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Au@Pt core-satellite nanoparticles (CSNPs) with dual-functionality as both catalyst and surface-enhanced Raman scattering (SERS) substrate are successfully synthesized by decorating Pt nanocrystals on plasmonic Au colloids. The coupling "hotspot" structures at the Au-Pt interface significantly promotes the catalytic decarboxylation reaction, and provides spectroscopic insights into the molecule-plasmon interface in universal plasmon-promoted catalytic reactions. [Display omitted] Plasmon-induced hot carriers are a promising "active" energy source, attracting increasing attention for their potential applications in photocatalysis and photodetection. Here, we hybridize plasmonic Au spherical nanoparticles (SNPs) with catalytically active Pt nanocrystals to form Au@Pt core-satellite nanoparticles (CSNPs), which act as both an efficient catalyst for plasmon-promoted decarboxylation reaction and a robust surface-enhanced Raman scattering (SERS) substrate for plasmon-enhanced molecular spectroscopic detection. By regulating the coverage of Pt nanocrystals on the Au SNPs, we modulated the "hotspot" structures of the Au@Pt CSNPs to optimize the SERS detecting capability and catalytic decarboxylation performance. The coupling functionalities enable us with unique opportunities to in-situ SERS monitor universal reactions catalyzed by active catalysts (e.g. Pt, Pd) in the chemical industry in real-time. The decarboxylation rate of 4-mercaptophenylacetic acid was dynamically controlled by the surface catalytic decarboxylation step, following first-order overall reaction kinetics. Moreover, the reaction rate exhibited a strong correlation with the local field enhancement |E/E 0 |4 of the hotspot structure. This work provides spectroscopic insights into the molecule-plasmon interface under the plasmon-promoted catalytic reactions, guiding the rational design of the plasmonic interface of nanocatalysts to achieve desired functionalities. [ABSTRACT FROM AUTHOR]

When decorated with plasmonic nanoparticles, pulled optical nanofibers are compatible with plasmonic techniques enabling the ability to probe microenvironments with high spatial and temporal resolution. Although the nanofibers exhibit excellent compatibility for biological samples including cells and tissues, the underlying interactions between the dielectric fiber, plasmonic nanoparticles, and the incident light have been minimally explored. It is shown that the complex coupling of optical and plasmonic properties within the nanofiber strongly influences both the surface‐enhanced Raman scattering (SERS) and photothermal capabilities. Through a combination of experimental results and simulated electric field distributions and spectra it is demonstrated that, although the nanofibers may be homogeneously decorated with gold nanoparticles, the optical effects spatially differ. Specifically, the SERS performance varies periodically based on the diameter of the nanofiber, which is associated with ring resonator modes, while the photothermal effects are more homogeneous over the same diameters, highlighting differences in optoplasmonic properties at this length scale. Through understanding these effects, it may become possible to control temperatures and SERS properties to evaluate processes with micrometric spatial resolution, such as the analytes secreted during temperature‐induced death of single cells. [ABSTRACT FROM AUTHOR]

Surface‐enhanced Raman scattering (SERS) sensors typically employ nanophotonic structures that support high‐field confinement and enhancement in hotspots to increase the Raman scattering from target molecules by orders of magnitude. In general, high field and SERS enhancement can be achieved by reducing the critical dimensions and mode volumes of the hotspots to nanoscale. To this end, a multitude of SERS sensors employing photonic structures with nanometric hotspots have been demonstrated. However, delivering analyte molecules into nanometric hotspots is challenging, and the trade‐off between field confinement/enhancement and analyte delivery efficiency is a critical limiting factor for the performance of many nanophotonic SERS sensors. Here, a new type of SERS sensor employing solid‐metal nanoparticles and bulk liquid metal is demonstrated to form nanophotonic resonators with a nanoparticle‐on‐liquid‐mirror (NPoLM) architecture, which effectively resolves this trade‐off. In particular, this unconventional sensor architecture allows for the convenient formation of nanometric hotspots by introducing liquid metal after analyte molecules are efficiently delivered to the surface of gold nanoparticles. In addition, a cost‐effective and reliable process is developed to produce gold nanoparticles on a substrate suitable for forming NPoLM structures. These NPoLM structures achieve two orders of magnitude higher SERS signals than the gold nanoparticles alone. [ABSTRACT FROM AUTHOR]

Currently, empirical therapy regimens are often used in the treatment of infectious diseases that are not based on data on pathogen resistance. One of the main reasons for the unjustified prescription of antibacterial drugs is the lack of rapid and at the same time universal methods of determining the antibiotic resistance of the pathogen. The most widely used culture techniques, such as the microdilution method, require a long time to generate the necessary number of bacterial cells. Less time-consuming methods of resistance assessment (genomic or proteomic) are based on the determination of specific markers (resistance genes, overexpression of certain proteins, etc.); in this case, the specific protocol is most often applicable to a narrow number of both microorganism strains and antibiotics. Previously, we demonstrated the possibility of using Raman spectroscopy (RS) technology for quantitative determination of the product of bacterial cell activity in the MTT assay, formazan, directly in the cell suspension. The absence of the formazan isolation step simplifies the assay and increases its accuracy. The analysis time did not exceed 2 h while maintaining the versatility of the MTT assay itself. Limitations of the developed protocol for RS detection of the MTT assay results include a high sensitivity threshold of 107 CFU/mL for the bacterial cell concentration, so a preliminary stage of cultivation is necessary for samples with a low bacterial content. Here, we propose a method to increase the sensitivity of formazan determination by utilizing the effect of surface-enhanced Raman scattering (SERS) on gold nanoparticles. As a result of this study, the optimal conditions for SERS analysis of formazan in both solution and suspension of Escherichia coli cells are selected. Formazan signal amplification due to the use of SERS on gold nanoparticles instead of RS allowed us to reduce the sensitivity threshold for the number of bacterial cells in the sample by at least 30 times, up to 3 × 105 CFU/mL. This sensitivity is not the limit of the SERS technology capabilities because the introduction of other types of nanoparticles (more optimal in shape, size, concentration, etc.) into the experiment will allow one to achieve even higher signal amplification. [ABSTRACT FROM AUTHOR]

Surface-enhanced Raman scattering (SERS) holds significant potential across environmental monitoring, materials science, and biomedical applications. However, challenges regarding ultra-sensitive detection and repeatability are bottlenecks for practical applications, especially in terms of detection uniformity. In this study, we utilized surface acoustic waves (SAW) in conjunction with Raman spectroscopy to actively enrich 5 μL of 50 nm gold nanoparticles (AuNPs), thereby achieving innovative SERS-active sensing. This dynamic enrichment process enables the dense and uniform aggregation of AuNPs in droplets, thereby facilitating reliable ultrasensitive detection. The SAW system was further optimized through hydrophobic surface treatment. Using 4-mercaptobenzoic acid as a probe analyte, our SAW-SERS method successfully detected concentrations as low as 10−8 mol/L. The surface acoustic waves had the capability to significantly amplify Raman signal intensity up to 100 compared to conventional drying methodologies. This SAW-induced AuNP clustering technology offers a rapid, label-free SERS sensing method characterized by exceptional sensitivity and uniformity. [ABSTRACT FROM AUTHOR]

