17β-E2 is used in animal growth regulation and agricultural fertilizer, and even ng L-1 mass concentration levels can show biological effects. In this work, Ag NPs was used as surface-enhanced Raman spectroscopy (SERS) source and WS2 was synthesized by a simple method to provide a uniform distribution platform for Ag NPs. The MIP was the shell, which can selectively enrich the target molecule, pull the distance between the target molecule and SERS source, and protect Ag NPs. A cyclable SERS substrate with high sensitivity for detecting 17β-E2 in food was constructed. The optimized WS2/Ag@MIP as SERS substrate has the advantages of high Enhanced Factor (EF = 2.78 × 109), low detection limit (LOD = 0. 0958 pM), strong anti-interference ability, and good recycling performance. Moreover, the detection of 17β-E2 in real samples still has good accuracy. This work provides a new possibility for the trace detection of 17β-E2 in food.

Escherichia coli contamination in food and pharmaceutical preparations needs to be strictly controlled according to the regulations in many countries. However, rapid and sensitive E. coli detection is still a challenge. In this study, an aptamer-based surface-enhanced Raman spectroscopy (SERS) sandwich method was developed for the rapid and sensitive detection of E. coli using an aptamer-functionalized Au-Ag@Si triangular pyramid (TP) substrate. The Au-Ag@Si TP substrate was functionalized with E. coli aptamer to work as both the capture probe and SERS tag by integrating with Raman reporter (6-carboxy-X-rhodamine). The fabrication of the capture probe, SH-apt@Au-Ag@Si TP, was simple and rapid (20.5 h). This method could selectively and rapidly detect E. coli with a limit of detection of 2.8 CFU/mL within approximately 3 h. It was successfully applied to a traditional Chinese medicine preparation, Xinhuang tablets, with recoveries ranging from 90.19 % to 104.17 %. The results indicated that the developed method was simple and rapid, and it could be a promising alternative for the on-site detection of E. coli in pharmaceutical and food samples.

Nasopharyngeal cancer (NPC) is a malignant tumor with high prevalence in Southeast Asia and highly invasive and metastatic characteristics. Radiotherapy is the primary strategy for NPC treatment, however there is still lack of effect method for predicting the radioresistance that is the main reason for treatment failure. Herein, the molecular profiles of patient plasma from NPC with radiotherapy sensitivity and resistance groups as well as healthy group, respectively, were explored by label-free surface enhanced Raman spectroscopy (SERS) based on surface plasmon resonance for the first time. Especially, the components with different molecular weight sizes were analyzed via the separation process, helping to avoid the possible missing of diagnostic information due to the competitive adsorption. Following that, robust machine learning algorithm based on principal component analysis and linear discriminant analysis (PCA-LDA) was employed to extract the feature of blood-SERS data and establish an effective predictive model with the accuracy of 96.7% for identifying the radiotherapy resistance subjects from sensitivity ones, and 100% for identifying the NPC subjects from healthy ones. This work demonstrates the potential of molecular separation-assisted label-free SERS combined with machine learning for NPC screening and treatment strategy guidance in clinical scenario.

Long-stranded non-coding RNAs (lncRNA) have important roles in disease as transcriptional regulators, mRNA processing regulators and protein synthesis factors. However, traditional methods for detecting lncRNA are time-consuming and labor-intensive, and the functions of lncRNA are still being explored. Here, we present a surface enhanced Raman spectroscopy (SERS) based biosensor for the detection of lncRNA associated with liver cancer (LC) as well as in situ cellular imaging. Using the dual SERS probes, quantitative detection of lncRNA (DAPK1-215) can be achieved with an ultra-low detection limit of 952 aM by the target-triggered assembly of core-satellite nanostructures. And the reliability of this assay can be further improved with the R2 value of 0.9923 by an internal standard probe that enables the signal dynamic calibration. Meanwhile, the high expression of DAPK1-215 mainly distributed in the cytoplasm was observed in LC cells compared with the normal ones using the SERS imaging method. Moreover, results of cellular function assays showed that DAPK1-215 promoted the migration and invasion of LC by significantly reducing the expression of the structural domain of death associated protein kinase. The development of this biosensor based on SERS can provide a sensitive and specific method for exploring the expression of lncRNA that would be a potential biomarker for the screening of LC.

