The effect of titanium dioxide on the biochemical constituents of the brain of Zebrafish (Danio rerio): an FT-IR study

Toxic effects of aniline in liver, gills and kidney of freshwater fish Channa punctatus after acute exposure

Aniline (C6H5NH2) is one of the hazardous aromatic amine where an amino group -NH2) is connected to phenyl ring (C6H5). Based on the evaluation of the 96-hour LC50 of aniline, two sublethal concentrations (4.19 mg/l and 8.39 mg/l) were selected for acute exposure tests in freshwater fish Channa punctatus. The liver, gills and kidney of fish being the principal sites of xenobiotic material accumulation, respiration, biotransformation, and excretion are the focus of the present study. Throughout the exposure time, the comet assay revealed increased tail length and tail DNA percentage indicating maximum damage to liver, gills and kidney of treated group after 96 h. After acute exposure, there was a significant (p ≤ 0.05) increase in the enzymatic activity of glutathione-S-transferase (GST) and acetylcholinesterase (AChE), whereas decline in superoxide dismutase (SOD) and catalase (CAT) activity was observed. Meanwhile, levels of malondialdehyde (MDA) increased over the exposure period for both concentrations. After 96 h of exposure, degree of tissue change (DTC) was evaluated in liver, gill and kidney of aniline exposed fish. Additionally, light microscopy revealed multiple abnormalities in liver, gills and kidney of all the treated groups. Significant changes were observed in the levels of biochemical markers viz., glucose, triglyceride, cholesterol, aspartate transaminase, alanine transaminase and urea following a 96-hour exposure to aniline. Studies using ATR-FTIR and transmission electron microscopy (TEM) revealed changes in biomolecules and structural abnormalities in several tissues of the aniline-exposed groups in comparison to the control group respectively.

An ecofriendly approach to bioremediate nickel oxide nanoparticles using a macrofungus, Pleurotus fossulatus

Nowadays, nickel oxide nanoparticles are in great demands owing to their use in many sectors. These nanoparticles may release into aquatic environment from different industries and cause negative effect on aquatic flora and fauna. Therefore, an effective and efficient method is required to remove these nanoparticles from contaminated water. Hence, the aim of this study was to bioremediate nickel oxide nanoparticles using a macrofungus, Pleurotus fossulatus, and to analyze its impact on fungal physiology. For this purpose, fungal spawns were inoculated in malt dextrose agar media containing different concentrations of nickel oxide nanoparticles (24 mg/l, 48 mg/l, and 100 mg/l) as well as control group (having no nickel oxide nanoparticles) and allowed to grow for a period of 20 days. Fungal mycelia as well as media were collected at different time intervals (5th day, 10th day, 15th day, and 20th day) for evaluation of Ni concentration and different biochemical parameters. Ni removal efficiency of P. fossulatus from media was found to be highest in 48 mg/l (66.98%) followed by 24 mg/l (60.83%) and 100 mg/l (18.03%), respectively. Increased level of metallothionein, lipid peroxidation, activity of different antioxidant enzymes (superoxide dismutase, catalase, glutathione s transferase, glutathione reductase), activity of ligninolytic enzymes (laccase, lignin peroxidase, manganese peroxidase), and shift in FTIR spectra were also reported in mycelia cultured in malt dextrose agar media containing nickel oxide nanoparticles. This study suggests that P. fossulatus has great efficiency to remediate nanoparticles from contaminated water and it can be utilized as potential agent in wastewater treatment plants by different industries.

Neurotoxicity of Titanium Dioxide Nanoparticles: A Comprehensive Review

The increasing use of titanium dioxide nanoparticles (TiO2 NPs) across various fields has led to a growing concern regarding their environmental contamination and inevitable human exposure. Consequently, significant research efforts have been directed toward understanding the effects of TiO2 NPs on both humans and the environment. Notably, TiO2 NPs exposure has been associated with multiple impairments of the nervous system. This review aims to provide an overview of the documented neurotoxic effects of TiO2 NPs in different species and in vitro models. Following exposure, TiO2 NPs can reach the brain, although the specific mechanism and quantity of particles that cross the blood-brain barrier (BBB) remain unclear. Exposure to TiO2 NPs has been shown to induce oxidative stress, promote neuroinflammation, disrupt brain biochemistry, and ultimately impair neuronal function and structure. Subsequent neuronal damage may contribute to various behavioral disorders and play a significant role in the onset and progression of neurodevelopmental or neurodegenerative diseases. Moreover, the neurotoxic potential of TiO2 NPs can be influenced by various factors, including exposure characteristics and the physicochemical properties of the TiO2 NPs. However, a systematic comparison of the neurotoxic effects of TiO2 NPs with different characteristics under various exposure conditions is still lacking. Additionally, our understanding of the underlying neurotoxic mechanisms exerted by TiO2 NPs remains incomplete and fragmented. Given these knowledge gaps, it is imperative to further investigate the neurotoxic hazards and risks associated with exposure to TiO2 NPs.

