A systematic review on the effects of nanomaterials on gut microbiota

Nanotechnology in sustainable agriculture: A double-edged sword

Nanotechnology is a rapidly developing discipline that has the potential to transform the way we approach problems in a variety of fields, including agriculture. The use of nanotechnology in sustainable agriculture has gained popularity in recent years. It has various applications in agriculture, such as the development of nanoscale materials and devices to boost agricultural productivity, enhance food quality and safety, improve the efficiency of water and nutrient usage, and reduce environmental pollution. Nanotechnology has proven to be very beneficial in this field, particularly in the development of nanoscale delivery systems for agrochemicals such as pesticides, fertilizers, and growth regulators. These nanoscale delivery technologies offer various benefits over conventional delivery systems, including better penetration and distribution, enhanced efficacy, and lower environmental impact. Encapsulating agrochemicals in nanoscale particles enables direct delivery to the targeted site in the plant, thereby reducing waste and minimizing off-target effects. Plants are fundamental building blocks of all ecosystems and evaluating the interaction between nanoparticles (NPs) and plants is a crucial aspect of risk assessment. This critical review therefore aims to provide an overview of the latest advances regarding the positive and negative effects of nanotechnology in agriculture. It also explores potential future research directions focused on ensuring the safe utilization of NPs in this field, which could lead to sustainable development. © 2024 Society of Chemical Industry.

The gut microbiome meets nanomaterials: exposure and interplay with graphene nanoparticles

Graphene-based nanoparticles are widely applied in many technology and science sectors, raising concerns about potential health risks. Emerging evidence suggests that graphene-based nanomaterials may interact with microorganisms, both pathogens and commensal bacteria, that dwell in the gut. This review aims to demonstrate the current state of knowledge on the interplay between graphene nanomaterials and the gut microbiome. In this study, we briefly overview nanomaterials, their usage and the characteristics of graphene-based nanoparticles. We present and discuss experimental data from in vitro studies, screening tests on small animals and rodent experiments related to exposure and the effects of graphene nanoparticles on gut microbiota. With this in mind, we highlight the reported crosstalk between graphene nanostructures, the gut microbial community and the host immune system in order to shed light on the perspective to bear on the biological interactions. The studies show that graphene-based material exposure is dosage and time-dependent, and different derivatives present various effects on host bacteria cells. Moreover, the route of graphene exposure might influence a shift in the gut microbiota composition, including the alteration of functions and diversity and abundance of specific phyla or genera. However, the mechanism of graphene-based nanomaterials' influence on gut microbiota is poorly understood. Accordingly, this review emphasises the importance of studies needed to establish the most desirable synthesis methods, types of derivatives, properties, and safety aspects mainly related to the routes of exposure and dosages of graphene-based nanomaterials.

Immunotoxicity of engineered nanomaterials and their role in asthma

The toxicity of engineered nanomaterials (ENMs) in vivo and in vitro has formed the basis of most studies. However, the toxicity of ENMs, particularly on the immune system, i.e. immunotoxicity, and their role in manipulating it, are less known. This review addresses the initiation or exacerbation as well as the attenuation of allergic asthma by a variety of ENMs and how they may be used in drug delivery to enhance the treatment of asthma. This review also highlights a few research gaps in the study of the immunotoxicity of ENMs, for example, the potential drawbacks of assays used in immunotoxicity assays; the potential role of hormesis during dosing of ENMs; and the variables that result in discrepancies among different studies, such as the physicochemical properties of ENMs, differences in asthmatic animal models, and different routes of administration.

CsPbBr3 Perovskite Nanoparticles causes Colitis-Like Symptom via Promoting Intestinal Barrier Damage and Gut Microbiota Dysbiosis

Lead-based perovskite nanoparticles (Pb-PNPs) with superior optoelectronic properties are promising alternatives for the next generation of photovoltaics materials. This raises a great concern about their potential exposure toxicity in biological systems. However, little is known about their adverse effects on the gastrointestinal tract system so far. Here, the aim is to investigate the biodistribution, biotransformation, potential gastrointestinal tract toxicity, and effect on the gut microbiota after oral exposure to the CsPbBr3 perovskite nanoparticles (CPB PNPs). The advanced synchrotron radiation based microscopic X-ray fluorescence scanning and X-ray absorption near-edge spectroscopy demonstrate that high doses of CPB (CPB-H) PNPs can gradually transform into different lead-based compounds, subsequently accumulating in the gastrointestinal tract, especially the colon. Meanwhile, the pathological changes of stomach, small intestine, and colon reveal that CPB-H PNPs have higher gastrointestinal tract toxicity than Pb(Ac)2 , consequently leading to colitis-like symptoms. More importantly, 16S rRNA gene sequencing analysis discloses that CPB-H PNPs cause more significant alterations in the richness and diversity of the gut microbiota related to inflammation, intestinal barrier, and immune function than Pb(Ac)2 . The findings may contribute to shedding light on understanding the adverse effects on gastrointestinal tract and gut microbiota of Pb-PNPs.

Graphene oxide exposure alters gut microbial community composition and metabolism in an in vitro human model

Graphene oxide (GO) nanomaterials have unique physicochemical properties that make them highly promising for biomedical, environmental, and agricultural applications. There is growing interest in the use of GO and extensive in vitro and in vivo studies have been conducted to assess its nanotoxicity. Although it is known that GO can alter the composition of the gut microbiota in mice and zebrafish, studies on the potential impacts of GO on the human gut microbiome are largely lacking. This study addresses an important knowledge gap by investigating the impact of GO exposure- at low (25 mg/L) and high (250 mg/L) doses under both fed (nutrient rich) and fasted (nutrient deplete) conditions- on the gut microbial communitys' structure and function, using an in vitro model. This model includes simulated oral, gastric, small intestinal phase digestion of GO followed by incubation in a colon bioreactor. 16S rRNA amplicon sequencing revealed that GO exposure resulted in a restructuring of community composition. 25 mg/L GO induced a marked decrease in the Bacteroidota phylum and increased the ratio of Firmicutes to Bacteroidota (F/B). Untargeted metabolomics on the supernatants indicated that 25 mg/L GO impaired microbial utilization and metabolism of substrates (amino acids, carbohydrate metabolites) and reduced production of beneficial microbial metabolites such as 5-hydroxyindole-3-acetic acid and GABA. Exposure to 250 mg/L GO resulted in community composition and metabolome profiles that were very similar to the controls that lacked both GO and digestive enzymes. Differential abundance analyses revealed that 3 genera from the phylum Bacteroidota (Bacteroides, Dysgonomonas, and Parabacteroides) were more abundant after 250 mg/L GO exposure, irrespective of feed state. Integrative correlation network analysis indicated that the phylum Bacteroidota showed strong positive correlations to multiple microbial metabolites including GABA and 3-indoleacetic acid, are much larger number of correlations compared to other phyla. These results show that GO exposure has a significant impact on gut microbial community composition and metabolism at both low and high GO concentrations.