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Currently, electrochemical sensors are being developed and widely used in various fields, and new materials are being explored to enhance the precision and selectivity of the sensors. The present investigation involved the fabrication of a Fe/graphene/porphyrin nanocomposite through self-assembly, wherein the individual porphyrin molecules were arranged on the Fe/graphene nanomaterials' surface. The Fe/graphene nanoparticles were synthesized utilizing a green approach, wherein leaf extract was employed as the reducing agent. The resulting materials underwent comprehensive characterization using a range of contemporary techniques, including scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and Raman spectroscopy. The study's findings revealed that the nanocomposites of Fe/graphene/porphyrin comprised zero-valent iron nanoparticles, exhibiting an average particle size ranging from 15 to 60 nm. These nanoparticles were seen to be evenly dispersed across the graphene sheets. The presence of nanostructure porphyrin nanofibers, measuring 20 nm in diameter, was also shown to exhibit strong integration with the surface of the Fe/graphene nanomaterials. The electrochemical properties of the Fe/graphene/porphyrin nanocomposite were also investigated, demonstrating that the prepared material could be effectively employed as a sensing electrode in the electrochemical sensor for detecting Chloramphenicol (CAP) through CV, EIS, and DPV techniques using a three-electrode electrochemical system. Under optimal conditions, Fe/graphene/porphyrin exhibited a high current response when detecting CAPs. Electrochemical sensors created using Fe/graphene/porphyrin nanocomposite have high stability and repeatability, and they hold promise in developing sensors capable of identifying other antibiotic residues in agriculture.

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Antibiotics are widely used for treating bacterial infections. However, excessive or improper use of antibiotics can pose a serious threat to human health and water environments, and thus, developing cost-effective, portable and effective strategies to analyze and detect antibiotics is highly desired. Herein, we reported a responsive photonic hydrogel (RPH)-based optical biosensor (PPNAH) with superior recyclability for sensitive and colorimetric determination of a typical ß-lactam antibiotic penicillin G (PG) in water. This sensor was composed of poly(N-isopropylacrylamide-co-acrylamide) smart hydrogel with incorporated penicillinase and Fe3O4@SiO2 colloidal photonic crystals (CPCs). The sensor could translate PG concentration signals into changes in the diffraction wavelength and structural color of the hydrogel. It possessed high sensitivity and selectivity to PG and excellent detection performances for other two typical ß-lactam antibiotics. Most importantly, due to the unique thermosensitivity of the poly(N-isopropylacrylamide) moieties in the hydrogel, the PG-responded PPNAH sensor could be facilely regenerated via a simple physical method at least fifty times while without compromising its response performance. Besides, our sensor was suitable for monitoring the PG-contaminated environmental water and displayed satisfactory detection performances. Such a sensor possessed obvious advantages of superior recyclability, highly chemical stability, low production cost, easy fabrication, wide range of visual detection, simple and intuitive operation for PG detection, and environmental-friendliness, which holds great potential in sensitive and colorimetric detection of the PG residues in polluted water.

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Antibiotics play an essential role in the treatment of various diseases. However, the overuse of antibiotics has led to the pollution of water bodies and food safety, affecting human health. Herein, we report a dual-emission MOF-based flexible sensor for the detection of antibiotics in water, which was prepared by first encapsulating rhodamine B (RhB) by a zeolite imidazolium ester skeleton (ZIF-8) and then blending it with polyvinylidene difluoride (PVDF). The luminescent properties, structural tunability, and flexible porosity of the MOF-based composites were combined with the processability and flexibility of polymers to prepare luminescent membranes. The sensor is capable of dual-emission ratiometric fluorescence sensing of nitrofurantoin (NFT) and oxytetracycline (OTC), exhibiting sensitive detection of fluorescence burst and fluorescence enhancement, respectively, with detection limits of 0.012 µM and 8.9 nM. With the advantages of visual detection, high sensitivity, short detection time, and simplicity, the highly sensitive ratiometric fluorescent flexible sensor has great potential for detecting antibiotics in an aqueous environment. It will further stimulate interest in luminescent MOF-based mixed matrix membranes and their sensing applications.