Assessment of hazardous impact of nickel oxide nanoparticles on biochemical and histological parameters of gills and liver tissues of Heteropneustes fossilis

BACKGROUND

The aim of the present study was to assess the hazardous impact of nickel oxide nanoparticles (NiO NPs) on gills and liver of Heteropneustes fossilis.

METHODS

Fishes were treated with four concentrations of NiO NPs for a period of 14 days. Nickel accumulation, lipid peroxidation, antioxidant enzymes activities (superoxide dismutase, catalase, glutathione s transferase & glutathione reductase), liver enzymes activities (aspartate amino transferase, alanine transaminase, & alkaline phosphatase), Na⁺/K⁺ ATPase activity, FTIR, metallothionein content, ethoxyresorufin-o-deethylase activity, immunohistochemistry, histology and scanning electron microscopy were analyzed in both gills and liver tissues.

RESULTS

Results revealed increased accumulation of nickel in both the tissues of exposed fishes. Lipid peroxidation and activities of different antioxidant enzymes increased (except superoxide dismutase) in both the tissues after exposure. Fluctuations in liver enzymes activities and variation in the activity of Na⁺/K⁺ ATPase were also observed. FTIR data revealed shift in peaks position in both the tissues. Level of metallothionein and its expression as well as activity of ethoxyresorufin-o-deethylase and expression of CYP1A also increased in both the target tissues of treated fishes. Furthermore, histological investigation and scanning electron microscopy showed structural damages in gills as well as liver tissues of exposed fishes.

CONCLUSION

Our results suggest that NiO NPs cause deteriorating effects on the gill and liver tissues of fish, therefore effluents containing these nanoparticles should be treated before their release into water bodies.

Embryonic Arsenic Exposure Triggers Long-Term Behavioral Impairment with Metabolite Alterations in Zebrafish

Arsenic trioxide (As2O3) is a ubiquitous heavy metal in the environment. Exposure to this toxin at low concentrations is unremarkable in developing organisms. Nevertheless, understanding the underlying mechanism of its long-term adverse effects remains a challenge. In this study, embryos were initially exposed to As2O3 from gastrulation to hatching under semi-static conditions. Results showed dose-dependent increased mortality, with exposure to 30-40 µM As2O3 significantly reducing tail-coiling and heart rate at early larval stages. Surviving larvae after 30 µM As2O3 exposure showed deficits in motor behavior without impairment of anxiety-like responses at 6 dpf and a slight impairment in color preference behavior at 11 dpf, which was later evident in adulthood. As2O3 also altered locomotor function, with a loss of directional and color preference in adult zebrafish, which correlated with changes in transcriptional regulation of adsl, shank3a, and tsc1b genes. During these processes, As2O3 mainly induced metabolic changes in lipids, particularly arachidonic acid, docosahexaenoic acid, prostaglandin, and sphinganine-1-phosphate in the post-hatching period of zebrafish. Overall, this study provides new insight into the potential mechanism of arsenic toxicity leading to long-term learning impairment in zebrafish and may benefit future risk assessments of other environmental toxins of concern.

Biomolecular alterations in the early life stages of four food fish following acute exposure of Triclosan

We investigated the effect of acute concentrations of triclosan (TCS; 96 h exposure and 10d post exposure) on the free amino acid, primary (SDS-PAGE) and secondary (FT-IR) structure of proteins in the embryos/larvae of Cyprinus carpio, Ctenopharyngodon idella, Labeo rohita and Cirrhinus mrigala. A concentration dependent increase in free amino acids, upregulation of polypeptides (100 and 70 kDa in C. carpio, C. idella and L. rohita, 55, 45, 36 kda in C. idella and L. rohita and 22 kDa in all the fish) and a decline in percent area of all the selected peaks of the FT-IR spectra was observed after exposure and recovery period. The decline in percent area was greatest for L. rohita at peak 1080 - 1088 cm^-1 (-75.99%) after exposure and at peak 2854 - 2855 cm^-1 (-53.59%) after recovery. Curve fitting analysis revealed a decrease in α-helices and increase in β-sheets in all fish after exposure and recovery period. The results suggest that TCS elicits alterations in biomolecules of fish embryos.

