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In this work, filter paper was used as a low cost substrate for silver nanoparticles in order to perform the detection and quantification of acetylsalicylic acid by SERS in a commercial tablet. The reaction conditions were 150mM of ammonium hydroxide, 50mM of silver nitrate, 500mM of glucose, 12min of the reaction time, 45°C temperature, pretreatment with ammonium hydroxide and quantitative filter paper (1-2µm). The average size of silver nanoparticles deposited on the paper substrate was 180nm. Adsorption time of acetylsalicylic acid on the surface of the silver-coated filter paper was studied and an adsorption time of 80min was used to build the analytical curve. It was possible to obtain a calibration curve with good precision with a coefficient of determination of 0.933. The method proposed in this work was capable to quantify acetylsalicylic acid in commercial tablets, at low concentration levels, with relative error of 2.06% compared to the HPLC. The preparation of filter paper coated with silver nanoparticles using Tollen's reagent presents several advantages such as low cost of synthesis, support and reagents; minimum amount of residuals, which are easily treated, despite the SERS spectroscopy presenting fast analysis, with low sample preparation and low amount of reactants as in HPLC analysis. [ABSTRACT FROM AUTHOR]

Supported silver nanoparticles on filter paper were synthesized using Tollens' reagent. Experimental designs were performed to obtain the highest SERS enhancement factor by study of the influence of the parameters: filter paper pretreatment, type of filter paper, reactants concentration, reaction time and temperature. To this end, fractional factorial and central composite designs were used in order to optimize the synthesis for quantification of nicotinamide in the presence of excipients in a commercial sample of cosmetic. The values achieved for the optimal condition were 150mM of ammonium hydroxide, 50mM of silver nitrate, 500mM of glucose, 8min for the reaction time, 45°C temperature, pretreatment with ammonium hydroxide and quantitative filter paper (1–2µm). Despite the variation of SERS intensity, it was possible to use an adapted method of internal standard to obtain a calibration curve with good precision. The coefficient of determination of the linear fit was 0.97. The method proposed in this work was capable of quantifying nicotinamide on a commercial cosmetic gel, at low concentration levels, with a relative error of 1.06% compared to the HPLC. SERS spectroscopy presents faster analyses than HPLC, also complex sample preparation and large amount of reactants are not necessary. [ABSTRACT FROM AUTHOR]

For the past few years, sweat analysis for health monitoring has attracted increasing attention benefiting from wearable technology. In related research, the sensitive detection of uric acid (UA) in sweat with complex composition based on surface-enhanced Raman spectroscopy (SERS) for the diagnosis of gout is still a significant challenge. Herein, we report a visualized and intelligent wearable sweat platform for SERS detection of UA in sweat. In this wearable platform, the spiral channel consisted of colorimetric paper with Ag nanowires (AgNWs) that could capture sweat for SERS measurement. With the help of photos from a smartphone, the pH value and volume of sweat could be quantified intelligently based on the image recognition technique. To diagnose gout, SERS spectra of human sweat with UA are collected in this wearable intelligent platform and analyzed by artificial intelligence (AI) algorithms. The results indicate that the artificial neural network (ANN) algorithm exhibits good identification of gout with high accuracy at 97%. Our work demonstrates that SERS-AI in a wearable intelligent sweat platform could be a feasible strategy for diagnosis of gout, which expands research on sweat analysis for comfortable and noninvasive health monitoring. [ABSTRACT FROM AUTHOR]

Silver nanoparticles decorated drawing paper (AgNPs-drawing paper) substrates were prepared by robotic writing technique. The AgNPs-drawing paper exhibited high sensitivity, reproducibility and stability. And the detection limit for malachite green adsorbed on AgNPs-drawing paper substrates was as low as 10−18 mol/L. [Display omitted] • The AgNPs-drawing paper substrates were fabricated by robotic writing approach. • The detection limit for malachite green adsorbed on the substrates was 10−18 mol/L. • The Raman enhancement factor of the substrate was calculated to be 1015. • The substrates had good reproducibility and uniformity with RSD less than 10%. • The AgNPs-drawing paper substrates exhibited long-term stability during six months. Inspired by hand writing approach for preparing surface-enhanced Raman scattering (SERS) substrates, silver nanoparticles (AgNPs) decorated drawing paper substrates were prepared by robotic writing technique. The wettabilities and surface morphologies of the drawing paper before and after the deposition of AgNPs were characterized by contact angle analyzer and scanning electron microscope, respectively. Malachite green was employed as a probe molecule to evaluate the SERS activities of the AgNPs-drawing paper substrates. The AgNPs-drawing paper substrates exhibited extremely high sensitivity that the detection limit for malachite green was down to 10−18 mol/L and the Raman enhancement factor was calculated to be 1015. The relative standard deviation (RSD) values of the Raman peaks intensities collected from twelve points on a single substrate and fifteen substrates were used to evaluate the uniformity and reproducibility of the AgNPs-drawing paper substrates. It was found that the substrates had good reproducibility and uniformity with RSD values of 7.29% and 9.70%, respectively. Furthermore, the prepared AgNPs-drawing paper substrates exhibited long-term stability among six months. [ABSTRACT FROM AUTHOR]

The document is a contents list for the journal "Analyst" published by the Royal Society of Chemistry. It includes a range of articles and papers on various topics related to chemistry and chemical sciences. Some of the topics covered include fluorescent carbon dots, metal nanoparticles, biosensing systems, nanoplastic detection, and electrochemical analysis. The journal aims to connect the global chemistry community and reinvest its profits back into the field. [Extracted from the article]

Practical human biofluid sensing requires a sensor device to differentiate patients from the normal group with high sensitivity and specificity. Label-free molecular identification from human biofluids allows direct classification of abnormal samples, providing insights for disease diagnosis and finding of new biomarkers. Here, we introduce a label-free surface-enhanced Raman scattering sensor based on a three-dimensional plasmonic coral nanoarchitecture (3D-PCN), which has strong electromagnetic field enhancement through multiple hot spots. The 3D-PCN was synthesized on a paper substrate via direct one-step gold reduction, forming a coral-like nanoarchitecture with high absorption property for biofluids. This was fabricated as a urine test strip and then integrated with a handheld Raman system to develop an on-site urine diagnostic platform. The developed platform successfully classified the human prostate and pancreatic cancer urines in a label-free method supported by two types of deep learning networks, with high clinical sensitivity and specificity. Our technology has the potential to be utilized not only for urinary cancer diagnosis but also for various human biofluid sensing systems as a future point-of-care testing platform. [Display omitted] [ABSTRACT FROM AUTHOR]