Surface enhanced Raman spectroscopy (SERS) utilizes the fingerprint features of molecular vibrations to identify and detect substances. However, in traditional single focus excitation scenarios, its signal collection efficiency of the objective is restricted. Furthermore, the uneven distribution of samples on the SERS substrate would result in poor signal stability, while the excitation power is limited to avoid sample damage. SERS detection system always requires precise adjustment of focal length and spot size, making it difficult for point-of-care testing applications. Here, we proposed a SERS microfluidic chip with barium titanate microspheres array (BTMA) embedded using vacuum self-assembled hot-pressing method for SERS detection with simultaneous enhancement of sensitivity and stability. Due to photonic nano-jets and directional antenna effects, high index microspheres are perfect micro-lens for effective light focusing and signal collecting. The BTMA can not only disperse excitation beam into an array of focal points covering the target uniformly with very low signal fluctuation, but enlarge the power threshold for higher signal intensity. We conducted a proof-of-principle experiment on chip for the detection of bacteria with immuno-magnetic tags and immuno-SERS tags. Together with magnetic and ultrasonic operations, the target bacteria in the flow were evenly congregated on the focal plane of BTMA. It demonstrated a limit of detection of 5 cells/mL, excellent signal reproducibility (error∼4.84%), and excellent position tolerance of 500 μm in X-Y plane (error∼5.375%). It can be seen that BTMA-SERS microfluidic chip can effectively solve the contradiction between sensitivity and stability in SERS detection.

Although diffusion gradient in thin-film technique (DGT) has realized the in-situ sampling Sulfamethazine (SMT), the traditional DGT devices cannot be served as sensing devices but in-situ sampling devices. Here we report a recyclable surface enhanced Raman scattering (SERS) responsive DGT sensing device (recyclable SERS-DGT Sensing Device) capable of in-situ sensing of SMT in water. This is achieved by innovatively utilizing a recyclable SERS responsive liquid suspension of Au nanoparticles supported on g-C3N4 (Au@g-C3N4NS) as DGT binding phase. Au@g-C3N4NS is synthesized via in-situ growth method and embed in DGT binding phase, which exhibits good SERS activity, aqueous stability recyclable and adsorption performance. The SERS-DGT Sensing Device is valid for measuring SMT under a wide range of conditions (i.e., deployment time 24∼180 h, concentrations range of 1.031∼761.9 ng mL-1, pH 5∼9, ionic strength 0.0001∼0.05 mol L-1 NaCl, DOM concentrations 0∼100 mg L-1, four recycles). Furthermore, substrate combined with DGT binding phase, can integrate the sampling, pretreatment and SERS detection of SMT, which can be recycled, improving the reliability and efficiency of environmental monitoring. In this article, recyclable SERS-DGT Sensing Device, a platform for recyclable in-situ sensing of antibiotics, holds great potential for environmental monitoring.

Noble metal has always been used as a preferred base for SERS substrate. However, the preparation cost of such materials is trully high. Therefore, many researchers have begun to search for succedanea which cost were lower. In this work, CsPbBr3@ZIF-8 was synthesized by in-situ reduction method and combined with graphene nanosheets to construct a SERS substrate. The SERS performance of this substrate could be further enhanced by the synergistic effect of perovskite quantum dots and graphene. Base on this material, a sensitive SERS strategy composed of CsPbBr3@ZIF-8@G, antibody, and Bradford method was developed for the quantitative determination of cardiac troponin I (cTnI) in human serum. It\'s worth noting that the sensitivity and accuracy of this method could approach the level of other SERS methods using noble metals. The \"reverse\"-SERS method could improve the uniformity and stability of detection platform obviously. The detection range of this method was 0.01-100 ng/mL, and the estimated detection of limit (LOD) was 4.7 pg/mL. The recovery rate of this method range was between 93.1 % and 104.8 %, and RSD range was between 4.47 % and 7.06 %.