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Developing efficient and sensitive MOF-based luminescence sensors for bioactive molecule detection is of great significance and remains a challenge. Benefiting from favorable chemical and thermal stability, as well as excellent luminescence performance, a porous Zn(II)Ho(III) heterometallic-organic framework (ZnHoMOF) was selected here as a bifunctional luminescence sensor for the early diagnosis of a toluene exposure biomarker of hippuric acid (HA) through "turn-on" luminescence enhancing response and the daily monitoring of NFT/NFZ antibiotics through "turn-off" quenching effects in aqueous media with high sensitivity, acceptable selectivity, good anti-interference, exceptional recyclability performance, and low detection limits (LODs) of 0.7 ppm for HA, 0.04 ppm for NFT, and 0.05 ppm for NFZ. Moreover, the developed sensor was employed to quantify HA in diluted urine samples and NFT/NFZ in natural river water with satisfactory results. In addition, the sensing mechanisms of ZnHoMOF as a dual-response chemosensor in efficient detection of HA and NFT/NFZ antibiotics were conducted from the view of photo-induced electron transfer (PET), as well as inner filter effects (IFEs), with the help of time-dependent density functional theory (TD-DFT) and spectral overlap experiments.

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Antibiotic pollution is an ever-growing concern that affects the growth of plants and the well-being of animals and humans. Research on antibiotics remediation from aqueous media has grown over the years and previous reviews have highlighted recent advances in antibiotics remediation technologies, perspectives on antibiotics ecotoxicity, and the development of antibiotic-resistant genes. Nevertheless, the relationship between antibiotics solution chemistry, remediation technology, and the interactions between antibiotics and adsorbents at the molecular level is still elusive. Thus, this review summarizes recent literature on antibiotics remediation from aqueous media and the adsorption perspective. The review discusses the principles, mechanisms, and solution chemistry of antibiotics and how they affect remediation and the type of adsorbents used for antibiotic adsorption processes. The literature analysis revealed that: (i) Although antibiotics extraction and detection techniques have evolved from single-substrate-oriented to multi-substrates-oriented detection technologies, antibiotics pollution remains a great danger to the environment due to its trace level; (ii) Some of the most effective antibiotic remediation technologies are still at the laboratory scale. Thus, upscaling these technologies to field level will require funding, which brings in more constraints and doubts patterning to whether the technology will achieve the same performance as in the laboratory; and (iii) Adsorption technologies remain the most affordable for antibiotic remediation. However, the recent trends show more focus on developing high-end adsorbents which are expensive and sometimes less efficient compared to existing adsorbents. Thus, more research needs to focus on developing cheaper and less complex adsorbents from readily available raw materials. This review will be beneficial to stakeholders, researchers, and public health professionals for the efficient management of antibiotics for a refined decision.

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Efficient and rapid detection methods for antibiotics are of great practical importance to achieve environmental safety and protect human health. PEC sensors have been widely employed in antibiotics analysis due to their advantages of low background signal, high sensitivity, simple operation, and wide dynamic response range. This review is focused on the recent progress in photoactivities regulating of inorganic semiconductors from metal oxides/sulfides, metal-based quantum dots to metal-free carbon nitride and various types of PEC sensors in antibiotics monitoring which covers sensing strategies without or with a recognition element (antibody, molecularly imprinted polymer and aptamer). Finally, the challenges and the development prospects of the PEC sensors for antibiotics detection are discussed.

