Recent advances in gold nanoparticles-based biosensors for food safety detection

PAT-on-a-chip: Miniaturization of analytical assays towards data-driven bioprocess development and optimization

The advancement of biopharmaceutical manufacturing, particularly continuous processing, has heightened the need for next-generation analytical tools approaching real-time monitoring of critical quality attributes (CQAs) and process parameters (CPPs). Current methods, primarily offline and labor-intensive, fail at delivering analytical information that can be used for process analytical technology (PAT) to control and optimize the manufacturing process, while also lacking the ability of multi-attribute monitoring, thus requiring a large number of samples (or sampling amount) to be collected. This work introduces the concept of PAT-on-a-chip, consisting of an integrated microfluidic platform designed to perform at-line analysis and characterization of cell culture samples in the context of monoclonal antibody (mAb) production. Specifically, a sample preparation-free miniaturized lectin-based assay was developed to measure levels of high mannose glycans and integrated with affinity-based assays to measure mAb titers and key impurities, namely Chinese hamster ovary (CHO) host cell proteins (HCP), within the same chip, resorting to a common colorimetric readout. The microfluidic chips were operated in a customized and integrated instrument comprising miniaturized photodiodes, connected to a graphical user interface for data recording and signal quantification. The PAT-on-a-chip unit allowed to achieve fit-for-purpose analyte quantification, while offering performance comparable to state-of-the-art offline analytical methods (Pearson R > 0.93), namely capillary electrophoresis with laser-induced fluorescence (CE-LIF) for glycan analysis, well plate immunoassays for CHO HCP and protein A HPLC for mAb titers, thus validating its potential to expand the modern PAT toolbox.

Aptamer-functionalized biomimetic supramolecular nanozyme constructed by dipeptide, glutaraldehyde and hemin and its excellent sensing performances for tetrodotoxin

Bioinspired nanozymes hold promise for simulating natural processes and creating optimized functional systems, but their application is hindered by limited catalytic activity and selectivity. These challenges can be addressed by reconstructing enzymatic active sites to enhance catalytic efficiency and integrating biological recognition units for specificity. In this work, we developed a peroxidase-mimicking nanozyme by stabilizing hemin on a supramolecular scaffold of diphenylalanine (FF) and glutaraldehyde (GA). To enable specific recognition, we conjugated a tetrodotoxin (TTX) aptamer, yielding the He@FF/GA-Apt composite nanozyme. This nanozyme demonstrated robust catalytic activity in 3,3',5,5'-tetramethylbenzidine (TMB) oxidation. The TTX aptamer conferred specific TTX recognition, with the aptamer-TTX complex blocking the nanozyme active site and reducing its activity. Based on this mechanism, we created a dual-mode TTX detection method using UV-vis spectroscopy and smartphone RGB analysis. The UV-vis mode achieved a linear range of 1.0-40.0 ng mL-1 and a limit of detection (LOD) of 0.61 ng mL-1, while the smartphone mode had a LOD of 1.43 ng mL-1 in a linear range of 2.0-40.0 ng mL-1. Both methods performed well in real samples, with recoveries of 96.29 %-102.57 % (UV-vis mode) and 92.07 %-109.46 % (RGB mode). In comparation, the UV-vis mode offers high sensitivity but requires lab equipment, whereas smartphone RGB mode enables rapid on-site detection despite a little lower sensitivity. This work provides a promising approach for developing target-specific nanozyme sensors.

Anti-fouling array paper-based device for rapid and accurate discrimination of foodborne pathogens in real samples

Foodborne pathogens contamination can cause serious food safety incidents. Early and rapid detection of foodborne pathogens is very important. Paper-based devices have been applied for on-site rapid detection of foodborne pathogens due to their cheapness and portability. However, the paper-based foodborne pathogen detection devices for real samples often receive interference, resulting in inaccurate detection results. In this study, bovine serum albumin (BSA) was modified on the surface of nitrocellulose membrane to construct anti-fouling sensing interface. Through array design, the anti-fouling array paper-based device (APAD) with multiple detection channels was constructed. The naked eye cut-off limits of the APAD were 102 colony forming units (cfu)/mL, 102 cfu/mL, and 103 cfu/mL for Staphylococcus aureus in orange juice, Escherichia coli O157: H7 in milk and orange juice, and Escherichia coli O157:H7 in soy sauce, respectively. The above results indicate that the APAD has good practical application potential in food safety.

An ultra-sensitive, intelligent platform for food safety monitoring: Label-free detection of illegal additives using self-assembled SERS substrates and machine learning

To overcome the limitations of SERS in food safety monitoring, particularly significant interference from citrate ions, this study introduces an intelligent SERS-based platform for food safety monitoring. The platform utilizes sodium borohydride to activate silver nanoparticles, and calcium ions can facilitate the nanoparticles aggregation to promote self-assembly and the form of "hotspots", but will also amplify citrate ions signal. Iodine ions was introduced to eliminate the interference of citrate signals and background fluorescence interference. The substrate achieved limit of detection of 100 fg/mL. Moreover, the innovative of spectral set "SERSome" enables comprehensive molecular fingerprint recognition, significantly enhancing accuracy. Furthermore, combined with machine learning enhances applicability for rapid and precise detection, and classification in food samples, and successfully applied to the monitoring of illegal additives in food. In summary, this system presents an intelligent, innovative detection platform for food safety, contributing to early prevention of foodborne illnesses.

Transformative biomedical devices to overcome biomatrix effects

The emergence of high-performance biomedical devices and sensing technologies highlights the technological advancements in the field. Recently during COVID-19 pandemic, biosensors played an important role in medical diagnostics and disease monitoring. In the past few decades, biosensors have made impressive advances in terms of sensing capability, methodology, and applications, and modern biosensors show higher performance and functionality compared to traditional biosensing platforms. Currently, various biomedical devices are already in the market or on the verge of commercialization, such as disposable paper-based devices, lab-on-a-chip devices, wearable sensors, and artificial intelligence-assisted systems, all contributing to the evolution of digital health. Despite the promising features of detection methods for developing practical biosensors, there are substantial barriers to the commercialization of biomedical devices. An important challenge is the matrix effect in the detection of clinical samples. Although achieving low limit of detection values under controlled laboratory conditions is feasible, maintaining performance in real clinical samples is difficult. Matrix molecules present in these samples can interact with analytes, potentially affecting sensitivity, specificity, and sensor response. Approaches to reduce nonspecific adsorption and cross-reactivity are imperative for improving sensor performance. The detection of diagnostic biomarkers in complex biological matrices often requires laborious sample preparation, which may affect accuracy and precision. In this review, we highlight the recent efforts to detect analytes in real samples, both invasively and noninvasively, and underline technological advancements that mitigate the biomatrix effects. We also discuss commercially available biosensors and technologies promising commercial success, highlighting their potential effect on healthcare and diagnostics.

Gold nanocubes etching enhanced light scattering immunoassay for highly sensitive detection of Staphylococcus aureus enterotoxin A

An innovative light scattering immunoassay was developed using an AuNPs etching strategy. Three types of anisotropic gold nanoparticles, including gold nanocubes, nanorods, and nanoflowers with distinct morphologies, were utilized to investigate how these morphological differences affect the sensitivity of light scattering signal transduction. Based on theoretical insights into light scattering and electromagnetic fields, gold nanocubes were identified as the optimal probes for enhancing light scattering signal transduction and were employed to construct an immunoassay for detecting staphylococcal enterotoxin A (SEA). The developed immunoassay achieved ultrahigh sensitivity for SEA detection in milk samples, with a detection limit of 10.39 pg mL-1, which is 190 times lower than that of conventional ELISA. The proposed immunoassay was validated across ten food samples, demonstrating high accuracy and robustness. Given these promising results, we believe this method has significant potential for screening trace levels of SEA in food products.

