Detection of antibiotics in food: New achievements in the development of biosensors

Electrochemical β-lactamase immunostrip sensor with 3D hydrogel-paper scaffold for rapid detection & post-antibiotic therapy monitoring in drug-resistant bloodstream infections

BACKGROUND

The increasing prevalence of drug-resistant bacterial bloodstream infections, particularly those caused by Methicillin-resistant Staphylococcus aureus (MRSA), presents a critical global healthcare challenge. Current diagnostic methods often lack the speed and sensitivity necessary for timely antibiotic interventions, leading to poor patient outcomes and increased resistance due to misuse of broad-spectrum antibiotics. Existing platforms rarely combine rapid detection, low detection limits, and real-time therapy monitoring, leaving a crucial gap in effective infection management.

RESULTS

This study introduces an electrochemical immunostrip sensor for the rapid detection of β-lactamase (BL), an enzyme associated with drug resistance. Using a novel 3D hydrogel-paper scaffold, the sensor achieves a detection limit of 0.146 mU/ml and accurately detects BL-producing pathogens, including MRSA, from clinical samples with bacterial loads as low as 102 CFU/ml. The platform provides post culture detection results within 1 h, post antibiotic therapy monitoring within 4 h and demonstrates high specificity (∼100 %) by differentiating BL-producing strains from non-producing isolates.

SIGNIFICANCE AND NOVELTY

This study introduces a new electrochemical smart immunostrip sensor integrated with a 3D hydrogel-paper scaffold for β-lactamase detection, which offers high sensitivity and specificity. Unlike conventional diagnostics, it enables user-friendly, rapid, cost-effective detection within 1 h post-blood culture and real-time antibiotic therapy monitoring in just 4 h, transforming clinically actionable point-of-care (POC) management of drug-resistant bloodstream infections.

Detection of antibiotic sulfamethoxazole residues in milk using a molecularly imprinted polymer-based thermal biosensor

Antibiotic resistance is a growing concern, partly due to inadequate inspections in the food safety chain. The accumulation of antibiotics like sulfamethoxazole (SMX) in animal products contributes to the rise of resistant microorganisms, posing a global health challenge. This work focuses on developing a thermal sensor to quickly and affordably detect SMX residues in milk samples. Molecularly imprinted polymers (MIPs) were synthesized and immobilized on an aluminum chip to measure thermal changes using the heat-transfer method (HTM). The sensor's detection limit in calcium chloride solutions was 261 ± 12 pmol L-1, well below regulatory limits for sulfonamides in dairy. The sensor also showed good selectivity when tested against antibiotics from different classes, and good performances in spiked milk samples. These results indicate that the thermal sensor provides a sensitive, low-cost alternative for detecting sulfamethoxazole traces in dairy products, contributing to improved food safety.

Synthesis of polyadenine-aptamer-stabilized gold nanoclusters and application to the detection of tobramycin in real samples based on their peroxidase-like activity

Tobramycin (TOB) is a widely used aminoglycoside antibiotic for treating human and animal diseases. However, its overuse poses a threat to human health, necessitating the development of a rapid and simple detection method. In this study, polyadenine-aptamer-stabilized gold nanoclusters (Ax-Apt-AuNCs) were synthesized, to investigate the impact of different polyadenine lengths on their properties. A20-Apt-AuNCs demonstrated efficient catalytic activity in the oxidation of o-phenylenediamine to 2,3-diaminophenazine (DAP) in the presence of hydrogen peroxide, resulting in yellow fluorescence emission. Upon binding specifically to the TOB aptamer on A20-Apt-AuNCs, TOB enhanced both their peroxidase-like activity and the fluorescence intensity of DAP. Based on this mechanism, a fluorescence-enhanced aptasensor was developed for TOB detection. The aptasensor exhibited a linear detection range of 10.0 nM to 1.0 μM, with a detection limit of 2.63 nM. Furthermore, its application in real sample analysis produced satisfactory results.

Chemically reduced graphene oxide based assembly of Aptasensor for sensitive and probe-free detection of penicillin-G

The widespread use of antibiotics in livestock and poultry leads to antibiotic residues in food, posing public health risks. To ensure food safety, monitoring antibiotic levels in dairy and poultry is essential, especially for Penicillin-G (Pen-G), a frequently used β-lactam antibiotic. This study presents an electrochemical aptasensor for detecting Pen-G in food samples, using chemically reduced graphene oxide (crGO) conjugated with Pen-G-specific aptamer on electrode. The sensors construction was validated via various microscopy and spectroscopy techniques and its performance optimized by adjusting factors such as pH, scan rate, temperature, concentration of aptamer, and reaction time using differential pulse voltammetry (DPV) and cyclic voltammetry (CV). It achieved a detection limit of 1.24 pM, effectively distinguishing Pen-G from other antibiotics in real milk, meat, and egg samples, with stability for up to 3 weeks, making it a valuable tool for antibiotic monitoring in food products.

Tailored Fluorescent Metal-Organic Frameworks Hybrid Membrane Sensor Arrays: Simultaneous and Selective Quantification of Multiple Antibiotics

Sensor array offers significant potential for rapid, high-throughput antibiotic detection. However, cross-reactivity-based sensor arrays often lack accuracy, despite comprehensive data analysis; while traditional high-affinity-based sensors based on antibodies/aptamers frequently suffer from complicated design and poor robustness. Here, a filterable paper-based fluorescent metal-organic frameworks (MOFs) sensor array is developed for one-to-one recognition and quantification of multiple antibiotics. Three representative MOFs are designed to exceptional affinity and specificity for the target antibiotic. A filtration-assisted detection enhances sensitivity, achieving parts-per-billion (ppb)-level detection in mixed solutions. The proposed approach integrates recognition and signal generation, streamlined 10-min process. The robustness of the MOFs also enables direct detection in raw samples containing organic solvents, which is not achievable by conventional methods. Notably, the sensor array can be easily incorporated into a smartphone-based portable device, coupled with a user-friendly image analysis applet for one-step extraction and quantitative detection in chicken samples. Leveraging MOFs' versatility, this method can be extended to simultaneously detect a broad range of antibiotics, offering the potential for universal, high-throughput accurate detection of various chemical targets.

Recent advances and challenges in graphene-based electrochemical biosensors for food safety

Ensuring food safety is a critical global concern, particularly in light of recent pandemics and rising contamination risks from pesticides, antibiotics, toxins, and allergens. These contaminants pose significant health hazards, including neurological disorders, endocrine disruption, antibiotic resistance, and carcinogenic effects. Regulatory agencies such as the Food and Agriculture Organization (FAO), the World Health Organization (WHO), and the United States Food and Drug Administration (FDA) have established strict maximum residue limits (MRLs) to mitigate these risks. However, enforcement remains challenging due to limitations in current detection methods. The increasing global population and limited food resources have exacerbated food security challenges, while contaminants can infiltrate food at various stages, including production, processing, and packaging. Despite consumer awareness, significant amounts of food are discarded due to quality concerns. To address these issues, researchers are actively developing low-cost, reliable sensing technologies for real-time food quality assessment and contamination detection. Among these, graphene-based electrochemical biosensors have emerged as a promising solution due to their high sensitivity, selectivity, and cost-effectiveness. This review provides an in-depth analysis of recent advancements in graphene-based electrochemical biosensors, focusing on their role in detecting foodborne hazards and improving food quality monitoring. By integrating selective layers, these sensors enhance detection efficiency and provide an innovative solution for safeguarding public health. The findings underscore the transformative potential of graphene-derived biosensors in food safety diagnostics, paving the way for more reliable and sustainable food monitoring systems.

