Identification and characterization of organic nanoparticles in food

A Comparative Review: Biological Safety and Sustainability of Metal Nanomaterials Without and with Machine Learning Assistance

In recent years, metal nanomaterials and nanoproducts have been developed intensively, and they are now widely applied across various sectors, including energy, aerospace, agriculture, industry, and biomedicine. However, nanomaterials have been identified as potentially toxic, with the toxicity of metal nanoparticles posing significant risks to both human health and the environment. Therefore, the toxicological risk assessment of metal nanomaterials is essential to identify and mitigate potential adverse effects. This review provides a comprehensive analysis of the safety and sustainability of metallic nanoparticles (such as Au NPs, Ag NPs, etc.) in key domains such as medicine, energy, and environmental protection. Using a dual-perspective analysis approach, it highlights the unique advantages of machine learning in data processing, predictive modeling, and optimization. At the same time, it underscores the importance of traditional methods, particularly their ability to offer greater interpretability and more intuitive results in specific contexts. Finally, a comparative analysis of traditional methods and machine learning techniques for detecting the toxicity of metal nanomaterials is presented, emphasizing the key challenges that need to be addressed in future research.

A Comprehensive Review of Biodegradable Polymer-Based Films and Coatings and Their Food Packaging Applications

Food sectors are facing issues as a result of food scarcity, which is exacerbated by rising populations and demand for food. Food is ordinarily wrapped and packaged using petroleum-based plastics such as polyethylene, polyvinyl chloride, and others. However, the excessive use of these polymers has environmental and health risks. As a result, much research is currently focused on the use of bio-based materials for food packaging. Biodegradable polymers that are compatible with food products are used to make edible packaging materials. These can be ingested with food and provide consumers with additional health benefits. Recent research has shifted its focus to multilayer coatings and films-based food packaging, which can provide a material with additional distinct features. The aim of this review article is to investigate the properties and applications of several bio-based polymers in food packaging. The several types of edible film and coating production technologies are also covered separately. Furthermore, the use of edible films and coatings in the food industry has been examined, and their advantages over traditional materials are also discussed.

Characterization of the selective binding of modified chitosan nanoparticles to Gram-negative bacteria strains

Chitosan is a nature-sourced polysaccharide widely used in numerous applications. The antibacterial potential of chitosan has attracted researchers to further develop and utilize this polymer for the formation of biocompatible antibacterial agents for both the food and healthcare industries. The tested hypothesis in this study is that modified N-alkylaminated chitosan nanoparticles (CNPs) have selective binding properties to Gram-negative bacteria strains that result in bacterial aggregation. Various bacterial strains were tested of five Gram-negative bacteria including Erwinia carotovora, Escherichia coli, Pseudomonas aeruginosa, Salmonella, and Serratia marcescens, as well as three Gram-positive bacteria strains including Bacillus licheniformis, Bacillus megaterium, and Bacillus subtilis. The fluorescence microscopy characterization showed that the presence of CNPs caused the aggregation of Escherichia coli bacteria cells, where modified CNPs with a shorter chain length of the substituent caused a higher aggregation effect. Moreover, it was found that the CNPs exhibited a selective binding behavior to Gram-negative as compared to Gram-positive bacteria strains, mainly to Escherichia coli and Salmonella. Also, the scanning electron microscopy characterization showed that CNPs exhibited selective binding to Gram-negative bacteria, which was especially understood when both Gram-negative and Gram-positive bacteria strains were within the same sample. In addition, the bacterial viability assay suggests that CNPs with a lower degree of substitution have a higher inhibitory effect on bacterial growth. CNPs with longer side chains had a less inhibitory effect on the bacterial growth of Gram-negative strains, where a concentration-dependent response pattern was only seen for the cases of Gram-negative strains, and not for the case of Gram-positive strain. To conclude, the further understanding of the selective binding of CNPs to Gram-negative bacteria strains may produce new opportunities for the discovery and characterization of effective antibacterial agents.