Nanomaterial-modified electrochemical aptasensors for tetracycline detection: a review

Excessive residues of tetracyclines in the livestock, food products and environment can lead to their accumulation in the human body through the food chain, unavoidably posing a threat to the human health. Therefore, it is essential to establish detection methods with high specificity, stability, and sensitivity. Among the numerous detecting techniques, electrochemical sensors with aptamers working as biorecognition elements have been increasingly applied to monitor tetracyclines. Notably, the synergy of a wide range of nanomaterials with aptamer-based sensors has improved the charge transfer efficiency and signal sensitivity. In this review, the advantages of aptamer-based recognition methods are discussed, and the measuring processes of electrochemical detection are introduced. Then, advances in electrochemical aptasensors used for detecting tetracyclines are summarized with an emphasis on the role of nanomaterials, such as carbon-based nanomaterials and gold-based nanomaterials, functioning as -transducing media and electrically conductive polymers. Finally, the current challenges and emerging trends in this field are also discussed, shedding light on the prospects for developing new aptasensors for tetracycline detection.

AI-Powered Innovations in Food Safety from Farm to Fork

Artificial intelligence is comprehensively transforming the food safety governance system by integrating modern technologies and building intelligent control systems that provide rapid solutions for the entire food supply chain from farm to fork. This article systematically reviews the core applications of AI in the orbit of food safety. First, in the production and quality control of primary food sources, the integration of spectral data with AI efficiently identifies pest and disease, food spoilage, and pesticide and veterinary drug residues. Secondly, during food processing, sensors combined with machine learning algorithms are utilized to ensure regulatory compliance and monitor production parameters. AI also works together with blockchain to build an immutable and end-point traceability system. Furthermore, multi-source data fusion can provide personalized nutrition and dietary recommendations. The integration of AI technologies with traditional food detection methods has significantly improved the accuracy and sensitivity of food analytical methods. Finally, in the future, to address the increasing food safety issues, Food Industry 4.0 will expand the application of AI with lightweight edge computing, multi-modal large models, and global data sharing to create a more intelligent, adaptive and flexible food safety system.

Emerging trends of biomedical nanotechnology in nutrition, health monitoring and disease diagnosis

The transdisciplinary nature of nanotechnology has facilitated its application across various fields, especially in biological sciences. The primary aim of this review is to consolidate the many facets of nanomedicine, theranostics, and nanotechnology in food preservation into a unified framework and to underscore established research methodologies in the medical domain. Nanoparticles serve a crucial function in improving the bioavailability of orally delivered bioactive substances. This review demonstrated that nanoparticles can enhance the bioavailability of micronutrients, such as vitamin B12, vitamin A, folic acid, and iron. New advances in nanotechnology have made big differences in finding pathogens and killing them specifically, helping people to get better health through medication delivery and imaging, improving food packaging better so it lasts longer, and making foods healthier overall. Nanotechnology currently enhances the safety of delivering highly hazardous medicines through the use of nanozymes that exhibit antioxidant and antibacterial characteristics. Moreover, wearable devices can identify significant alterations in vital signs, medical problems, and infections occurring within the body. We anticipate that these technologies will provide physicians with enhanced direct access to crucial information about the causes of changes in vital signs or diseases, as they are directly connected to the source of the problem. This review paper thoroughly examines the latest developments in nanomaterials and nanozymes as antimicrobial agents in food science and nutrition, wound healing, illness diagnostics, imaging, and potential future uses. The paper presents a concise and structured report on nanotechnology, which will be beneficial to researchers and scientists for future research opportunities.

Advancing oral cancer care: nanomaterial-driven diagnostic and therapeutic innovations

The advent of nanotechnology has significantly advanced the diagnosis and treatment of oral cancer, offering more precise and efficient therapeutic strategies. This review presents a comprehensive overview of recent developments in the application of nanotechnology to oral cancer management. It begins with an overview of the epidemiology of oral cancer and outlines current diagnostic and therapeutic methods. The classification and advantages of various nanomaterials are then introduced. The paper thoroughly explores the use of nanomaterials as drug delivery systems (DDSs), imaging contrast agents, and therapeutic tools, with particular emphasis on multifunctional nanoplatforms that integrate diagnostics and therapy. These platforms enable real-time monitoring and immediate therapeutic response, offering innovative approaches for early detection and intervention. Despite these promising advances, several challenges persist, including issues related to biocompatibility, clearance, targeting specificity, and clinical translation. The review concludes by highlighting current limitations and proposing future directions for the clinical application of nanotechnology in oral cancer treatment.

A template-free one-step synthesis of trimetallic nano-triangular structures significantly enhances the sensitivity of lateral flow immunoassays for acetamiprid detection

BACKGROUND

Acetamiprid (ACE), a commonly used insecticide, is widely applied in agricultural practices to control pests. However, its potential to leave residues in crops has raised significant concerns due to the associated risks to human health through food consumption. This has made the rapid, accurate, and on-site detection of ACE residues a pressing issue in the realm of global food safety. In the present study, we developed an innovative Platinum-Copper-Nickel Alloy Nano-Triangular Structure (PCNATS) to facilitate the rapid detection of ACE using a competitive assay. The PCNATS, featuring a high specific surface area and a complex three-dimensional structure, were conjugated with anti-ACE monoclonal antibodies to create advanced nanoprobes. ELISA results demonstrated that the PCNATS significantly improved the utilization efficiency of monoclonal antibodies, leading to enhanced sensing performance.

RESULTS

The PCNATS-based lateral flow immunoassay (PCNATS-LFIA) system displayed high sensitivity and accuracy, capable of quantitatively detecting ACE within 10 min. This method exhibited a limit of detection (LOD) of 3.6 ng/kg and a broad detection range from 0.05 pg/mL to 4 μg/mL. Compared to traditional gold nanoparticle-based lateral flow immunoassays (AuNPs-LFIA), the PCNATS-LFIA demonstrated a 1000-fold improvement in sensitivity. Furthermore, the assay showed strong correlation with the fitted standard curve when applied to real celery and papaya samples, achieving a satisfactory recovery rate ranging from 92.9 % to 109.9 % and 101.04 % to 115.76 %, with relative standard deviations (RSD) between 1.68 % to 7.73 % and 1.37 % to 3.02 %.

SIGNIFICANCE

Therefore, the PCNATS-LFIA system offers a portable, efficient, and cost-effective solution for the rapid, on-site detection of ACE residues in agricultural products.

Advancing Biosensing Frontiers Through Gold Nanoparticle Engineering: Synthesis Strategies and Detection Paradigms

Gold Nanoparticles (GNPs) play a pivotal role in nanobiotechnology because of their distinct physicochemical traits, such as optical properties, compatibility with biological systems, and their ability to be easily functionalized. The top-down and bottom-up approaches are for the synthesis of GNPs. There are various chemical, physical, and green synthesis techniques, such as chemical reduction, seed-mediated growth, physical ablation method, pyrolysis, sputtering, etc. are some methods for the synthesis of GNPs. The use of plants, algae, fungi, and other microorganisms has recently arisen as a new approach for the eco-friendly synthesis with precise control over NP size, shape, and surface properties. The functionalization strategies involving biomolecules, polymers, and ligands enhance their stability and target specificity, facilitating their integration into biosensors. The detection of biomolecules, pathogens, and environmental toxins with high sensitivity and accuracy is facilitated by multiple signals such as localized surface plasmon resonance (LSPR), alterations in color, and electrochemical characteristics. Furthermore, their role in point-of-care diagnostics, drug delivery, and imaging underscores their versatility in biomedical applications. This review provides a comprehensive overview of recent advancements in the synthesis, functionalization, and GNPs-based biosensors. In addition, the review highlights recent advancements, challenges, and future prospects of GNPs in biosensing and nanomedicine, offering an understanding of diagnostics and therapeutic monitoring. The key challenges include stability, reproducibility, and scalability, and the future focuses on green synthesis with enhanced sensitivity and multiplexed biosensing applications.

