Polystyrene nanoplastics alter the ecotoxicological effects of diclofenac on freshwater microalgae Scenedesmus obliquus.

Due to the escalating risk of plastic pollution, nanoplastics have attracted considerable attention in the recent past. They can co-exist and interact with other contaminants like pharmaceuticals in the aquatic environment. Therefore, it is pertinent to understand how these pollutants interact with one another in the ecosystem. The current study examined the individual and combined effects of fluorescent polystyrene nanoplastics (FNPs) and diclofenac (DCF) on Scenedesmus obliquus using a full factorial design. The toxicity of S. obliquus significantly increased in a dose-dependent manner upon exposure to pristine forms of DCF and FNPs. The major cause of individual toxicity of DCF and FNPs in S. obliquus was oxidative stress. In the combined toxicity tests when FNPs (0.01, 0.1, and 1 mg L-1) and DCF (1 mg L-1) were mixed, a synergistic effect was noted compared to the respective pristine FNPs. However, when the DCF concentration in the mixture was decreased to 0.25 mg L-1, the combined toxicity with FNPs (0.01, 0.1, and 1 mg L-1) reduced indicating an antagonistic effect. The independent action model also showed an antagonistic effect for low-dose combinations of DCF and a synergistic effect for high-dose combinations. The estimation of oxidative stress parameters, antioxidant enzyme activity, and photosynthetic pigment content in the algae further validated the cytotoxicity data. The mean hydrodynamic diameter and surface charge analyses further indicated that the colloidal stability of the FNPs in the medium was affected when they were combined with DCF. The key reason for differences in the cytotoxicity of combinations could be observed variations in the aggregation of FNPs and differential adsorption patterns of DCF on the FNPs. These factors efficiently altered cell-particle interactions in the mixture demonstrating a hormesis effect. Thus, this current study highlighted the hazardous nature of the nanoplastics and their co-exposure risks with pharmaceuticals on microalgae in freshwater environments.

Nanoemulsions: The rising star of antiviral therapeutics and nanodelivery system-current status and prospects.

Nanoemulsions (NEs) of essential oil (EO) have significant potential to target microorganisms, especially viruses. They act as a vehicle for delivering antiviral drugs and vaccines. Narrowing of drug discovery pipeline and the emergence of new viral diseases, especially, coronavirus disease, have created a niche to use NEs for augmenting currently available therapeutic options. Published literature demonstrated that EOs have an inherent broad spectrum of activity across bacterial, fungal, and viral pathogens. The emulsification process significantly improved the efficacy of the active ingredients in the EOs. This article highlights the research findings and patent developments in the last 2 years especially, in EO antiviral activity, antiviral drug delivery, vaccine delivery, viral resistance development, and repurposing EO compounds against SARS-CoV-2.

Silver nanorods induced oxidative stress and chromosomal aberrations in the Allium cepa model.

The production of different size and shape silver nanoparticles (AgNPs) has increased considerably in recent years due to several commercial and biological applications. Here, rod-shaped AgNPs (SNRs) were prepared using the microwave-assisted method and characterised by ultraviolet-visible spectroscopy, and transmission electron microscopy analysis. The present study aims to investigate the cyto-genotoxic effect of various concentrations (5, 10, and 15 µM) of SNRs using Allium cepa model. As a result, concentration-dependent cyto-genotoxic effect of SNRs was observed through a decrease in the mitotic index, and an increase in the chromosomal aberrations such as chromosome break, disturbed metaphase, and anaphase bridge. To check the impact of Ag+ ions, 15 µM silver nitrate (AgNO3) was prepared and tested in all the assays. Furthermore, cell viability and different reactive oxygen species assays were performed to test the cytotoxicity evaluation of SNRs. The authors found that in all the tested assays, SNRs at high concentrations (15 µM) and AgNO3 (15 µM) were observed to cause maximal damage to the roots. Therefore, the current study implies that the cytotoxicity and genotoxicity of SNRs were dependent on the concentration of SNRs.

Assessment on interactive prospectives of nanoplastics with plasma proteins and the toxicological impacts of virgin, coronated and environmentally released-nanoplastics.

