Engineering the surface of graphene oxide with bovine serum albumin for improved biocompatibility in Caenorhabditis elegans

Nitrogen-doped carbon dots: a novel biosensing platform for selective norfloxacin detection and bioimaging

Incomplete metabolism and non-biodegradable nature of norfloxacin (NORx) lead to its persistent residues in the environment and food, potentially fostering the emergence of antibiotic resistance and posing a significant threat to public health. Hence, we developed a norfloxacin sensor employing hydrothermally synthesized N-doped carbon dots (N-Ch-CQDs) from chitosan and PEI demonstrated high sensitivity and specificity towards the antibiotic detection. The quantum yield of excitation-dependent emission of N-Ch-CQDs was effectively tuned from 4.6 to 21.5% by varying the concentration of PEI (5-15%). With the enhanced fluorescence in the presence of norfloxacin, N-Ch-CQDs exhibited a linear detection range of 20-1400 nM with a limit of detection (LoD) of 9.3 nM. The high biocompatibility of N-Ch-CQDs was confirmed in the in vitro and in vivo model and showed the environment-friendly nature of the sensor. Detailed study elucidated the formation of strong hydrogen bonds between N-Ch-CQDs and NORx, leading to fluorescence enhancement. The developed sensor's capability to detect NORx was evaluated in water and milk samples. The recovery rate ranged from 98.5% to 103.5%, demonstrating the sensor's practical applicability. Further, the bioimaging potential of N-Ch-CQDs was demonstrated in both the in vitro (L929 cells) and in vivo model (C. elegans). The synergistic influence of the defecation pattern and functioning of intestinal barrier mitigates the translocation of N-Ch-CQDs into the reproductive organ of nematodes. This study revealed the bioimaging and fluorescent sensing ability of N-Ch-CQDs, which holds significant promise for extensive application in the biomedical field.

Aged polystyrene microplastics cause reproductive impairment via DNA-damage induced apoptosis in Caenorhabditis elegans

Although polystyrene microplastics (PS-MPs) could induce toxic effects on environmental organisms, the toxicity of aged PS-MPs with H2O2 on soil organisms remains unclear. Our study utilized Caenorhabditis elegans as model organism to examine the reproductive toxicity of pristine PS-MPs (pPS-MPs) and aged PS-MPs (aPS-MPs) at environmentally relevant concentrations (0.1-100 μg/L). Acute exposure to aPS-MPs could induce greater reproductive impairment compared to pPS-MPs, as evidenced by changes in brood size and egg release. Assessment of gonad development using the number of mitotic cells, length of gonad arm, and relative area of gonad arm as parameters revealed a high reproductive toxicity caused by aPS-MPs exposure. Furthermore, aPS-MPs exposure promoted substantial germline apoptosis. Additionally, exposure to aPS-MPs (100 μg/L) markedly altered the expression of DNA damage-induced apoptosis-related genes (e.g., egl-1, cep-1, clk-2, ced-3, -4, and -9). Alterations in germline apoptosis caused by aPS-MPs were observed in mutants of cep-1, hus-1, egl-1, ced-3, -4, and -9. Consequently, the augmentation of reproductive toxicity resulting from aPS-MPs exposure was attributed to DNA damage-triggered cellular apoptosis. Additionally, the EGL-1-CEP-1-HUS-1-CED-3-CED-4-CED-9 signaling pathway was identified as a key regulator of germline apoptosis in nematodes. Our study provides insights into potential environmental risk of aPS-MPs with H2O2 on environmental organisms.

