Determination of silver in nano-plastic food packaging by microwave digestion coupled with inductively coupled plasma atomic emission spectrometry or inductively coupled plasma mass spectrometry

Quantification of silver in several samples using a new ionophore polymer membrane as an optical sensor

Growing concerns about the possible toxicity of silver to aquatic organisms, bacteria, and humans have led to newly issued regulations by the United States Environmental Protection Agency (US EPA) and the Food and Drug Administration (FDA) regarding the use of silver. However, the increase in bacterial resistance to antibiotics has led to a resurgence in the use of silver as a biocidal agent in applications ranging from washing machine additives to the drinking water treatment system on the International Space Station (ISS). For Ag+ ion detection, a highly sensitive and reversible optical sensor has been established. The optode relies on a novel Schiff base, namely 2-[(benzo[d]thiazol-2-ylimino)methyl]phenol (BTMP) immobilized within PVC film and also incorporated with tris(2-ethylhexyl)phosphate (TEHP) and Aliquat 336 as an ion carrier. Under optimum conditions (i.e. pH 8.5), the proposed sensor displayed a linear response to Ag+ over 4.8 × 10-9 to 1.0 × 10-5 M (0.8494-1698.7 μg L-1) with limits of detection and quantification of 1.5 × 10-9 and 4.8 × 10-9 M (0.2548 and 0.8494 μg L-1), respectively. The sensor's response time was found to be 8.0 min. The sensor was applied successfully to determine Ag+ ion in some real samples, including food, biological, water, and environmental samples.

Incorporation of silver nanoparticles into active antimicrobial nanocomposites: Release behavior, analyzing techniques, applications and safety issues

Employing new strategies to develop novel composite systems has become a popular area of interest among researchers. Raising people's awareness and their attention to the health and safety issues are key parameters to achieve this purpose. One of the recommended strategies is the utilization of nanoparticles within the matrix of composite materials to improve their physical, mechanical, structural and antimicrobial characteristics. Silver nanoparticles (Ag NPs) have attracted much attention for nanocomposite applications mainly due to their antimicrobial characteristics. Herein, the current review will focus on the different methods for preparing antimicrobial nanocomposites loaded with Ag NPs, the release of Ag NPs from these nanostructures in different media, analyzing techniques for the evaluation of Ag release from nanocomposites, potential applications, and safety issues of nanocomposites containing Ag NPs. The applications of Ag NPs-loaded nanocomposites have been extensively established in food, biomedical, textile, environmental and pharmacological areas mainly due to their antibacterial attributes. Several precautions should be addressed before implementation of Ag NPs in nanocomposites due to the health and safety issues.

Nano-enabled, antimicrobial toothbrushes - How physical and chemical properties relate to antibacterial capabilities

Over the past two decades, Ag and Zn nanoparticles have been integrated into various consumer products as a biocide. While some nano-enabled consumer products have been shown to have antibacterial properties, their antibacterial efficacy as well as the human and environmental health outcomes are not fully known. In this study, we examine a nanoparticle-enabled product that also serves as a conduit for human exposure to bacteria: toothbrushes. We utilize a combination of chemical analyses, laboratory experiments, and microscopy to characterize the nano-enabled toothbrush bristles. Our analysis showed the majority of measured Ag and Zn particles ranged from approximately 50 to 100 nm in size and were located on the surface and within bristles. During simulated brushing, antimicrobial bristles released both Ag and Zn, the majority of which was released in particulate form. While our results demonstrate that antimicrobial bristles have enhanced bactericidal properties compared to control samples, we also show that the surface topography influences nanoparticle retention, microbial adhesion, and bactericidal activity. We thus conclude that Ag or Zn content alone is insufficient to predict antimicrobial properties, which are further governed by the bioavailability of Ag or Zn at the bristle surface.