Preparation of CHS-Fe3O4@@ZIF-8 peroxidase-mimic with an ultra-thin hollow layer for ultrasensitive electrochemical detection of kanamycin

A highly sensitive and selective electrochemical biosensor was developed for the detection of kanamycin using a core-hollow-shell structured peroxidase-mimic nanozyme, CHS-Fe₃O₄@@ZIF-8. The synthesized CHS-Fe3O4@@ZIF-8 was characterized with scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. It was found that the CHS-Fe3O4@@ZIF-8 exhibits excellent peroxidase-like activity due to  its ultra-thin hollow layer. Besides, CHS-Fe3O4@@ZIF-8 functionalized with complementary chains of kanamycin aptamer was anchored to the electrode surface via complementary base pairing with the kanamycin aptamer. Upon the presence of kanamycin, a strand displacement reaction was triggered leading to a reduction in the number of the CHS-Fe3O4@@ZIF-8, which slowed down the catalytic reaction of the substrate 3,3',5,5' -tetramethylbenzidine (TMB) facilitated by CHS-Fe3O4@@ZIF 8. Differential pulse voltammetry (DPV) was employed to measure and record changes in peak current resulting from catalytic oxidation product formation (oxidation product of TMB). The electrochemical signal exhibited a linear relationship with logarithmic variations in kanamycin concentration within a range spanning from 10 to 8000 pM and achieved an impressive detection limit as low as 7.52 pM. Furthermore, successful detection of kanamycin content in serum samples using this sensor demonstrated its good specificity and reproducibility. These findings indicate that the constructed electrochemical kanamycin sensor holds significant potential for practical applications. The biosensor demonstrated high selectivity, distinguishing kanamycin from other antibiotics, and exhibited good reproducibility, making it reliable for practical applications. The successful detection of kanamycin in serum samples further underscores the sensor's potential for real-world applications, particularly in monitoring antibiotic residues in food products and clinical diagnostics.

Recent advances in electrochemical sensing and remediation technologies for ciprofloxacin

Ciprofloxacin (CIP) is an extensively used broad-spectrum, fluoroquinolone antibiotic used for treating diverse bacterial infections. Effluent treatment plants (ETPs) worldwide lack technologies to detect or remediate antibiotics. CIP reaches the aquatic phase primarily due to inappropriate disposal practices, lack of point-of-use sensing, and preloaded activated charcoal filter at ETPs. The co-existence of bacteria and CIP in such aqueous pools has promoted fluoroquinolone resistance in bacteria and should be minimized. The worldwide accepted standard detection methodologies for the detection of CIP are high-performance liquid chromatography and mass spectrometry, which are lab-based, require state-of-the-art equipment, and are expensive. Hence, it is difficult to integrate them for on-site monitoring. Further, the current remediation technologies like conventional sludge-treatment techniques fail to remove antibiotics such as CIP. Several point-of-use technologies for the detection of CIP are being investigated. These typically involve the development of electrochemical sensors where substrates, modifiers, biorecognition elements, and their chemistries are designed and optimized to enable robust, point-of-use detection of CIP. Similarly, remediation techniques like adsorption, membrane filtration, ion exchange, photocatalysis, ozonation, oxidation by Fenton's reagent, and bioremediation are explored, but their onsite use is limited. The use of these sensing and remediation technologies in tandem is possibly the only way the issues related to antimicrobial resistance may be effectively tackled. This article provides a focused critical review on the recent advances in the development of such technologies, laying out the prospects and perspectives of their synergistic use to curb the menace of AMR and preserve antibiotics.

Progress of machine learning-based biosensors for the monitoring of food safety: A review

Rapid urbanization and growing food demand caused people to be concerned about food safety. Biosensors have gained considerable attention for assessing food safety due to selectivity, and sensitivity but poor stability inherently limits their application. The emergence of machine learning (ML) has enhanced the efficiency of different sensors for food safety assessment. The ML combined with various noninvasive biosensors has been implemented efficiently to monitor food safety by considering the stability of bio-recognition molecules. This review comprehensively summarizes the application of ML-powered biosensors to investigate food safety. Initially, different detector-based biosensors using biological molecules with their advantages and disadvantages and biosensor-related various ML algorithms for food safety monitoring have been discussed. Next, the application of ML-powered biosensors to detect antibiotics, foodborne microorganisms, mycotoxins, pesticides, heavy metals, anions, and persistent organic pollutants has been highlighted for the last five years. The challenges and prospects have also been deliberated. This review provides a new prospect in developing various biosensors for multi-food contaminants powered by suitable ML algorithms to monitor in-situ food safety.

Molecular imprinting technology for electrochemical sensing of kasugamycin in food products based on Cu2+/Cu+ stripping current

An electrochemical sensing approach was developed for the detection of the agricultural antibiotic drug kasugamycin. The method involves the construction of an electrochemical sensor comprising molecularly imprinted polymers (MIPs) embedded within a carbon paste (CP) matrix. The MIPs are designed to have imprinted sites that match the size and geometry of the Cu(II)-kasugamycin coordinated complex. Upon removal of kasugamycin, cavities suitable for the drug's entrance are formed within the MIPs. The presence of Cu(II) facilitates the detection of the drug by generating a redox signal of Cu(II)-Cu(I), which can be easily detected using differential pulse voltammetry (DPV). The signal response of Cu(II)-Cu(I) increases in the presence of the drug, promoting the accumulation of Cu(II) ions within the imprinted cavities. Under optimized conditions, the anodic peak (Ipa) signal of Cu(II)-Cu(I) exhibits an increase proportional to the concentration of kasugamycin within the range of 0.15-140 μM. The detection limit (LOD, S/N = 3) achieved is 0.046 μM. The proposed sensor demonstrates several characteristic features including good stability, reliable performance, a low detection limit, and excellent selectivity. The Cu(II)-MIP@CP sensor proved effective in detecting kasugamycin within complex samples like meat, milk, and cucumber, yielding recovery% ranging from 96.0 to 103.8%. Additionally, the relative standard deviation % (RSD%) fell within the range of 2.2% to 4.0%, indicating good precision and reliability.

Engineering with Biomedical Sciences Changing the Horizon of Healthcare-A Review

In the dynamic realm of healthcare, the convergence of engineering and biomedical sciences has emerged as a pivotal frontier. In this review we go into specific areas of innovation, including medical imaging and diagnosis, developments in biomedical sensors, and drug delivery systems. Wearable biosensors, non-wearable biosensors, and biochips, which include gene chips, protein chips, and cell chips, are all included in the scope of the topic that pertains to biomedical sensors. Extensive research is conducted on drug delivery systems, spanning topics such as the integration of computer modeling, the optimization of drug formulations, and the design of delivery devices. Furthermore, the paper investigates intelligent drug delivery methods, which encompass stimuli-responsive systems such as temperature, redox, pH, light, enzyme, and magnetic responsive systems. In addition to that, the review goes into topics such as tissue engineering, regenerative medicine, biomedical robotics, automation, biomechanics, and the utilization of green biomaterials. The purpose of this analysis is to provide insights that will enhance continuing research and development efforts in engineering-driven biomedical breakthroughs, ultimately contributing to the improvement of healthcare. These insights will be provided by addressing difficulties and highlighting future prospects.

