Recent advances in nanomaterial-based electrochemical detection of antibiotics: Challenges and future perspectives

Electrochemical analysis of anticancer and antibiotic drugs in water and biological specimens

The increasing prevalence of pharmaceuticals in water and complex matrices necessitates accurate measurement and monitoring of their environmental contamination levels. This is crucial not only for environmental conservation but also for comprehending the intricate mechanisms involved and developing more effective treatment approaches. In this context, electrochemical techniques show significant potential for the detection of pharmaceuticals across various matrices. Specifically, voltammetry is advantageous due to its rapid, straightforward, and cost-effective nature, allowing for the simultaneous analysis of multiple anticancer and antibiotic drugs. By utilizing nanomaterial-modified electrochemical sensors, the sensitivity and selectivity of detection methods can be significantly improved. The small size and customizable properties of nanomaterials enable these sensors to identify trace amounts of drugs in diverse samples. However, challenges persist in achieving reliable and accurate electrochemical monitoring of drugs in water and biological samples. Biofluids such as saliva, urine, and blood/serum, along with environmental samples from lakes and rivers, often contain numerous interfering substances that can diminish analyte signals. This review examines electrochemical methods and their potential applications for detecting pharmaceuticals and their metabolites, while also addressing the mechanisms of action and harmful effects of these drugs on both ecosystems and human health. Recent developments in electrochemical sensors utilizing nanomaterials for the detection of health-threatening pharmaceutical contaminants are examined, providing important insights into their underlying mechanisms. The emphasis is placed on the detection of anticancer agents and antibiotics, which relies on the electrocatalytic properties of the sensor materials. Additionally, discussions on density functional theory studies are included, along with an exploration of the emerging challenges and future directions in this area, aimed at enhancing readers' comprehension of the field and underscoring the necessary actions for a sustainable future.

A facile synthesis of iron oxide nanoparticles as a nano-sensor to detect levofloxacin and ciprofloxacin in human blood and evaluation of their biological activities

A rapid synthesis of a pH-stable magnetic nano-sensor (iron oxide nanoparticles, Fe-NPs, ∼2.6 nm) encapsulated with 3-aminobenzoic acid (3-ABA) was achieved. 3-ABA was prepared for the first time through the reduction of 3-nitrobenzoic acid (3-NBA) in the presence of HCl and tin. Electron-impact mass spectrometry (EIMS), Fourier-transform infrared (FTIR), nuclear magnetic resonance (NMR), ultraviolet visible (UV) spectroscopy and atomic force microscopy (AFM) were used for characterization. Ten drugs, namely, ciprofloxacin (CPF), levocetirizine (LCT), levofloxacin (LVF), sulbactam sodium (SBS), ephedrine (EPH), thymine (THM), sertraline (SRT), pyridoxine (PRX), cefotaxime (CFX) and ceftriaxone (CFT) were screened with Fe-NPs. A pronounced hypsochromic shift was observed for levofloxacin and ciprofloxacin, proving that 3-ABA-coated Fe-NPs were an efficient nano-sensor for levofloxacin and ciprofloxacin up to the limit of 0.5 and 0.7 μM, respectively. The stoichiometry of the complexes was conclusively determined as 1 : 1 using Job's plot analysis. Furthermore, the drugs were successfully detected in real samples, including tap water, well water, and human blood. Moreover, the antioxidant activity, urease and lipoxygenase inhibitory potential of these nanoparticles were evaluated, exhibiting promising antioxidant potential.

Graphene-based electrochemical sensors for antibiotics: sensing theories, synthetic methods, and on-site monitoring applications

Owing to the extensive use of antibiotics for treating infectious diseases in livestock and humans, the resulting residual antibiotics are a burden to the ecosystem and human health. Hence, for human health and ecological safety, it is critical to determine the residual antibiotics with accuracy and convenience. Graphene-based electrochemical sensors are an effective tool to detect residual antibiotics owing to their advantages, such as, high sensitivity, simplicity, and time efficiency. In this work, we comprehensively summarize the recent advances in graphene-based electrochemical sensors used for detecting antibiotics, including modifiers for electrode fabrication, theoretical elaboration of electrochemical sensing mechanisms, and practical applications of portable electrochemical platforms for the on-site monitoring of antibiotics. It is anticipated that the current review will be a valuable reference for comprehensively comprehending graphene-based electrochemical sensors and further promoting their applications in the fields of healthcare, environmental protection, and food safety.

Metal Organic Frameworks Based Wearable and Point-of-Care Electrochemical Sensors for Healthcare Monitoring

The modern healthcare system strives to provide patients with more comfortable and less invasive experiences, focusing on noninvasive and painless diagnostic and treatment methods. A key priority is the early diagnosis of life-threatening diseases, which can significantly improve patient outcomes by enabling treatment at earlier stages. While most patients must undergo diagnostic procedures before beginning treatment, many existing methods are invasive, time-consuming, and inconvenient. To address these challenges, electrochemical-based wearable and point-of-care (PoC) sensing devices have emerged, playing a crucial role in the noninvasive, continuous, periodic, and remote monitoring of key biomarkers. Due to their numerous advantages, several wearable and PoC devices have been developed. In this focused review, we explore the advancements in metal-organic frameworks (MOFs)-based wearable and PoC devices. MOFs are porous crystalline materials that are cost-effective, biocompatible, and can be synthesized sustainably on a large scale, making them promising candidates for sensor development. However, research on MOF-based wearable and PoC sensors remains limited, and no comprehensive review has yet to synthesize the existing knowledge in this area. This review aims to fill that gap by emphasizing the design of materials, fabrication methodologies, sensing mechanisms, device construction, and real-world applicability of these sensors. Additionally, we underscore the importance and potential of MOF-based wearable and PoC sensors for advancing healthcare technologies. In conclusion, this review sheds light on the current state of the art, the challenges faced, and the opportunities ahead in MOF-based wearable and PoC sensing technologies.

