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The ecotoxicological impact of leptospermone, a β-triketone bioherbicide, on the bacterial community of two arable soils was investigated. Soil microcosms were exposed or not (control, 0×) to leptospermone applied at 1× or 10× recommended dose. Leptospermone was moderately adsorbed to both soils (i.e.: Kfa  1.2 and Koc  140 ml.g-1). Dissipation of leptospermone was lower in sterilized than in unsterilized soils suggesting that it was mainly influenced by biotic factors. Within 45 days, leptospermone disappeared almost entirely from one of the two soils (i.e. DT50 < 10 days), while 25% of the leptospermone remained in the other. The composition of the microbial community assessed by qPCR targeting 11 microbial groups was found to be significantly modified in soil microcosms exposed to leptospermone. Pyrosequencing of 16S rRNA gene amplicons showed a shift in the bacterial community structure and a significant impact of leptospermone on the diversity of the soil bacterial community. Changes in the composition as well as in the α- and β-diversity of microbial community were transient in the soil able to fully dissipate the leptospermone. They were persistent in the soil where leptospermone remained. To conclude the bacterial community of the two soils was sensitive to leptospermone and its resilience was observed only when leptospermone was fully dissipated.

Background Tropical coral reefs cover only ca. 0.1% of the Earth’s surface but harbour exceptional marine biodiversity and provide vital ecosystem services to millions of people living nearby. They are currently threatened by global (e.g. climate change) and local (e.g. chemical pollution) stressors that interact in multiple ways. While global stressors cannot be mitigated by local actions alone, local stressors can be reduced through ecosystem management. Here, we aimed to systematically review experimental studies assessing the toxicity of chemical pollutants to tropical reef-building corals to generate accessible and usable knowledge and data that can be used to calculate measurement endpoints in ecological risk assessment. From the quantitative estimates of effects, we determined toxicity thresholds as the highest exposures tested at which no statistically significant adverse effects were observed, and we compared them to regulatory predicted no effect concentrations for the protection of marine organisms, to assess whether these reference values are indeed protective of corals. Methods The evidence was taken from a systematic map of the impacts of chemicals arising from human activity on tropical reef-building corals published in 2021. All studies in the map database corresponding to the knowledge cluster “Evidence on the ecotoxicological effects of chemicals on corals” were selected. To identify subsequently published literature, the search was updated using a subset of the search string used for the systematic map. Titles, abstracts and full-texts were screened according to the criteria defining the selected cluster of the map. Because the eligibility criteria for the systematic review are narrower than the criteria used to define the cluster in the systematic map, additional screening was performed. Studies included were critically appraised and each study was rated as low, unclear, medium, or high risk of bias. Data were extracted from the studies and synthesised according to a strategy dependent on the type of exposure and outcome. Review findings The systematic review reports the known effects of chemical exposures on corals from 847 studies corresponding to 181 articles. A total of 697 studies (161 articles) were included in the quantitative synthesis and 150 studies (50 articles) in the narrative synthesis of the findings. The quantitative synthesis records the effects of 2706 exposure concentrations-durations of 164 chemicals or mixtures of chemicals, and identifies 105 toxicity thresholds corresponding to 56 chemicals or mixtures of chemicals. When toxicity thresholds were compared to reference values set for the protection of marine organisms by environmental agencies, the reference values appear to be protective of corals for all but three chemicals assessed: the metal copper and the pesticides diuron and irgarol 1051. Conclusions This open-access database of known ecotoxicological effects of chemical exposures on corals can assist managers in the ecological risk assessment of chemicals, by allowing easy determination of various ecotoxicological thresholds. Several limitations of the toxicity tests synthesised here were noted (in particular the lack of measurement of effective concentrations for more than half of the studies). Overall, most of the currently available data on coral toxicity should be replicated independently and extended to corals from less studied geographical regions and functional groups.

International audience; A novel dual electrochemical immunosensor was fabricated for the rapid and sensitive detection of enrofloxacin (EF) antibiotic in meat. Anti-quinolone antibody was immobilized onto screen-printed dual carbon electrodes via carbodiimide coupling. A new electrochemical probe was synthesized by conjugating difloxacin and aminoferrocene, whose oxidation was measured at +0.2 V vs. Ag/AgCl by differential pulse voltammetry. The detection principle was based on the competitive binding of this conjugate and free EF on immobilized antibodies. The proposed immunosensor allowed detection of EF at concentrations ranging from 0.005 µg.mL-1 to 0.01 µg.mL-1 with a detection limit of 0.003 µg.mL-1. The immunosensor was stable for at least 1 month at 4°C and displayed a good specificity for other fluoroquinolones. The new dual electrode design offered an improved accuracy as one electrode was used as negative control. The efficiency of the sensor and the adequacy of the extraction process were finally validated by detecting EF in different meat samples.

International audience; Background. Tropical coral reefs cover only ca. 0.1% of the Earth’s surface but host an outstanding biodiversity and provide important ecosystem services to millions of people living nearby. They are currently threatened by global (e.g., climate change) and local (e.g., chemical pollution) stressors that interact in different ways. While global stressors cannot be mitigated by local actions alone, local stressors can be reduced through ecosystem management. A systematic map on the impacts of chemicals arising from anthropogenic activities on tropical reef-building corals, which are the main engineer species of reef ecosystems, was published in 2021. This systematic map gathered an abundant literature (908 articles corresponding to 7937 studies), and identified four well-represented subtopics, amenable to relevant full syntheses. Here, we focused on one of the four subtopics: we aimed to systematically review the evidence on the ecotoxicological effects of chemicals on tropical reef-building corals.Methods. The evidence will be identified from the recent systematic map on the impacts of chemicals arising from anthropogenic activities on tropical reef-building corals. Especially, all studies in the map database corresponding to the knowledge cluster “evidence on the ecotoxicological effects of chemicals on corals” will be selected. To identify the evidence produced since then, a search update will be performed using a subset of the search string used for the systematic map, and titles, abstracts and full-texts will be screened according to the criteria defining the selected cluster of the map. In addition, as the eligibility criteria for the systematic review are narrower than those used to define the cluster in the systematic map, additional screening will be carried out. The included studies will then be critically appraised and a low, medium, or high risk of bias will be assigned to each study. Data will be extracted from studies and synthesised according to a strategy depending on the type of exposure and outcome. Synthesis will be mainly quantitative but also narrative, aiming to identify toxicity thresholds of chemicals for corals.