Rapid and point-of-need (PON) detection of bacteria is crucial to directly provide rapid and reliable diagnostics information during on-site tests, allowing more room for taking proactive measures. By taking the multifaceted advantages of CRISPR/Cas12a and surface-enhanced Raman scattering (SERS), for the first time, we designed a recombinase polymerase amplification (RPA)-integrated microfluidic paper-based analytical device (μPAD), coined RPA-Cas12a-μPAD for supersensitive SERS detection. Single-stranded DNAs were designed to "pull down" SERS nanoprobes. The amplicons of the invA gene triggered the trans -cleavage of Cas12a, resulting in the indiscriminate shredding of linker ssDNA. Thus, the degree of aggregation of SERS nanoprobes was dependent on the concentration of Salmonella typhimurium (S. typhi), which was determined on a μPAD and monitored by a Raman spectrometer. The limit of detection for S. typhi was approximately 3–4 CFU/mL for spiked milk and meat samples with a dynamic detection range from 1 to 108 CFU/mL. The RPA-Cas12a-μPAD secured accurate tests for food samples in 45 min. This work expands the reach of CRISPR-based diagnostics (CRISPR-Dx) and provides a novel and robust bacterial PON detection platform. [Display omitted] • For the first time, a recombinase polymerase amplification-integrated microfluidic paper-based analytical device (μPAD) was fabricated for SERS detection of pathogenic bacteria. • It was able to supersensitive, specific and quantitative detection of Salmonella typhimurium in less than 45 min. • It was capable of Salmonella typhimurium detection in real food samples, which was comparable or better than the most reported methods. [ABSTRACT FROM AUTHOR]

Surface-enhanced Raman spectroscopy (SERS) enables multiplex detection of analytes using simple, portable equipment consisting of a single excitation source and detector. Thus, in theory, SERS is ideally suited to replace fluorescence in assays that screen for numerous deoxyribonucleic acid (DNA) targets, but in practice, SERS-based assays have suffered from complexity and elaborate processing steps. Here, we report an assay in which a simple inkjet-fabricated plasmonic paper device enables SERS-based detection of multiple DNA targets within a single polymerase chain reaction (PCR). In prior work, we demonstrated the principles of chromatographic separation and SERS-based detection on inkjet-fabricated plasmonic paper. The present work extends that capability for post-PCR gene sequence detection. In this design, hydrolysis DNA probes with 5′ Raman labels are utilized; if the target is present, the probe is hydrolyzed during PCR, freeing the reporter. After applying the PCR sample to a paper SERS device, an on-device chromatographic separation and concentration is conducted to discriminate between hydrolyzed and intact probes. SERS is then used to detect the reporter released by the hydrolyzed probes. This simple separation and detection on paper eliminates the need for complex sample processing steps. In this work, we simultaneously detect the methicillin-resistant Staphylococcus aureusgenes mecAand femBto illustrate the concept. We envision that this approach could contribute to the development of multiplex DNA diagnostic tests enabling screening for several target sequences within a single reaction, which is necessary for cases in which sample volume and resources are limited. [ABSTRACT FROM AUTHOR]

The document is a contents list for the journal "Analyst" published by the Royal Society of Chemistry. It includes a range of articles and papers on various topics related to chemistry and scientific research. Some of the topics covered include the selection of aptamers against SARS-CoV-2, insights into lipid and fatty acid metabolism, and non-invasive diagnostic tests for lung cancer. The journal also offers information on training courses and events for professional development in the field of chemistry. [Extracted from the article]

Lotus leaf is a super-hydrophobic material found in nature. Drawing inspiration from the micro-nano structure of lotus leaf surface, a hybrid surface-enhanced Raman spectroscopy (SERS) substrate owning both hydrophobic and hydrophilic properties was developed. The biomimetic part, which was fabricated by replicating the surface structure of lotus leaf using polydimethylsiloxane, exhibited a hydrophobic surface with a contact angle of 150.3°. Meanwhile, silver nanoparticles-coated filter paper was assembled on the top of the biomimetic part to render hydrophilic regions for SERS detection. Silver nanoparticles on the surface of filter paper owned a size of approximately 70–80 nm with an interval of about 5–10 nm. The hydrophobic/hydrophobic hybrid regions on the substrate significantly enhanced Raman signals of rhodamine 6g with mitigated coffee ring effects, showing a limit of detection low to 10−10 M. Notably, the limit of detection of this technique for thiram on apple surface reached 0.5 ng/cm2, which was lower than the reported methods. The prepared substrate displayed exceptional uniformity and stability, with an RSD value of 7.21% calculated based upon 30 randomly selected Raman signals, and experienced a decrease in signal by only 29.7% after 30-d storage. This biomimetic substrate can be utilized for batch detection of pesticide residues on fresh produce with high sensitivity, thereby owning great potential for application as a rapid detection tool for food safety. [ABSTRACT FROM AUTHOR]

Highlights: [•] AuNPs on paper were functionalized to develop SERS biodiagnostic platform. [•] Reproducible SERS spectra of antibody–antigen were achieved. [•] Modification of antibody structure upon antigen binding resulted in Raman shifts. [•] SERS intensity increased as a function of antigen concentration. [ABSTRACT FROM AUTHOR]

Abstract: Paper-based SERS active substrates were prepared adsorbing spherical and star-shaped gold nanoparticles on a standard filter paper support. Besides the deposition conditions, morphological parameters of the particles were found to strongly affect the enhancer properties of the substrates. The developed substrate was tested regarding surface homogeneity as well as in the quantitative analysis of malachite green, – a well documented Raman reporter dye – and proved to be capable also to detect the oxidation products of apomorphine, a well-known drug molecule used in Parkinson's disease. This material is simple to prepare, easy to handle and dispose and as such it could be a perfect target for further development of a new family of mass-produced, cheap solid SERS substrates. [Copyright &y& Elsevier]

Highlights: [•] An Au–Ag bimetallic microfluidic, dumbbell-shaped SERS sensors were fabricated. [•] The sensor was fabricated on cellulose paper by screen printing. [•] The sensor could enable self-filtering of fluids to remove suspended particles within wastewater without pumping. [•] The detection zone of the sensor allows sensitive SERS detection. [ABSTRACT FROM AUTHOR]