Nanoplastics in the oceans: Theory, experimental evidence and real world

This review critically analyses >200 papers collected by searching on Pubmed the word "nanoplastics", a group of emerging contaminants which are receiving growing attention. The present review intends to provide an overview of current knowledge on nanoplastic pollution starting with the theory of polymer degradation, passing to laboratory confirmation of nanoplastic formation and ending with the possible occurrence in sea water samples. Most of the observations proposed focus the attention on polystyrene (PS) because the majority of research knowledge is based on this polymer. Moreover, we thoroughly describe what effects have been observed on different organisms tested in controlled conditions. Nanoplastics formation, fate and toxicity seem to be a very dynamic phenomenon. In light of this, we identify some aspects retained crucial when an ecotoxicological study with nanoplastics is performed and which elements of nanoplastics toxicity could be deeper covered.

Direct screening of food packaging materials for post-polymerization residues, degradation products and additives by liquid extraction surface analysis nanoelectrospray mass spectrometry (LESA-nESI-MS)

Materials in direct contact with food should be monitored for the presence of species able to migrate into food. A direct method based on liquid extraction surface analysis nanoelectrospray mass spectrometry (LESA-nanoESI-MS) was developed for the analysis of the migrating species from a polymer film. Different types of molecules: post-polymerization residues, degradation products (oligomers resulting from polymer recycling, products of polymer oxidative degradation) and anti-oxidant additives (vitamin E) were demonstrated to be detected and identified, and determined quantitatively if relevant calibration standards are available. The method was validated by a comparison a standard method based on with bulk extraction mass spectrometry. It offers considerable advantages over the latter in terms of drastically reduced analysis time and solvent consumption. Also, LESA-nanoESI-MS produced simpler spectra (limited to compounds able to migrate into food) than Direct Analysis in Real Time (DART).

Nanomaterials in Food Products: A New Analytical Challenge

This chapter focuses on the problem of detecting, characterizing, and determining the concentration of nanomaterials in foods and other biological matrices. After providing an overview of the unique challenges associated with nanoparticle metrology in complex media, sample pretreatment methods (including extraction, digestion, and inline chromatographic separation), imaging analysis, and nanomaterial quantification methods are presented in detail. The chapter also addresses numerous methods under development, including atmospheric scanning electron microscopy, single-particle inductively coupled plasma mass spectrometry, immunological detection methods, and optical techniques such surface plasmon resonance. The chapter concludes with an overview of the research needs in this area.

The release of silver nanoparticles from commercial toothbrushes

The use of silver nanoparticles (NPs) in commercial products has become increasingly common in the past decade, mostly due to their antimicrobial properties. Using Ag NP-containing articles may lead to particle release, which raises concern of human and environmental safety. The published literature addressing particle release is scarce, especially when it comes to quantifying exposure to NPs specifically. In this study, we have experimentally investigated the release of total Ag and Ag NP from commercially available toothbrushes i.e. biodegradable toothbrushes for adults and toothbrushes for children. Toothbrushes were immersed and abraded in tap water for 24h corresponding to more than the whole intended usage time of a toothbrush. The total amount of released Ag was quantified by inductively coupled plasma-mass spectrometry (ICP-MS) analysis, and the Ag NPs were characterized by single particle ICP-MS and transmission electron microscopy (TEM). The median size of the released Ag NPs ranged from 42 to 47nm, and the maximum total Ag release was 10.2ng per toothbrush. The adult toothbrushes were generally releasing more total Ag and NPs than children toothbrushes. In conclusion, our results indicate that the use of Ag NP-impregnated toothbrushes can cause consumer as well as environmental exposure to Ag NPs.

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.

Design of antimicrobial membrane based on polymer colloids/multiwall carbon nanotubes hybrid material with silver nanoparticles

The aim of this study was to obtain membranes with antimicrobial activity presenting a complex sandwich-type structure. The outer layers are comprised of poly(methyl methacrylate) membranes, whereas the inner active layer consists of a modified commercial membrane to achieve antimicrobial properties. This activity arises due to the presence of silver nanoparticles in a material with a hybrid composition deposited on a commercial membrane. This hybrid material consists of polymer colloids and multiwall carbon nanotubes used for both the stabilization of the active layer by the interconnections of the polymer particles and as active component. The filtration tests revealed a good stability of the materials and an increased hydrophilicity of the hybrid membranes. The antimicrobial properties have been evaluated using Staphylococcus aureus and Escherichia coli, and have been correlated with the content and migration rate of silver ions.