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The surface-enhanced Raman scattering (SERS) technique with ultrahigh sensitivity has gained attention to meet the increasing demands for food safety analysis. The integration of machine learning and SERS facilitates the practical applicability of sensing devices. In this study, a machine learning-driven 3D plasmonic cavity-in-cavity (CIC) SERS platform is proposed for sensitive and quantitative detection of antibiotics. The platform is prepared by transferring truncated concave nanocubes (NCs) to an obconical-shaped template surface. Owing to the triple synergistic enhancement effect, the highly ordered 3D CIC arrays improve the simulated electromagnetic field intensity and experimental SERS activity, demonstrating a 33.1-fold enhancement compared to a typical system consisting of Au NCs deposited on a flat substrate. The integration of machine learning and Raman spectroscopy eliminates subjective judgments on the concentration of detectors using a single feature peak and achieves accurate identification. The machine learning-driven CIC SERS platform is capable of detecting ampicillin traces in milk with a detection limit of 0.1 ppm, facilitating quantitative analysis of different concentrations of ampicillin. Therefore, the proposed platform has potential applications in food safety monitoring, health care, and environmental sampling.

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Due to their advantages of good flexibility, low cost, simple operations, and small equipment size, electrochemical sensors have been commonly employed in food safety. However, when they are applied to detect various food or drug samples, their stability and specificity can be greatly influenced by the complex matrix. By combining electrochemical sensors with molecular imprinting techniques (MIT), they will be endowed with new functions of specific recognition and separation, which make them powerful tools in analytical fields. MIT-based electrochemical sensors (MIECs) require preparing or modifying molecularly imprinted polymers (MIPs) on the electrode surface. In this review, we explored different MIECs regarding the design, working principle and functions. Additionally, the applications of MIECs in food and drug safety were discussed, as well as the challenges and prospects for developing new electrochemical methods. The strengths and weaknesses of MIECs including low stability and electrode fouling are discussed to indicate the research direction for future electrochemical sensors.

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In order to achieve on-site fluorescent detection of antibiotic doxycycline (DOC) residue, a new kind of fluorescent organosilicon nanodots (OSiNDs) was successfully constructed by a one-pot strategy and used as a novel ratiometric fluorescent probe. This method could enhance the fluorescence of DOC by conformational fixation on the surface of OSiNDs, and subsequently induced fluorescence resonance energy transfer (FRET). Control experimental results showed that phenylamine functional groups on the as-prepared OSiNDs possessed favorable interactions with DOC by hydrogen bond/π-π stacking, leading to both conformational change of DOC molecules and fluorescence resonance energy transfer process from OSiNDs to DOC. This method was then adapted and optimized for visual sensitive and selective detection of DOC based on ratiometric fluorescence signal, displaying a good linear range for DOC in the range of 1-35 µM with an excellent limit detection of ∼80 nM. Other tetracycline derivatives (TCs) and possible interferences have little influence on the determination of DOC using the method. The spike and recovery test of DOC in real water samples demonstrated the feasibility of the OSiNDs for DOC assay in practical samples and a test paper was fabricated with OSiNDs loading, achieving easy and visual detection of DOC by naked eyes.

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Given increasing concern regarding antibiotic environmental contamination, there is immediate need to monitor antibiotic levels to effectively control pollution. In this study, we used a photoelectrochemical aptasensor based on TiO2@MoS2 spiral nanoarrays to detect chloramphenicol (CAP) in antibiotics. Nanoarrays were directly grown on fluorine-doped tin oxide (FTO) conductive glass with excellent biochemical stability, while aptamer-SH were immobilized by chemical binding on a synthetic TiO2@MoS2 nanoarray. Results show that the photocurrents were reduced in the presence of photoelectrochemistry associated with specific selection of aptamer for CAP. When the measurement of the fabricated nanomaterial chip was carried out using a three-electrode system, we found a highly specific and stable detection of chloramphenicol that ranged between 0.1 pM and 1 µM, with the detection limit of 0.1 pM. In addition, we obtained satisfactory results when real sample were used to validate the potential of photoelectrochemical (PEC) aptasensor for detecting chloramphenicol content in milk. Our results demonstrate that photoelectrochemical aptasensor is conducive to the development of less toxic multifunctional nanomaterials, making the biosensor more robust and environmentally friendly. Therefore, photoelectrochemical aptasensor can be widely applied in the field of environmental monitoring.

