs) were confirmed by a strong absorption peak at 640 nm representing the Cu surface plasmon resonance. The inhibition zones for antibacterial activity were identified at copper nanoparticles (CuNPs) concentrations of 10,000 ppm and 15,000 ppm for Escherichia coli FNCC 0049 and Staphylococcus aureus FNCC 0047, respectively. [ABSTRACT FROM AUTHOR]

Surface Plasmon Resonance (SPR) has been extensively applied as a sensor because of its high sensitivity, accurate selectivity, label-free and real-time biomolecular interactions. In this work, simulation and experiment have been studied on the concentration measurement of ethanol and glucose solutions by SPR sensors. The sensor design used a Kretschmann configuration consisting of Glass/Cr/Au and was simulated by using Finite Difference Time Domain (FDTD) method. The ethanol and glucose solutions with varied concentrations were injected into the SPR channel, and the resonance angle was monitored. For the glucose concentration measurement, the resonance angle increases (from 71.607° to 74.434°) as the glucose concentration increases (from 0% to 15%) with a sensitivity of about 111.71°/RIU. These experimental results agree with the simulation result, which showed a good linear response for the glucose concentration. However, for the ethanol measurement, an increase in resonance angle to the ethanol concentration is not linear in the higher concentration, which is related to the change in the refractive index. However, the excellent correlation between the experiment and simulation results shows that the SPR sensor has good sensitivity and accuracy. [ABSTRACT FROM AUTHOR]

The unique optical properties of gold nanoparticles (AuNPs) have been employed in various applications including colorimetric sensing, which is based on the changes in the localized surface plasmon resonance (LSPR) upon interaction with target analyte. In this work, laser-assisted reduction method was employed to produce uncapped AuNPs. Femtosecond laser pulses and water molecules interact to produce reactive species capable of reducing gold ions. Transmission electron microscope images confirmed the resulted AuNPs to be spherical with average sizes of 7 nm. The uncapped AuNPs were subsequently employed in the colorimetric sensing of hydrogen peroxide (H2O2). H2O2−induced oxidation has been introduced as an alternative detection approach. The proposed system was responsive to the addition of various concentrations of H2O2 in the presence of iodide ions (I−). The colloidal solution color faded and the LSPR intensity decreased as H2O2 concentration increased, indicating the dissolution of AuNPs. The obtained results offer an insight into alternative oxidation-based H2O2 detection method, which is important in the development of non-aggregation based colorimetric sensing using AuNPs. [ABSTRACT FROM AUTHOR]

Surfactant-free gold nanourchins (GNU) have been synthesized using a conventional wet chemical method. Different concentrations of silver nitrate (AgNO3) were added as direction agents to the anisotropic shape, resulting in the different particle sizes. UV-vis spectrometer and transmission electron microscope (TEM) were used to characterize surface plasmon resonance (SPR) absorption at near-infrared region and to validate the morphology of the resulted nanoparticles, respectively. The more AgNO3 is added, the sharper and longer spikes of nanourchins and the bigger particles were generated. These nanourchins were then utilized as substrate for surface-enhanced Raman spectroscopy (SERS) on the detection of methylene blue (MB), a kind of textile dye that was heavily contaminated environment. In this research, fingerprints for methylene blue dye have been identified. SERS performance of our GNU promising for rapid and trace amount detection of another molecular dye. [ABSTRACT FROM AUTHOR]

Detection of H. pylori in saliva is difficult because of its lower concentration there than in the stomach and the presence in the oral cavity of uncharacterized bacteria similar to H. pylori. Therefore, a detection method of high specificity and sensitivity is required. In this study we report such a method involving Surface Plasmon Resonance (SPR) that provides direct detection based on the binding of H. pylori to the blood protein Leb. [ABSTRACT FROM AUTHOR]

The coherent oscillations of conduction electrons near surface of silver nanoparticles (AgNPs) forms a strong surface plasmon resonances (SPR) in the visible spectrum which strongly correlates with its properties in suspension. The present study explores the use of central composite design (CCD) of response surface methodology (RSM) to optimize the two process parameters (irradiation dose and alginate content) on the radiosynthesis of AgNPs without addition of isopropanol as hydroxyl radical scavenger. The CCD-RSM matrix involved 13 run experiments in which the non-destructive UV-Vis spectroscopy method was applied in determination of optimization responses, i.e. the peak absorbance, peak wavelength (λmax) and full width at half maximum (FWHM) of the SPR band. The results showed that the AgNPs successfully synthesized after gamma ray irradiation without addition of isopropanol. The regression models fitted the quadratic models. All responses were significantly influenced by irradiation dose factor through the synergistic linear relationship and the antagonistic quadratic relationship. While, the insignificant effect of alginate content in this study indicates that alginate only plays as a stabilizing agent. The optimum conditions were obtained desirability value of 0.954 where the irradiation dose and alginate content were at 12.7 kGy and 1.00 % (w/v), respectively. The multiresponse optimization model were correspond well with experimental validation results at 95 % confidence interval. Under the optimum condition, the AgNPs suspension was at concentration of 92.7 ppm from yield ratio of 89.65 %, which had spherical shape with average size of 9.96±6.87 nm, hydrodynamic diameter of 11.36 nm, and polydispersity of 0.13. [ABSTRACT FROM AUTHOR]