• AgNSs with various dimeters were fabricated by adjusting the amount of reducing agents (NaBH 4). • AgNSs grafted PMMA-treated paper platform were easily prepared by a one-step synthesis. • SERS ultradetection of platform was obtained 10–10 M with an EF of 1.2 × 108. • An excellent reproducibility of Raman signal with RSD of 10.39% was obtained. • An outstanding selectivity each probe molecule in an analyte mixture solution of R6G and CV at 10−8 M was achieved. The synthesis procedures and processes for evaluating the SERS performance of AgNSs grafted PMMA treated paper platform. [Display omitted] Paper-based sensing platforms have become one of the hot topics in spectroscopic technique for chemical and biological detections. However, it has been still challenging to detect molecules at trace levels owing to its intrinsic interconnected porous structures related to the fibril structure of paper and hydrophilic characteristic. Herein, a cellulose paper combined molecular polymers and hybridized chain reaction that led to hydrophobic functionalization with static water contact angles>90° for surface-enhanced Raman scattering (SERS) was proposed. During the fabrication, the formation of the ultrasensitive SERS is supported by interconnection of silver nanoparticles (NPs) of varying diameters from 20 to 50 nm and concentration in the range of 2–6 mL on one side of the paper substrate to achieve excellent quantification capability based on hotspots engineering-based clusters and analyte enrichment system, particularly, AgNPs with diameter of 30 nm exhibit the highest Raman signals at 532 nm excitation. The resulting plasmonic arrays show SERS detection of CV molecules at a low concentration of 10–10 M with an enhancement factor of 1.2 × 108 and excellent reproducibility with RSD of Raman signal as low as 10.39%. An outstanding selectivity each probe molecule in an analyte mixture solution of R6G and CV at diluted concentration (10−8 M) of the platform was obtained. These outcomes could be designated to the more target molecules trapped in the hotspots and cluster of AgNPs after activated molecular enrichment mechanism underlying hydrophobic layer correlated with natural evaporation. [ABSTRACT FROM AUTHOR]

A paper-based surface-enhanced Raman scattering (SERS) sensor that combined the excellent performance of three-dimensional (3D) dendritic gold (DAu) matrix and the selective adsorption ability of biomimetic recognition polymer (BRP) has been constructed for ultrasensitive detection of thiram. The 3D DAu structure decorated on cellulosic matrix provides predominant SERS performance and chemical stability for the analytical platform. Compared with two-dimensional (2D) SERS platforms, it can get efficient utilization of 3D laser excitation volume to achieve optimal SERS enhancement. BRP membranes for the specific recognition and enrichment of thiram were prepared by bulk polymerization. And the urchin-like nanoparticles (UNPs) with rich cutting-edge structure were decorated in the BRP to provide sufficient "hot spots". In the region where DAU was close to UNPS, the synergistic SERS enhancement was generated through particle plasmon coupling. And the whole structure of the composite multilayer provides multiple SERS enhancement for thiram detection. The SERS response of the sensor toward thiram showed excellent correlation during the range of 1 × 10−10 to 1 × 10−7 mol·L−1 with the detection limits as low as 2.75 × 10−11 mol·L−1. The test results of selectivity, reproducibility, and accuracy indicated that the paper-based DAu/BRP (UNPs) sensor possessed potential applications in pesticides analytical and other related fields. • A three-dimensional SERS sensor was developed for pesticide residue detection. • The innovative preparation of dendritic gold matrix. • A reusable SERS paper slip which with multiple signal amplification strategies. [ABSTRACT FROM AUTHOR]

Apart from being the subject of this Special Issue, what is nanometrology? Such methods are certainly "measurement science at nanoscale", and there is certainly a continuous development in them; however, the authors for some reason do not call such work "nanometrology". When looking at some older review papers related to nanometrology, e.g., [[1]], we can see that it was expected that nanometrology could cover nearly all that was mentioned above, expanding also to novel areas such as life sciences. [Extracted from the article]

SERS based immunoassays for point-of-care diagnostics are a promising tool to facilitate biomarker detection for early disease diagnosis and disease control. The technique is based on a sandwiched system in which antigen is first captured by a selective plasmonic paper substrate and then labeled by an extrinsic Raman label (ERL), consisting of a 60 nm gold nanoparticle (AuNP) functionalized with a mixed monolayer of detection antibody and 4-nitrobenezenethiol (NBT) as a Raman reporter molecule. Here, we report on the use of AuNP modified filter paper as a novel capture membrane in a vertical flow format. This vertical flow configuration affords reproducible flow of sample and label through the capture substrate to overcome diffusion limited kinetics and significantly reduced assay time. The filter paper was selected due to its affordability and availability, while the embedded AuNPs maximized plasmonic coupling with the ERLs and SERS enhancement. Additionally, the embedded AuNP served as a scaffold to immobilize capture antibody to specifically bind antigen. In this work, a SERS-based rapid vertical flow (SERS-RVF) immunoassay for detection of mouse IgG was developed to establish proof-of-principle. Optimization of assay conditions led to a limit of detection of 3 ng/mL, which is comparable to more traditional formats carried out in multi-well plates, and significantly reduced assay time to less than 2 min. Additionally, IgG was accurately quantified in normal mouse serum to validate the SERS-RVF assay for application to the analysis of biological samples. These results highlight the potential advantages of the SERS-RVF platform for point-of-need testing. Image 1 • SERS-based rapid vertical flow (RVF) immunoassay for point-of-care testing. • Plasmonic paper capture substrate facilitates plasmonic coupling with SERS-active label to enhance sensitivity. • Confirmed analytical capabilities by quantification of protein in blood serum. [ABSTRACT FROM AUTHOR]