Recently, the concerns about micro- and nano-plastics (NPs) toxicity have been increasing constantly, however the investigations are quiet meager. The present study provides evidences on the toxicological prospectives of virgin-, coronated- and isolated-NPs on human blood cells and Allium cepa root tip, respectively. Several plasma proteins displayed strong affinity towards NPs and produced multi-layered corona of 13 nm to 600 nm size. The coronated-NPs often attracted each other via non-specific protein-protein attraction which subsequently induced protein-induced coalescence in NPs. In the protein point of view, the interaction caused conformational changes and denaturation of protein thereby turned it as bio-incompatible. The coronated-NPs with increased protein confirmation changes caused higher genotoxic and cytotoxic effect in human blood cells than the virgin-NPs. On the other hand, virgin-NPs and the NPs isolated from facial scrubs hindered the root growth and caused chromosome aberration (ring formation, C-mitotic and chromosomal breaks, etc.) in root of Allium cepa. At the outset, the present study highlights the urgent need of scrutinization and regulation of NPs use in medical applications and pre-requisition of additional studies for assessing the bio-accumulation and bio-magnification of NPs.

Enhanced mosquitocidal efficacy of colloidal dispersion of pyrethroid nanometric emulsion with benignity towards non-target species.

The rising threat of vector-borne diseases and environmental pollution has instigated the investigation of nanotechnology-based applications. The current study deals with a nanotechnological application involving the usage of nanometric pesticides such as permethrin nanoemulsion. The mean droplet diameter and zeta potential of the prepared permethrin nanoemulsion were found to be 12.4 ±â€¯1.13 nm and -20.4 ±â€¯0.56 mV, respectively. The temporal stability of permethrin nanoemulsion was found to be 4 days when checked in the external environment. The permethrin nanoemulsion exhibited LC50 values of 0.038 and 0.047 mgL-1 and 0.049 and 0.063 mgL-1 against larval and pupal stages of Culex tritaeniorhynchus and Aedes aegypti, respectively. The results obtained from the larvicidal and pupicidal assay were corroborated with the histopathological and biochemical profiles of hosts upon treatment with nanometric pesticide. Further, the biosafety studies of the nanopesticide were carried out against different non-target species like freshwater algae (Closterium), Cicer arietinum (Chickpea) and Danio rerio (Zebrafish), and the mosquitocidal concentration of nanopesticide was found to be non-toxic. The following study, therefore, describes the mosquitocidal efficacy of nanometric pesticide formulated in a greener approach, which can become a substitute for conventional pesticide application in an eco-benign manner.

Protective efficacy of microencapsulated seaweed extracts for preventing Aeromonas infections in Oreochromis mossambicus.

Sea weeds are valuable natural assets in aquaculture due to the presence of various bioactive active metabolites in them. Successful fish production and maintenance of disease free culturing systems in aquaculture with environment friendly practices is often affected by various environmental factors. Disease causing pathogens is one of the major factors. These can be controlled by the emerging technologies such as biopolymer based drug delivery systems, feed encapsulations processes and immersions of active ingredients which can possibly facilitate sustainable production by enhancing growth and immune responses in aquaculture animals. The focus of our study is on the identification of antibacterial and antioxidant compounds from two brown seaweeds, Gracilaria foliifera and Sargassum longifolium which have proven bioactive compounds. By a process of microencapsulation these bioactive compounds were encapsulated in the form of beads. Sodium caseinate and xanthan gum were mixed together to form the beads. This process helps to retain and protect the bio active ingredients from adverse reactions such as oxidation and nutritional deterioration. These microencapsulated beads were administered orally to 10 Oreochromis mossambicus the experimental fishes, with average body weight of 10-12 g and challenged against the pathogenic bacteria Aeromonas salmonicida to assess their antibacterial efficacy to control this bacterial pathogen. Microencapsulated bio active compounds were further characterized by FT-Raman, GC-MS, NMR, HPLC and SEM analysis. In this study, the effects of combined formulations of the different bioactive compounds were determined. Data obtained from the treatment of A. salmonicida infection in O. mossambicus using formulated bioactive compounds obtained from these seaweeds showed very high survival percentage in this species of fish.

Effect of microencapsulated probiotic Bacillus vireti 01-polysaccharide extract of Gracilaria folifera with alginate-chitosan on immunity, antioxidant activity and disease resistance of Macrobrachium rosenbergii against Aeromonas hydrophila infection.