Macrophages are among the most important components of the innate immune system where the interaction of pathogens and their phagocytosis occur as the first barrier of immunity. When nanomaterials interact with the human body, they have to face macrophages as well. Thus, understanding of nanomaterials-macrophage interactions and underlying mechanisms is crucial. For this purpose, various methods are used. In this study, surface-enhanced Raman scattering (SERS) is proposed by studying lipopolysaccharide (LPS) induced macrophage polarization using gold nanoparticles (AuNPs) as an alternative to the current approaches. For this purpose, the murine macrophage cell line, RAW 264.7 cells, was polarized by LPS, and polarization mechanisms were characterized by nitrite release and reactive oxygen species (ROS) formation and monitored using SERS. The spectral changes were interpreted based on the molecular pathways induced by LPS. Furthermore, polarized macrophages by LPS were exposed to the toxic AuNPs doses to monitor the enhanced phagocytosis and related spectral changes. It was observed that LPS induced macrophage polarization and enhanced AuNP phagocytosis by activated macrophages elucidated clearly from SERS spectra in a label-free non-destructive manner. [ABSTRACT FROM AUTHOR]

The development of an innovative approach is explored to amplify the signal of a surface-enhanced Raman scattering (SERS)-based detection system using a novel nanotag: Au@Ag NPs covered by satellite AuNPs and conjugated by 4-mercaptbenzoic acid (4-MBA) as a Raman tag (Au@Ag-MBA-AuNPs). The Au@Ag-MBA-AuNPs nanotags showed strong SERS activities with an enhancement factor in the 108 order of magnitude. This indicates the formation of many hot spots due to the combination of core–shell nanoparticles and satellite AuNPs on the surface of Au@Ag-MBA NPs. The newly fabricated nanotags were employed in a small-sized Palmtop Raman spectrometer. A concentration-dependent increase in SERS intensity was observed in the norovirus-like particle (NoV-LP) concentration range 10 fg/mL to 100 pg/mL with a detection limit of 0.76 fg/mL. Even in the severe interfering matrices, this detection method's coefficient of variation was less than 10%. This detection system was approximately 107 times more sensitive than commercially available ELISA kits. Norovirus in clinical samples was detected over a wide concentration range of 1.0 × 101 – 1.0 × 106 RNA copy number/mL with a detection limit of 7.8 RNA copy number/mL, indicating sensitivity comparable to real-time PCR. These results suggest that this detection system is stable in a complex matrix and has the potential for detecting norovirus in clinical samples with a small Palmtop Raman spectrometer. [ABSTRACT FROM AUTHOR]

A versatile method is invented to self‐assemble gold nanoparticles (GNPs) into nanoclusters (NCs) of various morphologies. By storing the particles in toluene, a highly non‐polar solvent, under conditions that ensure particle stability, the success rate of subsequent assembly can be enhanced. Additionally, conducting particle self‐assembly at a stirring speed of 200 rpm allows the NCs to maintain a spherical shape. The relative standard deviation (RSD) of Raman spectral peaks of multiple NCs used as surface‐enhanced Raman spectroscopy (SERS) substrates is calculated to be less than 10%, effectively addressing the issue of low repeatability when using NCs as SERS substrates. Furthermore, even at an analyte concentration reduced to 10−9 m, a SERS characteristic peak intensity of approximately 2 × 103 is measurable, demonstrating the high sensitivity of the assembled structures. Finally, by detecting SERS signals from NCs of varying sizes, the intensities of characteristic peaks tend to converge, eliminating the influence of morphology and size on SERS detection. [ABSTRACT FROM AUTHOR]

A ratiometric SERS aptasensor based on catalytic hairpin self-assembly (CHA) mediated cyclic signal amplification strategy was developed for the rapid and reliable determination of Escherichia coli O157:H7. The recognition probe was synthesized by modifying magnetic beads with blocked aptamers, and the SERS probe was constructed by functionalizing gold nanoparticles (Au NPs) with hairpin structured DNA and 4-mercaptobenzonitrile (4-MBN). The recognition probe captured E. coli O157:H7 specifically and released the blocker DNA, which activated the CHA reaction on the SERS probe and turned on the SERS signal of 6-carboxyl-x-rhodamine (ROX). Meanwhile, 4-MBN was used as an internal reference to calibrate the matrix interference. Thus, sensitive and reliable determination and quantification of E. coli O157:H7 was established using the ratio of the SERS signal intensities of ROX to 4-MBN. This aptasensor enabled detection of 2.44 × 102 CFU/mL of E. coli O157:H7 in approximately 3 h without pre-culture and DNA extraction. In addition, good reliability and excellent reproducibility were observed for the determination of E. coli O157:H7 in spiked water and milk samples. This study offered a new solution for the design of rapid, sensitive, and reliable SERS aptasensors. [ABSTRACT FROM AUTHOR]

Practical application of surface-enhanced Raman spectroscopy (SERS) has suffered from several limitations by heterogeneous distribution of hot-spots, such as high signal fluctuation and the resulting low reliability in detection. Herein, we develop a strategy of more sensitive and reliable SERS platform through designing spatially homogeneous gold nanoparticles (GNPs) on a uniform gold nanoisland (GNI) pattern. The proposed SERS substrate is successfully fabricated by combining two non-lithographic techniques of electron beam evaporation and convective self-assembly. These bottom-up methods allow a simple, cost-effective, and large-area fabrication. Compared to the SERS substrates obtained from two separate nanofabrication methods, Raman spectra measured by the samples with both GNPs and GNIs present a significant increase in the signal intensity as well as a notable improvement in signal fluctuation. The simulated near-field analyses demonstrate the formation of highly amplified plasmon modes within and at the gaps of the GNP-GNI interfaces. Moreover, the suggested SERS sensor is evaluated to detect the glucose concentration, exhibiting that the detection sensitivity is improved by more than 10 times compared to the sample with only GNI patterns and a fairly good spatial reproducibility of 7% is accomplished. It is believed that our suggestion could provide a potential for highly sensitive, low-cost, and reliable SERS biosensing platforms that include many advantages for healthcare devices. [ABSTRACT FROM AUTHOR]

A convenient self-assembly method is proposed for synthesis of 3D Au/MOF-808 (Zr) composite nanostructures with a cerium metal-organic framework loaded with gold nanoparticles. We combine adsorption properties of MOF materials with surface plasmon resonance of noble metals to construct hotspot-dense 3D Au/MOF-808 (Zr) SERS substrates, by using a two-step method of solvothermal and reduction reactions. The results show that optimal SERS substrates are obtained from a volume ratio of gold nanoparticles to MOF-808 (Zr) solution of 4:1 and a self-assembly time of 2 h. Rhodamine 6G (R6G) is used as a molecular probe to characterize and analyze SERS properties of substrates of 3D Au/MOF-808 (Zr) prepared under the optimal process conditions, where the substrates are capable to detect R6G concentrations down to 10–10 M with a relative standard deviation of 8.81%. Finally, we applied the SERS substrates of 3D Au/MOF-808 (Zr) to the detection of pesticide thiram, and establish a quantitative determination method. 3D Au/MOF-808 (Zr) provides a sensitive detection of thiram in lake water by SERS with a detection limit of 1.49 × 10−9 M. Application tests show that a SERS enhancement factor of the MOF-based SERS substrates for the detection of thiram can be significantly increased to 5.91 × 105. Thus, the above results indicate that such substrate has high sensitivity, good adsorption, homogeneity, and reproducibility, which can be extended for sensitive detection of pesticide residues in food and environment. [ABSTRACT FROM AUTHOR]

