Gate-voltage control of angular and spatial shifts for a dielectric slab containing graphene

By theoretically considering a dielectric slab containing graphene, we investigate the effect of the graphene layer on the angular Goos-Hänchen (AGH) shifts and the transverse angular and spatial shifts from the spin-Hall effect of light (SHEL) for the reflection of a light beam. Through manipulating the voltage applied to graphene via an exterior gate, it was found that near the transmission resonance of the slab containing graphene, the giant and tunable AGH shifts and transverse shifts (TS) for both s-polarized and p-polarized waves are present. We also find that near the normal incident angle, the giant and tunable TS from SHEL for both s-polarized and p-polarized waves can occur on the interface containing graphene. It is expected that these phenomena can result in significant interesting and novel applications of graphene in all kinds of optical devices, and more

An Endoscope-like SERS Probe Based on the Focusing Effect of Silica Nanospheres for Tyrosine and Urea Detection in Sweat

In this work, we developed a new type of SERS probe, which was composed of glass-SiO2-Au@MBN@Ag nanoparticles (NPs) three-dimensional Surface-enhanced Raman spectroscopy (SERS) substrate. When the laser passed through the quartz glass sheet, on the one hand, the SiO2 NPs supporting the Au@MBN@Ag NPs increase the roughness of the substrate surface, resulting in a large number of hot spots among nanoparticles. On the other hand, based on the focusing effect of silicon dioxide nanospheres, the laser can better focus on the surface of nanoparticles in the inverted SERS probe, thus showing better SERS enhancement. Furthermore, the Au@MBN@Ag NPs core-shell structure was used with 4-mercaptobenzoonitrile (MBN) as an internal standard molecule, and the quantitative determination of tyrosine and urea was realized by internal standard correction method. The standard working curves of the two had good linear correlation with R2 above 0.9555. The detection limits of tyrosine and urea were in the range of 2.85 × 10−10 M~7.54 × 10−6 M, which confirms that this design can be used for quantitative and specific detection of biological molecules, demonstrating great practical significance for the research of diseases such as skin lesions and endocrine disorders

Study on Fracture Healing with Small-Splint-Fixation Therapy by Near-Infrared Raman Spectroscopy

In this study, near-infrared (NIR) Raman spectroscopy was explored to assess the incorporation of calcium hydroxyapatite (CHA ∼960 cm −1 ) and other biochemical substances during the recovery of rabbits with complete radial fractures treated with or without small splints. 24 rabbits were randomy divided into two groups, one treated with small-splint-�xation therapy and the other without any intervention. e rabbits were sacri�ced at 7, 15, 23, and 30 days a�er surgery, and the surface layers of the calluses in the fracture healing site from control and treated groups were routinely prepared for Raman spectroscopy. e prominent Raman bands were observed, including minerals at 430, 590, 960, 1003, and 1071 cm −1 , protein at 856, 876, 1246, and 1667 cm −1 , and lipid at 1767 cm −1 . e carbonate-to-phosphate ratio (CO 3 to 1 PO 4 ) and the mineral-to-matrix ratio ( 1 PO 4 to amide I) were calculated from these normalized Raman bands. Comparison of the 1 PO 4 -to-amide I ratio for the control group with that of the treated group probably indicated that the small-splint-�xation therapy could be useful for the gradual mineralization of the collagen matrix during fracture healing

Diazotization-Coupling Reaction-Based Determination of Tyrosine in Urine Using Ag Nanocubes by Surface-Enhanced Raman Spectroscopy

A novel, simple, and highly sensitive method was developed to detect the concentration of tyrosine-derived azo dye indirectly using silver nanocubes (AgNCs) as a substrate on a super-hydrophobic silver film by surface-enhanced Raman spectroscopy (SERS). Diazotization-coupling reaction occurred between diazonium ions and the phenolic tyrosine, resulting in three new typical peaks in the SERS spectrum of the azo dye that was formed on the AgNCs, indicating strong SERS activity. Subsequently, the limit of detection of this approach was as low as 10−12 M for tyrosine. Moreover, the SERS intensities of the three typical SERS signals of the analyte were linearly correlated with the logarithm of concentration of the Tyrosine. The proposed method shows great potential for tyrosine detection in the urine samples of normal humans

Metabolic characteristics revealing cell differentiation of nasopharyngeal carcinoma by combining NMR spectroscopy with Raman spectroscopy