Biosensor in smart food traceability system for food safety and security

The burden of food contamination and food wastage has significantly contributed to the increased prevalence of foodborne disease and food insecurity all over the world. Due to this, there is an urgent need to develop a smarter food traceability system. Recent advancements in biosensors that are easy-to-use, rapid yet selective, sensitive, and cost-effective have shown great promise to meet the critical demand for onsite and immediate diagnosis and treatment of food safety and quality control (i.e. point-of-care technology). This review article focuses on the recent development of different biosensors for food safety and quality monitoring. In general, the application of biosensors in agriculture (i.e. pre-harvest stage) for early detection and routine control of plant infections or stress is discussed. Afterward, a more detailed advancement of biosensors in the past five years within the food supply chain (i.e. post-harvest stage) to detect different types of food contaminants and smart food packaging is highlighted. A section that discusses perspectives for the development of biosensors in the future is also mentioned.

Antibiotic Residues in Raw Cow's Milk: A Systematic Review of the Last Decade

The inappropriate use of antimicrobials in dairy animals can lead to residues in raw milk and in dairy products. Foods containing residues of this nature, whether in the short, medium, or long term, cause serious health harm. Absence of these compounds in foods should be a premise for declaring safety. This systematic review aimed to identify the antibiotic residues most frequently found in raw bovine milk and the methodologies used to detect such residues over the ten years from 2013 to 2023. PRISMA guidelines for systematic reviews were followed, by searching the Web of Science, PubMed Central, Scopus, and Springer databases. The search strategy identified 248 articles, and after applying the selection and quality assessment criteria, 16 studies were selected. The number of samples analyzed was 411,530, of which 0.21% tested positive for some type of antibiotic. Eight classes and 38 different types of antibiotics were identified. The most common class was tetracycline, with emphasis on sulfonamides and quinolones, which have shown increasing prevalence among residues in milk in recent years. A total of 56.25% of the studies employed rapid kits to detect residues, 18.75% chromatography, and 25% both techniques. Antibiotic residues in bovine raw milk should be a great concern for animal, environmental, and human health.

The Global Rise of ESBL-Producing Escherichia coli in the Livestock Sector: A Five-Year Overview

β-lactam antibiotics are a key element in the treatment of bacterial infections. However, the excessive use of these antibiotics has contributed to the emergence of β-lactam-resistant enterobacteria, including Escherichia coli. One of the main challenges facing the public health sector is antibacterial resistance (ABR), mainly due to limited options in its pharmacological treatment. Currently, extended-spectrum β-lactamases (ESBLs) present an alarming situation, as there is an increase in morbidity and mortality rates, prolonged hospital stays, and increased costs for sanitary supplies, which involve not only humans but also the environment and animals, especially animals destined for food production. This review presents an analysis of the prevalence of ESBL-producing E. coli and its distribution in different animal sources throughout the world, providing an understanding of the association with resistance and virulence genes, as well as perceiving the population structure of E. coli.

ε-Poly-l-lysine: A Naturally Occurring Biodegradable Polypeptide for Selective Detection of 5-Nitroimidazole Antibiotics in Animal Products and Living Cells via Fluorescence

The 5-nitroimidazole (5-NI) class of antibiotics, such as metronidazole, ornidazole, secnidazole, and tinidazole, are widely used to prevent bacterial infection in humans and livestock industries. However, their overuse contaminates the farmed animal products and water bodies. Hence, a selective, sensitive, and cost-effective method to detect 5-NI antibiotics is the need of the hour. Herein, we report a rapid, inexpensive, and efficient sensing system to detect 5-NI drugs using an as-prepared solution of ε-poly-l-lysine (ε-PL), a naturally occurring and biodegradable homopolypeptide that has an intrinsic fluorescence via clustering-triggered emission. The low nanomolar detection limit (3.25-3.97 nM) for the aforementioned representative 5-NI drugs highlights the sensitivity of the system, outperforming most of the reported sensors alike. The resulting fluorescence quenching was found to be static in nature. Importantly, excellent recovery (100.26-104.41%) was obtained for all real samples and animal products tested. Visual detection was demonstrated by using paper strips and silica gel for practical applications. Furthermore, ε-PL could detect 5-NI antibiotics in living 3T3-L1 mouse fibroblast cells via cellular imaging. Taken together, the present work demonstrates the detection of 5-NI antibiotics using a biocompatible natural polypeptide, ε-PL, and represents a simple and inexpensive analytical tool for practical application.

Development of transcriptional factor-based whole-cell biosensors to monitor and degrade antibiotics using mutant cells obtained via adaptive laboratory evolution

With the widespread use of antibiotics and increasing environmental concerns regarding antibiotic abuse, the detection and degradation of antibiotic residues in various samples has become a pressing issue. Transcriptional factor (TF)-based whole-cell biosensors are low-cost, easy-to-use, and flexible tools for detecting chemicals and controlling bioprocesses. However, because of cytotoxicity caused by antibiotics, the application of such biosensors is limited in the presence of antibiotics. In this study, we used antibiotic-tolerant mutants obtained via adaptive laboratory evolution (ALE) to develop TF-based whole-cell biosensors for antibiotic monitoring and degradation. The biosensors had high performance and stability in detecting relatively high concentrations of tetracycline (Tc) and nisin. The ALE mutant-based Tc biosensor exhibited a 10-fold larger linear detection range than the wild-type strain-based biosensor. Then, the Tc biosensor was employed to detect residual amounts of Tc in mouse stool, serum, and urine samples and facilitate Tc biodegradation in mouse stool, demonstrating its high utility. Considering that ALE has been demonstrated to enhance cell tolerance to various toxic chemicals, our strategy might facilitate the development of whole-cell biosensors for most antibiotics and other toxic ligands.

A novel electrochemical sensor for the detection of metronidazole residues in food samples

The widespread use and misuse of antibiotics in pharmaceuticals and animal farming has resulted in their accumulation in food sources and the environment, posing significant threats to human health, the environment, and the global economy. In this study, we have developed a hypersensitive, and ultra-selective electrochemical sensor, the first of its kind, by integrating a thermally annealed gold-silver alloy nanoporous matrix (TA-Au-Ag-ANpM) with reduced graphene oxide (r-GO) and poly(glycine) at the surface of a glassy carbon electrode (GCE). This sensor aims to detect life-threatening metronidazole (MTZ) residues in food samples. TA-Au-Ag-ANpM/r-GO/poly(glycine)/GCE was thoroughly characterized using a range of analytical techniques, including UV-Vis, FT-IR, XRD, SEM, and EDX. Furthermore, its electrochemical properties were investigated by cyclic voltammetry (CV), square wave voltammetry (SWV), and electrochemical impedance spectroscopy (EIS). The sensor exhibited outstanding performance, with a broad linear range of 2.0 pM-410 μM. The limits of detection (LOD) and quantification (LOQ) were determined to be 0.0312 pM and 0.104 pM, respectively. The TA-Au-Ag-ANpM/r-GO/poly(glycine)/GCE exhibited exceptional reproducibility, repeatability, stability, and resistance to interferences. Moreover, the sensor demonstrated outstanding performance in detecting MTZ residues in milk powder, pork, and chicken meat samples, achieving very good recoveries (96.9%-101.4%) with a relative standard deviation (RSD) below 5%. This performance highlights the potential for practical applications in food safety and quality monitoring. Therefore, the developed sensor contributes to the advancement of electrochemical sensing technology and its application in ensuring food safety and integrity by combating antibiotic residues.