The study of ciprofloxacin (CIP) electrochemical sensor on AuNPs modified on boron-doped diamond (BDD) electrode is reported. CIP is type of fluoroquinolone antibiotic that widely used to treat gram-positive and gram-negative bacteria. In this work, an average size of chemically generated AuNPs (271.8 nm) was drop-cased on the surface of BDD electrode to fabricate AuNPs modified BDD electrode for CIP sensor. BDD electrode was used as a support due to its excellent properties such as wide potential window and low background current, in which, this property is important to get high sensitivity of a sensor. An oxidation peak of CIP was detected at 1.16 V vs Ag/AgCl, further used as potential to detect CIP. The result show low limit of detection of 0.19 µM. Analysis in real sample shows a good recovery of 86.98%. [ABSTRACT FROM AUTHOR]

This research aims to demonstrate the preparation of ultrathin (1.5 ÷ 15 nm) gold films with a nanostructured surface using RF diode sputtering and to determine the influence of technological parameters on their morphological and optical properties. The early stages of thin film growth, including nuclei formation, growth of clusters, and islands, dominate the growth of nanostructures. Therefore, our research objective is to verify the possibility of forming Au plasmonic nanostructures by sputtering. The sputtering process parameters such as sputtering power, substrate temperature, deposition time, and gas pressure will be systematically varied to achieve this objective. The obtained nanostructured films will be characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM) and UV-Vis spectroscopy to investigate their surface morphology and optical properties. Furthermore, the influence of the thickness and size of the Au nanostructures on their optical properties, such as localized surface plasmon resonance (LSPR), will be investigated. The results of this investigation can provide valuable insights into the formation mechanism of plasmonic nanostructures by sputtering and can have practical implications in developing novel plasmonic devices for various applications, including sensing, imaging and energy conversion. [ABSTRACT FROM AUTHOR]

To improve the dye laser's laser output properties, (Ag nanoparticles) of various sizes were combined with Rhodamine B dye to get a higher intensity as well as a better fluorescence spectrum. It was changed the energy (500, 600, 700, 800, 900 mJ) and kept the pulse number constant at (400 P) to get various sizes of Ag NPs, where the best concentration (1x10-5 M) of RhB dye was mixed with different sizes of Ag NPs and checked the absorbance by UV-VIS spectroscopy and the fluorescence by the emission spectroscopy, and the plasmonic phenomenon in emission spectra (LIF) of Rhodamine B mixed (14000 a.u), noted that increasing the size of the Ag NPs lowers the threshold to a certain limit. [ABSTRACT FROM AUTHOR]

This work presents a novel feasible approach to improve the performance of refractive index sensing that based on local surface plasmon resonance by providing a configuration allowed repeating the resonance event. This repetition has led to double the plasmon response at the resonance condition, and prove that the refractive index sensing was significantly affected by the number of times of local surface plasmon resonance occurs. Optical fiber has been employed as a platform to repeat the plasmonic events resonance. The results confirmed that there is an improvement in the local surface plasmon curve characteristics, the full width at half maximum (FWHM) of the signal has been reduced from 63.23nm to 34.22nm, that is reflected in the increase resolution approximately four times. Therefore, this work offers a new horizon for the development of the performance of biological and chemical sensing systems that based on measuring refractive index (RI) of analyte. [ABSTRACT FROM AUTHOR]

The Surface Plasmon Resonance (SPR) mechanism used to design a biosensor and sensitive optical sensor for different applications. This work used Matlab software to simulate and analyze SPR with gold layer thickness (40 nm) and Bismuth (Bi) layer at different eight thicknesses (from 10 to 80 nm). These layers were deposited on N_LASF9 glass prism, while the final sensing medium is the air. The analysis achieved for different wavelengths in the visible band (500-700 nm) and different refractive index (0, 0.04, 0.08 and 0.12). The properties of SPR angle (θSPR) are extracted from the incident angle θincid plot diagram. The sensitivity (S) of the suggested system is calculated within this study. The results show that the maximum sensitivity is (95.5) for thickness (20 and 30 nm) of Bi, and Δn= 0.04 at wavelength 700nm. The best sensitivity is 90 at wavelength 600 nm for thickness 40 nm for the studied refractive index. [ABSTRACT FROM AUTHOR]

A simple low-cost approach at various exposure times was utilized to generate cold plasma in the aim to fabricate AuNPs. UV-Visible spectra and X-ray diffraction were used to characterize the nanoparticles (XRD). Surface Plasmon resonance was observed in the synthesized AuNPs at 530, 540, and 533 nm. For all samples, the patterns of XRD show very intensive peaks implying the fcc crystalline structure of AuNPs. The average crystallite size of AuNPs is ranging between 20-30 nm. The observation of morphology by FESEM revealed the spherical formation of AuNPs. Doses of 100 and 200 ppm of AuNPs were adapted to investigate their effect on the blood-mixture with and without a 20-second of cold plasma exposure. The WBC components in the blood rose as the AuNPs doses increased, whereas, the amount of (pt) in the blood fell down throughout the two weeks of AuNPs doses for the groups which exposed to AuNPs only, the level of (pt) in the blood increased in the groups which are exposed to AuNPs combined with cold plasma. While the RBC unaffected. [ABSTRACT FROM AUTHOR]