International audience; Background: Tropical coral reefs cover ca. 0.1% of the Earth's surface but host an outstanding biodiversity and provide important ecosystem services to millions of people living nearby. They are currently threatened by local stressors (e.g. nutrient enrichment and chemical pollution arising from poor land management, sewage effluents, agriculture, industry) and global stressors (mainly seawater warming and acidification, i.e. climate change). Global and local stressors interact in different ways, but the presence of one stressor often reduces the tolerance to additional stress. While global stressors cannot be mitigated solely by local actions, local stressors can be reduced through ecosystem management, therefore minimizing the impact of climate change on coral reefs. We systematically mapped the evidence of impacts of chemicals arising from anthropogenic activities on tropical reef-building corals, which are the main engineer species of reef ecosystems, to inform decision-makers on the available evidence on this topic.Methods: We searched the relevant literature using English terms combined in a tested search string in two publication databases (Scopus and Web Of Science Core Collection). The search string combined terms describing the population (tropical reef-building corals) and the exposure (chemicals). We searched for additional literature through three search engines, three dissertations repositories, 11 specialist websites, and through a call to local stakeholders. Titles, abstracts, and full-texts were successively screened using pre-defned eligibility criteria. A database of all studies included in the map with coded metadata was produced. The evidence was described and knowledge clusters and gaps were identifed through the distribution and frequency of studies into types of exposure and/or types of outcomes and/or types of study.Review findings: The initial searches identifed 23,403 articles which resulted in 15,177 articles after duplicate removal. Among them, 908 articles were retained after screening process, corresponding to 7937 studies (a study being the combination of a taxon, an exposure, and an outcome). Among these studies, 30.5% dealt with the impact of nutrient enrichment on corals while 25% concerned the impact of human activities without referenceto a chemical. The most measured outcomes were those related to the chemical concentration in corals (bioaccumulation, 25.8%), to coral physiology (16.9%), cover (14%), and mortality (9%). Half of the studies (48.4%) were experimental—the exposure was controlled by the researchers—and were conducted in laboratory conditions (39.4%) and in situ (9%). The most studied taxa, exposure, and outcomes were diferent between experimental andobservational studies.Conclusions: We identifed four well-represented subtopics that may be amenable to relevant full syntheses via systematic reviews: (1) evidence on bioaccumulation of chemicals by corals; (2) evidence on the efects of nutrient enrichment on corals; (3) evidence on the efects of human activities on corals; and (4) evidence on the ecotoxicological efects of chemicals on corals (except nutrient enrichment). The systematic map shows that corals in their natural environment can be exposed to many categories of chemicals, and that there is a complete gap in experimental research on the combined efects of more than two categories of chemicals. We therefore encourage research on this topic.

International audience; Sharka disease, caused by Plum pox virus (PPV), induces several changes in Prunus. In leaf tissues, the infection may cause oxidative stress and disrupt the photosynthetic process. Moreover, several defense responses can be activated after PPV infection and have been detected at the phytohormonal, transcriptomic, proteomic, and even translatome levels. As proposed in this review, some responses may be systemic and earlier to the onset of symptoms. Nevertheless, these changes are highly dependent among species, variety, sensitivity, and tissue type. In the case of fruit tissues, PPV infection can modify the ripening process, induced by an alteration of the primary metabolism, including sugars and organic acids, and secondary metabolism, including phenolic compounds. Interestingly, metabolomics is an emerging tool to better understand Prunus–PPV interactions mainly in primary and secondary metabolisms. Moreover, through untargeted metabolomics analyses, specific and early candidate biomarkers of PPV infection can be detected. Nevertheless, these candidate biomarkers need to be validated before being selected for a diagnostic or prognosis by targeted analyses. The development of a new method for early detection of PPV-infected trees would be crucial for better management of the outbreak, especially since there is no curative treatment.

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International audience; The bis-triazole ligand and its corresponding copper complexes were synthesized and characterized for the first time and proposed as new labels for the development of electrochemical aptasensors. The bis-triazole ligand was prepared from methyl 1,6-heptadiyne-4-carboxylate and 2-(azidomethyl)phenol using classical CuAAC in presence of different copper salts. The X-ray structure of bis-triazole showed a symmetry center (C1). UV-Vis and X-band EPR spectra showed that the coordination capacity of the bis-triazole ligand was improved in the presence of triethylamine due to deprotonation of the triazole and phenolate moieties. After complexation with copper, the obtained complex was successfully attached to an anti-estradiol aptamer through thiol-maleimide coupling, and the resulting labelled aptamer was immobilized on a carbon screen-printed electrode by carbodiimide coupling. The electrochemical response of the resulting sensor was shown to decrease in the presence of estradiol, demonstrating that the developed complexes can be applied for the development of aptasensors.

BACKGROUND: The occurrence of pharmaceutical compounds in wastewater has become a major concern for human health and the environment. Therefore, it is an important challenge to improve conventional wastewater treatment to remove these compounds. Coupling biological treatment with advanced oxidation technology has been widely studied in the literature, but only sequential associations of the two processes have been used. This study proposes an innovative concept based on a real integration of the photocatalytic oxidation process in a continuous recycling loop on a membrane bioreactor. The role of the oxidation here is not to completely degrade pharmaceuticals, but instead to oxidize them moderately to increase their biodegradability so that they can be eliminated by the biological process. RESULTS: Preliminary experiments on the oxidation process indicated that a flux density of 5 W m−2 was sufficient to increase biodegradability and decrease the toxicity of a cocktail of three pharmaceuticals. Then the performance of a 20-L continuous membrane bioreactor treating wastewater with seven pharmaceuticals, without and with pre-oxidation at 5 W m−2, were compared. Pre-oxidation increased the global removal for some recalcitrant pharmaceuticals (from 3% to 47% for diclofenac and from 1% to 44% for furosemide) without affecting either the removal of carbon, nitrogen or phosphorous by activated sludge, or of already highly removed pharmaceuticals. CONCLUSION: This work proves the feasibility of an innovative concept of a continuous hybrid process coupling a photocatalytic oxidation process and a membrane bioreactor for the treatment of pharmaceuticals in wastewater, with low cost and size. © 2020 Society of Chemical Industry (SCI)., This work was supported by the Program ‘SUDOE’ on the project Innovec'EAU 2016-2019 under award number SUDOE SOE1/P1/F0173. We thank R. Garcia and J. J. Huc for their help in designing and building the demonstrator, and Victor Pueyo for doing the analysis.