Viable but Nonculturable State of Yeast Candida sp. Strain LN1 Induced by High Phenol Concentrations

Microbial degradation plays an important role in environmental remediation. However, most microorganisms' pollutant-degrading capabilities are weakened due to their entry into a viable but nonculturable (VBNC) state. Although there is some evidence for the VBNC state of pollutant-degrading bacteria, limited studies have been conducted to investigate the VBNC state of pollutant degraders among fungi. In this work, the morphological, physiological, and molecular changes of phenol-degrading yeast strain LN1 exposed to high phenol concentrations were investigated. The results confirmed that Candida sp. strain LN1, which possessed a highly efficient capability of degrading 1,000 mg/liter of phenol as well as a high potential for aromatic compound degradation, entered into the VBNC state after 14 h of incubation with 6,000 mg/liter phenol. Resuscitation of VBNC cells can restore their phenol degradation performance. Compared to normal cells, significant dwarfing, surface damage, and physiological changes of VBNC cells were observed. Molecular analysis indicated that downregulated genes were related to the oxidative stress response, xenobiotic degradation, and carbohydrate and energy metabolism, whereas upregulated genes were related to RNA polymerase, amino acid metabolism, and DNA replication and repair. This report revealed that a pollutant-degrading yeast strain entered into the VBNC state under high concentrations of contaminants, providing new insights into its survival status and bioremediation potential under stress. IMPORTANCE The viable but nonculturable (VBNC) state is known to affect the culturability and activity of microorganisms. However, limited studies have been conducted to investigate the VBNC state of other pollutant degraders, such as fungi. In this study, the VBNC state of a phenol-degrading yeast strain was discovered. In addition, comprehensive analyses of the morphological, physiological, and molecular changes of VBNC cells were performed. This study provides new insight into the VBNC state of pollutant degraders and how they restored the activities that were inhibited under stressful conditions. Enhanced bioremediation performance of indigenous microorganisms could be expected by preventing and controlling the formation of the VBNC state.

Genetic and biochemical changes in liver and kidney of Channa punctatus after treatment with 2-naphthalene sulfonate

2-Naphthalene sulfonate (2NS) is a sulfonated aromatic compound and a momentous intermediate involved in the synthesis of dyes and surfactants. Thus, the present experiment was undertaken to evaluate the variation in biochemical constituents in liver and kidney of fresh water fish, Channa punctatus, after 2NS intoxication. After determination of lethal dose (LD) two sublethal doses, i.e. 0.33 mg/15 g body weight (one-half of LD₅₀) and 0.16 mg/15 g b.w. (one-fourth of LD₅₀) were selected for analyzing oxidative stress, genotoxicity and bioaccumulative potential of 2NS. Highest significant increase in oxidative stress and DNA damage in the exposed groups as compared with control group (P ≤ 0.05) was observed at 96 h. However, decreased values of all the studied parameters after 30 days indicate repair capacity of fish. In order to study the alterations observed in biomolecules including lipids, proteins and nucleic acids, histopathology along with spectroscopic analysis using attenuated total reflection-Fourier transform infrared was also performed for 96 h exposed group. In addition, protein secondary structure analysis was focused in this study, which reveals alterations in α-helix and β-sheet structure after 2NS intoxication. Furthermore, the bioaccumulative potential of 2NS was revealed using high-performance liquid chromatography showing 1.83 and 45.54 μg/ml concentration of 2NS in liver and kidney homogenate, respectively. As the study revealed 2NS as the potential health hazard to aquatic organisms, it entails the augmentation and adoption of pertinent policies regarding the management of such toxic compounds.

Titanium dioxide nanoparticle affects motor behavior, neurodevelopment and axonal growth in zebrafish (Danio rerio) larvae

More attention has been recently paid to the ecotoxicity of titanium dioxide nanoparticles (nano-TiO₂) owing to its common use in many fields. Although previous studies have shown that nano-TiO₂ is neurotoxic, the mechanism is still largely unknown. In the present study, zebrafish embryos were exposed to 0.01, 0.1, and 1.0 mg/L nano-TiO₂ and 1.0 mg/L micro-TiO₂ for up to 6 days post-fertilization (dpf). Exposure to 1.0 mg/L nano-TiO₂ significantly decreased the body length and weight of zebrafish larvae; however, the hatching and mortality rate of zebrafish embryos did not change. Behavioral tests showed that nano-TiO₂ exposure significantly reduced the swimming speed and clockwise rotation times of the larvae. The results revealed that nano-TiO₂ treatment adversely affected motor neuron axon length in Tg (hb9-GFP) zebrafish and decreased central nervous system (CNS) neurogenesis in Tg (HuC-GFP) zebrafish. Additionally, real-time polymerase chain reaction analysis demonstrated that genes associated with neurogenesis (nrd and elavl3) and axonal growth (α1-tubulin, mbp, and gap43) were significantly affected by nano-TiO₂ exposure. In conclusion, our study demonstrated that early-life stage exposure of zebrafish to nano-TiO₂ causes adverse neural outcomes through the inhibition of neurodevelopment and motor neuron axonal growth.

FTIR study of the binary effect of titanium dioxide nanoparticles (nTiO2) and copper (Cu2+) on the biochemical constituents of liver tissues of catfish (Clarias gariepinus)

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The mixture of nanomaterial and essential metal is of concern for freshwater.