Abstract Background The staging system of nasopharyngeal carcinoma (NPC) has close relationship with the degree of cell differentiation, but most NPC patients remain undiagnosed until advanced phases. Novel metabolic markers need to be characterized to support diagnose at an early stage. Methods Metabolic characteristics of nasopharyngeal normal cell NP69 and two types of NPC cells, including CNE1 and CNE2 associated with high and low differentiation degrees were studied by combining 1H NMR spectroscopy with Raman spectroscopy. Statistical methods were also utilized to determine potential characteristic metabolites for monitoring differentiation progression. Results Metabolic profiles of NPC cells were significantly different according to differentiation degrees. Various characteristic metabolites responsible for different differentiated NPC cells were identified, and then disordered metabolic pathways were combed according to these metabolites. We found disordered pathways mainly included amino acids metabolisms like essential amino acids metabolisms, as well as altered lipid metabolism and TCA cycle, and abnormal energy metabolism. Thus our results provide evidence about close relationship between differentiation degrees of NPC cells and the levels of intracellular metabolites. Moreover, Raman spectrum analysis also provided complementary and confirmatory information about intracellular components in single living cells. Eight pathways were verified to that in NMR analysis, including amino acids metabolisms, inositol phosphate metabolism, and purine metabolism. Conclusions Methodology of NMR-based metabolomics combining with Raman spectroscopy could be powerful and straightforward to reveal cell differentiation development and meanwhile lay the basis for experimental and clinical practice to monitor disease progression and therapeutic evaluation

Metabolic characteristics revealing cell differentiation of nasopharyngeal carcinoma by combining NMR spectroscopy with Raman spectroscopy

Abstract Background The staging system of nasopharyngeal carcinoma (NPC) has close relationship with the degree of cell differentiation, but most NPC patients remain undiagnosed until advanced phases. Novel metabolic markers need to be characterized to support diagnose at an early stage. Methods Metabolic characteristics of nasopharyngeal normal cell NP69 and two types of NPC cells, including CNE1 and CNE2 associated with high and low differentiation degrees were studied by combining 1H NMR spectroscopy with Raman spectroscopy. Statistical methods were also utilized to determine potential characteristic metabolites for monitoring differentiation progression. Results Metabolic profiles of NPC cells were significantly different according to differentiation degrees. Various characteristic metabolites responsible for different differentiated NPC cells were identified, and then disordered metabolic pathways were combed according to these metabolites. We found disordered pathways mainly included amino acids metabolisms like essential amino acids metabolisms, as well as altered lipid metabolism and TCA cycle, and abnormal energy metabolism. Thus our results provide evidence about close relationship between differentiation degrees of NPC cells and the levels of intracellular metabolites. Moreover, Raman spectrum analysis also provided complementary and confirmatory information about intracellular components in single living cells. Eight pathways were verified to that in NMR analysis, including amino acids metabolisms, inositol phosphate metabolism, and purine metabolism. Conclusions Methodology of NMR-based metabolomics combining with Raman spectroscopy could be powerful and straightforward to reveal cell differentiation development and meanwhile lay the basis for experimental and clinical practice to monitor disease progression and therapeutic evaluation

Fabrication and Characterization of a Highly-Sensitive Surface-Enhanced Raman Scattering Nanosensor for Detecting Glucose in Urine

Herein we utilized coordination interactions to prepare a novel core-shell plasmonic nanosensor for the detection of glucose. Specifically, Au nanoparticles (NPs) were strongly linked with Ag+ ions to form a sacrificial Ag shell by using 4-aminothiophenol (4-PATP) as a mediator, which served as an internal standard to decrease the influence of the surrounding on the detection. The resultant Au-PATP-Ag core-shell systems were characterized by UV-vis spectroscopy, transmission electron microscopy, and surface-enhanced Raman scattering (SERS) techniques. Experiments performed with R6G (rhodamine 6G) and CV (crystal violet) as Raman reporters demonstrated that the Au@Ag nanostructure amplified SERS signals obviously. Subsequently, the Au@Ag NPs were decorated with 4-mercaptophenylboronic acid (4-MPBA) to specifically recognize glucose by esterification, and a detection limit as low as 10−4 M was achieved. Notably, an enhanced linearity for the quantitative detection of glucose (R2 = 0.995) was obtained after the normalization of the spectral peaks using 4-PATP as the internal standard. Finally, the practical applicability of the developed sensing platform was demonstrated by the detection of glucose in urine with acceptable specificity

Ag-Coated Cellulose Fibers as Surface-Enhanced Raman Scattering Substrates for Adsorptive Detection of Malachite Green

Surface-enhanced Raman scattering (SERS) is a sensitive technique for the detection of low concentration analytes. In this study, we used cellulose fibers (CF) as the templates for the loading of silver nanoparticles (Ag NPs), and the obtained CF-Ag was applied in the detection of R6G and Malachite Green (MG) by surface-enhanced Raman scattering. The adsorption technique was employed in the sample preparation, and the optimal detecting status was identified in the dynamic range (sample status ranging from wet to dry) for different concentration of analytes. In comparison to Ag NPs, CF-Ag showed enhanced performance for adsorptive detection of Malachite Green, and the limit of detection was 5 × 10−12 M