• A micro size paper-based sensor for tartrazine detection was developed. • Biomimetic recognizer was applied in combination with sensitive SERS detection. • Sandwich type SERS sensor based on AgNPs and biomimetic recognizer was realized. A paper-based surface enhanced Raman scattering (SERS) sensor with synergistic enhancement strategy for selective detection of tartrazine in food products has been established in this work. For economic and mass production purposes, paper substrates were firstly installed with a silver layer to endow the paper with electroconductibility and dense plasmonic hotspots. A biomimetic recognizer (BR) membrane was attached upon the Ag paper as specific identification device, and a layer of high-density of silver nanoparticles (AgNPs) was decorated on the surface of Ag/BR paper through in-situ growth method to form a sandwich structure. Since the double layer of Ag/AgNPs demonstrated excellent local plasma resonance effect, combined with the identification function of BR, it made the paper SERS sensor emerge incredible Raman synergistic enhancement response on tartrazine molecules embraced the plasma nanoparticles. Thus, the synergistically enhanced Ag/BR/AgNPs paper SERS sensor was achieved and applied in on-site test of tartrazine in Children's snacks. The linear range (0.3∼10 μg mL−1) and the limit of detection (0.1138 μg mL−1) of the SERS paper strip could be applied as a screening or occupational cut-off of tartrazine (100 μg mL−1) for reference. In addition, the proposed paper sensor can be a potential candidate for multicomponent screening and is suitable for mass production and promotion. [ABSTRACT FROM AUTHOR]

Highlights: [•] Inkjet-printed paper-based SERS is a new method for low-cost chemical detection. [•] The devices are optimized for low-cost easy-to-use chemical detection in the field. [•] We demonstrate detection of 1.8ppb BPE on an inkjet-printed SERS device. [•] We detect trace concentrations of fungicide in water with a paper SERS dipstick. [•] We use the flexible SERS devices as swabs to detect trace residue of a fungicide. [ABSTRACT FROM AUTHOR]

• A paper SERS aptasensor for okadaic acid monitoring has been proposed. • Composite resonance bilayer was facilely manufactured in-situ on the paper swab. • Dense AuNPs and 3D succulent-like silver constituted the multiple enhanced bilayers. • Self-designed aptamer were equipped to establish specific capture interface. • Silver nano-octahedra constituted the third enhancement stage. Okadaic acid (OA) is the main toxic component of diarrhetic shellfish poisoning, which can cause vomiting, diarrhea, and even induce tumor formation in people who accidentally ingest it. To strengthen the front-end prevention and control of shellfish safety, a surface-enhanced Raman scattering (SERS) paper swab based on high-affinity binding and high-specific recognition performance of nucleic acid aptamer was proposed to detect OA by virtue of enhanced multistage plasmon coupling effect. Composite resonance bilayer constituted by evenly dispersed gold nanoparticles integrating with a three-dimensional (3D) succulent-like silver particle was facilely manufactured in-situ on the paper substrate. Subsequently, with the assistance of 3D nanotopography structured silver nano-octahedra connected on the signal probe, a multistage SERS signal cooperative amplification platform was formed with about 10-fold enhanced Raman intensity higher than either single-layer substrate. Owning to the unique strategy of superimposed signal enhancement, such paper SERS aptasensor possessed admirable specific recognition and sensitivity has been successfully used in the on-site quantization of OA, with a detection limit of 0.31 ng/mL. Furthermore, the construction of the SERS paper swab is of great significance to the promotion of rapid on-site analysis approach of OA content in seafood by customs, seafood market supervision departments and ordinary consumers. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare three gunshot residue (GSR) collection methods used in conjunction with chemographic detection applied by different regional Swiss police services. The specimens were collected from the hands of a shooter with either filter paper (Filter method) or adhesive foil. The adhesive foil was then either applied against photographic paper during visualisation (AF Photo method) or coated with a layer of polyvinyl alcohol (AF PVAL method). The experiments involved two conditions of the examined hands, i.e. dry and humidified. The residues were revealed using the sodium rhodizonate test (SRT). Preliminary tests assessing the possibility of conducting a confirmatory Scanning Electron Microscopy coupled to Energy Dispersive X-ray spectroscopy (SEM/EDX) analysis after the chemographic test were performed on a number of specimens by cutting positive spots and mounting them on stubs. Obtained results were compared in terms of effectiveness - number of positive spots, time requirements, quality of subsequent SEM-EDX analysis, ease of use and cost. The Filter method generally yielded a high-quality detection with both dry and humidified hands, as well as a simple, quick and efficient confirmation by SEM/EDX. The AF Photo performed well on dry hands, but not on humidified hands. The AF PVAL method performance was lower compared to the other methods in both examined conditions of the hands. The SEM/EDX analysis showed that the Filter and AF PVAL method provided satisfactory results when a sufficient carbon coating thickness was applied to the cuttings. It was also observed that the thinner the PVAL layer, the better the quality of the spectra and obtained images in SEM/EDX. Furthermore, the surface of the photographic paper did not seem to be conductive, even after the application of a thick layer of carbon. In conclusion, the Filter method gave the best overall results, but its application required slightly more time and expertise than the two other methods. • The Filter method had a high-quality detection with both dry and humidified hands. • The adhesive foil with photo paper performed better on dry than humidified hands. • The adhesive with a PVAL method did not perform as well as the other methods. • Both Filter and PVAL methods provided satisfactory SEM/EDX analysis. • SEM/EDX analysis preparation was more tedious for the AF Photo and PVAL methods. [ABSTRACT FROM AUTHOR]

Surface enhanced Raman spectroscopy (SERS) provides a useful sensory platform whereby target molecules at low concentration are identified, potentially detecting a single molecule. As a result, SERS has been widely applied in a variety of research endeavors using different substrates, one of which is a cellulose-based substrate. The unique properties of cellulose in its various forms make it an important component in the design of a SERS substrate. Being a flexible substrate with minimal SERS signal interference, paper-based cellulose templates are the most extensively explored form of cellulose in SERS substrate design, with innovative designs and applications. This review provides an overview of the fundamental tools of SERS enhancement, followed by a comprehensive appraisal of the various design principles associated with producing cellulose-based materials and their use as SERS substrates. Though cellulose in its various forms cannot provide the localized surface plasmon resonance required in SERS, it aids in aggregation and stabilization of plasmonic nanoparticles leading to "hot spots" for SERS signal enhancement. The unconventional techniques adopted in the designs are examined and the associated challenges are highlighted. The review demonstrates SERS applications of the substrates in diverse technologies such as bioanalysis, water quality assessment, food safety, adulteration of illicit drugs and dye identification in artworks. Ultimately, we envisage the need for a universal set standard to realize the ideal of designing SERS substrates from the perspective of end-user demand. This can be achieved through a re-evaluation of existing findings on cellulose-based SERS substrates. [ABSTRACT FROM AUTHOR]