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Co-exposure of titanium dioxide nanoparticles (nTiO₂) and copper (Cu²⁺) revealed.

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Notable alteration of biochemical constituents and histopathology of liver tissues.

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FTIR and histological techniques are adequate for the monitoring of changes in fish tissues.

The increasing demand for nanomaterials and essential metals leads to their discharge into the aquatic ecosystems through water run-off and this is of great concern for the aquatic biodiversity.

In the present study titanium dioxide nanoparticles (nTiO₂) and copper (Cu²⁺) effects in binary mixture on the biochemical constituents of the liver of Clarias gariepinus by using Fourrier- transform infrared (FT-IR) techniques was examined. The FT-IR revealed significant differences in absorbance intensities between the control and exposed liver tissues demonstrating changes on the critical biochemical constituents such as proteins, lipids and carbohydrates. This result further reveals the binary mixture responsible for the absence of CH₃ bending lipids in liver tissues due to their toxic effect. The observed synergistic decreasing ratio of integrated area (1545/3296) for binary mixture exposed liver tissues suggests that lipid degradation predominates over amide formation. In addition, binary mixture causes an alteration in protein secondary structures by decreasing the β turns of liver tissues. Histology in liver showed marked damages. The frequent alteration in the biochemical constituents in the liver tissues of C. gariepinus could be an indication of alteration of existing biochemical components or the expression of new components.

Role of quercetin and caloric restriction on the biomolecular composition of aged rat cerebral cortex: An FTIR study

Aging brain is characterized by a change in biomolecular composition leading to a diverse range of neurological diseases. Anti-aging research is of current interest, to lessen the burden of age-related macromolecular damage through antioxidant supplementation and caloric restriction. However, data concerning the effect of these anti-aging regimens on age-related biomolecular changes in rat brain is still lacking. In the present study, for the first time, we employed Fourier transform infrared (FTIR) spectroscopy, to investigate the effect of quercetin, caloric restriction (CR) and combination of both on alterations in the composition of lipids and proteins of aged rat brain cerebral cortex. Aged male Wistar rats (21 months old) were divided into four groups: Control (CONT), fed pellet diet; Quercetin (QUER), fed quercetin (50 mg/kg/day); CR (caloric restriction) (fed 40% reduced CONT), and CRQ (40% CR and 50 mg/kg/day QUER). Three-month-old rats served as young control (YOUNG). Our short-term study (45 days) shows decreased band area of unsaturated lipids, decreased area ratios of olefinic/lipid and CH₂ antisymmetric stretching (2925 cm^-1)/lipids in CONT group compared to young rats, suggesting age-associated lipid peroxidation in aged rats. A slight decrease in the frequency of CH₂ antisymmetric mode of lipids (whereas no change in CH₂ symmetric mode), but a decrease in bandwidths of both CH₂ antisymmetric and symmetric modes of lipids was observed for CONT group compared to YOUNG. Further, a significant decrease in the peak area of infrared bands of proteins and an increase in the peak area of the CO band of lipids was observed in the CONT group. Our data also show that lower levels of α-helical structures and higher levels of random coils, representing altered protein secondary structure composition in the CONT group compared to YOUNG group. Reduction in neuronal cell density and shrinked nucleus was also observed in aged rats. Increase in the accumulation of oxidative mediated damage to macromolecules and diminished antioxidant levels, could be the possible reason for the age-related alterations in the composition of lipids and proteins. However, the combination of quercetin and CR, but not either treatment alone, significantly prevented the age associated alterations in the lipid and protein profiles in the rat cerebral cortex. Further, our results help to understand the mechanism of action of antioxidants under non-restriction and CR conditions, this might help in the development of novel anti-aging treatments to ameliorate oxidative stress in age-related disorders.

Zebrafish as a Model to Evaluate Nanoparticle Toxicity

Nanoparticles are increasingly being developed for in vivo use, from targeted drug delivery to diagnostics, where they have enormous potential, while they are also being used for a variety of applications that can result in environmental exposure for humans. Understanding how specific nanoparticles interact with cells and cell systems is essential to gauge their safety with respect to either clinical or environmental exposure. Zebrafish is being increasingly employed as a model to evaluate nanoparticle biocompatibility. This review describes this model and how it can be used to assess nanoparticle toxicity at multiple levels, including mortality, teratogenicity, immunotoxicity, genotoxicity, as well as alterations in reproduction, behavior and a range of other physiological readouts. This review also provides an overview of studies using this model to assess the toxicity of metal, metal oxide and carbon-based nanoparticles. It is anticipated that this information will inform research aimed at developing biocompatible nanoparticles for a range of uses.

