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The development of sensitive and specific exosome detection tools is essential because they are believed to provide specific information that is important for early detection, screening, diagnosis, and monitoring of cancer. Among the many detection tools, surface-plasmon resonance (SPR) biosensors are analytical devices that offer advantages in sensitivity and detection speed, thereby making the sample-analysis process faster and more accurate. In addition, the penetration depth of the SPR biosensor, which is <300 nm, is comparable to the size of the exosome, making the SPR biosensor ideal for use in exosome research. On the other hand, another type of nanoplasmonic sensor, namely a localized surface-plasmon resonance (LSPR) biosensor, has a shorter penetration depth of around 6 nm. Structural optimization through the addition of supporting layers and gap control between particles is needed to strengthen the surface-plasmon field. This paper summarizes the progress of the development of SPR and LSPR biosensors for detecting exosomes. Techniques in signal amplification from two sensors will be discussed. There are three main parts to this paper. The first two parts will focus on reviewing the working principles of each sensor and introducing several methods that can be used to isolate exosomes. This article will close by explaining the various sensor systems that have been developed and the optimizations carried out to obtain sensors with better performance. To illustrate the performance improvements in each sensor system discussed, the parameters highlighted include the detection limit, dynamic range, and sensitivity. [ABSTRACT FROM AUTHOR]

The development of sensitive and specific exosome detection tools is essential because they are believed to provide specific information that is important for early detection, screening, diagnosis, and monitoring of cancer. Among the many detection tools, surface-plasmon resonance (SPR) biosensors are analytical devices that offer advantages in sensitivity and detection speed, thereby making the sample-analysis process faster and more accurate. In addition, the penetration depth of the SPR biosensor, which is

In recent years, the D-shaped photonic-crystal-fiber localized surface-plasmon-resonance (LSPR) sensor is a research hot spot, especially for liquid refractive-index sensors. In this paper, we propose a doublemeasurement-accuracy LSPR sensor. In numerical simulations, when the refractive index of the analyte changes from 1.33 to 1.4, we obtain the maximum sensitivity equal to 15,500 nm/RIU. At refractive index values of the analyte equal to 1.38 and 1.39, there are two resonance peaks, and the wavelength sensitivity of the second peak is 25,000 nm/RIU, which has a good prospect in specific liquid detection. [ABSTRACT FROM AUTHOR]

Surface-enhanced Raman spectroscopy (SERS) is a unique technique that allows us to detect samples in trace quantities. The spectral intensities of the characteristic Raman peaks of the analyte molecule are enhanced manifold in the presence of noble metal nanoparticles (NPs). The existence of NPs is necessary to couple the incident electromagnetic field with NPs through the localized surface plasmon resonance phenomenon, which primarily contributes to the enhancement of an SERS signal. The present work demonstrates the working of a paper-based SERS substrate to detect and quantify two pharmaceutical drugsâ€"paracetamol and aspirinâ€"in water. The proposed SERS substrate was obtained by drop-casting silver NPs over printing grade 100 grams per square meter (GSM) paper. 100 GSM denotes the class of paper where 100 grams of raw materials (cellulose) is used per square meter to manufacture the paper. The performance of the designed SERS substrate was initially evaluated with two Raman active samplesâ€"malachite green and rhodamine-6G. The applicability of the proposed SERS substrate was evaluated further through monitoring the Raman spectra of the two aforementioned pharmaceutical drugs in different field-collected water samples, thus establishing the reliability of the scheme in a real field environment. [ABSTRACT FROM AUTHOR]

Abstract A tunable blue random laser based on solid waveguide gain films with silver nanoparticles (NPs) and SiO 2 NPs is demonstrated. Localized surface plasmon resonance (LSPR) property and multiple scattering are proven playing an important role simultaneously. The tunability of the blue random laser is realized by simply roughing and changing the thickness of the solid waveguide gain films. To our knowledge, it is the first time using this method to achieve a wide wavelength tuning range of ∼24 nm. Highlights • Tunable blue random laser based on solid waveguide gain films. • Plasmonics and scatterers are playing an important role. • Ag nanoparticles with diameters of 4.8 nm are harmful to random lasing. • Emission wavelength can be tuned with changing the thickness of gain films. [ABSTRACT FROM AUTHOR]

Random multimode lasers are achieved in 4(dicyanomethy-lene)−2- tert-butyl-6(1,1,7,7-tetramethyljulolidyl-9-enyl)4H-pyran (DCJTB) doped Polystrene (PS) thin films by introducing silver nanoparticles (Ag NPs) as scatterers. Ag NPs were prepared by polymer protection method. By optimizing the concentration of reactant of AgNO 3 and the ratio of Ag NPs to DCJTB, the devices emit a resonance multimode peak at a center wavelength of 625 nm and the threshold excitation intensity is as low as 0.0031 mJ/pulse. It can be seen that the microscopic random resonance cavities can be formed by multiple scattering of Ag NPs which supply the localized surface-plasmon resonance (LSPR) coupling with the lasing emission to enhance the lasing efficiency. Our results demonstrate that Ag NPs are promising candidate as alternative sources of coherent light emission to realize low-threshold organic random lasers. [ABSTRACT FROM AUTHOR]

