IAEAC – Nanotechnology for Food and Environmental Monitoring

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Thursday, April 21, 2022 1:00 pm EST
Organizer: Antje J. Baeumner, University of Regensburg

Monitoring food and environmental safety is a major analytical challenge due to the immensely complex and diverse matrices involved and the ever-growing number of contaminants of concern. Nanotechnological approaches demonstrate new detection strategies and principles, new sample preparation possibilities and exquisite sensitivity realizable for on-site application. In this symposium, the stage is first set introducing the complexity and need for the development of sustainable agriculture and food safety monitoring from a regulatory and funding agency perspective and demonstrating the grand advancements that nanotechnology can provide. This is followed by discussion of novel electrochemical and optical sensing platforms, new recognition strategies for highly specific chemical recognition, harnessing nanostructures for anti-fouling surfaces and studies on using nanomaterials to function as cell surrogate for rapid on-site pathogen detection.

Presentation 1
Nanotechnology for a Sustainable Agriculture and Food Monitoring
Hongda Chen, National Institute of Food and Agriculture – USDA
Agriculture and food systems are facing multiple dauting challenges including the demand of global food and nutrition security, consumer and industry supply, and circular economy toward sustainable future. Finite land, water and other natural resources of the Earth used for agricultural and food production and processing have already largely been exploited. Climate change and variability further exacerbate global agricultural production. Current practices, products and applications need to be much improved in terms of resource use efficiency to protect the environment, ensure safe and nutritious food supply, and sustain long term development. User-inspired ideas and transformative solutions emerged from multidisciplinary and transdisciplinary approaches will likely be better positioned to address system-framed challenging research questions and to lead successful inquiry. Nanoscale science, engineering and technology have enabled numerous advances that provide promises for sustainable agriculture and food system by the convergency of physical and biological sciences, biotechnology, information sciences, social sciences, and other disciplines. The presentation will focus on recent research advances in nanotechnology applications towards sustainable agriculture, food, and the environment. It will highlight some examples of nanotechnology R&D supported by USDA/National Institute of Food and Agriculture that address sustainability, vulnerability, health, and joy of living of society relevant to food and agricultural production, processing, and consumption. The efforts on advancing analytical science and developing new tools for supporting precision farming, promoting agricultural productivity, and ensuring food safety will be highlighted.

Presentation 2
Progress on the Electrochemical and Electrical Sensing of Pathogenic Bacteria Using Advanced Nanostructures
Christophe Ritzenthaler, CNRS
Despite the improvements of quarantine regulations and the diagnostics in the EU, the introduction and spread of pant pests\pathogens\diseases are constantly under globalization influence, through the intensified movement of people, plants, and products. Though the pest detection and surveillance methods are well established and widely available, these rely on elaborate procedures and highly equipped research laboratories. In this talk, I want to unveil simple protocols for direct testing and analysis at the farmers’ fields without the need of skilled technicians by developing smart, portable, and easy to handle nanometric devices. Electrochemical, electrical as well as plasmonic sensors and the use of graphene based nanostructures to enhance sensitivity will be elaborated. Some focus will be in ideal surface receptors for these sensors.

Presentation 3>
Innovative Strategies for Luminescent Sensing Coupled to Biological or Biomimetic Molecular Recognition: Applications in Food Mycotoxins Detection
Guillermo Orellana, Complutese University of Madrid
Selective molecular recognition elements are essential for the development of chemical sensors. A plethora of biomimetic recognition elements (e.g. molecularly imprinted polymers or MIPs, aptamers, peptides, etc.) have been used as an alternative to bioreceptors for food safety control. We have focused on the development of MIP-based sensing platforms for the detection of mycotoxins. Two different approaches were optimized for the analysis of tenuazonic acid (TeA). The first is based on porous MIP microspheres doped with a Eu(III) complex containing aqua (labile) ligands that, upon coordination to TeA, increase the rare earth typical luminescence at 615 nm (ex 337 nm).1 In the second approach, both the emission intensity and, for the first time, the emission lifetime were applied to the analysis of TeA. A novel trifunctional Ru(II) complex containing 2,2’-biimidazole as the TeA-binding moiety, and two polymerizable 2,2’-bipyridin-4,4’-diyldimethyl diacrylate ligands, was prepared and used for MIP synthesis. The latter, obtained in a core-shell nanoform on SiO2, allowed a significant reduction of the response time (60 min vs 5 s) and much lower detection limit (64 ng mL⁻1 vs 500 ng mL⁻1) than that of the first approach. Alternatively, gold nanoparticles (AuNPs) and a recombinant epitope-mimicking fluorescent fusion protein were used for the analysis of fumonisin B1 (FB1) mycotoxin in a homogeneous fluorescence quenching immunoassay.3 The assay was carried out in a single step without further washing to separate the unbound tracer. The method was applied to the analysis of FB1 in wheat extracts with a detection limit of 1.1 ng mL−1 and good selectivity. Acknowledgements. Work funded by the Spanish Ministry of Science and Innovation (grants RTI2018-096410-B-C21/C22). References 1 A. Rico-Yuste et al., Sensors Actuat. B: Chem. 2021, 329, 129256. 2 J. Quílez-Alburquerque et al., Polymers 2021, 230, 124041 3 R. Peltomaaet al., ACS Nano 2018, 12, 11333.

