Evaluation of nano-ZnOs as a novel Zn source for marine fish: importance of digestive physiology

Nano Iron Versus Bulk Iron Forms as Functional Feed Additives: Growth, Body Indices, Hematological Assay, Plasma Metabolites, Immune, Anti-oxidative Ability, and Intestinal Morphometric Measurements of Nile tilapia, Oreochromis niloticus

The current study aimed to compare the utilization efficiency of iron (Fe) feed additives from either bulk or nano sources in Nile tilapia, Oreochromis niloticus diets on growth, haematological, immunity, anti-oxidative, and intestinal topography capacities. Five isonitrogenous and isoenergetic diets were performed; the basal diet served as a control with no Fe added, whereas the experimental diets were shaped by adding bulk-Fe2O3 and nano-Fe2O3 to the basal diet to preserve Fe levels at 0.2 and 0.4 mg kg-1, respectively. Results indicated that superior growth performance was recorded in fish-fed diets supplemented with 0.4 nano-Fe2O3 mg kg-1 diet. In addition, the highest (P ≤ 0.05) survival rate, absorption area of villous (AAV), mucosal to serosal amplification ratio (MSR), and villi parameters (height and width) were noticed in fish fed diet enrichment with either bulk or nano-Fe2O3 source. However, the superiority observed in nano-Fe2O3 fish groups. Also, the highest values of plasma albumin, total protein, high-density lipoprotein cholesterol (HDL-C), white blood cells (WBCs), and lymphocyte absolute count (LYM) (P ≤ 0.05) recorded in fish fed a diet supplemented with nano-Fe2O3 versus the basal diet. Moreover, the highest values of catalase (CAT), glutathione peroxidase (GPx), superoxide dismutase (SOD), and plasma lysozyme activity (P ≤ 0.05) were observed in fish fed 0.4 mg/kg-1 nano-Fe2O3, while the lowest value was recorded in fish fed the control diet. The best value of malondialdehyde activity (P ≤ 0.05) recorded in a fish-fed diet supplemented with 0.4 mg/kg-1 nano-Fe2O3. The current findings emphasize the importance of including Fe to improve fish growth, immunity, antioxidant capabilities, and intestinal structure, primarily with a nano-Fe source, which demonstrated a more effective function in satisfying Nile tilapia dietary Fe requirements and improving the aforementioned parameters.

Chlorella vulgaris extract conjugated magnetic iron nanoparticles in nile tilapia (Oreochromis niloticus): Growth promoting, immunostimulant and antioxidant role and combating against the synergistic infection with Ichthyophthirius multifiliis and Aeromonashydrophila

Nile tilapia reared under intensive conditions was more susceptible for Ichthyophthirius multifilii (I. multifiliis) infection eliciting higher mortality, lower productive rate and further bacterial coinfection with Aeromonas hydrophila (A. hydrophila). The higher potency of magnetic field of iron oxide nanoparticles (NPs) can kill pathogens through inhibiting their viability. Herein, coating of Chlorella vulgaris extract (ChVE) with magnetic iron oxide NPs (Mag iron NPs) can create an external magnetic field that facilitates their release inside the targeted tissues. Thus, the current study is focused on application of new functionalized properties of Mag iron NPs in combination with ChVE and their efficacy to alleviate I. multifiliis and subsequent infection with A. hydrophila in Nile tilapia. Four hundred fingerlings were divided into: control group (with no additives), three groups fed control diet supplemented with ChVE, Mag iron NPs and ChVE@Mag iron NPs for 90 days. At the end of feeding trial fish were challenged with I. multifiliis and at 9 days post challenge was coinfected by A. hydrophila. A remarkable higher growth rate and an improved feed conversion ratio were detected in group fed ChVE@Mag iron-NPs. The maximum expression of antioxidant enzymes in skin and gills tissues (GSH-Px, CAT, and SOD) which came in parallel with higher serum activities of these enzymes was identified in groups received ChVE@Mag iron-NPs. Furthermore, group fed a combination of ChVE and Mag iron-NPs showed a boosted immune response (higher lysozyme, IgM, ACH50, and MPO) prior to challenge with I. multifiliis. In contrast, fish fed ChVE@Mag iron-NPs supplemented diet had lower infection (decreased by 62%) and mortality rates (decreased by 84%), as well as less visible white spots (decreased by 92 % at 12 dpi) on the body surfaces and mucous score. Interestingly, post I. multifiliis the excessive inflammatory response in gill and skin tissues was subsided by feeding on ChVE@Mag iron-NPs as proved by down regulation of IL-1β, TNFα, COX-2 and iNOS and upregulation of IL-10, and IgM, IgT and Muc-2 genes. Notably, group exposed to I. multifiliis-showed higher mortality when exposed to Aeromonas hydrophilia (increased by 43 %) while group fed ChVE@Mag iron-NPs exhibited lower morality (2%). Moreover, the bacterial loads of A. hydrophilia in fish infected by I. multifiliis and fed control diet were higher than those received dietary supplement of ChVE, Mag iron-NPs and the most reduced load was obtained in group fed ChVE@Mag iron-NPs at 7 dpi. In conclusion, ChVE@Mag iron-NPs fed fish had stronger immune barrier and antioxidant functions of skin and gills, and better survival following I. multifiliis and A. hydrophilia infection.

