On-site Screening Research Articles

The development of rapid immunoassays for the urinary analysis of 1-hydroxypyrene glucuronide facilitate both laboratory and on-site polycyclic aromatic hydrocarbon biomonitoring

Polycylic Aromatic Hydrocarbons (PAHs) are produced during the incomplete burning of organic materials. PAH sources include vehicle exhaust, tobacco smoke and waste incineration. Environmental and occupational exposures to PAHs are known to occur. Cancer is a significant endpoint of PAH exposure and several occupations associated with high PAH exposure have been classified by IARC as carcinogenic to humans (Group 1).Pyrene is a common component of PAH mixtures and metabolism of pyrene leads to the excretion of 1-hydroxypyrene glucuronide (1-OHPyrG) in urine. Laboratory measurement of urinary 1-OHPyrG is employed in occupational and environmental biomonitoring programmes. The production of an anti-1-OHPyrG monoclonal antibody would allow the development of a PAH biomonitoring ELISA facilitating large scale laboratory screening and routine testing.The development of a lateral flow immunoassay and the production of a field test (point of use test) would greatly increase the value of biomonitoring. A novel Lateral Flow has been developed which employs an anti-1-OHPyrG sheep monoclonal antibody (Mab) to capture the PAH metabolite. The captured metabolite is visualised through a second Mab raised against the Mab-1-OHPyrG immune complex. This sandwich assay provides a positive correlation between the assay signal and biomarker concentration.A Smartphone camera allows signal measurement and a carefully considered ‘app’ provides result interpretation and data analysis. Results are provided in an exposed/not-exposed format. Performance of the lateral flow was confirmed through a comparative study and field trial. The development of a lateral flow test provides "real-time" analysis to occupational health professionals. On-site screening allows the immediate confirmation of safe working practice, provides immediate reassurance to those involved in potentially hazardous activities and greatly increases the efficacy of biomonitoring.

Three birds with one stone: A nano zeolitic imidazolate framework-luciferase-antimicrobial peptide biocomposite-based biosensing platform for improving enzyme stability, detection sensitivity, and sterilization effect

Adenosine triphosphate-driven bioluminescence (ATP-BL) biosensors were widely employed for on-site screening of bacteria. However, unstable luciferase with strict storage conditions limited its field detection. Moreover, the traditional ATP-BL biosensors lacked the sterilization effect. In this study, a robust and multifunctional zeolitic imidazolate framework-90 decorated with luciferase and polyethylene glycol–antimicrobial peptides (ZIF-90@Luc-AMP) was prepared. It could not only enhance the activity and stability of luciferase at ambient temperatures (≥1 month) but also sensitively detect target bacteria via the bioluminescence (BL) method and kill them (three birds with one stone). During the detection process, the target pathogen Escherichia coli O157:H7 (E. coli O157:H7) was specifically captured on a phage-modified stir bar and formed a sandwich complex with ZIF-90@Luc-AMP. With the synergistic bacteriolysis of ZIF-90@Luc-AMP and the phage, the captured E. coli O157:H7 was decomposed and emitted adenosine triphosphate (ATP), achieving the sterilization effect. Meanwhile, the introduced luciferase catalyzed ATP to produce a BL signal, which was proportional to the concentration of E. coli O157:H7. Combining ZIF-90@Luc-AMP and a phage-labeled stir bar for target recognition and enrichment, the entire analytical process could be easily manipulated within 30 min with a low limit of detection (20 CFU/mL) through a portable ATP bioluminescent meter. The multifunctional ZIF-90@Luc-AMP biosensor with high stability, specificity, and sensitivity was also appropriate for rapid pathogen screening and antibacterial application in the wild.

Microfluidic paper-based colorimetric chemo-sensing of formaldehyde using tetramethylbenzidine-conjugated gold nanoflowers: A point-on-demand approach for efficient chemosensing of volatile organic compounds