The rapid detection of bacterial metabolites responsible for cell communication is important for the early diagnosis of bacterial infection and treatment with appropriate antibiotics. Surface-enhanced Raman spectroscopy (SERS) has provided amplified molecular fingerprints, serving as one of the most promising nondestructive and label-free direct detection methods. However, direct analysis of complex bacterial cultures using the conventional SERS approach is difficult. Here, we design a new paper-based 3D SERS substrate and establish a facile one-pot Au electrodeposition protocol to directly detect pyocyanin, a signaling molecule of Pseudomonas aeruginosa , secreted in the culture medium, without pretreatment steps. During one-pot Au electrodeposition in the presence of an Au precursor and culture medium, the bacterial pathogen molecule (i.e. , pyocyanin) is captured in the interstitial voids of the 3D hydrogel matrix among growing Au grains, resulting in high amplification of the Raman signal intensity. Because the hydrogel skin excludes macromolecules (i.e. , proteins) in the culture medium, thereby maintaining an uncontaminated surface, our approach achieves the direct and rapid detection of pyocyanin in a complex bacteria culture sample without any purification steps. Therefore, the pyocyanin concentration during bacterial culturing is easily and directly monitored, which is important for the early diagnosis of infection and in-depth studies of bacterial cell communication. • One-pot Au electrodeposition is important for enhancing the SERS sensitivity. • Hydrogel-coated 3D Au nanostructure can detect pyocyanin. [ABSTRACT FROM AUTHOR]

• Paper-based SERS sensor was modified by Cl- to improve its sensitivity. • The SERS substrate was equipped with high reproducibility and time stability. • Fentanyl citrate in urine and serum were detected using the SERS substrate. Recently, the phenomenon of fentanyls overdose leading to death is emerging in an endless stream. There is an urgent requirement to quickly identify fentanyl content in body fluids for medical and judicial purposes. With this in mind, we present a paper-based SERS substrate decorated with uniform gold nanospheres treated by chloride ion for the detection of fentanyl citrate in urine and serum. In particular, the paper-based SERS sensor was prepared by liquid/liquid self-assembly technique and chloride ion was introduced to clean and modify the substrate surface, which improved the sensitivity of the solid substrate with an enhancement factor (EF) as high as 1.64 × 105. Moreover, the uniformity of each paper-based substrate and the repeatability on different batches of substrate were excellent, and there was no obvious change in the intensity response of Raman spectra within a month. As a result, the quantitative analysis of fentanyl citrate in artificial urine and rat serum were performed based on the modified paper-based substrate with the limit of detection as low as 0.59 μg/mL and 2.78 μg/mL, respectively. Both the concentrations of the two biological samples with the Raman signal intensity were linearly plotted and the recovery of the spiked samples with different concentrations was collected to verify the accuracy of the quantitative curves. All the results suggest that this work makes SERS method available for the rapid identification and quantitative analysis of illicit drug in the real biological samples. [ABSTRACT FROM AUTHOR]

Currently colorimetric paper lateral flow strips (PLFS) encounter two major limitations, that is, low sensitivity and severe interference from complex sample matrices such as blood. These shortcomings limit their application in detection of low-concentration analytes in complex samples. To solve these problems, a PLFS has been developed by utilizing surface-enhanced Raman scattering (SERS) for sensing signal transduction. In particular, a hierarchical three-dimensional nanostructure has been designed to create "hot spots", which can significantly amplify the SERS sensing signal, leading to high sensitivity. As a result, this PLFS has demonstrated a limit of detection (LOD) of 5.0 pg mL−1 toward detection of S-100β, a traumatic brain injury (TBI) protein biomarker in blood plasma. The PLFS has been successfully used for rapid measurement of S-100β in clinical TBI patient samples taken in the emergency department. Availability of PLFS for blood testing would shift the paradigm of TBI patient management and clinical outcome in emergency departments. It is expected that this type of PLFS can be adapted for rapid detection of various human diseases due to its capability of measuring a low level of protein blood biomarkers in complex human fluids. • A paper biosensor for the detection of protein biomarker in blood plasma is proposed. • A hierarchical 3D plasmonic nanostructure is developed to improve detection sensitivity. • A two-order of magnitude improvement in detection sensitivity is obtained. • Test results from the proposed sensor are comparable to those by the standard ELISA in clinical samples. • The proposed sensor provides guidance for rational design of highly sensitive and anti-interference POC devices. [ABSTRACT FROM AUTHOR]

Drug detection in biofluids has always been great importance for clinical diagnosis. Many detection technologies such as chromatography-mass spectrometry, have been applied to the detection of drugs. However, these technologies required multi-step operations, including complicated and time-consuming pretreatment processes and operations of bulky detection instruments, significantly limiting development of drug detection in clinical diagnosis. Herein, a portable 3D-printed paper cartridge was fabricated for fast sample preconcentration and direct drugs quantitative detection in biofluids by a portable Raman spectrometer. This cartridge contained both paper tip with silver nanowires to preconcentrate samples and achieve surface-enhanced Raman Scattering (SERS) measurement, and 3D-printed cartridge to build enclosed environment for the improvement of detection, which cost only one dollar. The preconcentration ability of the cartridge was up to 18.13-fold fluorescence enhancement and compared to the non-preconcentration method, it achieved 9.93-fold improvement of SERS performance. The anticancer drug of epirubicin hydrochloride, cyclophosphamide and their mixtures were quantitatively detected in the bovine serum or artificial urine. The integrated detection procedure required only 1 h, including sample pretreatment and preconcentration, drying, SERS measurements, and quantification analysis. This 3D-printed paper cartridge constituted a portable detection platform that would be potentially a practical and point-of-care detection tool for drug preconcentration and quantification on the clinical diagnosis. [Display omitted] • 3D-printed paper cartridge was fabricated for fast sample preconcentration and direct drugs quantitative detection in biofluids by a portable Raman spectrometer. • The preconcentration ability of the cartridge was up to 18.13-fold fluorescence and 9.93-fold enhancement of SERS. • The anticancer drug of epirubicin hydrochloride, cyclophosphamide and their mixtures were quantitatively detected in the bovine serum or artificial urine. • The integrated detection procedure of 3D-printed paper cartridge required only 1 hour, including sample pretreatment and preconcentration, drying, SERS measurements, and quantification analysis. [ABSTRACT FROM AUTHOR]