[Display omitted] Developing innovative surface-enhanced Raman scattering (SERS) nanotags continues to attract significant attention due to their unparalleled sensitivity and specificity for in vitro diagnostic and in vivo tumor imaging applications. Here, we report a new class of bright and stable SERS nanotags using alkylmercaptan-PEG (AMP) polymers. Due to its amphiphilic structure and a thiol anchoring group, these polymers strongly absorb onto gold nanoparticles, leading to an inner hydrophobic layer and an outer hydrophilic PEG layer. The inner hydrophobic layer serves to "lock in" the Raman reporter molecules adsorbed on the particle surface via favorable hydrophobic interactions that also allow denser PEG coatings, which "lock out" other molecules from competitive binding or adsorbing to the gold surface, thereby providing superior colloidal and signal stability. The higher grafting densities of AMP polymers compared to conventional thiolated PEG also led to dramatic increases in cellular target selectivity, with specific-to-nonspecific binding ratios reaching beyond an order of magnitude difference. Experimental evaluations and theoretical considerations of dielectric polarization and light scattering indicate that the hydrophobic layer provides a more favorable dielectric environment with less plasmon dampening, greater particle scattering efficiency, and increased Raman reporter polarizability. Accordingly, SERS nanotags with AMP polymer coatings are observed to be considerably brighter (∼10-fold). Furthermore, the AMP-coated SERS nanotag's increased intensity and avidity can boost cellular detection sensitivity by nearly two orders of magnitude. [ABSTRACT FROM AUTHOR]

Surface-enhanced Raman scattering (SERS), as one of the most powerful analytical methods, undertakes important inspection tasks in various fields. Generally, the performance of an SERS-active substrate relies heavily on its structure, which makes it difficult to integrate multiple-functional detectability on the same substrate. To address this problem, here we designed and constructed a film of graphene/Au nanoparticles (G/Au film) through a simple method, which can be conveniently transferred to different substrates to form various composite SERS substrates subsequently. By means of the combination of the electromagnetic enhancement mechanism (EM) and the chemical enhancement mechanism (CM) of this structure, the film realized good SERS performance experimentally, with the enhancement factor (EF) approaching ca. 1.40 × 105. In addition, the G/Au film had high mechanical strength and had large specific surface area and good biocompatibility that is beneficial for Raman detection. By further transferring the film to an Ag/Si composite substrate and PDMS flexible film, it showed enhanced sensitivity and in situ detectability, respectively, indicating high compatibility and promising prospect in Raman detection. [ABSTRACT FROM AUTHOR]

Gold nanoshells have been actively applied in industries beyond the research stage because of their unique optical properties. Although numerous methods have been reported for gold nanoshell synthesis, the labor-intensive and time-consuming production process is an issue that must be overcome to meet industrial demands. To resolve this, we report a high-throughput synthesis method for nanogap-rich gold nanoshells based on a core silica support (denoted as SiO2@Au NS), affording a 50-fold increase in scale by combining it with a dual-channel infusion pump system. By continuously dropping the reactant solution through the pump, nanoshells with closely packed Au nanoparticles were prepared without interparticle aggregation. The thickness of the gold nanoshells was precisely controlled at 2.3–17.2 nm by regulating the volume of the reactant solution added dropwise. Depending on the shell thickness, the plasmonic characteristics of SiO2@Au NS prepared by the proposed method could be tuned. Moreover, SiO2@Au NS exhibited surface-enhanced Raman scattering activity comparable to that of gold nanoshells prepared by a previously reported low-throughput method at the same reactant ratio. The results indicate that the proposed high-throughput synthesis method involving the use of a dual-channel infusion system will contribute to improving the productivity of SiO2@Au NS with tunable plasmonic characteristics. [ABSTRACT FROM AUTHOR]

The surface-enhanced Raman scattering (SERS) method is a widely used technique for molecular structure analysis. This method relies on the enhancement of the Raman signal through the use of plasmonic nanostructures, such as gold and silver, which serve as substrate sensors. The use of pre-made sensors can effectively enhance the efficiency and cost-effectiveness of SERS. In this study, we used a fast, simple, and cost-effective method to create a suitable substrate for SERS analysis. Initially, gold colloidal nanoparticles with dimensions ranging from 50 to 80 nm were synthesized and deposited onto glass slides to create a uniform and rough substrate. To stabilize the gold nanoparticles, a sulfur compound called "1-dodecanethiol" was selected, increasing the contact angle of the sample to 45° on the glass slide. Florfenicol, one of the most common antibiotic residues in muscle foods, was selected as an analyte. Spectrum acquisitions at various points on a single slide demonstrated acceptable substrate uniformity (RSD = 8.44%). Further experiments conducted on different slides confirmed the consistency of the results (RSD = 7.90%). Finally, the reliability of the results was confirmed through spectrum acquisitions over various time intervals (RSD = 1.26%).

Cyanine dyes are widely used in various techniques of bioimaging. The development of new types of optical tags with cyanine dyes combined with plasmonic nanoparticles is of great interest. In this work, surface-enhanced Raman scattering (SERS) study of optical behavior of cyanines adsorbed on gold nanoparticles in suspensions is presented to predict the optical response of corresponding tags. Two dyes, sulfo-cyanine 5.5 NHS ester and sulfo-cyanine 7.5 NHS ester were considered as they are suitable for the first transparency window of biological tissues. Gold nanoparticles of anisotropic shape were used as a plasmonic substrate. The assignment of bands in SERS spectra of both dyes was performed based on DFT calculations of vibrational frequencies of the molecules. The adsorption of dyes on the nanoparticles with different surface charges was studied. Spectral changes showed that a reorientation of the molecules occurs and reactive NHS ester tail is more accessible sterically in the case of a positive surface charge. The effect of aggregation-induced agent on the SERS response of sulfo-cyanines was also studied. Addition of chloride anions led to about five-fold increase of SERS intensity for sulfo-cyanine 5.5 NHS ester. [ABSTRACT FROM AUTHOR]

Uric acid (UA), the final metabolite of purine, is primarily excreted through urine to maintain an appropriate concentration in the bloodstream. However, any malfunction in this process can lead to complications due to either deficiency or excess amount of UA. Hence, the development of a sensor platform with a wide-range detection is crucial. To realize this, we fabricated a surface-enhanced Raman spectroscopy (SERS) substrate inspired by a type of starfish with numerous protrusions, Asterias forbesi. The Asterias forbesi-inspired SERS (AF-SERS) substrate utilized an Au@Ag nanostructure and gold nanoparticles to mimic the leg and protrusion morphology of the starfish. This substrate exhibited excellent Raman performance due to numerous hotspots, demonstrating outstanding stability, reproducibility, and repeatability. In laboratory settings, we successfully detected UA down to a concentration of 1.16 nM (limit of detection) and demonstrated selectivity against various metabolites. In the experiments designed for real-world application, the AF-SERS substrate detected a broad range of UA concentrations, covering deficiencies and excesses, in both serum and urine samples. These results underscore the potential of the developed AF-SERS substrate as a practical detection platform for UA in real-world applications. [ABSTRACT FROM AUTHOR]