The presence of formaldehyde, a common environmental aldehyde and a recognized carcinogen, poses a significant health risk to humans. Monitoring its levels in environmental samples and human biofluids is crucial for both pollution control and advancements in health science. This study introduces an effective colorimetric method utilizing UV–Vis spectroscopy to identify formaldehyde in real samples. Various types of gold nanoparticles (AuNPs) with diverse sizes and structures were employed to develop a photochemical chemosensing device. The method exhibited high sensitivity in detecting formaldehyde, particularly through the use of gold nanoflowers (AuNFs) at a pH of 6.15, with a low quantification limit of 0.1 µM and a linear range of 0.6 µM to 1 M. Furthermore, the method was successfully utilized to assess formaldehyde in human biofluids. Additionally, a paper-based microfluidic colorimetric opto-device was incorporated for on-site and on-demand formaldehyde screening. This study showcases the application of AuNPs for the precise and sensitive detection of formaldehyde in human biofluids, offering potential for advanced analytical methods targeted at formaldehyde and other volatile organic compounds (VOCs). The practicality, affordability, and portability of the microfluidic paper-based colorimetric device (µPCDs) make it a promising choice for point-of-care VOC testing. This represents the first demonstration of µPCDs for the selective photochemical sensing of toxic substances, and its one-step process that does not rely on novel sorbents, membranes, or external stimuli, making it easily scalable. The potential for µPCDs to be broadly applicable to the selective monitoring of formaldehyde from complex bio-matrices is evident. This method demonstrated robust performance in terms of accuracy, sensitivity, reproducibility, and selectivity.

Marangoni flow-guided molecular accumulation for sensitive and rapid SERS detection of phthalates

Public attention has been emerging for the prevention and assessment of healthcare risks from phthalate esters (PAEs) in daily life. For the effective detection of small environmentally hazardous materials, we suggest two major points: i) the formation of high-density hotspots and ii) the delivery of molecules to the activated plasmonic regions. In this study, we developed a method for laser-induced Marangoni flow in cotton fabric (CF) nanopillars (NPs) deposited with Au (Au/CFNPs) for the detection of PAEs by surface-enhanced Raman spectroscopy (SERS). We optimized the performance of the Au/CFNP platforms by adjusting both the maskless plasma etching time and the Au deposition thickness. Narrow (∼8 nm) and populated hotspots were achieved at an Ar plasma treatment time of 30 s and a Au thickness of 150 nm. The molecular behaviors were observed via real-time monitoring of SERS signals. Under continuous laser illumination, Marangoni radial convection flow became predominant over the outward capillary force, resulting in molecular accumulation in the detection areas. For small probe dyes and PAEs, the maximum intensities were achieved within 80 s after the injection of analytes and their signal fluctuations were estimated to have a relative standard deviation of < 10 %, which indicated sensitive and reproducible sensing. The prediction of PAEs extracted from the actual samples was investigated on the basis of a model used to quantitatively fit reference samples and the results were compared with those obtained by high-performance liquid chromatography. The results demonstrated that the combination of densified hotspots on three-dimensional porous substrates and laser-induced Marangoni flow is highly desirable for on-site early screening assays for low-quantity harmful materials present in surrounding environments.

Portable detection of Salmonella in food of animal origin via Cas12a-RAA combined with an LFS/PGM dual-signaling readout biosensor.

Ahighly specific and sensitive rapid two-signal assay was developedfor the detection of Salmonella typhimurium in foods of animal origin. TheinvA gene of Salmonella was usedas the biorecognition element and recombinase-assisted amplification (RAA) technology for signal amplification. By utilizing the specific recognition and efficient trans-cleavage activity of CRISPR/Cas12a, point-of-care testing (POCT) for S. typhimurium was achieved via lateral flow strips (LFS) and personal glucometer (PGM) biosensors as dual signal readout systems, with sensitivities of 33CFU/mL and 20CFU/mL, respectively. Users can select the appropriate test system on the basis of specific application requirements: LFSs are ideal for rapid onsite screening, whereas glucometer biosensors offer precise quantitative determination. This approach simplifies the use of large instruments and overcomes site constraints, demonstrating good accuracy and applicability in animal-derived samples, with significant potential for the detection of other pathogens and for use in restricted environments.

Integrated Sensing Platform Validated for the Efficient and On-Site Screening of Amine-Containing Illicit Drugs.