Polymer chain extenders induce significant toxicity through DAF-16 and SKN-1 pathways in Caenorhabditis elegans: A comparative analysis

Polymer chain extenders, commonly used in plastic production, have garnered increasing attention due to their potential environmental impacts. However, a comprehensive understanding of their ecological risks remains largely unknown. In this study, we employed the model organism Caenorhabditis elegans to investigate toxicological profiles of ten commonly-used chain extenders. Exposure to environmentally relevant concentrations of these chain extenders (ranging from 0.1 µg L-1 to 10 mg L-1) caused significant variations in toxicity. Lethality assays demonstrated the LC50 values ranged from 92.42 µg L-1 to 1553.65 mg L-1, indicating marked differences in acute toxicity. Sublethal exposures could inhibit nematodes' growth, shorten lifespan, and induce locomotor deficits, neuronal damage, and reproductive toxicity. Molecular analyses further elucidated the involvement of the DAF-16 and SKN-1 signaling pathways, as evidenced by upregulated expression of genes including ctl-1,2,3, sod-3, gcs-1, and gst-4. It implicates these pathways in mediating oxidative stress and toxicities induced by chain extenders. Particularly, hexamethylene diisocyanate and diallyl maleate exhibited markedly high toxicity among the chain extenders, as revealed through a comparative analysis of multiple endpoints. These findings demonstrate the potential ecotoxicological risks of polymer chain extenders, and suggest the need for more rigorous environmental safety assessments.

Seawater Accelerated the Aging of Polystyrene and Enhanced Its Toxic Effects on Caenorhabditis elegans

Microplastics (MPs) are emerging pollutants and pose a significant threat to marine ecosystems. Although previous studies have documented the mechanisms and toxic effects of aging MPs in various environments, the impact of the marine environment on MPs remains unclear. In the present study, the aging process of polystyrene (PS) in seawater was simulated and the changes in its physicochemical properties were investigated. Our results showed that the surface of the PS eroded in the seawater, which was accompanied by the release of aged MPs with a smaller size. In situ optical photothermal infrared microspectroscopy revealed that the mechanism of PS aging was related to the opening of the carbonyl group and breaking of the bond between carbon and benzene removal. To verify the toxic effects of aged PS, Caenorhabditis elegans was exposed to PS. Aged PS resulted in a greater reduction in locomotion, vitality, and reproduction than virgin PS. Mechanistically, aged PS led to oxidative stress, high glutathione s-transferase activity, and high total glutathione in worms. Together, our findings provided novel information regarding the accelerated aging of PS in seawater and the increased toxicity of aged PS, which could improve our understanding of MPs' ecotoxicity in the marine environment.

Effect of gamma-ray irradiated reduced graphene oxide (rGO) on environmental health: An in-vitro and in-vivo studies

The unique properties of reduced graphene oxide (rGO) have drawn the attention of scientists worldwide since the last decade and it is explored for a wide range of applications. However, the rapid expansion of rGO use in various products will eventually lead to environenal exposure and rises a safety concern on the environment and humal health risk. Moreover, the utilization of toxic chemicals for the reduction of graphene oxide (GO) into rGO is not environmentally friendly, warranting the exploration of non-toxic approaches. In the present work, rGO was synthesized using a different dose of gamma-ray irradiation and characterized. The in-vitro and in-vivo analysis indicated that the gamma-irradiated rGO induced toxicity depending on its degree of reduction and dosage. In the L929 cells, rGO-30 KGy significantly induced cytotoxicity even at low concentration (1 mg L^-1) by inducing reactive oxygen species (ROS), lactate dehydrogenase (LDH) enzyme production, nuclear fragmentation and apoptosis. The change in morphology of the cells like membrane blebbing and cell rounding was also observed via FESEM. In the in-vivo model Caenorhabditis elegans, rGO-30 KGy significantly affected the functioning of primary and secondary targeted organs and also negatively influenced the nuclear accumulation of transcription factors (DAF-16/FOXO and SKN-1/Nrf2), neuronal health, and antioxidant defense mechanism of the nematodes. The real-time PCR analysis showed significant up-regulation (ced-3, ced-4, cep-1, egl-1, and hus-1) and down-regulation (ced-9) of the gene involved in germ-line and DNA damage-induced apoptosis. The detailed toxicity mechanism of gamma irradiated rGO has been elucidated. This work highlights the toxicity of rGO prepared by gamma-ray radiation and paves way for understating the toxicity mechanism.

