Single Surface Plasmon Resonance Research Articles

Study on fabrication and optical properties of monodisperse Ag-Au alloy nanostructure

This study addresses challenges in various fields by creating a new method for uniform, size- and composition-controlled Ag-Au alloy nanoparticles in organic solvents. Building on prior research, we demonstrate control over nanoparticle properties by varying complexing agents, surfactants, and reducing agents. Optimal conditions using surfactant SOA and reducing agent TBAB yielded small, monodisperse Ag nanoparticles ideal for alloying with Au. The reaction time significantly impacts final morphology and surface plasmon resonance (SPR) properties of the resultant Ag-Au alloy nanoparticles. Interestingly, Au nanoparticles formed under identical conditions shared a similar size with 60-minute Ag-Au alloys, evidenced by a single SPR peak at 520 nm. This control over Ag-Au nanoalloy composition and size opens doors for promising applications.

Structure Design and Sensitivity Optimization of Optical Fiber Biosensor Based Au Nano Column - TiO2 Heterostructure

An investigation on a single mode optical fiber sensor-based surface plasmon resonance was carried out in this work. A titanium dioxide (TiO2) coated gold Nano-column (Au) are deposited on the proposed sensor and theoretically analyzed using COMSOL Muliphysics software 5.3. Presence of TiO2 over the Au Nano-column can improve the sensitivity of the sensor and tune the resonance peak of transmission spectrum from visible region to near-infrared region. The size effect of TiO2 nanoparticles on the sensor performance is studied. The optimum parameters of such as Au size and separation width between the Au Nano-column have been selected to enhance the performance of the sensor. In comparison, the sensor with TiO2 over Au Nano-column is significantly improve the sensitivity and develop the sensor performance. The greater sensitivity of 5243.76 nm/RIU (refractive index unit) is obtained of sensor with TiO2 over Au Nano-column when the external refractive index of analyte is varying from 1.33 to 1.39, while sensitivity of the sensor coated with Au Nano-column is obtained to be 4643.17 nm/RIU for the same analyte range. Above results can be used to predict the best parameters values of the sensor that corresponding to the greatest sensitivities of detection and finally opening new study in the field of gas sensors. HIGHLIGHTS Optical fiber biosensors are a devices that use to measure the analyte by using the optical field Optical fiber biosensors have a high detection speed and low-cost, compared to congenital sensors The optical fiber sensors based SPR are widely used for biosensor applications The novelty in this research is the fabricate of optical fiber sensor coated with TiO2 over Au Nano-column based SPR foe gas detection GRAPHICAL ABSTRACT

Fluorescence quenching of fluorescein dye using silver nanoparticles

Fluorescence quenching is indeed a versatile and widely used technique in various scientific disciplines, including chemistry, biology, and medicine. It provides valuable information about the behaviour of small molecules in organized systems and offers insights into the properties of the microenvironments surrounding the fluorescent probe and quencher molecules. In the present work, we report the synthesis of citrate-stabilized silver nanoparticles and also investigate the effect of the prepared silver nanoparticles on the fluorescence luminous intensity of fluorescein dye with different concentrations of silver nanoparticles. The UV–visible spectrometer is used to study the absorption properties of silver nanoparticles. We have obtained a single surface plasmon resonance band, which indicates the isotropic nature of particles. The particle size was obtained from the absorption spectra, using the Mie scattering theory. The luminous intensity of fluorescein dye was found to be quenched in addition to silver nanoparticles. The morphological analysis is done using SEM.