Study of the presence of micro- and nanoparticles in drinks and foods by multiple analytical techniques

A variety of food and drink samples (n = 21) were analyzed to evaluate the presence of (nano-) particles in their composition. After assessment of the sample pre-treatment step, a fast screening analysis was performed for drinks by Dynamic Light Scattering showing particles from 10 to 300 nm that could correspond to organic or metallic NPs. Metallic NPs were identified in foods by Single-Particle mode Inductively Coupled Plasma Mass Spectrometry and Asymmetrical Flow Field-Flow Fractionation coupled to Multiangle Laser Light Scattering and Inductively-Coupled Plasma Mass Spectrometry. The determination of Ti, Si and Ag concentration in the initial food suspensions, after filtration and centrifugal ultrafiltration enabled to estimate the ionic and nanoparticles content. Si-containing particles can be present in cappuccino powder as large aggregates and Si- and Al-containing particles in hot chocolate. Ti-containing NPs (80-200 nm) were found in chewing gum and Ag NPs in silver pearls (50-150 nm) used for decoration pastry.

Immobilised Electrocatalysts: Nafion Particles Doped with Ruthenium(II) Tris(2,2'-bipyridyl)

Nafion particles doped with ruthenium(II) tris(2,2'-bipyridyl) are synthesized by using a re-precipitation method. Characterization including SEM sizing and quantification of Ru(bpy)₃²⁺ in the Nafion particles using UV/Vis spectroscopy was conducted. The synthesized Ru-Nafion particles were investigated electrochemically at both ensemble and single particle levels. Voltammetry of the drop-cast Ru-Nafion particles evidences the successful incorporation of Ru(bpy)₃²⁺ into the Nafion particle but only a small fraction of the incorporated Ru(bpy)₃²⁺ was detected due at least in part to the formation of the likely agglomerated and irregular "mat" associated with the dropcast technique. In contrast, nano-impact experiments provided a quantitative determination of the amount of Ru(bpy)₃²⁺ in single Ru-Nafion particles. Finally, oxidation of solution-phase oxalate mediated by Ru(bpy)₃²⁺ within individual Nafion particles was observed, showing the electrocatalytic properties of the Ru-Nafion particles.

Nanotechnology in Food Packaging

Food packaging is an integral component of the global food supply chain, protecting food from dirt, chemical contaminants and microorganisms, and helping to maintain food quality during transport and storage. Much of this packaging relies on modern polymeric materials, which have been developed to help control the exposure of products to light, oxygen and moisture. These have the benefits of being lightweight, cost-effective, reusable, recyclable and resistant to chemical and physical damage. Although traditional polymeric materials can fulfill many of these requirements, efforts continue to maintain or improve packaging performance while reducing the use of raw materials, waste and costs. The use of nanotechnology to produce nanocomposite materials has great promise to improve the characteristics of food packaging, but many of the products are still in their infancy. Only a relatively small number of nanoenabled products have entered the market and many, but not all, occupy niche markets. This chapter briefly describes the areas where nanomaterials have been used in research and commercial products to improve mechanical and barrier properties and to create active and intelligent packaging materials. It also addresses the regulation of nanomaterials in food contact applications and migration when evaluating the safety of these materials.

Use of Foodomics for Control of Food Processing and Assessing of Food Safety

Food chain, food safety, and food-processing sectors face new challenges due to globalization of food chain and changes in the modern consumer preferences. In addition, gradually increasing microbial resistance, changes in climate, and human errors in food handling remain a pending barrier for the efficient global food safety management. Consequently, a need for development, validation, and implementation of rapid, sensitive, and accurate methods for assessment of food safety often termed as foodomics methods is required. Even though, the growing role of these high-throughput foodomic methods based on genomic, transcriptomic, proteomic, and metabolomic techniques has yet to be completely acknowledged by the regulatory agencies and bodies. The sensitivity and accuracy of these methods are superior to previously used standard analytical procedures and new methods are suitable to address a number of novel requirements posed by the food production sector and global food market.