Prominent toxicity of isocyanates and maleic anhydrides to Caenorhabditis elegans: Multilevel assay for typical organic additives of biodegradable plastics

Biodegradable plastics (BDP) are increasingly applied; however, there has been of concerns about their environmental safety, especially from nondegradable additive compositions. Until now, data of ecotoxicity of BDP additives is scarce. Here, nematode C. elegans was used to comparatively evaluate toxicity of an isocyanate additive, i.e., Hexamethylene diisocyanate (HDI), a maleic anhydride, i.e., Diallyl maleate (DIM), and other four BDP organic additives. These additives caused lethality of nematodes at µg L^-1 level, of lowest LC₅₀ value of HDI/DIM. Uniform exposure to these additives resulted in various degrees of inhibitions in body volumes and longevity, indicating developmental toxicity. Moreover, BDP additives induced significant elevations of gst-4 expression, especially mean 123.54 %/234.29 % increase in HDI/DIM group, but reduced ges-1 expression, which indicates oxidative damages and mitochondrial dysfunction. BDP additives further caused inhibition in locomotor and food intake/excretion behavior, and related damages of glutamatergic neurons and GABAergic neurons, indicating their neurotoxicity. We found HDI and DIM presented relatively strong effects on susceptible endpoints including lethality, gst-4, mean lifespan, food intake and excretion behavior. Overall, this study suggests prominent ecotoxic risk of isocyanates and maleic anhydrides as BDP additives, which is significant for the selection of environmentally friendly BDP additives.

Green synthesis of zinc oxide nanoparticles using Cananga odorata essential oil and its antibacterial efficacy in vitro and in vivo

Zinc oxide (ZnO) nanostructure exhibits antimicrobial properties, which have prompted more research on their bactericidal effect against foodborne pathogens. The present work focused on the green synthesis of ZnO nanoparticles (ZnO NPs) using Cananga odorata essential oil. The synthesized ZnO NPs were characterized by XRD, UV-Vis spectroscopy, zeta potential, SEM, and FT-IR analysis. The bactericidal activity of biosynthesized ZnO NPs was tested against Pseudomonas aeruginosa and Staphylococcus aureus. The in vitro results indicate that ZnO NPs have excellent antibacterial activity and that the bactericidal and bacteriostatic mechanisms are based on ROS production and depend on its penetration and interaction with bacterial cells. Moreover, ZnO NPs were found to be non-toxic to Caenorhabditis elegans, an in vivo animal model, up to 1 g/L and exert antibacterial activity by reducing the growth and colonization of pathogens. By reducing pathogen virulence, ZnO NPs significantly improved worms' physiological functions such as pharyngeal pumping, body length, reproduction, and movement. The competitive effect of ZnO NPs against pathogenic bacteria increased the gut-barrier integrity of C. elegans. The most interesting observation was noted that ZnO treatment increased the mean survival rate of P. aeruginosa and S. aureus infected C. elegans by 56.6 % and 62.4 %, respectively. As an outcome, our study proved that green synthesized ZnO NPs exhibit remarkable biological properties and can be used as an efficient bactericidal agent against foodborne pathogens.

Cellular and subcellular interactions of graphene-based materials with cancerous and non-cancerous cells

Despite significant advances in early detection and personalized treatment, cancer is still among the leading causes of death globally. One of the possible anticancer approaches that is presently receiving a lot of attention is the development of nanocarriers capable of specific and efficient delivery of anticancer drugs. Graphene-based materials are promising nanocarriers in this respect, due to their high drug loading capacity and biocompatibility. In this review, we present an overview on the interactions of graphene-based materials with normal mammalian cells at the molecular level as well as cellular and subcellular levels, including plasma membrane, cytoskeleton, and membrane-bound organelles such as lysosomes, mitochondria, nucleus, endoplasmic reticulum, and peroxisome. In parallel, we assemble the knowledge about the interactions of graphene-based materials with cancerous cells, that are considered as the potential applications of these materials for cancer therapy including metastasis treatment, targeted drug delivery, and differentiation to non-cancer stem cells. We highlight the influence of key parameters, such as the size and surface chemistry of graphene-based materials that govern the efficiency of internalization and biocompatibility of these particles in vitro and in vivo. Finally, this review aims to correlate the key parameters of graphene-based nanomaterials specially graphene oxide, such as size and surface modifications, to their interactions with the cancerous and non-cancerous cells for designing and engineering them for bio-applications and especially for therapeutic purposes.