Nanoparticle-based biosensor integrated with multiple cross-displacement amplification for visual and rapid identification of hepatitis B virus and hepatitis C virus

Infection with hepatitis B virus (HBV) and hepatitis C virus (HCV) is a major contributor to liver-related morbidity and mortality worldwide. An accurate and rapid point-of-care (POC) diagnostic approach is the gateway for effective treatment and control of these infections. Here, for the first time, we integrated isothermal multiple cross-displacement amplification (MCDA) with a gold nanoparticle-based lateral flow biosensor (AuNPs-LFB) to successfully develop a novel HBV&HCV-MCDA-AuNPs-LFB assay for simultaneous accurate, sensitive, rapid, inexpensive, and visual identification of HBV and HCV agents. The two unique sets of MCDA degenerate primers were successfully designed targeting the S and 5' untranslated region (5'-UTR) genes from the major HBV genotypes (B, C, D, B/C recombinant, and C/D recombinant) and HCV subtypes in China (1b, 2a, 3a, 3b, and 6a), respectively. The optimal conditions for the MCDA reaction were confirmed to be 64°C for 35 min. The MCDA products were decoded visually using the AuNPs-LFB platform, which was devised for analyzing three targets, including HBV-MCDA, HCV-MCDA amplicons, and a chromatography control. The whole detection procedure, including rapid nucleic acid extraction (~10 min), MCDA reaction (35 min), and AuNPs-LFB interpretation (~2 min), can be completed within 50 min. The HBV&HCV-MCDA-AuNPs-LFB assay can detect the target genes (HBV-S and HCV-5'-UTR) with as low as 10 copies of gene-containing plasmid template per test and does not cross-react with other pathogens. Therefore, our preliminary results indicated that the HBV&HCV-MCDA-AuNPs-LFB assay developed in this study can potentially serve as a useful POC diagnostic tool for the identification of HBV and HCV infections.IMPORTANCEHepatitis B virus (HBV) and hepatitis C virus (HCV) infections have been regarded by the World Health Organization as major threats to human health, especially in low- and middle-income regions. Underdiagnosis of HBV/HCV is a particular challenge for achieving the World Health Organization's goal of eliminating HBV and HCV infections by 2030. Here, for the first time, we integrated isothermal multiple cross-displacement amplification (MCDA) with a gold nanoparticle-based lateral flow biosensor (AuNPs-LFB) to successfully develop a novel HBV&HCV-MCDA-AuNPs-LFB assay for simultaneous accurate, sensitive, rapid, inexpensive, and visual identification and differentiation of HBV and HCV agents.

A sensitive electrochemical DNA biosensor for detecting the genome of a plant growth-promoting bacteria

The challenge of increasing food production while maintaining environmental sustainability can be addressed by using biofertilizers such as Azospirillum, which can enhance plant growth and colonize more than 100 plant species. The success of this biotechnology depends on the amount of plant growth-promoting bacteria associated with the plant during crop development. However, monitoring bacterial population dynamics after inoculation requires time-consuming, laborious, and costly procedures. To address these issues, this study describes an effective electrochemical DNA biosensor to detect Azospirillum brasilense. The biosensor comprises a glassy carbon electrode modified with a nanocomposite based on carbon nanotubes and gold nanoparticles capped with 3-n-propylpyridinium chloride silsesquioxane, followed by the immobilization of a thiolated probe oligonucleotide that binds specifically to the A. brasilense genome (AZOgenome). The nanocomposite was characterized utilizing spectroscopic and morphological methods. Its presence on the biosensor's surface enhanced electrochemical responses due to its excellent electrocatalytic properties, as observed during electrochemical impedance spectroscopy and cyclic voltammetry experiments. The biosensor enabled the detection of AZOgenome after the hybridization event, which alters the electrochemical response of the electrode and was rapidly detected by square wave voltammetry. The detection range of the bacterial genome was 1.17 pmol L-1 to 146.8 pmol L-1, with LOD and LOQ of 0.261 and 0.322 pmol L-1, respectively, and sensitivity of -15.560 μA/log [AZOgenome] (pmol L-1). The biosensor showed good selectivity and reproducibility, with a coefficient of variation of -5.69 %, in addition to satisfactory sensitivity and stability for up to seven weeks. These promising analytical features allowed the quantification of A. brasilense in low concentrations in soil metagenomic DNA samples.

Ultrasensitive colorimetric detection of deoxynivalenol in infant milk powder based on the inhibitory effect of silver ions on the peroxidase-like activity of Ni@Pt nanoparticles

Deoxynivalenol, a hazardous mycotoxin, poses significant health risks to humans and animals, necessitating highly sensitive detection methods due to its low abundance in food. Herein, we present a colorimetric sensing strategy for deoxynivalenol detection based on the inhibitory effect of silver ions on the peroxidase-like activity of Ni@Pt nanoparticles. Silver ions adsorb onto the surface of Ni@Pt nanoparticles, blocking the active site and consequently impeding their catalytic activity. By integrating antigen-antibody interactions with the biotin-streptavidin system, a specific aptamer can be introduced to chelate silver ions, thereby modulating the activity of Ni@Pt nanoparticles for signal readout through the 3,3',5,5'-tetramethylbenzidine/hydrogen peroxide system. This method achieves a detection limit of 47.4 pg/mL, surpassing traditional enzyme-linked immunosorbent assays and rivaling the sensitivity of precision instrumental analysis. Furthermore, this colorimetric method demonstrates robust recovery and has been successfully challenged deoxynivalenol detection in infant milk powder samples, highlighting its potential for practical applications.

IoT-Enabled Biosensors in Food Packaging: A Breakthrough in Food Safety for Monitoring Risks in Real Time

The integration of biosensors and the Internet of Things (IoT) in food packaging is gaining significant interest in rapidly enhancing food safety and traceability worldwide. Currently, the IoT is one of the most intriguing topics in the digital and virtual world. Biosensors can be integrated into food packaging to monitor, sense, and identify early signs of food spoilage or freshness. When coupled with the IoT, these biosensors can contribute to data transmission via IoT networks, providing real-time insights into food storage and transportation conditions for stakeholders across each stage of the food supply chain, facilitating proactive decision-making practices. The technologies of combining biosensors with IoT could leverage artificial intelligence (AI) to enhance food safety, quality, and security in food industries, compared to conventional existing food inspection technologies, which are limited to assessing weight, volume, color, and physical appearance. This review focused on highlighting the latest and existing advancements, identifying the knowledge gaps in the applications of biosensors and the IoT, and exploring their opportunities to shape future food packaging, particularly in the context of 21st-century food safety. The review also aims to investigate the role of the IoT in creating smart food ecosystems and examines how data transmitted from biosensors to IoT systems can be stored in cloud-based platforms, in addition to addressing upcoming research challenges. Concerns of data privacy, security, and regulatory compliance in implementing the IoT and biosensors for food packaging are also addressed, along with potential solutions to overcome these barriers.

Rapid and sensitive detection of malachite green by multifunctional octahedron UiO- 66-NH2/Fe3O4/Ag SERS substrate

Multifunctional nanocomposites have attracted extensive attention in the design of new SERS substrates. In this work, a metal-organic framework (MOF) modified with Ag nanoparticles (Ag NPs) and cysteine functionalized Fe3O4 (UiO-66-NH2/Fe3O4/Ag) was prepared as a SERS substrate (UFAs). The substrate combines the enrichment ability of UiO-66-NH2, the magnetic separation ability of Fe3O4, and the localized surface plasmon resonance (LSPR) effect of Ag NPs to achieve efficient detection of the target analyte. The results of adsorption kinetics showed that the adsorption process of malachite green (MG) was mainly dominated by chemical adsorption. In addition, we further explored the detection mechanism of UFAs for MG. UFAs enriched cation analytes such as MG through π-π stacking and electrostatic interaction and performed SERS detection. The UFA SERS substrate exhibits good detection sensitivity for MG, with a limit of detection (LOD) of 1.35 × 10-10 M (at 1619 cm-1), and the SERS substrate has good uniformity and stability. The SERS substrate was applied to the detection of MG in aquaculture water. The recovery of MG in the sample was 91.2-105%, and the relative standard deviation (RSD) was 3.76-6.06%. This high-performance UFA SERS substrate also has great potential for the detection of food and other environmental pollutants in practical applications.

Radial SERS acquisition on coffee ring for Serum-based breast cancer diagnosis through Multilayer Perceptron

The coffee-ring effect, involving spontaneous solute separation, has demonstrated promising potential in the context of patient serum analysis. In this study, an approach leveraging the coffee-ring-based analyte redistribution was developed for spectral analysis of surface-enhanced Raman scattering (SERS). By performing radical SERS scanning through the coffee-ring area and sampling across the coffee ring, complicated chemical information was spatially gathered for further spectra analysis. The corresponding application in classification of serum samples from breast cancer patients was also proposed. A simulated serum environment was constructed by mixing phenylalanine, hypoxanthine, and bovine serum albumin (BSA), yielding the coffee-ring patterns along with gold nanoparticles. Distinct divergence in the distributions between hypoxanthine and phenylalanine within the rings were characterized, which is attributed to the inherent electrostatic properties of the noble metal colloid and the interactions among different solvents. Subsequently, this method was applied to serum samples from patients diagnosed with the four breast cancer subtypes. By preparing serum with SERS substrates and forming the coffee-ring patterns, radial SERS scanning was conducted across the rings. The acquired spectra were spatially segmented and processed by employing a multilayer perceptron for learning and prediction. The classification results demonstrated a predictive accuracy of 85.7% in distinguishing among the four breast cancer subtypes, highlighting the feasibility and effectiveness of the coffee-ring assisted radial SERS analysis.