Synergistic Effects Between Dietary Zinc Form Supplementation and Dietary Protein Levels on Performance, Intestinal Functional Topography, Hemato-biochemical Indices, Immune, Oxidative Response, and Associated Gene Expression of Nile Tilapia Oreochromis niloticus

The present study investigates the effect of different dietary protein levels suboptimum level (25%) and optimum level (35%), different Zn forms bulk zinc oxide (BZnO) or nanoparticles zinc oxide (NZnO), and their interaction on performance, intestinal topography, hematology, serum biochemical, antioxidant-immune responses, and related gene expression of Nile tilapia. Six experimental diets were formulated to contain approximately 25% and 35% crude protein and supplemented with Zn forms with 0 (normal level in ingredients), 60 mg kg^-1 BZnO and 60 mg kg^-1 nanoparticles of NZnO. Nile tilapia, Oreochromis niloticus, fingerlings (7.53 ± 0. 06 g) were fed on one of tested diets in triplicates with 5% of total biomass three times a day for 84 days. Results showed that, fish fed diet containing 35% crude protein and supplemented with NZnO form recorded the highest final body weight (FBW), weight gain (WG), and specific growth rate (SGR). However, no significant (P > 0.05) differences were recorded in FBW, WG, SGR, feed conversion ratio (FCR), and protein efficiency ratio (PER) between fish fed diet containing 35% crude protein without Zn supplementation and fish fed diet containing 25% crude protein supplemented with NZnO form. Either fish fed diet containing 25% or 35% crude protein and supplemented with NZnO exhibited the highest values of villi height/width. The highest absorption surface area (ASA) was obtained in fish fed diet containing 25% or 35% crude protein and supplemented with BZnO. Hemoglobin (Hb), hematocrit (Hct), and red blood cell count (RBCs) highest values were obtained for fish fed diet containing protein level 35% supplemented with NZnO. Fish fed diet containing protein level 35% and supplemented with NZnO had the lowest value of alanine amino transferase (ALT) and aspartate amino transferase (AST). The highest globulin value was recorded for fish provided with diet containing 35% crude protein and supplemented with BZnO followed by those fed diet containing 35% crude protein and supplemented with NZnO. Fish fed diet containing protein level 25% with NZnO supplementation recorded the highest super oxide dismutase (SOD), catalase (CAT), glutathione reductase (GSH), and glutathione peroxidase (GP_X), with decreasing malondialdehyde (MAD) values. The highest values of immunoglobulin g (IgG), immunoglobulin M (IgM), complement 4 (C4), and complement 3 (C3) were obtained for diet containing 35% crude protein and supplemented with NZnO form. Growth hormone gene (GH) was upregulated in fish fed 25% dietary protein without Zn supplementation, while it was downregulated in fish fed 25% dietary protein and supplemented with NZnO. Transcription of insulin-like growth factor-1 (IGF-I) gene recorded the highest value for fish fed 35% crude protein and supplemented with BZnO. This is although the diet of 35% crude protein + NZnO induced significant (IGF-I) gene expression compared with 25% crude protein with or without BZnO. Therefore, nano zinc is useful as a feed supplement for Nile tilapia (Oreochromis niloticus).

