SERS-active plasmonic metal NP-CsPbX(3) films for multiple veterinary drug residues detection

SERS based determination of ceftriaxone, ampicillin, and vancomycin in serum using WS2/Au@Ag nanocomposites and a 2D-CNN regression model

Accurate therapeutic drug monitoring (TDM) of antibiotics including ceftriaxone, ampicillin, and vancomycin plays an important role in the treatment of neonatal sepsis, a common and life-threatening disease in neonates. A highly sensitive surface-enhanced Raman spectroscopy (SERS) method using tungsten disulfide/gold and silver core-shell (WS2/Au@Ag) nanocomposites was developed for the rapid detection of the three antibiotics, with a wide response range (0.5-1000 μg/mL). A two-dimensional convolutional neural network (2D-CNN) regression model was proposed to predict antibiotic concentrations in complex mixed serum solutions, simulating various drug use scenarios. The model achieved excellent regression results for ceftriaxone and ampicillin simultaneously, with R-squared (R2) values of 0.9993 and 0.9997. The integration of ultra-sensitive SERS with the 2D-CNN based deep learning model provides a promising approach for rapid TDM and personalized patient treatment.

Multiplex immunochromatographic assay based on triple-color aggregation-induced emission fluorescent microspheres with good biocompatibility for the simultaneous detection of veterinary drugs in aquatic products

BACKGROUND

The simultaneous presence of multiple veterinary drug residues in a single sample poses a significant challenge for food safety analysis. Compared with traditional single-target detection, multiplex detection can not only provide richer sample information to raise the detection efficiency and reduce the possibility of false positives and omissions, but also decrease sample volume, shorten detection time, and lower costs. The luminance of aggregation-induced emission fluorescent microspheres (AIEFMs) can be enhanced by loading more fluorophores. The AIEFMs exhibit more advantages such as bright colors, excellent monodispersity, and high photostability, making them widely applicable in food safety.

RESULTS

We successfully developed a multiplex immunochromatographic assay (ICA) using triple-color AIEFMs as signal labels for the simultaneous detection of three veterinary drugs: chloramphenicol (CAP), diethylstilbestrol (DES), and diazepam (DZP). AIEFMs with good biocompatibility were synthesized via a simple and quick one-pot method based on the self-aggregation of AIEgens and the coating of metal-polyphenol network formed through the coordination of proanthocyanidin and Fe3+ in a tetrahydrofuran/water mixed solution. The as-prepared AIEFMs were rapidly conjugated with antibodies to synthesize AIEFM probes without any coupling reagent, and the multiplex AIEFMs-ICA was established for the detection of CAP, DES, and DZP. Under optimal conditions, the detection limits for CAP, DES, and DZP were 1.67, 410, and 5 pg/mL, respectively. The average recoveries of these veterinary drugs in fish and shrimp samples ranged from 85.40 % to 113.15 %, demonstrating the reliability and stability of the multiplex AIEFMs-ICA.

SIGNIFICANCE

The multiplex AIEFMs-ICA exhibited excellent signal output capacity, high specificity, and remarkable sensitivity. In brief, the developed multiplex AIEFMs-ICA shows great potential in the on-site detection of veterinary drugs and other targets.

A Surface-Enhanced Raman Spectroscopy Platform Integrating Dual Signal Enhancement and Machine Learning for Rapid Detection of Veterinary Drug Residues in Meat Products

The detection and quantification of veterinary drug residues in meat remain a significant challenge due to the complex background interference inherent to the meat matrix, which compromises the stability and accuracy of spectroscopic analysis. This study introduces an advanced label-free surface-enhanced Raman spectroscopy (SERS) platform for the precise identification and quantification of veterinary drugs. By employing a dual enhancement strategy involving sodium borohydride activation and calcium ion-deuterium oxide guidance, this platform achieves the efficient capture and signal amplification of drug molecules on highly active nanoparticles. High-quality SERS spectra were obtained for carprofen, doxycycline hydrochloride, chloramphenicol, and penicillin G sodium salt, enabling accurate classification and interference suppression. In addition, the application of machine learning algorithms, including PCA-LDA, heatmap, and decision tree modeling, allows for accurate differentiation of mixed drug samples. Quantitative analyses in meat samples were achieved through Raman intensity ratios and multivariate curve resolution-alternate least-squares (MCR-ALS) analysis, with results showing high consistency with high-performance liquid chromatography (HPLC) measurements. These findings highlight the potential of this SERS-based platform for accurate and rapid detection of multicomponent veterinary drug residues in complex food matrices.