Toxicity mitigation and biodistribution of albumin corona coated graphene oxide and carbon nanotubes in Caenorhabditis elegans

In this work, the toxicity and biodistribution of graphene oxide (GO) and oxidized multi-walled carbon nanotubes (MWCNT) were investigated in Caenorhabditis elegans. Bovine serum albumin (BSA) was selected as a model protein to evaluate the influence of protein corona formation on materials physicochemical properties, colloidal stability, and toxicity. Biological assays were performed to assess the effects of bare and albumin corona coated materials on survival, oxidative stress, intestinal barrier permeability, growth, reproduction, and fertility. Critical alterations in topography, surface roughness and chemistry of GO and MWCNT were observed due to albumin corona formation. These modifications were associated with changes in colloidal stability of materials and prevention of their aggregation and sedimentation in nematode testing medium. Both GO and MWCNT caused damage to nematode survival, growth, reproduction, and fertility, as well as enhanced oxidative stress and permeability of the intestinal barrier. But GO was more toxic than MWCNT to C. elegans, especially at long-term assays. Albumin corona mitigated 100% of acute and chronic effects of MWCNT. In contrast, the negative effects of GO were not completely mitigated; GO inhibited 16.2% of nematode growth, 86.5% of reproduction, and 32.0% of fertility at the highest concentration evaluated (10 mg L^-1), while corona coated GO mitigated 50% and 100% of fertility and growth, respectively. Confocal Raman spectroscopy imaging was crucial to point out that bare and albumin corona coated GO and MWCNT crossed the C. elegans intestinal barrier reaching its reproductive organs. However, BSA corona protected the nematodes targeted organs from negative effects from MWCNT and blocked its translocation to other tissues, while coated GO was translocated inside the nematode affecting the functionality of crucial organs. In addition, coated MWCNT was excreted after 2 h of food resumption, whereas coated GO still accumulated in the nematode intestine. Our results demonstrate that the materials different translocation and excretion patterns in C. elegans had a relation to the impaired physiological functions of primary and secondary organs. This work is a contribution towards a better understanding of the impacts of protein corona on the toxicity of graphene oxide and carbon nanotubes; essential information for biological applications and nanosafety.

In Vitro and In Vivo Biocompatibility Studies on Engineered Fabric with Graphene Nanoplatelets

To produce clothes made with engineered fabrics to monitor the physiological parameters of workers, strain sensors were produced by depositing two different types of water-based inks (P1 and P2) suitably mixed with graphene nanoplatelets (GNPs) on a fabric. We evaluated the biocompatibility of fabrics with GNPs (GNP fabric) through in vitro and in vivo assays. We investigated the effects induced on human keratinocytes by the eluates extracted from GNP fabrics by the contact of GNP fabrics with cells and by seeding keratinocytes directly onto the GNP fabrics using a cell viability test and morphological analysis. Moreover, we evaluated in vivo possible adverse effects of the GNPs using the model system Caenorhabditis elegans. Cell viability assay, morphological analysis and Caenorhabditis elegans tests performed on smart fabric treated with P2 (P2GNP fabric) did not show significant differences when compared with their respective control samples. Instead, a reduction in cell viability and changes in the membrane microvilli structure were found in cells incubated with smart fabric treated with P1. The results were helpful in determining the non-toxic properties of the P2GNP fabric. In the future, therefore, graphene-based ink integrated into elastic fabric will be developed for piezoresistive sensors.