Nano Zinc Versus Bulk Zinc Form as Dietary Supplied: Effects on Growth, Intestinal Enzymes and Topography, and Hemato-biochemical and Oxidative Stress Biomarker in Nile Tilapia (Oreochromis niloticus Linnaeus, 1758)

Five isonitrogenous diets were formulated to comprise two forms of zinc (Zn): convention zinc oxide named Bulk-ZnO or zinc oxide nanoparticles (Nano-ZnO) supplemented at two levels 30 and 60 mg kg^-1 compared to the control diet. Nile tilapia, Oreochromis niloticus, fingerlings (5.02-5.05 g) were fed tested diets two times a day for 84 days. The results displayed that the best growth and digestive enzyme activity (P < 0.05) were noticed in fish fed 60 mg kg^-1 Nano-ZnO. Moreover, significant (P < 0.05) improvement in intestinal topography was observed in 60 mg kg^-1 Nano-ZnO group versus other treatments. Furthermore, fish fed 30 mg kg^-1 Nano-ZnO recorded the best values of hematological indices (P < 0.05). The alanine and aspartate aminotransferase (ALT and AST) values were lower, while total serum protein, albumin, and globulin contents were clearly higher in fish fed diet that contained 30 mg kg^-1 Nano-ZnO versus other groups. The significant highest values of oxidative enzyme activity escorted with lower malondialdehyde value recorded of fish fed diet supplemented with 60 mg kg^-1 Nano-ZnO. The results indicated that inclusion of Nano-ZnO at 60 mg kg^-1 was the recommended source to enhance growth, feed utilization, amylase and lipase enzymes activity, intestinal morphology, hemato-biochemical, and oxidative response biomarkers of Nile tilapia compared with Bulk-ZnO in commercial tilapia feeds.

Mitochondria-Dependent Oxidative Stress Mediates ZnO Nanoparticle (ZnO NP)-Induced Mitophagy and Lipotoxicity in Freshwater Teleost Fish

Due to many special characteristics, zinc oxide nanoparticles (ZnO NPs) are widely used all over the world, leading to their wide distribution in the environment. However, the toxicities and mechanisms of environmental ZnO NP-induced changes of physiological processes and metabolism remain largely unknown. Here, we found that addition of dietary ZnO NPs disturbed hepatic Zn metabolism, increased hepatic Zn and lipid accumulation, downregulated lipolysis, induced oxidative stress, and activated mitophagy; N,N,N',N'-tetrakis (2-pyridylmethyl) ethylenediamine (TPEN, Zn²⁺ ions chelator) alleviated high ZnO NP-induced Zn and lipid accumulation, oxidative stress, and mitophagy. Mechanistically, the suppression of mitochondrial oxidative stress attenuated ZnO NP-activated mitophagy and ZnO NP-induced lipotoxicity. Taken together, our study elucidated that mitochondrial oxidative stress mediated ZnO NP-induced mitophagy and lipotoxicity; ZnO NPs could be dissociated to free Zn²⁺ ions, which partially contributed to ZnO NP-induced changes in oxidative stress, mitophagy, and lipid metabolism. Our study provides novel insights into the impacts and mechanism of ZnO NPs as harmful substances inducing lipotoxicity of aquatic organisms, and accordingly, metabolism-relevant parameters will be useful for the risk assessment of nanoparticle materials in the environment.

Dietary Nano-ZnO Is Absorbed via Endocytosis and ZIP Pathways, Upregulates Lipogenesis, and Induces Lipotoxicity in the Intestine of Yellow Catfish

Nano-sized zinc oxide (nano-ZnO) affects lipid deposition, but its absorption patterns and mechanisms affecting lipid metabolism are still unclear. This study was undertaken to investigate the molecular mechanism of nano-ZnO absorption and its effects on lipid metabolism in the intestinal tissues of a widely distributed freshwater teleost yellow catfish Pelteobagrus fulvidraco. We found that 100 mg/kg dietary nano-ZnO (H-Zn group) significantly increased intestinal Zn contents. The zip6 and zip10 mRNA expression levels were higher in the H-Zn group than those in the control (0 mg/kg nano-ZnO), and zip4 mRNA abundances were higher in the control than those in the L-Zn (50 mg/kg nano-ZnO) and H-Zn groups. Eps15, dynamin1, dynamin2, caveolin1, and caveolin2 mRNA expression levels tended to reduce with dietary nano-ZnO addition. Dietary nano-ZnO increased triglyceride (TG) content and the activities of the lipogenic enzymes glucose 6-phosphate dehydrogenase (G6PD), 6-phosphogluconate dehydrogenase (6PGD), and isocitrate dehydrogenase (ICDH), upregulated the mRNA abundances of lipogenic genes 6pgd, fatty acid synthase (fas), and sterol regulatory element binding protein 1 (srebp1), and reduced the mRNA expression of farnesoid X receptor (fxr) and small heterodimer partner (shp). The SHP protein level in the H-Zn group was lower than that in the control and the L-Zn group markedly. Our in vitro study indicated that the intestinal epithelial cells (IECs) absorbed nano-ZnO via endocytosis, and nano-Zn-induced TG deposition and lipogenesis were partially attributable to the endocytosis of nano-ZnO in IECs. Mechanistically, nano-ZnO-induced TG deposition was closely related to the metal responsive transcription factor 1 (MTF-1)-SHP pathway. Thus, for the first time, we found that the lipogenesis effects of nano-ZnO probably depended on the key gene shp, which is potentially regulated by MTF1 and/or FXR. This novel signaling pathway of MTF-1 through SHP may be relevant to explain the toxic effects and lipotoxicity ascribed to dietary nano-ZnO addition.

