Electrochemical Immunosensors for Antibiotic Detection

Multiplex electrochemical aptasensor for the simultaneous detection of linomycin and neomycin antibiotics

The escalating use of antibiotics across diverse sectors, including human healthcare, agriculture, and livestock, has led to their pervasive presence in the environment, raising concerns about their impact on ecosystems and human health. Traditional detection methods, reliant on high-performance liquid chromatography and immuno-assays, face challenges of complexity, cross-reactivity, and limited specificity. Aptamer-based biosensors offer a promising alternative, leveraging the specificity, stability, and cost-effectiveness of aptamers. Herein, we present a novel dual-screen-printed carbon electrode (SPCE) biosensor, modified with a nanocomposite of gold nanoparticles (AuNPs) and carbon nanofibers (CNFs), for the label-free electrochemical detection of lincomycin and neomycin antibiotics. Lincomycin and neomycin, two antibiotics of environmental concern due to their widespread usage and potential ecological impact, were simultaneously detected using square wave voltammetry. The aptasensors showed high sensitivity with detection limits of 0.02 pg/mL and 0.035 pg/mL for lincomycin and neomycin, respectively. The developed biosensor exhibited high selectivity and reproducibility in detecting both antibiotics. This multiplex biosensing platform offers a promising strategy for efficient and cost-effective monitoring of antibiotic residues in environmental samples, addressing the critical need for robust detection methods in environmental monitoring and public health surveillance.

Efficient removal of chlortetracycline hydrochloride and doxycycline hydrochloride from aqueous solution by ZIF-67

ZIF-67 nanoparticles were synthesized by a simple method at room temperature and used to remove chlortetracycline hydrochloride (CTC) and doxycycline hydrochloride (DOX) from water. ZIF-67 was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FT-IR), Brunauer-Emmett-Teller (BET) surface area, X-ray photoelectron spectroscopy (XPS), thermogravimetry (TGA) and zeta potential analyzer. The morphology and chemical composition of the synthesized ZIF-67 were characterized. The effects of key parameters such as pH, dosage, temperature, contact time, different initial concentrations and coexisting ions on the adsorption behavior were systematically studied. The results of batch adsorption experiments indicate that the adsorption process conforms to the pseudo-second-order kinetic model and Sips model. At 303K, the removal rates of CTC and DOX at 150 mg/L reached 99.16 % and 97.61 %, and the maximum adsorption capacity of CTC and DOX reached 1411.68 and 1073.28 mg/g, respectively. At the same time, ZIF-67 has excellent stability and reusability. Most importantly, the possible adsorption mechanism is proposed by exploring the changes of SEM, TEM, BET and FT-IR characterization results before and after the reaction, which mainly includes pore filling, electrostatic interaction and π-π interaction. The prepared ZIF-67 has a large specific surface area (1495.967 m2 g-1), achieves a high removal rate within a short time frame, and maintains a high removal rate across a wide pH range. These characteristics make ZIF-67 a potentially promising adsorbent for removing antibiotics from aqueous solutions.

Electrochemical Sensors for Antibiotic Detection: A Focused Review with a Brief Overview of Commercial Technologies

Antimicrobial resistance (AMR) poses a significant threat to global health, powered by pathogens that become increasingly proficient at withstanding antibiotic treatments. This review introduces the factors contributing to antimicrobial resistance (AMR), highlighting the presence of antibiotics in different environmental and biological matrices as a significant contributor to the resistance. It emphasizes the urgent need for robust and effective detection methods to identify these substances and mitigate their impact on AMR. Traditional techniques, such as liquid chromatography-mass spectrometry (LC-MS) and immunoassays, are discussed alongside their limitations. The review underscores the emerging role of biosensors as promising alternatives for antibiotic detection, with a particular focus on electrochemical biosensors. Therefore, the manuscript extensively explores the principles and various types of electrochemical biosensors, elucidating their advantages, including high sensitivity, rapid response, and potential for point-of-care applications. Moreover, the manuscript investigates recent advances in materials used to fabricate electrochemical platforms for antibiotic detection, such as aptamers and molecularly imprinted polymers, highlighting their role in enhancing sensor performance and selectivity. This review culminates with an evaluation and summary of commercially available and spin-off sensors for antibiotic detection, emphasizing their versatility and portability. By explaining the landscape, role, and future outlook of electrochemical biosensors in antibiotic detection, this review provides insights into the ongoing efforts to combat the escalating threat of AMR effectively.

High-sensitively fluorescent switch-type sensing for Ag+ and halide anions of 2D Cd-based network constructed with logic gates

Effective detection of the concentration of Ag+ ions in bactericidal fluid is one of the necessary conditions for their effective utilization for sterilization. A novel 2D Cd(II) coordination polymer (CP1), named as [Cd(HDPN)(4,4'-bbpy)]·2H2O, was hydrothermally synthesized using 5-(2',4'-dicarboxylphenyl) nicotic acid (H3DPN) and 4,4'-bis(imidazolyl)biphenyl (4,4'-bbpy). The structure analysis discovered that CP1 possessed a 2D network structure of dinuclear inorganic building blocks. Fluorescence sensing discovered that CP1 could high-sensitively detect Ag+, tetracycline, nitrobenzene and pyrimethanil and the lowest limit of detection (LOD) were 1.44 × 10-8M, 2.15 × 10-8M, 8.09 × 10-8M, and 2.54 × 10-7M, respectively. It is worth noting that the quenching occurs after the addition of Ag+ to the aqueous solution of CP1, and then it gradually recovers when one of the halide anions (X- = Cl-, Br- and I-) is added, forming a unique "on-off-on" fluorescence sensor for Ag+ and constructing a simple logic gate. The fluorescence sensing mechanism of CP1 was investigated using ultraviolet-visible spectroscopy, PXRD, XPS, and DFT methods. The research indicates that CP1 is anticipated to serve as an excellent multifunctional fluorescence sensor, especially as a switch-type sensor for Ag+ and the halide anions.