Enhanced Detection of Enrofloxacin in Seawater Using a Newly Selected Aptamer on a Graphite Oxide-Based Biosensor

Developing aptasensors offers several advantages including sensitivity, selectivity, cost-effectiveness, and speed over traditional analytical techniques for antibiotic detection. We have successfully identified Enro_ap3, a 30-mer enrofloxacin-binding aptamer with micromolar binding affinity, through an optimized Capture-SELEX platform. Compared to other reported enrofloxacin-binding aptamers, this shorter aptamer not only streamlines the design process but also eliminates the common issue of strong nonspecific binding to the GO surface, thereby improving the overall detection capabilities of the biosensor (GO-Enro_ap3-FAM). This GO aptasensor demonstrated remarkable selectivity by effectively distinguishing enrofloxacin from different structurally diverse antibiotics. The sensor boasts a LOD of 32.15 μg/mL, 2.5 times more sensitive than the original 30-mer, with recoveries of 74%-92% and relative standard deviations of 6.3%-12.5% in seawater samples spiked with enrofloxacin. Furthermore, the GO aptasensor's detection capabilities were found to be on par with traditional LC-MS/MS techniques, exhibiting no significant differences in recovery rates even in complex matrices. The sensor's performance remained consistent across variations in salinity, acidity, and total organic carbon concentrations in seawater samples collected from different locations, underlining its robustness in diverse environmental conditions and its suitability for real-world seawater monitoring applications. Our findings highlight the importance of the aptamer's chain length and its binding affinity toward the target after immobilization on the GO substrate. These factors significantly impact the performance of GO aptasensors in seawater. Overall, the GO aptasensor provides a well-balanced approach, combining sensitivity, environmental adaptability, and practical usability for detecting pharmaceutical contaminants, such as antibiotics, in marine environments.

Disodium EDTA-capped AuNP-engineered cotton pad as a colorimetric probe for formalin detection

Formalin, an organic chemical containing a mixture of carbon, hydrogen, and oxygen, is a formaldehyde solution in water that is widely used as a preservative because of its antibacterial qualities. Despite being used to extend the shelf life and conceal product deterioration, it may be harmful to customers. In light of these factors, a portable, sensitive, accurate, and user-friendly platform for formalin detection is suggested here. The present study utilizes a colorimetric approach that involves the use of disodium ethylenediaminetetraacetic acid (EDTA)-capped gold nanoparticles (AuNPs) and a smartphone. A cotton pad with AuNa2EDTA integrated served as the substrate for formalin adsorption. The colorimetric image is then converted into RGB values using the graphical editor software, GNU Image Manipulation Program (GIMP), to detect formalin. A noticeable color shift was seen during the detection process: the hue changed from red-wine to purplish-blue as the formalin content rose, indicating the development of the AuNa2EDTA-HCHO complex. This result provides a low detection limit of 0.11 μM and a sensitive linear correlation between 1/R values and various formalin concentrations, with a linear fit coefficient of 0.99607. The present study represents the first attempt, to the best of our knowledge, to report on the experimental activation energy of gold nanoparticles capped with Na2EDTA as well as the application of this nanostructure as a formalin detection platform. The developed system has a great potential of being used in clinical settings for the detection of formalin.

Resonance light scattering combined with miniaturized Thermal-Assisted Purge-and-Trap device for screening of hydrochloride drugs

Resonance Light Scattering (RLS) is a sensitive analytical technology hindered by its susceptibility to impurities in complex samples. This study introduces a combination of RLS with a high-efficiency sample preparation device, the Miniaturized Thermal-Assisted Purge-and-Trap (MTAPT), enhancing RLS's effectiveness in complex sample analysis. Specifically, we utilized MTAPT-RLS for the indirect screening of illegal hydrochloride drug additions in health products, based on three considerations: the transformation of bound HCl in hydrochloride drugs into volatile HCl under strong acid and heat; the minimal Cl content in health products for taste purposes; and the detectability of Cl ions by RLS upon the addition of AgNO3 and a stabilizer. Employing RLS, this method quantifies Cl elements via fluorescence signals, achieving a linear response (R = 0.9984) across 5.0-80.0 μg/mL and a recovery rate of 94.1-114.0 % across three sample types. With a detection limit of 2.0 μg/mL, this approach exceeds traditional rapid detection methods in speed and sensitivity, offering substantial benefits for food safety monitoring. Additionally, we developed a smartphone-based detection system utilizing RGB signal changes captured by smartphone cameras, coupled with a custom app. This system shows a linear response (R = 0.9888) within the same concentration range and detection limit. Notably, the green light source provided the highest sensitivity, aligning with the RLS peak at approximately 520 nm. With its excellent portability, this method is well-suited for on-site rapid detection, independent of bulky analytical instruments.

Nanobody-Based Immunoassays for the Detection of Food Hazards-A Review

Food safety remains a significant global challenge that affects human health. Various hazards, including microbiological and chemical threats, can compromise food safety throughout the supply chain. To address food safety issues and ensure public health, it is necessary to adopt rapid, accurate, and highly specific detection methods. Immunoassays are considered to be an effective method for the detection of highly sensitive biochemical indicators and provide an efficient platform for the identification of food hazards. In immunoassays, antibodies function as the primary recognition elements. Nanobodies have significant potential as valuable biomolecules in diagnostic applications. Their distinctive physicochemical and structural characteristics make them excellent candidates for the development of reliable diagnostic assays, and as promising alternatives to monoclonal and polyclonal antibodies. Herein, we summarize a comprehensive overview of the status and prospects of nanobody-based immunoassays in ensuring food safety. First, we begin with a historical perspective on the development of nanobodies and their unique characteristics. Subsequently, we explore the definitions and boundaries of immunoassays and immunosensors, before discussing the potential applications of nanobody-based immunoassays in food safety testing that have emerged over the past five years, and follow the different immunoassays, highlighting their advantages over traditional detection methods. Finally, the directions and challenges of nanobody-based immunoassays in food safety are discussed. Due to their remarkable sensitivity, specificity and versatility, nanobody-based immunoassays hold great promise in revolutionizing food safety testing and ensuring public health and well-being.

Water-stable Eu(III) coordination polymer-based ratiometric fluorescence sensor integrated with smartphone for onsite monitoring of doxycycline hydrochloride in milk

The widespread misuse of doxycycline hydrochloride (Dox) in livestock farming has necessitated the development of rapid and reliable methods for monitoring its residues in food products. Herein, a water-stable europium coordination polymer-Eu(C2O4)1.5(H2O)ₙ (Eu-CP) with a layered structure was synthesized via a one-step hydrothermal approach. Leveraging its dual-emission properties (455 nm ligand-centered blue emission and 615 nm Eu(III)-based red emission), we engineered a ratiometric fluorescence sensor (I₆₁₅/I₄₅₅) for Dox detection. The sensing mechanism involves synergistic effects of the antenna effect and Dox@Eu-CP complexation, enabling selective Dox recognition with a wide linear range (10-100 μM) and a low detection limit (0.46 μM, S/N = 3). To facilitate onsite analysis, a smartphone-integrated platform was developed, translating the Dox concentration-dependent color transition (blue → red) into quantifiable R/G values via a custom Android application. Practical applicability was demonstrated in milk samples, achieving recoveries of 82.4-119.4% (fluorescence) and 87.8-113.3% (smartphone) with RSD < 5%. This work pioneers the integration of lanthanide coordination polymers with portable digital detection, offering a green and visual strategy for antibiotic residue monitoring in food safety.