Impact of pH changes on metal oxide nanoparticle behaviour during artificial digestion

The physicochemical properties of orally ingested metal nanoparticles can be influenced by the conditions prevailing in the digestive tract. In our work, we demonstrate the strong influence of the pH value on particle fate using a simplified digestion approach to analyze magnesium oxide, copper oxide and zinc oxide nanoparticles and show why a separate consideration of the digestion parameters is necessary.

Engineered metal nanoparticles in the marine environment: A review of the effects on marine fauna

There is an increasing awareness of how damaging pollutants in the marine environment can be, however information on the effects of metal engineered nanoparticles (ENPs) on marine biota is still insufficient, despite an exponential rising in related publications in recent years. In order to provide an integrated insight on the present state of the art on metal ENP-related ecotoxicology studies on marine fauna, this review aimed to: (i) highlight the means of toxicity of metal ENPs in the marine environment, (ii) identify the principal biotic and abiotic factors that may alter metal ENP toxicity, and (iii) analyse and categorize results of these studies, including accumulation, molecular and histological biomarkers, genotoxicity and behavioural changes. Data retrieved from Scopus yielded 134 studies that met pre-established criteria. Most often, the target ENPs were titanium, zinc, copper or silver, and most studies (61.2%) focused on the phylum Mollusca. The degree of toxicity of metal ENPs was often dependent on the concentrations tested, length of exposure and the type of tissue sampled. Effects from simple tissue accumulation to DNA damage or behavioural alterations were identified, even when concentrations below environmentally available levels were used. It is proposed that other phyla besides the traditional Mollusca (and within it Bivalvia) should be used more often in this kind of studies, that exact pathways of toxicity be further explored, and lastly that co-stressors be used in order to best mimic conditions observed in nature. In this review, the current knowledge on engineered metal nanoparticles and their effects on marine fauna was summarized, highlighting present knowledge gaps. Guidelines for future studies focusing on under-developed subjects in ENP toxicology are also briefly provided.

Synthesis and Efficacy of the N-carbamoyl-methionine Copper on the Growth Performance, Tissue Mineralization, Immunity, and Enzymatic Antioxidant Capacity of Nile tilapia (Oreochromis niloticus)

Immunogenic, methionine copper-induced response had proven to be precedent in providing resistance against certain diseases in fish. This study allocates the fitness strategy for Oreochromis niloticus by introducing and incorporating the well-designed, stabilized, and biocompatible N-carbamoyl-methionine copper (NCM-Cu) as a Cu potent source in diet that enhances the bioavailability and fitness. The synchronized NCM-Cu complex was characterized by directing ultraviolet and visible spectrophotometry (UV-vis), Fourier-transform infrared (FTIR), X-ray diffractometry (XRD), thermogravimetric analysis (TGA), and single-crystal X-ray diffraction. Results revealed blue columnar crystalline, NCM-Cu complex with an empirical formula as C₁₂H₃₀CuN₄O₁₀S₂. Anonymously, the overall growth performance of the fish remained unaltered with NCM-Cu adjunct feed. NCM-Cu significantly raised the Cu accumulation in the fish muscles, liver, gill, and intestine in contrast to the basic Cu-rich feed. The serum antioxidant enzyme activity elevated up to (ceruloplasmin: 19.38 U/L) and the lowest liver malondialdehyde (MDA) content (8.81 nmol/mg prot.) and triglyceride content (0.39 nmol/g prot.) were observed in the NCM-Cu group as compared to the basic Cu and CuSO₄ groups, suggesting that NCM-Cu promoted antioxidative responses and alleviated lipid peroxidation of O. niloticus. Overweening, the synthesized complex, NCM-Cu significantly regulated the expression levels of lysozyme, immunoglobulin M, complement 4, and complement 3 up to 10.93 U/mL, 0.72, 0.77, and 1.18 mg/mL in serum, respectively. Thus, such endorsed results reveal the preeminence of NCM-Cu-supplemented diet for the fitness in O. niloticus.