This paper presents the implementation of gold nanoparticles (AuNPs) are used in the plasmonic sensor as sensing material to detect toxic materials, namely Malathion. The plasmonic sensor is susceptible to the intended toxic materials with sufficient peak resonance position, intensities and wavelength shift are measured as sensing parameters. In addition, the plasmonic sensor is simple to set up and consists of a light source connected to two arms to a duplex fibre optic. The first arm transmits light to the sample from the light source beam, and the second arm transfers the reflected light to the spectrophotometer from the sample. The AuNPs was synthesised using the Seed Mediated Growth Methods (SMGM). This method consists of two stages: seeding and growth processes and the growth times for this experiment are set to 4 hours and 8 hours. The colour changes from yellow to reddish-brown during the seeding process and from colourless to purple during the growth process. The structural results confirmed the formation of AuNPs on the substrates at (111) and (200) planes, whereas the optical responses show a single plasmon resonance peak for both samples. The 8 hours sample with higher intensity is further applied as a sensing material in the detection of Malathion. The sensitivity of the sensor system was measured by recording the changes in peak positions and intensities of the surface plasmon resonance peaks on three different mediums, namely, air, deionised water and malathion solution. Besides fast response, this sensor shows a stable response within 600 seconds during the stability test. The repeatability test has been done, and the sensor response demonstrated good repeatability over six cycles of testing, as seen by the intensities of DI water and Malathion, which almost entirely returned to their previous intensity after each medium change cycle. In conclusion, the plasmonic sensor-based AuNPs shows high sensitivity and good stability and repeatability towards toxic malathion pesticide. [ABSTRACT FROM AUTHOR]

As a mild reductant, hydrazine sulfate was utilized to synthesize silver nanoparticles (AgNPs) from AgNO3 in the capping and stabilizing of chitosan. The formation of colloid AgNPs is clearly indicated by a change of color from bluish-purple to brownish-yellow, which corresponds to a characteristic Surface Plasmon Resonance (SPR) at around 418–431 nm. UV–Vis spectroscopy revealed the influence of chitosan and silver precursor concentration on the size and shape homogeneity of AgNPs. Face-centered cubic (fcc) crystalline phase with a unit cell of 0.4098 nm is formed in spherical AgNPs with diameters of 19–20 nm. The pseudo-second reaction order governs the initial rates of AgNPs nucleation. The colloid AgNPs produced were found to be relatively stable for a month and to be affected by the concentrations of all reactans. [ABSTRACT FROM AUTHOR]

Gold nanoparticles (AuNPs) demonstrates a unique localized surface plasmonic resonance (LSPR) characteristic compared to their bulk counterpart. Plasmonic properties are useful in environmental monitoring (EM) shown by their successful application in simple and fast detection of emerging contaminants (i.e., pharmaceuticals via colorimetric and spectrometric assays. Ciprofloxacin (CIP) is a common antibiotic used to treat bacterial infections in humans and animals. Therefore, its vast application is responsible for its inevitable presence in hospital and household effluents leading to its occurrence in the environment. Hence, this study is proposing a simple, rapid, and sensitive colorimetric nanosensor for detecting and quantifying CIP in wastewater using UV-Vis spectroscopy. The presence of CIP induces the aggregation of citrate-capped AuNPs, due to its higher affinity tothe nitrogen present on CIP compared to the carboxylate of the citrate cap. This phenomenon destabilizes the AuNPs, by eliminating the electrostatic hindrance and ensures the agglomeration of the AuNPs. A color modulation of red to blue visually detects the change in the parameter, accompanied by an LSPR peak shift. The developed method displays an excellent linear relationship in the range of 0.1 – 2.0 µM (R2=0.98), with a lower limit of detection (LOD) and quantification (LOQ) of 0.39 µM and 1.2 µM, respectively. The analysis of spiked wastewater samples suggests that the method can detect a low concentration of the CIP in environmental matrices. [ABSTRACT FROM AUTHOR]

Optical sensors based on a plasmonic multilayer stack, such as metal-insulator-metal (MIM), have attracted considerable attention over the past decades owing to their high resolution and high performance compared to conventional surface plasmon resonance (CSPR) sensors for bulk sensing (BS) applications. In this paper we show that CSPR is better than MIM sensors for thin film sensing, i.e. when a dielectric sensing layer (SL) is deposited on the outermost metal layer of the structure. We demonstrate that the deposition of a thin film SL on the top of the outermost-layer of an optimized multilayer structure, i.e. MIM, strongly decreases the evanescent electric field and the field enhancement at metal-SL interface and decreases the sensor's sensitivity for MIM versus CSPR. By considering the theoretical and experimental results we demontrated that CSPR is more suitable than MIM for thin films sensing applications. [ABSTRACT FROM AUTHOR]