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To achieve the ultrastable LMOFs with predominant luminescent sensing performances, the aromatic π-electron mixed ligands strategy was introduced, and the ternary LMOF of {[Zn2(HDDB)(bib)1.5]·3H2O}n (1), was fabricated based on 3,5-di(2',4'-dicarboxylphenyl)benozoic acid (H5DDB) and the N-donor of meta-bis(imidazol-1-yl)benzene (bib) under mixed solvothermal condition. LMOF 1 features the first reported 3D 3,4,4-c {62.83.10}{62.8}2{63.82.10}2 framework with 21.2 % porosity as well as high thermal and chemical stability. Further luminescent sensing showed that LMOF 1 as a bifunctional chemosensor possessing predominant detectability for sensitive detect the hexavalent chromates and nitroimidazoles/nitrofurans antibiotics in water through strong luminescent quenching effects, with excellent reusability as well as trace detection limits. Moreover, luminescent quenching mechanisms were further investigated from electron transfer and energy transfer viewpoints.

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The widespread use of antibiotics caused severe problems of antibiotic residues in foodstuffs and water, posing a serious threat to public health and thus urging the development of sensitive, selective, and rapid detection methods for antibiotics. In this study, a fluorescence resonance energy transfer (FRET)-based system is developed for the multiplexed analysis of chloramphenicol (CAP) and streptomycin (Strep) with detection limits of 2.51 and 8.69µg l-1, respectively. The FRET-based system consists of Cy3-tagged anti-CAP aptamer-conjugated gold nanoparticles (AuNPs) (referred to as AuNPs-AptCAP) and Cy5-tagged anti-Strep aptamer-conjugated AuNPs (referred to as AuNPs-AptStrep). In addition, AuNPs-AptCAP and AuNPs-AptStrep have been demonstrated to serve as signal transducers for implementing a series of logic operations such as YES, NOT, INH, OR, (2-4)-Decoder and even more complicated multi-level logic gates (OR-INH). Based on the outputs of logic operations, it could be figured out whether targeted analytes were present or not, thus enabling multiplex sensing and evaluation of pollution status. This proof of concept study might provide a new route for the enhanced sensing performance to distinguish different pollution status as well as the design of molecular mimics of logic elements to demonstrate better applicability.

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Misuse of antibiotics has recently been considered a global issue because of its harmful effects on human health. Since conventional methods have numerous limitations, it is necessary to develop fast, simple, sensitive, and reproducible methods for the detection of antibiotics. Among numerous recently developed methods, aptasensors are fascinating because of their good specificity, sensitivity and selectivity. These kinds of biosensors combining aptamer with colorimetric applications of gold nanoparticles to recognize small molecules are becoming more popular owing to their advantageous features, for example, low cost, ease of use, on-site analysis ability using naked eye and no prerequisite for modern equipment. In this review, we have highlighted the recent advances and working principle of gold nanoparticles based colorimetric aptasensors as promising methods for antibiotics detection in different food and environmental samples (2011-2020). Furthermore, possible advantages and disadvantages have also been summarized for these methods. Finally, the recent challenges, outlook, and promising future perspectives for developing novel aptasensors are also considered.

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ABSTRACT: This study dealt with the fabrication of an impedimetric biosensor based on nanomaterial modified with pencil graphite electrode for the detection of tetracycline (TET) in milk samples. For response of the impedimetric aptasensor to be improved, the influence of different parameters (immobilization time of reduced grapheme oxide, time of aptamer, and TET binding, and concentration of aptamer) was optimized. In optimum conditions, the aptasensor provided a concentration range within 1 × 10-16 - 1 × 10-6 M and with a limit of detection of 3 × 10-17 M TET. The proposed impedimetric aptasensor was then used in milk samples analysis, and the acceptable recovery was achieved ranging from 92.8 to 102.1%. According to this study, the combination of an aptamer and electrochemical impedance spectroscopy is a promising method for detection of TET in milk samples with high reproducibility and stability.