Although diffusion gradient in the thin-film technique (DGT) is highly regarded in environmental analysis, the traditional DGT devices cannot serve as sensing devices but in situ sampling devices. Here we report a surface enhanced Raman scattering (SERS) responsive DGT sensing device (SERS-DGT Sensor) capable of on-site determination of organic contaminants underwater. This is achieved by innovatively utilizing a SERS responsive liquid suspension of Au nanoparticles supported on graphene oxide (AuNPs@GO) as the DGT binding phase. Liquid suspension is synthesized via a combined secondary growth and molecular welding approach and used as DGT binding phase AuNPs@GO exhibit good SERS activity, aqueous stability, and adsorption performance. Based on the development time range of 24-144 h, the measurement of sulfadiazine (SMT) by SERS-DGT Sensor is evaluated in the concentration range of 0.3289-2631 ng mL-1. The SERS-DGT sampler is valid for measuring SMT under a wide range of environmental conditions (i.e, pH 5-9, ionic strength 0.0001-0.05 mol L-1 NaCl, DOM concentrations 0-100 mg L-1, the values of TC: SMT ≤ 20 and MNZ: SMT ≤ 20). SERS-DGT Sensor is applied to the practical test of SMT content in pig breeding wastewater, and compared with the grab sampling method, the results confirm that this novel hyphenated technique exhibits good accuracy and precision. The platform proves to be versatile by extending the method to the monitoring of rhodamine 6G, metronidazole, fluoxetine, and enrofloxacin. In this article, SERS-DGT Sensor, a platform for directly on-site sensing of organic DGT, holds great potential for in situ sampling and on-site sensing for a wide range of organics and provides a new idea for environmental monitoring.

Rapid and accurate detection of rare circulating tumor cells (CTCs) in human blood still remains a challenge. We present a surface enhanced Raman spectroscopy (SERS) method based on aptamer-SERS bio-probe recognition coupled with micropore membrane filtration capture for the detection of CTCs at single cell level. The parylene micropore membrane with optimized micropore size installed on a filtration holder could capture bio-probe labeled CTCs by gravity in less than 10 s, and only with very less white blood cells (WBCs) residual. In order to facilitate the synthesis of the aptamer-SERS bio-probe, ethyl acetate dehydration method was established. The bio-probe can be rapidly synthesized within 2 h by binding SH-aptamer to 4- mercaptobenzoic acid (4-MBA) modified AuNPs with the help of ethyl acetate. The SERS bio-probe with selected specific aptamer could distinguish single human non-small cell lung cancer A549 cells from residual WBCs on membrane efficiently and reliably based on their Raman signal intensity difference at 1075 cm-1. Through the filter membrane coupled with aptamer-SERS bio-probe system, even 20 A549 cells in blood solution simulating CTCs sample can be detected, which the recovery rate and recognition rate are more than 90%. This method is rapid, reliable and cost-effective, which indicates a good prospect in clinical application for CTCs detection.

Microplastics (MPs) and Nanoplastics (NPs) accumulated in the environment have been identified as a major global issue due to their potential harm to wildlife. Current research in the detection of MPs is well established. However, the detection of NPs remains challenging. The aim of this paper is to investigate the detection of polystyrene (PS) NPs on a super-hydrophobic substrate using surface-enhanced Raman spectroscopy (SERS) technology after high-speed centrifugation of PS NPs and AgNPs. The hydrophobic substrate reduces the contact area of droplet, concentrating PS NPs and AgNPs on a small spot, which eliminates the random distribution of nano particles. The condensed PS NPs and AgNPs improve the SERS intensity, reproductivity and detection sensitivity. The results show that SERS measurement on a hydrophobic substrate could significantly improve the detection sensitivity of PS NPs, with the detection limits of PS NPs as low as 0.5 mg/L (500 nm PS NPs) and 1 mg/L (100 nm PS NPs). The study provides an effective and rapid method for the detection of NPs at trace concentration, demonstrating more possibility for the future detection of trace NPs in the aquatic environment.