L-cysteine/MoS2 modified robust surface plasmon resonance optical fiber sensor for sensing of Ferritin and IgG

L-cysteine conjugated molybdenum disulphide (MoS2) nanosheets have been covalently attached to a gold coated surface plasmon resonance (SPR) optical fiber to prepare a robust and stable sensor. Owing to the multifunctionality of the deposited nanosheet conjugate, the antibodies are also covalently conjugated in the subsequent step to realize the design of a SPR optical fiber biosensor for the two important bioanalytes namely, Ferritin and Immunoglobin G (IgG). The different stages of the biosensor preparation have been characterized and verified with microscopic and spectroscopic techniques. A uniform and stable deposition of the L-cysteine/MoS2 nanosheets has allowed the biosensor to be reused for multiple times. Unlike the peeling-off of the MoS2 coatings from the gold layer reported previously in the case of physically adsorbed nanomaterial, the herein adopted strategy addresses this critical concern. It has also been possible to use the single SPR fiber for both Ferritin and IgG bioassay experiments by regenerating the sensor and immobilizing two different antibodies in separate steps. For ferritin, the biosensor has delivered a linear sensor response (SPR wavelength shifts) in the concentration range of 50–400 ng/mL, while IgG has been successfully sensed from 50 to 250 µg/mL. The limit of detection for Ferritin and IgG analysis have been estimated to be 12 ng/mL and 7.2 µg/mL, respectively. The biosensors have also been verified for their specificity for the targeted molecule only. A uniform and stable deposition of the nanomaterial conjugate, reproducibility, regeneration capacity, a good sensitivity, and the specificity can be highlighted as some of key features of the L-cysteine/MoS2 optical fiber biosensor. The system can be advocated as a useful biosensor setup for the sensitive biosensing of Ferritin and IgG.

The Fabrication of Gold–Silver Bimetallic Colloids by Microplasma: A Worthwhile Strategy for Counteracting the Surface Activity of Avian Influenza Virus

In the present project, fructose-stabilized gold, silver and gold–silver bimetallic colloids have been synthesized by the electrochemical reduction of HAuCl4·3H2O (Au precursor) and AgNO3 (Ag precursor), employing the atmospheric pressure microplasma technique. X-Ray Diffraction patterns of gold–silver bimetallic particles exhibit (111), (200) and (220) planes identical to gold and silver NPs depicting FCC structures. The decrease in the peak intensities of Au–Ag (111) and Au–Ag (200) as compared to those of Au (111) and (200) is due to the formation of Au–Ag alloys. The FE-SEM image of gold–silver bimetallic NPs has revealed an adequate change in morphology as compared to the morphology of gold NPs and silver NPs. The majority of the gold–silver bimetallic NPs are spherical and are uniformly dispersed. The EDS spectra of (Au–Ag) confirm the presence of metallic gold and silver. The appearance of a single Surface Plasmon Resonance (SPR) peak in the UV–VIS absorption spectra of gold–silver colloids and its position in between the SPR peaks of the UV–VIS absorption spectra of gold and silver colloids justify the formation of gold–silver bimetallic alloy particles. In DLS measurements, the size distribution of gold–silver bimetallic colloids carries a narrow range 55 to 117 nm as compared to the size distribution of gold and silver colloids. The compatibility of the sizes of these colloids and the influenza virus belonging to the Orthomyxoviruses family (size range 80–300 nm with different morphologies) are assumed to stand responsible for an effective bio-conjunction with Influenza viruses. Au–Ag bimetallic nanostructures have synergistically improved their antiviral activity against H9N2 influenza virus as compared to monometallic AuNPs and AgNPs. Thus, the Au–Ag nanostructured alliance has been proven to be more effective and is capable of manifesting high antiviral efficacy.

Violet phosphorus-enhanced plug-and-play double-lane fiber optic surface plasmon resonance refractometer

