In Situ Collection and SERS Detection of Nitrite in Exhalations on Facemasks Based on Wettability Differences.

As one of the common carriers of biological information, along with human urine specimens and blood, exhaled breath condensate (EBC) carries reliable and rich information about the body's metabolism to track human physiological normal/abnormal states and environmental exposures. What is more, EBC has gained extensive attention because of the convenient and nondestructive sampling. Facemasks, which act as a physical filter barrier between human exhaled breath and inhaled substances from the external environment, are safe, noninvasive, and economic devices for direct sampling of human exhaled breath and inhaled substances. Inspired by the ability of fog collection of Namib desert beetle, a strategy for in situ collecting and detecting EBC with surface-enhanced Raman scattering is illustrated. Based on the intrinsic and unique wettability differences between the squares and the surrounding area of the pattern on facemasks, the hydrophilic squares can capture exhaled droplets and spontaneously enrich the analytes and silver nanocubes (AgNCs), resulting in good repeatability in situ detection. Using R6G as the probe molecule, the minimal detectable concentration can reach as low as 10-16 M, and the relative standard deviation is less than 7%. This proves that this strategy can achieve high detection sensitivity and high detection repeatability. Meanwhile, this strategy is applicable for portable nitrite analysis in EBC and may provide an inspiration for monitoring other biomarkers in EBC.

Fear of childbirth among pregnant women: A concept analysis.

AIM: To clarify the concept of fear of childbirth among pregnant women and to examine its current measure tools. BACKGROUND: Fear of childbirth is a psychological symptom, prevalent among pregnant women, which negatively impacts women's health and well-being. It has become an increasingly concerning issue in perinatal mental health. However, due to its poor conceptualization, it presents difficulty in conducting reliable assessments and identifying risk factors. METHODS: The Walker and Avant approach to concept analysis guided this review. Six bibliographic databases were systematically searched for published research from their inception date to May 2023. Additional records were identified by manually searching the reference lists of relevant studies. Quantitative and qualitative studies investigating fear of childbirth in pregnant women were included. RESULTS: Three critical attributes have been identified: cognitive impairments, affective disorders and somatic symptoms. Antecedents include perceived a real or anticipated threat of pregnancy or its outcomes, low perceived self-coping ability and unmet social support needs. Consequences include processing and avoiding behaviours. This study also identified the dimensions of fear of childbirth, including 6 primary categories and 14 subcategories. The content of five scales was analysed and none covered all domains. CONCLUSIONS: The current analysis provides healthcare providers with a more comprehensive framework to assess and identify fear of childbirth. Further research is needed to develop a suitable instrument that covers all the attributes and dimensions of this concept and assesses its severity. IMPACT: This conceptual analysis provides a comprehensive insight into the phenomenon of fear of childbirth. This will help family members, healthcare providers and policymakers to identify the psychological needs of pregnant women and improve the quality of antenatal care. PATIENT OR PUBLIC CONTRIBUTION: Not applicable as no new data were generated.

Template-confined assembly of Ag nanocubes: An approach to fabricate SERS substrate with good performance.

Surface-enhanced Raman scattering (SERS) is an important analytical technique. Its detection sensitivity and reproducibility depend on the density and distribution of SERS hotspots. Self-assembly is an efficient method to produce of SERS substrates due to its easy accessibility. However, the assembled defects can hardly be avoided on large area, which could lower the density and uniformity of the hotspots, leading to poor SERS performance. Herein, we report a method to reduce the defects by taking a patterned substrate as template to confine the assembly of Ag nanocubes. The template was prepared based on the combination of photo lithography and self-assembly. Confined by the template, the Ag nanocubes were assembled closely in each dots of the pattern. The limit of detection (LOD) is down to 3.42 × 10-17 M and the enhanced factor (EF) is up to 3.44 × 1010 on the prepared substrate for detecting rhodamine 6G (R6G). In addition, the relative standard deviation (RSD) of the different substrates is 8.75 %. The assembled Ag nanocubes exhibits high sensitivity and reproducibility as SERS substrate, which are contributed by the formation of high-density and uniform hotspots. The prepared substrate can be used for detecting trace amounts of melamine in milk with LOD of 2.06 × 10-7 M and RSD of 6.91 %, so the substrate is applicable for analyzing various analytes.

Fabrication of Flexible Pyramid Array as SERS Substrate for Direct Sampling and Reproducible Detection.

Rapid extraction and analysis of target molecules from irregular surfaces are in high demand in the field of on-site analysis. Herein, a flexible platform used for surface-enhanced Raman scattering (SERS) based on an ordered polymer pyramid structure with half-imbedded silver nanoparticles (AgNPs) was prepared to address this issue. The fabrication includes the following steps: (1) creating inverted pyramid arrays in silicon substrate, (2) preparing a layer of AgNPs on the surface of the inverted pyramids, and (3) obtaining a substrate with an ordered polymer pyramids array with half-imbedded AgNPs by the molding method. This flexible substrate is capable of rapid extraction via a simple and convenient "paste and peel off" method. In addition, the substrate exhibits great repeatability and good sensitivity thanks to the uniformity and larger surface area of the ordered pyramids. The density of "hot spots" (local electromagnetic field with high intensity) is increased on the structured surface. Semi-imbedding silver particles in the polymer pyramids makes "hot spots" robust on the substrate. In addition, the preprepared silicon template with the inverted pyramids can be reused, which greatly reduces the production cost. With this substrate, we successfully analyzed thiram molecules on the epidermis of apples, cucumbers, and oranges, and the detection limits are 2.4, 3, and 3 ng/cm2, respectively. These results demonstrate the great potential of the substrate for in situ analysis, which can provide reference for the design of ideal SERS substrates.