Maize cultivators often use β-triketone herbicides to prevent the growth of weeds in their fields. These herbicides target the 4-HPPD enzyme of dicotyledons. This enzyme, encoded by the hppd gene, is widespread among all living organisms including soil bacteria, which are considered as “non-target organisms” by the legislation. Within the framework of the pesticide registration process, the ecotoxicological impact of herbicides on soil microorganisms is solely based on carbon and nitrogen mineralization tests. In this study, we used more extensive approaches to assess with a lab-to-field experiment the risk of β-triketone on the abundance and the diversity of both total and hppd soil bacterial communities. Soil microcosms were exposed, under lab conditions, to 1× or 10× the recommended dose of sulcotrione or its commercial product, Decano®. Whatever the treatment applied, sulcotrione was fully dissipated from soil after 42 days post-treatment. The abundance and the diversity of both the total and the hppd bacterial communities were not affected by the herbicide treatments all along the experiment. Same measurements were led in real agronomical conditions, on three different fields located in the same area cropped with maize: one not exposed to any plant protection products, another one exposed to a series of plant protection products (PPPs) comprising mesotrione, and a last one exposed to different PPPs including mesotrione and tembotrione, two β-triketones. In this latter, the abundance of the hppd community varied over time. The diversity of the total and the hppd communities evolved over time independently from the treatment received. Only slight but significant transient effects on the abundance of the hppd community in one of the tested soil were observed. Our results showed that tested β-triketones have no visible impact toward both total and hppd soil bacteria communities.

International audience; Background: Tropical coral reefs cover ca. 0.1% of the Earth's surface but host an outstanding biodiversity and provide important ecosystem services to millions of people living nearby. However, they are currently threatened by both local (e.g. nutrient enrichment and chemical pollution of coastal reefs, arising from poor land management, agriculture and industry) and global stressors (mainly seawater warming and acidification, i.e. climate change). Global and local stressors interact together in different ways, but the presence of one stressor often reduces the tolerance to additional stress. While global stressors cannot be halted by local actions, local stressors can be reduced through ecosystem management, therefore minimizing the impact of climate change on reefs. To inform decision-makers, we propose here to systematically map the evidence of impacts of chemicals arising from anthropogenic activities on tropical reef-building corals, which are the main engineer species of reef ecosystems. We aim to identify the combinations of chemical and coral responses that have attracted the most attention and for which evidence can be further summarized in a systematic review that will give practical information to decision-makers. Methods: The systematic map will follow the Collaboration for Environmental Evidence Guidelines and Standards for Evidence Synthesis in Environmental Management. We will search the relevant literature using English terms combined in a tested search string in two publication databases (Web Of Science Core Collection and Scopus). The search string will combine terms describing the population (tropical reef-building corals) and the exposure (chemicals). We will supplement this literature with some more obtained through search engines, specialist websites, and through a call to local stakeholders. Titles, abstracts, and full-texts will then be successively screened using pre-defined eligibility criteria. A list of pre-defined variables will then be extracted from full-texts. Finally, a database of all studies included in the map with coded metadata will be produced. The evidence will be described in a map report with text, figures and tables, and a matrix showing the distribution and frequency of included study into types of exposure and types of outcomes will be computed to identify potential knowledge gaps and knowledge clusters.

Metallic complexes of macrocycles chelators 1,4,7-triazacyclononane-N,N,N-triacetic acid (NOTA) and 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) were synthetized with iron (III) giving Fe(III)-DOTA and Fe(III)-NOTA complexes. They were studied in comparison of ferricyanide and ferrocenemethanol on cyclic voltammetry with glassy carbon working electrode (GC) and screen-printed carbon electrode (SPCE). Diffusion coefficients and heterogeneous electron transfer rate constants were determined with Randles-Sevcik and Nicholson-Lavagnini methods. Using SPCE. The average values of diffusion coefficient and transfer rate constant were respectively of 1.34 × 10−6 cm2 s−1 and 1.01 × 10−3 cm s−1 for Fe(III)-DOTA, and 4.32 × 10−6 cm2 s−1 and 1.14 × 10−3 cm s−1 for Fe(III)-NOTA. Interestingly, characteristics of the synthetized complexes on SPCE compete advantageously with those of ferricyanide and ferrocenemethanol, making Fe(III)-DOTA and Fe(III)-NOTA potential markers for future biosensors development.

With the increasing incidence and prevalence of antibiotic contamination in animal-derived food and drug resistance around the world, early and specific detection of antibiotic residues has garnered significant attention. Herein, for the first time, we devise a facile, label free and portable aptasensor for quantitative determination of Kanamycin (KANA) by electrochemical impedance spectroscopy (EIS), which accompanying the assembly of in-vitro selected single strand DNA (ssDNA) anti-KANA-aptamer functionalized screen printed carbon electrodes (SPCEs) used as transducer. The target detection is based on specific recognition by KANA-aptamer covalently immobilized on SPCEs surface. The surface morphology and electrochemical properties of aptasensor were characterized using Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), atomic force microscopy (AFM), cyclic voltammetry (CV) and EIS. Under optimized experimental conditions, the devised aptasensor exhibited a dynamic range 1.2–600 ng mL−1 with linearity 1.2–75 ng mL−1 and limit of detection (LOD) 0.11 ng mL−1 (S/N = 3) of KANA. The developed aptasensor are endowed with a good selectivity and specificity to KANA without interference from competitive analogues (streptomycin and gentamicin). For practical application, the aptasensor performance was verified in spiked milk samples and the acceptable recovery percentage of 96.88–100.5% (%RSD = 4.56, n = 3) was obtained in milk samples.

The paper describes the development of an amperometric biosensor using Prussian Blue (PB) modified electrodes containing xanthine oxidase (XOD). The enzyme is immobilized by photo-polymerization into an azide-unit pendant water-soluble photopolymer (PVA-AWP). The parameters of the fabrication of the biosensor, XOD:PVA/AWP ratio, crosslinking irradiation time, and XOD charge, were optimized. Operational conditions for electrode preparation were defined as 1:2 ratio of XOD:PVA/AWP; exposure time to neon light of 30 min; pH = 7.5 at room temperature and enzymatic charge of 8 mU per electrode. The biosensors showed stable, fast, simple, selective, cost-effective and sensitive (-2.72E-8 A mol L-1), with a good linear range (1.0–75 μmol L-1), and respectively detection and quantification limits for antioxidants of 2.17, and 7.15 μmol L-1. The applicability of this biosensor was demonstrated by in vitro analysis of gallic acid as standard antioxidant and Amazonian fruits as natural sources.