Detection and Quantification of Single Engineered Nanoparticles in Complex Samples Using Template Matching in Wide-Field Surface Plasmon Microscopy

An ultrasensitive analytical method for direct detection of single nanoparticles in complex environment is described. The method relies on the wide-field surface plasmon microscopy (SPM). The suppression of matrix effects is achieved by image analysis based on the template matching. First, characteristic SPM images of nanoparticles are collected in aqueous suspensions. Then the detection of nanoparticles in complex environment is performed using template matching. Quantification and characterization of nanoparticles size was demonstrated at subppb level (∼100 pg/mL) in such complex media as wines, fruit juices, or cosmetic formulation. Visualization of the nanoparticles is performed in real time. The method does not require any sample pretreatment. If the minimally acceptable adsorption rate is defined as one nanoparticle to the whole sensor surface per few seconds, the working range of the method is ∼10⁶ to 10¹⁰ nanoparticles per mL.

Meeting the Needs for Released Nanomaterials Required for Further Testing-The SUN Approach

The analysis of the potential risks of engineered nanomaterials (ENM) has so far been almost exclusively focused on the pristine, as-produced particles. However, when considering a life-cycle perspective, it is clear that ENM released from genuine products during manufacturing, use, and disposal is far more relevant. Research on the release of materials from nanoproducts is growing and the next necessary step is to investigate the behavior and effects of these released materials in the environment and on humans. Therefore, sufficient amounts of released materials need to be available for further testing. In addition, ENM-free reference materials are needed since many processes not only release ENM but also nanosized fragments from the ENM-containing matrix that may interfere with further tests. The SUN consortium (Project on "Sustainable Nanotechnologies", EU seventh Framework funding) uses methods to characterize and quantify nanomaterials released from composite samples that are exposed to environmental stressors. Here we describe an approach to provide materials in hundreds of gram quantities mimicking actual released materials from coatings and polymer nanocomposites by producing what is called "fragmented products" (FP). These FP can further be exposed to environmental conditions (e.g., humidity, light) to produce "weathered fragmented products" (WFP) or can be subjected to a further size fractionation to isolate "sieved fragmented products" (SFP) that are representative for inhalation studies. In this perspective we describe the approach, and the used methods to obtain released materials in amounts large enough to be suitable for further fate and (eco)toxicity testing. We present a case study (nanoparticulate organic pigment in polypropylene) to show exemplarily the procedures used to produce the FP. We present some characterization data of the FP and discuss critically the further potential and the usefulness of the approach we developed.

Potential Health Impact of Environmentally Released Micro- and Nanoplastics in the Human Food Production Chain: Experiences from Nanotoxicology

High concentrations of plastic debris have been observed in the oceans. Much of the recent concern has focused on microplastics in the marine environment. Recent studies of the size distribution of the plastic debris suggested that continued fragmenting of microplastics into nanosized particles may occur. In this review we assess the current literature on the occurrence of environmentally released micro- and nanoplastics in the human food production chain and their potential health impact. The currently used analytical techniques introduce a great bias in the knowledge, since they are only able to detect plastic particles well above the nanorange. We discuss the potential use of the very sensitive analytical techniques that have been developed for the detection and quantification of engineered nanoparticles. We recognize three possible toxic effects of plastic particles: first due to the plastic particles themselves, second to the release of persistent organic pollutant adsorbed to the plastics, and third to the leaching of additives of the plastics. The limited data on microplastics in foods do not predict adverse effect of these pollutants or additives. Potential toxic effects of microplastic particles will be confined to the gut. The potential human toxicity of nanoplastics is poorly studied. Based on our experiences in nanotoxicology we prioritized future research questions.

Nano-food packaging: an overview of market, migration research, and safety regulations

Recently, food packages produced with nanoparticles, "nano-food packaging," have become more available in the current market. However, although the use of nanomaterials is increasing in food packaging applications, concern over toxicity affects consumer perceptions and acceptance. Quite a number of commercialized forms of nano-food packaging are coated or composited product with inorganic materials, for example, nanosilver and nanoclay as representative examples. Several studies have shown the possibility of nanomaterial migration from packaging or containers to foodstuff. The debate is still ongoing among researchers about the extent of migration and whether it is negligible and safe. Government agencies and stakeholders must hurry to determine use limitations and release conclusive legislation and regulations as soon as possible since nano-food packaging may have great impacts on human health. This paper aims to review the availability of nano-food packaging in the current market, report case studies on nanomaterial migration, and present the current status of safety regulations and management of nano-food packaging in leading countries across regions. This review should enable governments and researchers to develop further nanomaterial risk assessment studies.