Nanotechnology-Based Modern Biosensors for the Detection of SARS-CoV-2 Virus

The emergence of the COVID-19 pandemic has pointed out the urgent need for rapid and accurate diagnostic tools to detect the SARS-CoV-2 virus. Nanotechnology-based biosensors have emerged as a promising solution due to their high sensitivity, specificity, and speed in detecting biological molecules. This article focuses on the advancements in using nanotechnology for the development of modern biosensors tailored for the detection of the SARS-CoV-2 virus. Various nanomaterials, such as quantum dots, metallic nanoparticles, and nanowires, have been harnessed to enhance the performance of biosensors, offering improved detection limits and specificity. Besides this, innovative detection platforms, such as field-effect transistors, surface plasmon resonance, and electrochemical sensors, have revolutionized the landscape of SARS-CoV-2 diagnostics. These nanotechnology-based biosensors demonstrate the potential for point-of-care testing, enabling rapid and on-site detection with minimal sample preparation. The scalability, cost-effectiveness, and portability of these biosensors make them suitable for mass screening efforts in various healthcare settings, including hospitals, clinics, and community centers. The development of reliable biosensors for SARS-CoV-2 detection aligns with global efforts to curb the spread of the virus through early identification and containment strategies.

Nanobiosensors Enable High-Efficiency Detection of Tuberculosis Nucleic Acid

Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis (Mtb), with a complex pathogenesis that poses a long-term threat to human health globally. Early and accurate diagnosis of TB provides a critical window for timely and effective treatment. The development of nucleic acid testing (NAT) based on polymerase chain reaction (PCR) has greatly improved the diagnostic efficiency of TB. However, balancing detection accuracy, efficiency, and cost in TB NAT remains challenging. Functionalized nanomaterials-based nanobiosensors have demonstrated exceptional performance in detecting TB nucleic acid by integrating their unique physicochemical properties with diverse biological probes that exploit Mtb characteristics to effectively amplify biological signals. Compared to traditional NAT, nanobiosensors simplify nucleic acid detection, improve accuracy, and reduce reliance on external conditions, thereby contributing to more immediate and accurate TB diagnosis. In this perspective, we provide a comprehensive summary and discussion on current strategies for detecting Mtb biomarkers using nucleic acid along with novel solutions for TB diagnosis. Additionally, we explore the advantages and challenges associated with applying nanotechnology to the clinical management of TB, particularly point-of-care testing (POCT).

One-Step Green Hydrothermal-Assisted Synthesis of Carbon Quantum Dots From Robinia hispida L. Flowers, and Flourimetric Detection of Au3+ Ions in Aqueous Media

Water-soluble fluorescent carbon quantum dots (CQDs) were synthesized via a single-step, eco-friendly hydrothermal process using Robinia hispida L. flowers as a novel carbon source. Advanced characterization techniques (HRTEM, XRD, XPS, FTIR, UV-vis, and fluorescence spectroscopy) revealed spherical CQDs with an average size of 3.96 ± 0.83 nm and a quantum yield of 5.13%. Under 365 nm UV light, the CQDs emitted blue fluorescence. Fluorescence quenching studies with various metal ions showed a significant 93.5% reduction in FL intensity with 500 μM Au3+ ions. At pH 7.0, a linear detection range of 0.5-3.5 μM was achieved, with limits of detection (LOD) and quantification (LOQ) of 0.4 and 1.2 μM, respectively. The non-functionalized CQDs effectively detected Au3+ ions in tap, drinking, and river water, acidic mine drainage (sludge), and a standard reference material (CRMSA-C Sandy Soil C), achieving spike recoveries of 96.06%-101.71% with variability below 4.13%.

Enhanced nanobody-driven bioluminescent immunoassay for rapid parathion detection using engineered split-nanoluciferase

In this work, with parathion, a typical forbidden organophosphate pesticide as target drug, an enhanced nanobody-driven bioluminescent immunoassay based on the engineered split-nanoluciferase (NanoLuc) was proposed. Concretely, through labeling 11S and β10, two split-NanoLuc units onto the anti-parathion nanobody (Nb) VHH9 and the artificial antigen H1 coupled with carrier protein ovalbumin (H1-OVA) respectively, an NanoLuc Binary Technology (NanoBiT) system was firstly developed in the form of homogeneous immunoassay, in which the luminescence signal was produced by the reassembled NanoLuc after the combination of the 11S-fused VHH9 and β10-labeled H1-OVA. Subsequently, in order to enhance the signal-to-noise (S/N) ratio, a novel strategy of splitting 11S into two smaller subunits Δ11S and β9 was adopted so then an NanoLuc Ternary Technology (NanoTeT) system based on tri-part components of β9-fused VHH9, β10-labeled H1-OVA and Δ11S was successfully established. The results showed that the maximum half inhibition concentration (IC50) for parathion can be as low as 2.04 ng/mL, 3.2-fold and 4.2-fold improved than that of the NanoBiT system and indirect competitive enzyme-linked immunosorbent assay (ic-ELISA). Meanwhile, the detection range was from 0.19 ng/mL to 22.11 ng/mL. More importantly, this method required simply a one-step incubation with all reagents mixed together, and the total time used in detection was only 10 min, 7-fold faster than ic-ELISA. Finally, the average recoveries for vegetable samples were from 84.8% to 122% with the coefficient of variance (CV) below 15%. Overall, this study provides a new platform for homogeneous immunoassay of the small-molecule contaminants.

Green synthesis of silica-coated gold nanoparticles employing femtosecond laser, solid targets, and water

Gold nanoparticles are widely used in biomedical applications due to their unique properties. However, traditional synthesis methods generate contaminants that cause cytotoxicity and compromise the biocompatibility of the nanomaterials. Therefore, green synthesis methods are essential to produce pure and biocompatible nanoparticles, ensuring their effectiveness in biomedical applications. This study introduces a novel approach for synthesizing silica-coated gold nanoparticles (AuNP@SiO₂) using femtosecond laser ablation in water, eliminating the need for chemical reagents. The process involves three key laser-based steps: Si ablation, SiNP@SiO₂ fragmentation, and Au ablation, all conducted in a liquid environment. The resulting AuNP@SiO₂ were characterized using transmission electron microscopy (TEM), UV-Vis absorption spectroscopy, dynamic light scattering (DLS), X-ray diffraction (XRD), and zeta potential measurements. The results demonstrated that the AuNP@SiO₂ nanoparticles exhibit high colloidal stability, with a notably negative zeta potential of (-72.0 ± 0.3) mV, effectively preventing particle aggregation. TEM analysis confirmed predominantly spherical nanoparticles with an average diameter of (15.87 ± 0.70) nm, encapsulated by a SiO₂ layer ranging from 1 to 3 nm in thickness. The synthesis approach produced nanoparticles with an average size distribution below 35 nm. This green synthesis method not only produces stable and well-characterized AuNP@SiO₂ nanoparticles but also represents a significant step towards more sustainable nanomaterial production, with promising implications for biomedical applications.

Advancing foodborne pathogen detection: a review of traditional and innovative optical and electrochemical biosensing approaches

Foodborne diseases are a significant cause of morbidity (600 million cases) and mortality (420,000 deaths) worldwide every year and are mainly associated with pathogens. Besides the direct effects on human health, they have relevant concerns related to financial, logistics, and infrastructure for the food and medical industries. The standard pathogen identification techniques usually require a sample enrichment step, plating, isolation, and biochemical tests. This process involves specific facilities, a long-time analysis procedures, and skilled personnel. Conversely, biosensors are an emerging innovative approach to detecting pathogens in real time due to their portability, specificity, sensitivity, and low fabrication costs. These advantages can be achieved from the synergistic work between nanotechnology, materials science, and biotechnology for coupling biomolecules in nano-matrices to enhance biosensing performance. This review highlights recent advancements in electrochemical and optical biosensing techniques for detecting bacteria and viruses. Key properties, such as detection limits, are examined, as they depend on factors like the design of the biorecognition molecule, the type of transducer, the target's characteristics, and matrix interferences. Sensitivity levels reported range from 1 to 1 × 10⁸ CFU/mL, with detection times spanning 10 min to 8 h. Additionally, the review explores innovative approaches, including biosensors capable of distinguishing between live and dead bacteria, multimodal sensing, and the simultaneous detection of multiple foodborne pathogens - emerging trends in biosensor development.