Polysaccharide from red seaweed Gracilaria folifera has an interesting functional property of antioxidant activity and prebiotic effect. A feeding trial experiment was directed to examine the effect of probiotic bacteria Bacillus vireti 01 microencapsulated with G. folifera polysaccharide against freshwater prawn M. rosenbergii. Three different feeding trials were conducted for 15 days. The first group contained prawns fed with commercial diet. The second group was comprised of Aeromonas hydrophila challenged prawns fed with commercial feed. The third group consisted of A. hydrophila challenged prawns fed with microencapsulated probiotic-polysaccharide. Survival percentage was significantly decreased in prawns of group2 as compared to that of group1 and group3 prawns (p < 0.0001). The immunological parameters and antioxidant activities (p < 0.001) were found to be increased in group three prawns which were fed with encapsulated probiotic-seaweed polysaccharide and challenged with A. hydrophila as compared to that of group1 and group2. Tissue necrosis, fused lamella, haemocyte infiltration and damage of hepatopancreas lumen and tubule were noted in group2 prawns. There was no histological changes were observed in group3 prawns in which the histological architecture was similar to the control group1. The results suggested that combination of encapsulated probiotic B. vireti 01 and seaweed polysaccharide as dietary feed showed an enhancement of immune response, antioxidant activity and disease resistant of M. rosenbergii against A. hydrophila.

Effect of Dietary Supplementation of Novel Probiotic Bacteria Bacillus vireti 01 on Antioxidant Defence System of Freshwater Prawn Challenged with Pseudomonas aeruginosa.

The aim of the present work was to isolate probiotic bacteria from the intestinal tract of healthy freshwater prawn Macrobrachium rosenbergii and to examine the effect of the isolated probiotic Bacillus vireti 01 in controlling Pseudomonas aeruginosa infection. This is probably the first report on the isolation of probiotic B. vireti 01 from the intestine of M. rosenbergii. The compounds present in B. vireti 01 were identified using GC-MS analysis. The effect of B. vireti 01-incorporated diet on survival and antioxidant enzymes was studied in M. rosenbergii for 2 weeks. Decreased mortality was observed in M. rosenbergii which were administered with the probiotic diet compared to control diet. The antioxidant defence enzymes activities such as SOD, catalase and GSH were analysed in various organs of M. rosenbergii probiotic-treated and control groups. Antioxidant enzyme activities were considerably lowered (p < 0.01) in the muscles, hepatopancreas and gills of prawns infected by P. aeruginosa when compared to that of prawns fed with the probiotic-supplemented diet. The histopathological results suggest that the hepatopancreas, gills and muscles infected with P. aeruginosa were altered structurally. The result of the present work demonstrates that the probiotic B. vireti 01 could be used as a substitute to antibiotics for treating P. aeruginosa infection in prawns.

Biological nanopesticides: a greener approach towards the mosquito vector control.

Mosquitoes, being a vector for some potentially dreadful diseases, pose a considerable threat to people all around the world. The control over the growth and propagation of mosquitoes comprises conventional pesticides, insect growth regulators and other microbial control agents. However, the usage of these common chemicals and conventional pesticides eventually has a negative impact on human health as well as the environment, which therefore becomes a major concern. The lacuna allows nanotechnology to come into action and exploit nanopesticides. Nanopesticides are majorly divided into two categories-synthetic and biological. Several nanoformulations serve as a promising nanopesticide viz. nanoparticles, e.g. biologically synthesised nanoparticles through plant extracts, nanoemulsions prepared using the essential oils like neem oil and citronella oil and nanoemulsion of conventional pesticides like pyrethroids. These green approaches of synthesising nanopesticides make use of non-toxic and biologically derived compounds and hence are eco-friendly with a better target specificity. Even though there are numerous evidences to show the effectiveness of these nanopesticides, very few efforts have been made to study the possible non-target effects on other organisms prevalent in the aquatic ecosystem. This study focuses on the role of these nanopesticides towards the vector control and its eco-safe property against the other non-target species.

Cytogenetic evaluation of gold nanorods using Allium cepa test.

The current study reveals the impact of gold nanorods (NRs) capped with CTAB (cetyltrimethylammonium bromide) or PEG (polyethylene glycol) on Allium cepa. The morphology and surface charge of CTAB- and PEG-capped gold NRs were characterized by electron microscopic and zeta potential analyses. The chromosomal aberrations like clumped chromosome, chromosomal break, chromosomal bridge, diagonal anaphase, disturbed metaphase, laggard chromosome, and sticky chromosome were observed in the root tip cells exposed to different concentrations (0.1, 1, and 10 µg/mL) of CTAB- and PEG-capped gold NRs. We found that both CTAB- and PEG-capped gold NRs were able to induce toxicity in the plant system after 4-h interaction. At a maximum concentration of 10 µg/mL, the mitotic index reduction induced by CTAB-capped gold NRs was 40-fold higher than that induced by PEG-capped gold NRs. The toxicity of gold NRs was further confirmed by lipid peroxidation and oxidative stress analyses. The unbound CTAB also contributed to the toxicity in root tip cells, while PEG alone shows less toxicity to the cells. The vehicle control CTAB contributed to the toxic effects in root tip cells, while PEG alone did not show any toxicity to the cells. The results revealed that even though both the particles have adverse effects on A. cepa, there was a significant difference in the mitotic index and oxidative stress generation in root cells exposed to CTAB-capped gold NRs. Thus, this study concludes that the surface polymerization of gold NRs by PEG can reduce the toxicity of CTAB-capped gold NRs.