Nanometrology and its perspectives in environmental research

OBJECTIVES

Rapid increase in engineered nanoparticles (ENPs) in many goods has raised significant concern about their environmental safety. Proper methodologies are therefore needed to conduct toxicity and exposure assessment of nanoparticles in the environment. This study reviews several analytical techniques for nanoparticles and summarizes their principles, advantages and disadvantages, reviews the state of the art, and offers the perspectives of nanometrology in relation to ENP studies.

METHODS

Nanometrology is divided into five techniques with regard to the instrumental principle: microscopy, light scattering, spectroscopy, separation, and single particle inductively coupled plasma-mass spectrometry.

RESULTS

Each analytical method has its own drawbacks, such as detection limit, ability to quantify or qualify ENPs, and matrix effects. More than two different analytical methods should be used to better characterize ENPs.

CONCLUSIONS

In characterizing ENPs, the researchers should understand the nanometrology and its demerits, as well as its merits, to properly interpret their experimental results. Challenges lie in the nanometrology and pretreatment of ENPs from various matrices; in the extraction without dissolution or aggregation, and concentration of ENPs to satisfy the instrumental detection limit.

Measurement Methods to Detect, Characterize, and Quantify Engineered Nanomaterials in Foods

This article is one of a series of 4 that reports on a task of the NanoRelease Food Additive project of the International Life Science Institute Center for Risk Science Innovation and Application to identify, evaluate, and develop methods that are needed to confidently detect, characterize, and quantify intentionally produced engineered nanomaterials (ENMs) released from food along the alimentary tract. This particular article focuses on the problem of detecting ENMs in food, paying special attention to matrix interferences and how to deal with them. In this review, an in-depth analysis of the literature related to detection of ENMs in complex matrices is presented. The literature review includes discussions of sampling methods, such as centrifugation and ENM extraction. Available analytical methods, as well as emerging methods, are also presented. The article concludes with a summary of findings and an overview of potential knowledge gaps and targets for method development in this area.

Analytical strategies for controlling polysorbate-based nanomicelles in fruit juice

This study focused on the detection and quantification of organic micelle-type nanoparticles (NPs) with polysorbate components (polysorbate 20 and polysorbate 80) in their micelle shells that could be used to load biologically active compounds into fruit juice. Several advanced analytical techniques were applied in the stepwise method development strategy used. In the first phase, a system consisting of ultrahigh-performance liquid chromatography employing a size exclusion column coupled with an evaporative light scattering detector (UHPLC-SEC-ELSD) was used for the fractionation of micelle assemblies from other, lower molecular weight sample components. The limit of detection (LoD) of these polysorbate micelles in spiked apple juice was 500 μg mL(-1). After this screening step, mass spectrometric (MS) detection was utilized to confirm the presence of polysorbates in the detected micelles. Two alternative MS techniques were tested: (i) ambient high-resolution mass spectrometry employing a direct analysis in real time ion source coupled with an Orbitrap MS analyzer (DART-Orbitrap MS) enabled fast and simple detection of the polysorbates present in the samples, with a lowest calibration level (LCL) of 1000 μg mL(-1); (ii) ultrahigh-performance reversed-phase liquid chromatography coupled with high-resolution time-of-flight mass spectrometry (UHPLC-HRTOF-MS) provided highly selective and sensitive detection and quantification of polysorbates with an LCL of 0.5 μg mL(-1).

