Gap-enhanced Raman tags (GERTs) represent an innovative optical probe designed based on surface-enhanced Raman scattering (SERS). SERS is a highly sensitive spectroscopic technique used to detect molecular vibrational and transitional information. In the context of SERS, the interaction between molecules and metallic nanostructures, such as Au or Ag nanoparticles, leads to a significant enhancement of Raman scattering signals-a phenomenon capable of amplifying molecular Raman scattering signals by over 10 orders of magnitude. By embedding Raman reporter molecules inside the internal plasmonic metallic nano-junction, GERTs exhibit extraordinary detection sensitivity down to the single-particle detection level; coupled with their ability to provide high-resolution molecular features, GERTs have found extensive applications across a multitude of fields. In this article, we provide a introduction to the preparation and optical properties of GERTs, with the goal of realizing their use in practical applications. At the same time, we provide a review of the pioneering use of GERTs as physically unclonable tags, along with their recent advances in biomedical imaging and integrated diagnostics. Finally, we provide a assessment of the challenges GERTs face in real-world application scenarios, providing critical reference points for advancing the clinical translation of GERTs technology. Looking ahead, with further research and development, the novel, stable and super-bright GERTs probes are poised to become a central analytical tool, offering even richer opportunities for practical applications and scientific research.

Spectral coding refers to the means of combining the limited spectral signal output to obtain more spectral signal output, which meets the requirements of high-throughput biological detection and imaging and high-capacity information storage. The output of signal usually used for spectral coding includes fluorescence spectrum, Raman spectrum and reflection spectrum. Among them, the Raman spectra have great potential in the field of spectral coding due to the narrow band width and difficult overlap, especially the three-bond Raman spectra in the bio-silent zone with sharp, specific band and no background interference. In this paper, the types and coding methods of Raman spectral coding are reviewed, and the applications of Raman spectral coding in biomedical detection, imaging and information security are also introduced.

Surface-enhanced fluorescence (SEF) is a cross-space interaction that is affected by the distance between fluorescent molecules and metal nanoparticles. The core-shell structure has become a research topic that has attracted much attention in recent years because of its simple preparation method and easy adjustment of shell thickness. This review introduces several core-shell structures widely used in the study of surface-enhanced fluorescence and their research progress at home and abroad, mainly including the shell structure with metal nanoparticles as the core, the shell structure with metal nanoparticles as the shell, and some other core-shell structures. Then, combined with the research status, the future development of the core-shell structure is prospected.

In recent years, with the rapid development of nanotechnology, surface-enhanced Raman scattering (SERS) technology has been widely applied in various fields such as physical chemistry, materials science, surface science, and biology. Based on zinc oxide/metal composite SERS substrates, which have high Raman enhancement performance and excellent green cycling performance, they are gradually becoming one of the research hotspots in SERS technology. This article reviews the research progress on the mechanism, preparation, regulation, and application of zinc oxide composite SERS substrates, and analyzes the relevant research trends, thereby providing important references for the development of high-performance recyclable SERS substrates and the study of enhancement mechanisms.

In order to focus coherent light and image through scattering media in noisy environment, a score assessment algorithm is proposed to optimize the phase distribution of the incident wavefront. The basic idea of the score assessment algorithm is to mark the phase value according to the target intensity in the optimization process. Binary phase optimization is exploited to increase the speed of the program, which can be applied to dynamic scattering media. Compared with the ant colony algorithm, it is found that the score assessment algorithm can achieve a focus under strong disturbance, while the ant colony algorithm is invalid in noisy environment. In experiments, it is found that the intensity of the target signal is enhanced 71.4 times over the average speckle intensity using the score assessment algorithm. Therefore, the score assessment algorithm should be considered firstly in the application of biological imaging, photoelectric detection and other fields.

Fiber-optics sensors offer advantages such as compact size, high flexibility, immunity to electromagnetic interference, lightweight, and suitability for remote signal transmission. These advantages make them well-suited for combining with excellent Surface-enhanced Raman Scattering (SERS) technology to create fiber-optic SERS sensors, widely applied in label-free chemical and biological sensing fields. Compared to other optical sensing techniques, fiber-optic SERS sensors inherit all the advantages of traditional SERS technology while offering multiplexing capabilities and the ability to continuously and dynamically monitor in special environments. This review primarily covers the development of the structure of fiber-optic SERS sensors and their applications. First, it explores the development and necessity of fiber-optic SERS sensors. Second, it introduces common types of fiber-optic SERS sensors and their fabrication methods. Finally, it briefly outlines the extensive applications and prospects of fiber-optic SERS sensors in various fields.