The fiber optic surface plasmon resonance (SPR) technologies can directly detect the change of the refractive index on the surface of the sensor, caused by the interaction of biochemical molecules. Fiber optic SPR technologies have advantages of small size, low cost, no labeling, high sensitivity, and are easy to realize the miniaturization, multi-parameter, real-time and <i>in-situ</i> detection. Two types of probe-type fiber optic SPR refractometers are constructed based on the novel two-dimensional nanomaterial, i.e., violet phosphorus (VP), the mature fabrication and characterization technologies. The fabrication processes of the fiber optic SPR refractometers are first introduced, and then the feasibility of the fabrication processes is verified via multiple characterization methods. In terms of the signal demodulation, the noise of the resonance spectrum is suppressed by the variational mode decomposition algorithm, and the resonance wavelength is interrogated and monitored in real time by the centroid method. The refractive index sensing performances of the near-field enhanced fiber optic SPR refractometers coated with different layers of VP are investigated. With the increase of the VP layer number, the resonance spectrum exhibits redshift and broadening and the sensitivity is enhanced. The refractive index sensing performance of the nearly guided wave fiber optic SPR refractometer is also investigated. In the low refractive index range of 1.33－1.34 corresponding to the refractive index of the low-concentration biological solution, the sensitivity and the figure of merit of the near-field enhanced fiber optic SPR refractometer with the sensing structure of fiber core/VP dielectric layer/Au layer/sample layer reach to 2335.64 nm/RIU and 24.15 RIU<sup>–1</sup>, respectively, which are 1.31 times and 1.25 times higher than the counterparts of the single Au layer fiber optic SPR refractometer, respectively. The sensitivity and the figure of merit of the nearly guided wave fiber optic SPR refractometer with the sensing structure of fiber core/Au layer/VP dielectric layer/sample layer can reach to 2802.06 nm/RIU and 22.53 RIU<sup>–1</sup>, respectively, which are 1.57 times and 1.16 times higher than the counterparts of the single Au layer fiber optic SPR refractometer. Finally, the near-field enhanced SPR and the nearly guided wave SPR are integrated into a single fiber probe to achieve the double-lane sensing. The fiber optic SPR refractometers developed in this study can realize the high-sensitivity, plug-and-play and double-lane detection of the combination of surface refractive index and volume refractive index. The probe-type refractometer also provides a new idea for detecting multi-type protein molecules and heavy metal ions in the biochemical field.

Investigation of the in vitro antibacterial, cytotoxic and in vivo analgesic effects of silver nanoparticles coated with Centella asiatica plant extract

In recent years, researchers have shown an increased interest in using medicinal plants for the synthesis of silver nanoparticles (AgNPs) having various therapeutic properties. Centella asiatica (CA), a medicinal plant, has been used to treat minor burn wounds, psoriasis, and hypertrophic wounds among many other pathological conditions. The current study aimed to synthesize CA coated AgNPs (CA-AgNPs) with appropriate biocompatibility and various therapeutic properties, including antimicrobial and analgesic activities. The synthesized CA-AgNPs were characterized by ultraviolet-visible (UV-Vis) spectroscopy, zeta potential measurements, and fourier transform infrared (FT-IR) spectroscopy. The formation of spherical CA-AgNPs was confirmed by a single surface plasmon resonance (SPR) peak emerging at 420 nm wavelength by UV-Vis. The average hydrodynamic diameter and zeta potential of the particles were found to be 29.5 nm and -24.5 mV, respectively. The FT-IR analyses showed that the AgNPs were coated and stabilized by bioactive compounds from the CA extract. MTT cytotoxicity assay revealed that CA-AgNPs at ≤1 mM concentrations exhibited biocompatibility for L929 fibroblast cells. The antimicrobial activity of CA-AgNPs was confirmed by significant inhibition of Staphylococcus aureus and Escherichia coli. In addition, the analgesic effect of CA-AgNPs was investigated for the first time in the literature by tail-flick and hot plate methods, and statistically significant results were obtained for both methods. Taken together, these results suggest that CA-AgNPs can be used as an effective antibacterial and analgesic agent in a variety of biomedical applications, including coating wound dressings.

Single and bimetal-based surface plasmon resonance sensor using AlN-TMDC heterostructure: a comparison study

Single and bimetal-based surface plasmon resonance sensor using AlN-TMDC heterostructure: a comparison study

MXene (Ti3C2Tx) coated highly-sensitive D-shaped photonic crystal fiber based SPR-biosensor