The World Health Organization (WHO) declared in a May 2023 announcement that the COVID-19 illness is no longer categorized as a Public Health Emergency of International Concern (PHEIC); nevertheless, it is still considered an actual threat to world health, social welfare and economic stability. Consequently, the development of a convenient, reliable and affordable approach for detecting and identifying SARS-CoV-2 and its emerging new variants is crucial. The fingerprint and signal amplification characteristics of surface-enhanced Raman spectroscopy (SERS) could serve as an assay scheme for SARS-CoV-2. Here, we report a machine learning-based label-free SERS technique for the rapid and accurate detection and identification of SARS-CoV-2. The SERS spectra collected from samples of four types of coronaviruses on gold nanoparticles film, fabricated using a Langmuir–Blodgett self-assembly, can provide more spectroscopic signatures of the viruses and exhibit low limits of detection (<100 TCID50/mL or even <10 TCID50/mL). Furthermore, the key Raman bands of the SERS spectra were systematically captured by principal component analysis (PCA), which effectively distinguished SARS-CoV-2 and its variant from other coronaviruses. These results demonstrate that the combined use of SERS technology and PCA analysis has great potential for the rapid analysis and discrimination of multiple viruses and even newly emerging viruses without the need for a virus-specific probe. [ABSTRACT FROM AUTHOR]

Surface‐enhanced Raman scattering (SERS) is a sensitive and fast technique for sensing applications such as chemical trace analysis. However, a successful, high‐throughput practical implementation necessitates the availability of simple‐to‐use and economical SERS substrates. In this work, we present a robust, reproducible, flexible and yet cost‐effective SERS substrate suited for the sensitive detection of analytes at near‐infrared (NIR) excitation wavelengths. The fabrication is based on a simple dropcast deposition of silver or gold nanomaterials on an aluminium foil support, making the design suitable for mass production. The fabricated SERS substrates can withstand very high average Raman laser power of up to 400 mW in the NIR wavelength range while maintaining a linear signal response of the analyte. This enables a combined high signal enhancement potential provided by (i) the field enhancement via the localized surface plasmon resonance introduced by the noble metal nanomaterials and (ii) additional enhancement proportional to an increase of the applicable Raman laser power without causing the thermal decomposition of the analyte. The application of the SERS substrates for the trace detection of melamine and rhodamine 6G is demonstrated, which shows limits of detection smaller than 0.1 ppm and analytical enhancement factors on the order of 104 as compared to bare aluminium foil. [ABSTRACT FROM AUTHOR]

This paper reports a two-step method for preparing a metal-organic framework (MOF) MIL-101 (Fe) based substrate with high sensitivity and stability for surface-enhanced Raman scattering (SERS) analysis. Firstly, MIL-101 (Fe) nanoparticles were synthesized using a traditional solvothermal method. Next, gold nanoparticles (AuNPs) were produced through a reduction method, and the AuNPs/MIL-101 (Fe) composite substrate was created by combining MIL-101 (Fe) with AuNPs. The adsorption capacity of the substrate and its SERS activity after multiple cleaning were tested. Using Rhodamine 6 G (R6G) as the probe molecule, the substrate's detection capability reached 10-8 M, with a relative standard deviation (RSD) of approximately 13.15%, indicating excellent SERS performance and uniformity. The ideal detection capability for sulfapyridine using the composite matrix can be as low as 10-6 M. This proposed substrate is convenient and efficient, holding great potential for the rapid and sensitive detection of antibiotic residues and other environmental pollutants.

Ferroptosis is a non-apoptotic cell death regulated by iron-dependent lipid peroxidation. Glutathione (GSH), a key antioxidant against oxidative damage, is involved in one of the most important metabolic pathways of ferroptosis. Herein, an excellent plasmonic nanoprobe was developed for highly sensitive, in situ, dynamic real-time monitoring of intracellular GSH levels during ferroptosis. A nanoprobe was prepared by functionalizing gold nanoparticles (AuNPs) with the probe molecule crystal violet (CV). The fluctuation in the SERS signal intensity of CV via the competitive displacement reaction can be used to detect GSH. The advantages of the plasmonic nanoprobe including low-cost production techniques, outstanding stability and biocompatibility, high specificity and sensitivity towards GSH with a detection limit of 0.05 μM. It enables real-time dynamic monitoring of GSH levels in living cells during erastin-induced ferroptosis. This approach is expected to provide important theoretical support for elucidating the GSH-related ferroptosis metabolic mechanism and advancing our understanding of ferroptosis-based cancer therapy. [ABSTRACT FROM AUTHOR]

Raman spectroscopy exhibits potential as a tool for identifying the chemical composition of substances and has witnessed a growing application in urological oncology. This study undertook a bibliometric analysis to chart the present state and future prospects of Raman spectroscopy applications in urological tumors. The present study retrieved literature on the utilization of Raman spectroscopy in urological oncology from the Science Citation Index Expanded of Web of Science Core Collection, spanning from its inception to June 2023. Data from included studies were analyzed using CiteSpace, Python, and Excel. Our study examined 897 articles from 65 countries and identified a significant exponential growth in annual publications. The USA and China were prominent contributors to this field, with high publication rates and funding agencies. Shanghai Jiao Tong University emerged as the most influential institution. The journals Analytical Chemistry and Analyst were found to be the most productive. Our keyword analysis revealed an intense interest for "gold nanoparticle" and "pathology," with the most recent bursts occurring for "surface-enhanced Raman scattering (SERS)," "biomarkers," and "prostate specific antigen." As a detection tool, Raman spectroscopy holds the potential to assist in the identification, management, and prognostication of urological tumors. Notably, adjuvant diagnosis and prognosis evaluation based on SERS of tumor markers is a hot research topic. These findings offer valuable insights into the current state of Raman spectroscopy research in urological oncology, which could inform future studies and clinical practice. [ABSTRACT FROM AUTHOR]

A novel stimulus-responsive surface-enhanced Raman scattering (SERS) nanoprobe has been developed for sensitive glutathione (GSH) detection based on manganese dioxide (MnO2) core and silver/gold nanoparticles (Ag/Au NPs). The MnO2 core is not only capable to act as a scaffold to amplify the SERS signal via producing "hot spots", but also can be degraded in the presence of the target and thus greatly enhance the nanoprobe sensitivity for sensing of GSH. This approach enables a wide linear range from 1 to 100 µM with a 2.95 µM (3σ/m) detection limit. Moreover, the developed SERS nanoprobe represents great possibility in both sensitive detection of intracellular GSH and even can monitor the change of intracellular GSH level when the stimulant occurs. This sensing system not merely offers a novel strategy for sensitive sensing of GSH, but also provides a new avenue for other biomolecules detection. [ABSTRACT FROM AUTHOR]

We developed a reliable simple analysis of adenosine, creatinine and other nucleosides (cytidine and guanosine) with single measurement based on surface-enhanced Raman spectroscopy (SERS) using DSP-AuNPs with Cu2+ ions probe and applied it to achieve noninvasive screening of lung cancer. The gold nanoparticles (AuNPs) were modified with 3,3′-dithiodipropionic acid di (N-hydroxysuccinimide ester) (DSP), which could react with above mentioned molecules followed with the aggregation of AuNPs at the presence of Cu2+, thus form the plasmonic hot spots to dramatically increase their fingerprint Raman signal. The probe of DSP-AuNPs was applied for the detail analysis of urinary adenosine of healthy people and lung cancer patients. The SERS measurement indicated a higher concentration of urinary adenosine for lung cancer patients than that of healthy people, which was consistent with the results measured by high-performance liquid chromatography (HPLC). In combination of Raman spectroscopy with the orthogonal partial least squares discriminant analysis (OPLS-DA) model, we are able to discriminate the lung cancer patients from healthy people with the urinary test. The results indicated that besides of adenosine, other metabolites including uric acid, guanine and creatinine may also be the potential tumor markers in urine for the noninvasive lung cancer diagnosis. Such a method paves a way for the noninvasive cancer screening and it can be further modified for the detection of other molecules on medical diagnosis.