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Antibiotics, a kind of secondary metabolite with antipathogen effects as well as other properties, are produced by microorganisms (including bacterium, fungi, and actinomyces) or higher animals and plants during their lives. Furthermore, as a chemical, an antibiotic can disturb the developmental functions of other living cells. Moreover, it is impossible to avoid its pervasion into all kinds of environmental media via all kinds of methods, and it thus correspondingly becomes a trigger for environmental risks. As described above, antibiotics are presently deemed as a new type of pollution, with their content in media (for example, water, or food) as the focus. Due to their special qualities, nanomaterials, the most promising sensing material, can be adopted to produce sensors with extraordinary detection performance and good stability that can be applied to detection in complicated materials. For low-dimensional (LD) nanomaterials, the quantum size effect, and dielectric confinement effect are particularly strong. Therefore, they are most commonly applied in the detection of antibiotics. This article focuses on the influence of LD nanomaterials on antibiotics detection, summarizes the application of LD nanomaterials in antibiotics detection and the theorem of sensors in all kinds of antibiotics detection, illustrates the approaches to optimizing the sensitivity of sensors, such as mixture and modification, and also discusses the trend of the application of LD nanomaterials in antibiotics detection.

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Cerium doped magnetite nanoparticle (CDM) was synthesized via a co-precipitation method and used as the co-reactant of luminol-K3Fe(CN)6 chemiluminescent system. The physical-chemical features of CDM were studied by XPS, XRD, HRTEM, FESEM, VSM, BET, and FTIR analyses. This simple and highly sensitive nanoprobe enabled the determination of minor concentrations of metronidazole (MNZ). Owing to the quenching efficacy of MNZ in the studied chemiluminescence system, a linear range of 3.47 × 10-6-9.37 × 10-5 mol/L was obtained with a limit of detection of 3.91 × 10-7 mol/L. This biosensor was used for MNZ detection in human serum samples, which was highly efficient. The outcomes of this study give credit to the proposed biosensor to be applied for detection of MNZ in biological samples.

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The increasing global reports on the occurrence of macrolide antibiotics resistance, especially erythromycin (Ery) resistant strains, suggests the possible presence of these antibiotics in the environment hence, their inclusion in the EU watchlist of water pollutants. Consequently, there is an urgent need for the development of portable and cost effective analytical sensing devices for their monitoring in water. The combination of molecularly imprinted polymer (MIP) as a sensing element with a portable electrochemical transducer such as screen printed electrode (SPE) may offer a valuable approach for the desired routine environmental monitoring. This work demonstrates the preparation of an electrochemical MIP-based sensor for Ery detection in aqueous media. Ery-selective MIP, Ery-MIP was generated directly on SPE, Ery-MIP/SPE via electrochemical polymerization of m-phenylenediamine (mPD). The optimization of sensor performance was achieved with special attention given to the selection of functional monomer, template removal, polymer thickness and incubation time. Ery-MIP/SPE sensor demonstrated the ability to discriminate target analyte against very close analogues i.e clarithromycin and azithromycin in both PBS and tap water. In addition, Ery-MIP/SPE could detect Ery down to low limits (LOD = 0.1 nM and LOQ = 0.4 nM) and exhibited good recovery in tap water. The presented analytical approach could be potentially suited and/or further developed for adequate monitoring of Ery as well as other macrolides in environmental water.

