What Are Nanoparticles?
Nanoparticles are tiny particles that can be measured on a nanoscale (1 to 100 nm). These particles are extensively used in industrial activities and medical technologies because of their excellent physical and chemical properties, high penetration power, and large surface area, making them an ideal choice for various innovations, especially silver nanoparticles and fluorene. But these particles can potentially impact the environment and life on earth negatively by causing severe toxicity.
What Is Nanotoxicology?
Toxicity produced by the nanomaterials (NM’s) on the environment and health is studied under nanotoxicology, a branch of toxicology. Nanomaterials are mainly of four types, including:
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Carbon-based nanomaterials.
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Organic-based nanomaterials.
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Inorganic-based nanomaterials.
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Composite-based nanomaterials.
How Do Nanoparticles Enter the Body of Aquatic Organisms?
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Aquatic animals can mainly uptake and accumulate the nanoparticles through direct passage (across the gills) into the body or ingest the particles. However, they can also get exposed to the endocytosis process at the cellular level.
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Nanoparticles can get inside aquatic organisms through phagocytosis, endocytosis, and macropinocytosis. They can also enter the cell membrane via a transport or diffusion system and are found as free particles inside the cytoplasm.
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The silver nanoparticle widely used for commercial and industrial purposes is the silver nanoparticle which can enter the aquatic ecosystem through all routes and causes nanotoxicity to marine species.
What Are the Parameters to Measure Marine Toxicity by Nanoparticles?
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Exposure Media- It is an essential parameter in studying the toxicity of nanoparticles in the aquatic environment. It helps to determine whether the nanoparticles remain the same in all media or if there are any changes seen in their properties. The ionic strength and total water hardness affect the nanoparticle’s surface change and adherence to the tissue surface in aquatic media.
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Surface Chemistry- Various aspects of nanoparticles, like catalytic activity and cytotoxicity, are studied to understand the toxicology of the particles.
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Size and Surface Area- Nanoparticles are tiny (less than 100 nm) and show surface properties that can differ from larger particles of the same chemical composition. For example, smaller particles are more toxic as they can easily penetrate the cell membrane and tissues.
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Shape- Clustered nanoparticles are more toxic as compared to spherical forms.
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Concentration- High nanoparticle concentration in aquatic media causes damage to gills, embryonic development, and high mortality, whereas low concentration leads to physiological changes or other chromosomal defects.
What Are the Effects of Nanoparticles on Aquatic Organisms?
Effect on Fish:
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Studies show that fishes are susceptible to nanoparticles, especially the fish's gills which get affected easily. Fullerene exposure to the fish can cause lipid peroxidation in the brain. In some cases, death occurs within 6 to 8 hours after exposure to C60. Nanoparticles can damage the zebrafish (Danio rerio) gills, delay embryo hatching, cause malfunctioning in the embryo and larvae of zebrafish, and often lead to death.
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It has also been found that Fe2O3 aggregation and sedimentation in zebrafish can cause toxicity on the embryo’s body surface. In addition, Fe2O3 can also cause delayed hatching due to the direct absorption of the compound and interference with the digestive system.
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TiO2 nanoparticle exposure to rainbow trout (Oncorhynchus mykiss) can lead to respiratory disorders and penetrate the breast.testis, liver of medaka (Oryzias latipes).
Effect on Microorganisms:
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Microorganisms play a vital role in the aquatic ecosystem as they form the base of the ecosystem and help in significant processes such as maintaining the nutritional cycle and decomposition of waste products. Unfortunately, marine microorganisms are adversely affected by silver and titanium dioxide nanoparticles.
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Silver nanoparticles interact with the E.coli cell membrane and affect the transport and regulation process. In contrast, titanium dioxide causes solar disinfection in E.coli with the help of photocatalytic activity and reactive oxygen species.
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Energy metabolism is also affected by the fullerene nanoparticles.
Effect on Crustaceans:
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Crustaceans can hide away toxins or nanoparticles inside their body tissues. Fullerene can cause reproductive disorders in crustaceans and lead to a high mortality rate due to prolonged high exposure.
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Studies also show that nanoparticles (C60) have hydrophobic properties and thus adhere themselves to biological surfaces that are negatively charged, such as marine copepods (Acartia tonsa).
Effect on Mollusks:
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It was observed that nanoparticles could enter the body of mollusks and oysters and cause damage to the digestive system, affecting gills by breaking DNA (Deoxyribonucleic acid) strands.
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C60 fullerene can accumulate in oysters and cause damage to larvae development, and destabilize the digestive system's lysosomal activities.
Effect on Phytoplankton:
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The Accumulation and toxicity of nanoparticles on phytoplankton can affect the entire marine ecosystem because they are the primary producers in the food chain.
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Iron nanoparticles can inhibit phytoplankton growth.
Other Aquatic Organisms:
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Marine studies for nanotoxicology show the effect of nanoparticles in bivalve mollusks which target their immune function. Nanoparticles cause toxicity to the aquatic ecosystem and affect phagocytosis action, lysosomal activities, and increased apoptotic activity.
How Can Nanotoxicity Affect Aquatic Plants and Algae?
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Studies have not discussed the impact of nanoparticles on aquatic plants. However, silver nanoparticle toxicity is examined in some species by generation and bioaccumulation of reactive oxygen species.
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In another study, the activity of photosynthesis pigment and growth parameters were affected by exposure to nanoparticles.
Conclusion
Advancements in science and technology have increased the use of nanotechnologies in almost every field, showing a rapid growth in nanomaterials' production and manufacturing processes. Unfortunately, this has also led to the subsequent release of the nanoparticles into the environment causing damage to all the ecosystems, including the aquatic system. Scientists should hence explore further research based preventive measures to combat the damage of the marine ecosystems by these nanoparticles interaction as the marine ecosystem is indirectly linked to the welfare of human health and society.