A simple spray method is utilized to prepare plasmonic paper loaded with gold nanoparticles (AuNPs) to serve as a signal enhancing substrate for surface enhanced Raman scattering (SERS) spectroscopy. The spray coating of plasmonic AuNPs onto hydrophilic porous paper-based materials notably improves their loading efficiency and distribution profile in much shorter time compare to typical dip- or drop-coating methods. This preparation approach involves the rapid drying of the solution to prevent the loss of the nanoparticles on the hydrophilic paper, which results in the improved packing of the plasmonic nanoparticles with local aggregations. Upon treating these spray-coated substrates with Raman reporter molecules, their sensing capability of SERS is a minimum of 2 times higher than that found with a dip-coated platform. Subsequently applying an additional layer of AuNPs onto these two substrates by dip- and spray-coating methods readily leads to greatly enhanced SERS signals over 2–5 times that are mainly caused by the plasmonic couplings and hot spots of sandwich-type structures. Without the modification of the paper substrates, the way the sandwich structure is formed on the paper materials with typical AuNPs significantly influences the packing and structural properties of the plasmonic nanoparticles, thereby highly impacting the SERS enhancement patterns. Image 1 • Plasmonic nanoparticles are rapidly loaded onto porous filter paper to serve as SERS substrates. • Spray coating readily controlled the packing and structural properties of plasmonic nanoparticles. • Applying an additional layer of nanoparticles onto plasmonic paper further improves their SERS response. [ABSTRACT FROM AUTHOR]

This study aims to develop a simple, sensitive, low-cost, environmentally friendly and flexible surface-enhanced Raman scattering (SERS) platform, combined with a portable Raman spectrometer, for the rapid and on-site SERS detection of bacteria. Commercial tobacco packaging paper (TPP) with little background interference was used as a loading medium that effectively adsorbed Au nanoparticles and provided sufficient "hot spots". This Au-tobacco packaging paper (Au-TPP) substrate used as a flexible SERS platform can maximize sample collection by wiping irregular surfaces, and was successfully applied to the on-site and rapid detection of pathogenic bacteria. Raman fingerprints of pathogenic bacteria can be obtained by SERS detection of spiked pork using wipeable Au-TPP, which verifies its value in practical applications. The results collected by SERS were further verified by polymerase chain reaction (PCR) results. It showed several advantages in on-site SERS detection, including accurate discrimination, simple preparation, easy operation, good sensitivity, accuracy and reproducibility. This study indicates that the established flexible SERS platform has good practical applications in pathogenic bacterial identification and other rapid detections. [ABSTRACT FROM AUTHOR]

[Display omitted] • Distinctive hydrophilic-hydrophobic SERS substrates have been fabricated utilizing ordinary papers loaded with Ag nanowires. • Remarkable SERS activity with an enhancement factor (EF) up to 2.63 × 106 was achieved. • An in-situ detection of trace furazolidone on fish under the interference of malachite green was realized. As a typical membrane matrix with attractive flexibility, paper has exhibited great feasibility to serve as surface-enhanced Raman scattering (SERS) substrate in the environmental monitoring and surveillance. In this research, we have designed and fabricated a distinctive hydrophilic-hydrophobic SERS substrate utilizing several ordinary papers loaded with Ag nanowires (Ag NWs). Remarkable SERS activities with an enhancement factor (EF) up to 2.63 × 106 was successfully achieved in the assembly Ag NWs with the optimal amount of nanotips and overlaps. The hydrophilic-hydrophobic strategy could contribute to anchoring microdroplets and thus enrich analytes to improve the homogeneity of substrate with a low relative standard deviation of 10.6%. Furthermore, the sophisticated SERS substrate was also applied in the in-situ detection of trace furazolidone on fish under the interference of malachite green and the reliable recovery rates were demonstrated as well. [ABSTRACT FROM AUTHOR]

The document from Lab on a Chip, published by The Royal Society of Chemistry, features various papers on micro- and nanoscale devices and applications. Topics covered include a self-actuated microfluidic chiplet for nucleic acid amplification, utilization of microdroplets for surface-enhanced Raman spectroscopy, nanofluidic energy harvesting, real-time myocardial infarction diagnosis, and more. The journal showcases cutting-edge research in the field of microfluidics and nanotechnology, providing valuable insights for researchers and scientists in the chemistry community. [Extracted from the article]

[Display omitted] • A SERS active sensor to measure microdroplets pH was designed. • The effects of acid species and ionic strength were investigated. • The pH detection of size-resolved micron-scale single droplet was realized. • Our method's applicability to ambient samples was showcased. Microdroplets present unique physiochemical properties, which can influence chemical reactions and atmospheric aerosol processes. The microdroplets' pH is one of the most important factors that dictate chemical processes, such as heterogeneous and condensed reactions. However, currently, there is no well-established method for directly measuring the pH in microdroplets. Herein, we develop a straightforward method, for the first time, to directly measure the pH of size-resolved, micron-sized single droplets with Surface Enhanced Raman Scattering (SERS)-activated pH-indicator paper; realized by embedded Au nanoparticles (20, 40 and 60 nm). We establish the key parameters for optimizing the method, and demonstrate its accuracy by benchmarking various acids and solutions with different ionic strength. With the established method, we report the pH dependence on the size of microdroplets. Microdroplets of sizes down to 230 nm can be analyzed by our method. We also showcase our method's applicability to ambient samples, establishing its promising potential beyond the laboratory environment. [ABSTRACT FROM AUTHOR]

Surface-enhanced Raman spectroscopy (SERS) technology is an attractive method for the prompt and accurate on-site screening of illicit drugs. As portable Raman systems are available for on-site screening, the readiness of SERS technology for sensing applications is predominantly dependent on the accuracy, stability and cost-effectiveness of the SERS strip. An atmospheric-pressure plasma-assisted chemical deposition process that can deposit an even distribution of nanogold particles in a one-step process has been developed. The process was used to print a nanogold film on a paper-based substrate using a HAuCl4 solution precursor. X-ray photoelectron spectroscopy (XPS) analysis demonstrates that the gold has been fully reduced and that subsequent plasma post-treatment decreases the carbon content of the film. Results for cocaine detection using this substrate were compared with two commercial SERS substrates, one based on nanogold on paper and the currently available best commercial SERS substrate based on an Ag pillar structure. A larger number of bands associated with cocaine was detected using the plasma-printed substrate than the commercial substrates across a range of cocaine concentrations from 1 to 5000 ng/mL. A detection limit as low as 1 ng/mL cocaine with high spatial uniformity was demonstrated with the plasma-printed substrate. It is shown that the plasma-printed substrate can be produced at a much lower cost than the price of the commercial substrate. [ABSTRACT FROM AUTHOR]