We studied by FDTD computer simulations the dependence of the surface plasmon resonances in linearly arranged gold nanospheres on incident light polarization, spheres number and diameter, and interparticle gap. The observed scattering spectra of large particles show a particularly interesting behaviour, with coupled plasmon resonances that can be either red or blue shifting with the modification of the interparticle gap. The sensitivity of the various observed coupled plasmon modes to refractive index variations is then evaluated. [ABSTRACT FROM AUTHOR]

Silver nano particles holds an extensive variety of applications in diverse fields ranging from photonics to electronics, bio-sensors, conducting materials, space, medicine, pollution control and monitoring. Nanoparticles are on its way to conquer world with its peculiar properties like electric conductivity, optical properties, good biocompatibility etc. These nanoparticles on combining with other materials in preparation of composite material can enhance property of materials or the properties can be toned. Cinnamomum tamala leaf, which is a common herb, widely used for culinary and medicinal purposes in India is used as the substrate for the study. The synthesized nanoparticles were characterized by UV-Visible spectroscopy and X-Ray diffraction. Further, the prepared nanoparticles were studied for its environmental application in the detection of heavy metal and finally pave way for the development of biosensors in an ecofriendly and cost-effective way. In addition, the anti-bacterial and anti-fungicidal properties of the particles synthesized were assessed following standard procedures and they exhibit excellent anti-microbial activity against bacteria. [ABSTRACT FROM AUTHOR]

Plasmonic nanostructures based on noble metals have potential for highly sensitive chemical sensing platforms. In this study, silver coated 150nm silica nanoparticles have been investigated for mercury sensing in aqueous medium. Thickness of silver shell and size of silica core has been found to significantly impact optical properties of core shell plasmonic nanostructures. UV-Vis absorption spectra have been used to identify the sensitivity of silver nanoshells to Hg2+. Silver forms amalgam with Hg and the redox potentials are appropriate for galvanic replacement reaction with Hg2+. Due to amalgamation a blue shift in the localized surface Plasmon resonance is expected and which has been confirmed from UV-Vis results. Selectivity of the sensor has been established for calcium, barium, iron and cobalt metal ions since silver does not form amalgam with majority of transition metal ions. [ABSTRACT FROM AUTHOR]

Quantum dots (QDs) as Nanocarriers (NCs) can be used to release the drug to its target, which enhances the bioavailability of the drug in the biomedical field. It also increases the stability of the drug and improves the targeted drug absorption, also increases the distribution and drug metabolism process. The development of quantum dot NCs has recently become the focus of study in the nanomedical field. Their specific photoluminescence and electronic properties, including large and continuous absorption spectra, small visible to emission spectra of the near-infrared range, long light endurance, and high visibility, make them perfect as such suitable probe materials in (bio)sensing or immunosensing platforms. They can also be designed for other biomedical applications, such as fluorescent assays for disease diagnosis and drug discovery. In addition to other influential forms of their new applications in analytical chemistry, drug delivery, biosensors and immunoassay, their synthesis processes, surface modification, and bioconjugation, this article discusses the physical and chemical characteristics of QDs. [ABSTRACT FROM AUTHOR]

Colorimetric sensors are extensively explored class of optical biosensors due to the visible eye detection enabled by them. An efficient way of colorimetric sensing can be achieved by studying the surface plasmon resonance (SPR) properties of noble metal nanoparticles like gold, silver etc. The SPR band of gold nanoparticles is influenced not only by their size and shape but also by the dielectric properties of the environment and the proximity of other nanoparticles which make them most suitable candidates for colorimetric sensing applications. In this work, we developed a novel, rapid, enzyme free colorimetric assay for glucose level determination. The normal levels of glucose in human blood range from3.8 to 6.9 mM approximately, although these levels may change during the day, being lower upon fasting and reaching a peak in post-cenal states. Both high and low glycemic levels are detrimental for health status. Glucose of various physiological concentrations (3 mM-50 mM) acts simultaneously as reducing and capping agent for the gold nanoparticle synthesis from tetrachloroauric acid enabling its label free detection. The increase in glucose concentration from normal to diabetic range cause a colour change from blue to red. The localized surface plasmon resonance (LSPR) peak is shifted from 520 to 580 nm due to the agglomeration of gold nanoparticles at lower concentrations of glucose. [ABSTRACT FROM AUTHOR]

Nowadays fast response of surface plasmon resonance is widely used for refractive index sensing applications. The plasma frequency of the conventional metals is in the UV-visible region. This paper reports the simulation of the excitation of surface plasmons in RF magnetron sputtered titanium metal films. Titanium metal films were coated onto glass substrates using titanium metal target. The microstructure of the films was studied by the FE-SEM image. The dielectric function of the films was extracted from the reflectance spectra using the Drude Lorentz approximation. The dependency of films thickness on SPR excitation, and the refractive index sensing property of the film were studied in this work. The results of these studies are discussed in detail. [ABSTRACT FROM AUTHOR]