In this paper, a D-shaped surface plasmon resonance (SPR) refractive index (RI) based biosensor is reported for the earlier detection of various bio-analytes. The lattice of D-shaped photonic crystal fiber (PCF) offers a modified rhombus pattern for cladding air holes. D-shaped PCF is an open channel structure that fundamentally provides ease while interacting with different bio-analytes as compared to closed channels SPRs. A nanoscale MXene (Ti3C2Tx) layer is introduced with a uniform coating that drastically enhances the sensor’s sensitivity and performance. Finite element method (FEM) is employed to determine dispersion characteristics to acquire the confinement loss spectra as a function of wavelength for various bio-analytes. SPR shifts the resonant interference dip when RI of bio-analytes changes. The proposed SPR sensor with Au/ Ti3C2Tx layer exhibits maximum RI sensitivity of 47,260 nm/RIU at an analyte refractive index of 1.42 with a detection resolution of 2.11 × 10−6 RIU, which is 1.7 times higher than that of a single Au-layer SPR sensor. Moreover, it detects a wider range of bio-analytes (i.e., 1.30–1.43) using a third-order polynomial fitting function corresponding to the wavelength shift. It covers the detection of most known bio-analytes, i.e., cancerous cervical, breast and blood cells, adrenal gland, glucose concentration, proteins, viruses or DNA/RNA, etc.

Gold (Au), Silver (Ag) and Bimetallic Au/Ag Core-Shell Nanoparticles: Synthesis and Applications in 4-Nitrophenol Reduction Reactions

Au, Ag, and Au/Ag core-shell nanoparticles (NPs) were synthesized in aqueous solution by chemical reduction. UV-Vis absorption spectra confirmed a single surface plasmon resonance (SPR) peak for Au and Ag NPs, at 520 nm and 419 nm, respectively. Au/Ag core-shell NPs' UV-Vis spectra showed two distinct peaks at 385 and 480 nm, confirming a core-shell structure different from its alloy counterpart. Transmission electron microscopy (TEM) shows a relatively uniform spherical shape for both Au and core-shell Au/Ag NPs, while Ag NPs have a variety of forms such as a prism, rod, and spherical. The average size of the synthesized nanoparticles was quite similar, between 18 and 25 nm. The 4-nitrophenol reduction reaction model was used to study the catalytic ability of nanoparticles where Au/Ag core-shell NPs showed higher catalytic activity than the other monometallic NPs used in this study.

Development of EPS-rich herbal shampoo base fermented using Cyclea peltata leaf powder and Lactobacillus plantarum.

Studies show that the extensive use of chemical shampoos has a negative impact on health. Given the recent trends, the use of herbal shampoos is gaining importance. Cyclea peltata is a common plant in Kerala's coastal region that has traditionally been used to aid in wound healing, allergy relief, and hair and scalp improvement. Greenly produced silver nanoparticles made from plant sources have a wide range of medical applications. The main objective is to optimize the base of the shampoo with better solid content by OFAT studies and characterize the silver nanoparticles synthesized using post optimized shampoo base. Cyclea peltata leaves were fermented with Lactobacillus plantarum for the shampoo formulation, substituting the chemical basis gelatin with an herbal fermented foundation. Silver nanoparticles combined with an herbal formulation should be as safe as herbal shampoo while also being as effective as chemical shampoo. Variation of concentration of Cyclea peltata leaf powder, variation of sucrose concentration, variation of concentration of yeast extract, variation of L.plantarum inoculum, variation of temperature, variation of agitation speed, and variation of time were all studied using the OFAT (One Factor At a Time) method. Silver nanoparticles synthesized using post optimized shampoo bases were also characterized by particle size, zeta potential, and FTIR analysis in order to better understand their properties. The results clearly indicated that all the six factors had a significant effect on the growth and production of EPS. The pH considered for the shampoo base is above 5so as to maintain the acidic mantle of the scalp. Green synthesized silver nanoparticles from post optimized shampoo base were obtained within 17th hour of incubation, with single surface plasmon resonance at 420nm. Nanoparticles showed a peak at -11.6mv of zeta potential which means that the particles are less agglomerative and stable. Similar groups were seen in ftir spectrum of fermented silver nanoparticles and the plant extract which confirmed the capping of nanoparticles with plant phytochemicals. The study successfully prepared and characterized green synthesized silver nanoparticles from post optimized shampoo base and also optimized the shampoo base based on the EPS production. Characterization of the silver nanoparticles found that the nanoparticles synthesized were stable, less agglomerative,and had several useful components present in it.