Dual-channel fluorescent sensors based on chitosan-coated Mn-doped ZnS micromaterials to detect ampicillin

The global threat of antibiotic resistance has increased the importance of the detection of antibiotics. Conventional methods to detect antibiotics are time-consuming and require expensive specialized equipment. Here, we present a simple and rapid biosensor for detecting ampicillin, a commonly used antibiotic. Our method is based on the fluorescent properties of chitosan-coated Mn-doped ZnS micromaterials combined with the β-lactamase enzyme. The biosensors exhibited the highest sensitivity in a linear working range of 13.1-72.2 pM with a limit of detection of 8.24 pM in deionized water. In addition, due to the biological specificity of β-lactamase, the proposed sensors have demonstrated high selectivity over penicillin, tetracycline, and glucose through the enhancing and quenching effects at wavelengths of 510 nm and 614 nm, respectively. These proposed sensors also showed promising results when tested in various matrices, including tap water, bottled water, and milk. Our work reports for the first time the cost-effective (Mn:ZnS)Chitosan micromaterial was used for ampicillin detection. The results will facilitate the monitoring of antibiotics in clinical and environmental contexts.

Co-based Nanozymatic Profiling: Advances Spanning Chemistry, Biomedical, and Environmental Sciences

Nanozymes, next-generation enzyme-mimicking nanomaterials, have entered an era of rational design; among them, Co-based nanozymes have emerged as captivating players over times. Co-based nanozymes have been developed and have garnered significant attention over the past five years. Their extraordinary properties, including regulatable enzymatic activity, stability, and multifunctionality stemming from magnetic properties, photothermal conversion effects, cavitation effects, and relaxation efficiency, have made Co-based nanozymes a rising star. This review presents the first comprehensive profiling of the Co-based nanozymes in the chemistry, biology, and environmental sciences. The review begins by scrutinizing the various synthetic methods employed for Co-based nanozyme fabrication, such as template and sol-gel methods, highlighting their distinctive merits from a chemical standpoint. Furthermore, a detailed exploration of their wide-ranging applications in biosensing and biomedical therapeutics, as well as their contributions to environmental monitoring and remediation is provided. Notably, drawing inspiration from state-of-the-art techniques such as omics, a comprehensive analysis of Co-based nanozymes is undertaken, employing analogous statistical methodologies to provide valuable guidance. To conclude, a comprehensive outlook on the challenges and prospects for Co-based nanozymes is presented, spanning from microscopic physicochemical mechanisms to macroscopic clinical translational applications.

Advances and Challenges in Nanomaterial-Based Electrochemical Immunosensors for Small Cell Lung Cancer Biomarker Neuron-Specific Enolase

Early and rapid detection of neuron-specific enolase (NSE) is highly significant, as it is putative biomarker for small-cell lung cancer as well as COVID-19. Electrochemical techniques have attracted substantial attention for the early detection of cancer biomarkers due to the important properties of simplicity, high sensitivity, specificity, low cost, and point-of-care detection. This work reviews the clinically relevant labeled and label-free electrochemical immunosensors developed so far for the analysis of NSE. The prevailing role of nanostructured materials as electrode matrices is thoroughly discussed. Subsequently, the key performances of various immunoassays are critically evaluated in terms of limit of detection, linear ranges, and incubation time for clinical translation. Electrochemical techniques coupled with screen-printed electrodes developing market level commercialization of NSE sensors is also discussed. Finally, the review concludes with the current challenges associated with available methods and provides a future outlook toward commercialization opportunities for easy detection of NSE.

Recent Trends in Nanomaterial Based Electrochemical Sensors for Drug Detection: Considering Green Assessment

An individual's therapeutic drug exposure level is directly linked to corresponding clinical effects. Rapid, sensitive, inexpensive, portable and reliable devices are needed for diagnosis related to drug exposure, treatment, and prognosis of diseases. Electrochemical sensors are useful for drug monitoring due to their high sensitivity and fast response time. Also, they can be combined with portable signal read-out devices for point-of-care applications. In recent years, nanomaterials such as carbon-based, carbon-metal nanocomposites, noble nanomaterials have been widely used to modify electrode surfaces due to their outstanding features including catalytic abilities, conductivity, chemical stability, biocompatibility for development of electrochemical sensors. This review paper presents the most recent advances about nanomaterials-based electrochemical sensors including the use of green assessment approach for detection of drugs including anticancer, antiviral, anti-inflammatory, and antibiotics covering the period from 2019 to 2023. The sensor characteristics such as analyte interactions, fabrication, sensitivity, and selectivity are also discussed. In addition, the current challenges and potential future directions of the field are highlighted.