Cytogenetic studies of chromium (III) oxide nanoparticles on Allium cepa root tip cells.

The current study evaluates the cytogenetic effects of chromium (III) oxide nanoparticles on the root cells of Allium cepa. The root tip cells of A. cepa were treated with the aqueous dispersions of Cr2O3 nanoparticles (NPs) at five different concentrations (0.01, 0.1, 1, 10, and 100µg/mL) for 4hr. The colloidal stability of the nanoparticle suspensions during the exposure period were ascertained by particle size analyses. After 4hr exposure to Cr2O3 NPs, a significant decrease in mitotic index (MI) from 35.56% (Control) to 35.26% (0.01µg/mL), 34.64% (0.1µg/mL), 32.73% (1µg/mL), 29.6% (10µg/mL) and 20.92% (100µg/mL) was noted. The optical, fluorescence and confocal laser scanning microscopic analyses demonstrated specific chromosomal aberrations such as-chromosome stickiness, chromosome breaks, laggard chromosome, clumped chromosome, multipolar phases, nuclear notch, and nuclear bud at different exposure concentrations. The concentration-dependent internalization/bio-uptake of Cr2O3 NPs may have contributed to the enhanced production of anti oxidant enzyme, superoxide dismutase to counteract the oxidative stress, which in turn resulted in observed chromosomal aberrations and cytogenetic effects. These results suggest that A. cepa root tip assay can be successfully applied for evaluating environmental risk of Cr2O3 NPs over a wide range of concentrations.

Antibacterial activity of neem nanoemulsion and its toxicity assessment on human lymphocytes in vitro.

Neem (Azadirachta indica) is recognized as a medicinal plant well known for its antibacterial, antimalarial, antiviral, and antifungal properties. Neem nanoemulsion (NE) (O/W) is formulated using neem oil, Tween 20, and water by high-energy ultrasonication. The formulated neem NE showed antibacterial activity against the bacterial pathogen Vibrio vulnificus by disrupting the integrity of the bacterial cell membrane. Despite the use of neem NE in various biomedical applications, the toxicity studies on human cells are still lacking. The neem NE showed a decrease in cellular viability in human lymphocytes after 24 hours of exposure. The neem NE at lower concentration (0.7-1 mg/mL) is found to be nontoxic while it is toxic at higher concentrations (1.2-2 mg/mL). The oxidative stress induced by the neem NE is evidenced by the depletion of catalase, SOD, and GSH levels in human lymphocytes. Neem NE showed a significant increase in DNA damage when compared to control in human lymphocytes (P<0.05). The NE is an effective antibacterial agent against the bacterial pathogen V. vulnificus, and it was found to be nontoxic at lower concentrations to human lymphocytes.

Cytotoxicity of aluminum oxide nanoparticles on Allium cepa root tip--effects of oxidative stress generation and biouptake.

The commercial usage of Al2O3 nanoparticles (Al2O3 NPs) has gone up significantly in the recent times, enhancing the risk of environmental contamination with these agents and their consequent adverse effects on living systems. The current study has been designed to evaluate the cytogenetic potential of Al2O3 NPs in Allium cepa (root tip cells) at a range of exposure concentrations (0.01, 0.1, 1, 10, and 100 µg/mL), their uptake/internalization profile, and the oxidative stress generated. We noted a dose-dependent decrease in the mitotic index (42 to 28 %) and an increase in the number of chromosomal aberrations. Various chromosomal aberrations, e.g. sticky, multipolar and laggard chromosomes, chromosomal breaks, and the formation of binucleate cells, were observed by optical, fluorescence, and confocal laser scanning microscopy. FT-IR analysis demonstrated the surface chemical interaction between the nanoparticles and root tip cells. The biouptake of Al2O3 in particulate form led to reactive oxygen species generation, which in turn probably contributed to the induction of chromosomal aberrations.