International audience; This work presents the synthesis and characterization of salen/salan metal complexes for their future application as electrochemicallabels in affinity sensors. Due to its stability and electrochemical properties, an oxovanadium salan complex was selected andcoupled to an estradiol-specific aptamer. The response of the resulting aptasensor was shown to decrease with increasing estradiolconcentration.

International audience; Rapid detection of the foodborne pathogen Salmonella in food processing is of crucial importance to prevent food outbreaks and to ensure consumer safety. Detection and quantification of Salmonella species in food samples is routinely performed using conventional culture-based techniques, which are labor intensive, involve well-trained personnel, and are unsuitable for on-site and high-throughput analysis. To overcome these drawbacks, many research teams have developed alternative methods like biosensors, and more particularly aptasensors, were a nucleic acid is used as biorecognition element. The increasing interest in these devices is related to their high specificity, convenience, and relative rapid response. This review aims to present the advances made in these last years in the development of biosensors for the detection and the quantification of Salmonella, highlighting applications on meat from the chicken food chain.

One major concern associated with food safety is related to residual effects of antibiotics that are widely used to treat animals and result in antimicrobial resistance. Among different groups of antibiotic, the use of quinolones in livestock is of major concern due to the significance of these antimicrobial drugs for the treatment of a range of infectious diseases in humans. Therefore, it is desirable to develop reliable methods for the rapid, sensitive, and on-site detection of quinolone residue levels in animal-derived foods to ensure food safety. Sensors and biosensors are promising future platforms for rapid and on-site monitoring of antibiotic residues. In this review, we focus on recent advancements and modern approaches in quinolone sensors and biosensors.

RNA represents an extremely promising and yet challenging therapeutic target. Here, we report the design of a series of C-nucleosides as original RNA binders. Some of them bind strongly and selectively to A-site prokaryotic ribosomal RNA.

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International audience; Impact of leptospermone, a β-triketone bioherbicide, was investigated on the fungal community which supports important soil ecological functions such as decomposition of organic matter and nutrients recycling. This study was done in a microcosm experiment using two French soils, Perpignan (P) and Saint-Jean-de-Fos (SJF), differing in their physicochemical properties and history treatment with synthetic β-triketones. Soil microcosms were treated with leptospermone at recommended dose and incubated under controlled conditions for 45 days. Untreated microcosms were used as control. Illumina MiSeq sequencing of the internal transcribed spacer region of the fungal rRNA revealed significant changes in fungal community structure and diversity in both soils. Xylariales, Hypocreales, Pleosporales and Capnodiales (Ascomycota phyla) fungi and those belonging to Sebacinales, Cantharellales, Agaricales, Polyporales, Filobasidiales and Tremellales orders (Basidiomycota phyla) were well represented in treated soil microcosms compared to control. Nevertheless, while for the treated SJF a complete recovery of the fungal community was observed at the end of the experiment, this was not the case for the P treated soil, although no more bioherbicide remained. Indeed, the relative abundance of most of the saprophytic fungi were lower in treated soil compared to control microcosms whereas fungi from parasitic fungi included in Spizellomycetales and Pezizales orders increased. To the best of our knowledge, this is the only study assessing the effect of the bioherbicide leptospermone on the composition and diversity of the fungal community in soil. This study showed that leptospermone has an impact on α- and β-diversity of the fungal community. It underlines the possible interest of microbial endpoints for environmental risk assessment of biopesticide.

A quenching based apta-sensing platform was developed for the detection of Patulin. Three different aptamer sequences were studied to screen the aptamer with the maximum affinity towards Patulin. Carboxyfluorescein (CFL) was used as a fluorescent dye while –COOH functionalized multiwall carbon nanotubes (MWCNTs) were applied as novel nanoquenchers. Aptamer tagged at the 3′ end with 40 nucleotide bases exhibited the maximum affinity towards Patulin and caused substantial fluorescence recovery. Interestingly, the limit of detection (LOD) and limit of quantification (LOQ) were calculated as 0.13 μg L−1 and 0.41 μg L−1 respectively. Commonly occurring mycotoxins in food were also tested to confirm the selectivity of apta-assay. The developed apta-assay was applied to a spiked apple juice sample and toxin recoveries were observed ranging from 96% to 98% (n = 3). These results demonstrated the potential of the developed apta-assay for the selective detection and quantification of Patulin in food samples.

International audience; Biological and synthetic recognition elements are at the heart of the majority of modern bioreceptor assays. Traditionally, enzymes and antibodies have been integrated in the biosensor designs as a popular choice for the detection of toxin molecules. But since 1970s, alternative biological and synthetic binders have been emerged as a promising alternative to conventional biorecognition elements in detection systems for laboratory and field-based applications. Recent research has witnessed immense interest in the use of recombinant enzymatic methodologies and nanozymes to circumvent the drawbacks associated with natural enzymes. In the area of antibody production, technologies based on the modification of in vivo synthesized materials and in vitro approaches with development of “display “systems have been introduced in the recent years. Subsequently, molecularly-imprinted polymers and Peptide nucleic acid (PNAs) were developed as an attractive receptor with applications in the area of sample preparation and detection systems. In this article, we discuss all alternatives to conventional biomolecules employed in the detection of various toxin molecules We review recent developments in modified enzymes, nanozymes, nanobodies, aptamers, peptides, protein scaffolds and DNazymes. With the advent of nanostructures and new interface materials, these recognition elements will be major players in future biosensor development.

International audience; Ochratoxin A (OTA) is a carcinogenic mycotoxin that contaminates food such as cereals, wine and beer; therefore it represents a risk for human health. Consequently, the allowed concentration of OTA in food is regulated by governmental organizations and its detection is of major agronomical interest. In the current study we report the development of an electrochemical aptasensor able to directly detect trace OTA without any amplification procedure. This aptasensor was constructed by coating the surface of a gold electrode with a film layer of modified polypyrrole (PPy), which was thereafter covalently bound to polyamidoamine dendrimers of the fourth generation (PAMAM G4). Finally, DNA aptamers that specifically binds OTA were covalently bound to the PAMAM G4 providing the aptasensor, which was characterized by using both Atomic Force Microscopy (AFM) and Surface Plasmon Resonance (SPR) techniques. The study of OTA detection by the constructed electrochemical aptasensor was performed using Electrochemical Impedance Spectroscopy (EIS) and revealed that the presence of OTA led to the modification of the electrical properties of the PPy layer. These modifications could be assigned to conformational changes in the folding of the aptamers upon specific binding of OTA. The aptasensor had a dynamic range of up to 5 μg L−1 of OTA and a detection limit of 2 ng L−1 of OTA, which is below the OTA concentration allowed in food by the European regulations. The efficient detection of OTA by this electrochemical aptasensor provides an unforeseen platform that could be used for the detection of various small molecules through specific aptamer association.