Potential applications of green-synthesized iron oxide NPs for environmental remediation

Water pollution is a significant issue worldwide due to an increase in anthropogenic activities. Heavy metals and dyes are among the most problematic contaminants that threaten the environment and negatively impact human health. Iron oxide nanoparticles (IONPs) synthesized using green methods have shown potential in these areas due to their significant adsorption capacity and photocatalytic potential. The size and morphology of biogenic IONPs can be tailored depending upon the concentration of the reducing medium and metal salt precursor. Green-synthesized IONPs have been found to be effective, economical, and environmentally friendly with their large surface area, making them suitable for removing toxic matter from contaminated water. Furthermore, they exhibit antibacterial potential against harmful microorganisms. The study emphasizes the importance of using such environmentally friendly tools to remove heavy metal ions and organic compounds from contaminated water. The underlying mechanism for the adsorption of heavy metal ions, photocatalytic degradation of organic compounds, and antimicrobial action has been explored in detail. The future prospective for the beneficial utilization of biogenic IONPs has also been signified to provide a detailed overview.

Progress in Electrochemical Immunosensors with Alkaline Phosphatase as the Signal Label

Electrochemical immunosensors have shown great potential in clinical diagnosis, food safety, environmental protection, and other fields. The feasible and innovative combination of enzyme catalysis and other signal-amplified elements has yielded exciting progress in the development of electrochemical immunosensors. Alkaline phosphatase (ALP) is one of the most popularly used enzyme reporters in bioassays. It has been widely utilized to design electrochemical immunosensors owing to its significant advantages (e.g., high catalytic activity, high turnover number, and excellent substrate specificity). In this work, we summarized the achievements of electrochemical immunosensors with ALP as the signal reporter. We mainly focused on detection principles and signal amplification strategies and briefly discussed the challenges regarding how to further improve the performance of ALP-based immunoassays.

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.

The Method and Study of Detecting Phenanthrene in Seawater Based on a Carbon Nanotube-Chitosan Oligosaccharide Modified Electrode Immunosensor

Phenanthrene (PHE), as a structurally simple, tricyclic, polycyclic aromatic hydrocarbon (PAHs), is widely present in marine environments and organisms, with serious ecological and health impacts. It is crucial to study fast and simple high-sensitivity detection methods for phenanthrene in seawater for the environment and the human body. In this paper, a immunosensor was prepared by using a multi-wall carbon nanotube (MWCNTs)-chitosan oligosaccharide (COS) nanocomposite membrane loaded with phenanthrene antibody. The principle was based on the antibody-antigen reaction in the immune reaction, using the strong electron transfer ability of multi-walled carbon nanotubes, coupled with chitosan oligosaccharides with an excellent film formation and biocompatibility, to amplify the detection signal. The content of the phenanthrene in seawater was studied via differential pulse voltammetry (DPV) using a potassium ferricyanide system as a redox probe. The antibody concentration, pH value, and probe concentration were optimized. Under the optimal experimental conditions, the response peak current of the phenanthrene was inversely proportional to the concentration of phenanthrene, in the range from 0.5 ng·mL-1 to 80 ng·mL-1, and the detection limit was 0.30 ng·mL-1. The immune sensor was successfully applied to the detection of phenanthrene in marine water, with a recovery rate of 96.1~101.5%, and provided a stable, sensitive, and accurate method for the real-time monitoring of marine environments.

Novel Sensitive Electrochemical Immunosensor Development for the Selective Detection of HopQ H. pylori Bacteria Biomarker

Helicobacter pylori (H. pylori) is a highly contagious pathogenic bacterium that can cause gastrointestinal ulcers and may gradually lead to gastric cancer. H. pylori expresses the outer membrane HopQ protein at the earliest stages of infection. Therefore, HopQ is a highly reliable candidate as a biomarker for H. pylori detection in saliva samples. In this work, an H. pylori immunosensor is based on detecting HopQ as an H. pylori biomarker in saliva. The immunosensor was developed by surface modification of screen-printed carbon electrodes (SPCE) with MWCNT-COOH decorated with gold nanoparticles (AuNP) followed by HopQ capture antibody grafting on SPCE/MWCNT/AuNP surface using EDC/S-NHS chemistry. The sensor performance was investigated utilizing various methods, such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and scanning electron microscope (SEM) coupled with energy-dispersive X-ray spectroscopy (EDX). H. pylori detection performance in spiked saliva samples was evaluated by square wave voltammetry (SWV). The sensor is suitable for HopQ detection with excellent sensitivity and linearity in the 10 pg/mL-100 ng/mL range, with a 2.0 pg/mL limit of detection (LOD) and an 8.6 pg/mL limit of quantification (LOQ). The sensor was tested in saliva at 10 ng/mL, and recovery of 107.6% was obtained by SWV. From Hill's model, the dissociation constant Kd for HopQ/HopQ antibody interaction is estimated to be 4.60 × 10^-10 mg/mL. The fabricated platform shows high selectivity, good stability, reproducibility, and cost-effectiveness for H. pylori early detection due to the proper choice of biomarker, the nanocomposite material utilization to boost the SPCE electrical performance, and the intrinsic selectivity of the antibody-antigen approach. Additionally, we provide insight into possible future aspects that researchers are recommended to focus on.