A universal optical aptasensor for antibiotics determination based on a new high-efficiency Förster resonance energy transfer pair

A novel "turn-on" aptasensor for kanamycin (Kana) detection based on a new Förster resonance energy transfer (FRET) pair is reported. A new organic small molecule was employed as a high-efficiency quencher for fluorophore. Based on specific interactions between ssDNA and the quencher, an ingenious and amplified strategy was designed. In the absence of the target, the fluorescence of the fluorophore labeled at the end of the aptamer was quenched. After the binding of the aptamer to the target, the fluorescence was recovered and amplified. The proposed aptasensor showed high specificity, selectivity, and stability in complicated systems. With the P3-based strategy, the limit of detection for Kana is estimated to be 10 nM, which is much lower than the maximum allowable concentration in milk. The recoveries of spiked Kana in milk were in the range 99.8 ~ 105.3% (n = 3). Fortunately, this novel method can be easily extended to other antibiotics such as tobramycin by simply replacing the aptamer, showing great potential as a universal platform for selective, sensitive, and rapid detection of hazardous analytes in food samples.

Cu2MoS4 Nanocatalyst-Based Electrochemical Sensor for Ofloxacin Electro-Oxidation: Delineating the Combined Roles of Crystallinity and Morphology on the Analytical Performance

In this study, we demonstrate the influence of crystallinity and morphology on the analytical performance of various Cu2MoS4 (CMS) nanocatalysts-based electrochemical sensors for the high-efficiency detection of Ofloxacin (OFX) antibiotic. The electrochemical kinetics parameters including peak current response (ΔIp), peak-to-peak separation (ΔEp), electrochemically active surface area (ECSA), electron-transfer resistance (Rct), were obtained through the electrochemical analyses, which indicate the single-crystalline nature of CMS nanomaterials (NMs) is beneficial for enhanced electron-transfer kinetics. The morphological features and the electrochemical results for OFX detection substantiate that by tuning the tube-like to plate-like structures of the CMS NMs, it might noticeably enhance multiple adsorption sites and more intrinsic active catalytic sites due to the diffusion of analytes into the interstitial spaces between CMS nanoplates. As results, highly single-crystalline and plate-shaped morphology structures of CMS NMs would significantly enhance the electrocatalytic OFX oxidation in terms of onset potential (Eonset), Tafel slope, catalytic rate constant (kcat), and adsorption capacity (Γ). The CMS NMs-based electrochemical sensing platform showed excellent analytical performance toward the OFX detection with two ultra-wide linear detection concentration ranges from 0.25-100 and 100-1000 μM, a low detection limit of 0.058 μM, and an excellent electrochemical sensitivity (0.743 μA μM-1 cm-2).

Strategies to Enrich Electrochemical Sensing Data with Analytical Relevance for Machine Learning Applications: A Focused Review

In this review, recent advances regarding the integration of machine learning into electrochemical analysis are overviewed, focusing on the strategies to increase the analytical context of electrochemical data for enhanced machine learning applications. While information-rich electrochemical data offer great potential for machine learning applications, limitations arise when sensors struggle to identify or quantitatively detect target substances in a complex matrix of non-target substances. Advanced machine learning techniques are crucial, but equally important is the development of methods to ensure that electrochemical systems can generate data with reasonable variations across different targets or the different concentrations of a single target. We discuss five strategies developed for building such electrochemical systems, employed in the steps of preparing sensing electrodes, recording signals, and analyzing data. In addition, we explore approaches for acquiring and augmenting the datasets used to train and validate machine learning models. Through these insights, we aim to inspire researchers to fully leverage the potential of machine learning in electroanalytical science.

Electrochemical sensing mechanisms of neonicotinoid pesticides and recent progress in utilizing functional materials for electrochemical detection platforms

The excessive residue of neonicotinoid pesticides in the environment and food poses a severe threat to human health, necessitating the urgent development of a sensitive and efficient method for detecting trace amounts of these pesticides. Electrochemical sensors, characterized by their simplicity of operation, rapid response, low cost, strong selectivity, and high feasibility, have garnered significant attention for their immense potential in swiftly detecting trace target molecules. The detection capability of electrochemical sensors primarily relies on the catalytic activity of electrode materials towards the target analyte, efficient loading of biomolecular functionalities, and the effective conversion of interactions between the target analyte and its receptor into electrical signals. Electrode materials with superior performance play a crucial role in enhancing the detection capability of electrochemical sensors. With the continuous advancement of nanotechnology, particularly the widespread application of novel functional materials, there is paramount significance in broadening the applicability and expanding the detection range of pesticide sensors. This comprehensive review encapsulates the electrochemical detection mechanisms of neonicotinoid pesticides, providing detailed insights into the outstanding roles, advantages, and limitations of functional materials such as carbon-based materials, metal-organic framework materials, supramolecular materials, metal-based nanomaterials, as well as molecular imprinted materials, antibodies/antigens, and aptamers as molecular recognition elements in the construction of electrochemical sensors for neonicotinoid pesticides. Furthermore, prospects and challenges facing various electrochemical sensors based on functional materials for neonicotinoid pesticides are discussed, providing valuable insights for the future development and application of biosensors for simplified on-site detection of agricultural residues.

State-of-the-art nanosensors and kits for the detection of antibiotic residues in milk and dairy products

Antibiotic resistance is increasingly seen as a future concern, but antibiotics are still commonly used in animals, leading to their accumulation in humans through the food chain and posing health risks. The development of nanomaterials has opened up possibilities for creating new sensing strategies to detect antibiotic residues, resulting in the emergence of innovative nanobiosensors with different benefits like rapidity, simplicity, accuracy, sensitivity, specificity, and precision. Therefore, this comprehensive review provides pertinent and current insights into nanomaterials-based electrochemical/optical sensors for the detection of antibitic residues (ANBr) across milk and dairy products. Here, we first discuss the commonly used ANBs in real products, the significance of ANBr, and also their binding/biological properties. Then, we provide an overview of the role of using different nanomaterials on the development of advanced nanobiosensors like fluorescence-based, colorimetric, surface-enhanced Raman scattering, surface plasmon resonance, and several important electrochemical nanobiosensors relying on different kinds of electrodes. The enhancement of ANB electrochemical behavior for detection is also outlined, along with a concise overview of the utilization of (bio)recognition units. Ultimately, this paper offers a perspective on the future concepts of this research field and commercialized nanomaterial-based sensors to help upgrade the sensing techniques for ANBr in dairy products.