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The purpose of this paper is to provide an in-depth review of plasmonic metal nanoparticles made from rhodium, platinum, gold, or silver. We describe fundamental concepts, synthesis methods, and optical sensing applications of these nanoparticles. Plasmonic metal nanoparticles have received a lot of interest due to various applications, such as optical sensors, single-molecule detection, single-cell detection, pathogen detection, environmental contaminant monitoring, cancer diagnostics, biomedicine, and food and health safety monitoring. They provide a promising platform for highly sensitive detection of various analytes. Due to strongly localized optical fields in the hot-spot region near metal nanoparticles, they have the potential for plasmon-enhanced optical sensing applications, including metal-enhanced fluorescence (MEF), surface-enhanced Raman scattering (SERS), and biomedical imaging. We explain the plasmonic enhancement through electromagnetic theory and confirm it with finite-difference time-domain numerical simulations. Moreover, we examine how the localized surface plasmon resonance effects of gold and silver nanoparticles have been utilized for the detection and biosensing of various analytes. Specifically, we discuss the syntheses and applications of rhodium and platinum nanoparticles for the UV plasmonics such as UV-MEF and UV-SERS. Finally, we provide an overview of chemical, physical, and green methods for synthesizing these nanoparticles. We hope that this paper will promote further interest in the optical sensing applications of plasmonic metal nanoparticles in the UV and visible ranges. [ABSTRACT FROM AUTHOR]

Purpose: Current skin imaging modalities, including optical, electron, and confocal microscopy, mostly require tissue fixations that could damage proteins and biological molecules. Live tissue or cell imaging such as ultrasonography and optical coherent microscope may not adequately measure the dynamic spectroscopical changes. Raman spectroscopy has been adopted for skin imaging in vivo, mostly for skin cancer imaging. However, whether the epidermal and dermal thickening in skin could be measured and distinguished by conventional Ramen spectroscopy or the surface‐enhanced Raman scattering (SERS), a rapid and label‐free method for noninvasive measurement remains unknown. Methods: Human skin sections from patients of atopic dermatitis and keloid, which represent epidermal and dermal thickening, respectively, were measured by conventional Ramen spectroscopy. In mice, skin sections from imiquimod (IMQ)‐ and bleomycin (BLE)‐treated mice, which reflect the epidermal and dermal thickening, respectively, were measured by SERS, that incorporates gold nanoparticles to generate surface plasma and enhance Raman signals. Results: Conventional Ramen spectroscopy failed to consistently show the Raman shift in human samples among the different groups. SERS successfully revealed a prominent peak around 1300 cm−1 in the IMQ‐treated skin; and two significant peaks around 1100 and 1300 cm−1 in BLE‐treated group. Further quantitative analysis showed 1100 cm−1 peak was significantly accentuated in the BLE‐treated skin than that in control skin. SERS identified in vitro a similar 1100 cm−1 peak in solutions of collagen, the major dermal biological molecules. Conclusion: SERS distinguishes the epidermal or dermal thickening in mouse skin with rapid and label‐free measures. A prominent 1100 cm−1 SERS peak in the BLE‐treated skin may result from collagen. SERS might help precision diagnosis in the future. [ABSTRACT FROM AUTHOR]

With the recent developments in high‐sensitivity optical detection technologies, many studies have been conducted to accurately detect biomarkers with low concentrations of 1.0 pM or less as well as apply them to in vitro diagnostics. The tubulin‐associated unit (tau‐381) protein, a biomarker of Alzheimer's disease, is one such representative example, and its cut‐off value reported in clinical practice is 5.5 fM. Therefore, a robust sensing technology that can stably detect such low concentrations of biomarkers is needed. In this study, tau‐381 was detected with high sensitivity and reproducibility by a plasmonic Au nanopopcorn substrate fabricated via thermal evaporation. Here, aptamer DNAs labeled with Raman reporters on the terminal were used as the receptors. The plasmonic nanopopcorn substrate used in this study is composed of uniform gold nanoparticles (AuNPs) of average size 64 nm. The reproducibility was significantly improved through more uniform nanogaps than those formed by aggregation of AuNPs in solution. An assay was conducted by first reacting tau‐381 with the corresponding aptamers, and the remaining aptamer DNAs were then reacted with capture DNAs immobilized on the surface of the Au substrate. The assay results for tau‐381 showed a limit of detection value of 2.2 fM, which is below the cut‐off value (5.5 fM). [ABSTRACT FROM AUTHOR]

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A high‐performance Au@MIL‐101/PMMA/DT surface‐enhanced Raman scattering (SERS) substrate was fabricated for sensitive and stable detection of paraquat by self‐assembling metal organic framework–modified Au nanoparticles (Au@MIL‐101) on a poly(methyl methacrylate) (PMMA) film and then immobilizing the formed substrate onto a duct tape (DT). The highly closely packed Au@MIL‐101 array provided intensive hotspots for SERS sensing. The MIL‐101 layer modified on the surface of Au nanoparticles could absorb paraquat to the electromagnetic enhancement area of Au nanoparticles. The DT on the bottom made the substrate smoother, which is beneficial for achieving a more stable detection performance. As a result, the constructed substrate exhibited outstanding uniformity with relative standard deviations of 9.47% and storage stability for 2 months. For detecting paraquat, the substrate showed a low detection limit of 7.1 × 10−9 M (1.83 µg/kg) and wide linear range from 10−8 to 10−2 M. Furthermore, the substrate showed good detection performance in real cereal samples with desirable recovery rates from 91.57% to 102.32%. [ABSTRACT FROM AUTHOR]

Lyotropic liquid crystals (LLCs) produced by the self-assembly of surfactant in water represent an important class of highly ordered soft materials that have a wide range of applications. This study investigates the LLCs formed by a zwitterionic surfactant (tetradecyldimethylaminoxide, C14 DMAO) in water. The organization of C14 DMAO within the LLCs was determined based on a detailed analysis of small-angle X-ray scattering measurements and polarized microscopy observations of a typical sample. Additional to the singe-phase region, which has a hexagonal organization, several two-phase regions were observed, exhibiting the coexistence of hexagonal/ cubic, cubic/lamellar, and hexagonal/lamellar phases. The phase behavior showed an obvious dependence on temperature, with more pronounced two-phase regions at lower temperatures. Using the LLCs as a matrix, Au nanospheres, nanoellipsoids, and nanorods were prepared without requiring additional reducing reagents. These three- and one-dimensional Au nanomaterials could be converted to two-dimensional plates via the introduction of a small amount of cationic surfactant to the LLCs, such as cetyltrimethylammonium bromide (CTAB) and 1-hexadecyl-3-methylimidazolium bromide ([C16 MIm]B), which showed pronounced surface-enhanced Raman scattering activity towards solid rhodamine. The LLCs loaded with CTAB (or [C16 MIm]B) and HAuCl4 exhibited slightly different structures and mechanical strength from the original LLCs, thereby forming a new class of highly crowded colloidal materials. [ABSTRACT FROM AUTHOR]