Affinity-Based Analysis Methods for the Detection of Aminoglycoside Antibiotic Residues in Animal-Derived Foods: A Review

With the increasingly serious problem of aminoglycoside antibiotic residues, it is imperative to develop rapid, sensitive and efficient detection methods. This article reviews the detection methods of aminoglycoside antibiotics in animal-derived foods, including enzyme-linked immunosorbent assay, fluorescent immunoassay, chemical immunoassay, affinity sensing assay, lateral flow immunochromatography and molecular imprinted immunoassay. After evaluating the performance of these methods, the advantages and disadvantages were analyzed and compared. Furthermore, development prospects and research trends were proposed and summarized. This review can serve as a basis for further research and provide helpful references and new insights for the analysis of aminoglycoside residues. Accordingly, the in-depth investigation and analysis will certainly make great contributions to food safety, public hygiene and human health.

Identification of antibiotic residues in aquatic products with surface-enhanced Raman scattering powered by 1-D convolutional neural networks

Universal and fast antibiotic residues detection technology is imperative for the control of food safety in aquatic products. However, accurate surface-enhanced Raman scattering (SERS) quantitative detection of complicated samples is still a challenge. A recognition method powered by deep learning and took advantage of the unique fingerprint information merits of SERS was proposed. Herein, the spectra were collected by Ag nanofilm SERS substrate prepared by self-assembly of Ag nanoparticles on water/oil interface. A SERS-based database of commonly used antibiotics in aquatic products was set up, which is suitable for employed as input data for learning and training. The results show that the five types of antibiotics are successfully distinguished through principal component analysis (PCA) and each antibiotic in every type was successfully distinguished. Furthermore, one-dimensional convolutional neural networks (1-D CNN) was used to distinguish the antibiotics, and the results show that all the test samples were correctly predicted by 1-D CNN model. The results of this research suggest the great potential of the combination of SERS spectra with deep learning as a method for rapid and highly accurate identification of antibiotic residues in aquatic products.

Implants with Sensing Capabilities

Because of the aging human population and increased numbers of surgical procedures being performed, there is a growing number of biomedical devices being implanted each year. Although the benefits of implants are significant, there are risks to having foreign materials in the body that may lead to complications that may remain undetectable until a time at which the damage done becomes irreversible. To address this challenge, advances in implantable sensors may enable early detection of even minor changes in the implants or the surrounding tissues and provide early cues for intervention. Therefore, integrating sensors with implants will enable real-time monitoring and lead to improvements in implant function. Sensor integration has been mostly applied to cardiovascular, neural, and orthopedic implants, and advances in combined implant-sensor devices have been significant, yet there are needs still to be addressed. Sensor-integrating implants are still in their infancy; however, some have already made it to the clinic. With an interdisciplinary approach, these sensor-integrating devices will become more efficient, providing clear paths to clinical translation in the future.

Construction of Electrochemical Sensors for Antibiotic Detection Based on Carbon Nanocomposites

Excessive antibiotic residues in food can cause detrimental effects on human health. The establishment of rapid, sensitive, selective, and reliable methods for the detection of antibiotics is highly in demand. With the inherent advantages of high sensitivity, rapid analysis time, and facile miniaturization, the electrochemical sensors have great potential in the detection of antibiotics. The electrochemical platforms comprising carbon nanomaterials (CNMs) have been proposed to detect antibiotic residues. Notably, with the introduction of functional CNMs, the performance of electrochemical sensors can be bolstered. This review first presents the significance of functional CNMs in the detection of antibiotics. Subsequently, we provide an overview of the applications for detection by enhancing the electrochemical behaviour of the antibiotic, as well as a brief overview of the application of recognition elements to detect antibiotics. Finally, the trend and the current challenges of electrochemical sensors based on CNMs in the detection of antibiotics is outlined.

Hydrogel Nanoarchitectonics: An Evolving Paradigm for Ultrasensitive Biosensing

The integration of nanoarchitectonics and hydrogel into conventional biosensing platforms offers the opportunities to design physically and chemically controlled and optimized soft structures with superior biocompatibility, better immobilization of biomolecules, and specific and sensitive biosensor design. The physical and chemical properties of 3D hydrogel structures can be modified by integrating with nanostructures. Such modifications can enhance their responsiveness to mechanical, optical, thermal, magnetic, and electric stimuli, which in turn can enhance the practicality of biosensors in clinical settings. This review describes the synthesis and kinetics of gel networks and exploitation of nanostructure-integrated hydrogels in biosensing. With an emphasis on different integration strategies of hydrogel with nanostructures, this review highlights the importance of hydrogel nanostructures as one of the most favorable candidates for developing ultrasensitive biosensors. Moreover, hydrogel nanoarchitectonics are also portrayed as a promising candidate for fabricating next-generation robust biosensors.