Efficient and reliable technologies for the on-site detection of illicit drugs are important in drug-facilitated crime investigations. However, the development of such technologies is challenging. Based on the synthetic optimization, introducing a boron ester functional group to the two furanic indicators endows the stimulus-responsive properties synergistically. The ring-opening reaction of the indicators in the presence of amine-containing illicit drugs generated well-known donor-acceptor Stenhouse adducts, accompanied by strong color changes. A small-size and lightweight laminated sensor was integrated based on the outstanding ratiometric variations of the two active furanic indicators. A prototype platform was fabricated equipped with a circuit control, a mini pump, and a signal processing system. A user-friendly detection and efficient screening of amine-containing illicit drugs, including phenethylamines, amphetamines, cathinones, and tryptamines in the liquid states were conducted. The ratiometric response of the sensor was linear in the concentration range of 2.1-10.6 μg·mL-1 for methamphetamine·HCl and methcathinone ·HCl. The detection limits for the two illicit drugs at the sublevel (ng·mL-1) were found to be 8.4 and 9.0 ng·mL-1, respectively. Double-blind field tests and different illicit drugs were evaluated with good screening capability. Successful trials showed the potential applications of the developed prototype platform for efficient and on-site analytical determination.

Universal All-In-One Lateral Flow Immunoassay with Triple Signal Amplification for Ultrasensitive and Simple Self-Testing of Treponema pallidum Antibodies.

Lateral flow immunoassay (LFIA) is valued for its simplicity and rapidity for on-site screening, however, it experienced false negatives in real sample analysis due to low sensitivity. Although many signal amplification techniques can improve the sensitivity, they usually require additional complicated steps. To address these issues, taking Treponema pallidum (T. pallidum) antibodies as a model detecting target, herein, we report an all-in-one LFIA (AIO-LFIA) with triple-step signal amplification to significantly improve sensitivity while maintaining simplicity. This LFIA utilizes a biotin-streptavidin system for initial signal amplification, followed by introducing a release controller with a specific imprinted structure for timed multicomponent release, which avoids the extra steps when adding components in traditional LFIA. Particularly, a 3D-printed programmed metal in situ growth (MISG) device is integrated to localize signal enhancement at specific sites, overcoming limitations of traditional MISG and substantially reducing reagent usage and assay time, and the nitrocellulose membrane surface was much cleaner than the conventional approach, which facilitates signal readout. After optimization, the proposed AIO-LFIA is capable of visual detection down to 1 pg/mLT. pallidum antibodies in 15 min, 1000-fold lower than the gold nanoparticle-based LFIA. In clinical testing of 152 samples, the AIO-LFIA can distinguish all positive samples, outperforming commercial LFIA which missed those positive samples with relatively low antibody levels. Thus, this study presents a universal ultrasensitive and reliable AIO-LFIA strategy for infectious diseases self-testing, providing an effective promising prospect to address the challenge over emerging infectious diseases in the future.

Low-cost signal enhanced colorimetric and SERS dual-mode paper sensor for rapid and ultrasensitive screening of mercury ions in tea

Mercury ions (Hg2+) are highly toxic heavy metals that are commonly found in natural environments. Owning to their non-biodegradability and accumulation in the food chain, the precise detection of trace amounts of Hg2+ is essential for preventing chronic accumulation and ensuring food safety. In this study, we present a dual-mode paper sensor for simultaneous colorimetric and Surface-Enhanced Raman Spectroscopy (SERS) detection of Hg2+ in tea, achieving ultrasensitive, rapid, and on-site screening. 4-Mercaptopyridine (4-MPY) was effectively chemisorbed onto the gold nanoparticles (AuNPs), acting as a signal probe for colorimetric methods. Moreover, it can produce plasmonic hot spots for SERS by interacting with the pyridine ring. To enhance the signal intensity of both colorimetry and SERS, a silver shell is in-situ grown on the surface of AuNPs captured on the paper sensor by reduction of Ag+, achieving signal amplification. The visual limit of detection (LOD) for the colorimetric biosensor is 2.5 pM, while the LOD of SERS is 0.48 pM with this dual-mode paper sensor. The sensitivity of both the colorimetric method and SERS was improved by approximately 200 and 500 times, respectively, with the designed signal amplification strategy. The system allows for multiple parallel screening of the same sample, ensuring accurate results without any false-positive or false-negative. This study provides a valuable platform for the accurate detection of various other heavy metal ions and provides effective strategies for improving the performance of colorimetric methods.

Breathomics: may it become an affordable, new tool for early diagnosis of non-small-cell lung cancer? An exploratory study on a cohort of 60 patients.

