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Surface-enhanced Raman spectroscopy (SERS) has been widely investigated and employed as a powerful optical analytical technique providing fingerprint vibrational information of molecules with high sensitivity and resolution. In addition to metallic nanostructure, dielectric micro-/nano-structures with extraordinary optical manipulation properties have demonstrated capability in enhanced Raman scattering with ultralow energy losses. Here we report a facile cascaded structure composed of a large microsphere (LMS) and a small microsphere array with Ag nanoparticles as a novel hybrid SERS substrate, for the first time. The cascaded microsphere-coupled SERS substrate provides a platform to increase the molecular concentration, boost the intensity of localized excitation light, and direct the far-field emission, for giant Raman enhancement. It demonstrates the maximum enhancement factor of Raman intensity greater than 108 for the limit of detection down to 10−11 M of 4-nitrothiphenol molecules in aqueous solution. The present work inspires a novel strategy to fabricate cascaded dielectric/metallic micro-/nano-structures superior to traditional SERS substrates towards practical applications in cost-effective and ultrahigh-sensitive trace-detection.

Surface‐enhanced Raman spectroscopy (SERS) is a powerful tool for nondestructive and ultrasensitive optical trace‐detection. However, the sophisticated fabrication processes and performance degradation on flexible substrates block SERS for practical uses. Here, we report a facile flexible microsphere‐coupled SERS (McSERS) substrate composed of a dielectric microsphere cavity array (MCA) and random gold nanoparticles (AuNPs) capping on a polydimethylsiloxane (PDMS) film (MCA/AuNPs/PDMS) for giant Raman enhancement. The random distribution of AuNPs provides a hydrophilic surface against to the coffee‐ring effect for uniform localized surface plasmon resonance (LSPR) response. The MCA capped on the AuNPs boosts the Raman intensity via the multiple optical manipulation processes, in which the photonic nanojet (PNJ) confines the excitation intensity near the AuNPs, whispering‐gallery mode (WGM) facilitates the energy transfer from microsphere cavities to AuNP gaps for LSPR boosting, and directional antenna effect converts near‐field Raman signals into far‐field with a small divergence. Therefore, the Raman scattering is dramatically improved with the enhancement factor (EF) to 107 for the limit of detection (LoD) of 4‐nitrobenzenethiol (4‐NBT) molecules down to 0.1 nM, two orders of magnitude higher via MCA coupling. Moreover, the flexible McSERS substrate exhibits outstanding durability and compatibility as an ultrasensitive Raman test strip, by which the thiram concentration is detectable down to 2.42 ng/cm2 on apple peels. The present work provides a facile strategy to fabricate SERS substrates with high flexibility for optical trace‐detection in real‐world applications.

Background: Knee osteoarthritis (KOA), a chronic degenerative disease, is mainly characterized by destruction of articular cartilage and inflammatory reactions. At present, there is a lack of economical and effective clinical treatment. Zhuifeng Tougu (ZFTG) capsules have been clinically approved for treatment of OA as they relieve joint pain and inflammatory manifestations. However, the mechanism of ZFTG in KOA remains unknown.Purpose: This study aimed to investigate the effect of ZFTG on the TLR4/ MyD88/NF-κB signaling pathway and its therapeutic effect on rabbits with KOA. Study design:In vivo, we established a rabbit KOA model using the modified Videman method. In vitro, we treated chondrocytes with IL-1β to induce a proinflammatory phenotype and then intervened with different concentrations of ZFTG. Levels of IL-1β, IL-6, TNF-α, and IFN-γ were assessed with histological observations and ELISA data. The effect of ZFTG on the viability of chondrocytes was detected using a Cell Counting Kit-8 and flow cytometry. The protein and mRNA expressions of TLR2, TLR4, MyD88, and NF-κB were detected using Western blot and RT-qPCR and immunofluorescence observation of NF-κB p65 protein expression, respectively, to investigate the mechanism of ZFTG in inhibiting inflammatory injury of rabbit articular chondrocytes and alleviating cartilage degeneration.Results: The TLR4/MyD88/NF-κB signaling pathway in rabbits with KOA was inhibited, and the levels of IL-1β, IL-6, TNF-α, and IFN-γ in blood and cell were significantly downregulated, consistent with histological results. Both the protein and mRNA expressions of TLR2, TLR4, MyD88, NF-κB, and NF-κB p65 proteins in that nucleus decreased in the ZFTG groups. Moreover, ZFTG

We present the triangular lattice pattern with the invisible Kagome lattice in the dielectric barrier discharge system with two water electrodes for the first time. The spatio-temporal dynamics studied by an intensified charge-coupled device (ICCD) show that the complex pattern is composed of four different sublattices: Kagome lattice, halos, and big and small spots (B and S). The invisible Kagome lattice is similar to the dark discharge because of its spatio-temporal randomness. Based on the novel discharges (B and S) occurring at the falling edge of applied voltage, the dynamics of surface charges is investigated and demonstrated with a high speed video camera and photomultiplier tubes. Furthermore, the formation of restricted random structures is considered to be the effect of previous discharges which rearrange the surface charges.