Putrescine and cadaverine are important volatile indicators for the evaluation of food spoilage. In this study, a metal-organic framework (MOF)-coated surface-enhanced Raman scattering (SERS) paper platform for the detection of putrescine and cadaverine is developed. Au@ zeolite imidazolate framework-8 (ZIF-8) SERS paper is fabricated by the coating of ZIF-8 layer on a Au nanoparticle-impregnated paper that is prepared by dry plasma reduction. The Au@ZIF-8 SERS paper is characterized by scanning electron microscope, energy-dispersive X-ray spectroscopy, X-ray diffraction, and N 2 sorption isotherm. The ZIF-8 layer enables the accumulation of gaseous molecules and also provides enhancement of SERS signals. The fluorescence, SERS, and simulation results prove the improved detection ability of the Au@ZIF-8 platform for the volatile molecules. For the selective detection of putrescine and cadaverine, the Au@ZIF-8 SERS paper is functionalized with 4-mercatobenzaldehyde (4-MBA). The 4-MBA molecule acts as a Raman reporter and also a specific receptor for the volatile amine molecules. Using the intensity ratiometric detection of 4-MBA-functionalized Au@ZIF-8 SERS paper, putrescine and cadaverine are quantitatively detected with detection limits of 76.99 and 115.88 parts per billion, respectively. Furthermore, the detection of volatile amine molecules released from spoiled salmon, chicken, beef, and pork samples is demonstrated. It is anticipated that the MOF-coated SERS paper platforms will be applicable not only in food safety but other applications including disease diagnosis and environmental monitoring. • MOF-coated SERS-active platform enables the detection of volatile amines from foodstuffs. • Putrescine and cadaverine are detected with high sensitivity and selectivity using Au@ZIF-8 SERS paper. • Au@ZIF-8 SERS paper is applied to the determination of food freshness for the first time. [ABSTRACT FROM AUTHOR]

The document discusses the rapid development and increasing attention surrounding the use of nanomaterials, such as nanoparticles, in various practical contexts. It highlights research on the structure, properties, and applications of nanoparticles and nanomaterials, including innovative approaches like using fish scale carbon nanoparticles and plant extracts for synthesis. The document also presents studies on enhancing the properties of nanoparticles for applications in cancer treatment, enantioselective recognition, and environmental remediation, showcasing the diverse potential of nanomaterials in addressing complex challenges. [Extracted from the article]

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• PS-AuND@NF was demonstrated for pretreatment-free SERS measurement of raw bile juice. • The scheme was to quickly discriminate the gall bladder (GB) stone and GB polyp. • Initially, AuND with a high SERS efficiency was constructed on the porous frame of the NF. • The PS-AuND@NF was then built by positioning AuND@NF on a paper strip. • The discrimination accuracy improved to 88.9% by combining with 2T2D correlation analysis. For pretreatment-free SERS measurement of raw bile juice for the identification of gall bladder (GB) disease, a paper strip bridging Au nanodendrite-encaged nickel foam (PS-AuND@NF) was demonstrated. To build a medium for facile sample diffusion as well as SERS generation, Au nanodendrite (AuND) with a high SERS efficiency was constructed on the porous frame of the NF (AuND@NF). Then, the PS-AuND@NF was built by simply positioning AuND@NF on a paper strip, which functioned as a channel for sample introduction to AuND@NF and a subsequent sample drain. With the continuous elution of raw bile juice, non-specific adsorption of SERS-inactive constituents such as lipids on the Au surface could be minimized. Using the PS-AuND@NF, raw bile juice samples obtained from 6 GB polyp and 21 GB stone patients were measured. Since only a few components in bile juice are expected to be SERS-active such as bilirubin-containing metabolites, the information obtained from the SERS spectra is not descriptive enough for the discrimination of both GB diseases. Therefore, two-trace two-dimensional (2T2D) correlation analysis, which is able to effectively feature out asynchronous (dissimilar) spectral behaviors in the comparison of two spectra, was carried out in parallel. When the principal component (PC) scores obtained from the 2T2D slice spectra were used for the k -nearest neighbor (k -NN), the discrimination accuracy improved to 88.9 % from 81.5 % obtained when using the PC scores of the raw spectra. Overall, the PS-AuND@NF enabled simple pretreatment-free SERS analysis of complex and viscous bile juice without interference from other existing components. [ABSTRACT FROM AUTHOR]

• We devise a PCR-coupled paper-based SERS sensor for rapid and sensitive bacterial DNA detection. • A facile and low-cost paper-based SERS substrate composed of AgNWs was prepared via vacuum filtration. • The minimum gene amplification and concentration conditions were optimized compared to RT-PCR method. • An array-type rapid kit prototype was prepared and tested for bacterial DNA detection within 30 min. A paper-based surface-enhanced Raman scattering (SERS) substrate composed of silver-nanowires (AgNWs) was coupled with polymerase chain reaction (PCR) for rapid and sensitive determination of respiratory bacterial DNA. EvaGreen dye, which is a DNA intercalating molecule, was introduced to the low-cycled PCR product, and the difference in dye intercalation in the DNA structure was quantified by Raman spectroscopy to verify the presence of a target gene. Mycoplasma pneumoniae (M. Pne), was selected as a target for the sensing demonstration. At various gene concentrations and amplification cycles, detection capability of fluorescence-based real-time PCR (RT-PCR) and the PCR-coupled SERS method were compared to develop a DNA detection system capable of low-cycle amplification and sensitive DNA sensing. After 10 cycles, the PCR-coupled SERS method showed enhanced detection capability with a DNA detection limit of 3.12 pg/μL. Then, the SERS substrate was prepared as a rapid kit that included a test line and negative and positive control lines. Target DNA after 10 cycles of amplification was successfully discriminated compared to non-target DNA and it was statistically relevant. The developed system is expected to be used as a detection method for various bacteria and viruses, and also be integrated with diverse POC diagnostic systems. [ABSTRACT FROM AUTHOR]