A Label-Free Colorimetric Aptasensor for Flavokavain B Detection

Flavokavain B (FKB), a hepatotoxic chalcone from Piper methysticum (kava), has raised safety concerns due to its role in disrupting redox homeostasis and inducing apoptosis in hepatocytes. Conventional chromatographic methods for FKB detection, while sensitive, are costly and impractical for field applications. In this work, DNA aptamers were selected using the library-immobilized method and high-throughput sequencing. Three families of aptamers were obtained, and the best one named FKB-S showed a dissociation constant (KD) of 280 nM using microscale thermophoresis. To demonstrate its practical utility, a rapid and label-free colorimetric aptasensor was developed based on aptamer-induced gold nanoparticle aggregation. This assay achieved a detection limit of 150 nM (43.46 ng/mL) and provided results within 10 min. Compared to traditional chromatographic methods, the aptasensor offers a simple, cost-effective, and equipment-free approach for on-site FKB detection, making it a promising tool for the quality control and safety monitoring of kava-based products in diverse environments.

Differential insulin response characteristics of graphene oxide-gold nanoparticle composites under varied synthesis conditions

The structural alterations in the constituent materials of nanocomposites such as graphene nanocomposites typically induce changes in their properties including mechanical, electrical, and optical properties. Therefore, by altering the preparation conditions of nanocomposites and investigating their responsiveness to basic biomolecules (such as proteins), it is possible to explore the application potentials of the composites and guide development of new nanocomposite preparation. In this study, different composites of graphene oxide and gold nanoparticles (AuNPs/GO) were obtained by varying the volumes of reducing agents used in the one-pot hydrothermal method. Insulin was chosen as a basic protein to study the response characteristics of AuNPs/GO under different preparation conditions. Optical responses of these composites to pure insulin and various commercial insulin types were all explored for the first time. The results indicated that AuNPs/GO could optically respond to insulin, including pure insulin and various types of commercial insulin, and changes in the preparation conditions could really influence this response. Moreover, optimal preparation conditions could be determined by an optical method for the largest responses of the nanocomposites to insulin. Based on previous research and the results of this study, it is speculated that the responses of AuNPs/GO to insulin may attribute to glutamic acids, asparagines, and glutamines on insulin, which may interact with AuNPs/GO, particularly with the AuNPs in the composites. Besides, the AuNPs/GO could exhibit relatively stable responses to various commercial insulin types and detect the concentration of specific branded commercial insulin with smaller errors. In summary, this study demonstrated the application potential of AuNPs/GO in areas such as drug testing and production, while also furnishing an experimental foundation and direction for further applications of AuNPs/GO in biosensing and biomolecule detection.

Recent advances in gold Janus nanomaterials: Preparation and application

Gold Janus nanomaterials have a tremendous significance for the novel bifunctional materials, significantly expanding the application scope of gold nanomaterials, especially Janus gold-thiol coordination polymer due to their exceptional biological characteristics, stability, plasmon effect, etc. The recent research on Janus gold nanoparticles and monolayer films of preparation and application has been summarized and in this review. To begin, we briefly introduce overview of Janus nanomaterials which received intense attention, outline current research trends, and detail the preparation and application of gold nanomaterials. Subsequently, we present comprehensively detailing fabrication strategies and applications of Janus gold nanoparticles. Additionally, we survey recent studies on the Janus gold nano-thickness films and point out the outstanding advantage of application on the tunable surface plasmon resonance, high sensitivity of surface-enhanced Raman scattering and electrical analysis fields. Finally, we discuss the emerging trends in Janus gold nanomaterials and address the associated challenges, thereby providing a comprehensive overview of this area of research.

Including the rare cubane cluster cobalt coordination polymer as the fluorescent sensing material for selectively and sensitively detecting the nitrofurantoin antibiotic

More and more attention has been paid to food safety. Due to the overuse and misuse of antibiotics, the problem of antibiotic residues in animal food is one of the important challenges to ensure food safety. The development of a feasible strategy to detect antibiotic residues in animal food has become desirable. In this paper, we creatively synthesize a water-stable fluorescence sensing material, namely, Co(Ⅱ)-Coordination polymer [Co2(CA) (L)0.5 (H2O)3] n (L = 1,4-bis(imidazole-1-ylmethyl) benzene, CA= Citric acid). The single crystal X-ray diffraction shows that it crystallizes in tetragonal space group I-4. It is worth mentioning that there exists the rare Co4(μ3-O)4 cubane cluster structure and Co8 cluster units. Those adjacent Co8 cluster units are connected into an infinite two-dimensional net structure by four flexible bridged L ligands. Finally, the Co(Ⅱ)-Coordination polymer (CP) further develops into the three-dimensional supramolecular structure via the hydrogen bonds of O-H⋯O and C-H⋯O. It could selectively detect the antibiotic-nitrofurantoin (NFT) residue by way of fluorescence quenching, Co-CP for the detection of NFT shows broad linearity from 0 to 200 μM, with a detection limit of 0.13 μM and strong anti-interference ability. It is used to detect the NFT residual of tap water and milk with a spiked recovery of 86.35-112.47 %.

Enhanced immunochromatographic assay using multifunctional gold@iridium nanoflower with colorimetric photothermal catalytic activity for the detection of staphylococcal enterotoxin B

The development of a rapid, sensitive, and accurate screening method for staphylococcal enterotoxin B (SEB) in food is urgently needed because trace amounts of SEB can pose a serious threat to human health. Here, we developed a ultrasensitive triple-modal immunochromatographic assay (ICA) for SEB detection. The AuNFs@Ir nanoflowers exhibited enhanced colorimetric, photothermal, and catalytic performance by modulating the sharp branching structure of the gold nanoflowers and depositing high-density Ir atoms. Subsequently, the combination of AuNFs@Ir and ICA promoted colorimetric, catalytic amplified colorimetric, and photothermal-assisted quantitative detection. The results showed detection limits of 0.175, 0.0188, and 0.043 ng mL-1 in the colorimetric/photothermal/catalytic mode, which increased the sensitivity by 16.5-fold, 153.7-fold, and 67.2-fold, respectively, compared with the AuNPs-ICA. Furthermore, the proposed strategy was verified in milk, milk powder, pork, and beef successfully. This strategy improves significantly the sensitivity, accuracy, flexibility and offers an effective insight for foodborne bacterial toxin monitoring.

Foodborne pathogen detection using surface acoustic wave biosensors: a review

This paper summarizes several attractive surface acoustic wave (SAW) biosensors, including Love-wave sensors, dual-channel SAW sensors, langasite SAW sensors, and SAW syringe filters. SAW sensors with different piezoelectric materials and high-frequency SAW sensors used for identifying the food pathogenic bacteria Escherichia coli (E. coli) are discussed together with the examples of methods based on such sensing technology that have been effectively utilized in diagnostics and epidemiological research. This review also emphasizes some of the limitations of using these biosensors, which have prompted the increased need for more rapid, sensitive, selective, portable, power-efficient, and low-cost methods for detecting these pathogens. It is envisioned that SAW devices will have remarkable significance in the future.

Rapid and Specific Detection of Bacillus cereus Using Phage Protein-Based Lateral Flow Assays

Rapid and precise diagnostic techniques are essential for identifying foodborne pathogens, including Bacillus cereus (B. cereus), which poses significant challenges to food safety. Traditional detection methods are limited by long incubation times and high costs. In this context, gold nanoparticle (AuNP)-based lateral flow assays (LFAs) are emerging as valuable tools for rapid screening. However, the use of antibodies in LFAs faces challenges, including complex production processes, ethical concerns, or variability. Here, we address these challenges by proposing an innovative approach using bacteriophage-derived proteins for pathogen detection on LFAs. We used the engineered endolysin cell-wall-binding domain (CBD) and distal tail proteins (Dit) from bacteriophages that specifically target B. cereus. The protein-binding properties, essential for the formation of efficient capture and detection biointerfaces in LFAs, were extensively characterized from the microstructural to the LFA device level. Machine-learning models leverage knowledge of the protein sequence to predict advantageous protein orientations on the nitrocellulose membrane and AuNPs. The study of the biointerface binding quantified the degree of attachment of AuNPs to bacteria, providing, for the first time, a microscopic model of the number of AuNPs binding to bacteria. It highlighted the binding of up to one hundred 40 nm AuNPs per bacterium in conditions mimicking LFAs. Eventually, phage proteins were demonstrated as efficient bioreceptors in a straightforward LFA prototype combining the two proteins, providing a rapid colorimetric response within 15 min upon the detection of 105 B. cereus cells. Recombinantly produced phage binding proteins present an opportunity to generate a customizable library of proteins with precise binding capabilities, offering a cost-effective and ethical alternative to antibodies. This study enhances our understanding of phage protein biointerfaces, laying the groundwork for their utilization as efficient bioreceptors in LFAs and rapid point-of-care diagnostic assays, thus potentially strengthening public health measures.