Increasing hotspots density for high-sensitivity SERS detection by assembling array of Ag nanocubes.

Trace analysis has great promise in the fields of disease diagnosis and environment protection. Surface-enhanced Raman scattering (SERS) has wide range of utilization due to its reliable fingerprint detection. However, the sensitivity of SERS still needs to be enhanced. Raman scattering of target molecules around hotspots, the area with extremely strong electromagnetic field, can be highly amplified. Therefore, to increase the density of hotspots is one of the major approaches for enhancing the detection sensitivity of target molecules. In this paper, an ordered array of Ag nanocubes was assembled on a thiol modified silicon substrate as a SERS substrate, which provided high-density hotspots. The detection sensitivity is demonstrated by the limit of detection, which is down to 10-6 nM with Rhodamine 6G as probe molecule. The wide linear range (10-7-10-13 M) and low relative standard deviation (<6.48%) indicate the good reproducibility of the substrate. Furthermore, the substrate can be used for the detection of dye molecules in lake water. This method provides an approach for increasing hotspots of SERS substrate, which could be a promising method to achieve good reproducibility and high sensitivity.

Enhancing Detection Reproducibility of Surface-Enhanced Raman Scattering by Controlling Analytes under One Laser Spot.

Surface-enhanced Raman scattering (SERS), as a sensitive analytical technique, is expected to be used for quantification of trace analytes. At the current stage, high detection reproducibility should be guaranteed for realizing quantification analysis of trace analytes. The main obstacle to achieving high detection reproducibility is the nonuniform distribution of analyte molecules on substrates, particularly, the "coffee-ring" effect introduced by the flow of solute to the pinning of the contact line. Herein, we report a method to tackle this problem by controlling the location of analytes through tuning the wettability of the SERS substrate. With the combination of silver-assisted chemical etching and photolithography, the ordered Si patterns grafted silver nanoparticles with tunable wettability were integrated into a SERS substrate. With this substrate, high detection reproducibility was achieved by confining all the analyte molecules on the area of active plasmonic hot-spots within one laser, and the quantitative analysis was realized with ultrahigh sensitivity. Furthermore, the substrate is applicable for high-throughput detection.

Laser desorption/ionization on nanostructured silicon: morphology matters.

The surface morphology of the silicon nanostructure plays a crucial role in the laser desorption/ionization (LDI) process. Understanding the correlation between the surface morphology and LDI performance is the foundation for creating silicon substrates with high LDI efficiency. Most of the present studies focus only on the structural parameters (such as porosity, depth, total surface area, dimension, etc.) of a single structure, but their effects on LDI efficiency vary with the types of silicon structures. Herein, two representative types of silicon nanostructures, porous silicon (PSi) and thorny silicon (TSi), were created to address this issue. The results indicate that the PSi substrate can generate a stronger heat effect and is beneficial to desorption; the TSi substrate can facilitate electron transfer and is favorable to ionization. Subsequently, the assertion was further confirmed by simultaneously detecting a dozen of standard samples and a real sample on both the TSi and PSi substrates, in which PSi can significantly enhance the detection signals of organic salts, whereas the TSi substrate can greatly increase the LDI efficiencies of neutral analytes. This finding provides a foundation for improving the LDI performance by tailoring silicon nanostructures, which is helpful for designing and creating substrates with high LDI performance.

[Effects of anti-survivin oligonucleotides on growth of peritoneally implanted ovarian cancer xenografts in nude mice].

OBJECTIVE: To observe the effect of anti-survivin oligonucleotides (ASODN) on the invasion and growth of peritoneally implanted ovarian cancer cell xenografts in nude mice. METHODS: Nude mouse models bearing peritoneally implanted ovarian cancer cell (SKOV3) xenografts were established and subjected to intraperitoneal injection of survivin ASODN or saline (control). The number and weight of the intraperitoneal xenografts were compared between the two groups.The expressions of interleukin (IL-6), signal transducer and activator of transcription3 (STAT3), phosphorylated STAT3 (p-STAT3), and survivin protein in the tumor tissues were detected with Western blotting in both groups. RESULTS: Compared with those in the control group, the number and weight of the intraperitoneal xenografts were significantly reduced in ASODN group (P<0.05). ASODN treatment also resulted in significantly lowered protein levels of IL-6, STAT3, p-STAT3, and survivin in the tumor tissues (P<0.05). CONCLUSION: Survivin ASODN can suppress the invasion and migration capacity of ovarian cancer cells and inhibit peritoneal metastasis of the tumor in nude mice possibly though down-regulation of IL-6/STAT3 signaling pathway.