Bimetallic Ag-Cu (Ag-core/Cu-shell) and Cu-Ag (Cu–core/Ag-shell) nanocomposite soda lime glasses are synthesised by sequential ion exchange method. Optical absorption spectroscopy has been used to investigate these core-shell metal nanoclusters, and corresponding theoretical spectra were simulated and compared. Calculations were performed using Mie's theory for core-shell nanoclusters in which core radius is kept constant and shell thickness is varied which results blue shift in SPR peak position. The tunable features of surface plasmon resonance of core-shell metal nanoclusters depend on the size, shape, structure, and refractive index of an embedded medium. The effective dielectric constants of various environments like air, soda lime, crown, flint, and sapphire are used to simulate the absorption spectra of both core-shell nanoclusters, which results redshift in surface plasmon resonance peaks. It clearly shows that the SPR peak position not only depends on the embedded metal dielectric constant and also that of embedding medium. [ABSTRACT FROM AUTHOR]

Background: At the molecular level, nanotechnology investigates many exciting approaches in the field of materials science, and silver nanoparticles (AgNPs) are of particular interest in the current context. Furthermore, biological methods for the synthesis of silver nanoparticles (AgNPs) have gained exceptional attention as these methods not only involve lesser time and energy consumption compared to physical and chemical processes but are also rapid, efficient, and non-toxic. Methods: This study reported the biosynthesis of AgNPs by reducing silver nitrate solutions (AgNO3) into AgNPs using leaves extract of Dodonaea viscosa as a reducing agent. The effective temperature of reaction on the biosynthesis of AgNPs and stability study of AgNPs were investigated. The synthesized AgNPs and evaluated their clinical application was made. UV-visible spectroscopy showed the Surface Plasmon Resonance (SPR) has appeared at 463 nm. Fourier Transform Infrared spectroscopy (FT-IR) analysis confirmed the role of water-soluble Phyto-compounds of Dodonaea extract to reduce silver ions to silver nanoparticles. The crystalline structure was revealed by X-ray diffraction (XRD), with an average crystal size estimated at 37.665 nm for silver nanoparticles. The topography of the surface and the size of the particles with an average length of 60.22 nm were shown in the atomic force (AFM) microscopy analysis. In addition, Scanning Electron Microscopy (SEM) technique showed the dimension and the shape of AgNPs. Results: The silver nanoparticles synthesized by green method using extracts of Dodonaea viscosa indicated prolonged the coagulation time by increasing prothrombin time (PT) and activated partial thromboplastin time (APTT). Besides, silver nanoparticles have a little impact on the hemolysis of red blood cells of human. [ABSTRACT FROM AUTHOR]

A long range surface plasmon resonance (LR-SPR) sensor with antimonene and Cytop is proposed to enhance the detection accuracy (DA) and figure of merit (FOM). In contrast to conventional LRSPR structure with aluminium (Al) metal, antimonene coated the metal surface helps to improve biomolecules adsorption and prevents the oxidation of Al metal. Low loss LR-SPPs are induced at both sides of metal film due to closer refractive index (RI) of Cytop and sensing medium. Hence, the proposed LR-SPR sensor confirmed high DA (50 deg.−1) and highest FOM (894.96 RIU−1) value. This paper shows meaningful results for the designing and development of LRSPR sensor for the sensing of the large scale biomolecules. [ABSTRACT FROM AUTHOR]

This study aims to synthesize and characterize the colloidal silver nanoparticles (SNPs) in polyvinylpyrolidone (PVP) liquid with high purity by using the pulsed laser ablation (PLA) procedure. Silver plate, which was placed into PVP liquid inside a cuvette, was shot by a laser beam to produce SNPs colloid. PVP is used as a polymer medium that is expected to make SNPs smaller, stable, and not easily agglomerated. After 150 minutes of laser stroke, colloidal SNPs were successfully produced indicated by discoloration as golden yellow. To know other characterizations, we used a Transmission Electron Microscope (TEM) method and Ultraviolet-Visible (UV-Vis) spectrophotometer method. The TEM image of SNPs marked that these nanoparticles had a spherical shape. The average diameter of the SNPs was 17 nm. The UV-Vis method resulting in the peak of surface plasmon resonance at wavelength 408 nm. [ABSTRACT FROM AUTHOR]

Biosynthesis of silver nanoparticles (AgNPs) using plant extract is currently considered an environmentally friendly method. This study aimed to synthesize AgNPs by reaction of silver nitrate salt and pomelo green peel extract. To obtain a high yield of AgNPs, the factors involved in AgNPs synthesis, such as a combination of AgNO3 concentrations (1 mM, 2 mM and 3mM) with pH (4.8, 5, 6, 7 and 8) and reaction time (24 and 48 h) and format of plant extract pouring was optimized. Changing reaction color from yellow to yellowish-brown after 10 min heating (60°C) of AgNO3 and that of plant extract indicated the success of AgNPs formation. Additionally, the surface plasmon resonance (SPR) detected at wavelengths of 402-411 nm by UV-Vis spectrophotometer which is a unique optical property of AgNPs also confirmed the synthesis of metal Ag particles in nanoscale size. The optimum condition for AgNPs synthesis using the extract of pomelo green peel was 2 mM AgNO3, pH 8 and a reaction time of 24 h. In addition to the AgNPs synthesis and characterization, the application of the AgNPs to increase biomass and bioactive compounds of Dendrobium officinale protocorm-like bodies (PLBs) were also studied. After culturing for 4 weeks, the supplementation of AgNPs at 0, 25 and 50 mg/L in plant culture medium showed a non-significant difference of biomass growth ratio (dry basis), while the higher amounts (75 and 100 mg/L AgNPs) showed a negative effect on biomass increase. The phenolic and flavonoid contents of the extracts from orchid protocorms cultured in a medium supplemented with 25 and 50 mg/L AgNPs were higher than the others. Moreover, the antioxidant activity of the extracts from protocorms treated with all tested AgNPs was significantly higher than the control. This suggested that the synthesized AgNPs can increase bioactive compounds and the antioxidant activity of D. officinale PLBs. [ABSTRACT FROM AUTHOR]