Non-Enzymatic Glucose Sensors Composed of Polyaniline Nanofibers with High Electrochemical Performance

The measurement of glucose concentration is a fundamental daily care for diabetes patients, and therefore, its detection with accuracy is of prime importance in the field of health care. In this study, the fabrication of an electrochemical sensor for glucose sensing was successfully designed. The electrode material was fabricated using polyaniline and systematically characterized using scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and UV-visible spectroscopy. The polyaniline nanofiber-modified electrode showed excellent detection ability for glucose with a linear range of 10 μM to 1 mM and a detection limit of 10.6 μM. The stability of the same electrode was tested for 7 days. The electrode shows high sensitivity for glucose detection in the presence of interferences. The polyaniline-modified electrode does not affect the presence of interferences and has a low detection limit. It is also cost-effective and does not require complex sample preparation steps. This makes it a potential tool for glucose detection in pharmacy and medical diagnostics.

Understanding Antibiotic Detection with Fluorescence Quantum Dots: A Review

The utilization of fluorescent quantum dots (FL QDs) has gained significant traction in the realm of antibiotic detection, owing to their exceptional FL properties and versatility. Various types of QDs have been tailored to exhibit superior FL characteristics, employing diverse capping agents such as metals, surfactants, polymers, and biomass to protect and stabilize their surfaces. In their evolution, FL QDs have demonstrated both "turn-off" and "turn-on" mechanisms in response to the presence of analytes, offering promising avenues for biosensing applications. This review article provides a comprehensive overview of the recent advancements in antibiotic detection utilizing FL QDs as biosensors. It encompasses an extensive examination of different types of FL QDs, including carbon, metal, and core-shell QDs, deployed for the detection of antibiotics. Furthermore, the synthesis methods employed for the fabrication of various FL QDs are elucidated, shedding light on the diverse approaches adopted in their preparation. Moreover, this review delves into the intricate sensing mechanisms underlying FL QDs-based antibiotic detection. Various mechanisms, such as photoinduced electron transfer, electron transfer, charge transfer, Forster resonance energy transfer, static quenching, dynamic quenching, inner filter effect, hydrogen bonding, and aggregation-induced emission, are discussed in detail. These mechanisms provide a robust scientific rationale for the detection of antibiotics using FL QDs, showcasing their potential for sensitive and selective sensing applications. Finally, the review addresses current challenges and offers perspectives on the future improvement of FL QDs in sensing applications. Insights into overcoming existing limitations and harnessing emerging technologies are provided, charting a course for the continued advancement of FL QDs-based biosensing platforms in the field of antibiotic detection.

Highly electroactive Co-ZnO/GO nanocomposite: Electrochemical sensing platform for oxytetracycline determination

Antimicrobial residues in animal-derived foods have become a major source of concern around the world. Oxytetracycline (OTC), one of these antibiotics that belongs to the tetracycline family should be detected in these matrices. Nanostructured metal oxides have attracted a lot of scientific attention due to their special characteristics that can be exploited for creating innovative nanodevices. Therefore, in the present study, we report the fabrication of cobalt-doped ZnO/GO nanocomposites for OTC sensors using a simple and environmentally friendly method that does not require toxic solvents. Contact angle measurements, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and UV-Vis were used to confirm the successful fabrication of the Co-ZnO/GO nanocomposite and to determine the surface area, Structural, morphological features, chemical composition and purity of the nanocomposite. The electrochemical and electrocatalytic properties were recorded using cyclic voltammetry (CV), electrochemical impedance spectroscopy, and differential pulse voltammetry (DPV). Optimizing parameters such as scan rate, pH value, deposition time, and deposition potential, we achieve a wide linear concentration range from 10-12 M to 10-7 M, with an impressive detection limit of 1.6 10-13 M.Notably, our sensor exhibits remarkable selectivity, demonstrating its usefulness for the detection of oxytetracycline traces in real milk samples. These results emphasize the novelty and practical significance of our work and provide a promising avenue for the development of sensitive and selective electrochemical sensing platforms in various fields.

Recent trends and advancement in metal oxide nanoparticles for the degradation of dyes: synthesis, mechanism, types and its application

Synthetic dyes play a crucial role in our daily lives, especially in clothing, leather accessories, and furniture manufacturing. Unfortunately, these potentially carcinogenic substances are significantly impacting our water systems due to their widespread use. Dyes from various sources pose a serious environmental threat owing to their persistence and toxicity. Regulations underscore the urgency in addressing this problem. In response to this challenge, metal oxide nanoparticles such as titanium dioxide (TiO2), zinc oxide (ZnO), and iron oxide (Fe3O4) have emerged as intriguing options for dye degradation due to their unique characteristics and production methods. This paper aims to explore the types of nanoparticles suitable for dye degradation, various synthesis methods, and the properties of nanoparticles. The study elaborates on the photocatalytic and adsorption-desorption activities of metal oxide nanoparticles, elucidating their role in dye degradation and their application potential. Factors influencing degradation, including nanoparticle properties and environmental conditions, are discussed. Furthermore, the paper provides relevant case studies, practical applications in water treatment, and effluent treatment specifically in the textile sector. Challenges such as agglomeration, toxicity concerns, and cost-effectiveness are acknowledged. Future advancements in nanomaterial synthesis, their integration with other materials, and their impact on environmental regulations are potential areas for development. In conclusion, metal oxide nanoparticles possess immense potential in reducing dye pollution, and further research and development are essential to define their role in long-term environmental management.

A trivalent aptasensor by using DNA tetrahedron as scaffold for label-free determination of antibiotics

Owing to advantage in high sensitivity and fast response, aptamer based electrochemical biosensors have attracted much more attention. However, inappropriate interfacial engineering strategy leads to poor recognition performance, which ascribe to the following factors of immobilized oligonucleotide strand including steric hindrance, interchain entanglement, and unfavorable conformation. In this work, we proposed a DNA tetrahedron based diblock aptamer immobilized strategy for the construction of label-free electrochemical biosensor. The diblock aptamer sequence is composite of T-rich anchor domain and recognition domain, where T-rich domain enabling anchored on the edge of DNA tetrahedron via Hoogsteen hydrogen bond at neutral condition. The DNA tetrahedron scaffold offers an appropriate lateral space for target recognition of diblock aptamer. More importantly, this trivalent aptamer recognition interface can be regenerated by simply adjusting the pH environment to alkaline, resulting in the dissociation of diblock aptamer. Under the optimum condition, proposed electrochemical aptasensor manifested a satisfied sensitivity for aminoglycosides antibiotic, kanamycin with a limit of detection of 0.69 nM, which is 45-fold lower than traditional Au-S immobilization strategy. Moreover, the proposed aptasensor had also successfully been extended to ampicillin detection by changing the sequence of recognition domain in diblock aptamer. This work paves a new way for the rational design of aptamer-based electrochemical sensor.