Ochratoxin A (OTA), a widespread food contaminant, is considered as one of the most hazardous mycotoxins commonly occurring in beer. Herein, we describe a novel impedimetric aptasensor based on Pencil Graphite Electrodes (PGE) for the analysis of OTA. Taking advantage of its affordability and high active surface area, a PGE was modified with a specific aptamer, to achieve sensitive detection of OTA. This strategy relies on the target-induced increase in the electron transfer resistance (Rct) upon OTA recognition using ferro/ferricyanide as a redox probe. With the addition of OTA, the formation of OTA–aptamer complex resulted in an increase of Rct. The change of Rct strongly depends on OTA concentration, which is applied for mycotoxin quantification. An acceptable linear range was obtained from 0.1 to 2.0 ng mL−1 with a very good limit of detection as low as 0,1 ng mL−1. This simple-to-design aptasensor was successfully tested in spiked beer samples, with OTA concentrations in the range of 0.4–1.6 ng mL−1, attesting a recovery percentage of 93.4 ± 6.6%. It also showed a high level of stability and reproducibility thanks to the electro-grafting method via in-situ generation of 4-carboxyphenyl diazonium salts. This PGE-based platform is a versatile approach for the design of low-cost aptasensors for food safety control.

International audience; Cheliff River is the most important permanent river of North-west Algeria which plays an essential role for irrigation and drinking water supply, but suffers from high anthropogenic pressure. Multi-dimensional and multi-factorial aspects of water pollution in Cheliff River and its tributary Mina River were evidenced during two contrasting climatic seasons. Urban discharges were identified as a major source of water organic pollution. The inputs of untreated sewages were characterized by maximum concentrations of tryptophan-like (5.7 µmol l−1) and tyrosine-like (9.8 µmol l−1) compounds during the dry period, confirming these amino acids as fingerprints of untreated urban discharges. The synchronous monitoring and assessment of physicochemical parameters, fluorescent organic compounds and metallic elements of Cheliff River waters highlighted its global contamination, mainly in its downstream part. Cheliff River was mainly affected by organic pollution with maximum COD (1536 mg O2 l−1) and BOD5 (12 mg O2 l−1) during the wet period, and by metallic contamination with maximum Fe (287 ± 4.4 µg l−1) and Al (422.4 ± 9.4 µg l−1) during the dry period, exceeding the guideline limits. This chronic contamination was related to untreated domestic sewages, agricultural effluents and technical landfill center discharges in this area. Diffuse pollutions were also evidenced, which made the identification of different contamination sources complicated. Mina River was mostly affected by non-treated domestic sewages with maximum COD (3161 mg O2 l−1) during the wet period and maximum BOD5 (12 mg O2 l−1) during the dry period, exceeding the guideline limits. The correlation Li/Sr showed the contribution of natural influence from saline soils of Mina valley, particularly during the dry period.

International audience; Conventional agriculture still relics on the general use of agrochemicals (herbicides, fungicides and insecticides) to control various pests (weeds, fungal pathogens and insects), to ensure the yield of crop and to feed a constantly growing population. The generalized use of pesticides in agriculture leads to the contamination of soil and other connected environmental resources. The persistence of pesticide residues in soil is identified as a major threat for in-soil living organisms that are supporting an important number of ecosystem services. Although authorities released pesticides on the market only after their careful and thorough evaluation, the risk assessment for in-soil living organisms is unsatisfactory, particularly for microorganisms for which pesticide toxicity is solely considered by one global test measuring N mineralization. Recently, European Food Safety Authority (EFSA) underlined the lack of standardized methods to assess pesticide ecotoxicological effects on soil microorganisms. Within this context, there is an obvious need to develop innovative microbial markers sensitive to pesticide exposure. Biomarkers that reveal direct effects of pesticides on microorganisms are often viewed as the panacea. Such biomarkers can only be developed for pesticides having a mode of action inhibiting a specific enzyme not only found in the targeted organisms but also in microorganisms which are considered as "non-target organisms" by current regulations. This review explores possible ways of innovation to develop such biomarkers for herbicides. We scanned the herbicide classification by considering the mode of action, the targeted enzyme and the ecotoxicological effects of each class of active substance in order to identify those that can be tracked using sensitive microbial markers.

Electrochemical molecularly imprinted polymers (e-MIPs) were for the first time introduced in screen-printed carbon electrodes (SPCE) as the sensing element for the detection of an organic pollutant. To play this sensing role, a redox tracer was incorporated inside the binding cavities of a cross-linked MIP, as a functional monomer during the synthesis step. Ferrocenylmethyl methacrylate was used for this purpose. It was associated with 4-vinylpyridine as a co-functional monomer and ethylene glycol dimethacrylate as cross-linker for the recognition of the endocrine disruptor, Bisphenol A (BPA), as a target. Microbeads of e-MIP and e-NIP (corresponding non-imprinted polymer) were obtained via precipitation polymerization in acetonitrile. The presence of ferrocene inside the polymers was assessed via FTIR and elemental analysis and the polymers microstructure was characterized by SEM and nitrogen adsorption/desorption experiments. Binding isotherms and batch selectivity experiments evidenced the presence of binding cavities inside the e-MIP and its high affinity for BPA compared to carbamazepine and ketoprofen. e-MIP (and e-NIP) microbeads were then incorporated in a graphite-hydroxyethylcellulose composite paste to prepare SPCE. Electrochemical properties of e-MIP-SPCE revealed a high sensitivity in the presence of BPA in aqueous medium compared to e-NIP-SPCE with a limit of detection (LOD) of 0.06 nM. Selectivity towards carbamazepine and ketoprofen was also observed with the e-MIP-SPCE.