Transducer Technologies for Biosensors and Their Wearable Applications

The development of new biosensor technologies and their active use as wearable devices have offered mobility and flexibility to conventional western medicine and personal fitness tracking. In the development of biosensors, transducers stand out as the main elements converting the signals sourced from a biological event into a detectable output. Combined with the suitable bio-receptors and the miniaturization of readout electronics, the functionality and design of the transducers play a key role in the construction of wearable devices for personal health control. Ever-growing research and industrial interest in new transducer technologies for point-of-care (POC) and wearable bio-detection have gained tremendous acceleration by the pandemic-induced digital health transformation. In this article, we provide a comprehensive review of transducers for biosensors and their wearable applications that empower users for the active tracking of biomarkers and personal health parameters.

Recent Advances in Sandwich SERS Immunosensors for Cancer Detection

Cancer has been one of the most prevalent diseases around the world for many years. Its biomarkers are biological molecules found in the blood or other body fluids of people with cancer diseases. These biomarkers play a crucial role not only in the diagnosis of cancer diseases, but also in risk assessment, selection of treatment methods, and tracking its progress. Therefore, highly sensitive and selective detection and determination of cancer biomarkers are essential from the perspective of oncological diagnostics and planning the treatment process. Immunosensors are special types of biosensors that are based on the recognition of an analyte (antigen) by an antibody. Sandwich immunosensors apply two antibodies: a capture antibody and a detection antibody, with the antigen ‘sandwiched’ between them. Immunosensors’ advantages include not only high sensitivity and selectivity, but also flexible application and reusability. Surface-enhanced Raman spectroscopy, known also as the sensitive and selective method, uses the enhancement of light scattering by analyte molecules adsorbed on a nanostructured surface. The combination of immunosensors with the SERS technique further improves their analytical parameters. In this article, we followed the recent achievements in the field of sandwich SERS immunosensors for cancer biomarker detection and/or determination.

Recent advances in the potential applications of luminescence-based, SPR-based, and carbon-based biosensors

Abstract

The need for biosensors has evolved in the detection of molecules, diseases, and pollution from various sources. This requirement has headed to the development of accurate and powerful equipment for analysis using biological sensing component as a biosensor. Biosensors have the advantage of rapid detection that can beat the conventional methods for the detection of the same molecules. Bio-chemiluminescence-based sensors are very sensitive during use in biological immune assay systems. Optical biosensors are emerging with time as they have the advantage that they act with a change in the refractive index. Carbon nanotube-based sensors are another area that has an important role in the biosensor field. Bioluminescence gives much higher quantum yields than classical chemiluminescence. Electro-generated bioluminescence has the advantage of miniature size and can produce a high signal-to-noise ratio and the controlled emission. Recent advances in biological techniques and instrumentation involving fluorescence tag to nanomaterials have increased the sensitivity limit of biosensors. Integrated approaches provided a better perspective for developing specific and sensitive biosensors with high regenerative potentials. This paper mainly focuses on sensors that are important for the detection of multiple molecules related to clinical and environmental applications.

Key points

• The review focusses on the applications of luminescence-based, surface plasmon resonance-based, carbon nanotube-based, and graphene-based biosensors

• Potential clinical, environmental, agricultural, and food industry applications/uses of biosensors have been critically reviewed

• The current limitations in this field are discussed, as well as the prospects for future advancement

Colorimetric detection of sulfamethazine based on target resolved calixarene derivative stabilized gold nanoparticles aggregation

Sulfamethazine (SMZ) is one of the most used broad-spectrum antibiotics owing to its low cost and high efficacy towards bacterial diseases. This workreports a novel label-free SMZ sensor based on para-sulfonatocalix[4]arene (pSC₄) capped gold nanoparticles (pSC₄-AuNPs) for colorimetric detection through the host-guest interaction. The existence of SMZ resulted in the aggregation of pSC₄-AuNPs and can be observed through colorimetric assay. A good linear relationship in the range 2.5 ~ 20 nM was obtained with a correlation coefficient of 0.9908. The limit of detection for SMZ was 1.39 nM. High recoveries (90.18-107.06%) were obtained, and RSD ranged from 1.21 to 2.05%. The color changes can be observed from red to gray within 10 min. Combining the supermolecule's recognition and AuNP's optical performance, the method paves a new, easy, and rapid way for small target sensing.

Electrochemical Synthesis of Zinc Oxide Nanostructures on Flexible Substrate and Application as an Electrochemical Immunoglobulin-G Immunosensor

Immunoglobulin G (IgG), a type of antibody, represents approximately 75% of serum antibodies in humans, and is the most common type of antibody found in blood circulation. Consequently, the development of simple, fast and reliable systems for IgG detection, which can be achieved using electrochemical sandwich-type immunosensors, is of considerable interest. In this study we have developed an immunosensor for human (H)-IgG using an inexpensive and very simple fabrication method based on ZnO nanorods (NRs) obtained through the electrodeposition of ZnO. The ZnO NRs were treated by electrodepositing a layer of reduced graphene oxide (rGO) to ensure an easy immobilization of the antibodies. On Indium Tin Oxide supported on Polyethylene Terephthalate/ZnO NRs/rGO substrate, the sandwich configuration of the immunosensor was built through different incubation steps, which were all optimized. The immunosensor is electrochemically active thanks to the presence of gold nanoparticles tagging the secondary antibody. The immunosensor was used to measure the current density of the hydrogen development reaction which is indirectly linked to the concentration of H-IgG. In this way the calibration curve was constructed obtaining a logarithmic linear range of 10-1000 ng/mL with a detection limit of few ng/mL and good sensitivity.