Electrochemical detection of sulfanilamide using tannic acid exfoliated MoS2 nanosheets combined with reduced graphene oxide/graphite

Sulfonamides are a family of synthetic drugs with a broad-spectrum of antimicrobial activity. Like other antimicrobials, they have been found in aquatic environments, making their detection important. Herein, an electrochemical sensor was designed using tannic acid exfoliated few-layered MoS2 sheets, which were combined with a mixture of reduced graphene oxide (rGO) and graphite flakes (G). The rGO/G was formed using electrodeposition, by cycling from -0.5 to -1.5 V in an acidified sulfate solution with well dispersed GO and G. The exfoliated MoS2 sheets were drop cast over the wrinkled rGO/G surface to form the final sensor, GCE/rGO/G/ta-MoS2. The mixture of rGO/G was superior to pure rGO in formulating the sensor. The fabricated sensor exhibited an extended linear range from 0.1 to 566 μM, with a LOD of 86 nM, with good selectivity in the presence of various salts found in water and structurally related drugs from the sulfonamide family. The sensor showed very good reproducibility with the RSD at 0.48 %, repeatability and acceptable long term stability over a 10-day period. Good recovery from both tap and river water was achieved, with recovery ranging from 90.4 to 98.9 % for tap water and from 83.5 to 94.4 % for real river water samples.

Metal-Organic Frameworks Based Sensor Platforms for Rapid Detection of Contaminants in Wastewater

Metal-organic frameworks (MOFs) are a type of multifunctional material with organic-inorganic doped metal complexes that have a lot of unsaturated metal sites and a consistent network structure. MOFs work has great performance for enhancing the mass transfer, signal, and sensitivity as well as analyte enrichment. This study highlights the recent advancements of MOFs-based sensors for pollutant detection in a water environment and summarizes the effect of various synthetic materials on the performance of MOFs-based sensors. The related challenges and optimization techniques have been discussed. Then the research results of various MOFs sensors in the detection of wastewater pollutants are analyzed. Finally, the challenges facing MOFs-based water sensor development and the outlook for future research are discussed.

Multi-modal nanoprobe-enabled biosensing platforms: a critical review

Nanomaterials show great potential for applications in biosensing due to their unique physical, chemical, and biological properties. However, the single-modal signal sensing mechanism greatly limits the development of single-modal nanoprobes and their related sensors. Multi-modal nanoprobes can realize the output of fluorescence, colorimetric, electrochemical, and magnetic signals through composite nanomaterials, which can effectively compensate for the defects of single-modal nanoprobes. Following the multi-modal nanoprobes, multi-modal biosensors break through the performance limitation of the current single-modal signal and realize multi-modal signal reading. Herein, the current status and classification of multi-modal nanoprobes are provided. Moreover, the multi-modal signal sensing mechanisms and the working principle of multi-modal biosensing platforms are discussed in detail. We also focus on the applications in pharmaceutical detection, food and environmental fields. Finally, we highlight this field's challenges and development prospects to create potential enlightenment.

Natural needle microstructure-based immunochromatographic assay for sensitively detecting streptomycin in food products

Immunochromatographic assays (ICAs) are famous as the point of care test (POCT) technology against food fraud for antibiotics detection. However, the poor sensitivity, stability and the monoclonal antibodies (mAbs)-depended signals limited their further applications. Here, inspired by the vivid color display and functionalization of natural pigments, we developed natural edible pigment-derived needle microstructure (NNMS) as signal tracers by simple crosslinking of alizarin and formaldehyde, allowing high color rendering ability, significant water dispersibility and antibody enrichment. Particularly, immune-network technology was introduced to achieve the simultaneous promotion of colorimetric signal and sensitivity and avoid visual errors in ICA. As a result, the prepared eco-friendly and sustainable NNMS-ICA showed satisfactory performance (LOD was 0.56 ng mL-1), specificity and probe stability (CV was 1.90 %). Furthermore, the NNMS-ICA was successfully applied in food samples (milk and honey) with total recoveries at 91.00-118.82 %.

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.

Emerging Trends in nanostructured materials-coated screen printed electrodes for the electrochemical detection of hazardous heavy metals in environmental matrices

Heavy metal ions (HMIs) have become a significant contaminant in recent years. The increase in heavy metal pollution is a serious situation, requiring progressively robust, fast sensing, highly sensitive, and suitable techniques for heavy metal detection. Compared to other classical analytical methods, electroanalytical techniques, especially stripping voltammetric techniques with modified screen-printed electrodes (SPEs), have several advantages, such as fast sensing, great sensitivity, specificity, and long-time stability. Therefore, these techniques are more suitable for HMI detection. In this review, the nanostructured materials used to coat SPEs for the electrochemical determination of HMI are summarized. Additionally, the electrode fabrication method, modification steps, and electroanalytical study of these materials are systematically discussed. Hence, this review will support the researchers in precisely evaluating the electrochemical HMIs detection through highly sensitive stripping voltammetric techniques using SPE modified with nanostructured carbon and their allotropes, metal, metal oxides and their nanocomposites as sensor materials. Moreover, modified electrodes real time detection of HMIs in different food and environmental samples were briefly discussed.

AIE Ligand-Based Luminescent Ln-MOFs for Rapid and Selective Sensing of Tetracycline

The design of highly stable and dual-emission lanthanide metal-organic frameworks (Ln-MOFs) is promising for practical chemical sensor applications. Rational design and synthesis of photoresponsive organic ligands provide a feasible approach to achieving highly fluorescent dual-emission Ln-MOFs. In this study, a tetraphenylpyrazine-based AIE ligand, H4L, was synthesized and combined with lanthanide ions (including Sm3+, Eu3+, Gd3+, and Tb3+) to fabricate a series of Ln-MOFs named Ln-L. The single-crystal analysis revealed that all Ln-L belonged to the tetragonal space group P4212 and featured a 2-fold interpenetrated 3D structure. Leveraging rational design, Eu-L exhibited a sensitive response to tetracycline, making it a promising fluorescence sensor for tetracycline detection. The experiments demonstrated that Eu-L could rapidly and quantitatively detect tetracycline and its analogs within 30 s. The lowest detection limits for tetracycline, oxytetracycline, and chlortetracycline were 0.43, 0.92, and 0.81 μM, respectively. Additionally, the probe displayed excellent reusability and exceptional selectivity. A plausible sensing mechanism was proposed, supported by both experimental and theoretical analyses. Furthermore, the study discovered that on-site and real-time determination of TCs in aqueous solutions could be achieved by using luminescence test papers and composite films derived from Eu-L.