Ultrasonic green synthesis of different nickel nanoparticles and their application in Cr(VI) removal studies

In the recent work, synthesis of nanoparticles (NPs) was carried out by using leaves extract of Polyalthia longifolia and Ficus religiosa separately. Fourier transform infrared spectroscopy illustrated the dominant functional groups in leaves extract and prepared nanoparticles. A single surface plasmon resonance peak is obtained in both cases. SEM revealed that both the synthesized nanoparticles were spherical in shape. Average particle size of NiNPs using extract of Polyalthia longifolia and Ficus religiosa was found to be 42.21 nm and 43.178 nm. Different factors were optimized on comparative basis for removal studies of hexavalent chromium. Optimum response for both the nanoparticles is observed at 25 °C with 10 mg/L of Cr (VI) solution at adsorbent dosage value of 10 mg under acidic conditions (4 pH). In regeneration studies, maximum desorption for Polyalthia longifolia (88.16%) and Ficus religiosa (87.84%) leaves extract based nanoparticles was observed with 0.1 M HCl.

Large spectral shift of plasmon resonances in Au–Cu alloy nanoparticles through anisotropy and interaction

Nowadays, alloy nanoparticles (NPs) consisting of noble metals find much importance due to their enhanced localized surface plasmon resonance (SPR) in the visible range. Besides the compositional changes, the SPR of alloy NPs independently can be tailored by changing the shape and interparticle separation. Here, we report the effects of shape and interaction parameters (β and K, respectively) on the plasmonic properties of Au–Cu alloy NPs considering Au concentrations in the range of 0.0–1.0 using a modified effective medium theory. There is always a single SPR for the alloys’ NPs. A large shift of this SPR peak from visible to infrared regions is seen with decrease or increase in the values of β or K. A linear variation of peak shift with 1/β and an exponential decay variation of peak shift with 1/K are observed. Although there is a small increase in the values of slopes (in the peak shift vs. 1/β curves) with increase in concentration of Au in the Au–Cu alloys, there is almost no change in the fitting parameter, τ of the exponential decay function (in the curves for peak shift vs. 1/K) for different sizes of NPs and concentration of Au or Cu in the alloys. This establishes the universal nature of the exponential decay behaviour. These observations are consistent with the data for elemental (Au and Cu) NPs. The correlations between (i) shape parameter, β and the aspect ratio, AR and (ii) interaction parameter, K with the interparticle separation, s are established as in case of elemental NPs. The study thus, verifies the model further and establishes universality of the applicability of the model.

Surface Lattice Resonances in Self-Assembled Gold Nanoparticle Arrays: Impact of Lattice Period, Structural Disorder, and Refractive Index on Resonance Quality.

Surface lattice resonances are optical resonances composed of hybridized plasmonic and diffractive modes. These collective resonances occur in periodic arrays of plasmonic nanoparticles with wavelength-scale interparticle distances. The appearance and strength of surface lattice resonances strongly depend on the single particle localized surface plasmon resonance and its spectral overlap with the diffractive modes of the array. Coupling to in-plane orders of diffraction is also strongly affected by the refractive index environment and its symmetry. In this work, we address the impact of the interparticle distance, the symmetry of the refractive index environment, and structural imperfections in self-assembled colloidal monolayers on the plasmonic-diffractive coupling. For this purpose, we prepared hexagonally ordered, nonclose packed monolayers of gold nanoparticles using a fast and efficient, interface-mediated, colloidal self-assembly approach. By tuning the thickness and deformability of the polymer shells, we were able to prepare monolayers with a broad range of interparticle distances. The optical properties of the samples were studied experimentally by UV-Vis spectroscopy and theoretically by finite difference time domain simulations. The measured and simulated spectra allow a comprehensive analysis of the details of electromagnetic coupling in periodic plasmonic arrays. In particular, we identify relevant criteria required for surface lattice resonances in the visible wavelength range with optimized quality factors in self-assembled monolayers.