Innovative quantum dots-based SERS for ultrasensitive reporting of contaminants in food: Fundamental concepts and practical implementations

Food contamination poses serious health risks, compelling the discovery of new methods to guarantee regulatory compliance and build consumer conviction. Surface Enhanced Raman Spectroscopy (SERS) has come into sight as a sophisticated approach for the ultrasensitive discovery of toxins in food and water, proposing non-destructive, quick, and precise analysis. Instantaneously, quantum dots (QDs) are astonishing nanomaterials, characterized by distinctive attributes such as quantum confinement and optical photostability. This article extends a decisive outline of SERS technology, pointing out its amalgamation with QDs and discussing numerous augmentation approaches i.e., chemical enhancement, electromagnetic enhancement, Van Hove singularities, the Brus equation, Förster resonance energy transfer, band gap energy, and quantum yield. The amalgamation of SERS with QDs commands an important promise in international food security and conservational sustainability. Nevertheless, QDs provide several compensations, they also aspect a few concerns, counting probable toxicity, stability problems, and predisposition to interference. To tackle these items, further research is required to synthesize safer, more stable QD materials and to refine protocols for practical real-world applications. While some reviews on SERS have been published recently, to our knowledge, the current review is the first one dedicated to QDs-assisted SERS in food safety.

High-Stability Printable Perovskite SERS Substrates in an Aqueous Environment via Plasmon-Induced Resonance Energy Transfer

The excellent photoelectric conversion efficiency and tunable bandgap of metal halide perovskites make them highly suitable for SERS applications. However, the low stability of perovskites in water and oxygen greatly hinders their use in SERS detection, particularly in biomolecule detection applications, which often require water-based test solutions. Herein, we report a gold (Au)/perovskite-polyvinylidene difluoride (PVDF) nanocomposite/ZnO nanoflower (GPPZ) SERS substrate capable of functioning in aqueous solutions. Its enhancement ability is attributed to plasmon-induced resonance energy transfer (PIRET) and an electromagnetic mechanism. The surface plasmon resonance created by ultrathin Au and ZnO nanoflowers induces resonance energy transfers to the perovskite via PIRET, facilitating a quasi-matched charge transfer between the perovskite and the probe molecule. The PVDF coating protects the perovskite from water and oxygen without affecting the resonance energy-transfer process. As a result, an enhancement factor (EF) approaching 1 × 106 was achieved for the crystal violet molecule. Additionally, we fabricated a flexible GPPZ substrate using silk screen printing, enabling mass production of an SERS array substrate. The printed flexible GPPZ substrates demonstrated micromole-level cysteine detection with an EF of 6.8 × 105, showing potential for application in hyperhomocysteinemia diagnosis.

Rational side-by-side self-assembly of gold nanorods with short and medium aspect ratios via the self-evaporation method to boost their potential as a surface-enhanced Raman scattering (SERS) substrate

Surface-enhanced Raman scattering (SERS) represents a compelling detection methodology centered on the electromagnetic fields, commonly termed "hot spots", generated around noble nanoparticles. Nonetheless, the efficacy of electromagnetic field (EMF) amplification is constrained when utilizing individual nanoparticles. There has been a notable lack of experimental and theoretically simulated studies regarding the increase of the electromagnetic field when gold nanorods with different aspect ratios undergo self-assembly in either perpendicular or parallel orientations to substrates. This research presents a novel and facile methodology for fabricating SERS nanosubstrates. This method entails self-assembling gold nanorods (AuNRs) with short and medium aspect ratios (ARs) through natural evaporation. By manipulating the water-to-ethanol ratios, we ascertain the appropriate conditions for the rational alignment of the nanorods in both perpendicular and parallel orientations relative to the silicon substrate. These nanosubstrates have been experimentally evaluated for their ability to improve the Surface-Enhanced Raman Scattering (SERS) performance, presenting a novel perspective in this field. In addition, a computational analysis employing the finite-difference time-domain (FDTD) method was conducted to elucidate the electromagnetic field generated by nanoarrays when subjected to incident light of varying wavelengths, including 532 nm, 638 nm, and 785 nm. Notably, the FDTD simulation outcomes indicated that gold nanorods (AuNRs) possessing an aspect ratio of 3.0 and nanogaps of 2.0 nm exhibited exceptional electromagnetic field characteristics when aligned parallel to the substrate under 532 nm laser illumination. Conversely, when the AuNRs were oriented perpendicular to the substrates, they produced lower EMFs upon interaction with excitation laser light. These findings can potentially contribute to the advancement of SERS nanosubstrate design.

