Aptamer based electrochemical sensors for emerging environmental pollutants

International audienceEnvironmental contaminants monitoring is one of the key issues in understanding and managing hazards to human health and ecosystems. In this context, aptamer based electrochemical sensors have achieved intense significance because of their capability to resolve a potentially large number of problems and challenges in environmental contamination. An aptasensor is a compact analytical device incorporating an aptamer (oligonulceotide) as the sensing element either integrated within or intimately associated with a physiochemical transducer surface. Nucleic acid is well known for the function of carrying and passing genetic information, however, it has found a key role in analytical monitoring during recent years. Aptamer based sensors represent a novelty in environmental analytical science and there are great expectations for their promising performance as alternative to conventional analytical tools. This review paper focuses on the recent advances in the development of aptamer based electrochemical sensors for environmental applications with special emphasis on emerging pollutants

Biosensors: A Fast-Growing Technology for Pathogen Detection in Agriculture and Food Sector

Agriculture and food have a greater role to play in order to achieve sustainable development goals. Therefore, there is a need to put an end to the effect of pathogens on food quality and safety. Pathogens have been recognized as one of the major factors causing a reduction in profitable food production. The conventional methods of detecting pathogens are time-consuming and expensive for the farmers in rural areas. In view of this, this chapter reviews the biosensors that have been developed for the detection of biological hazards in food and agricultural sectors. This chapter also lays emphasis on the impact of nanotechnology on building a fast, reliable, more sensitive, accessible, user-friendly and easily adaptable technology for illiterate farmers in the rural communities. On the whole, we have addressed the past and most recent biosensors that could ensure the quick delivery of vision 2030 which aims to end hunger and poverty

Sensing Penicillin:Design and construction of Metabolite Biosensors

Since decades microorganisms are employed in industrial biotechnology for the production of valuable compounds, ranging from vitamins to antibiotics and bioplastics. Among the microorganisms used, filamentous fungi are of special interest for the production of very small molecules, so-called ‘secondary metabolites’, as they can have antibiotic, antifungal, or antitumor activity. In recent years, significant progress was made in the genome engineering of fungi, thereby allowing us to produce secondary metabolites at large scale. However, the detection of new secondary metabolites as well as the identification of single fungal cells that produce them in high amounts remains challenging and limits the overall production of fungal secondary metabolites. Molecular biosensors represent an interesting tool to approach this bottleneck, as they can specifically recognize small molecules in- and outside of cells and send a signal after detecting the target molecule. There are many different ways how to develop biosensors for the detection of metabolites and the number of working biosensors is increasing steadily, especially for well-studied microbes, such as the bacterium E. coli. However, there are no biosensors for the detection of secondary metabolites produced by filamentous fungi yet. In this thesis, we explored how biosensors can be constructed for the detection of the fungal metabolite penicillin G, one of the most important antibiotics worldwide. New strategies for the development of nucleic acid-, protein- and whole cell-based biosensors were investigated, thereby laying an important first step to improve the detection of fungal secondary metabolites in the future

Rapid Detection of Mycotoxin Contamination

A compilation of 12 original research articles and a review on the development of instrumental and immunoanalytical methods for mycotoxins; on the enhancement of sample preparation and selection to improve method applicability; and on practical applications of analytical methods in laboratory fungal cultures, cereal and feed samples, surface water (as a novel matrix of mycotoxins as emerging surface water contaminants), and during mycotoxin decontamination by bacteria. Target analyte mycotoxins include aflatoxins, deoxynivalenol, diacetoxyscirpenol, fumonisins, fusarenone-X, HT-2 toxins, nivalenol, ochratoxins, sterigmatocystin, T-2 toxin, and zearalenone

A Rapid and Ultra-sensitive Biosensing Platform based on Tunable Dielectrophoresis for Robust POC Applications

With the ongoing pandemic, there have been increasing concerns recently regarding major public health issues such as abuse of organophosphorus compounds, pathogenic bacterial infections, and biosecurity in agricultural production. Biosensors have long been considered a kernel technology for next-generation diagnostic solutions to improve food safety and public health. Significant amounts of effort have been devoted to inventing novel sensing mechanisms, modifying their designs, improving their performance, and extending their application scopes. However, the reliability and selectivity of most biosensors still have much to be desired, which holds back the development and commercialization of biosensors, especially for on-site and point-of-care (POC) usages. Herein, we introduce an innovative two-phase sensing strategy based on tunable AC electrokinetics and capacitive sensing. By dividing the detection process into a sensitivity-priority step and a selectivity-priority step, the specificity and sensitivity of a biosensor can be significantly improved. A capacitive POC aptasensor is fabricated for the implementation of the 2-phase detection and a quasi-single-cell level detection of limit together with an excellent selectivity is achieved simultaneously. The sensor is capable of handling real-world clinic samples without sophisticated pretreatment. Just after a simple one-step dilution, the developed sensor can detect bacteria no less than 2~3 bacteria/10 µL in raw milk samples within 100 s. Alongside whole bacteria detection, the biosensor can also detect endotoxin, the lipopolysaccharide, in bovine serum samples, with a limit of detection of 10 pg/mL. The biosensor is low-cost and easy to use. This work not only demonstrates a biosensor with significant advantages in sensitivity, selectivity and assay time but also opens up a new horizon for further research of all affinity-based biosensors