Selective Detection of Penicillin G Antibiotic in Milk by Molecularly Imprinted Polymer-Based Plasmonic SPR Sensor

Molecularly imprinted polymer-based surface plasmon resonance sensor prepared using silver nanoparticles was designed for the selective recognition of Penicillin G (PEN-G) antibiotic from both aqueous solution and milk sample. PEN-G imprinted sensors (NpMIPs) SPR sensor was fabricated using poly (2-hydroxyethyl methacrylate-N-methacroyl-(L)-cysteine methyl ester)-silver nanoparticles-N-methacryloyl-L-phenylalanine methyl ester polymer by embedding silver nanoparticles (AgNPs) into the polymeric film structure. In addition, a non-imprinted (NpNIPs) SPR sensor was prepared by utilizing the same polymerization recipe without addition of the PEN-G template molecule to evaluate the imprinting effect. FTIR-ATR spectrophotometer, ellipsometer, contact angle measurements were used for the characterization of NpMIPs SPR sensors. The linear concentration range of 0.01–10 ng/mL PEN-G was studied for kinetic analyses. The augmenting effect of AgNPs used to increase the surface plasmon resonance signal response was examined using polymer-based PEN-G imprinted (MIPs) sensor without the addition of AgNPs. The antibiotic amount present in milk chosen as a real sample was measured by spiking PEN-G into the milk. According to the Scatchard, Langmuir, Freundlich and Langmuir–Freundlich adsorption models, the interaction mechanism was estimated to be compatible with the Langmuir model.

Environmental fate of tetracycline antibiotics: degradation pathway mechanisms, challenges, and perspectives

Tetracycline pollution is a growing global threat to aquatic and terrestrial biodiversity due to its unprecedented use in aquaculture, livestock, and human disease prevention. The influx of tetracycline may annihilate the microbial ecology structure in the environment and pose a severe threat to humans by disturbing the food chain. Although significant research data are available in the literature on various aspects of tetracycline, including detection techniques, degradation mechanisms, degradation products, and policy statements to curtail the issue, there is a scarcity of a report to compile the recent data in the literature for better analysis and comparison by the policymakers. To achieve this paucity in knowledge, the current study aims at collecting data on the available degradation strategies, mechanisms involved in biodegradable and non-biodegradable routes, the main factor affecting degradation strategies, compile novel detection techniques of tetracycline antibiotics in the environment, discuss antibiotic resistance genes and their potential role in degradation. Finally, limitations in the current bioremediation techniques and the future prospects are discussed with pointers for the decision-makers for a safer environment.

A sensitive electrochemical detection of metronidazole in synthetic serum and urine samples using low-cost screen-printed electrodes modified with reduced graphene oxide and C60

Monitoring the concentration of antibiotics in body fluids is essential to optimizing the therapy and minimizing the risk of bacteria resistance, which can be made with electrochemical sensors tailored with appropriate materials. In this paper, we report on sensors made with screen-printed electrodes (SPE) coated with fullerene (C60), reduced graphene oxide (rGO) and Nafion (NF) (C60-rGO-NF/SPE) to determine the antibiotic metronidazole (MTZ). Under optimized conditions, the C60-rGO-NF/SPE sensor exhibited a linear response in square wave voltammetry for MTZ concentrations from 2.5 × 10-7 to 34 × 10-6 mol/L, with a detection limit of 2.1 × 10-7 mol/L. This sensor was also capable of detecting MTZ in serum and urine, with recovery between 94% and 100%, which are similar to those of the standard chromatographic method (HPLC-UV). Because the C60-rGO-NF/SPE sensor is amenable to mass production and allows for MTZ determination with simple principles of detection, it fulfills the requirements of therapeutic drug monitoring programs.

Emerging Electrochemical Sensors for Real-Time Detection of Tetracyclines in Milk

Antimicrobial drug residues in food are strictly controlled and monitored by national laws in most territories. Tetracyclines are a major broad-spectrum antibiotic class, active against a wide range of Gram-positive and Gram-negative bacteria, and they are the leading choice for the treatment of many conditions in veterinary medicine in recent years. In dairy farms, milk from cows being treated with antibiotic drugs, such as tetracyclines, is considered unfit for human consumption. Contamination of the farm bulk tank with milk containing these residues presents a threat to confidence of supply and results in financial losses to farmers and dairy. Real-time monitoring of milk production for antimicrobial residues could reduce this risk and help to minimise the release of residues into the environment where they can cause reservoirs of antimicrobial resistance. In this article, we review the existing literature for the detection of tetracyclines in cow's milk. Firstly, the complex nature of the milk matrix is described, and the test strategies in commercial use are outlined. Following this, emerging biosensors in the low-cost biosensors field are contrasted against each other, focusing upon electrochemical biosensors. Existing commercial tests that identify antimicrobial residues within milk are largely limited to beta-lactam detection, or non-specific detection of microbial inhibition, with tests specific to tetracycline residues less prevalent. Herein, we review a number of emerging electrochemical biosensor detection strategies for tetracyclines, which have the potential to close this gap and address the industry challenges associated with existing tests.