Gold Nanoprobes for Robust Colorimetric Detection of Nucleic Acid Sequences Related to Disease Diagnostics

Gold nanoparticles (AuNPs) are highly attractive for applications in the field of biosensing, particularly for colorimetric nucleic acid detection. Their unique optical properties, which are highly sensitive to changes in their environment, make them ideal candidates for developing simple, rapid, and cost-effective assays. When functionalized with oligonucleotides (Au-nanoprobes), they can undergo aggregation or dispersion in the presence of complementary sequences, leading to distinct color changes that serve as a visual signal for detection. Aggregation-based assays offer significant advantages over other homogeneous assays, such as fluorescence-based methods, namely, label-free protocols, rapid interactions in homogeneous solutions, and detection by the naked eye or using low-cost instruments. Despite promising results, the application of Au-nanoprobe-based colorimetric assays in complex biological matrices faces several challenges. The most significant are related to the colloidal stability and oligonucleotide functionalization of the Au-nanoprobes but also to the mode of detection. The type of functionalization method, type of spacer, the oligo-AuNPs ratio, changes in pH, temperature, or ionic strength influence the Au-nanoprobe colloidal stability and thus the performance of the assay. This review elucidates characteristics of the Au-nanoprobes that are determined for colorimetric gold nanoparticles (AuNPs)-based nucleic acid detection, and how they influence the sensitivity and specificity of the colorimetric assay. These characteristics of the assay are fundamental to developing low-cost, robust biomedical sensors that perform effectively in biological fluids.

Gold Nanoparticles: Multifunctional Properties, Synthesis, and Future Prospects

Gold nanoparticles (NPs) are among the most commonly employed metal NPs in biological applications, with distinctive physicochemical features. Their extraordinary optical properties, stemming from strong localized surface plasmon resonance (LSPR), contribute to the development of novel approaches in the areas of bioimaging, biosensing, and cancer research, especially for photothermal and photodynamic therapy. The ease of functionalization with various ligands provides a novel approach to the precise delivery of these molecules to targeted areas. Gold NPs' ability to transfer heat and electricity positions them as valuable materials for advancing thermal management and electronic systems. Moreover, their inherent characteristics, such as inertness, give rise to the synthesis of novel antibacterial and antioxidant agents as they provide a biocompatible and low-toxicity approach. Chemical and physical synthesis methods are utilized to produce gold NPs. The pursuit of more ecologically sustainable and economically viable large-scale technologies, such as environmentally benign biological processes referred to as green/biological synthesis, has garnered increasing interest among global researchers. Green synthesis methods are more favorable than other synthesis techniques as they minimize the necessity for hazardous chemicals in the reduction process due to their simplicity, cost-effectiveness, energy efficiency, and biocompatibility. This article discusses the importance of gold NPs, their optical, conductivity, antibacterial, antioxidant, and anticancer properties, synthesis methods, contemporary uses, and biosafety, emphasizing the need to understand toxicology principles and green commercialization strategies.

Veterinary Drug Residues in Food Products of Animal Origin and Their Public Health Consequences: A Review

Veterinary medications used for disease treatment and prevention may remain in animal-origin foods, such as milk, eggs, honey and meat, which could pose a risk to the public's health. These drugs come from different groups of drugs, mostly with antibiotic, anti-parasitic or anti-inflammatory actions, in a range of food matrices including milk, meat or egg. This review is intended to provide the reader with a general insight about the current status of veterinary drug residues in food products of animal origin, detection methods and their public health consequences. The discovery of antimicrobials has led to the development of antibiotics for treating and preventing cattle illnesses and encouraging growth. However, the rise of drug resistance has led to increased antibiotic consumption and resistance among microbes in the animal habitat. This resistance can be passed to humans directly or indirectly through food consumption and direct or indirect interaction. Improper and illegal use, inadequate withdrawal periods and environmental contamination from veterinary drugs are reported to be the major causes for the formation of residue in food products of animal origin. The use of veterinary products above or below the advised level may also result in short- or long-term public health issues, such as the creation of resistant strains of micro-organisms, toxicity, allergy, mutagenesis, teratogenicity and carcinogenetic effects. To ensure consumer safety, veterinary drug residues in food must be under control.

Simultaneous detection of multiple mycotoxins in agricultural products: Recent advances in optical and electrochemical sensing methods

Mycotoxin contamination poses serious threats to human and animal health. Food and environmental systems are often simultaneously contaminated with multiple mycotoxins, a problem that is further exacerbated by the synergistic toxicological effects of these co-occurring mycotoxins. Consequently, the development of rapid detection methods capable of simultaneously identifying multiple mycotoxins in agricultural products is essential to prevent their entry into the food chain. Compared to standard detection methods, optical and electrochemical (EC) sensing methods have distinct advantages for the rapid detection of mycotoxins. This review comprehensively summarizes the latest advancements in the field of simultaneous detection of multiple mycotoxins using optical and EC sensing methods over the last 6 years (2018-2024). First, the review introduces the classification and relevant principles of optical and EC sensing methods. Thereafter, it emphasizes innovative simultaneous detection strategies within these approaches. Finally, it discusses current challenges and offers a reference for further research. Currently, the main challenge lies in the mutual interference among targets, making the development of an interference-free detection platform essential. Furthermore, the ongoing development of integrated technology is expected to aid regulatory authorities in improving the quality of agricultural products for field applications.

Microenvironment-responsive nanomedicines: a promising direction for tissue regeneration

Severe tissue defects present formidable challenges to human health, persisting as major contributors to mortality rates. The complex pathological microenvironment, particularly the disrupted immune landscape within these defects, poses substantial hurdles to existing tissue regeneration strategies. However, the emergence of nanobiotechnology has opened a new direction in immunomodulatory nanomedicine, providing encouraging prospects for tissue regeneration and restoration. This review aims to gather recent advances in immunomodulatory nanomedicine to foster tissue regeneration. We begin by elucidating the distinctive features of the local immune microenvironment within defective tissues and its crucial role in tissue regeneration. Subsequently, we explore the design and functional properties of immunomodulatory nanosystems. Finally, we address the challenges and prospects of clinical translation in nanomedicine development, aiming to propose a potent approach to enhance tissue regeneration through synergistic immune modulation and nanomedicine integration.

A sandwich-type electrochemical sensor based on RGO-CeO2-Au nanoparticles and double aptamers for ultrasensitive detection of glypican-3

A sandwich-type electrochemical aptasensor for ultrasensitive detection of glypican-3 (GPC3) was constructed using GPC3 aptamer (GPC3Apt) labelled reduced graphene oxide-cerium oxide-gold nanoparticles (RGO-CeO2-Au NPs) as the signal probe and the same GPC3Apt as the capture probe. The electrochemical redox properties of CeO2 (Ce3+/Ce4+) in the RGO-CeO2-Au NPs indicate the electrochemical signals. When the target GPC3 was present, an "aptamer-protein-aptamer" sandwich structure was formed on the sensing interface due to the specific binding between the protein and aptamers, resulting in an increased electrochemical redox signal detected by differential pulse voltammetry (DPV) technique. Under optimal conditions, the established aptasensor exhibited a logarithmic linear relationship between the current response and GPC3 concentration in the range 0.001-100.0 ng/mL, with a minimum detection limit of 0.74 pg/mL. Using the spike-recovery tests for measurement of the human serum samples, the recovery was from 99.26 to 114.01%, and the RSD range was 3.04 to 5.34%. Furthermore, the sandwich-type electrochemical aptasensor exhibited excellent performance characteristics such as good stability, high specificity, and high sensitivity, demonstrating effective detection of GPC3 in human serum samples and can be used as a clinical detection tool for GPC3.