Analysis of breath, specifically the patterns of volatile organic compounds (VOCs), has shown the potential to distinguish between patients with lung cancer (LC) and healthy individuals (HC). However, the current technology relies on complex, expensive and low throughput analytical platforms, which provide an offline response, making it unsuitable for mass screening. A new portable device has been developed to enable fast and on-site LC diagnosis, and its reliability is being tested. Breath samples were collected from patients with histologically proven non-small-cell lung cancer (NSCLC) and healthy controls using Tedlar bags and a Nafion filter attached to a one-way mouthpiece. These samples were then analysed using an automated micro portable gas chromatography device that was developed in-house. The device consisted of a thermal desorption tube, thermal injector, separation column, photoionization detector, as well as other accessories such as pumps, valves and a helium cartridge. The resulting chromatograms were analysed using both chemometrics and machine learning techniques. Thirty NSCLC patients and 30 HC entered the study. After a training set (20 NSCLC and 20 HC) and a testing set (10 NSCLC and 10 HC), an overall specificity of 83.3%, a sensitivity of 86.7% and an accuracy of 85.0% to identify NSCLC patients were found based on 3 VOCs. These results are a significant step towards creating a low-cost, user-friendly and accessible tool for rapid on-site LC screening. ClinicalTrials.gov Identifier: NCT06034730.

A Smartphone Operated Intelligent Stochastic Miniplatform for On-Site Screening of Milk for Fast Determination of Ochratoxin A

Ochratoxine A is a very stable mycotoxin which cannot be destroyed below 250°C. Found in grains, coffee, grapes, wine, milk, and meat, it can produce kidney damage and cancer. Therefore, a smartphone operated intellingent stochastic miniplatform was designed, characterised, and validated for the on-site screening of milk for fast determination of ochratoxine A. (Z)-N-[2-(4-hydroxyphenyl) ethyl]octadec-9-enamide was used as modifier of a gold matrix for a screen printed stochastic sensor used as sensing tool in the design of the miniplatform. A wide linear concentration range (1.0 × 10−15 − 1.0 × 10−7 mol l‒1) and a low limit of quantification of 1 fmol l‒1 were achieved for the assay of ochratoxin A. Recovery values higher than 99.00% were obtained for ochratoxine A, when the miniplatform was used for the screening of cow’s milk and vegetarian milk.

Establishment of highly sensitive lateral flow immunochromatographic strips for quinclorac detection utilizing signal amplification nanoparticles

Highly selective herbicide quinclorac (Qui) is a type of quinoline carboxylic acid hormone herbicide, which has the characteristics of long half-life and difficulty for degradation, causing high risk to the environmental safety. In this study, anti-Qui 8A3 monoclonal antibody (mAb) with good specificity and high affinity (3.89 × 109 L/mol) was prepared, and two kinds of lateral flow immunochromatographic strips (LFICS) including nano-flower nanoparticles (AuNF) - and latex microsphere (LM)- based LFICS were established based on the antibody and signal amplification. The linear range of the AuNF- and LM- based LFICS were 5.31–345.48 ng/mL and 2.52–257.92 ng/mL, respectively. The limit of detection (LOD) of the AuNF- and LM- based LFICS were determined to be 5.31 ng/mL and 2.52 ng/mL, respectively. In summary, the developed LFICS using AuNF and LM as signal amplification reporters exhibited excellent sensitivity and provided the rapid on-site screening of Qui and other analytes in food safety field.

Fabrication of Raman reporter molecule–embedded magnetic SERS tag for ultrasensitive immunochromatographic monitoring of Cd ions and clenbuterol in complex samples

A rapid, simple but sensitive analytical method for the simultaneous monitoring of heavy metal ions and illegal additives in complex samples remains lacking. We reported a difunctional capture–detection surface-enhanced Raman scattering (SERS) immunochromatographic assay (ICA) for the direct detection of the heavy metal residue Cd ion (Cd2+) and illegal additive clenbuterol (CLE) with high sensitivity and specificity herein. A novel magnetic SERS tag (Fe@RAu) with a Raman reporter molecule–embedded raspberry-like Au shell was fabricated via a one-step reduction reaction that not only simplified the fabrication of common magnetic SERS nanomaterials but also improved SERS activity to increase detection sensitivity. The difunctional SERS–ICA enabled the fast magnetic enrichment of the target small molecules in complex specimens and ultrasensitive and quantitative determination of CLE/Cd2+ on the two test lines of the ICA system. The limits of detection of the developed method for CLE and Cd2+ were as low as 0.48 and 1.88 pg/mL, respectively, and about 2000 and 500 times lower than those of conventional AuNP-based ICA strips. The excellent practicability of Fe@RAu–ICA for real food samples analysis was also demonstrated, revealing the potential of the proposed assay for rapid and on-site screening of small-molecule pollutants.