Magnetic nanoparticle is a particle in nano size (1-100nm) that can be manipulated using magnetic fields. The interaction between the magnetic nanoparticles and the target-analyte plays a significant role in bio-sensing applications. This study focuses on understanding the magnetic nanoparticle's biosensor behaviour in detecting protein molecules as the target-analyte using the nanoHUB online simulation tool. The simulation enables the observation of the various magnetic nanoparticles sensing behaviour towards protein detection. This study simulates variation of magnetic nanoparticle-based biosensor using the parameters obtained by published work from other research groups and systematically investigates the sensing behaviour. Based on the results obtained, it can be observed that the simulation results show a steady-state behaviour for all the magnetic nanoparticle-based biosensor indicating that the protein captured are in the same size (nanometre size) as the sensor. This study also indicates that the magnetic nanoparticle size is inversely proportional to the response time (or settling time) where bigger size of magnetic nanoparticle leads to a reduction of the response time. It is also worth to note that the magnetic nanoparticles with higher density results in faster settling time due to reduction of the diffusion rate. Also, the results show the settling time is affected by the density compared to the size of the magnetic nanoparticles. Further investigation on the different type of target-analyte (aside from protein) is suggested for the in-depth understanding of the magnetic nanoparticle-based biosensor. [ABSTRACT FROM AUTHOR]

The spread of the COVID-19 virus out of control makes rapid detection develop immediately to reduce the transmission of the virus massively. PCR-based diagnostic tests, which have become the golden standard for detection, are still long and expensive. Therefore, another method that can become a rapid detection sensor is a solution-phase-based LSPR (localized surface plasmon resonance) biosensor. The detection results are fast, do not require sample preparation, and use a small sample. The need for highly sensitive biosensors makes selecting nanomaterials for LSPR important because size and shape determine plasmonic properties. Many studies have studied the effect of morphology on plasmonic properties. It is currently known that the LSPR effect is much more substantial for sharp nanoparticles. It is expected to make a more significant contribution to the sensitivity of the sensor. In this study, spherical AuNP was compared to the bipyramidal AuNP to see the performance. However, the sensor in the solution phase main thing to consider is the condition of the solution, such as pH and ionic stability (using buffer). Therefore, we studied buffer optimization to stabilize AuNS and AuNB, then conjugated with scFv to detect the presence of the SARS-CoV-2 virus. The result shows that AuNS and AuNB were stable with the addition of carbonate-bicarbonate buffer (pH 9.6), and AuNB could detect the presence of SARS-Cov-2 and had better performance than AuNS. [ABSTRACT FROM AUTHOR]

Coronavirus disease (COVID-19) confirmed cases spread worldwide and still rapidly increasing. Early detection and screening test is crucial to control the spread of the infection and prevent hospitals from collapse in handling COVID patients. Therefore, the development of point-of-care testing that allows rapid detection yet accuracy without utilizing laboratory is needed. Electrochemical biosensors can be a good solution by using SPCE due to allowing portable testing, simplicity, ease of operation, and the potential for mass production. Modification of the working electrode with nanomaterial is supposed to improve its analytical performance. AuNPs are potential materials to electrodeposited on the working electrode of SPCE to create a more significant electrode reaction, enhance the electron transfer, increase the conductivity, and act as anchoring materials due to their ability to strongly bind with thiolated protein. In this work, the scFv is immobilized on to gold nanoparticles-modified electrode as a bioreceptor to detect SARS-CoV-2 RBD. The use of scFv in this study will enhance antibody performance and reduce assay costs since it has the same or better specificity as the whole antibody in antigen binding. The electrochemical measurements show the successfully developed proof of concept of SARS-CoV-2 RBD biosensor with the change of current oxidation peak resulting from scFv and RBD incubation was 55.8% and 14.5%, respectively. [ABSTRACT FROM AUTHOR]

Planar structures of SiO2/SiON for waveguide sensors with a plasmonic Au layer are investigated by total internal reflection ellipsometry (TIRE). Au layers with various thicknesses from 32 nm to 85 nm are studied. We point out the influence of thickness of SiON layer as a high refractive index guiding material on the surface plasmon excitation. The discussion on the suitability of the considered materials for waveguide sensor applications based on surface plasmon resonance with conventional LEDs at 650 nm is also included. [ABSTRACT FROM AUTHOR]