Zebrafish: A Premier Vertebrate Model for Biomedical Research in Indian Scenario

The zebrafish (Danio rerio) is a versatile model organism that has been used in biomedical research for several decades to study a wide range of biological phenomena. There are many technical advantages of using zebrafish over other vertebrate models. They are readily available, hardy, easy, and inexpensive to maintain in the laboratory, have a short life cycle, and have excellent fecundity. Due to its optical clarity and reproducible capabilities, it has become one of the predominant models of human genetic diseases. Zebrafish research has made rapid strides in the United States and Europe, but in India the field is at an early stage and many researchers still remain unaware of the full research potential of this tiny fish. The zebrafish model system was introduced into India in the early 2000s. Up to now, more than 200 scientific referred articles have been published by Indian researchers. This review gives an overview of the current state of knowledge for zebrafish research in India, with the aim of promoting wider utilization of zebrafish for high level biological studies.

Effects of titanium dioxide nanoparticles exposure on parkinsonism in zebrafish larvae and PC12

Nanomaterials hold significant potential for industrial and biomedical application these years. Therefore, the relationship between nanoparticles and neurodegenerative disease is of enormous interest. In this contribution, zebrafish embryos and PC12 cell lines were selected for studying neurotoxicity of titanium dioxide nanoparticles (TiO₂ NPs). After exposure of different concentrations of TiO₂ NPs to embryos from fertilization to 96 hpf, the hatching time of zebrafish was decreased, accompanied by an increase in malformation rate. However, no significant increases in mortality relative to control were observed. These results indicated that TiO₂ NPs exposure hold a risk for premature of zebrafish embryos, but not fatal. The further investigation confirmed that TiO₂ NPs could accumulate in the brain of zebrafish larvae, resulting in reactive oxygen species (ROS) generation and cell death of hypothalamus. Meanwhile, q-PCR analysis showed that TiO₂ NPs exposure increased the pink1, parkin, α-syn and uchl1 gene expression, which are related with the formation of Lewy bodies. We also observed loss of dopaminergic neurons in zebrafish and in vitro. These remarkable hallmarks are all linked to these Parkinson's disease (PD) symptoms. Our results indicate that TiO₂NPs exposure induces neurotoxicity in vivo and in vitro, which poses a significant risk factor for the development of PD.

Repeated exposure to iron oxide nanoparticles causes testicular toxicity in mice

The aim of this study was to determine whether repeated exposure to iron oxide nanoparticles (Fe₂ O₃ -NPs) could be toxic to mice testis. Fe₂ O₃ -NPs (25 and 50 mg/kg) were intraperitoneally administered into mice once a week for 4 weeks. Our study showed that Fe₂ O₃ -NPs have the ability to cross the blood-testis barrier to get into the testis. The findings showed that exposure resulted in the accumulation of Fe₂ O₃ -NPs which was evidenced from the iron content and accumulation in the testis. Furthermore, 25 and 50 mg/kg Fe₂ O₃ -NPs administration increased the reactive oxygen species, lipid peroxidation, protein carbonyl content, glutathione peroxidase activity, and nitric oxide levels with a concomitant decrease in the levels of antioxidants-superoxide dismutase, catalase, glutathione, and vitamin C. Increased expression of Bax, cleaved-caspase-3, and cleaved-PARP confirms apoptosis. Serum testosterone levels increased with increased concentration of Fe₂ O₃ -NPs exposure. In addition, the histopathological lesions like vacuolization, detachment, and sloughing of germ cells were also observed in response to Fe₂ O₃ -NPs treatment. The data from our study entailed that testicular toxicity caused by Fe₂ O₃ -NPs exposure may be associated with Fe₂ O₃ -NPs accumulation leading to oxidative stress and apoptosis. Therefore, precautions should be taken in the safe use of Fe₂ O₃ -NPs to avoid complications in the fertility of males. Further research will unravel the possible molecular mechanisms on testicular toxicity of Fe₂ O₃ -NPs. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 594-608, 2017.

Insight into visible light-driven photocatalytic degradation of diesel oil by doped TiO2-PS floating composites

TiO2-pearlstone (PS) floatable photocatalysts were synthesized using a facile sol-gel method and confirmed by XRD, N2 adsorption-desorption, SEM, EDX, TEM, FT-IR, XPS, and UV-vis DRS measurements. It has been found that the photocatalysts composed of anatase TiO2 deposited on the surface of PS and formed mesoporous structure. By N or B/N doping, the band gap of the photocatalyst has been narrowed. The obtained floatable photocatalysts can be applied to solar light-driven remediation of oil-contaminated water. Diesel oil was chosen as the model pollutant to evaluate the photocatalytic activity. The results showed B/N-TiO2-PS exhibited the highest photocatalytic activity for diesel oil under visible light irradiation, which is 48 % removal rate for 9 h. The reaction rate constant k of B/N-TiO2-PS is 0.08423 h(-1), which is four times larger than that of pure TiO2-PS. Moreover, the characteristic of floatable makes the photocatalysts easier to separate and reuse, which showed great potential for practical applications in the field of environmental cleanup and solar energy conversion.