Presentation 4
Monitoring Plant Health with Near Infrared Fluorescent Nanosensors
Juan Pablo Giraldo, University of California, Riverside
Improving agricultural productivity requires innovative approaches for early detection of environmental and pathogen stresses responsible for crop plant losses, as well as novel high-throughput plant chemical phenotyping tools for developing stress tolerant plant varieties. Nanotechnology based sensors allow optical monitoring of plant biomolecules associated with health status via agricultural and phenotyping imaging devices. For example, near-infrared (nIR) fluorescent single-walled carbon nanotubes (SWCNTs) interfaced with plants report hydrogen peroxide (H2O2), a key signaling molecule associated with the onset of plants stress. The sensor nIR fluorescence response (>900 nm) is quenched by H2O2 with selectivity against other stress-associated signaling molecules and within the plant physiological range. In vivo remote nIR imaging of H2O2 sensors enables optical monitoring of plant health in response to stresses including UV-B light, high light, and pathogen-related peptides, but not mechanical leaf wounding. The sensor’s high biocompatibility was indicated by similar leaf cell death (<5%) and photosynthetic rates compared to controls without SWCNT. SWCNT also act as sensors for plant biomolecules associated with pathogen stress including polyphenols, secondary metabolites used for chemical defense against pathogens. Binding of different polyphenols both red-shift (up to 20 nm) and quench the fluorescence emission of SWCNT in a concentration dependent manner that reports the total polyphenol content. These sensors allow in vivo remote chemical imaging of pathogen-induced polyphenol release from roots and visualization of polyphenol-based plant defense response in real time. Optical nanosensors that report early signs of stress will improve our understanding of plant stress communication and precision agriculture, while providing novel tools for plant phenotyping applications aimed at developing crop plants with optimized stress responses.

Presentation 5
Nanovesicles as Cell Surrogate for the Detection of Hemolytic Bacteria in Visual and Electrochemical POCT Strategies
Antje J. Baeumner, University of Regensburg
Streptococci are Gram-positive bacteria which can cause various human diseases and are characterized based on their ability of erythrocyte lysis using blood agar plates, sub-classifying them into alpha, beta and gamma hemolytic bacteria, causing partial, complete or no lysis of erythrocytes, respectively. Most beta-hemolytic bacteria are pathogenic, the most prominent being Streptococcus pyogenes, often referred to as Group A streptococcus (GAS). It causes mild to severe infections of skin, soft tissues, joints and the lower respiratory system. Scarlet fever remains a serious childhood disease and even antibiotic treatment did not decrease in several developed countries. Millions of infections are caused by S. pyogenes each year with approximately 1100 to 1600 death per year and substantial costs for health systems. Even today, the 1903 invented, blood agar plates are the gold standard for the diagnosis of S. pyogenes in throat swab samples. Being not timely enough to supporting antibiotic treatment decisions it is yet inly used to confirm negative rapid antigen detection tests. We have hence investigated the use of nanomaterials to develop a point-of-care (POC) ready sensor that can quickly, reliably and sensitively detect hemolytic bacteria that does not rely on blood-agar plates. Here, liposomes embedding an electrochemical marker or a colorimetric marker were designed to be stealth in bacterial culture media as well as be highly sensitive toward the hemolytic activity of S. pyogenes. Laser-induced graphene (LIG) electrodes were designed as transducer and visual lateral flow strategies were used respectively. In this presentation, we will discuss advantages afforded by the nanomaterials and demonstrate how 100 colony forming units (CFU) can be detected within an easy mix and wait strategy.

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