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Simultaneous and sensitive detection of various antibiotic residues in one sample is essential to evaluation of food safety status. Herein, a multiplexed electrochemical aptasensor for multiplex antibiotics detection, with kanamycin (KANA) and ampicillin (AMP) as representative analytes, was designed by using metal ions encoded apoferrtin probes and double stirring bars-assisted target recycling for signal amplification. The encoded probes were prepared by apoferritin loading Cd2+ and Pb2+ ions and labeling with duplex DNAs (aptamers corresponding to KANA and AMP hybrid with its complementary DNA sequence), respectively. In the presence of KANA and AMP, the targets can recurrently react with the probes on the bars, and then replace a lot of Apo-Mencoded signal tags into supernatant. The peak currents of Cd2+and Pb2+from the tags corresponding with the concentrations of KANA and AMP were detected by square wave voltammetry in one run. As a result, KANA and AMP can be detected simultaneously within the range from 0.05 pM to 50 nM. And the detection limits were 18 fM KANA and 15 fM AMP (S/N = 3). The assay was testified to detect KANA and AMP residues with consistent results of ELISA in samples, e.g. milks and fishes. The assay was highly-sensitive, selective, cost-effective and easy-to-operate due to Apo-M encoded probes with high loading capacity of signal source substances. Moreover, double stirring bar-assisted target recycling, which was enzyme-free and could overcome matrix interference, was fabricated for signal amplification. Thus, the assay showed potential advantages for sensitively screening of antibiotic residues in foods.

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The development of a feasible antibiotic detection method is important in water quality analysis. In this study, we developed a metal-organic framework (MOF)-aptamer-3,3',5,5'-tetramethylbenzidine (TMB)-H2O2-based sensing platform composed of the reaction variable of TMB catalytic oxidation as the label (from colorless to blue) and aptamer as the target recognition element for antibiotic detection. The platform works by calculating the relation between the antibiotic concentration and the resultant decrease in MOF's catalytic activity. Basing from the comparison of typical iron-based MOF materials (Fe-MIL-53, Fe-MIL-88A, and Fe-MIL-100), we selected Fe-MIL-53 to obtain an improved signal amplification effect. The outstanding performance of the Fe-MIL-53-based sensing platform can be attributed to its topological flexibility and small electron transfer impedance. In addition, a signal increment of up to 86% was obtained with an intensified gold nanoparticle (AuNP)-supported aptamer. The inhibitory catalytic activity stemmed from the coating of antibiotic-(AuNP-aptamer) conjugates onto the outer surface of the MOF material, which increased the impedance and decreased the electron transfer efficiency. Validation results indicated that the platform showed high selectivity and sensitivity (i.e., wide linearity range of 50-200 nM, detection limit up to 8.1 ng/mL, and recovery rate of 106%-110%) for chloramphenicol detection and universal applicability for other antibiotics, including ampicillin, tetracycline, and oxytetracycline. In general, the detection reliability and easy operation of this platform render it a promising candidate for antibiotic detection in future water quality monitoring practices.

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Microchip electrophoresis (MCE) was a good available method for high-throughput and rapid detecting chemical pollutants in food samples. However, many of the reported MCE assays involve complex design of microchip, laborious operation and poor universality which limited its promotion in multiple antibiotics' detection. Herein, a multiplexed aptasensor was developed based on a universal double-T type microchip to one-step and simultaneously detect several antibiotics within 3 min using chloramphenicol (CAP) and kanamycin (Kana) as representatives. Besides, a novel stir-bar assisted DNA multi-arm junctions recycling (MAJR) strategy was designed for transducing and amplifying the signal. The brief detection mechanism was as following: the added CAP and Kana can specifically react with their aptamer probes on the stir-bar and produce different single-stranded DNA primer, respectively. Afterwards, the primers can trigger MAJR to form a lot of three- and four-arm DNA junctions corresponding to different targets. The DNA multi-arm junctions can be easily separated and detected by MCE for quantification. Moreover, the stir-bar can facilitate phase separation and obviously eliminate matrix interference in food. The assay was successfully applied in milk and fish samples, showing excellent selectivity and sensitivity with a detection limits of 0.52 pg mL-1 CAP and 0.41 pg mL-1 Kana (S/N = 3). Thus, the assay holds a great potential application for screening of antibiotics in food.

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