Fabrication of Silicon Surface Microstructures via Vortex Femtosecond Laser Irradiation for Reusable Substrates in SERS Applications

Surface-enhanced Raman spectroscopy (SERS) is a key technique in analytical chemistry because of its exceptional sensitivity and specificity for detecting a broad spectrum of substances. Herein, a silicon (Si) substrate fabricated using vortex femtosecond laser beams in ambient air is proposed as an innovative, highly sensitive, and reusable platform for advanced SERS applications. The substrate has composite nanostructures adorned with bush-like formations on top of the elongated structures, which is a direct consequence of the orbital angular momentum of the vortex beam. Simulations conducted using COMSOL provide valuable insights into the distribution of hot spots and electromagnetic field across the substrate surface after gold nanoparticles deposition, underscoring the superior SERS detection capabilities of the fabricated substrate using vortex beams as compared to those processed by Gaussian beams. The vortex-fabricated substrate possesses remarkable reusability, stability, and time-resistance. It exhibited outstanding detection performance for malachite green and microcystin-LR, achieving limits of detection values of 3.91 pM and 2.69 pg·mL-1, respectively. Therefore, the Si substrates fabricated using a vortex femtosecond laser beam is an ideal candidate for advancing SERS sensors to new heights.

Determination of multiple analytes in urine using label-free SERS coupled with simple sample pretreatments

BACKGROUND

A key restriction of label-free surface-enhanced Raman spectroscopy (SERS) in analysis of objects with complex composition (including with several target analytes) is the competition of mixture components for interaction with SERS-active surface. This leads to poor selectivity of the analysis of such mixtures (e.g., body fluids) and the need to use advanced sample pretreatment procedures such as HPLC or TLC. Therefore, this work aims to develop a set of simple and fast pretreatment steps (dilution, pH correction, etc.) to increase the sorption of the target analyte, reduce the sorption of admixtures, and prevent suppression of the target analyte SERS signal.

RESULTS

We have developed label-free SERS assay suitable for the determination of three analytes (methotrexate, cephalosporin antibiotic, and creatinine) in one real urine sample as a model matrix with complex and deviating composition. The choice of drugs is justified by the need to monitor their concentration in urine during joint drug treatment of cancer patients with concomitant bacterial infection, while monitoring creatinine concentration helps to evaluate kidney function of the patients. Additionally, three cephalosporin representatives were used in the study to maximize versatility of the assay. As a results, the optimized pretreatment steps enable to eliminate the negative influence of excess of interferences (including other analytes) and achieve precise (≤12 % RSD) and accurate (88-111 % recovery) determination of several analytes in the therapeutically relevant ranges: 300-3000 μg mL-1 for creatinine, 20-200 μg mL-1 for methotrexate and cephalosporins.

SIGNIFICANCE

Therefore, in addition to reporting a new SERS assay for the analysis of body fluids, this study clearly demonstrates the importance of taking into account competitive adsorption processes on the SERS substrate surface. We suggest making this practice mandatory when developing any label-free SERS assay because it enables to maximize the selectivity and accuracy of the analysis as well as to simplify the analysis procedure.

Development of cellulose/ZnO based bioplastics with enhanced gas barrier, UV-shielding effect and antibacterial activity

Development of renewable and biodegradable plastics with good properties, such as the gas barrier, UV-shielding, solvent resistance, and antibacterial activity, remains a challenge. Herein, cellulose/ZnO based bioplastics were fabricated by dissolving cellulose carbamate in an aqueous solution of NaOH/Zn(OH)42-, followed by coagulation in aqueous Na2SO4 solution, and subsequent hot-pressing. The carbamate groups detached from cellulose, and ZnO which transformed from cosolvent to nanofiller was uniformly immobilized in the cellulose matrix during the dissolution/regeneration process. The appropriate addition of ZnO (below 10.67 wt%) not only improved the mechanical properties but also enhanced the water and oxygen barrier properties of the material. Additionally, our cellulose/ZnO based bioplastic demonstrated excellent UV-blocking capabilities, increased water contact angle, and enhanced antibacterial activity against S. aureus and E. coli, deriving from the incorporation of ZnO nanoparticles. Furthermore, the material exhibited resistance to organic solvents such as acetone, THF, and toluene. Indeed, the herein developed cellulose/ZnO based bioplastic presents a promising candidate to replace petrochemical plastics in various applications, such as plastic toys, anti-UV guardrails, window shades, and oil storage containers, offering a combination of favorable mechanical, gas barrier, UV-blocking, antibacterial, and solvent-resistant properties.