Microbial Degradation of Tetracycline Antibiotics: Mechanisms and Environmental Implications

The escalating global consumption of tetracyclines (TCs) as broad-spectrum antibiotics necessitates innovative approaches to mitigate their pervasive environmental persistence and associated risks. While initiatives such as China's antimicrobial reduction efforts highlight the urgency of responsible TC usage, the need for efficient degradation methods remains paramount. Microbial degradation emerges as a promising solution, offering novel insights into degradation pathways and mechanisms. Despite challenges, including the optimization of microbial activity conditions and the risk of antibiotic resistance development, microbial degradation showcases significant innovation in its cost-effectiveness, environmental friendliness, and simplicity of implementation compared to traditional degradation methods. While the published reviews have summarized some aspects of biodegradation of TCs, a systematic and comprehensive summary of all the TC biodegradation pathways, reactions, intermediates, and final products including ring-opening products involved with enzymes and mechanisms of each bacterium and fungus reported is necessary. This review aims to fill the current gap in the literature by offering a thorough and systematic overview of the structure, bioactivity mechanism, detection methods, microbial degradation pathways, and molecular mechanisms of all tetracycline antibiotics in various microorganisms. It comprehensively collects and analyzes data on the microbial degradation pathways, including bacteria and fungi, intermediate and final products, ring-opening products, product toxicity, and the degradation mechanisms for all tetracyclines. Additionally, it points out future directions for the discovery of degradation-related genes/enzymes and microbial resources that can effectively degrade tetracyclines. This review is expected to contribute to advancing knowledge in this field and promoting the development of sustainable remediation strategies for contaminated environments.

Multilayered Fe3O4@(ZIF-8)3 combined with a computer-vision-enhanced immunosensor for chloramphenicol enrichment and detection

The misuse and overuse of chloramphenicol poses severe threats to food safety and human health. In this work, we developed a magnetic solid-phase extraction (MSPE) pretreatment material coated with a multilayered metal-organic framework (MOF), Fe3O4 @ (ZIF-8)3, for the separation and enrichment of chloramphenicol from fish. Furthermore, we designed an artificial-intelligence-enhanced single microsphere immunosensor. The inherent ultra-high porosity of the MOF and the multilayer assembly strategy allowed for efficient chloramphenicol enrichment (4.51 mg/g within 20 min). Notably, Fe3O4 @ (ZIF-8)3 exhibits a 39.20% increase in adsorption capacity compared to Fe3O4 @ZIF-8. Leveraging the remarkable decoding abilities of artificial intelligence, we achieved the highly sensitive detection of chloramphenicol using a straightforward procedure without the need for specialized equipment, obtaining a notably low detection limit of 46.42 pM. Furthermore, the assay was successfully employed to detect chloramphenicol in fish samples with high accuracy. The developed immunosensor offers a robust point-of-care testing tool for safeguarding food safety and public health.

Microfabrication of engineered Lactococcus lactis biocarriers with genetically programmed immunorecognition probes for sensitive lateral flow immunoassay of antibiotic in milk and lake water

Micro/nanomaterials display considerable potential for increasing the sensitivity of lateral flow immunoassay (LFIA) by acting as 3D carriers for both antibodies and signals. The key to achieving high detection sensitivity depends on the probe's orientation on the material surface and its multivalent biomolecular interactions with targets. Here, we engineer Lactococcus lactis as the bacterial microcarrier (BMC) for a multivalent immunorecognition probe that was genetically programmed to display multifunctional components including a phage-screened single-chain variable fragment (scFv), an enhanced green fluorescent protein (eGFP), and a C-terminal peptidoglycan-binding domain (AcmA) anchored on BMC through the cell wall peptidoglycan. The innovative design of this biocarrier system, which incorporates a lab-on-a-chip microfluidic device, allows for the rapid and non-destructive self-assembly of the multivalent scFv-eGFP-AcmA@BMC probe, in which the 3D structure of BMC with a large peptidoglycan surface area facilitates the precisely orientated attachment and immobilization of scFv-eGFP-AcmA. This leads to a remarkable fluorescence aggregation amplification effect in LFIA, outperforming a monovalent 2D scFv-eGFP-AcmA probe for florfenicol detection. By designing a portable sensing device, we achieved an exceptionally low detection limit of 0.28 pg/mL and 0.21 pg/mL for florfenicol in lake water and milk sample, respectively. The successful microfabrication of this biocarrier holds potential to inspire innovative biohybrid designs for environment and food safety biosensing applications.

Blue-emitting tryptophan-protected gold nanoclusters acted as a sensitive nanosensor for fluorescence sensing and visual imaging detection of furaltadone

Herein, blue-emitting gold nanoclusters (Au NCs) were carried out through tryptophan as the protecting and reducing agents. In aqueous solution of Au NCs@tryptophan, the addition of furaltadone guaranteed the interaction of furaltadone with tryptophan around Au NCs. The propinquity of furaltadone to Au NCs caused that the fluorescence of Au NCs was weakened by furaltadone based on the inner filter effect (IFE). Under the optimal measurement conditions, the logarithm of relative fluorescence intensity of Au NCs@tryptophan was linearly carried out with the furaltadone amount increasing from 0.5 to 100 μM, the corresponding detection limit was 0.087 μM. The fluorescence change of Au NCs@tryptophan displayed excellent selectivity and sensitivity for furaltadone than other possible substance in the human body. In view of Au NCs@tryptophan, the as-performed fluorescence nanosensor suggested outstanding ability for furaltadone sensing in real samples. Obviously, this nanoprobe of furaltadone could implement the naked-eye visual fluorescence determination of furaltadone.

Electrospun nanofiber-based sensors for the detection of chemical and biological contaminants/hazards in the food industries

Food contamination reveals a major health risk globally and presents a significant challenge for the food industry. It can stem from biological contaminants like pathogens, parasites, and viruses, or chemical contaminants such as heavy metals, pesticides, drugs, and hormones. There is also the possibility of naturally occurring hazardous chemicals. Consequently, the development of sensing platforms has become crucial to accurately and rapidly identify contaminants and hazards in food products. Electrospun nanofibers (NFs) offer a promising solution due to their unique three-dimensional architecture, large specific surface area, and ease of preparation. Moreover, NFs exhibit excellent biocompatibility, degradability, and adaptability, making monitoring more convenient and environmentally friendly. These characteristics also significantly reduce the detection process of contaminants. NF-based sensors have the ability to detect a wide range of biological, chemicals, and physical hazards. Recent research on NFs-based sensors for the detection of various food contaminants/hazards, such as pathogens, pesticide/drugs residues, toxins, allergens, and heavy metals, is presented in this review.

Ultrasensitive and selective detection of sulfamethazine in milk via a Janus-labeled Au nanoparticle-based surface-enhanced Raman scattering-immunochromatographic assay

Sulfamethazine (SM2) is an antibacterial drug，which has been extensively used in human and veterinary medicine, long-term consumption of which may lead to the accumulation of sulfonamides in the body. Detection of sulfonamides often uses microbiological approaches, mass spectrometry and chromatography, which are expensive and time-consuming. Surface-enhanced Raman scattering-based immunochromatographic assay (SERS-ICA) has been recently applied in the detection. Herein, a Janus-labeled Au nanoparticle with subnanosized SiO2-monoclonal antibody and SERS reporter (DTNB) modified simultaneously (mAbAuNpDTNB) has been developed in a SERS-based lateral flow immunosensor, which can be used for rapid, quantitative and ultrasensitive detection of sulfamethazine residue in milk. The mAbAuNpDTNB exhibits a specific array on a paper stripe, which not only identifies sulfamethazine but also straightforwardly exposes the Raman reporter between the AuNps via self-assembly. The detection sensitivity of SERS-ICA for sulfamethazine reached 0.1 pg/mL, which was far below the previously published value by ELISA and the maximum residue limit set by the European Union. The entire SERS-ICA detection for sulfamethazine was completed within 15 min. Furthermore, high accuracy for this assay was exhibited in the spiking experiment with a recovery percentage of 88.1%-112.7%. The results demonstrated that this SERS-ICA can potentially be applied in point-of-care testing as an ultrasensitive and quantitative to semi-quantitative analytical method.