Advances in Electrochemical and Acoustic Aptamer-Based Biosensors and Immunosensors in Diagnostics of Leukemia

Early diagnostics of leukemia is crucial for successful therapy of this disease. Therefore, development of rapid, sensitive, and easy-to-use methods for detection of this disease is of increased interest. Biosensor technology is challenged for this purpose. This review includes a brief description of the methods used in current clinical diagnostics of leukemia and provides recent achievements in sensor technology based on immuno- and DNA aptamer-based electrochemical and acoustic biosensors. The comparative analysis of immuno- and aptamer-based sensors shows a significant advantage of DNA aptasensors over immunosensors in the detection of cancer cells. The acoustic technique is of comparable sensitivity with those based on electrochemical methods; moreover, it is label-free and provides straightforward evaluation of the signal. Several examples of sensor development are provided and discussed.

Pharma-molecule Transport across Bacterial Membranes: Detection and Quantification Approaches by Electrochemistry and Bioanalytical Methods

Antibiotic resistance is a significant challenge encountered by healthcare systems on a global scale. Knowledge about membrane transport of antibiotics and other pharmacologically relevant molecules in bacteria is crucial towards understanding and overcoming antibiotic resistance, as drug resistance often depends on drug transport. This comprehensive literature review discusses the detection and quantification of membrane transport of pharma-molecules in bacteria and highlights the importance of molecule transport to antibiotic resistance. This review emphasizes electrochemical and electrophysiological methods of detection and quantification. The results of this literature review reveal a substantial diversity in methods and types of quantitative information collected.

Development of a pH-dependent homogeneous liquid-liquid extraction by cold-induced phase separation in acetonitrile/water mixtures for determination of quinolone residues in animal-derived foods

A simple extraction procedure coupled with liquid chromatography-Q Orbitrap high resolution mass spectrometry (LC-Q Orbitrap HRMS) for the determination of 19 quinolones in animal-derived foods (pork, fish, egg and milk) has been developed. Sample preparation is based on homogeneous liquid-liquid extraction at pH > 9 using water-miscible acetonitrile with cold-induced phase separation. The procedure allowed one-step enrichment and cleanup of all the 19 quinolones with different logP properties to lower aqueous phase, which eliminated the process of preconcentration and re-dissolution for sample solution. Furthermore, an adsorption phenomenon was observed between conventional borosilicate glass injection vials and most of quinolones. In detection analysis, a scheduled variable full scan strategy was performed to improve detection performance in Q Orbitrap HRMS. Under optimal conditions, a superior limit of quantitation (0.028-0.192 μg/kg) in animal-derived foods was achieved using this proposed method. Lastly, this method was validated and applied successfully in real samples.

Metal Nanoparticle and Quantum Dot Tags for Signal Amplification in Electrochemical Immunosensors for Biomarker Detection

With the increasing importance of healthcare and clinical diagnosis, as well as the growing demand for highly sensitive analytical instruments, immunosensors have received considerable attention. In this review, electrochemical immunosensor signal amplification strategies using metal nanoparticles (MNPs) and quantum dots (Qdots) as tags are overviewed, focusing on recent developments in the ultrasensitive detection of biomarkers. MNPs and Qdots can be used separately or in combination with other nanostructures, while performing the function of nanocarriers, electroactive labels, or catalysts. Thus, different functions of MNPs and Qdots as well as recent advances in electrochemical signal amplification are discussed. Additionally, the methods most often used for antibody immobilization on nanoparticles, immunoassay formats, and electrochemical methods for indirect biomarker detection are overviewed.

A robust electrochemical immunosensor based on core-shell nanostructured silica-coated silver for cancer (carcinoembryonic-antigen-CEA) diagnosis

This work addresses the fabrication of an efficient, novel, and economically viable immunosensing armamentarium that will detect the carcinoembryonic antigen (CEA) typically associated with solid tumors (sarcomas, carcinomas, and lymphomas) and is used as a clinical tumor marker for all these malignancies. We synthesized silver nanoparticles by single-step chemical reduction and coated with silica using a modified Stober method to fabricate silica-coated silver core-shell nanoparticles. The morphologies, structure, and size of the nanoparticles were characterized by Transmission Electron Microscopy (TEM), UV-Visible spectroscopy, X-ray diffraction (XRD), Raman spectroscopy, Fourier Transform Infra-Red Spectroscopy (FTIR), and Dynamic Light Scattering (DLS), respectively. The results indicated that the average size of Ag nanoparticles and silica-coated Ag nanoparticles is 50 nm and 80 nm, respectively. Our TEM results indicate that the silica-shell uniformly encapsulates silver core particles. Further, a disposable electrochemical immunosensor for carcinoembryonic antigen (CEA) was proposed based on the antigen immobilized in a silica-coated silver core-shell nanoparticle film on the surface of an indium-tin-oxide (ITO) flat substrate. The morphological characteristics of the constructed biosensor were observed by scanning electron microscopy (SEM) and electrochemical methods. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were employed for the characterization of the proposed bioelectrode. The cyclic voltammogram appears to be more irreversible on silica coated silver core-shell nanoparticles. It is found that the fabricated immunosensor shows fast potentiometric response under the optimized conditions. The CEA could be determined in the linear range from 0.5 to 10 ng mL-1 with a detection limit of 0.01 ng mL-1 using the interface. The developed flat substrate of ITO for CEA detection (the model reagent) is a potentially promising immunosensing system, manifests good stability, and allows batch fabrication because of its economic feasibility.