International audience; This paper presents for the first time the integration of a biosensor for the on-line, real-time monitoring of a photocatalytic degradation process. Paracetamol was used as a model molecule due to its wide use and occurrence in environmental waters. The biosensor was developed based on tyrosinase immobilization in a polyvinylalcohol photocrosslinkable polymer. It was inserted in a computer-controlled flow system installed besides a photocatalytic reactor including titanium dioxide (TiO2) as photocatalyst. It was shown that the biosensor was able to accurately monitor the paracetamol degradation with time. Compared with conventional HPLC analysis, the described device provides a real-time information on the reaction advancement, allowing a better control of the photodegradation process.

One of the main pursuits, yet most difficult, in monitoring studies is to identify the sources of environmental pollution. In this study, we have identified health-care facilities from south European countries as an important source of pharmaceuticals in the environment. We have estimated that compounds consumed in by the elderly and released from effluents of senior residences can reach river waters at a concentration higher than 0.01 ?g/L, which is the European Medicines Agency (EMA) threshold for risk evaluation of pharmaceuticals in surface waters. This study has been based on five health institutions in Portugal, Spain, and France, with 52 to 130 beds. We have compiled the pharmaceuticals dispensed on a daily base and calculated the consumption rates. From 54.9 to 1801 g of pharmaceuticals are consumed daily, with laxatives, analgesics, antiepileptics, antibiotics, and antidiabetic agents being the main drug families administered. According to excretion rates, dilution in the sewerage system, and elimination in wastewater treatment plants, macrogol, metformin, paracetamol, acetylcysteine, amoxicillin, and gabapentin, among others, are expected to reach river waters. Finally, we discuss the risk management actions related to the discharge of pharmaceuticals from senior residences to surface waters. info:eu-repo/semantics/acceptedVersion

International audience; The fate of benzo(a)pyrene (BaP), a ubiquitous contaminant reported to be persistent in the environment, is largely controlled by its interactions with the soil organic matter. In the present study, the spectral characteristics of fluorophores present in the physical fractions of the soil organic matter were investigated in the presence of pure BaP solution. After extraction of humic substances (HSs), and their fractionation into fluvic acid (FA) and humic acid (HA), two fluorescent compounds (C1 and C2) were identified and characterized in each physical soil fraction, by means of fluorescence excitation-emission matrices (FEEMs) and Parallel Factor Analysis (PARAFAC). Then, to each type of fraction having similar DOC content, was added an increasing volume of pure BaP solution in attempt to assess the behavior of BaP with the fluorophores present in each one. The application of FEEMs-PARAFAC method validated a three-component model that consisted of the two resulted fluorophores from HSs, FA and HA (C1 and C2) and a BaP-like fluorophore (C3). Spectral modifications were noted for components C2HSs (C2 in humic substances fraction) (λex/λem: 420/490-520 nm), C2FA (C2 in fulvic acid fraction) (λex/λem: 400/487(517) nm) and C1HA (C1 in humic acid fraction) (λex/λem: 350/452(520) nm). We explored the impact of increasing the volume of the added pure BaP solution on the scores of the fluorophores present in the soil fractions. It was found that the scores of C2HSs, C2FA, and C1HA increased when the volume of the added pure BaP solution increased. Superposition of the excitation spectra of these fluorophores with the emission spectrum of BaP showed significant overlaps that might explain the observed interactions between BaP and the fluorescent compounds present in SOM physical fractions.

International audience; In this report, a gold nanoparticle decorated single walled carbon nanotube (SWCNTs) nanocomposite was shown to possess synergistic intrinsic peroxidase like activity and enhanced affinity towards H2O2 oxidation. The gold nanoparticle decorated SWCNTs nanocomposite was characterized by high catalytic activity, enhanced stability from the gold nanoparticles and improved dispersion from the SWCNTs. Subsequently, this nanocomposite was proved to be a novel peroxidase mimetic with great potential to catalyze the oxidation of 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H2O2 to yield a blue colored product. As a proof of concept, the gold nanoparticle decorated SWCNTs composite was used as a robust nanoprobe for the detection of D-alanine with improved analytical characteristics. Taking into account the valuable intrinsic peroxidase activity of the nanohybrid, the present work may find widespread applications in the field of sensors and biosensors for diverse applications.

International audience; In this paper, we have reported a novel electrochemical aptamer–antibody based sandwich biosensor for the detection of lysozyme. In the sensing strategy, an anti-lysozyme aptamer was immobilized onto the carbon electrode surface by covalent binding via diazonium salt chemistry. After incubating with a target protein (lysozyme), a biotinylated antibody was used to complete the sandwich format. The subsequent additions of avidin-alkaline phosphatase as an enzyme label, and a 1-naphthyl phosphate substrate (1-NPP) allowed us to determine the concentration of lysozyme (Lys) via Differential Pulse Voltammetry (DPV) of the generated enzyme reaction product, 1-naphthol. Using this strategy, a wide detection range from 5 fM to 5 nM was obtained for a target lysozyme, with a detection limit of 4.3 fM. The control experiments were carried out by using bovine serum albumin (BSA), cytochrome c and casein. The results showed that the proposed biosensor had good specificity, stability and reproducibility for lysozyme analysis. In addition, the biosensor was applied for detecting lysozyme in spiked wine samples, and very good recovery rates were obtained in the range from 95.2 to 102.0% for lysozyme detection. This implies that the proposed sandwich biosensor is a promising analytical tool for the analysis of lysozyme in real samples.

International audience; Molecularly imprinted polymers (MIPs) for phosmet insecticide were synthesized by batch polymerization. The affinity of functional monomers to phosmet was tested using an original method involving an electrochemical biosensor based on acetylcholinesterase inhibition. It was demonstrated that association of phosmet with appropriate functional monomers resulted in a decrease of enzyme inhibition. Using this method, it was shown that N,N-methylenebis(acrylamide) displayed the highest interactions with phosmet using DMSO as solvent. These results were in good accordance with those obtained by conventional computational modeling. Molecularly imprinted polymers (MIPs) and non-imprinted polymers (NIPs) were synthesized and adsorption isotherms were studied to describe their interaction with phosmet. Freundlich isotherm was able to fit phosmet adsorption on MIPs with good agreement (R2 = 0.9). The pre-exponential factor KF determined for MIPs was 1.439mg(1-N)g-1LN, more that 10 times higher than for NIPs (0.125mg(1-N)g-1. LN), indicating an increase of binding sites number and average affinity.

