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The cultivation of genetically modified organisms (GMO) continues to expand worldwide. Still, many consumers express concerns about the use of GMO in food or feed, and many countries have legislated on labelling systems to indicate the presence of GMO in commercial products. To deal with the increased number of GMO events and to address related regulations, alternative detection methods for GMO inspection are required. In this work, a genosensor based on Surface Plasmon Resonance under continuous flow was developed for the detection and quantification of a genetically modified soybean (event GTS 40-3-2). In a single chip, the simultaneous detection of the event-specific and the taxon-specific samples were achieved, whose detection limits were 20 pM and 16 pM, respectively. The reproducibility was 1.4%, which supports the use of the chip as a reliable and cost-effective alternative to other DNA-based techniques. The results indicate that the proposed method is a versatile tool for GMO quantification in food and feed samples. [ABSTRACT FROM AUTHOR]

The main goal of food safety assessment is to provide reliable information on the identity and composition of food and reduce the presence of harmful components. Nowadays, there are many countries where rather than the presence of pathogens, common public concerns are focused on the presence of hidden allergens, fraudulent practices, and genetic modifications in food. Accordingly, food regulations attempt to offer a high level of protection and to guarantee transparent information to the consumers. The availability of analytical methods is essential to comply these requirements. Protein-based strategies are usually employed for this purpose, but present some limitations. Because DNA is a more stable molecule, present in most tissues, and can be amplified, there has been an increasing interest in developing DNA-based approaches (polymerase chain reaction, microarrays, and genosensors). In this regard, electrochemical genosensors may play a major role in fulfilling the needs of food industry, such as reliable, portable, and affordable devices. This work reviews the achievements of this technology applied to allergen detection, species identification, and genetically modified organisms testing. We summarized the legislative framework, current design strategies in sensor development, their analytical characteristics, and future prospects. [ABSTRACT FROM PUBLISHER]

Despite having been underappreciated in favor of their protein-coding counterparts for a long time, long noncoding RNAs (lncRNAs) have emerged as functional molecules, which defy the central dogma of molecular biology, with clear implications in cancer. Altered expression levels of some of these large transcripts in human body fluids have been related to different cancer conditions that turns them into potential noninvasive cancer biomarkers. In this review, a brief discussion about the importance and current challenges in the determination of lncRNAs associated to cancer is provided. Different electrochemical nucleic acid-based strategies for lncRNAs detection are critically described. Future perspectives and remaining challenges for the practical implementation of these methodologies in clinical medicine are also discussed. [ABSTRACT FROM AUTHOR]

The detection of bacterial pathogens may be accomplished through their genome material. With that aim, current methods usually rely on polymerase chain reaction (PCR) amplifications, which are time consuming and require specialist equipment. Here, we optimized an on‐chip isothermal recombinase polymerase amplification (RPA) with chronoamperometric detection, which could be run with simple equipment. A short thiol‐modified oligonucleotide, complementary to a fragment of bipA gene of Salmonella spp. is chemisorbed onto the gold chip surface together with p‐aminothiophenol as a blocking agent. Remarkably, we demonstrate that, in the presence of Salmonella genome, this oligonucleotide, acting as a primer in RPA, is directly elongated on the surface, copying the genome and giving rise to an on‐surface enzyme‐tagged dsDNA. After 30 min of isothermal amplification, the chronoamperometric signal, related to one of the products of the enzyme reaction, increased with the amount of Salmonella genome, which allowed the detection of 105 copies. The results of this study may be of general utility in the design of sensors for detecting other bacteria. Under the influence: The mechanism for the selective and isothermal amplification with electrochemical detection of Salmonella genome on gold chips is investigated. The recombinase‐polymerase reaction takes place directly on the surface, elongating the anchored primer, which enables the detection of 105 genome units. [ABSTRACT FROM AUTHOR]

Abstract: Herein, we show the feasibility of using deep eutectic solvents as a faster way of selecting aptamers targeting poorly water‐soluble species. This unexplored concept is illustrated for gluten proteins. In this way, aptamer‐based gluten detection can be performed directly in the extraction media with improved detectability. We envision deep implications for applications not only in food safety control but also in biomedicine. [ABSTRACT FROM AUTHOR]

The InCl3-catalyzed reaction of ferrocene with orthohydroxybenzyl alcohols is reported and represents a convenient route for the synthesis of ferrocenyl phenols. This carbon–carbon bond forming process is believed to proceed through an ortho-quinone methide intermediate that can be interceptedby ferrocene through a Friedel–Crafts-type process. Preliminary cytotoxic screening carried out on several cancer cell lines revealed that some of the compounds exhibit moderate cytotoxicity [ABSTRACT FROM AUTHOR]

The design of screening methods for the detection of genetically modified organisms (GMOs) in food would improve the efficiency in their control. We report here a PCR amplification method combined with a sequence-specific electrochemical genosensor for the quantification of a DNA sequence characteristic of the 35S promoter derived from the cauliflower mosaic virus (CaMV). Specifically, we employ a genosensor constructed by chemisorption of a thiolated capture probe and p-aminothiophenol gold surfaces to entrap on the sensing layer the unpurified PCR amplicons, together with a signaling probe labeled with fluorescein. The proposed test allows for the determination of a transgene copy number in both hemizygous (maize MON810 trait) and homozygous (soybean GTS40-3-2) transformed plants, and exhibits a limit of quantification of at least 0.25% for both kinds of GMO lines. [ABSTRACT FROM AUTHOR]