In Situ Colorimetric LAMP Based on One-Step Modified Filter Paper to Screen Human Papillomavirus (HPV)16/18 from Clinical Samples.

Cervical cancer is among the most common malignant tumors in women. The development of rapid screening techniques plays an important role in early screening for cancer treatment. We have developed an HPV screening method, which effectively combines the high-efficiency nucleic acid enrichment of chitosan-modified filter paper and the rapid visual detectability of colorimetric LAMP, along with the enhancement of the tolerance ability of the pH-sensitive LAMP reagent to acidic original samples, making the detection of HPV 16/18 easy to carry out and reliable, which is helpful for the epidemiological prevention and control strategies of HPV-induced cancer. This technique can simultaneously exhibit the "in situ amplification" capability of chitosan-modified filter paper and the nontemperature cycle dependence of visual LAMP detection. Therefore, DNA extraction and amplification can be performed efficiently and quickly within a single reaction where all DNA is concentrated in the QF paper disc. By embedding amino-modified filter paper into the plastic chip, a simple and reliable disposable chip was prepared for rapid HPV16 and HPV18 detection from clinical endometrial samples, and the results were 100% consistent with clinical diagnosis. More importantly, even after the sample was diluted 100-fold, HPV16/18-infected cells could be accurately identified, showing the advantages of the system in early cancer screening. Moreover, for endometrial samples containing plenty of cells, the filter paper could be used to enrich cells by filtration, preventing the acidic fluid from impacting pH-induced colorimetric LAMP detection and realizing direct amplification for HPV identification without nucleic acid extraction. This easy-to-operate system that can analyze a wide range of samples will be suitable for routine on-site HPV screening, dramatically extending the applications and utility for rapid, near-patient nucleic acid testing.

Development and evaluation of rapid and simple detection of Klebsiella pneumoniae using closed dumbbell-mediated isothermal amplification diagnostic assay.

Klebsiella pneumoniae (K. pneumoniae) is the most common pathogen causing hospital respiratory tract infection and epidemic. Gold standard procedures of microscopic examination and biochemical identification are widely used in clinical diagnosis with disadvantages of low sensitivity, time-consuming and sophisticated equipment requiring. An efficient, nucleic acid amplification-based sensitive and specific on-site identification of K. pneumoniae in clinical is necessary to facilitate clinical medication and disease control. We developed a closed dumbbell mediated isothermal amplification (CDA) assay for the rapid and sensitive detection of conserved rcsA gene in K. pneumoniae by real-time fluorescence monitoring and end-point colorimetric judgement. We designed and selected a pair of inner primers of CDA to detect K. pneumoniae. Then outer and loop primers were designed and verified to accelerate CDA reaction to achieve more efficient detection of K. pneumoniae. The results showed the detection limit of CDA assay was 1.2 × 10-5 ng/μL (approximately 1 copy of the target gene) within 60 min, which was 100-fold more sensitive than real-time quantitative PCR (qPCR). Several pathogen genomic DNAs (Staphylococcus aureus, Shigella sonnei, Vibrio parahaemolyticus, Escherichia coli, Candida glabrata, Candida tropicalis, Candida parapsilosis, Candida albicans, Streptococcus agalactiae, Rickettsia, Listeria monocytogenes, Pseudomonas aeruginosa, Klebsiella oxytoca, and Klebsiella aerogenes) were used to evaluate the sensitivity and specificity of the established K. pneumoniae CDA assay. Total 224 batches of samples from other strains tested were negative and 296 batches of extracted K. pneumoniae DNA samples were positive by the developed CDA amplification approach, revealing high specificity and specificity of the diagnostic assay. In addition, the results of real-time fluorescence amplification of the K. pneumoniae CDA were in consistent with those of end-point colorimetric results. The established real-time fluorescence and visual CDA assays of K. pneumoniae with merits of rapid, sensitive and specificity could be helpful for on-site diagnosis and clinical screening in rural areas.

Programming of a Portable Digital Monitoring System-Integrated DNA Aptamer Reversely Regulated Oxidase-Like Nanozyme for Real-Time Dynamic Analysis of Atmospheric Perfluorooctanoic Acid.