Functionalities of electrochemical fluoroquinolone sensors and biosensors

Fluoroquinolones (FQs) are a class of broad-spectrum antimicrobial agents that are used to treat variety of infectious diseases. This class of antibiotics was being used for patients exhibiting early symptoms of a human respiratory disease known as the COVID-19 virus. As a result, this outbreak causes an increase in drug-resistant strains and environmental pollution, both of which pose serious threats to biota and human health. Thus, to ensure public health and prevent antimicrobial resistance, it is crucial to develop effective detection methods for FQs determination in water bodies even at trace levels. Due to their characteristics like specificity, selectivity, sensitivity, and low detection limits, electrochemical biosensors are promising future platforms for quick and on-site monitoring of FQs residues in a variety of samples when compared to conventional detection techniques. Despite their excellent properties, biosensor stability continues to be a problem even today. However, the integration of nanomaterials (NMs) could improve biocompatibility, stability, sensitivity, and speed of response in biosensors. This review concentrated on recent developments and contemporary methods in FQs biosensors. Furthermore, a variety of modification materials on the electrode surface are discussed. We also pay more attention to the practical applications of electrochemical biosensors for FQs detection. In addition, the existing challenges, outlook, and promising future perspectives in this field have been proposed. We hope that this review can serve as a bedrock for future researchers and provide new ideas for the development of electrochemical biosensors for antibiotics detection in the future.

Rhodamine derivative-functionalized mesoporous silica-Al3+ hybrid material for fluorescence "turn-on" detection of tetracycline antibiotics in aqueous media

The organic-inorganic hybrid material was prepared by embedding 2-amino-3',6'-bis(diethylamino)spiro[isoindoline-1,9'-xanthen]-3-one (RBH) onto mesoporous SBA-15 silica and coordinating it with Al3+ (RBH-SBA-15-Al3+). RBH-SBA-15-Al3+ was used for the selective and sensitive detection of tetracycline antibiotics (TAs) in aqueous media based on the binding site-signaling unit mechanism, in which Al3+ acted as the binding site and the fluorescence intensity at 586 nm as the response signal. The addition of TAs to RBH-SBA-15-Al3+ suspensions resulted in the formation of RBH-SBA-15-Al3+-TAs conjugates, which realized the electron transfer process and turned-on fluorescence signal at 586 nm. The detection limits for tetracycline (TC), oxytetracycline, and chlortetracycline were 0.06, 0.06, and 0.03 µM, respectively. Meanwhile, the detection of TC was feasible in real samples, such as tap water and honey. In addition, RBH-SBA-15 can operate as a TRANSFER logic gate by using Al3+ and TAs as input signals and the fluorescence intensity at 586 nm as output signal. This study proposes an efficient strategy for the selective detection of target analytes by introducing interaction sites (e.g. Al3+) with target analytes in the system.

Surface plasmonic biosensors: principles, designs and applications

Recently, surface plasmon resonance (SPR) biosensors have been widely used in environmental monitoring, food contamination detection and diagnosing medical conditions due to their superior sensitivity, label-free detection and rapid analysis speed. This paper briefly elaborates on the development history of SPR technology and introduces SPR signal sensing principles. A summary of recent applications of SPR sensors in different fields is highlighted, including their figures of merit and limitations. Finally, the personal perspectives and future development trends about sensor preparation and design are discussed in detail, which may be critical for improving the performance of SPR sensors.

Immobilization of Enzyme Electrochemical Biosensors and Their Application to Food Bioprocess Monitoring

Electrochemical biosensors based on immobilized enzymes are among the most popular and commercially successful biosensors. The literature in this field suggests that modification of electrodes with nanomaterials is an excellent method for enzyme immobilization, which can greatly improve the stability and sensitivity of the sensor. However, the poor stability, weak reproducibility, and limited lifetime of the enzyme itself still limit the requirements for the development of enzyme electrochemical biosensors for food production process monitoring. Therefore, constructing sensing technologies based on enzyme electrochemical biosensors remains a great challenge. This article outlines the construction principles of four generations of enzyme electrochemical biosensors and discusses the applications of single-enzyme systems, multi-enzyme systems, and nano-enzyme systems developed based on these principles. The article further describes methods to improve enzyme immobilization by combining different types of nanomaterials such as metals and their oxides, graphene-related materials, metal-organic frameworks, carbon nanotubes, and conducting polymers. In addition, the article highlights the challenges and future trends of enzyme electrochemical biosensors, providing theoretical support and future perspectives for further research and development of high-performance enzyme chemical biosensors.

A novel tunable metal-clad planar waveguide with 0.62PMN-0.38PT material for detection of cancer cells

A dynamically tunable metal clad planar waveguide having 0.62PMN-0.38PT material is simulated and optimized for detection of cancer cells. Angular interrogation of the TE0 mode of waveguide shows that critical angle increases greater than the resonance angle with increasing of cover refractive index, which limits the detection range of waveguide. To overcome this limitation, proposed waveguide applies a potential on the PMN-PT adlayer. Although a sensitivity of 105.42 degree/RIU was achieved at 70 Volts in testing the proposed waveguide, it was found that the optimal performance parameters were obtained at 60 Volts. At this voltage, the waveguide demonstrated detection range 1.3330-1.5030, a detection accuracy 2393.33, and a figure of merit 2243.59 RIU-1 , which enabled the detection of the entire range of the targeted cancer cells. Therefore, it is recommended to apply a potential of 60 Volts to achieve the best performance from the proposed waveguide.

Recent advances in rare earth ion-doped upconversion nanomaterials: From design to their applications in food safety analysis

The misuse of chemicals in agricultural systems and food production leads to an increase in contaminants in food, which ultimately has adverse effects on human health. This situation has prompted a demand for sophisticated detection technologies with rapid and sensitive features, as concerns over food safety and quality have grown around the globe. The rare earth ion-doped upconversion nanoparticle (UCNP)-based sensor has emerged as an innovative and promising approach for detecting and analyzing food contaminants due to its superior photophysical properties, including low autofluorescence background, deep penetration of light, low toxicity, and minimal photodamage to the biological samples. The aim of this review was to discuss an outline of the applications of UCNPs to detect contaminants in food matrices, with particular attention on the determination of heavy metals, pesticides, pathogenic bacteria, mycotoxins, and antibiotics. The review briefly discusses the mechanism of upconversion (UC) luminescence, the synthesis, modification, functionality of UCNPs, as well as the detection principles for the design of UC biosensors. Furthermore, because current UCNP research on food safety detection is still at an early stage, this review identifies several bottlenecks that must be overcome in UCNPs and discusses the future prospects for its application in the field of food analysis.