Source Tracing of Kidney Injury via the Multispectral Fingerprint Identified by Machine Learning-Driven Surface-Enhanced Raman Spectroscopic Analysis

Early diagnosis of drug-induced kidney injury (DIKI) is essential for clinical treatment and intervention. However, developing a reliable method to trace kidney injury origins through retrospective studies remains a challenge. In this study, we designed ordered fried-bun-shaped Au nanocone arrays (FBS NCAs) to create microarray chips as a surface-enhanced Raman scattering (SERS) analysis platform. Subsequently, the principal component analysis (PCA)-two-layer nearest neighbor (TLNN) model was constructed to identify and analyze the SERS spectra of exosomes from renal injury induced by cisplatin and gentamycin. The established PCA-TLNN model successfully differentiated the SERS spectra of exosomes from renal injury at different stages and causes, capturing the most significant spectral features for distinguishing these variations. For the SERS spectra of exosomes from renal injury at different induction times, the accuracy of PCA-TLNN reached 97.8% (cisplatin) and 93.3% (gentamicin). For the SERS spectra of exosomes from renal injury caused by different agents, the accuracy of PCA-TLNN reached 100% (7 days) and 96.7% (14 days). This study demonstrates that the combination of label-free exosome SERS and machine learning could serve as an innovative strategy for medical diagnosis and therapeutic intervention.

Silver nanoparticles modified sulfur-containing POSS polymer membrane substrate for adsorption and surface-enhanced Raman scattering analysis of chrysoidine in food samples

In analysis of complex samples, the stability and sensitivity of surface-enhanced Raman scattering (SERS) substrates may be compromised by matrix interference. To address this issue, a membrane substrate was prepared for fast enrichment, separation, and detection of chrysoidine all-in-one. The silver nanoparticles modified sulfur-containing POSS polymer (AgNPs/POSS-P-S) SERS membrane substrate was fabricated using polyhedral oligomeric silsesquioxane (POSS) as support materials. Through in-situ growth, AgNPs were uniformly modified on POSS-P-S to ensure the stability and SERS activity of the membrane substrate. The enhancement factor of the malachite green was up to 5.3 × 105. By loading the AgNPs/POSS-P-S on membrane, on the other hand, the SERS membrane substrate can also serve as an adsorption medium for separating chrysoidine from sample matrix. Furthermore, the specific sensing mechanism of AgNPs/POSS-P-S for chrysoidine was investigated and a fast, sensitive, and selective method for its quantification was established, with a linear range of 0.010-2.0 mg/L and the limits of detection at 3.7 μg/L. In addition, the SERS method was successfully applied for the analysis of chrysoidine in beverages and chili products with the recoveries in the range of 83.5%-113.4 % and the relative standard deviations in 3.2%-9.0 %. The proposed AgNPs/POSS-P-S membrane based SRES method has great potential for rapid chrysoidine analysis in food samples.

Peroxidase-like activity and mechanism of gold nanoparticle-modified Ti3C2 MXenes for the construction of H2O2 and ampicillin colorimetric sensors

Transition metal carbides modified by Au nanoparticles (Au/Ti3C2) were synthesized and developed as a colorimetric sensor for the determination of H2O2 and ampicillin. The surface electrical properties of Ti3C2 were changed, and Au nanoparticles (AuNPs) and gold growth solution were synthesized simultaneously. Au/Ti3C2 was obtained by seed growth method with AuNPs modified on the surface of transition metal carbides, nitrides or carbon-nitrides (Ti3C2 MXenes). The synthesized AuNPs and Ti3C2 had no peroxidase-like activity, but Au/Ti3C2 had. The peroxidase catalytic mechanism was due to electron transfer. The peroxidase activity of Au/Ti3C2 can be utilized for the determination of H2O2. The linear range of Au/Ti3C2 for H2O2 was 1-60 µM, and the detection limit was 0.12 µM (S/N = 3). A colometric sensor for ampicillin detection based on Au/Ti3C2 was further constructed since S in ampicillin formed an Au-S bond with Au/Ti3C2, leading to the weakening of its peroxidase-like property. The change of peroxidase-like property attenuated oxidation of TMB, and the ampicillin content was inversely proportional to the concentration of oxidized TMB, and the blue color of solution faded, which enabled the determination of ampicillin. The linear range for ampicillin was 0.005-0.5 µg mL- 1, and the detection limit was 1.1 ng mL- 1 (S/N = 3). The sensor was applied to the detection of ampicillin in milk and human serum.