A Sensitive Fluorescence Sensor for Tetracycline Determination Based on Adenine Thymine-Rich Single-Stranded DNA-Templated Copper Nanoclusters

A sensitive fluorescent sensor has been developed for the determination of tetracycline (TC) using adenine thymine (AT)-rich single-stranded DNA (ssDNA) templated copper nanoclusters (CuNCs) as a fluorescent probe. Fluorescent ssDNA-CuNCs were synthesized by employing AT-rich ssDNA as templates and ascorbic acid as reducing agents through a facile one-step method. The as-prepared ssDNA-CuNCs exhibited strong fluorescence with a large Stokes shift (240 nm) and stable fluorescence emission. In the presence of TC, the fluorescent intensity of ssDNA-CuNCs was obviously decreased through the inner filter effect, due to the spectral overlapping between ssDNA-CuNCs and TC. Under the optimal conditions, the strategy exhibited sensitive detection of TC with a linear range from 2 nM to 30 μM and with a limit of detection of 0.5 nM. Furthermore, the sensor was successfully applied for the detection of TC in milk samples. Therefore, it provided a simple, rapid, and label-free fluorescent method for TC detection.

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.

Ultrasensitive levofloxacin electrochemical biosensor based on semiconducting covalent organic framework/poly-L-cysteine/triangular Ag nanoplates modified glassy carbon electrode

A novel electrochemical biosensor with excellent performance was fabricated for levofloxacin (LEV) detection, which adopted triangular Ag nanoplates (Tri-AgNP) confined in a poly-L-cysteine (poly-L-Cys) film and a semiconducting covalent organic framework (COF) as the electrochemical sensing material. The developed electrochemical sensor revealed excellent analytical properties because of its good electrical conductivity, fast electron transfer, and abundant bioactive site. Based on this, a linear relationship between the LEV concentration and the peak current response at 0.92 V was obtained under the optimal experimental conditions by differential pulse voltammetry (DPV), with a wide linear range of 0.05 to 600 μM and a low limit of detection (LOD) of 0.0061 μM. The prepared sensor also realized sensitive and accurate determination of LEV in human serum and urine samples by standard addition method, with satisfactory recoveries (97.1 to 104%) and a low relative standard deviation of less than 4.6%. These results indicated that the novel ternary system has a promising application in the development of electrochemical signal probe and electrochemical biosensing platform.

Design of NiS@Ni3S2/CdS heterostructure with intimate contact interface for sensitive photoelectrochemical detection of lincomycin

Owing to their internal electric field effect and abundant photo-induced carriers, photoactive heterostructured materials are considered a feasible approach to improve the sensitivity of a photoelectrochemical (PEC) sensor. Herein, a novel NiS@Ni₃S₂/CdS heterostructure composite is derived from Ni-loaded zeolitic imidazolate framework (Ni-ZIF). The PEC experiments showed the NiS@Ni₃S₂/CdS composite exhibits superior photocurrent response than NiS@Ni₃S₂ and CdS. This is attributed to the fact that the type II heterojunction of NiS@Ni₃S₂/CdS with a tightly connected interface reduces the transport distance of carriers and facilitates electron-hole separation. Next, using the NiS@Ni₃S₂/CdS modified electrode, an aptamer/glutaraldehyde/chitosan/NiS@Ni₃S₂/CdS/ITO PEC biosensor is developed, which exhibits excellent sensitivity for lincomycin (Lin) detection with a wide linear range (0.0001 ∼ 1.25 nM) and a low detection limit of 0.067 pM. The prepared sensor is further employed to monitor Lin in the actual milk. The results confirm that the prepared sensing electrode displays good selectivity, repeatability and stability.

Cost-effective protocol to produce 3D-printed electrochemical devices using a 3D pen and lab-made filaments to ciprofloxacin sensing

A novel conductive filament based on graphite (Gr) dispersed in polylactic acid polymer matrix (PLA) is described to produce 3D-electrochemical devices (Gr/PLA). This conductive filament was used to additively manufacture electrochemical sensors using the 3D pen. Thermogravimetric analysis confirmed that Gr was successfully incorporated into PLA, achieving a composite material (40:60% w/w, Gr and PLA, respectively), while Raman and scanning electron microscopy revealed the presence of defects and a high porosity on the electrode surface, which contributes to improved electrochemical performance. The 3D-printed Gr/PLA electrode provided a more favorable charge transfer (335 Ω) than the conventional glassy carbon (1277 Ω) and 3D-printed Proto-pasta® (3750 Ω) electrodes. As a proof of concept, the ciprofloxacin antibiotic, a species of multiple interest, was selected as a model molecule. Thus, a square wave voltammetry (SWV) method was proposed in the potential range + 0.9 to + 1.3 V (vs Ag|AgCl|KCl_(sat)), which provided a wide linear working range (2 to 32 µmol L^-1), 1.79 µmol L^-1 limit of detection (LOD), suitable precision (RSD < 7.9%), and recovery values from 94 to 109% when applied to pharmaceutical and milk samples. Additionally, the sensor is free from the interference of other antibiotics routinely employed in veterinary practices. This device is disposable, cost-effective, feasibly produced in financially limited laboratories, and consequently promising for evaluation of other antibiotic species in routine applications.

Aggregation-Induced Near-Infrared Emission and Electrochemiluminescence of an Iridium(III) Complex for Ampicillin Sodium Sensing

A new iridium(III) complex was synthesized and characterized. Its photophysical properties and aggregation-induced emission and electrochemiluminescence in the near-infrared range were studied. The large conjugated cyclometallic ligand 1,2-phenylbenzoquinoline (pbq) was selected to form the Ir-C bond with the metal iridium(III) center and provide near-infrared emission of the complex. The auxiliary ligand 4,4'-diamino-2,2'-bipyridine (dabpy) can form hydrogen bonds, which was beneficial for the generation of aggregation-induced emission. The complex was aggregated into small spherical nanoparticles in 80% water and fascinating nanorings in 90% water. The sensing of ampicillin sodium (AMP) antibiotic by the iridium(III) complex were also investigated by photoluminescent and electrochemiluminescent methods. The complex showed a good selectivity toward AMP antibiotic compared to sodium phenylacetate and other eight antibiotics. The detection limits for AMP antibiotic was 0.76 μg/mL. This work provided a new strategy for the design of iridium(III) complex-based aggregation-induced emission and electrochemiluminescence probes for the sensing application.