Synthesis of Zinc Oxide Eudragit FS30D Nanohybrids: Structure, Characterization, and Their Application as an Intestinal Drug Delivery System

The present study was designed to develop multifunctional zinc oxide-encapsulated Eudragit FS30D (ZnO/EFS) nanohybrid structures as a biodegradable drug delivery system and as a promising successful carrier for targeting sites. The solvent evaporation method was used to fabricate the ZnO/EFS nanohybrids and the size, shape, stability, and antioxidant activity were characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS), thermogravimetric analysis (TGA), and an antioxidant (1,1-diphenyl-2-picrylhydrazyl (DPPH)). Zinc oxide-encapsulated Eudragit FS30D (ZnO/EFS) nanohybrid structures consisted of irregularly shaped, 297.65 nm-sized ZnO/EFS microcapsule, enduring thermal stability from 251.17 to 385.67 °C. Nano-ZnO was encapsulated in EFS through the formation of hydrogen bonds, and the average encapsulation efficiency for nano-ZnO was determined to be 96.12%. In vitro intestinal-targeted drug release assay provided 91.86% with free nano-ZnO, only 9.5% in acidified ZnO/EFS nanohybrid structure but the rate ZnO/EFS nanohybrids reached 93.11% in succus entericus resultantly modified nano-ZnO was proven proficient intestinal-specific delivery system. The stability of the ZnO/EFS nanohybrid structures was confirmed using ζ-potential and antioxidant activity analysis. Hence, the EFS nanoencapsulation strategy of ZnO provided a stable, nontoxic, and pharmacokinetically active intestine-specific system that can become the best choice for an effective oral feed additive in future.

Nano-Zn Increased Zn Accumulation and Triglyceride Content by Up-Regulating Lipogenesis in Freshwater Teleost, Yellow Catfish Pelteobagrus fulvidraco

The present study was conducted to explore the mechanism of nano-Zn absorption and its influence on lipid metabolism in the intestine of yellow catfish Pelteobagrus fulvidraco. Compared to ZnSO₄, dietary nano-Zn addition increased the triglyceride (TG) content, enzymatic activities of malic enzyme (ME) and fatty acid synthase (FAS), and up-regulated mRNA levels of 6pgd, fas, acca, dgat1, pparγ, and fatp4. Using primary intestinal epithelial cells of yellow catfish, compared to the ZnSO₄ group, nano-Zn incubation increased the contents of TG and free fatty acids (FFA), the activities of glucose-6-phosphate dehydrogenase (G6PD), 6-phosphogluconate dehydrogenase (6GPD), ME, and FAS, up-regulated mRNA levels of lipogenic genes (6pgd, g6pd, fas, dgat1, and pparγ), genes of lipid transport (fatp4 and ifabp), and Zn transport genes (znt5, znt7, mt, and mtf1), and increased the protein expression of fatty acid transport protein 4 (FATP4) and peroxisome proliferator activated receptor gamma (PPARγ). Further studies found that nano-Zn absorption was via the clathrin-dependent endocytic mechanism. PPARγ mediated the nano-Zn-induced increase in TG, and nano-Zn increased Zn accumulation and induced TG accumulation by activating the PPARγ pathway and up-regulating lipogenesis.

Oral bioaccessibility of silver nanoparticles and ions in natural soils: Importance of soil properties

The abundance of silver nanoparticles (AgNPs) in consumer products has led to their environmental release and therefore to concern about their impact on human health. The ingestion of AgNP-contaminated soil from urban sites is an important exposure pathway, especially for children. Given the limited information on oral bioaccessibility of soil Ag, we used a physiologically based extraction test (PBET) to evaluate the bioaccessibility of AgNPs and AgNO₃ from soil digestion. The AgNPs underwent several biochemical transformations, including their simultaneous dissolution and agglomeration in gastric fluid followed by the disintegration in the intestinal fluid of the agglomerates into NPs containing silver and chlorine. Therefore, Ag-containing soil exposed the intestine to nanoparticulate Ag in forms that were structurally different from the original forms. The bioaccessibility of AgNPs (0.5 ± 0.05%-10.9 ± 0.7%) was significantly lower than that of AgNO₃ (4.7 ± 0.6%-14.4 ± 0.1%), as a result of the lower adsorption of nanoparticles to soil residues during the digestive process. For the soils tested, the bioaccessibility of AgNPs increased with decreasing clay contents and lower pH. By identifying the soil properties that control AgNP bioaccessibility, a more efficient and accurate screening can be performed of soil types that pose the greatest health risk associated with AgNP exposure.