How specific are the conformation-specific α-synuclein antibodies? Characterization and validation of 16 α-synuclein conformation-specific antibodies using well-characterized preparations of α-synuclein monomers, fibrils and oligomers with distinct structures and morphology

Increasing evidence suggests that alpha-synuclein (α-syn) oligomers are obligate intermediates in the pathway involved in α-syn fibrillization and Lewy body (LB) formation, and may also accumulate within LBs in Parkinson's disease (PD) and other synucleinopathies. Therefore, the development of tools and methods to detect and quantify α-syn oligomers has become increasingly crucial for mechanistic studies to understand their role in PD, and to develop new diagnostic methods and therapies for PD and other synucleinopathies. The majority of these tools and methods rely primarily on the use of aggregation state-specific or conformation-specific antibodies. Given the impact of the data and knowledge generated using these antibodies on shaping the foundation and directions of α-syn and PD research, it is crucial that these antibodies are thoroughly characterized, and their specificity or ability to capture diverse α-syn species is tested and validated. Herein, we describe an antibody characterization and validation pipeline that allows a systematic investigation of the specificity of α-syn antibodies using well-defined and well-characterized preparations of various α-syn species, including monomers, fibrils, and different oligomer preparations that are characterized by distinct morphological, chemical and secondary structure properties. This pipeline was used to characterize 18 α-syn antibodies, 16 of which have been reported as conformation- or oligomer-specific antibodies, using an array of techniques, including immunoblot analysis (slot blot and Western blot), a digital ELISA assay using single molecule array technology and surface plasmon resonance. Our results show that i) none of the antibodies tested are specific for one particular type of α-syn species, including monomers, oligomers or fibrils; ii) all antibodies that were reported to be oligomer-specific also recognized fibrillar α-syn; and iii) a few antibodies showed high specificity for oligomers and fibrils but did not bind to monomers. These findings suggest that the great majority of α-syn aggregate-specific antibodies do not differentiate between oligomers and fibrils, thus highlighting the importance of exercising caution when interpreting results obtained using these antibodies. Our results also underscore the critical importance of the characterization and validation of antibodies before their use in mechanistic studies and as diagnostic tools or therapeutic agents. This will not only improve the quality and reproducibility of research and reduce costs but will also reduce the number of therapeutic antibody failures in the clinic.

Non-functionalized Au nanoparticles can act as high-performing humidity sensor

We synthesized gold (Au) nanoparticles via a rapid chemical route by reducing chloroauric acid by trisodium citrate. TEM micrographs revealed that particles were spherical with well-defined lattice structures and most of them were within the size range of 8–12 nm. A single surface plasmon resonance peak observed at 525 nm indicated the uniformness of the spherical morphology of the particles. XRD analysis showed that the particles were well crystalline. An impedance-based humidity sensor device was fabricated for depositing these gold nanoparticles in their non-functionalized state and the sensor revealed fast response time of 54 s, high stability and repeatability, and an impressive average sensitivity of 7.57 MΩ/% RH within the humidity range of 10–95%. SEM micrographs revealed the presence of cracks on the film surface and our analysis of the sensing mechanism correlated the sensitivity and the surface cracks along with smaller particle sizes. Our results show that gold nanoparticles without further functionalization are able to perform as a well-performing humidity sensor.

Hybrid Tamm-surface plasmon polariton mode for highly sensitive detection of protein interactions.

The total internal reflection ellipsometry (TIRE) method was used for the excitation and study of the sensitivity properties of the hybrid Tamm plasmon polariton - surface plasmon polariton (TPP-SPP) and single surface plasmon resonance (SPR) modes of the GCSF receptor immobilization. Additionally, the optimized sensitivity of the hybrid TPP-SPP mode was investigated and compared with the single SPR mode when the BSA proteins formed a layer on the gold surface. The dispersion relations for the hybrid TPP-SPP and single SPR modes were used to explain the enhanced sensitivity of the ellipsometric parameters for the hybrid TPP-SPP mode over the conventional SPR. The SPP component (δΔh-SPP/δλ=53.9°/nm) of the hybrid TPP-SPP mode was about 6.4 times more sensitive than single SPR (δΔSPR/δλ=8.4°/nm) for the BSA protein layer on the gold film. It was found that the sensitivity of the hybrid plasmonic mode can be made controllable by using the strong coupling effect between the TPP and SPP components. The strong coupling regime reduces absorption and scattering losses of the metal for the SPP component in the hybrid TPP-SPP mode and, as a result, narrows the plasmonic resonance.