Electrochemical Biosensors for the Detection of Antibiotics in Milk: Recent Trends and Future Perspectives

Antibiotics have emerged as ground-breaking medications for the treatment of infectious diseases, but due to the excessive use of antibiotics, some drugs have developed resistance to microorganisms. Because of their structural complexity, most antibiotics are excreted unchanged, polluting the water, soil, and natural resources. Additionally, food items are being polluted through the widespread use of antibiotics in animal feed. The normal concentrations of antibiotics in environmental samples typically vary from ng to g/L. Antibiotic residues in excess of these values can pose major risks the development of illnesses and infections/diseases. According to estimates, 300 million people will die prematurely in the next three decades (by 2050), and the WHO has proclaimed "antibiotic resistance" to be a severe economic and sociological hazard to public health. Several antibiotics have been recognised as possible environmental pollutants (EMA) and their detection in various matrices such as food, milk, and environmental samples is being investigated. Currently, chromatographic techniques coupled with different detectors (e.g., HPLC, LC-MS) are typically used for antibiotic analysis. Other screening methods include optical methods, ELISA, electrophoresis, biosensors, etc. To minimise the problems associated with antibiotics (i.e., the development of AMR) and the currently available analytical methods, electrochemical platforms have been investigated, and can provide a cost-effective, rapid and portable alternative. Despite the significant progress in this field, further developments are necessary to advance electrochemical sensors, e.g., through the use of multi-functional nanomaterials and advanced (bio)materials to ensure efficient detection, sensitivity, portability, and reliability. This review summarises the use of electrochemical biosensors for the detection of antibiotics in milk/milk products and presents a brief introduction to antibiotics and AMR followed by developments in the field of electrochemical biosensors based on (i) immunosensor, (ii) aptamer (iii) MIP, (iv) enzyme, (v) whole-cell and (vi) direct electrochemical approaches. The role of nanomaterials and sensor fabrication is discussed wherever necessary. Finally, the review discusses the challenges encountered and future perspectives. This review can serve as an insightful source of information, enhancing the awareness of the role of electrochemical biosensors in providing information for the preservation of the health of the public, of animals, and of our environment, globally.

Recent Advances of Biosensors for Detection of Multiple Antibiotics

The abuse of antibiotics has caused a serious threat to human life and health. It is urgent to develop sensors that can detect multiple antibiotics quickly and efficiently. Biosensors are widely used in the field of antibiotic detection because of their high specificity. Advanced artificial intelligence/machine learning algorithms have allowed for remarkable achievements in image analysis and face recognition, but have not yet been widely used in the field of biosensors. Herein, this paper reviews the biosensors that have been widely used in the simultaneous detection of multiple antibiotics based on different detection mechanisms and biorecognition elements in recent years, and compares and analyzes their characteristics and specific applications. In particular, this review summarizes some AI/ML algorithms with excellent performance in the field of antibiotic detection, and which provide a platform for the intelligence of sensors and terminal apps portability. Furthermore, this review gives a short review of biosensors for the detection of multiple antibiotics.

Facile synthesis of core-shell Co-MOF with hierarchical porosity for enhanced electrochemical detection of furaltadone in aquaculture water

Metal-organic frameworks (MOFs) exhibited huge application potential in electrochemical analysis field, how to facilely and effectively boost the electrochemical sensing activity of MOFs materials still face enormous challenges. In this work, core-shell Co-MOF (Co-TCA@ZIF-67) polyhedrons with hierarchical porosity was easily synthesized via simple chemical etching reaction by selecting thiocyanuric acid as the etching reagent. Benefiting from the introduction of mesopores and thiocyanuric acid/Co²⁺ complex on the surface of ZIF-67 frameworks, the property and functions of the pristine ZIF-67 was seriously tailored. Compared with the pristine ZIF-67, the as-resulted Co-TCA@ZIF-67 nanoparticles displayed greatly enhanced physical adsorption capacity and electrochemical reduction activity toward the antibiotic drug furaltadone. As a result, a novel furaltadone electrochemical sensor with high sensitivity was fabricated. The linear detection range was from 50 nM to 5 μM with sensitivity of 110.40 μA^-1 μM^-1 cm^-2 and detection limit of 12 nM. This work demonstrated chemical etching strategy is truly a facile and effective way to modify the electrochemical sensing performance of MOFs-based materials, and we believed the chemically etched MOFs materials will play a stronger role in terms of food safety and environmental conservation.

Occurrence of antibiotics in wastewater: Potential ecological risk and removal through anaerobic-aerobic systems

Antibiotics are intensively used to improve public health, prevent diseases and enhance productivity in animal farms. Contrarily, when released, the antibiotics laden wastewater produced from pharmaceutical industries and their application sources poses a potential ecological risk to the environment. This study provides a discussion on the occurrence of various antibiotics in wastewater and their potential ecological risk in the environment. Further, a critical review of anaerobic-aerobic processes based on three major systems (such as constructed wetland, high-rate bioreactor, and integrated treatment technologies) applied for antibiotics removal from wastewater is performed. The review also explores microbial dynamics responsible for antibiotic biodegradation in anaerobic-aerobic systems and its economic feasibility at wider-scale applications. The operational problems and prospective modifications are discussed to define key future research directions. The appropriate selection of treatment processes, sources control, understanding of antibiotic fate, and adopting precise monitoring strategies could eliminate the potential ecological risks of antibiotics. Integrated bio-electrochemical systems exhibit antibiotics removal ≥95% by dominant Geobacter sp. at short HRT ∼4-10 h. Major process factors like organic loading rate, hydraulic loading rate (HRT), and solid retention time significantly affect the system performance. This review will be beneficial to the researchers by providing in-depth understanding of antibiotic pollution and its abatement via anaerobic-aerobic processes to develop sustainable wastewater treatment technology in the future.

Green-derived carbon dots: A potent tool for biosensing in food safety

The impact of food contaminants on ecosystems and human health has attracted widespread global attention, and there is an urgent need to develop reliable food safety detection methods. Recently, carbon dots (CDs) have been considered as a powerful material to construct sensors for chemical analysis. Based on the concept of resource conversion and sustainable development, the use of natural, harmless, and renewable materials for the preparation of CDs without the involvement of chemical hazards is a current hot topic. This paper reviews the research progress of green-derived CDs and their application in food safety biosensing. The fabrications of green-derived CDs using various biomasses are described in detail, and the application of CDs especially the sensing mechanisms of photoluminescence, colorimetric, electrochemiluminescence and other sensors are provided. Finally, existing shortcomings and current challenges as well as prospects for food safety monitoring are discussed. We believe that this work provides strong insight into the application of CDs in the sensing of various contaminants.

Development of europium(III) complex functionalized silica nanoprobe for luminescence detection of tetracycline

Increasing awareness of the health and environment impacts of the antibiotics misuse or overuse, such as tetracycline (TC) in treatment or prevention of infections and diseases, has driven the development of robust methods for their detection in biological, environmental and food systems. In this work, we report the development of a new europium(III) complex functionalized silica nanoprobe (SiNPs-Eu³⁺) for highly sensitive and selective detection of TC residue in aqueous solution and food samples (milk and meat). The nanoprobe is developed by immobilization of Eu³⁺ ion onto the surface of silica nanoparticles (SiNPs) as the emitter and TC recognition unit. The β-diketone configuration of TC can further coordinate with Eu³⁺ steadily on the surface of nanoprobe, facilitating the absorption of light excitation for Eu³⁺ emitter activation and luminescence "off-on" response. The dose-dependent luminescence enhancement of SiNPs-Eu³⁺ nanoprobe exhibits good linearities, allowing the quantitative detection of TC. The SiNPs-Eu³⁺ nanoprobe shows high sensitivity and selectivity for TC detection in buffer solution. Time resolved luminescence analysis enables the elimination of autofluorescence and light scattering for highly sensitive detection of TC in milk and pork mince with high accuracy and precision. The successful development of SiNPs-Eu³⁺ nanoprobe is anticipated to provide a rapid, economic, and robust approach for TC detection in real world samples.