Solar-to-steam (STS) generation based on plasmonic materials has attracted significant attention as a green method for producing fresh water. Herein, a simple in situ method is introduced to fabricate Au nanoparticles (AuNPs) on cellulose filter papers as dual-functional substrates for STS generation and surface-enhanced Raman spectroscopy (SERS) sensing. The substrates exhibit 90% of broadband solar absorption between 350 and 1800 nm and achieve an evaporation rate of 0.96 kg·m−2·h−1 under 1-sun illumination, room temperature of 20 °C, and relative humidity of 40%. The STS generation of the substrate is stable during 30 h continuous operation. Enriched SERS hotspots between AuNPs endow the substrates with the ability to detect chemical contamination in water with ppb limits of detection for rhodamine 6G dye and melamine. To demonstrate dual-functional properties, the contaminated water was analyzed with SERS and purified by STS. The purified water was then analyzed with SERS to confirm its purity. The developed substrate can be an improved and suitable candidate for fresh water production and qualification. [ABSTRACT FROM AUTHOR]

Designing high‐efficiency surface‐enhanced Raman scattering (SERS) substrates has attracted explosive attention in recent decades for their novel and potential applications. Great achievements have been made to optimize the intrinsic activity of nanomaterial in SERS substrates, while little attention has been paid to the unique structural design of the nanomaterial building blocks. Herein, a new strategy is provided for assembling Au nanoparticles into well‐defined ordered structures by using a highly ordered arrangement nanowires template to explore the ordering effect on the SERS performance. The highly ordered Au nanoparticle arrays show a detection limit of 10−9 m that exceeds disordered Au particles by two orders of magnitude, as well as over treble enhancement factor at the same detection concentration. Importantly, this novel scientific discovery can be further confirmed in various probed molecules or nanoparticles with different diameters, which means SERS substrate design can be pushed forward further combined with traditional intrinsic activity design. [ABSTRACT FROM AUTHOR]

Surface-enhanced Raman scattering is a powerful sensing tool effectively and rapidly to detect chemicals in environmental monitoring and food safety. Textile fiber-based surface-enhanced Raman scattering substrates have been fabricated to contribute to the practical applications of surface-enhanced Raman scattering sensing. Inspired by the metallic nanostructures with dense plasmonic hotspots which have excellent surface-enhanced Raman scattering activity, coarse silver layer coated nylon fibers are used in this study to combine with gold nanoparticles by a simple immersion method forming enriched plasmonic hotspots on textile fibers for ultrasensitive surface-enhanced Raman scattering detection. The fiber-based surface-enhanced Raman scattering substrate denoted as gold nanoparticle@silver layer coated nylon fiber shows a high sensitivity to rhodamine 6G with an excellent enhancement factor of 2.41 × 1010 and a detection limit of 10−14 M. The finite-difference time-domain simulations indicate that ultra-high sensitivity arises from the enhanced electric fields densely formed in the inter-particle and particle-film gap in the twisted gold nanoparticle@silver layer coated nylon fiber structure. In addition, the gold nanoparticle@silver layer coated nylon fiber substrate demonstrates outstanding surface-enhanced Raman scattering signal reproducibility (relative standard deviation 6.14%) as well as application flexibility. Through a simple swab procedure, gold nanoparticle@silver layer coated nylon fibers absorb rhodamine 6G molecules on apple and the detection limit can reach 10−13 M. Our results allowed us to foresee the use of synthetic fibers enriched with plasmonic hotspots in ultrasensitive wearable sensors. [ABSTRACT FROM AUTHOR]

[Display omitted] Microtaggant technologies for on-dose authentication have garnered significant interest for use in the anti-counterfeit activities and traceability of pharmaceutical dosage forms. Previously, we proposed a stealth nanobeacon (NB) comprising self-assembled colloidal gold nanoparticles with reporter molecules that demonstrated characteristic surface-enhanced Raman scattering (SERS) activity. However, the integration of such microtaggants into standard production lines remains underexplored. In this study, we demonstrate the incorporation of NB into tablet coatings using a simple mixing method with conventional coating solutions. Rapid and discernible SERS responses from the NB-coated tablets were observed in response to laser excitation at 785 nm for 0.1s, implying that it is an advanced and efficient method for counterfeit detection. In addition, the SERS intensity of NB increased with coating time, suggesting that NB can be used as a tracer for the real-time monitoring of coating thickness. Furthermore, NB-coated tablets were indistinguishable from NB-free tablets, even during colorimetric analysis. These results suggest that the NB possesses stealth properties and can be easily incorporated into counterfeit detection products. [ABSTRACT FROM AUTHOR]

As an ultrasensitive detection technique, the surface enhanced Raman scattering (SERS) has been widely used to identify various molecules. And triangular nanostructures have attracted attention because of their sharp corners that produce a strong SERS enhancement effect. In this paper, the Au/Ag triangular nanosheets (TNSs) were obtained by electrochemical depositing the Ag TNSs on the laser-deposited Au nuclei to expand the SERS effect. The SERS spectra of Au/Ag TNSs for the rhodamine 6 G (R6G) molecule showed a highest enhancement factor of 1.9 × 109 with a maximum relative standard deviation of 9.4 %, proving the extraordinary potential of this substrate. In the practical applications, the Au/Ag TNSs have successfully detected the food colorant (brilliant blue) at a low concentration of 10−8 M. The high-performance SERS substrate of triangular Au/Ag nanostructure would allow new opportunities in various areas utilizing SERS technique. [Display omitted] • The Au/Ag triangular nanosheets (TNSs) were obtained by deposition Ag on the laser-deposited Au nuclei. • The SERS spectra of Au/Ag TNSs for the rhodamine 6 G (R6G) molecule show a highest enhancement factor. • The Au/Ag TNSs have successfully detected the food colorant and pesticide residue at a low concentration. [ABSTRACT FROM AUTHOR]

In view of the serious harm and widespread pollution caused by deoxynivalenol (DON), it is crucial to quantify its presence in the food safety assessment process. Here, we designed a core-shell-satellite nano assembly structure as a probe, composed of an anisotropic AuNR@Ag core, an ultra-thin SiO 2 layer and a high surface coverage AuNPs satellites, which showed outstanding SERS activity and high stability. Anti-DON antibodies were modified on the surface of the prepared core-shell-satellite nano-assembly structure as SERS immunoprobe for DON specific detection using SERS-based lateral flow immunoassay (LFIA) with the advantages of simplicity, rapidity, and high sensitivity. Under optimal conditions, the detection limit for detecting DON using the SERS-LFIA method was 0.053 fg/mL, and the linear detection ranged from 0.1 fg/mL to 1 μg/mL. The SERS-LFIA strips based on AuNR@Ag@SiO 2 -AuNP nanostructures demonstrated the great potential for quick quantitative DON detection, providing a reference for trace detection of highly toxin mycotoxins. • Core-shell-satellite nanoassemblies were prepared as highly SERS-active probes. • The nanoassembly was developed for lateral flow immunoassay to detect deoxynivalenol. • This method offers a detection range of 0.1 fg/mL to 1 μg/mL for deoxynivalenol. • The limit of detection for this method is 0.053 fg/mL for deoxynivalenol. [ABSTRACT FROM AUTHOR]