Development and validation of single particle ICP-MS for sizing and quantitative determination of nano-silver in chicken meat

The application of nanomaterials is leading to innovative developments in industry, agriculture, consumer products, and food and related sectors. However, due to the special properties of these materials there are concerns about their safety, especially because of our limited knowledge of human health effects and the fact that constantly new nanomaterials and applications thereof are being produced. The development of analytical techniques is a key element to understand the benefits as well as the risks of the application of such materials. In this study, a method is developed and validated for sizing and quantifying nano-silver in chicken meat using single particle inductive coupled plasma mass spectrometry (ICP-MS). Samples are processed using an enzymatic digestion followed by dilution of the digest and instrumental analysis of the diluted digest using single particle ICP-MS. Validation of the method in the concentration of 5-25 mg/kg 60-nm silver nanoparticles showed good performance with respect to trueness (98-99% for size, 91-101% for concentration), repeatability (<2% for size, <11% for concentration), and reproducibility (<6% for size, <16% for concentration). The response of the method is linear, and a detection limit as low as 0.1 mg/kg can be obtained. Additional experiments showed that the method is robust and that digests are stable for 3 weeks at 4 °C. Once diluted for single particle ICP-MS analysis, the stability is limited. Finally, it was shown that nano-silver in chicken meat is not stable. Silver nanoparticles dissolved and were transformed into silver sulfide. While this has implications for the form in which nano-silver will be present in real-life meat samples, the developed method will be able to determine the presence and quantity of nanoparticle silver in such samples.

Characterization and preliminary toxicity assay of nano-titanium dioxide additive in sugar-coated chewing gum

Nanotechnology shows great potential for producing food with higher quality and better taste through including new additives, improving nutrient delivery, and using better packaging. However, lack of investigations on safety issues of nanofood has resulted in public fears. How to characterize engineered nanomaterials in food and assess the toxicity and health impact of nanofood remains a big challenge. Herein, a facile and highly reliable separation method of TiO2 particles from food products (focusing on sugar-coated chewing gum) is reported, and the first comprehensive characterization study on food nanoparticles by multiple qualitative and quantitative methods is provided. The detailed information on nanoparticles in gum includes chemical composition, morphology, size distribution, crystalline phase, particle and mass concentration, surface charge, and aggregation state. Surprisingly, the results show that the number of food products containing nano-TiO2 (<200 nm) is much larger than known, and consumers have already often been exposed to engineered nanoparticles in daily life. Over 93% of TiO2 in gum is nano-TiO2 , and it is unexpectedly easy to come out and be swallowed by a person who chews gum. Preliminary cytotoxicity assays show that the gum nano-TiO2 particles are relatively safe for gastrointestinal cells within 24 h even at a concentration of 200 μg mL(-1) . This comprehensive study demonstrates accurate physicochemical property, exposure, and cytotoxicity information on engineered nanoparticles in food, which is a prerequisite for the successful safety assessment of nanofood products.

Advanced Analytical Techniques for the Measurement of Nanomaterials in Food and Agricultural Samples: A Review

Nanotechnology offers substantial prospects for the development of state-of-the-art products and applications for agriculture, water treatment, and food industry. Profuse use of nanoproducts will bring potential benefits to farmers, the food industry, and consumers, equally. However, after end-user applications, these products and residues will find their way into the environment. Therefore, discharged nanomaterials (NMs) need to be identified and quantified to determine their ecotoxicity and the levels of exposure. Detection and characterization of NMs and their residues in the environment, particularly in food and agricultural products, have been limited, as no single technique or method is suitable to identify and quantify NMs. In this review, we have discussed the available literature concerning detection, characterization, and measurement techniques for NMs in food and agricultural matrices, which include chromatography, flow field fractionation, electron microscopy, light scattering, and autofluorescence techniques, among others.

Engineered nanoparticles and their identification among natural nanoparticles

The more nanotechnology develops, the more likely the release of engineered nanoparticles into the environment becomes. Due to a huge excess of natural nanoparticles, the identification and quantification of engineered nanoparticles pose a big challenge to analysts. Moreover, identification in a qualitative sense and quantification by mass concentration alone are not sufficient, because the potential environmental hazard arising from engineered nanoparticles is controlled by many other properties of the particles. We discuss the most important methods of fractionation and detection of both natural and engineered nanoparticles, with a focus on the chemical nature of the particles, particle concentration, and particle size. Analyses should not rely on only one method; instead, several complementary methods should, if possible, be used. Coupled techniques should be further developed and increasingly applied. Dedicated techniques that are tailored to the search for a particular sort of engineered nanoparticles are more promising than universal approaches that search for any engineered nanoparticles.