Vertasile ferritin nanocages: Applications in detection and bioimaging

Food safety and human health remain significant concerns in the food industry. Detecting food contaminants and diagnosing diseases are critical aspects. Ferritin, an iron storage protein widely found in nature, offers unique advantages. Its hollow protein nanocage structure, distinct interfaces, hydrophobic or hydrophilic channels, and B-C loop regions recognized by transferrin receptor 1 make ferritin versatile for detecting heavy metals, free radicals, and bioimaging both in vitro and in vivo. This review summarizes ferritin's general characteristics, its specific properties as biosensors, and its applications in food safety and in vivo imaging. It emphasizes not only ferritin's role in detecting heavy metals like mercury and chemical hazards but also its potential in early diagnosing chronic diseases such as tumors, macrophages, and kidney diseases. Further research into ferritin promises advancements in enhancing food safety and improving human health diagnostics.

Surface-enhanced Raman scattering based on noble metal nanoassemblies for detecting harmful substances in food

Residues of harmful substances in food can severely damage human health. The content of these substances in food is generally low, making detection difficult. Surface-enhanced Raman scattering (SERS), based on noble metal nanomaterials, mainly gold (Au) and silver (Ag), has exhibited excellent capabilities for trace detection of various substances. Noble metal nanoassemblies, in particular, have extraordinary flexibility and tunable optical properties, which cannot be offered by single nanoparticles (NPs). These nanoassemblies, with their various morphologies synthesized using NPs through artificially induced self-assembly or template-driven preparation, can significantly enhance the local electric field and create "hot spots" due to the gaps between adjacent NPs. Consequently, the SERS properties of NPs become more prominent, leading to improved performance in the trace detection of various substances and detection limits that are considerably lower than the current relevant standards. Noble metal nanoassemblies show promising potential in ensuring food safety. This review discusses the synthesis methods and SERS properties of noble metal nanoassemblies and then concentrates on their application in detecting biotoxins, drug residues, illegal additives, and heavy metals. The study provides valuable references for further research into the application of nanoassemblies in food safety detection.

LAMP-CRISPR/Cas12a-based impedimetric biosensor powered by Fe3O4@Au-(S-polyA-S)-Au for detection of SARS-CoV-2

A low-cost, lab-made polytetrafluoroethylene micro-cell, equipped with three electrodes, wasd eveloped for the impedimetric detection of SARS-CoV-2. The gold working electrode was modified with a double-ended thiolated poly-adenine probe, which was conjugated with magnetic Fe₃O₄@Au nanoparticles (Fe3O4@Au-(S-polyA-S)-Au). After the loop-mediated isothermal amplification (LAMP) of viral RNA, the single-guide RNA (sgRNA), specifically bound to the SARS-CoV-2 target sequence, activates Cas12a. Cas12a then cleaved the immobilized probe. As a result, the magnetic Fe3O4@Au nanoparticles were released and adsorbed onto the gold electrode surface, using an external magnet. This process increased the physical surface area of the gold electrode, facilitating redox ion ([FeIII/II(CN)6]3-/4-) electron transfer. The decrease in the charge transfer resistance was utilized for SARS-CoV-2 detection. Our LAMP-CRISPR/Cas12a-based impedimetric biosensor, powered by Fe3O4@Au-(S-polyA-S)-Au, demonstrated impressive capabilities, including a remarkable detection limit of 0.8 aM (0.48 copies/µL) and a linear range of 0.01 to 36.06 fM.

A gold nanoparticle conjugated single-legged DNA walker driven by catalytic hairpin assembly biosensor to detect a prokaryotic pathogen

Catalytic hairpin assembly (CHA)-DNA walker allows nanostructures to spontaneously hybridize to the nucleic acids. The localized surface plasmon resonance provides the ability of color-shift for Au nanoparticles (AuNPs) to design a colorimetric biosensor by implementing CHA-DNA walker reaction on AuNPs. A target gene in Klebsiella pneumoniae as the reaction cascade trigger, was selected. H1 and H2 oligonucleotides as the components of the system were designed and verified by NUPACK. The AuNPs were conjugated to H1. The conjugation of the probes to the AuNPs was evaluated using FT-IR. The signal amplification process was conducted at 25℃. TEM imaging, zeta potential, spectroscopy, and gel-electrophoresis were used to examine the conduction of the reaction cascade and specificity. The sensitivity of the method was analyzed using serial dilution of the target. The formation of over-52 bp intermediate secondary structures (which only exist when the reaction happens) was confirmed by gel-electrophoresis. The color distinction between positive (0.08 to 0.058) and negative samples (0.098 to 0.05) was evidenced instantly and in a period of 90 min of the reaction as a drop change of 520 nm intensity absorbance. TEM imaging confirmed the further distance of AuNPs in the positive sample in comparison to that of the negative sample which reveals effective detection of the pathogen. The LOD of the technique was measured as 2.5 nM of the target sequence. The diagnostic approach is a label-free, enzyme-independent approach and can be executed in a single step. It has been designed by employing the CHA-DNA walker system along with the colorimetric properties of AuNPs for the first time, thereby paving the way for more rapid and accurate diagnostic kits.

Real-Time Monitoring of Molecules in Aqueous Solution via a Surface-Functionalized Ag-Anodic Aluminum Oxide Surface-Enhanced Raman Scattering Platform

Real-time monitoring of molecular species in aqueous solutions is crucial for diverse scientific applications, from biomedical diagnostics to environmental analysis. In this study, we investigate the selective detection and discrimination of specific molecules in aqueous solution samples using a Ag-coated anodized aluminum oxide (Ag-AAO) surface functionalized with thiol molecules. Our investigation harnesses the power of surface-enhanced Raman scattering (SERS) synergized with principal component analysis (PCA) to elucidate the distinctive signatures of aqueous dopamine and l-tyrosine molecules. By scrutinizing the Raman spectra of surface-treated molecules, we unveil nuanced variations driven by the unique functional groups of the thiol molecules and their dynamic interactions with the target molecules in solution. Notably, we observe different alterations in the SERS spectra of Ag-AAO surface-functionalized boronic acid molecules for detection of dopamine and l-tyrosine, even at a concentration as low as 10-8 M. Moreover, the spectral PCA elucidates the discrimination of dopamine and l-tyrosine within the aqueous environment attributed to the different molecular interactions near SERS-active hotspots. Our findings facilitate real-time monitoring of minute analytes with exceptional molecular selectivity, ushering in an era of precise chemical analysis in aqueous solutions.

Detection of foodborne pathogens in contaminated food using nanomaterial-based electrochemical biosensors

Foodborne pathogens are a grave concern for the for food, medical, environmental, and economic sectors. Their ease of transmission and resistance to treatments, such as antimicrobial agents, make them an important challenge. Food tainted with these pathogens is swiftly rejected, and if ingested, can result in severe illnesses and even fatalities. This review provides and overview of the current status of various pathogens and their metabolites transmitted through food. Despite a plethora of studies on treatments to eradicate and inhibit these pathogens, their indiscriminate use can compromise the sensory properties of food and lead to contamination. Therefore, the study of detection methods such as electrochemical biosensors has been proposed, which are devices with advantages such as simplicity, fast response, and sensitivity. However, these biosensors may also present some limitations. In this regard, it has been reported that nanomaterials with high conductivity, surface-to-volume ratio, and robustness have been observed to improve the detection of foodborne pathogens or their metabolites. Therefore, in this work, we analyze the detection of pathogens transmitted through food and their metabolites using electrochemical biosensors based on nanomaterials.

Precise pathogen quantification by CRISPR-Cas: a sweet but tough nut to crack

Pathogen detection is increasingly applied in medical diagnosis, food processing and safety, and environmental monitoring. Rapid, sensitive, and accurate pathogen quantification is the most critical prerequisite for assessing protocols and preventing risks. Among various methods evolved, those based on clustered regularly interspaced short palindromic repeats (CRISPR)-associated proteins (Cas) have been developed as important pathogen detection strategies due to their distinct advantages of rapid target recognition, programmability, ultra-specificity, and potential for scalability of point-of-care testing (POCT). However, arguments and concerns on the quantitative capability of CRISPR-based strategies are ongoing. Herein, we systematically overview CRISPR-based pathogen quantification strategies according to the principles, properties, and application scenarios. Notably, we review future challenges and perspectives to address the of precise pathogen quantification by CRISPR-Cas. We hope the insights presented in this review will benefit development of CRISPR-based pathogen detection methods.