Interferon-γ (IFN-γ) is an important cytokine, which can be used as a biomarker for disease prevention, diagnosis, and prognosis detection in clinics. To achieve highly sensitive detection of IFN-γ, an aptasensor based on hybrid structure of antibodies and aptamer was developed, which involves two probes. Firstly, 4-Mercaptobenzoic acid (4-MBA) was embedded into Au-Ag Alloy nanoparticles, and then coupled with the aptamer as detection probes. Secondly, magnetic beads modified by antibodies were used as capture probes. When IFN-γ is present, IFN-γ can be captured by both aptamers and antibodies, forming a stable sandwich structure, and obtaining strong Raman signals. On the contrary, when there is not IFN-γ, weak Raman signals are obtained. We optimized the relevant parameters such as volume of 4-MBA and antibody, concentration of aptamer. The experimental results show that this method has high sensitivity and repeatability, with a limit of detection (LOD) of 0.25 pg/mL in PBS. Due to the high recovery rate of this method in serum ranging from 98.7% to 108%, we believe that this aptasensor can achieve the fast and accurate detection of interferon-γ in complex serum environments to meet clinical needs.

SERS technique has become one of the powerful tools for monitoring surface/interface reaction processes due to its extremely high surface sensitivity and selectivity. The control of photocatalytic performance is critically based on the well understanding of the reaction process at molecular level. The in-situ monitoring of photocatalytic processes can be realized by the integration of SERS substrate and photocatalyst to provide the interfacial information. In this paper, bifunctional Cu2O-Au composites with both catalytic and SERS activities were synthesized, the SERS enhancement and photocatalytic degradation of methyl orange (MO) were studied as well as the dynamic processes of photocatalytic degradation of MO. The results demonstrate that bifunctional Cu2O-Au composites is beneficial to effectively integrate SERS effect and photocatalytic performance, and the in-situ monitoring of photocatalytic degradation at the Cu2O-Au interfaces was achieved accordingly. The introduction of Au nanoparticles enhanced the SERS effect by two orders of magnitude and double the catalytic degradation performance of Cu2O. In situ monitoring results of MO photocatalytic degradation processes revealed that N=N bond was the most easy to break, and C=C bond was the most difficult to break. The sequence of chemical bond break is N=N > Ph1-N=,= N-Ph2, and Ph1-N=, C-N > Ph-N.

In the present study, a solvent-thermal method was used to successfully synthesise hydroxylated nickel chloride with a fullerene-like structure. This synthesized material was implemented as a substrate for surface-enhanced Raman scattering (SERS), and crystal violet (CV) served as a probe molecule to evaluate the SERS performance under an excitation wavelength of 532 nm. The results obtained demonstrate the remarkable sensitivity of the substrate in detecting crystal violet, even at the significantly low concentration of 10-8 mol/L.Furthermore, by introducing sulphur and carefully adjusting the concentration ratios of the reactants, a sulphur-hydroxylated nickel chloride compound was synthesised while retaining its characteristic fullerene-like structure. This incorporation of sulfur into the substrate effectively enhanced the Raman scattering effect, thereby significantly improving its sensitivity for the detection of trace amounts of crystal violet (CV) at an unprecedented concentration as low as 10-11 mol/L, resulting in an improvement of three orders of magnitude. In addition, an examination of the SERS signal from 5000 data points revealed a standard deviation (RSD) of 4.4% for the sulphur-hydroxylated nickel chloride substrate, indicating exceptional reproducibility and uniformity.The morphological and structural characterisation of both hydroxylated and sulphur-hydroxylated nickel chloride was carried out using various analytical techniques such as scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD).

In this paper, the centimeter-scale uniform silver nanoparticles (AgNPs) arrays with controllable sizes are prepared by using anodic aluminum oxide template-assisted vacuum thermal evaporation technology. Then, the monolayer MoS2/AgNPs array hybrid structures are obtained by wet transfer method. The surface-enhanced fluorescence (SEF) properties of the hybrid structure are systematically investigated. We find that the fabricated AgNPs arrays could be used as efficient SEF substrates to enhance the fluorescence intensity of monolayer MoS2. Meanwhile, the fluorescence intensity of monolayer MoS2 can been further improved with temperature decreasing. This study may provide a basis for the application of MoS2 in the field of optoelectronic integration.

The mural paintings in the Main Hall of Fengguo Temple are exquisite and unique, with immense historic value and artistic value. However, over time, the murals have suffered from various degrees of damage. One prominent issue is the presence of different types of attachments on the mural surfaces. A condition assessment of the current state of the four types of attachments on the mural surface reveals variations in their distribution. X-ray diffraction and infrared spectrometer are used to analyze the composition of four types of attachments. The results indicate that the four types of attachments are calcium carbonate, unsaturated polyester lacquer, paper fiber, and polyvinyl alcohol formaldehyde and polyvinyl acetate. Environmental monitoring and comprehensive analysis of relevant historic documentation suggest that the main cause of these attachments is closely related to historic conservation. The objective of this study is to systematically reveal the characteristics of the attachments covering the mural surfaces in Fengguo Temple through diagnostic investigation, component analysis, and causation analysis. This research aims to provide a theoretical foundation for the cleaning of the attachments and the conservation of the mural paintings.