Perovskite Nanocrystals: Superior Luminogens for Food Quality Detection Analysis

With the global limited food resources receiving grievous damage from frequent climate changes and ascending global food demand resulting from increasing population growth, perovskite nanocrystals with distinctive photoelectric properties have emerged as attractive and prospective luminogens for the exploitation of rapid, easy operation, low cost, highly accurate, excellently sensitive, and good selective biosensors to detect foodborne hazards in food practices. Perovskite nanocrystals have demonstrated supreme advantages in luminescent biosensing for food products due to their high photoluminescence (PL) quantum yield, narrow full width at half-maximum PL, tunable PL in the entire visible spectrum, easy preparation, and various modification strategies compared with conventional semiconductors. Herein, we have carried out a comprehensive discussion concerning perovskite nanocrystals as luminogens in the application of high-performance biosensing of foodborne hazards for food products, including a brief introduction of perovskite nanocrystals, perovskite nanocrystal-based biosensors, and their application in different categories of food products. Finally, the challenges and opportunities faced by perovskite nanocrystals as superior luminogens were proposed to promote their practicality in the future food supply.

All-inorganic lead halide perovskites for photocatalysis: a review

Nowadays, environmental pollution and the energy crisis are two significant concerns in the world, and photocatalysis is seen as a key solution to these issues. All-inorganic lead halide perovskites have been extensively utilized in photocatalysis and have become one of the most promising materials in recent years. The superior performance of all-inorganic lead halide perovskites distinguish them from other photocatalysts. Since pure lead halide perovskites typically have shortcomings, such as low stability, poor active sites, and ineffective carrier extraction, that restrict their use in photocatalytic reactions, it is crucial to enhance their photocatalytic activity and stability. Huge progress has been made to deal with these critical issues to enhance the effects of all-inorganic lead halide perovskites as efficient photocatalysts in a wide range of applications. In this manuscript, the synthesis methods of all-inorganic lead halide perovskites are discussed, and promising strategies are proposed for superior photocatalytic performance. Moreover, the research progress of photocatalysis applications are summarized; finally, the issues of all-inorganic lead halide perovskite photocatalytic materials at the current state and future research directions are also analyzed and discussed. We hope that this manuscript will provide novel insights to researchers to further promote the research on photocatalysis based on all-inorganic lead halide perovskites.

Design, Fabrication, and Applications of SERS Substrates for Food Safety Detection: Review

Sustainable and safe food is an important issue worldwide, and it depends on cost-effective analysis tools with good sensitivity and reality. However, traditional standard chemical methods of food safety detection, such as high-performance liquid chromatography (HPLC), gas chromatography (GC), and tandem mass spectrometry (MS), have the disadvantages of high cost and long testing time. Those disadvantages have prevented people from obtaining sufficient risk information to confirm the safety of their products. In addition, food safety testing, such as the bioassay method, often results in false positives or false negatives due to little rigor preprocessing of samples. So far, food safety analysis currently relies on the enzyme-linked immunosorbent assay (ELISA), polymerase chain reaction (PCR), HPLC, GC, UV-visible spectrophotometry, and MS, all of which require significant time to train qualified food safety testing laboratory operators. These factors have hindered the development of rapid food safety monitoring systems, especially in remote areas or areas with a relative lack of testing resources. Surface-enhanced Raman spectroscopy (SERS) has emerged as one of the tools of choice for food safety testing that can overcome these dilemmas over the past decades. SERS offers advantages over chromatographic mass spectrometry analysis due to its portability, non-destructive nature, and lower cost implications. However, as it currently stands, Raman spectroscopy is a supplemental tool in chemical analysis, reinforcing and enhancing the completeness and coverage of the food safety analysis system. SERS combines portability with non-destructive and cheaper detection costs to gain an advantage over chromatographic mass spectrometry analysis. SERS has encountered many challenges in moving toward regulatory applications in food safety, such as quantitative accuracy, poor reproducibility, and instability of large molecule detection. As a result, the reality of SERS, as a screening tool for regulatory announcements worldwide, is still uncommon. In this review article, we have compiled the current designs and fabrications of SERS substrates for food safety detection to unify all the requirements and the opportunities to overcome these challenges. This review is expected to improve the interest in the sensing field of SERS and facilitate the SERS applications in food safety detection in the future.