Significance: Cardiac troponin I (cTnI) is a primary biomarker for diagnosis of myocardial infarction (MI). In contrast to central laboratory tests for cTnI, point-of-care (POC) testing has the advantage of providing results when the patient is first encountered, which helps high-risk patients to be treated more rapidly and low-risk patients to be released in a timely fashion. A paper fluidic platform is good for POC testing because the paper is abundant, low cost, and disposable. However, current cTnI assays on paper platforms use antibodies as the recognition element, which has limitations due to the high cost of production and antibody stability issues at the POC. Aim: To develop an aptamer-based assay on a paper strip using surface-enhanced resonance Raman spectroscopy (SERRS) for detection of cTnI in the clinically relevant range at the POC. Approach: Gold nanoparticles (AuNPs) were functionalized with a Raman reporter molecule, malachite green isothiocyanate. The functionalized AuNPs were encapsulated in a silica shell and provided a SERRS signal using a handheld Raman system with a 638-nm excitation wavelength. A primary aptamer and a secondary aptamer of cTnI were used in a sandwich assay format to bind the cTnI on a test line of a paper fluidic platform. By measuring the SERRS signal from the test line, the concentration of cTnI was quantitatively determined. Results: The aptamer-based SERRS assay on a paper strip had a detection range of 0.016 to 0.1 ng / ml for cTnI, had good selectivity for cTnI compared to three other markers, had good stability over 10 days, and had good performance in the more complex serum sample matrix. Conclusions: The aptamer-based SERRS assay on a paper strip has the potential to provide a sensitive, selective, stable, repeatable, and cost-effective platform for the detection of cTnI toward eventual use in diagnosis of MI at the POC. [ABSTRACT FROM AUTHOR]

• AgNP-BNC paper was fabricated as an eco-friendly disposable, flexible SERS substrate. • The prepared AgNP-BNCPs have high SERS activity, good reproducibility and stability. • BNC exhibits potential as an alternative substrate to plastics for SERS applications. • SERS active AgNP-BNC paper achieves paste-and-read detection of pesticides on fruits. This study aimed to develop an eco-friendly flexible surface-enhanced Raman scattering (SERS) substrate for in-situ detection of pesticides using biodegradable bacterial nanocellulose (BNC). Plasmonic silver nanoparticle- bacterial nanocellulose paper (AgNP-BNCP) composites were prepared by vacuum-assisted filtration. After loading AgNPs into BNC hydrogel, AgNPs were trapped firmly in the network of nanofibrous BNCP upon ambient drying process, resulting in 3D SERS hotspots within a few-micron depth on the substrate. The fabricated AgNP-BNCPs exhibited high SERS activity with good reproducibility and stability as demonstrated by the detection of 4-aminothiophenol and methomyl pesticide. Due to the optical transparency of BNCP, a direct and rapid detection of methomyl on fruit peels using AgNP-BNCPs can be achieved, demonstrating a simple and effective 'paste-and-read' SERS approach. These results demonstrate potential of AgNP-BNCP composites for user-friendly in-situ SERS analysis. [ABSTRACT FROM AUTHOR]

The use of SERS for real-world bioanalytical applications represents a concrete opportunity, which, however, is being largely delayed by the inadequacy of existing substrates used to collect SERS spectra. In particular, the main bottleneck is their poor usability, as in the case of unsupported noble metal colloidal nanoparticles or because of the need for complex or highly specialized fabrication procedures, especially in view of a large-scale commercial diffusion. In this work, we introduce a graphene paper-supported plasmonic substrate for biodetection as obtained by a simple and rapid aerosol deposition patterning of silver nanowires. This substrate is compatible with the analysis of small (2 μL) analyte drops, providing stable SERS signals at sub-millimolar concentration and a detection limit down to the nanogram level in the case of hemoglobin. The presence of a graphene underlayer assures an even surface distribution of SERS hotspots with improved stability of the SERS signal, the collection of well-resolved and intense SERS spectra, and an ultra-flat and photostable SERS background in comparison with other popular disposable supports. [ABSTRACT FROM AUTHOR]

The document titled "Analyst" published by The Royal Society of Chemistry in 2025 showcases a variety of research articles in the field of chemistry. Topics covered include the development of electrochemical sensors, portable gas chromatograph-mass spectrometer, fluorescent biosensors, and more. The journal aims to connect the global community with advancements in the chemical sciences while reinvesting profits back into the chemistry community. [Extracted from the article]

Surface-enhanced Raman spectroscopy (SERS) holds remarkable potential for the rapid and portable detection of trace molecules. However, the analysis and comparison of SERS spectra are challenging due to the diverse range of instruments used for data acquisition. In this paper, a spectra instrument transformation framework based on the penalized functional regression model (SpectraFRM) is introduced for cross-instrument mapping with subsequent machine learning classification to compare transformed spectra with standard spectra. In particular, the nonparametric forms of the functional response, predictors, and coefficients employed in SepctraFRM allow for efficient modeling of the nonlinear relationship between target spectra and standard spectra. In the leave-one-out training and test of 20 analytes across four instruments, the results demonstrate that SpectraFRM can provide interpretable corrections to peaks and baseline spectra, leading to approximately 11% error reduction, compared with original spectra. With an additional feature extraction step, the transformed spectra outperform the original spectra by 10% in analytes identification tasks. Overall, the proposed method is shown to be flexible, robust, accurate, and interpretable despite varieties of analytes and instruments, making it a potentially powerful tool for the standardization of SERS spectra from various instruments. [ABSTRACT FROM AUTHOR]

Paper-based analytical devices (PADs) have emerged as a promising approach to point-of-care (POC) detection applications in biomedical and clinical diagnosis owing to their advantages, including cost-effectiveness, ease of use, and rapid responses as well as for being equipment-free, disposable, and user-friendly. However, the overall sensitivity of PADs still remains weak, posing a challenge for biosensing scientists exploiting them in clinical applications. This review comprehensively summarizes the current applicable potential of PADs, focusing on total signal-amplification strategies that have been applied widely in PADs involving colorimetry, luminescence, surface-enhanced Raman scattering, photoacoustic, photothermal, and photoelectrochemical methods as well as nucleic acid-mediated PAD modifications. The advances in signal-amplification strategies in terms of signal-enhancing principles, sensitivity, and time reactions are discussed in detail to provide an overview of these approaches to using PADs in biosensing applications. Furthermore, a comparison of these methods summarizes the potential for scientists to develop superior PADs. This review serves as a useful inside look at the current progress and prospective directions in using PADs for clinical diagnostics and provides a better source of reference for further investigations, as well as innovations, in the POC diagnostics field. [ABSTRACT FROM AUTHOR]