One-step preparation of N-doped grapheme quantum dots with high quantum yield for bioimaging and highly sensitive electrochemical detection of isoniazid

Conventional techniques for synthesizing GQDs have a poor quantum yield (QY) that restricts their biological applications. Herein, we present a rapid, cost-effective and high quantum yield synthesis of nitrogen-doped graphene quantum dots (N-GQDs) through a scientific microwave reactor. The reaction parameters like microwave irradiation time, temperature, precursor concentration and pressure were optimized for achieving high quantum yield. The prepared N-GQDs exhibit bright blue fluorescence and excitation independent emission property with a quantum yield of 42.81%. In-vivo investigations on C. elegans revealed that the as-prepared N-GQDs are exceptionally biocompatible and maintain the normal physiological functioning of the primary and secondary targeted organs in nematodes. The synergetic effect of intestinal barrier and defecation behavior mitigates N-GQDs translocation into reproductive organs of nematode. In addition, the N-GQDs modified GCE was tested for electrochemical sensing characteristics towards the anti-tuberculosis drug isoniazid (INZ). The N-GQDs showed appreciable electrocatalytic performance towards INZ with high sensitivity (3.76 μA μM^-1 cm^-1). The differential pulse voltammetry (DPV) analysis of N-GQDs exhibit a lower detection limit of 10.91 nM for INZ. The N-GQDs modified sensor exhibits good reproducibility, excellent anti-interference ability and excellent analytical performance for INZ in real samples like human blood serum and urine samples.

Reproductive toxicity of UV-photodegraded polystyrene microplastics induced by DNA damage-dependent cell apoptosis in Caenorhabditis elegans

Although many studies have investigated the toxic effects of polystyrene microplastics (PS-MPs), toxicity of natural aged of PS-MPs to soil organisms remains unclear. The photodegradation of virgin PS-MPs under UV irradiation was investigated, and reproductive toxicity of pristine and UV-photodegraded PS-MPs at environmental concentrations (0.1-100 μg/L) was examined to Caenorhabditis elegans. Using brood size and egg ejection rate as endpoints, acute exposure to aged PS-MPs resulted in more severe reproductive toxicity than pristine PS-MPs. Exposure to 100 μg/L aged PS-MPs significantly increased the number of HUS-1::GFP foci and the expression of genes required for DNA damage, such as clk-2, cep-1, and egl-1, suggesting induction of DNA damage. Additionally, the number of cell corpses and apoptosis-related gene expression (e.g., ced-3, ced-4, and ced-9) were significantly altered, indicating induction of apoptosis. Germline apoptosis induced by aged PS-MPs was altered in egl-1, hus-1, cep-1, ced-3, ced-4, and ced-9 mutants. Thus, the reproductive toxicity of aged PS-MPs may be due to DNA damage-induced cell apoptosis, and the HUS-1-CEP-1-EGL-1-CED-9-CED-4-CED-3 signalling pathway is involved in regulating cell apoptosis in nematodes.

Rapid one-pot synthesis of PAM-GO-Ag nanocomposite hydrogel by gamma-ray irradiation for remediation of environment pollutants and pathogen inactivation

Designing a cost-effective, high potential and recyclable catalyst remains a challenge. In the present work, a monolithic PAM-GO-Ag hydrogel is prepared by a facile, eco-friendly method using gamma-ray irradiation. The formation of GO-Ag composite by gamma radiation is also investigated and it is authenticated by XRD, FTIR, Raman, XPS and TEM analysis. The PAM-GO-Ag hydrogel exhibits excellent catalytic activity to different catalysant like methylene blue, Rhodamine-B, and pharmaceutical compound ciprofloxacin. The high catalyst carrying capacity and rapid electron shuttling ability of GO plays a significant role in the high performance of PAM-GO-Ag hydrogel. The PAM-GO-Ag hydrogel also exhibits excellent antibacterial activity. The damaged cell membrane, protein leakage, and increased ROS level contribute to the antibacterial activity of PAM-GO-Ag. The monolithic structure of PAM-GO-Ag hydrogel makes it easy to handle, recover, and reuse for several runs without significant loss of catalytic and antibacterial activity. All these results showed the possible application of PAM-GO-Ag hydrogel as a promising catalyst for the reduction of different pollutants and antibacterial agents on a large scale with good reusability.