This manuscript describes a portable and low cost fluorescence set-up to quantify the concentrations of Ochratoxin A (OTA) in real samples using a developed system. The detection through the set up consist of an ultraviolet light at 365 nm and a CMOS sensor controlled by an executable interface designed in MATLAB, with a time consumed from acquisition to processing to image display of 20 seconds. It is reported that OTA is naturally fluorescent, so it allows the user to get a photograph of the OTA under excitation conditions and process the image in order to predict the concentrations of the sample. To capture and process the image, in an automatically manner, the system was completely based on the Red, Green and Blue (RGB) components. For each concentration of the OTA, the R, G, B coordinates were obtained and plotted to quantify the mycotoxin presented in the sample. The linearity for OTA was obtained in the concentrations range of 5–40 μg/L. Immunoaffinity columns (IAC) and molecular imprinted polymer columns (MIP) were compared. The maximum recovery of 107.76% was recorded for 2 μg/L of OTA using IAC in beer samples. The obtained results were cross validated using chromatographic method HPLC. The developed setup is easy to use, economical and portable.

International audience; The-triketone herbicides are maize selective herbicides that have been largely applied in replacement of atrazine, banned in Europe in 2004. Their mode of action lays on the inhi- bition of the p-hydroxyphenylpyruvate dioxygenase (HPPD), a key enzyme of the carotenoid biosynthesis.In recent studies, we showed that within the soil bacterial community, many microorganisms possess a functional HPPD enzyme involved in tyrosine metabolism. These ”non-target or- ganisms” harbor the target of the-triketone herbicides and consequently may be affected in response to its exposure. From this point of view, the bacterial community harboring the hppd gene might be a relevant marker to assess the ecotoxicological impact of _-triketone herbicides on soil bacterial functional diversity.Within this context, the objective of our work is to check for the interest of hppd bacterial community as a marker of exposition and/or of impact sensitive to _-triketone herbicides. This will require the development of a molecular tool box to assess the abundance, activity and diversity of the hppd bacterial community in various arable soils exposed to _-triketone herbicides. The abundance and the activity of the hppd bacterial community will be mon- itored from the nucleic acids extracted directly from soils, and the diversity of the hppd community will be evaluated by a metagenomic study based on the high-throughput se- quencing of hppd amplicons.Our results will lead to the selection of a set of characteristic hppd sequences, allowing the development of hppd DNA chips to assess the ecotoxicological impact of _-triketone herbicides on soil microorganisms.

International audience; This paper describes for the first time the selection of aptamers selective to penicillin. Aptamers were selected using a specific process called Capture-SELEX (Systematic Evolution of Ligands by Exponential Enrichment). This technique is based on the selection of DNA aptamers using penicillin G in solution while the ssDNA library is fixed on a support. One aptamer showing a good affinity to penicillin was finally selected and tested in electrochemical sensor configuration, using electrochemical impedance spectroscopy as detection technique. The developed aptasensor allowed the detection of penicillin in a wide concentration range, comprised between 0.4 and 1000µgL-1 Such performance was compatible with milk analysis, as the maximum residue limit tolerated in this matrix is 4µgL-1. The selectivity of the developed sensor was also studied, showing that the sensor was also able to bind other beta-lactam antibiotics, although with a weaker affinity. Finally the sensor was used for detection of penicillin G in milk. It was shown that a simple sample treatment with isopropanol followed by filtration was sufficient to eliminate matrix effects, allowing the determination of penicillin in milk at concentrations compatible with legislation requirements.

This study presents a novel approach for assessing the risk of agrochemicals in soil microcosms through the use of non-targeted metabolomics. The metabolome of treated soils was extracted and tested through LCMS profiling in order to generate an "Environmental Metabolic Footprint" (EMF). A dynamic characterization of pollution biomarkers was obtained through a multivariate statistical analysis of EMF data, where our results show the possible evolution towards a state of resilience. The EMF methodology was applied to two β-triketone herbicides in soil microcosms: one natural, leptospermone, and one synthetic, sulcotrione. In spite of a four-fold higher application dose, leptospermone exhibited a lower resilience time than did sulcotrione (ca. 30 days vs ca. 45 days respectively).

International audience; In this study, a simple TAMRA (tetramethyl-6-carboxyrhodamine) quenching-based aptasensing platform was designed for the detection of aflatoxin B1 (AFB1). Here, we compared the analytical performance of two aptamer sequences: seqA and seqB. The AFB1 detection was based on the interactions of FAM (carboxyfluorescein)-labeled aptamer with TAMRA-labeled DNA complementary strand in the presence and absence of target analyte. Under optimized experimental conditions, TAMRA-labeled strand quenched the fluorescence response of FAM-labeled aptamer due to the noncovalent interaction between the two DNA strands. The binding of AFB1 induced the complex formation and weakened the interaction between FAM-labeled aptamer and TAMRA-labeled complementary strand, resulting in the fluorescence recovery. By using this principle concept, an assay was constructed for the detection of AFB1. The method exhibited good sensitivity, good selectivity with a limit of detection of 0.2 ng ml−1, and a wide linear range from 0.25 to 32 ng ml−1. For real sample application, the aptasensors were tested in beer and wine samples, with good recovery rates obtained for AFB1 detection.

International audience; A novel PCR-free DNA-based assay was developed for the detection of Vibrio spp. A sandwich hybridization format using an immobilized capture probe and a labeled signal probe was selected and combined with chemiluminescent method for the detection of the RNA target. In a first step, probes were validated using positive controls (PCs). A linearity was observed between 0.1 and 2.5 nM of PC, and detection limit was determined as 0.1 nM. In a second step, specificity was checked by using RNA extracted from a panel of 31 environmental bacterial strains. Detection limit of 5 ng μL−1 of total fragmented RNA was obtained, and the assay allowed a good discrimination between the 21 Vibrio and the 10 non-Vibrio strains tested. Finally, the DNA-based assay was successfully applied to analysis of spiked and natural environmental samples. Stability and analysis time of the DNA-based assay were also investigated to optimize working conditions. We demonstrated that microplates can be coated beforehand with capture probe and stored at 4 °C without any buffer in wells for at least 30 days. The use of the pre-made plates enables the assay to be completed in 2 h. The developed assay appeared as an interesting tool to determine the presence of bacteria in environmental samples

International audience; An ultra-sensitive screen-printed biosensor was successfully developed for phosmet detection in olive oil, based on a genetically-engineered acetylcholinesterase (AChE) immobilized in a azide-unit water-pendant polyvinyl alcohol (PVA-AWP)/Fe-Ni alloy nanocomposite. Fe-Ni not only allowed amplifying the response current but also lowering the applied potential from 80 mV to 30 mV vs Ag/AgCl. The biosensor showed a very good analytical performance for phosmet detection, with a detection limit of 0.1 nM. This detection limit is lower than the allowable concentrations set by international regulations. In addition to the good reproducibility, operational and storage stability, the developed biosensor was successfully used for the determination of phosmet in olive oil samples without any laborious pre-treatment. The phosmet recovery rate was about 96% after a simple liquid-liquid extraction.