Random lasing threshold reduction and emission enhancement were reported from a suspension of Ag nanoparticles (NPs) in a laser dye doped polymer film. To evaluate the effect of the localized surface plasmon resonance (LSPR) of metal NPs on random lasing from lasing dye, we carry out a comparative study of the random lasing performance of the Ag NPs and SiO 2 NPs scattered dye doped polymer films. Random lasing emission was obtained from Ag NPs and SiO 2 NPs scattered dye doped polymer films. The threshold was dramatically reduced from 0.01 to 0.003 mJ/pulse as Ag NPs was used as scatters instead of SiO 2 NPs. Theoretical simulation indicates that a large localized electric field is built near the Ag particle surface which enhances the absorption of excitation light. Furthermore, excellent overlap of the plasmonic resonance of Ag NPs with the absorption and photoluminescence spectrum of the dye molecules promotes more dye molecules excited simultaneously to the higher energy levels and leads to more effective random lasing performance. [ABSTRACT FROM AUTHOR]

We reported on the enhanced random lasing from organic dyes doped with silver nanoparticles (Ag NPs), the sizes of Ag NPs ranged from 8 nm to 250 nm. The effects of different sizes of Ag NPs on the lasing properties were studied. We found a strong dependence of the random lasing properties on the size of the Ag NPs, and the lowest threshold was achieved by the introduction of Ag NPs with the diameter of 150 nm. By studying the enhanced localized electromagnetic (EM) field due to localized surface-plasmon resonance and the scattering effect of Ag NPs in experiment and Mie theory, we found that the enhanced localized EM field plays a major role on enhanced lasing of organic dyes for the small Ag NPs (diameter < 50 nm); and the scattering effect is the dominant underlying mechanism for random lasing for the large Ag NPs (diameter ≥ 100 nm), which also suggest that the lowest threshold and strongest lasing are dominated by the photon scattering. [ABSTRACT FROM AUTHOR]

Shell-isolated nanoparticle (NP)-enhanced Raman spectroscopy (SHINERS) has expanded the versatility of surface-enhanced Raman scattering (SERS) and can be applied to virtually any substrate type and morphology. Surface-plasmon resonance (SPR) can enhance fluorescence through an electromagnetic field in a similar way to SERS, which is called surface-enhanced fluorescence (SEF) or metal-enhanced fluorescence (MEF). The SERS-SEF dual-mode method can greatly improve the accuracy and the sensitivity of detection in applications. In this review, we introduce extension of SHINERS to shell-isolated NP-enhanced fluorescence (SHINEF) and application of the SERS-fluorescence dual-mode technique, taking advantage of SERS and fluorescence. We first introduce SHINERS and its applications, and then move on to the applications of SHINERS in SEF. Finally, we introduce application of the SERS-fluorescence dual mode to biodetection and bioimaging. [ABSTRACT FROM AUTHOR]

Abstract: To detect volatile organic compounds (VOCs), optical sensors based on the localized surface-plasmon resonance (LSPR) are widely used because they are simple and inexpensive to fabricate. Although LSPR spectroscopy has been generally applied to biological molecules such as proteins and DNA, small molecular sensing has been difficult because of the very small changes induced in the refractive index. We describe a LSPR gas sensor with high and wide range sensitivity. These characteristics are obtained from the improved peak shift that results from using an Au-dot pattern coated with a porous silica film. The 400-nm-diameter, 800-nm-wide Au dots were patterned by electron beam lithography (EBL) on a quartz glass substrate. The LSPR peak of the isolated Au-dot pattern occurs at 1230nm in the near isolated area bringing enough refractive index changes. In addition, coating the Au-dot pattern with a thin porous silica film increases the adsorption of VOCs, thereby increasing the refractive-index change. The response of the sensor to VOC vapors was measured in a dynamic-flow system. The relative intensity decreases with toluene vapor exposure but completely recovers to the initial baseline after exposure to clean air. The real-time response allows detection of toluene vapors with concentrations ranging from 1 to 26,000ppm, and the limit of detection for toluene is calculated to be 0.4ppm. Eighteen VOC vapors were tested and each type exhibited different calibration curves, but these differences depend on the adsorption characteristics of porous silica rather than on the refractive index of the VOCs. [Copyright &y& Elsevier]

This report presents a facile microfabrication-compatible approach to fabricate a large area of plasmonic nano-pyramid array-based antennas and demonstrates effective light management by tailoring the architecture. First, a long-range ordered gold nano-pyramid array is fabricated, which exhibits strong light scattering. The maximum electric field enhancement (| E |/| E 0 |) of 271 is achieved at the corner but decays rapidly away from the pyramid bottom. After the gold nanopyramid array is coupled to a gold film, strong light scattering is converted into strong light absorption due to the excitation of a spectrally tunable plasmonic gap mode, where an intense electric field enhancement of 233 and a strong magnetic field enhancement (| H |/| H 0 |) of 25 are simultaneously excited for a 10 nm silica gap. The electric field decays much slower away from the pyramid bottom while the magnetic field keeps almost constant. In addition, both experiments and finite-difference time-domain (FDTD) simulation have confirmed that strong plasmon-exciton coupling between the plasmonic gap mode and the J-aggregates can take place when the quantum emitters such as J-aggregates are embedded in the gap, creating plexcitons. This can overcome the problems of high energy loss and weak nonlinearity, which are typically associated with surface plasmon polariton (SPP) supported on plasmonic metallic nanostructures. The coherent plasmon-exciton coupling (plexciton) generated by the film-coupled nano-pyramid nanostructure is expected to find promising applications in light-emitting devices, photodetectors, photovoltaics and photoelectrochemical cells., Competing Interests: The authors declare no competing financial interest.