Biosynthesis of nanoparticles is attractive to researchers because some of the biologically active ingredients in the plants help in green synthesis. In this study, we have developed a single-step, cost-effective, and eco-friendly method for the synthesis of Silver nanoparticles (AgNPs) using the aqueous plant leaves extract of Laggera crispata (Vahl) Hpper and J.R.l Wood. AgNPs were biosynthesized using Laggera crispata (Vahl) Hpper and J.R.l Wood leaves extract as reducing, capping, and stabilizing agent. The AgNPs began to form just after the addition of aqueous extract of Laggera plant to the aqueous solution of Silver nitrate (AgNO3) at room temperature. The biosynthesized AgNPs were characterized by different techniques, such as Fourier Transform Infrared (FTIR) spectroscopy, X-ray Diffraction (XRD), and UV-Visible Spectroscopy. The absorption spectra obtained from UV-Visible spectroscopy showed a sharp Surface Plasmon Resonance (SPR) peak at 451 nm which confirmed the formation of AgNPs. The average particle size of AgNPs was 53 nm as determined by X-ray Diffraction measurement. The FTIR study showed characteristic peaks corresponding to the functional groups that act as capping and stabilizing agent to AgNPs. [ABSTRACT FROM AUTHOR]

Nanostructured plasmonic surfaces have been the subject of many biosensing applications exploiting surface-enhanced fluorescence in the last few years. For this reason, we investigated the refractive index dependence of the coupling mechanism between the plasmonic modes and the fluorescence processes. The results show that the fluorescence emission spectral shape is controlled by the plasmonic field distribution, together with the enhancement of its signal. By altering the refractive index at the plasmonic active surface, the resonance conditions of the plasmonic modes change, resulting in a reshaping of fluorescence emission and a different spectral distribution of the largest enhancement regions. [ABSTRACT FROM AUTHOR]

Nanoparticles exhibits size and shape-dependent properties, thus each with unique character and use. Caulerpa prolifera, Sarconema filiforme, and Padina tetrastromatica; were collected from Suez Canal, Egypt, for silver nanoparticles (AgNPs) fabrication. The algal extract was added to an aqueous solution of AgNO3, and AgNPs synthesis was monitored with an hourly interval by UV-Vis Scan. Physical factors, pH, temperature, and light were studied. Depending on the surface plasmon resonances (SPR) bands and λ-max, AgNPs synthesized using Padina at pH 7, 30 ⁰C after 168 h in the dark were characterized. λ-max was at 430 nm, XRD indicated the formation of AgNPs, HR-TEM images mainly showed spherical particles with size ranging from 5 to 25 nm, and Zeta-potential insinuated AgNPs stability. FTIR analysis of the algal extracts indicated diverse phycoconstituents. This study reveals a diverse response of phyconanofabrication to physical factors, and Padina tetrastromatica is a green and cost-effective AgNPs factory. [ABSTRACT FROM AUTHOR]

The exceptional antibacterial properties of silver nanoparticles (AgNP) fascinated many researchers to study and exploit this nanomaterial in various applications as a potential antibacterial agent. Nevertheless, it is significant to establish a safe and environmentally friendly synthesis approach. In this sense, green synthesis of AgNP was employed using Orthosiphon aristatus (Misai Kucing) herbal plant as a reducing and capping agent. The brown colour formation of Oa-AgNP colloidal with surface plasmon resonance peak between 410 nm to 480 nm confirmed the reduction of Ag ions into AgNP. The involvement of secondary metabolites as a capping agent was verified through Fourier Transform Infrared Spectroscopy (FTIR) analysis. The crystalline nature of the nanoparticles was characterized using X-ray diffraction (XRD), selected area electron diffraction (SAED) and transmission electron microscopy (TEM). Complementary, the antibacterial activities of the Oa-AgNP were evaluated by disc diffusion technique (DDT) against marine bacteria Bacillus niabensis (16.2±0.23 mm) and Alteromonas litorea (14.2±0.15 mm). While minimum inhibition concentration (MIC) values of the sample against B. niabensis and A. litorea were recorded at 2.5 µg/mL and 5 µg/mL, respectively. The observed results signify the potential of synthesized AgNP using O. aristatus as an effective antibacterial agent specifically for marine-related applications. [ABSTRACT FROM AUTHOR]

A chemical sensor of refractive index variations, which possesses prescribed resolution, is designed, implemented and tested. Enhancement of coupling forces by the Bloch surface waves is achieved by incorporating a one-dimensional (1-D) photonic crystal (PC) into the classical Kretschmann arrangement of surface plasmon resonance. The numerical optimization approach was used to establish geometrical parameters of the photonic crystal with prescribed material constituents. The number of layers, their thicknesses, and a specific role of the binding dielectric layer between the PC and the metallic film are discussed in detail. Experiments with optimally designed sensor samples compare favourably with model simulations. [ABSTRACT FROM AUTHOR]

Optical fibre sensor with their properties and simple design represent an amazing sensing way to monitor the chemical concentration and a key issue for a revolution in medical devices. The sensor that designed had not dependent on a complex structure or expensive parts. The uncomplicated design was using 40nm of a gold layer as a surface plasmon resonance coating for 10 mm of commercial, multi-mode fibre to assess urea concentration at (4, 6, 8, 10 mM). Experimental results demonstrate that a sensor's sensitivity for the area was increasing from 3.5 to 25µm/nu with the urea concentration vary from 2 to 10 mm. The simple design and setup make the optical sensor was an efficient method for different biological systems. [ABSTRACT FROM AUTHOR]