Detection, Control and Contamination of Mycotoxins

The objective of this collection is to illustrate the most recent research on the development of novel and/or rapid methods for mycotoxin determination, and to propose new strategies for monitoring and/or reducing mycotoxin contamination. Innovative sample preparation techniques or protocols and the possibility of multiclass mycotoxin detection will be very positively considered for possible inclusion in this Special Issue. Both methods based on (bio)sensors and chromatography with various detectors (including mass spectrometry) are welcome. Applications of already published methods on new matrices without any modification will not be accepted. However, extensive studies and monitoring on the spread of contamination through the food production chain could be of interest for this collection

Síntesis y caracterización de materiales nanoestructurados aplicados al diseño de sensores y biosensores electroquímicos

Tesis (Doctora en Ciencias Químicas) - - Universidad Nacional de Córdoba. Facultad de Ciencias Químicas, 2019En este trabajo de Tesis Doctoral se sintetizaron y caracterizaron nanoestructuras de magnetita, níquel y oro, las cuales se inmovilizaron en matrices de grafito o sustratos de oro con el objetivo de diseñar plataformas (bio)analíticas para el desarrollo de (bio)sensores electroquímicos. En el Capítulo 1 se presenta una introducción general acerca de la importancia de la utilización de sensores y biosensores en la química analítica y el diseño de nuevas plataformas mediante la incorporación de nanomateriales y biomoléculas. Se describen las características principales de las biomoléculas utilizadas en esta Tesis, enzimas y aptámeros. Además, se presentan distintas metodologías de inmovilización de biomoléculas en la construcción de biosensores. En el Capítulo 2 se describen las técnicas utilizadas y se discuten los fundamentos y conceptos necesarios para la compresión de los resultados presentados. También se detallan los materiales y metodologías utilizadas en este trabajo de Tesis. En el Capítulo 3 se reporta el desarrollo de un biosensor destinado a la cuantificación de glucosa basado en el uso de nanopartículas de magnetita recubiertas con carbono amorfo. Se discuten las propiedades electroquímicas de dichas nanopartículas, las ventajas de su incorporación junto a la enzima glucosa oxidasa en un electrodo compósito para el desarrollo de un biosensor para glucosa. Asimismo, se presenta la optimización de la plataforma a fin de obtener los parámetros analíticos óptimos para el mejor desempeño del biosensor. En el Capítulo 4 se presenta el desarrollo de una plataforma electroquímica basada en el empleo de nanohilos de níquel. Esta plataforma fue aplicada para la cuantificación de etanol, tomando ventaja de las propiedades electrocatalíticas del níquel hacia compuestos orgánicos en medio alcalino. Asimismo, se presentan los parámetros analíticos del sensor obtenido. El Capítulo 5 detalla la construcción de una superficie de oro modificada basada en la inmovilización de 4,4'-bifenilditiol y el posterior anclaje de nanopartículas anisotrópicas de oro o nanorods. La plataforma resultante se utilizó como punto de partida para la inmovilización de un aptámero específico para la detección de α-trombina humana. Adicionalmente, se presenta la optimización en cada etapa de la construcción de la plataforma diseñada para el mejor rendimiento analítico del aptasensor. En el Capítulo 6 se exponen las conclusiones generales del presente trabajo de Tesis Doctoral.202

Supramolecular Luminescent Sensors

There is great need for stand-alone luminescence-based chemosensors that exemplify selectivity, sensitivity, and applicability and that overcome the challenges that arise from complex, real-world media. Discussed herein are recent developments toward these goals in the field of supramolecular luminescent chemosensors, including macrocycles, polymers, and nanomaterials. Specific focus is placed on the development of new macrocycle hosts since 2010, coupled with considerations of the underlying principles of supramolecular chemistry as well as analytes of interest and common luminophores. State-of-the-art developments in the fields of polymer and nanomaterial sensors are also examined, and some remaining unsolved challenges in the area of chemosensors are discussed

Recent Advances and Achievements in Nanomaterial-Based, and Structure Switchable Aptasensing Platforms for Ochratoxin A Detection

Aptamer-based bioreceptors that can easily adopt their surroundings have captured the attention of scientists from a wide spectrum of domains in designing highly sensitive, selective and structure switchable sensing assays. Through elaborate design and chemical functionalization, numerous aptamer-based assays have been developed that can switch their conformation upon incubation with target analyte, resulting in an enhanced output signal. To further lower the detection limits to picomolar levels, nanomaterials have attracted great interest in the design of aptamer-based sensing platforms. Associated to their unique properties, nanomaterials offer great promise for numerous aptasensing applications. This review will discuss current research activities in the aptasensing with typical example of detection of ochratoxin A (OTA). OTA, a secondary fungal metabolite, contaminates a variety of food commodities, and has several toxicological effects such as nephrotoxic, hepatotoxic, neurotoxic, teratogenic and immunotoxic activities. The review will introduce advances made in the methods of integrating nanomaterials in aptasensing, and will discuss current conformational switchable design strategies in aptasensor fabrication methodologies