Timely and efficient analysis of the fluorinated per- and polyfluoroalkyl substances (PFAS) in an atmospheric environment is critical to environmental pollution traceability, early warnings, and governance. Here, a portable, reliable, and intelligent digital monitoring device for onsite real-time dynamic analysis of atmospheric perfluorooctanoic acid (PFOA) is proposed. The sensing mechanism is attributed to the oxidase-like activity of PtCoNPs@g-C3N4 that is reversely regulated by the surface modification of a PFOA-recognizable DNA aptamer, engineering a PFOA-activated oxidase-like activity of nanozyme (Apt-PtCoNPs@g-C3N4) to combine the nonfluorescence o-phenylenediamine (OPD) as the dual-modality response system. The present PFOA interacts with its DNA aptamer and dissociates from the surface of Apt-PtCoNPs@g-C3N4, restoring the oxidase-like activity of PtCoNPs@g-C3N4 to oxidize OPD into yellow fluorescence 2,3-diphenylaniline (DAP), thereby observing a PFOA-triggered colorimetric as well as fluorescence dual-modality change. Then, a hydrogel kit-programmed Apt-PtCoNPs@g-C3N4 + OPD system is used as the sensitive element to incorporate into this homemade portable device, automatically gathering and processing the PFOA-triggered hydrogel colorimetric and fluorescence image gray values by our self-weaving software, ultimately realizing the onsite real-time dynamic analysis of atmospheric PFOA surrounding a fluorochemical production plant. This work provides a direction and theoretical foundation for designing portable onsite screening devices that cater to other atmospheric contaminants detection requirements.

Raman spectroscopy-based authentication of powder goat milk adulteration with cow milk

This study introduces, for the first time, the utilization of a handheld Raman spectrometer in conjunction with Data-Driven Soft Independent Modeling of Class Analogy (DD-SIMCA) for the authentication of powdered goat milk (target class) against adulteration with powdered cow milk. Since the representativeness of the target class is the first critical step to construct a model without overfitting or underfitting, especially when dealing with a few numbers of target samples, three distinct validation strategies (approaches 1, 2, and 3, respectively), incorporating no partitioning of the target samples, Procrustes cross-validation, and Kennard-Stone-based partitioning, were assessed. Moreover, the spectral data underwent preprocessing techniques including offset correction (OFF), multiplicative scatter correction (MSC), standard normal variate transformation (SNV), and Savitzky-Golay derivative (SGD). Achieving a correct classification rate of 100% for all studied samples using MSC for approaches 1 and 2, and SGD for approach 3, underscores the robustness of Raman spectroscopy in furnishing pertinent analytical insights for the authentication of pure powdered goat milk, with a significance level of 0.01. This methodology furnishes distinct spectral signatures associated with the macromolecular composition, particularly fats, proteins, carbohydrates, and carotenoids, facilitating the detection of adulterations as low as 1% w/w of cow milk added to powdered goat milk. Thus, the proposed method offers a rapid and reliable on-site screening tool, consonant with the principles of green food analysis, especially advantageous in situations where identifying the type and/or nature of the adulterants is not feasible.

A novel fluorescent nanoplatform for detecting acrolein and application to on-site evaluation of scavenging capacity

Acrolein is a high reactive and toxic aldehyde, commonly found in both dietary and environmental sources, and can also be produced endogenously. Given the highly toxicity of acrolein and its harmful effects on human health, many acrolein scavengers have been developed. However, a portable tool for on-site screening and evaluation of the capacity of acrolein scavengers is still rare. Herein, we have developed a fluorescence nanoplatform based on gold nanoclusters anchored to manganese dioxide (AuNCs-MnO2) nanocomposites co-utilizing with glutathione (GSH) for rapid and sensitive detection of acrolein. In AuNCs-MnO2 nanocomposites, MnO2 quenched the fluorescence of AuNCs. GSH can reduce MnO2 nanosheets to Mn2+, leading to the decomposition of MnO2 and release of AuNCs, accompanied by the fluorescence recovery. When acrolein was present, GSH reacted specifically with acrolein through Michael addition. Simultaneously, the formation of GSH-acrolein adduct hindered the reduction of MnO2 by GSH and the fluorescence recovery. The limit of detection (LOD) for acrolein was 0.082 μM. By constructing AuNCs-MnO2 hydrogels with a smartphone, a point-of-care detection of acrolein in food samples and ambient air was achieved, obtaining satisfactory results with a recovery of 97.27–108.71 % and RSD of 1.27–4.33 %. The developed portable smartphone-based hydrogels also demonstrated strong potential on the on-site evaluation of acrolein scavengers’ capacity. Furthermore, the nanoplatform was successfully applied to detect acrolein in living cells, providing a valuable reference for the diagnosis and treatment of acrolein-related diseases in clinical settings.