This paper introduces a review of the layers used in surface plasmon resonance (SPR) with different types of optical fiber and different designs. Surface plasmon resonance (SPR) offers exceptional advantages, such as label-free, in-situ, and real-time measurement abilities that facilitate the study of molecular or chemical binding events that can be used as highly sensitive tools for biosensing. We found in a variety of surface plasmon resonance (SPR) optoelectronics devices, gold and silver are the most commonly employed metals, and adding a thin dielectric over layer with a relatively high RI has been used to enhance the sensitivity of SPR sensors. [ABSTRACT FROM AUTHOR]

Surface plasmon resonance (SPR) sensing method has expanded widely in using sophisticated methodologies to study biological and chemical processes. These methods vary between practical and simulation techniques to enhance and optimize different designs. This paper focuses on the surface plasmon in different fields, applications and uses it for different purposes. Clarifying the similitudes and contrasts between the works was done sincerely, examining various perspectives held by other authors. Investigation of the optical system methods. Assessment of how each optical method adds to the surface plasmon sensor technique. In the end, it sums up this review paper discusses the fundamentals of plasmonic-based sensors, coupling methods, and studies the latest additive tools for couplings such as a prism, optical fiber, waveguide, and grating. The most crucial goal of this paper is highlighting the application used surface plasmon and tools to reach the primary research objective. [ABSTRACT FROM AUTHOR]

In this paper, a germanium sulfide (GeS) based surface plasmon resonance (SPR) biosensor is designed and analyzed, consisting of fused silica prisms, gold, graphene, and GeS layers. The aim of this proposed SPR biosensor is to enhance the performance parameters including the accuracy of detection, sensitivity and quality factor by monitoring the recombination of cDNA and ssDNA on its sensing surface. The proposed structure is designed and numerically analyzed using FDTD technique through a Multiphysics simulation tool. A good agreement was found between the simulation results and those derived from the theoretical formula using Fresnel equations and matrix theory. As compared to recent publications, the proposed biosensor exhibits significant improvements in performance parameters. In addition, Furthermore, the FWHM is examined in relation to the number of graphene layers. [ABSTRACT FROM AUTHOR]

In this study, gold nanoparticles (AuNPs) were synthesized using a plasma jet system at different exposure times. Using ultraviolet, visible spectra, X-ray diffraction, the nanoparticles were characterized (XRD). A Plasmon surface resonance concentrated at 530, 540, and 533 nm for the prepared AuNPs. The pattern of XRD showed that the extreme peaks of the film reflect crystalline existence. The face-centered cubic structure of the gold nanoparticles was prepared for all samples, with an average crystallite size of 25-40 nm. The effect of AuNPs in vivo on liver function levels was measured. For all doses, we notice an increase in the ranks of liver function in the blood during the period of dosing, and it begins to decrease when the dosing is left. [ABSTRACT FROM AUTHOR]

The phenomenon of surface plasmon resonance is often used in various devices of photonics and optoelectronics, for which the speed of response and the ability to control the parameters of devices are important. The use of high- temperature superconductors as plasmonic structures has a number of features, the most important of which is low damping. In this paper, we consider the characteristic of surface plasmon resonance in nanocomposite structures consisting of a dielectric matrix with superconducting inclusions. The temperature dependence of the dielectric constant of the superconductor is calculated taking into account the two-fluid model. It is shown that the surface plasmon frequency highly depends on the temperature, which makes it possible for the practical application of nanocomposite superconductors in the design of bandpass notch filters. [ABSTRACT FROM AUTHOR]

The present study aims at green synthesis of silver oxide nanoparticles (Ag2O NPs). The synthesis of Ag2O NPs was achieved using rhizome extract of plant B. ciliata as a promoter of reduction and stabilization. Characterization of Ag2O NPs were performed using UV–Vis(Ultraviolet–Visible Spectroscopy), XRD (X-ray Diffraction), DLS (Dynamic Light Scattering), FTIR (Fourier Transform Infrared Spectroscopy), SEM (Scanning Electron Microscopy) and EDX (Energy-Dispersive X-ray Analysis). The formation of Ag2O NPs is confirmed by the signatory brown coloured appearance of the solution. UV visible spectrum clearly reveals the formation of nanoparticles and intense surface plasmon resonance band at wavelength of 400-450 nm. FTIR spectrum confirms the distinct interacting groups of nanoparticles are present and are responsible for capping the biomolecules.Studies on XRD showed a high degree of natural crystallinity. The mean particle size investigated using DLS was found in between 10–20 nm. SEM analyses Ag2O NPs aggregate formation with EDX spectrum and spherical-like formation, which confirms the presence of Ag and O in the synthesised NPs. Green synthesis is therefore always a highly recommended low cost and eco-friendly method for large-scale industrial as well as medicinal applications. [ABSTRACT FROM AUTHOR]