Tissue-specific direct microtransfer of nanomaterials into Drosophila embryos as a versatile in vivo test bed for nanomaterial toxicity assessment

Evaluation of Sodium Alginate Stabilized Nanoparticles and Antibiotics against Drug Resistant Escherichia coli Isolated from Gut of Houbara Bustard Bird

Alternative approaches and/or modified approaches to tackle resistance in gut microbes are need of the hour. The current study was planned to find the resistance modulation and toxicity potential of sodium alginate stabilized MgO nanoparticles and antibiotics against Escherichia coli (E. coli) isolated from the gut of Houbara bustard bird ( $n=105$ fecal samples). The preparations consisted of gel stabilized ampicillin (G+A), gel stabilized MgO and ampicillin (G+M+A), gel stabilized MgO and cefoxitin (G+M+C), gel stabilized tylosin (G+T), gel stabilized MgO and tylosin (G+M+T), and gel stabilized MgO (M+G). The fecal samples showed 53% (56/105) prevalence of E. coli which was found to be significantly ( $p<0.05$ ) associated with most of the assumed factors and resistant to multiple drugs. G+M+T showed the lowest ( $4.883\pm 0.00$ μg/mL) minimum inhibitory concentration (MIC) followed G+M+C, G+M+A, G+A, M+G, and G+T. Significant reduction ( $p<0.05$ ) in MIC with respect to incubation interval found at the 16th hr for G+M+A, G+A, and G+M+C that further remained nonsignificant ( $p>0.05$ ) onwards until the 24th hr of incubation. In the case of G+T and M+G, significant reduction in MIC was found at the 20th hr and 24th hr of incubation. Ecotoxicology and histopathology trials on snails showed mild changes in MICs of the preparations. The study thus concluded increasing drug resistance in E. coli of houbara bird while sodium alginate stabilized MgO nanoparticles and antibiotics were effective alternative antibacterial composites with mild toxicity.

Fertility and Iron Bioaccumulation in Drosophila melanogaster Fed with Magnetite Nanoparticles Using a Validated Method

Research on nanomaterial exposure-related health risks is still quite limited; this includes standardizing methods for measuring metals in living organisms. Thus, this study validated an atomic absorption spectrophotometry method to determine fertility and bioaccumulated iron content in Drosophila melanogaster flies after feeding them magnetite nanoparticles (Fe₃O₄NPs) dosed in a culture medium (100, 250, 500, and 1000 mg kg⁻¹). Some NPs were also coated with chitosan to compare iron assimilation. Considering both accuracy and precision, results showed the method was optimal for concentrations greater than 20 mg L⁻¹. Recovery values were considered optimum within the 95–105% range. Regarding fertility, offspring for each coated and non-coated NPs concentration decreased in relation to the control group. Flies exposed to 100 mg L⁻¹ of coated NPs presented the lowest fertility level and highest bioaccumulation factor. Despite an association between iron bioaccumulation and NPs concentration, the 500 mg L⁻¹ dose of coated and non-coated NPs showed similar iron concentrations to those of the control group. Thus, Drosophila flies’ fertility decreased after NPs exposure, while iron bioaccumulation was related to NPs concentration and coating. We determined this method can overcome sample limitations and biological matrix-associated heterogeneity, thus allowing for bioaccumulated iron detection regardless of exposure to coated or non-coated magnetite NPs, meaning this protocol could be applicable with any type of iron NPs.

Particle toxicology and health - where are we?

Background

Particles and fibres affect human health as a function of their properties such as chemical composition, size and shape but also depending on complex interactions in an organism that occur at various levels between particle uptake and target organ responses.

While particulate pollution is one of the leading contributors to the global burden of disease, particles are also increasingly used for medical purposes. Over the past decades we have gained considerable experience in how particle properties and particle-bio interactions are linked to human health. This insight is useful for improved risk management in the case of unwanted health effects but also for developing novel medical therapies. The concepts that help us better understand particles’ and fibres’ risks include the fate of particles in the body; exposure, dosimetry and dose-metrics and the 5 Bs: bioavailability, biopersistence, bioprocessing, biomodification and bioclearance of (nano)particles. This includes the role of the biomolecule corona, immunity and systemic responses, non-specific effects in the lungs and other body parts, particle effects and the developing body, and the link from the natural environment to human health. The importance of these different concepts for the human health risk depends not only on the properties of the particles and fibres, but is also strongly influenced by production, use and disposal scenarios.

Conclusions

Lessons learned from the past can prove helpful for the future of the field, notably for understanding novel particles and fibres and for defining appropriate risk management and governance approaches.

Synthesis of Positively and Negatively Charged CeO2 Nanoparticles: Investigation of the Role of Surface Charge on Growth and Development of Drosophila melanogaster

Monodispersed cerium oxide nanoparticles (CeO₂ NPs) with positive and negative surface potential were synthesized by co-precipitation method using hexamethylenetetramine (HMT) and poly(vinylpyrrolidone) (PVP), respectively, as precipitating agents. Synthesized NPs were characterized with scanning electron microscopy (SEM), UV-Visible (UV-Vis) spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, and powder X-ray diffraction (XRD). Positively charged NPs of about 30 ± 10 nm in size formed within 5 h, aggregated in number, and resulted in larger-sized NPs as a function of time. The CeO₂ NPs were administered to Drosophila as a part of their diet to study the effects on the growth and development of Drosophila. While the positively charged NPs did not affect the growth of the third instar larvae, the negatively charged NPs delayed the growth of larvae by about 7 days. It required 7 more days to reach the stage of adult fly. TEM imaging of the larvae gut showed that positively charged NPs were found to be smaller, whereas the size of negatively charged NPs remained unchanged. This biodegradability could be the reason for the delayed larvae growth in the case of negatively charged particles. The distance covered by such second instar larvae fed with diet containing negatively charged CeO₂ NPs was significantly lower, and their size was significantly smaller when compared to the crawling activity and size of the third instar larvae of the control group. Such positively charged NPs have high potential for use as drug delivery carriers for the treatment of disease, and negatively charged NPs may play a rather detrimental role.

Drosophotoxicology: An Emerging Research Area for Assessing Nanoparticles Interaction with Living Organisms

The rapid development of nanotechnology allowed the fabrication of a wide range of different nanomaterials, raising many questions about their safety and potential risks for the human health and environment. Most of the current nanotoxicology research is not standardized, hampering any comparison or reproducibility of the obtained results. Drosophotoxicology encompasses the plethora of methodological approaches addressing the use of Drosophila melanogaster as a choice organism in toxicology studies. Drosophila melanogaster model offers several important advantages, such as a relatively simple genome structure, short lifespan, low maintenance cost, readiness of experimental manipulation comparative to vertebrate models from both ethical and technical points of view, relevant gene homology with higher organisms, and ease of obtaining mutant phenotypes. The molecular pathways, as well as multiple behavioral and developmental parameters, can be evaluated using this model in lower, medium or high throughput type assays, allowing a systematic classification of the toxicity levels of different nanomaterials. The purpose of this paper is to review the current research on the applications of Drosophila melanogaster model for the in vivo assessment of nanoparticles toxicity and to reveal the huge potential of this model system to provide results that could enable a proper selection of different nanostructures for a certain biomedical application.