Aqueous media ultra-sensitive detection of antibiotics via highly stable luminescent 3D Cadmium-based MOF

A novel Cd-based MOF shows high sensitivity (Ksv ∼ 106 M−1) and selectivity (μM level) towards antibiotics was presented.

A review on graphene-based electrochemical sensor for mycotoxins detection

This work focuses on the study of nanomaterial-based sensors for mycotoxins detection. Due to their adverse effects on humans and animals, mycotoxins are heavily regulated, and the foodstuff and feed stocks with a high probability of being contaminated are often analyzed. In this context, the recent developments in graphene-based electrochemical sensors for mycotoxins detection were examined. The mycotoxins' toxicity implications on their detection and the development of diverse recognition elements are described considering the current challenges and limitations.

Investigation of a Truncated Aptamer for Ofloxacin Detection Using a Rapid FRET-Based Apta-Assay

In this work, we describe the use of a new truncated aptamer for the determination of ofloxacin (OFL), being a principal quinolone commonly used in both human and animal healthcare. Since the affinity of a 72-mer ssDNA sequence has been previously described without further investigations, this paper demonstrates the first computational prediction of the binding motif between this aptamer and OFL through in silico molecular docking studies. Besides, we suggest the application of the characterized recognition mechanism in a simple FRET (Förster Resonance Energy Transfer) pattern for the rapid aptasensing of the quinolone of interest. Accordingly, our approach harnesses the fluorescence quenching of the fluorescein-tagged aptamer (FAM-APT) induced by its partial hybridization to a tetramethyl rhodamine-labelled complementary ssDNA (TAMRA-cDNA). In such a structure, dye labels brought into close proximity act as a FRET pair. Upon ofloxacin addition, an affinity competition occurs to form a more stable FAM-APT/OFL complex, thus unquenching the FAM-APT signal. Interestingly, the recovered fluorescence intensity was found to correlate well with the antibiotic's concentrations in the range of 0.2-200 μM in HEPES buffer, with a linear response that ranged between 0.2 and 20 μM. The rapid apta-assay achieved limits of detection and quantification of 0.12 and 0.40 μM, respectively. The truncated aptamer has also shown an improved specificity toward OFL than other quinolones, compared to the original full-length aptamer described in previous works. Finally, the practical application of the developed apta-assay was successfully confirmed to detect OFL quinolone in spiked milk samples, with satisfactory recoveries ranging between 97.4% and 111.4%.

Ultrasensitive detection of pathogenic viruses with electrochemical biosensor: State of the art

Last few decades, viruses are a real menace to human safety. Therefore, the rapid identification of viruses should be one of the best ways to prevent an outbreak and important implications for medical healthcare. The recent outbreak of coronavirus disease (COVID-19) is an infectious disease caused by a newly discovered coronavirus which belongs to the single-stranded, positive-strand RNA viruses. The pandemic dimension spread of COVID-19 poses a severe threat to the health and lives of seven billion people worldwide. There is a growing urgency worldwide to establish a point-of-care device for the rapid detection of COVID-19 to prevent subsequent secondary spread. Therefore, the need for sensitive, selective, and rapid diagnostic devices plays a vital role in selecting appropriate treatments and to prevent the epidemics. During the last decade, electrochemical biosensors have emerged as reliable analytical devices and represent a new promising tool for the detection of different pathogenic viruses. This review summarizes the state of the art of different virus detection with currently available electrochemical detection methods. Moreover, this review discusses different fabrication techniques, detection principles, and applications of various virus biosensors. Future research also looks at the use of electrochemical biosensors regarding a potential detection kit for the rapid identification of the COVID-19.

Determination and Identification of Antibiotic Drugs and Bacterial Strains in Biological Samples

Antibiotics were initially natural substances. However, nowadays, they also include synthetic drugs, which show their activity against bacteria, killing or inhibiting their growth and division. Thanks to these properties, many antibiotics have quickly found practical application in the fight against infectious diseases such as tuberculosis, syphilis, gastrointestinal infections, pneumonia, bronchitis, meningitis and septicemia. Antibiotic resistance is currently a detrimental problem; therefore, in addition to the improvement of antibiotic therapy, attention should also be paid to active metabolites in the body, which may play an important role in exacerbating the existing problem. Taking into account the clinical, cognitive and diagnostic purposes of drug monitoring, it is important to select an appropriate analytical method that meets all the requirements. The detection and identification of the microorganism responsible for the infection is also an essential factor in the implementation of appropriate antibiotic therapy. In recent years, clinical microbiology laboratories have experienced revolutionary changes in the way microorganisms are identified. The MALDI-TOF MS technique may be interesting, especially in some areas where a quick analysis is required, as is the case with clinical microbiology. This method is not targeted, which means that no prior knowledge of the infectious agent is required, since identification is based on a database match.