Aptamer Sensors for the Detection of Antibiotic Residues- A Mini-Review

Food security is a global issue, since it is closely related to human health. Antibiotics play a significant role in animal husbandry owing to their desirable broad-spectrum antibacterial activity. However, irrational use of antibiotics has caused serious environmental pollution and food safety problems; thus, the on-site detection of antibiotics is in high demand in environmental analysis and food safety assessment. Aptamer-based sensors are simple to use, accurate, inexpensive, selective, and are suitable for detecting antibiotics for environmental and food safety analysis. This review summarizes the recent advances in aptamer-based electrochemical, fluorescent, and colorimetric sensors for antibiotics detection. The review focuses on the detection principles of different aptamer sensors and recent achievements in developing electrochemical, fluorescent, and colorimetric aptamer sensors. The advantages and disadvantages of different sensors, current challenges, and future trends of aptamer-based sensors are also discussed.

Metal-organic framework-based nanomaterials as opto-electrochemical sensors for the detection of antibiotics and hormones: A review

Increasing trace levels of antibiotics and hormones in the environment and food samples are concerning and pose a threat. Opto-electrochemical sensors have received attention due to their low cost, portability, sensitivity, analytical performance, and ease of deployment in the field as compared to conventional expensive technologies that are time-consuming and require experienced professionals. Metal-organic frameworks (MOFs) with variable porosity, active functional sites, and fluorescence capacity are attractive materials for developing opto-electrochemical sensors. Herein, the insights into the capabilities of electrochemical and luminescent MOF sensors for detection and monitoring of antibiotics and hormones from various samples are critically reviewed. The detailed sensing mechanisms and detection limits of MOF sensors are addressed. The challenges, recent advances, and future directions for the development of stable, high-performance MOFs as commercially viable next-generation opto-electrochemical sensor materials for the detection and monitoring of diverse analytes are discussed.

Revolutionizing Food Safety with Quantum Dot-Polymer Nanocomposites: From Monitoring to Sensing Applications

The present review article investigates the prospective utilisation of quantum dot-polymer nanocomposites in the context of ensuring food safety. The text pertains to the advancement of nanocomposites, encompassing their distinctive optical and electrical characteristics, and their prospective to transform the detection and perception of food safety risks. The article explores diverse methodologies for producing nanocomposites and underscores their potential utility in identifying impurities, microorganisms, and harmful substances in food. The article provides an overview of the challenges and limitations associated with the utilisation of nanocomposites in food safety applications, encompassing concerns regarding toxicity and the necessity for standardised protocols. The review article presents a comprehensive examination of the present research status in this area and underscores the potential of quantum dots-polymer nanocomposites in transforming food safety monitoring and sensing.

Detection and removal technologies for ammonium and antibiotics in agricultural wastewater: Recent advances and prospective

With the extensive development of industrial livestock and poultry production, a considerable part of agricultural wastewater containing tremendous ammonium and antibiotics have been indiscriminately released into the aquatic systems, causing serious harms to ecosystem and human health. In this review, ammonium detection technologies, including spectroscopy and fluorescence methods, and sensors were systematically summarized. Antibiotics analysis methodologies were critically reviewed, including chromatographic methods coupled with mass spectrometry, electrochemical sensors, fluorescence sensors, and biosensors. Current progress in remediation methods for ammonium removal were discussed and analyzed, including chemical precipitation, breakpoint chlorination, air stripping, reverse osmosis, adsorption, advanced oxidation processes (AOPs), and biological methods. Antibiotics removal approaches were comprehensively reviewed, including physical, AOPs, and biological processes. Furthermore, the simultaneous removal strategies for ammonium and antibiotics were reviewed and discussed, including physical adsorption processes, AOPs, biological processes. Finally, research gaps and the future perspectives were discussed. Through conducting comprehensive review, future research priorities include: (1) to improve the stabilities and adaptabilities of detection and analysis techniques for ammonium and antibiotics, (2) to develop innovative, efficient, and low cost approaches for simultaneous removal of ammonium and antibiotics, and (3) to explore the underlying mechanisms that governs the simultaneous removal of ammonium and antibiotics. This review could facilitate the evolution of innovative and efficient technologies for ammonium and antibiotics treatment in agricultural wastewater.

Ultrasensitive amperometric determination of hand, foot and mouth disease based on gold nanoflower modified microelectrode

Given the widespread use of point-of-care testing for diagnosis of disease, micro-scale electrochemical deoxyribonucleic acid (DNA) biosensors have become a promising area of research owing to its fast mass transfer, high current density and rapid response. In this study, a gold nanoparticles modified gold microelectrode (AuNPs/Au-Me) was constructed to determine the hand, foot and mouth disease (HFMD)-related gene. The noble metal nanoparticles modification yielded ca. 7.4-fold increase in electroactive surface area of microelectrode, and the signal for HFMD-related gene was largely magnified. Under optimal conditions, the biosensor exhibited salient selectivity and sensitivity with a low detection limit of 0.3 fM (S/N = 3), which is sufficient for clinical diagnosis of HFMD. Additionally, the developed AuNPs/Au-Me was successfully applied to determining the polymerase chain reaction (PCR) amplified products of target gene. Thus, the electrochemical DNA biosensor possesses great potential in early-stage diagnosis and long-term monitoring of various disease.