Integration of Metallic Nanomaterials and Recognition Elements for the Specifically Monitoring of Pesticides in Electrochemical Sensing

Although all countries have been controlling the excessive use of pesticides, incidents of pesticide residues still existed. Electrochemical biosensors are extensively applied detection techniques to monitor pesticides with the help of different types of biorecognition components mainly including, antibodies, aptamers, enzymes (i.e., acetylcholinesterase, organophosphorus hydrolase, etc.), and synthetic molecularly imprinted polymers. Besides, the electrode materials mainly affected the sensitivity of electrochemical biosensors. Metallic nanomaterials with various structures and excellent electrical conductivity were desirable choice to construct electrochemical platforms to achieve the detection with high sensitivity and good specificity toward the target. This work reviewed the developed metallic materials including monometallic nanoparticles, bimetallic nanomaterials, metal atoms, metal oxides, metal molybdates, metal-organic frameworks, MXene, etc. Integration of recognition elements endowed the electrode materials with higher specificity toward the target pesticide. Besides, future challenges of metallic nanomaterials-based electrochemical biosensors for the detection of pesticides are also discussed and described.

Different Strategies for the Microfluidic Purification of Antibiotics from Food: A Comparative Study

The presence of residual antibiotics in food is increasingly emerging as a worrying risk for human health both for the possible direct toxicity and for the development of antibiotic-resistant bacteria. In the context of food safety, new methods based on microfluidics could offer better performance, providing improved rapidity, portability and sustainability, being more cost effective and easy to use. Here, a microfluidic method based on the use of magnetic microbeads specifically functionalized and inserted in polymeric microchambers is proposed. The microbeads are functionalized either with aptamers, antibodies or small functional groups able to interact with specific antibiotics. The setup of these different strategies as well as the performance of the different functionalizations are carefully evaluated and compared. The most promising results are obtained employing the functionalization with aptamers, which are able not only to capture and release almost all tetracycline present in the initial sample but also to deliver an enriched and simplified solution of antibiotic. These solutions of purified antibiotics are particularly suitable for further analyses, for example, with innovative methods, such as label-free detection. On the contrary, the on-chip process based on antibodies could capture only partially the antibiotics, as well as the protocol based on beads functionalized with small groups specific for sulfonamides. Therefore, the on-chip purification with aptamers combined with new portable detection systems opens new possibilities for the development of sensors in the field of food safety.

A Minireview for Recent Development of Nanomaterial-Based Detection of Antibiotics

Antibiotics are considered a new type of organic pollutant. Antibiotic residues have become a global issue due to their harm to human health. As the use of antibiotics is increasing in human life, such as in medicine, crops, livestock, and even drinking water, the accurate analysis of antibiotics is very vital. In order to develop rapid and on-site approaches for the detection of antibiotics and the analysis of trace-level residual antibiotics, a high-sensitivity, simple, and portable solution is required. Meanwhile, the rapid nanotechnology development of a variety of nanomaterials has been achieved. In this review, nanomaterial-based techniques for antibiotic detection are discussed, and some reports that have employed combined nanomaterials with optical techniques or electrochemical techniques are highlighted.

Caenorhabditis elegans: a model organism in the toxicity assessment of environmental pollutants

The unfavorable effects of environmental pollutants are becoming increasingly evident. In recent years, Caenorhabditis elegans (C. elegans) has been used as a powerful terrestrial model organism for environmental toxicity studies owing to its various advantages, including ease of culture, short lifespan, small size, transparent body, and well-characterized genome. In vivo bioassays and field studies can analyze and evaluate various toxic effects of the toxicants on the model organism, while emerging technologies allow profound insights into molecular disturbances underlying the observed phenotypes. In this review, we discuss the applications of C. elegans as a model organism in environmental toxicity studies and delineate apical assays such as lifespan, growth rate, reproduction, and locomotion, which are widely used in toxicity evaluation. In addition to phenotype assays, a comprehensive understanding of the toxic mode of action and mechanism can be achieved through a highly sensitive multi-omics approach, including the expression levels of genes and endogenous metabolites. Recent studies on environmental toxicity using these approaches have been summarized. This review highlights the practicality and advantages of C. elegans in evaluating the toxicity of environmental pollutants and presents the findings of recent toxicity studies performed using this model organism. Finally, we propose crucial technical considerations to escalate the appropriate use of C. elegans in examining the toxic effects of environmental pollutants.

Emerging Trends of Electrochemical Sensors in Food Analysis

Food quality and safety pose an increasing threat to human health worldwide [...]

A surface plasmon resonance sensor with synthetic receptors decorated on graphene oxide for selective detection of benzylpenicillin

Antibiotic residues in foods, water and the environment reveal antibiotic-resistant bacterial strains, disrupting the ecological balance and causing serious health problems. For these reasons, the detection of antibiotic residues is crucial for the protection of human health. Herein, the detection of benzylpenicillin antibiotic from aqueous and milk sample solutions was carried out by surface plasmon resonance (SPR) sensor using synthetic receptor-molecularly imprinted polymer. The benzylpenicillin-imprinted poly(hydroxyethyl methacrylate-graphene oxide-N-methacryloyl-l-phenylalanine) (MIP-GO) SPR sensor was prepared. Benzylpenicillin detection was performed by MIP-GO SPR sensor in a 1-100 ppb concentration range of benzylpenicillin with 0.9665 linear correlation and 0.021 ppb detection limit. Selectivity analysis showed that the MIP-GO SPR sensor detected the benzylpenicillin molecule 8.16 times more selectively than amoxicillin and 14.04 times more selectively than ampicillin. To examine the imprinting efficiency, non-imprinted poly(hydroxyethyl methacrylate-graphene oxide-N-methacryloyl-l-phenylalanine) (NIP-GO) SPR sensor was also prepared using the same procedure without benzylpenicillin addition. Since graphene oxide (GO) was added to enhance the sensor signal response by increasing sensitivity, the control analyses were performed by a poly(hydroxyethyl methacrylate-N-methacryloyl-l-phenylalanine) (MIP) SPR sensor without adding GO. Moreover, repeatability studies of MIP-GO SPR sensor were statistically evaluated and the RSD of intra-day assays less than 1% specified that there was no loss of performance for the benzylpenicillin detection ability even after four cycles. As a real food sample analysis, the benzylpenicillin spiked and unspiked milk samples were evaluated and high-performance liquid chromatography experiments were carried out for validation.

Multiresidues Multiclass Analytical Methods for Determination of Antibiotics in Animal Origin Food: A Critical Analysis

Veterinary drugs are widely used to prevent and treat diseases. The European Union has forbidden the use of antibiotics as growth promoters since 2006. Its abusive use leads to the presence of antibiotic residues (AR) in foods of animal origin which is associated with antibiotic resistance. The monitoring of AR in food intended for human consumption is of utmost importance to assure Food Safety. A systematic bibliographic review was carried out on the analytical methodologies, published in 2013, for the determination of AR in foods of animal origin. The food processing effect in the AR detected in animal products is also addressed. However, there is a preference for multiresidues multiclass methods, i.e., methodologies that allow determining simultaneously different classes of antibiotics, which is still a challenge for researchers. The wide diversity of physico-chemical properties of these drugs is an obstacle to achieving excellent analytical performance for a vast number of molecules analyzed concurrently. New techniques in sample preparation continue to be developed in order to obtain a compromise between good recoveries and extracts without interferences (clean extracts). The most widely used analytical methodology for the determination of AR is liquid chromatography coupled with mass spectrometry. However, the current trend is focused on the use of powerful high-resolution MS detectors such as Time of Flight and Orbitrap with modern chromatographic systems. Cooking time and temperature control are the key processing conditions influencing the reduction of AR in foods.