Reusable surface plasmon resonance biosensor chip for the detection of H1N1 influenza virus

We developed a reusable magnetic surface plasmon resonance (SPR) sensor chip for detecting various target molecules repeatedly in a conventional SPR system. Here, ferromagnetic patterns on a SPR sensor chip were utilized to trap a layer of magnetic particles, and they were utilized as a solid substrate for SPR sensing in a conventional SPR system. After a sensing experiment, the used magnetic particles were removed by external magnetic fields, and a new layer of magnetic particles was immobilized to the SPR sensor chip for additional sensing measurements. Since magnetic particles were trapped on the ferromagnetic patterns, we could use our reusable SPR chip for SPR sensing measurements in a traditional SPR system without any applied magnetic fields. Significantly, ferromagnetic patterns on the sensor chip surface deflected the strong external fields, so that the large aggregation of magnetic particles on the sensor surface was reduced. We demonstrated using a single reusable SPR sensor chip to measure the nucleoprotein (NP) of H1N1 influenza virus solution ranging repeatedly for more than 7 times without significant signal degradation. Also, different target molecules could be repeatedly measured in a single SPR chip. Since our reusable SPR sensor chip can be repeatedly used in a conventional SPR system without any chemical processes for refreshment, the cost for SPR sensing should be significantly reduced. In this case, our reusable SPR sensor chip can be a major breakthrough and can be used for versatile practical applications of SPR sensors.

Pulse laser ablated growth of Au-Ag nanocolloids: Basic insight on physiochemical attributes

Despite considerable research the evidence around the wide applications in the nanomedicine and nanophotonic area of gold-silver (Au–Ag) nanocolloids remains equivocal and under exploration. Due to their physical properties, enhanced permeability, high fluorescent, surface area to volume ratio, retention effect, localized surface plasmon resonance (LSPR) and controlled perfusion of drugs, made Au–Ag nanoparticles is over interested. Hence, we produced Au–Ag nanocolloids using nanosecond pulse laser ablation in liquid (NPLAL) technique. Targets of Au and Ag were submerged individually inside the cubic vessel fulfilled by 8 mL of glycol liquid media and vertically ablated with different pulse laser ablation (PLA) energy (50, 100, 150 and 200 mJ). The influence of the PLA energy (at fundamental wavelength 1064 nm) on the optical properties, morphology, particle size distribution, and chemical structure of the obtained colloidal Au–Au NPs was established. UV-Vis and FTIR spectrophotometers have been utilized to determine the absorbance characteristics and chemical functional groups of Au–Ag nanostructures, respectively. The attained of Au-Ag nanostructure exhibits a single-surface plasmon resonance (SPR) band, positioned between SPR bands of the monometallic and a surface bonding functional group (e.g. carboxyl or hydroxy groups). The proposed technique can be a basis for the developing complex compositions/colloids with unique and optimal physical properties may use for developing future nanomedicinal and nanophotonics.

Nanoparticles Enhanced Self-driven Microfludic Biosensor.

C-reactive protein (CRP) plays an important role in inflammation detection and disease monitoring. The optical biosensor is a highly sensitive and easy detection tool. The microfluidic self-driving optical sensors were fabricated with transparent glass material and used for the enhanced surface plasmon resonance (SPR) optical detection of the model protein CRP using Au nanoparticles (AuNPs) and a sandwich immune reaction. The 3D design of the chip was devised to improve the optical coupling efficiency and enable integration with a microfluidic control and rapid detection. The array of pre-fixed antibody modified by Au nanoparticles was used to achieve rapid antigen capture and improve the optical sensitivity. The Au nanoparticle amplification approach was introduced for the SPR detection of a target protein. CRP was used as a model target protein as part of a sandwich assay. The use of Au NP measurements to detect the target signal is a threefold improvement compared to single SPR detection methods.