Iron/iron oxide-based magneto-electrochemical sensors/biosensors for ensuring food safety: recent progress and challenges in environmental protection

Foodborne diseases have arisen due to the globalization of industry and the increase in urban population, which has led to increased demand for food and has ultimately endangered the quality of food. Foodborne diseases have caused some of the most common public health problems and led to significant social and economic issues worldwide. Food quality and safety are affected by microbial contaminants, growth-promoting feed additives (β-agonists and antibiotics), food allergens, and toxins in different stages from harvesting to storage and marketing of products. Electrochemical biosensors, due to their reduced size and portability, low cost, and low consumption of reagents and samples, can quickly provide valuable quantitative and qualitative information about food contamination. In this regard, using nanomaterials can increase the sensitivity of the assessment. Magnetic nanoparticle (MNP)-based biosensors, especially, are receiving significant attention due to their low-cost production, physicochemical stability, biocompatibility, and eco-friendly catalytic characteristics, along with magnetic, biological, chemical and electronic sensing features. Here, we provide a review on the application of iron-based magnetic nanoparticles in the electrochemical sensing of food contamination. The types of nanomaterials used in order to improve the methods and increase the sensitivity of the methods have been discussed. Then, we stated the advantages and limitations of each method and tried to state the research gaps for each platform/method. Finally, the role of microfluidic and smartphone-based methods in the rapid detection of food contamination is stated. Then, various techniques like label-free and labelled regimes for the sensitive monitoring of food contamination were surveyed. Next, the critical role of antibody, aptamer, peptide, enzyme, DNA, cells and so on for the construction of specific bioreceptors for individual and simultaneous recognition by electrochemical methods for food contamination were discussed. Finally, integration of novel technologies such as microfluidic and smartphones for the identification of food contaminations were investigated. It is important to point out that, in the last part of each sub-section, attained results of different reports for each strategy were compared and advantages/limitations were mentioned.

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.

Advances in the screening of antimicrobial compounds using electrochemical biosensors: is there room for nanomaterials?

The abusive use of antimicrobial compounds and the associated appearance of antimicrobial resistant strains are a major threat to human health. An improved antimicrobial administration involves a faster diagnosis and detection of resistances. Antimicrobial susceptibility testing (AST) are the reference techniques for this purpose, relying mainly in the use of culture techniques. The long time required for analysis and the lack of reproducibility of these techniques have fostered the development of high-throughput AST methods, including electrochemical biosensors. In this review, recent electrochemical methods used in AST have been revised, with particular attention on those used for the evaluation of new drug candidates. The role of nanomaterials in these biosensing platforms has also been questioned, inferring that it is of minor importance compared to other applications.

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.

Emerging application of nanotechnology for mankind

Nanotechnology has proven to be the greatest multidisciplinary field in the current years with potential applications in agriculture, pollution remediation, environmental sustainability, as well as most recently in pharmaceutical industries. As a result of its physical, chemical, and biological productivity, resistance, and matricular organization at a larger scale, the potential of nanocomposites revealed different sorts of assembling structures via testing. Biosensors are known some specifically promising inventions whereas carbon nanotube, magnetic nanoparticles (NPs), quantum dots, and gold NPs showed capability to repair damaged cells, molecular docking, drug-delivery, and nano-remediation of toxic elements. PEGylated(Poly ethyl glycol amyl gated) redox-responsive nanoscale COFs drug delivery from AgNPs and AuNPs are known to be sun blockers in sunscreen lotions. The emerging trends and yet more to be discovered to bridge the gaps forming in the field of nanotechnology, especially insights into environmental concerns and health issues most importantly the food web which is connected with the well beings of mankind to perform its tasks giving necessary results. The current review detailed emerging role of nanomaterials in human life.

Supplementary Information

The online version contains supplementary material available at 10.1007/s42247-023-00461-8.

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.

Environmental drivers and interaction mechanisms of heavy metal and antibiotic resistome exposed to amoxicillin during aerobic composting

The environmental accumulation and spread of antibiotic resistance pose a major threat to global health. Aerobic composting has become an important hotspot of combined pollution [e.g., antibiotic resistance genes (ARGs) and heavy metals (HMs)] in the process of centralized treatment and resource utilization of manure. However, the interaction mechanisms and environmental drivers of HMs resistome (MRGs), antibiotic resistance (genotype and phenotype), and microbiome during aerobic composting under the widely used amoxicillin (AMX) selection pressure are still poorly understood. Here, we investigated the dynamics of HMs bioavailability and their MRGs, AMX-resistant bacteria (ARB) and antibiotic resistome (ARGs and intI1), and bacterial community to decipher the impact mechanism of AMX by conducting aerobic composting experiments. We detected higher exchangeable HMs and MRGs in the AMX group than the control group, especially for the czrC gene, indicating that AMX exposure may inhibit HMs passivation and promote some MRGs. The presence of AMX significantly altered bacterial community composition and AMX-resistant and -sensitive bacterial structures, elevating antibiotic resistome and its potential transmission risks, in which the proportions of ARB and intI1 were greatly increased to 148- and 11.6-fold compared to the control group. Proteobacteria and Actinobacteria were significant biomarkers of AMX exposure and may be critical in promoting bacterial resistance development. S0134_terrestrial_group was significantly negatively correlated with bla_TEM and czrC genes, which might play a role in the elimination of some ARGs and MRGs. Except for the basic physicochemical (MC, C/N, and pH) and nutritional indicators (NO₃ ^--N, NH₄ ⁺-N), Bio-Cu may be an important environmental driver regulating bacterial resistance during composting. These findings suggested the importance of the interaction mechanism of combined pollution and its synergistic treatment during aerobic composting need to be emphasized.

Electrochemical immunosensor based on gold-thionine for detection of subarachnoid hemorrhage biomarker

Introduction: In clinical work, the realization of an early diagnosis of Subarachnoid hemorrhage (SAH) is primarily based on conventional computed tomography (CT), MR angiography, transcranial Doppler (TCD) ultrasound, and neurological assessments. However, the association between imaging manifestations and clinical findings is insufficiently perfect, particularly in SAH patients in acute phases with a lower amount of blood. The establishment of a direct, rapid and ultra-sensitive detection method based on electrochemical biosensors has emerged as a new competitive challenge in disease biomarkers research. Methods: In this study, a novel free-labeled electrochemical immunosensor for rapidly and sensitively detecting IL-6 in subarachnoid hemorrhage (SAH) blood has been developed using Au nanospheres-thionine composites (AuNPs/THI) as the interface modified on the electrode. Then, we detected IL-6 in blood samples from SAH patients by (enzyme-linked immunosorbent assay) ELISA and electrochemical immunosensor. Results: Under the best conditions, the developed electrochemical immunosensor exhibited a wide linear range from 10^-2 ng/mL to 10² ng/mL with a low detection limit of 1.85 pg/mL. Furthermore, when the immunosensor was employed in the analysis of IL-6 in 100% serum, the results obtained by electrochemical immunoassay were consistent with those obtained by ELISA without suffering from other significant biological interference. Discussion: The designed electrochemical immunosensor realizes the detection of IL-6 in actual serum samples with high accuracy and sensitivity, and could potentially become a promising technique for applications in the clinical diagnosis of SAH.