Trophic transfer potential of aluminium oxide nanoparticles using representative primary producer (Chlorella ellipsoides) and a primary consumer (Ceriodaphnia dubia).

The transfer of nanoparticles through the food chain can lead to bioaccumulation and biomagnification resulting in a long term negative impact on the ecosystem functions. The primary objective of this study was evaluation of aluminium oxide nanoparticles transfer from primary producers to primary consumers. A simple set up consisting of a primary producer (Chlorella ellipsoides) and a primary consumer (Ceriodaphnia dubia) was used. Here, C. ellipsoides were exposed to the varying concentrations of the nanoparticles ranging from 20 to 120µg/mL (196 to 1176µM) for 48h and the infested algal cells were used as the feed to C. dubia. The bioaccumulation of the nanoparticles into the daphnids was noted and the biomagnification factors were computed. The exposure was noted to cause subtle alterations in the feeding behaviour of the daphnids. This might have long term consequences in the energy flow through the food chain. The reproductive behaviour of the daphnids remained unaffected upon exposure to nanoparticle infested algal feed. Distinct observations at ultra-structural scale using transmission electron microscopy provided visual evidences for the disrupted feeding behaviour upon exposure to nanoparticle treated algae. Internalization of nanoparticle like inclusion bodies in the intracellular space of algae was also detected. The findings were further substantiated by a detailed analysis of hydrodynamic stability, bioavailability and dissolution of ions from the nanoparticles over the exposure period. Altogether, the study brings out the first of its kind of observation of trophic transfer potential/behaviour of aluminium oxide nanoparticles and its probable impacts on the energy flow in the fresh water aquatic ecosystem.

In vivo genotoxicity assessment of titanium dioxide nanoparticles by Allium cepa root tip assay at high exposure concentrations.

The industrial production and commercial applications of titanium dioxide nanoparticles have increased considerably in recent times, which has increased the probability of environmental contamination with these agents and their adverse effects on living systems. This study was designed to assess the genotoxicity potential of TiO2 NPs at high exposure concentrations, its bio-uptake, and the oxidative stress it generated, a recognised cause of genotoxicity. Allium cepa root tips were treated with TiO2 NP dispersions at four different concentrations (12.5, 25, 50, 100 µg/mL). A dose dependant decrease in the mitotic index (69 to 21) and an increase in the number of distinctive chromosomal aberrations were observed. Optical, fluorescence and confocal laser scanning microscopy revealed chromosomal aberrations, including chromosomal breaks and sticky, multipolar, and laggard chromosomes, and micronucleus formation. The chromosomal aberrations and DNA damage were also validated by the comet assay. The bio-uptake of TiO2 in particulate form was the key cause of reactive oxygen species generation, which in turn was probably the cause of the DNA aberrations and genotoxicity observed in this study.

Pathogenecity of Pseudomonas aeruginosa in Oreochromis mossambicus and treatment using lime oil nanoemulsion.

Fish diseases caused by Pseudomonas aeruginosa, a known pathogenic organism, is responsible for considerable economic losses in the commercial cultivation of Oreochromis mossambicus (Tilapia). The bacteria were injected into healthy fish through intramuscular injection, oral and immersion challenge. Infection was confirmed by histopathological investigation of the infected organs. Lime nanoemulsion was prepared and the effectiveness of the nanoemulsion was studied both in vitro and in vivo by well diffusion assay and in vivo in the artificially infected fish. Results showed that the lime nanoemulsion was effective against the P. aeruginosa infection in O. mossambicus both in vitro and in vivo.

Eugenol-loaded antimicrobial nanoemulsion preserves fruit juice against, microbial spoilage.

Oil-in-water nanoemulsion was formulated using sesame oil, non-ionic surfactant (Tween20/Tween80) and water by ultrasound cavitation method. Development of nanoemulsion was optimized for process parameters such as surfactant type, surfactant concentration and emulsification time to obtain lower droplet diameter with greater stability. Increase in surfactant concentration and emulsification time resulted in nanoemulsion with minimized droplet diameter. Tween80 was more effective in reducing droplet size when compared to that of Tween20. Selected formulation with optimized process parameter (with oil-surfactant mixing ratio of 1:3 v/v and Tween80 as surfactant) was used for delivery of eugenol. Eugenol-loaded nanoemulsion was formulated with droplet diameter of 13 nm and was stable for more than 1 month. Sesame oil blended eugenol-loaded nanoemulsion demonstrated lower droplet size and higher stability than only-eugenol (without sesame oil) nanoemulsion. Eugenol-loaded nanoemulsion S3E3 exhibited antibacterial activity against Staphylococcus aureus. Inactivation kinetics of S. aureus showed time and concentration killing of bacteria upon treatment with S3E3 nanoemulsion. Fluorescence microscopy results demonstrated that S3E3 nanoemulsion treatment resulted in alteration of membrane permeability. In situ assessment of S3E3 in orange juice exhibited a significant reduction in the native bacteria population.