A simple and practical fluorescence method for on-site screening and accurate detection of 4-hexylresorcinol in crustacean aquatic products

4-hexylresorcinol (4-HR), a natural compound renowned for its innate antibacterial and antioxidant properties, finds pervasive utilization in preventing browning and extending the shelf life of products such as shrimp and crab. The manuscript presents a novel method for expeditious screening and precise quantification of 4-HR in crustacean aquatic products, based on the reaction between 4-HR and dopamine to yield a strongly fluorescent product. The innovative method has remarkable sensitivity, strong anti-interference capabilities, simplicity, and rapidity, thereby facilitating not only on-site screening in just 7.5 min but also meticulous in-laboratory detection with enhanced precision. The fluorescence intensity has a linear relationship with 4-HR content in the range of 0–100 μg/g, with a detection limit of 0.006 μg/g. The proposed method has the potential to become a standard for determining 4-HR in crustacean aquatic products, addressing limitations of existing techniques like high-performance liquid chromatography, which are complex and costly. This methodology holds great promise in ensuring the safety of crustacean aquatic products.

Detecting antimony(III) on-site using novel gel-based techniques: Colorimetric diffusive equilibrium in thin films for two-dimensional imaging and surface-enhanced Raman scattering for sensitive quantification

Antimony (Sb) pollution has raised increasing public concerns and its rapid on-site screening is central for the risk assessment. Herein, we proposed two gel-based methods based on colorimetric diffusive equilibrium in thin films (DET) and surface-enhanced Raman scattering (SERS), for two-dimensional imaging and sensitive detection of Sb(III) by revisiting the phenylfluorone (PhF) complexation reaction. PhF was well dispersed in the polyvinyl alcohol (PVA) hydrogel and reacted with Sb(III) in the DET gel to form a strong PhF-Sb(III) complex. The distribution of Sb(III) was easily visualized at a submillimeter resolution using computer imaging densitometry, with a detection limit (LOD) of ∼100 nmol L−1. Field application in the Sb mine area reveals limited dissolved Sb(III) penetrating the redox barrier below the sediment-water interface by 20 mm in rivers and tailing pond sediments. To improve the detection sensitivity and apply the principle to trace Sb quantification, a SERS platform was established by anchoring PhF on the hydrogel-stabilized Ag nanoparticles via C–O–Ag bonding to specifically detect Raman-inactive Sb(III). Benefiting from the high SERS activity of PhF and enrichment ability of hydrogel, Sb(III) was quantified with a LOD of 1.2–10.7 nmol L−1 depending on the sample volume. The coexisting ions at a 100-fold higher concentration than Sb(III) resulted in only 3.3–10.4 % variation in SERS intensity, indicating a negligible interference on the SERS platform. The platform exhibited a RSD of 6.6–13.1 % and acceptable recoveries for various environmental matrices, highlighting its promise in on-site application.

Molybdenum Disulfide-Assisted Spontaneous Formation of Multistacked Gold Nanoparticles for Deep Learning-Integrated Surface-Enhanced Raman Scattering.

Several fabrication methods have been developed for label-free detection in various fields. However, fabricating high-density and highly ordered nanoscale architectures by using soluble processes remains a challenge. Herein, we report a biosensing platform that integrates deep learning with surface-enhanced Raman scattering (SERS), featuring large-area, close-packed three-dimensional (3D) architectures of molybdenum disulfide (MoS2)-assisted gold nanoparticles (AuNPs) for the on-site screening of coronavirus disease (COVID-19) using human tears. Some AuNPs are spontaneously synthesized without a reducing agent because the electrons induced on the semiconductor surface reduce gold ions when the Fermi level of MoS2 and the gold electrolyte reach equilibrium. With the addition of polyvinylpyrrolidone, a two-dimensional large-area MoS2 layer assisted in the formation of close-packed 3D multistacked AuNP structures, resembling electroless plating. This platform, with a convolutional neural network-based deep learning model, achieved outstanding SERS performance at subterascale levels despite the microlevel irradiation power and millisecond-level acquisition time and accurately assessed susceptibility to COVID-19. These results suggest that our platform has the potential for rapid, low-damage, and high-throughput label-free detection of exceedingly low analyte concentrations.