State of the Art on Developments of (Bio)Sensors and Analytical Methods for Rifamycin Antibiotics Determination

This review summarizes the literature data reported from 2000 up to the present on the development of various electrochemical (voltammetric, amperometric, potentiometric and photoelectrochemical), optical (UV-Vis and IR) and luminescence (chemiluminescence and fluorescence) methods and the corresponding sensors for rifamycin antibiotics analysis. The discussion is focused mainly on the foremost compound of this class of macrocyclic drugs, namely rifampicin (RIF), which is a first-line antituberculosis agent derived from rifampicin SV (RSV). RIF and RSV also have excellent therapeutic action in the treatment of other bacterial infectious diseases. Due to the side-effects (e.g., prevalence of drug-resistant bacteria, hepatotoxicity) of long-term RIF intake, drug monitoring in patients is of real importance in establishing the optimum RIF dose, and therefore, reliable, rapid and simple methods of analysis are required. Based on the studies published on this topic in the last two decades, the sensing principles, some examples of sensors preparation procedures, as well as the performance characteristics (linear range, limits of detection and quantification) of analytical methods for RIF determination, are compared and correlated, critically emphasizing their benefits and limitations. Examples of spectrometric and electrochemical investigations of RIF interaction with biologically important molecules are also presented.

Aptamer recognition-promoted specific intercalation of iridium complexes in G-quadruplex DNA for label-free and enzyme-free phosphorescence analysis of kanamycin

In consideration of relevance of antibiotic with food security, it is extremely desirable to propose sensitive and credible methods for antibiotic screening. Nevertheless, most of known approaches are developed based on fluorescence technique, which suffered from the interferences of background fluorescence and autoluminescence, and tedious labeling procedures, ascribing to the deficiency of high-performance and multifunctional dyes. Herein, we developed a novel iridium (III) complex (Ir-QAU)-based aptamer-promoted phosphorescence sensor for label-free, enzyme-free and highly sensitive detection of target antibiotic (kanamycin, Kan) based on target-switched hybridizing chain reaction (HCR). Ir-QAU was elaborately devised to present a signal-on response to G-quadruplex (G4) DNA against other DNAs due to its specific intercalation in G4 DNA and subsequent restriction of intra-molecular rotation. The recognition of H1 by Kan promoted the formation of Kan@H1 complexes, which hybridized with H2 and H3 via toehold-mediated hybridization reaction, subsequently switching HCR to produce large numbers of G4 DNA. Compared to Kan absence, abundant Ir-QAU was locked in G4 DNA to yield a significantly increased luminescence, which switches the luminescence analysis process of Kan with a limit of detection down to 0.38 pM. Furthermore, the Ir-QAU-based sensor was triumphantly applied to detect Kan in milk sample. We anticipate this work will disclose a new way to development of high-efficiency and practical luminescence sensor, and show a great potential for antibiotic-related food security.

Recent Progress in Nanotechnology-Based Approaches for Food Monitoring

Throughout the food supply chain, including production, storage, and distribution, food can be contaminated by harmful chemicals and microorganisms, resulting in a severe threat to human health. In recent years, the rapid advancement and development of nanotechnology proposed revolutionary solutions to solve several problems in scientific and industrial areas, including food monitoring. Nanotechnology can be incorporated into chemical and biological sensors to improve analytical performance, such as response time, sensitivity, selectivity, reliability, and accuracy. Based on the characteristics of the contaminants and the detection methods, nanotechnology can be applied in different ways in order to improve conventional techniques. Nanomaterials such as nanoparticles, nanorods, nanosheets, nanocomposites, nanotubes, and nanowires provide various functions for the immobilization and labeling of contaminants in electrochemical and optical detection. This review summarizes the recent advances in nanotechnology for detecting chemical and biological contaminations in the food supply chain.

Label-free fluorescence aptasensor for the detection of patulin using target-induced DNA gates and TCPP/BDC-NH2 mixed ligands functionalized Zr-MOF systems

Patulin (PAT) is an unsaturated lactone mycotoxin primarily produced by Penicillium expansum and Aspergillus clavatus. Given the potential health risks and economic losses associated with PAT, the rapid detection of PAT using fluorescent aptasensors is of significant importance in evaluating food safety. However, it easily increases the cost and complexity caused by signal labeling. We combined TCPP/BDC-NH₂ mixed ligands functionalized Zr metal-organic frameworks (Zr-MOF_mix) and terminated three-stranded DNA gates (ttsDNA gates) to fabricate a label-free fluorescent aptasensor for PAT detection. The Zr-MOF_mix system was synthesized via a one-pot strategy and could be used to address the problem of pore size limitation and increase the loading amounts of dyes. TtsDNA gate was integrated into the Zr-MOF_mix system to control the release of dyes, exhibiting a high signal-to-background ratio. The single-stranded aptamer region in ttsDNA gate situated away from the surface of the Zr-MOF_mix, resulting in a natural release of dyes in the absence of PAT. While binding to PAT resulted in target-induced conformational changes that helped form the hairpin structure of the aptamer. This structure hindered the release of dyes from the pores of Zr-MOF_mix, thus reducing the fluorescence signals intensity. The stimuli-responsive DNA-gated material provides a platform for PAT analysis under conditions of a low limit of detection (0.871 pg/mL). Furthermore, the excellent specificity and anti-interference of the fluorescent aptasensor make the system suitable for the analysis of apple juice samples. This label-free strategy is cheaper and simper compared with labeled detection, especially for the development of multi-target-detection.

Ultrasensitive, label-free voltammetric determination of norfloxacin based on molecularly imprinted polymers and Au nanoparticle-functionalized black phosphorus nanosheet nanocomposite

Norfloxacin (NOR) is an antibiotic commonly used to treat humans and food-producing animals. Owing to NOR abuse, its residues are frequently found in animal-derived food products and the surrounding environment. Therefore, development of an efficient analytical technique for the selective determination of trace NOR is greatly significant for food safety and environmental protection. Here, we fabricated an ultrasensitive, label-free molecularly imprinted polymer (MIP) voltammetric sensor for the selective determination of NOR, based on an Au nanoparticle-functionalized black phosphorus nanosheet nanocomposite (BPNS-AuNP) covered by a polypyrrole-imprinted film. BPNS-AuNP nanocomposites were prepared via an in-situ one-step method without the use of reducing agents. The imprinted polypyrrole film was formed on the surface of the BPNS-AuNPs in the presence of NOR. The physical properties and electrochemical behavior of the MIP/BPNS-AuNPs were investigated using various characterization techniques, and the analytical parameters were optimized. We found that BPNS-AuNPs improve the ambient stability and electrocatalytic activity, providing a large surface area for locating a higher number of specific recognition sites. Consequently, the MIP/BPNS-AuNP/GCE showed excellent sensing performance toward NOR, with a wide linear response range (0.1 nM - 10 μM), an extremely low limit of detection (0.012 nM), and extraordinary selectivity. Moreover, the MIP/BPNS-AuNP/GCE was used to determine NOR in various experimental samples with satisfactory results.