Zebrafish: A complete animal model to enumerate the nanoparticle toxicity

Presently, nanotechnology is a multi-trillion dollar business sector that covers a wide range of industries, such as medicine, electronics and chemistry. In the current era, the commercial transition of nanotechnology from research level to industrial level is stimulating the world’s total economic growth. However, commercialization of nanoparticles might offer possible risks once they are liberated in the environment. In recent years, the use of zebrafish (Danio rerio) as an established animal model system for nanoparticle toxicity assay is growing exponentially. In the current in-depth review, we discuss the recent research approaches employing adult zebrafish and their embryos for nanoparticle toxicity assessment. Different types of parameters are being discussed here which are used to evaluate nanoparticle toxicity such as hatching achievement rate, developmental malformation of organs, damage in gill and skin, abnormal behavior (movement impairment), immunotoxicity, genotoxicity or gene expression, neurotoxicity, endocrine system disruption, reproduction toxicity and finally mortality. Furthermore, we have also highlighted the toxic effect of different nanoparticles such as silver nanoparticle, gold nanoparticle, and metal oxide nanoparticles (TiO₂, Al2O₃, CuO, NiO and ZnO). At the end, future directions of zebrafish model and relevant assays to study nanoparticle toxicity have also been argued.

ATR-FTIR spectroscopy reveals polycyclic aromatic hydrocarbon contamination despite relatively pristine site characteristics: Results of a field study in the Niger Delta

Fourier-transform infrared (FTIR) spectroscopy is an emerging technique to detect biochemical alterations in biological tissues, particularly changes due to sub-lethal exposures to environmental contaminants. We have previously shown the potential of attenuated total reflection FTIR (ATR-FTIR) spectroscopy to detect real-time exposure to contaminants in sentinel organisms as well as the potential to relate spectral alterations to the presence of specific environmental agents. In this study based in the Niger Delta (Nigeria), changes occurring in fish tissues as a result of polycyclic aromatic hydrocarbon (PAH) exposure at contaminated sites are compared to the infrared (IR) spectra of the tissues obtained from a relatively pristine site. Multivariate analysis revealed that PAH contamination could be occurring at the pristine site, based on the IR spectra and significant (P<0.0001) differences between sites. The study provides evidence of the IR spectroscopy techniques' sensitivity and supports their potential application in environmental biomonitoring.

Mechanism of TiO2 nanoparticle-induced neurotoxicity in zebrafish (Danio rerio)

Zebrafish (Danio rerio) has been used historically for evaluating the toxicity of environmental and aqueous toxicants, and there is an emerging literature reporting toxic effects of manufactured nanoparticles (NPs) in zebrafish embryos. Few researches, however, are focused on the neurotoxicity on adult zebrafish after subchronic exposure to TiO2 NPs. This study was designed to evaluate the morphological changes, alterations of neurochemical contents, and expressions of memory behavior-related genes in zebrafish brains caused by exposures to 5, 10, 20, and 40 μg/L TiO2 NPs for 45 consecutive days. Our data indicated that spatial recognition memory and levels of norepinephrine, dopamine, and 5-hydroxytryptamine were significantly decreased and NO levels were markedly elevated, and over proliferation of glial cells, neuron apoptosis, and TiO2 NP aggregation were observed after low dose exposures of TiO2 NPs. Furthermore, the low dose exposures of TiO2 NPs significantly activated expressions of C-fos, C-jun, and BDNF genes, and suppressed expressions of p38, NGF, CREB, NR1, NR2ab, and GluR2 genes. These findings imply that low dose exposures of TiO2 NPs may result in the brain damages in zebrafish, provide a developmental basis for evaluating the neurotoxicity of subchronic exposure, and raise the caution of aquatic application of TiO2 NPs.

Influence of Alpha and Gamma-Iron Oxide Nanoparticles on Marine Microalgae Species

The effects of alpha-iron oxide (α-Fe2O3) and gamma-iron oxide (γ-Fe2O3) nanoparticles (NPs) on marine microalgae species (Nannochloropsis sp. and Isochrysis sp.) were investigated in this study. Both Fe2O3 NPs covered the surface of algae with the agglomerates of the nanoparticles. This form of physical NP toxicity significantly decreased the sizes of phytoplankton. Both NPs were toxic to the tested algal species, while α-Fe2O3 showed less toxicity than γ-Fe2O3 NPs for both algal species. A comparative analysis of growth data of the two algal species treated with α-Fe2O3 or γ-Fe2O3 NPs revealed that Isochrysis sp. are more sensitive than Nannochloropsis sp. Toxicity of these widely used NPs to primary producers forming the base of the food chain in aquatic environments might result in widespread adverse effects on aquatic environmental health.