A portable and low cost fluorescence set-up to quantify the concentrations of Ochratoxin A(OTA) in real samples was developed. The detection through the device consist of anultraviolet light at 365 nm and an photo detector or a CMOS sensor controlled by anexecutable interface designed in LabVIEW or MATLAB. It has been reported that OTA is naturally fluorescent, so it allows the user to get a UV LED to excite the sample, get a value involtage when a photodetector is employed or a photograph of the OTA under excitationconditions, and process that image in order to predict the concentrations of the sample. Tocapture and process the image, in an automatically manner, the system was completely basedon the Red, Green and Blue (RGB) components. The linearity for OTA obtained in the rangeof concentrations corresponds to 2-40 µg/L. Immunoaffinity columns (IAC) and molecularimprinted polymer columns (MIP) were used with cocoa, beer and wine samples. Theobtained results were cross-validated using chromatographic method such as HPLC and theFluoroskan equipment. The developed setup is easy to use, economical and portable. Besides,the use of new tendencies was included such as employ the smartphone to detect OTA and thecreation of an APP. Fluorescence image data from the smartphone camera are analyzed by apersonal computer and presented in RGB components, where the image is sent to thecomputer by WIFI and the smartphone is used as a power source too. Finally, an APP forandroid system was created to capture the image and provides the RGB values. At the end, theuse of image processing to quantify the OTA in real samples without incorporated IAC or MIPcolumns to extract the mycotoxin from a complex solution, employing colorimetric techniquesand color analysis.; Un appareil de mesure de la fluorescence, à faible coût et portable a été développé pour quantifier les concentrations d’Ochratoxine A (OTA) dans des échantillons réels. Le système est basé sur l’excitation par une UV-LED à 365 nm et un photo détecteur contrôlé par une interface dans LabVIEW. Aussi, une image capteur, CMOS, contrôlée par une interface conçue dans MATLAB. L’OTA est une molécule naturellement fluorescente. Après excitation par une UV-, l’image de la fluorescence émise est captée par une caméra et traitée en vue de la mesure de la concentration de l’OTA. Le système d’analyse a été basé sur les 3 composants rouge, vert et bleu (RGB, selon l'acronyme anglais). La gamme est linéaire entre de 2-40 µg/L. L’extraction de l’OTA est réalisée par des colonnes d'immuno affinité (IAC, selon l'acronymeanglais) et les colonnes à empreinte moléculaire (MIP, selon l'acronyme anglais) pour les échantillons de cacao, de la bière et du vin. Les résultats obtenus ont été validés par la méthode chromatographique (HPLC). L'appareil conçu est facile à utiliser, économique et portable. En outre, l'utilisation des nouvelles technologies a été inclus tels que l'emploi du smartphone pour détecter l'OTA et la création d'un APP. Des données d'image de fluorescence provenant de la caméra du smartphone et sont analysées par un ordinateur personnel et présentés dans les composantes RGB, où l'image est envoyée à l'ordinateur par WIFI et le téléphone intelligent est utilisé comme source d'énergie trop. Enfin, une APP pour le système Android a été créé pour capturer l'image et fournit les valeurs RGB. Enfin l'utilisation du traitement de l'image a été utilisée pour quantifier l'OTA dans les échantillons réels sans colonnes IAC ou MIP, employée pour extraire la mycotoxine. L’analyse a été réalisée par des techniques colorimétriques et d’analyse de la couleur.

International audience; A Surface Plasmon Resonance (SPR) sensor for the quantitation of lysozyme dimer in monomer-dimer mixtures, reaching a detection limit of 1.4 nM dimer, has been developed. The sensor is based on an aptamer which, although developed for the monomeric form, binds also the dimeric form but with a strikingly different kinetics. The aptasensor was calibrated using a dimer obtained by cross-linking. Sensorgrams acquired with the aptasensor in monomer-dimer mixtures were analysed using Principal Components Analysis and Multiple Regression to establish correlations with the dimer content in the mixtures. The method allows the detection of 0.1–1% dimer in monomer solutions without any separation. As an application, the aptasensor was used to qualitatively observe the initial stages of aggregation of lysozyme solutions at 60 °C and pH 2, through the variations in lysozyme dimer amounts. Several other methods were used to characterize the lysozyme dimer obtained by cross-linking and confirm the SPR results. This work highlights the versatility of the aptasensor, which can be used, by simply tuning the experimental conditions, for the sensitive detection of either the monomer or the dimer and for the observation of the aggregation process of lysozyme.

The last decade has witnessed an intensive research effort in the field of electrochemical sensors, with a particular focus on the design of amperometric biosensors for diverse analytical applications. In this context, nanomaterial integration in the construction of amperometric biosensors may constitute one of the most exciting approaches. The attractive properties of nanomaterials have paved the way for the design of a wide variety of biosensors based on various electrochemical detection methods to enhance the analytical characteristics. However, most of these nanostructured materials are not explored in the design of amperometric biosensors. This review aims to provide insight into the diverse properties of nanomaterials that can be possibly explored in the construction of amperometric biosensors.

A novel strategy based on direct electrochemistry of amino group on screen printed carbon electrode surface (SPCE) was purposed. The purposed method was employed for the label free detection of ochratoxin A (OTA). A long spacer arm of hexamethyldiamine was immobilized on SPCE via electrochemical oxidation of its terminal amino-group. The activated carboxy-aptamer was covalently linked to other amino terminal group of immobilized hexamethyldiamine. The designed immobilized macromolecules resulted in the formation of long clusters on SPCE surface, while aptamer acted as gate to block the entrance of these clusters. The aptamer gates were closed due to change in conformation of aptamer upon target analyte binding, decreasing the electrochemical signal. The decrease in electrochemical signal was used for the detection of target molecule.