Development and Validation for Quantification of Cephapirin and Ceftiofur by Ultraperformance Liquid Chromatography with Triple Quadrupole Mass Spectrometry

Cross contamination of β-lactams is one of the highest risks for patients using pharmaceutical products. Penicillin and some non-penicillin β-lactams may cause potentially life-threatening allergic reactions. The trace detection of β-lactam antibiotics in cleaning rinse solutions of common reactors and manufacturing aids in pharmaceutical facilities is very crucial. Therefore, the common facilities adopt sophisticated cleaning procedures and develop analytical methods to assess traces of these compounds in rinsed solutions. For this, a highly sensitive and reproducible ultra-performance liquid chromatography with triple quadrupole mass spectrometry (UHPLC-MS/MS) method was developed for the analysis of Cephapirin and Ceftiofur. As per the FDA guidelines described in FDA-2011-D-0104, the contamination of these β-lactam antibiotics must be regulated. The analysis was performed on an XBridge C18 column with 100 mm length, 4.6 mm diameter, and 3.5 µm particle size at an oven temperature of about 40 °C. The mobile phase was composed of 0.15% formic acid in water and acetonitrile as mobile phases A and B, and a flow rate was set to 0.6 mL/min. The method was validated for Cephapirin and Ceftiofur. The quantification precision and accuracy were determined to be the lowest limit of detection 0.15 parts per billion (ppb) and the lowest limit of quantification 0.4 ppb. This method was linear in the range of 0.4 to 1.5 ppb with the determination of coefficient (R2 > 0.99). This sensitive and fast method was fit-for-purpose for detecting and quantifying trace amounts of β-lactam contamination, monitoring cross contamination in facility surface cleaning, and determining the acceptable level of limits for regulatory purposes.

Aptasensing of ciprofloxacin residue using graphene oxide modified with gold nanoparticles and branched polyethyleneimine

Precise monitoring of antibiotic residues in aqueous solution is of vital significance for safeguarding the environment and food resources. Herein, a convenient platform was fabricated for the electrochemical assay of ciprofloxacin (CFX) in real milk samples using aminated aptamer and graphene oxide nanogold-functionalized branched polyethyleneimine (GO-PEI-AuNPs) nanocomposite. For the first time, a gold electrode was modified with GO-PEI-AuNPs. The modified surface endowed excellent electrochemical substrates with large surface areas, excellent electron transfer rates, and suitable capabilities to firmly attach high amounts of aptamer. After further modification of substrate with CFX specific aptamer a recognition probe enabling selective and sensitive determination of CFX was realized. All of the aptasensor fabrication steps were surveyed via cyclic voltammetry techniques. The construction and morphology of the GO-PEI-AuNPs composite were evaluated by UV-Vis spectroscopy, transmission electron microscopy, and field emission scanning electron microscopy. Under optimal conditions, the suggested scaffold can offer an acceptable linear range of 0.001 to 100 μM and a low limit of quantification of 0.001 μM for selective and sensitive monitoring of CFX in real samples. The effectiveness of the apta-assay was confirmed by detection of CFX in pasteurized and local milk samples for which suitable analytical results were achieved. It is expected that the developed substrate can be facilely extended to other aptamer-based multiplex screening platforms in actual food and environmental samples.

A convenient platform was fabricated for the electrochemical assay of ciprofloxacin using aminated aptamer immobilized in GO-PEI-AuNPs nanocomposite.

Nanomaterials-based portable electrochemical sensing and biosensing systems for clinical and biomedical applications

Miniaturized electrochemical sensing systems are employed in day-to-day uses in the several area from public health to scientific applications. A variety of electrochemical sensor and biosensor systems may not be effectively employed in real-world diagnostic laboratories and biomedical industries due to their limitation of portability, cost, analytical period, and need of skilled trainer for operating devices. The design of smart and portable sensors with high sensitivity, good selectivity, rapid measurement, and reusable platforms is the driving strength for sensing glucose, lactate, hydrogen peroxide, nitric oxide, mRNA, etc. The enhancement of sensing abilities of such sensor devices through the incorporation of both novel sensitive nanomaterials and design of sensor strategies are evidenced. Miniaturization, cost and energy efficient, online and quantitative detection and multiple sensing ability are the beneficial of the nanostructured-material-based electrochemical sensor and biosensor systems. Owing to the discriminating catalytic action, solidity and biocompatibility for designing sensing system, nanoscale materials empowered electrochemical detection systems are accomplished of being entrenched into/combined with portable or miniaturized devices for specific applications. In this review, the advance development of portable and smart sensing/biosensing systems derived from nanoscale materials for clinical and biomedical applications is described.

Graphical Abstract

Construction of a dual-model aptasensor based on G-quadruplexes generated via rolling circle amplification for visual/sensitive detection of kanamycin

A dual-model colorimetric and electrochemical aptasensor was designed using a large number of G-quadruplexes generated by rolling circle amplification (RCA). Specific binding between target and aptamer during RCA yielded large numbers of G-quadruplexes. A colorimetric sensor was fabricated based on the interaction between the G-quadruplex and hemin, which altered the 3,3',5,5'-Tetramethylbenzidine (TMB)-catalyzed color reaction and facilitated the visual and semi-quantitative detection of kanamycin. An electrochemical sensor was constructed based on the strong interaction between the G-quadruplex and the methylene blue electrical signal molecule. Combining nanocomposites multi-walled carbon nanotubes-chitosan/gold nanoparticles (MWCNTs-CS/AuNPs) and RCA realized double-amplified electrochemical signals. Under optimized conditions, a linear relationship was obtained as the logarithm of different concentrations of kanamycin (KAN). The colorimetric aptasensor had a linear range of 1 × 10² nM to 1 × 10³ nM with a detection limit of 1.949 nM. The electrochemical aptasensor had wider a linear range from 1 × 10^-3 nM to 2.5 × 10³ nM and a lower detection limit of 0.333 pM. The sensor combined the advantages of simple colorimetric visualization with the ultra-precision of electrochemical methods. Aptasensor showed good specificity and prevented interference. Furthermore, the prepared dual-model aptasensor facilitated the practical monitoring of KAN in milk.