Ultrasonic emulsification of eucalyptus oil nanoemulsion: antibacterial activity against Staphylococcus aureus and wound healing activity in Wistar rats.

The plant derived essential oil nanoemulsion was prepared using a mixture of components containing eucalyptus oil as organic phase, water as continuous phase, and non ionic surfactant, Tween 80, as emulsifier at a particular proportion of 1:1 v/v%. The ultrasonication was applied for varied processing time from 0 to 30 min to study the effect of time on the formation of nanoemulsion and physical stability of formulation by this method. The transparency and stability of emulsion was enhanced when the sonication time was increased compared to hand blender emulsion. The most stable nanoemulsion was obtained in 30 min sonication having the mean droplet diameter of 3.8 nm. The antibacterial studies of nanoemulsion against Staphylococcus aureus by time kill analysis showed complete loss of viability within 15 min of interaction. Observations from scanning electron microscopy of treated bacterial cells confirmed the membrane damage compared to control bacteria. Furthermore, the wound healing potential and skin irritation activity of the formulated nanoemulsion in Wistar rats, suggested non-irritant and higher wound contraction rate with respect to control and neomycin treated rats. These results proposed that the formulated system could be favourable for topical application in pharmaceutical industries.

Autocatalytic growth of biofunctionalized antibacterial silver nanoparticles.

Development of eco-friendly processes for nanosynthesis is gaining importance owing to the widespread application of nanoparticles (NPs). In the present study, we have explained the mechanism and kinetics of bioreduction in the biosynthesis of silver nanoparticles (AgNPs) using aqueous leaf extract of Rhizophora apiculata. Spectrophotometric methods were employed to quantify the bioactive molecules present before and after the reduction process. The results showed that the polyphenols were the main components responsible for the biosynthesis of AgNPs, which was further confirmed by Fourier transform infrared spectroscopy. The kinetics of formation of AgNPs were monitored by time-resolved spectrophotometric and X-ray diffraction studies, which revealed that the NP formation is an autocatalytic process with a rate constant of 1.9 × 10(-2)  Min(-1) . The NPs were characterized using spectroscopic and microscopic techniques like ultraviolet-visible absorption spectroscopy, dynamic light scattering, transmission electron microscopy, scanning electron microscopy-energy-dispersive X-ray spectroscopy, and X-ray diffraction. The biogenic AgNPs showed substantial inhibitory activity to Proteus mirabilis, Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus with minimum inhibitory concentration values of 2.5, 12.5, 2.5, and 31.25 µg/mL, respectively. The current research provides an insight into the mechanistic aspects of bioreduction and formation of AgNPs.

Ceriodaphnia dubia as a potential bio-indicator for assessing acute aluminum oxide nanoparticle toxicity in fresh water environment.

Growing nanomaterials based consumer applications have raised concerns about their potential release into the aquatic ecosystems and the consequent toxicological impacts. So environmental monitoring of the nanomaterials in aqueous systems becomes imperative. The current study reveals the potential of Ceriodaphnia dubia (C. dubia) as a bio-indicator for aluminum oxide nanoparticles in a fresh water aquatic ecosystem where it occupies an important ecological niche as a primary consumer. This study aims to investigate the aluminium oxide nanoparticle induced acute toxicity on Ceriodaphnia dubia in a freshwater system. The bioavailability of the aluminum oxide nanoparticles has been studied with respect to their aggregation behavior in the system and correlated with the toxicity endpoints. The oxidative stress generated by the particles contributed greatly toward their toxicity. The crucial role of leached aluminium ion mediated toxicity in the later phases (48 h and 72 h) in conjunction with the effects from the nano-sized particles in the initial phases (24 h) puts forth the dynamics of nanotoxicity in the test system. The internalization of nanoparticles (both gross and systemic uptake) as substantiated through the transmission electron microscopy (TEM) and inductively coupled plasma optical emission spectral (ICP-OES) analysis was another major contributor toward acute toxicity. Concluding the present study, Ceriodaphnia dubia can be a promising candidate for bio-monitoring the aluminium oxide nanoparticles in a fresh water system.