While significant progress has been made to clarify the effects of Au and Ag nanoparticle size on SERS enhancement, research on the size effects of copper nanoparticles and copper-related nanoalloys on SERS enhancement remain scarce. Nanoscale copper (Cu) is important because of its unique sensing and catalytic properties; however, research on its size and compositional effects remains a significant challenge because of the intricate fabrication process and difficulty in preventing oxidation. Our study elucidated the size-dependent, surface-enhanced Raman scattering (SERS) of Cu NPs, particularly the sensing capabilities of both electromagnetic (EM) SERS at 1.5 × 103 and chemical enhancement (CE) SERS at 3.6 × 104 of approximately 58 nm Cu NPs. Additionally, a solution aging examination revealed preservation of the metal-related core structure, surface plasmon resonance, and SERS features of the PSMA/ONPG-coated Cu NPs for up to 7 days. With the introduction of galvanic replacement reactions and laser ablation syntheses, the incorporation of Au atoms enabled the fabrication of 7–75 nm Au x Cu y nanoparticles by using the remaining Cu core after aging in water, which offered precise control over the Cu/Au ratio from 5/95 to 29/71. SERS measurements of the large Au x Cu y nanoparticles amplified up to 1.4 × 104 of the EM-mediated vibrational signals from the adsorbed molecules. The strong Au–S chemical bonds of the Au-rich Au x Cu y nanocrystals increased the CE SERS to 5.5 × 104, whereas the Au 3 Cu 1 crystals at the Au x Cu y interface decreased the CE SERS but improved the electron transfer for catalysis via SERS detection. Our research provides further insight into the structural and size effects of Cu and AuCu alloys used as SERS enhancers and offers avenues for designing cutting-edge SERS catalytic sensors tailored to Cu-related catalytic reactive structures. For the first time, we also manipulated the Cu atomic structure and surface composition to understand the significance of surface effects on SERS substrates of the Cu series from a nanoscale analytical perspective. This study designed a wet chemistry approach and its combination with laser ablation to synthesize 13–75 nm copper nanoparticles and 7–75 nm Au x Cu y nanoparticles. The surface-enhanced Raman scattering effect and interfacial catalysis of Cu-based nanomaterials were investigated in terms of their size/surface properties' electromagnetic and chemical field enhancements. [Display omitted] • Highly stable and size-tunable Cu nanoparticles synthesized via combined aging reactions. • With significant improvements on SERS at approximately 58 nm of Cu nanoparticles for up to 7 days. • Galvanic replacement/laser ablation syntheses to fabricate Au x Cu y nanoparticles for size-dependent SERS enhancement. • Au-rich surface of AuCu nanomaterials provides appropriate chemical effect-SERS functionality. • Interfacial catalysis with ∼30 % Au 3 Cu 1 crystals facilitated the efficient hydrogenation from 4-NTP to 4-ATP. [ABSTRACT FROM AUTHOR]

Dual-mode signal output platforms have demonstrated considerable promise due to their improved anti-interference capability and inherent signal self-correction. Nevertheless, traditional discrete-distributed signal probes often encounter significant drawbacks, including limited mass transfer efficiency, diminished signal strength, and instability in intricate biochemical environments. In response to these challenges, a scalable and hyper-compacted 3D DNA nanoplatform resembling "periodic focusing heliostat" has been developed for synergistically enhanced fluorescence (FL) and surface-enhanced Raman spectroscopy (SERS) biosensing of miRNA in cancer cells. Our approach utilized a distinctive assembly strategy integrating gold nanostars (GNS) as fundamental "heliostat units" linked by palindromic DNA sequences to facilitate each other hand-in-hand cascade alignment and condensed into large scale nanostructures. This configuration was further augmented by the incorporation of gold nanoparticles (GNP) via strong Au–S bonds, resulting in a sturdy framework for improved signal transduction. The initiation of this assembly process was mediated by the hybridization of dsDNA to miRNA-21, which served as a primer for polymerization and nicking reactions, thus generating a multifunctional T2 probe. This probe is intricately designed with three distinct parts: a 3′-palindromic end for structural integrity, a central region for capturing SERS-active probes (Cy3-P2), and a 5′-segment for attaching fluorescence reporters. Upon integration T2 into the GNS-based heliostat unit, it promotes palindromic arm-induced aggregation and plasma exciton coupling between plasma nanoparticles and signal transduction tags. This clustered arrangement creates a high-density "hot spot" array that maximizes the local electromagnetic fields necessary for enhanced SERS and FL response. This superstructure supports enhanced aggregation-induced signal amplification for both SERS and FL, offering exceptional sensitivity with LOD as low as 0.0306 pM and 0.409 pM. The efficacy of this method was demonstrated in the evaluation of miRNA-21 in various cancer cell lines. • A new concept of improving dual-mode signal output via aggregation-induced spatiotemporally confined effect is proposed. • A scalable and highly compacted 3D DNA nanoplatform was created for intracellular microRNA detection. • Utilizing multi-branch gold nanostars and palindromic DNA, the aggregation-induced plasmon-exciton coupling can be achieved. • This approach allows for precise evaluation of miRNA-21 in different cancer cells. [ABSTRACT FROM AUTHOR]

Uric acid (UA), the final metabolite of purine, is primarily excreted through urine to maintain an appropriate concentration in the bloodstream. However, any malfunction in this process can lead to complications due to either deficiency or excess amount of UA. Hence, the development of a sensor platform with a wide-range detection is crucial. To realize this, we fabricated a surface-enhanced Raman spectroscopy (SERS) substrate inspired by a type of starfish with numerous protrusions, Asterias forbesi. The Asterias forbesi-inspired SERS (AF-SERS) substrate utilized an Au@Ag nanostructure and gold nanoparticles to mimic the leg and protrusion morphology of the starfish. This substrate exhibited excellent Raman performance due to numerous hotspots, demonstrating outstanding stability, reproducibility, and repeatability. In laboratory settings, we successfully detected UA down to a concentration of 1.16 nM (limit of detection) and demonstrated selectivity against various metabolites. In the experiments designed for real-world application, the AF-SERS substrate detected a broad range of UA concentrations, covering deficiencies and excesses, in both serum and urine samples. These results underscore the potential of the developed AF-SERS substrate as a practical detection platform for UA in real-world applications.

Grain crops are easily contaminated by fungi due to the existence of various microorganisms in the storage process, especially in humid and warm storage conditions. Compared with conventional methods, surface-enhanced Raman scattering (SERS) has paved the way for the detection of fungi in grain crops as it is a rapid, nondestructive, and sensitive analytical method. In this work, Aspergillus niger, Saccharomyces cerevisiae, Fusarium moniliforme and Trichoderma viride in grain crops were detected using colloidal Au nanoparticles and SERS. The results indicated that different fungi showed different Raman phenotypes, which could be easily characterized by SERS. Combined with multivariate statistical analysis, identification of a variety of fungi could be accomplished rapidly and accurately. This research can be applied for the rapid detection of fungi in the food and biomedical industries. [ABSTRACT FROM AUTHOR]

The formation of well‐defined, functional surfaces that incorporate the unique properties of inorganic nanoparticles (NPs) requires robust and scalable fabrication strategies. Herein, we report a methodology for the decoration of polymer molds with plasmonic (gold) nanoparticle arrays. Wrinkled soft templates were used to assemble gold NPs (74 nm) into line arrays. These pre‐formed nanoparticle arrays were transferred in a subsequent step onto polycarbonate molds via an injection molding process. Scanning electron microscopy analysis revealed the structural fidelity of the pattern structure upon transfer. The preservation of the optical functionality of the gold nanoparticle line arrays was proven by surface‐enhanced Raman scattering (SERS) experiments. The reported strategy of nanoparticle pattern transfer to polymer bodies by this robust process is expected to prove useful for the fabrication of polymer surfaces with tailored optical functionality. [ABSTRACT FROM AUTHOR]