Celiac disease is a lifelong autoimmune disorder triggered by foods containing gluten, the storage protein in wheat, rye, and barley. The rapidly escalating number of patients diagnosed with this disease poses a great challenge to both food industry and authorities to guarantee food safety for all. Therefore, intensive efforts are being made to establish minimal disease-eliciting doses of gluten and consequently to improve gluten-free labeling. These efforts depend to a high degree on the availability of methods capable of detecting the protein in food samples at levels as low as possible. Current analytical approaches rely on the use of antibodies as selective recognition elements. With limited sensitivity, these methods exhibit some deficiencies that compromise the accuracy of the obtained results. Aptamers provide an ideal alternative for designing biosensors for fast and selective measurement of gluten in foods. This article highlights the challenges in gluten detection, the current status of the use of aptamers for solving this problem, and what remains to be done to move these systems into commercial applications. [ABSTRACT FROM AUTHOR]

Current EU regulations on the mandatory labeling of genetically modified organisms (GMOs) with a minimum content of 0.9% would benefit from the availability of reliable and rapid methods to detect and quantify DNA sequences specific for GMOs. Different genosensors have been developed to this aim, mainly intended for GMO screening. A remaining challenge, however, is the development of genosensing platforms for GMO quantification, which should be expressed as the number of event-specific DNA sequences per taxon-specific sequences. Here we report a simple and sensitive multiplexed electrochemical approach for the quantification of Roundup-Ready Soybean (RRS). Two DNA sequences, taxon (lectin) and event-specific (RR), are targeted via hybridization onto magnetic beads. Both sequences are simultaneously detected by performing the immobilization, hybridization and labeling steps in a single tube and parallel electrochemical readout. Hybridization is performed in a sandwich format using signaling probes labeled with fluorescein isothiocyanate (FITC) or digoxigenin (Dig), followed by dual enzymatic labeling using Fab fragments of anti-Dig and anti-FITC conjugated to peroxidase or alkaline phosphatase, respectively. Electrochemical measurement of the enzyme activity is finally performed on screen-printed carbon electrodes. The assay gave a linear range of 2–250 pM for both targets, with LOD values of 650 fM (160 amol) and 190 fM (50 amol) for the event-specific and the taxon-specific targets, respectively. Results indicate that the method could be applied for GMO quantification below the European labeling threshold level (0.9%), offering a general approach for the rapid quantification of specific GMO events in foods. [ABSTRACT FROM AUTHOR]

Celiac disease represents a significant public health problem in large parts of the world. A major hurdle in the effective management of the disease by celiac sufferers is the sensitivity of the current available methods for assessing gluten contents in food. In response, we report a highly sensitive approach for gluten analysis using aptamers as specific receptors. Gliadins, a fraction of gluten proteins, are the main constituent responsible for triggering the disease. However, they are highly hydrophobic and large molecules, regarded as difficult targets for in vitro evolution of aptamers without nucleobase modification. We describe the successful selection of aptamers for these water insoluble prolamins that was achieved choosing the immunodominant apolar peptide from a2-gliadin as a target for selection. All aptamers evolved are able to bind the target in its native environment within the natural protein. The best nonprotein receptor is the basis for an electrochemical competitive enzyme-linked assay on magnetic particles, which allows the measurement of as low as 0.5 ppb of gliadin standard (0.5 ppm of gluten). Reference immunoassay for detecting the same target has a limit of detection of 3 ppm, 6 times less sensitive than this method. Importantly, it also displays high specificity, detecting the other three prolamins toxic for celiac patients and not showing cross-reactivity to nontoxic proteins such as maize, soya, and rice. These features make the proposed method a valuable tool for gluten detection in foods. [ABSTRACT FROM AUTHOR]

Ensuring food safety is nowadays a top priority of authorities and professional players in the food supply chain. One of the key challenges to determine the safety of food and guarantee a high level of consumer protection is the availability of fast, sensitive and reliable analytical methods to identify specific hazards associated to food before they become a health problem. The limitations of existing methods have encouraged the development of new technologies, among them biosensors. Success in biosensor design depends largely on the development of novel receptors with enhanced affinity to the target, while being stable and economical. Aptamers fulfill these characteristics, and thus have surfaced as promising alternatives to natural receptors. This Review describes analytical strategies developed so far using aptamers for the control of pathogens, allergens, adulterants, toxins and other forbidden contaminants to ensure food safety. The main progresses to date are presented, highlighting potential prospects for the future. [ABSTRACT FROM AUTHOR]

Abstract: The design and performance of an inhibition assay for the electrochemical detection of tobramycin is reported. This platform uses a monovalent system for introducing the enzyme conjugate on a tagged-aptamer that specifically recognizes the aminoglycoside antibiotic tobramycin. Compared with multivalent systems such as biotin–streptavidin, the sensitivity is greatly improved reducing the limit of detection from 5μM to 0.1μM in aqueous solution. This labeling strategy along with the use of a nuclease-resistant RNA aptamer allowed the determination of tobramycin in pre-treated human serum samples within the therapeutic range, using magnetic microparticles as a solid support for the aptassay, and differential pulse voltammetry as detection technique. [Copyright &y& Elsevier]

A magnetic microsphere-based hybridization assay for the electrochemical detection of pathogen-specific DNA sequences is reported. Enzyme-linked sandwich hybridization assays with different tags (biotin, fluorescein or digoxigenin) and enzyme conjugates (streptavidin-alkaline phosphatase, streptavidin-peroxidase, antifluorescein-peroxidase or antidigoxigenin-peroxidase) are comparatively evaluated. Sensitivity and limit of detection depend on both the choice of the enzyme and the tag. The highest sensitivity and lowest limit of detection were obtained when antibody Fab fragments conjugated to peroxidase were used as reporter molecule. The digoxigenin system yields the lowest detection limit, mainly due to producing much lower background signals. [ABSTRACT FROM AUTHOR]