Fourier transform infrared (FT-IR) study on cyanide induced biochemical and structural changes in rat sperm

In the recent years, great attention had been focused on cyanide toxicity because of its widespread use in industries and considered to be a ubiquitous pollutant in the environment. Therefore, the current study aimed to evaluate the toxic effect of cyanide on rat sperms at molecular level by using FT-IR technique. For this purpose, rats were randomly divided into four groups and treated with 0.0, 0.64, 1.2 and 3.2 mg kg^-1 body weight (BW) for the period of 90 days. The group treated with lower dose (0.64 mg kg^-1 BW) showed an insignificant change in all the peaks, except the peaks assigned to olefinic 000000000000 000000000000 000000000000 111111111111 000000000000 111111111111 000000000000 000000000000 000000000000 C-H, CH₂ asymmetric and CH₂ symmetric stretching vibration in the lipids. While, the groups treated with higher doses (1.2 and 3.2 mg kg^-1 BW) showed the significant decrease in the area under the peaks corresponds to different bio-molecules. In addition, spectral second derivative analysis showed the significant alteration in α-helix, turns, β-sheet, aggregated β-sheet and random coil structures in the proteins. In conclusion, the selected higher dosage of cyanide had caused significant decrease in the biochemical composition of rat sperms along with structural changes in the proteins. The FT-IR technique is an excellent tool used for the analysis of oxidative damage in the sperms.

Linking biochemical perturbations in tissues of the African catfish to the presence of polycyclic aromatic hydrocarbons in Ovia River, Niger Delta region

Petroleum hydrocarbons including polycyclic aromatic hydrocarbons (PAHs) are a pollution issue in the Niger Delta region due to oil industry activities. PAHs were measured in the water column of the Ovia River with concentrations ranging from 0.1 to 1055.6 ng L(-1). Attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy detected alterations in tissues of the African catfish (Heterobranchus bidorsalis) from the region showed varying degrees of statistically significant (P<0.0001, P<0.001, P<0.05) changes to absorption band areas and shifts in centroid positions of peaks. Alteration patterns were similar to those induced by benzo[a]pyrene in MCF-7 cells. These findings have potential health implications for resident local communities as H. bidorsalis constitutes a key nutritional source. The study provides supporting evidence for the sensitivity of infrared spectroscopy in environmental studies and supports their potential application in biomonitoring.

Enhanced visible light photocatalytic activity of a floating photocatalyst based on B–N-codoped TiO2 grafted on expanded perlite

Floatable photocatalyst for in situ environmental remediation with enhanced visible light driven photocatalytic activity.

Bioframe synthesis of NF–TiO2/straw charcoal composites for enhanced adsorption-visible light photocatalytic degradation of RhB

N–F codoped TiO₂/straw charcoal composites (NF–TiO₂/SC) were synthesized using a simple, bioframe-assisted sol–gel method and confirmed by XRD, SEM, EDX, TEM, N₂ adsorption–desorption, Raman, FT-IR, XPS, and UV-vis DRS measurements.

Evaluation of alpha and gamma aluminum oxide nanoparticle accumulation, toxicity, and depuration in Artemia salina larvae

In this study, Artemia salina (crustacean filter feeders) larvae were used as a test model to investigate the toxicity of aluminum oxide nanoparticles (Al2O3 NPs) on marine microorganisms. The uptake, toxicity, and elimination of α-Al2O3 (50 nm and 3.5 μm) and γ-Al2O3 (5 nm and 0.4 μm) NPs were studied. Twenty-four and ninety-six hour exposures of different concentrations of Al2O3 NPs to Artemia larvae were conducted in a seawater medium. When suspended in water, Al2O3 NPs aggregated substantially with the sizes ranging from 6.3 nm to >0.3 µm for spherical NPs and from 250 to 756 nm for rod-shaped NPs. The phase contrast microscope images showed that NPs deposited inside the guts as aggregates. Inductively coupled plasma mass spectrometry analysis showed that large particles (3.5 μm α-Al2O3) were not taken up by Artemia, whereas fine NPs (0.4 μm γ-Al2O3) and ultra-fine NPs (5 nm γ-Al2O3 and 50 nm α-Al2O3) accumulated substantially. Differences in toxicity were detected as changing with NP size and morphology. The malondialdehyde levels indicated that smaller γ-Al2O3 (5 nm) NPs were more toxic than larger γ-Al2O3 (0.4 µm) particulates in 96 h. The highest mortality was measured as 34% in 96 h for γ-Al2O3 NPs (5 nm) at 100 mg/L (LC50 > 100 mg/L). γ-Al2O3 NPs were more toxic than α-Al2O3 NPs at all conditions.