Antibiotics have brought many benefits to public health systems worldwide since their first use in the last century, yet with their overuse in clinical treatment and livestock farming, new public health issues have arisen. Previously, we found in our experiments that the levels of macB genes in bovine raw milk ranked among the top of many drug resistance genes. In this paper, we present an analysis of regularly interspaced clustered short palindromic repeats (CRISPR) combined with surface-enhanced Raman scattering (SERS) technology for the detection of the drug resistance gene macB. The analysis was accomplished through the collaboration of the CRISPR system's ability to specifically identify genes and the more sensitive performance of the SERS. The analysis detects the drug resistance gene macB and does not yet require complex steps such as nucleic acid amplification. This method may prove to be an effective method for accurate detection of the drug-resistant gene macB, thus enabling more effective prevention of contamination of drug-resistant genes in food hygiene. [ABSTRACT FROM AUTHOR]

The spontaneous self-assembly of metal nanocrystals into two-dimensional (2D) monolayer superlattices with highly ordered symmetry and configuration paves the way towards the fabrication of functional materials. However, there remains great challenge for anisotropic nanocrystals to self-assembly into high quality superlattice because of the orientation and configuration consistency. Here, a facile yet universal solvent annealing driven 2D interfacial assembly of synthetic dried metal nanocrystals is firstly developed to realize the construction of the non-close-packing 2D monolayer gold nanocube (AuNC) superlattice with tunable interparticle distance and internal configurations (i.e. face-to-face and hexagonally-packed arrangement), which is achieved by precisely controlling molecular weight of polymer ligands tethered on AuNCs and the van der Waals forces between the adjacent AuNCs. In addition, the scale of the generated 2D monolayer AuNC superlattice with highly ordered internal arrangement and orientation can reach up to hundreds of micrometers, thus acquiring significant surface-enhanced Raman scattering performance of the large scale superlattice due to the strong plasma coupling effect. This strategy not only provides a robust route to fabricate nanocrystal superlattice structures but also offers a promising platform for preparing diverse functional materials with potential applications in electronics, photonics, detections, and others. [ABSTRACT FROM AUTHOR]

The biochemical composition of sweat is closely related to the human physiological state, which provides a favorable window for the monitoring of human health status, especially for the athlete. Herein, an ultra-simple strategy based on the surface-enhanced Raman scattering (SERS) technique for sweat analysis is established. Metal–phenolic network (MPN), an outstanding organic-inorganic hybrid material, is adopted as the reductant and platform for the in situ formation of Au-MPN, which displays excellent SERS activity with the limit of detection to 10−15 M for 4-mercaptobenzoic acid (4-MBA). As an ultrasensitive SERS sensor, Au-MPN is capable of discriminating the molecular fingerprints of sweat components acquired from a volunteer after exercise, such as urea, uric acid, lactic acid, and amino acid. For pH sensing, Au-MPN/4-MBA efficiently presents the pH values of the volunteer's sweat, which can indicate the electrolyte metabolism during exercise. This MPN-based SERS sensing strategy unlocks a new route for the real-time physiological monitoring of human health. [ABSTRACT FROM AUTHOR]

Plasmonic polycrystals composed of loosely packed plasmonic nanoparticles formed microscale plasmonic grains with random orientations may exhibit interesting optical properties. Their fabrication includes placing nanoparticles in order to form plasmonic grains and forming the random orientation of the plasmonic grains. The seemingly mutually exclusive nanoparticle ordering and random grain orientation processes challenge existing technologies. Here a self‐assembled bowl‐in‐bowl template‐confined dewetting process to prepare plasmonic polycrystals is developed. The size and composition of the plasmonic nanoparticles can be conveniently designed before experiments, which are inaccessible to conventional fabrication methods. Complex plasmonic coupling between the Au nanoparticles and the plasmonic grains within the plasmonic polycrystals is observed. The microbowls further endow plasmonic nanostructures with more interesting optical properties arising from multiple scattering processes within the concave bowl surfaces. The broadband response of the plasmonic polycrystals makes them active under 532, 633, and 785 nm laser excitation for surface‐enhanced Raman scattering (SERS) sensing applications. Finite‐difference time‐domain simulations are performed to explain the optical properties of the plasmonic polycrystals and the SERS enhancement. The simple template‐confined dewetting process provides a powerful approach to design plasmonic polycrystals with application potentials in plasmonic, sensing, and photonic fields. [ABSTRACT FROM AUTHOR]

Aspergillus flavus and Aflatoxins in grain crops give rise to a serious threat to food security and cause huge economic losses. In particular, aflatoxin B1 has been identified as a Class I carcinogen to humans by the International Agency for Research on Cancer (IARC). Compared with conventional methods, Surface-Enhanced Raman Scattering (SERS) has paved the way for the detection of Aspergillus flavus and Aflatoxins in grain crops as it is a rapid, nondestructive, and sensitive analytical method. In this work, the rapid detection of Aspergillus flavus and quantification of Aflatoxin B1 in grain crops were performed by using a portable Raman spectrometer combined with colloidal Au nanoparticles (AuNPs). With the increase of the concentration of Aspergillus flavus spore suspension in the range of 102–108 CFU/mL, the better the combination of Aspergillus flavus spores and AuNPs, the better the enhancement effect of AuNPs solution on the Aspergillus flavus. A series of different concentrations of aflatoxin B1 methanol solution combined with AuNPs were determined based on SERS and their spectra were similar to that of solid powder. Moreover, the characteristic peak increased gradually with the increase of concentration in the range of 0.0005–0.01 mg/L and the determination limit was 0.0005 mg/L, which was verified by HPLC in ppM concentration. This rapid detection method can greatly shorten the detection time from several hours or even tens of hours to a few minutes, which can help to take effective measures to avoid causing large economic losses. [ABSTRACT FROM AUTHOR]

Gold nanoparticles (AuNPs) and their composites have been applied in surface-enhanced Raman scattering (SERS) detection methods, owing to their stable and excellent surface plasmon resonance. Unfortunately, methods for synthesizing AuNPs often require harsh conditions and complicated external steps. Additionally, removing residual surfactants or unreacted reductants is critical for improving the sensitivity of SERS detection, especially when employing AuNPs-assembled multidimensional substrates. In this study, we propose a simple and green method for AuNPs synthesis via photoreduction, which does not require external surfactant additives or stabilizers. All the processes were completed within 20 min. Along this way, only methanol was employed as the electron acceptor. Based on this photoreduction synthesis strategy, AuNPs can be directly and circularly assembled in situ in multidimensional substrates for SERS detection. The removal of residual methanol was easy because of its low boiling point. This strategy was employed for the preparation of three different dimensional SERS substrates: filter paper@AuNPs, g-C3N4@AuNPs, and MIL-101(Cr)@AuNPs. The limit of detection of filter paper@AuNPs for thiabendazole SERS detection was 1.0 × 10−7 mol/L, while the limits of detection of g-C3N4@AuNPs and MIL-101(Cr)@AuNPs for malachite green SERS detection were both 5.0 × 10−11 mol/L. This strategy presents potential in AuNP doping materials and SERS detection. [ABSTRACT FROM AUTHOR]