Novel sensor technologies towards environmental health monitoring in urban environments: a case study in the Niger Delta (Nigeria)

The Niger Delta (Nigeria) is an exemplar of a legacy of environmental pollution. Limited knowledge on spatial and temporal pollutant distributions in the region highlights the need for biomonitoring approaches to study impacts on sentinel organisms. This study evaluated whether infrared (IR) spectroscopy and multivariate analysis could detect alterations in biomolecules in samples in differing exposure scenarios, i.e., spatial and temporal using African catfish (Heterobranchus bidorsalis) or water spinach (Ipomea aquatica). Significant spectral differences between tissues isolated from African catfish based on site or season were observed; in a region where fish appeared not to be present, water spinach was used as a surrogate sentinel organism. Using one-way ANOVA, the spectral categories were significant (P < 0.0001). The applicability of IR spectroscopy to detect subtle changes in target biological molecules within sentinel organisms along with its low-cost yet high-throughput potential suggests that biospectroscopy permits real-time evaluation of environmental exposure effects.

Metal-based nanoparticle interactions with the nervous system: the challenge of brain entry and the risk of retention in the organism

This review of metal-based nanoparticles focuses on factors influencing their distribution into the nervous system, evidence they enter brain parenchyma, and nervous system responses. Gold is emphasized as a model metal-based nanoparticle and for risk assessment in the companion review. The anatomy and physiology of the nervous system, basics of colloid chemistry, and environmental factors that influence what cells see are reviewed to provide background on the biological, physical-chemical, and internal milieu factors that influence nervous system nanoparticle uptake. The results of literature searches reveal little nanoparticle research included the nervous system, which about equally involved in vitro and in vivo methods, and very few human studies. The routes of uptake into the nervous system and mechanisms of nanoparticle uptake by cells are presented with examples. Brain nanoparticle uptake inversely correlates with size. The influence of shape has not been reported. Surface charge has not been clearly shown to affect flux across the blood-brain barrier. There is very little evidence for metal-based nanoparticle distribution into brain parenchyma. Metal-based nanoparticle disruption of the blood-brain barrier and adverse brain changes have been shown, and are more pronounced for spheres than rods. Study concentrations need to be put in exposure contexts. Work with dorsal root ganglion cells and brain cells in vitro show the potential for metal-based nanoparticles to produce toxicity. Interpretation of these results must consider the ability of nanoparticles to distribute across the barriers protecting the nervous system. Effects of the persistence of poorly soluble metal-based nanoparticles are of particular concern.

Study on Mechanism of Cross-Linking of Peanut Protein Isolate Modified with Transglutaminase

The mechanism of cross-linking of peanut protein isolate (PPI) modified with transglutaminase was investigated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and Fourier Transformation Infrared (FT-IR) spectra. SDS-PAGE banding patterns indicated that the contents of arachin and conarachin after transglutaminase (TGase) modification were decreased and high molecular weight polymers were formed. SDS-PAGE banding patterns also suggested that cross-linking effects were accomplished in the presence of transglutaminase and the main component participating in cross-linking was arachin. The representative FT-IR spectra of arachin, conarachin modified with TGase treatment appeared the sharp peak at 1680~1630cm-1 region, which showed that intramolecular cross-linking was occurred, respectively. Compared with FT-IR spectra of arachin, conarachin modified with TGase treatment, the spectra of PPI modified with TGase treatment appeared two characteristic absorption at 1546.29cm-1 and 1330.75cm-1, suggesting that cross-linking was occurred between arachin and conarachin and the ε-(γ-glutamyl) isopeptide bond generated.

A mixture of anatase and rutile TiO₂ nanoparticles induces histamine secretion in mast cells

Background

Histamine released from mast cells, through complex interactions involving the binding of IgE to FcεRI receptors and the subsequent intracellular Ca²⁺ signaling, can mediate many allergic/inflammatory responses. The possibility of titanium dioxide nanoparticles (TiO₂ NPs), a nanomaterial pervasively used in nanotechnology and pharmaceutical industries, to directly induce histamine secretion without prior allergen sensitization has remained uncertain.

Results

TiO₂ NP exposure increased both histamine secretion and cytosolic Ca²⁺ concentration ([Ca²⁺]_C) in a dose dependent manner in rat RBL-2H3 mast cells. The increase in intracellular Ca²⁺ levels resulted primarily from an extracellular Ca²⁺ influx via membrane L-type Ca²⁺ channels. Unspecific Ca²⁺ entry via TiO₂ NP-instigated membrane disruption was demonstrated with the intracellular leakage of a fluorescent calcein dye. Oxidative stress induced by TiO₂ NPs also contributed to cytosolic Ca²⁺ signaling. The PLC-IP₃-IP₃ receptor pathways and endoplasmic reticulum (ER) were responsible for the sustained elevation of [Ca²⁺]_C and histamine secretion.

Conclusion

Our data suggests that systemic circulation of NPs may prompt histamine release at different locales causing abnormal inflammatory diseases. This study provides a novel mechanistic link between environmental TiO₂ NP exposure and allergen-independent histamine release that can exacerbate manifestations of multiple allergic responses.