“Studies have been published in which seawater is used as the solvent or reaction medium for nanoparticle synthesis, excluding methods involving seaweed or algae.”

Regarding NP synthesis, several methods have been employed, including chemical, physical and biological approaches. Recently, the synthesis of NPs, more specifically metallic NPs (MNPs), has been achieved through the application of natural products from fungi, bacteria, plants and algae. This type of approach, known as green synthesis, is a simple, inexpensive and environmentally friendly method.

The ability of algae to accumulate metals and reduce metal ions make them a superior contender for the biosynthesis of nanoparticles. Whole cells of Plectonema boryanum (filamentous cyanobacteria) proved efficient in promoting the production of Au, Ag, and Pt nanoparticles. Synthesis of extracellular metal bio-nanoparticles using Sargassum wightii and Kappaphycus alvarezi has also been reported.

This study confirms the technical feasibility of the simultaneous electrosynthesis of high-value magnesium hydroxide and hydrogen from natural seawater. Benefiting from above, the synthesized NiFe2O4─HCOO─ delivers -1.0 A cm-2 at just 435 mV in alkaline seawater while maintaining exceptional stability over 1000 h and can be deployed in anion exchange membrane (AEM) electrolyzers with the technical and economic analysis (TEA) indicating the low cost of hydrogen production.

All operations including sampling, preparation, and detection should avoid plastics and use metal, glass, or ceramic materials. Relates to monitoring marine microplastics, not synthesis of nanoparticles using seawater.

Green-mediated nanoparticle synthesis is a low-cost, environmentally friendly method with no toxic properties. This method uses various stabilizing and reducing agents. Temperature, pressure, and energy are all used in the physical approach to obtain NPs. By the chemical method, NPs are obtained through sol–gel, atomic condensation, chemical etching, laser pyrolysis, spray-mediated pyrolysis, and sputtering.

The marine microbes have ability to synthesize nanoparticles as they exist in the bottom of sea and they are known to reduce huge amount of inorganic elements. The algae are aquatic oxygenic photoautotrophs which can be used in production of nanoparticles.

Direct seawater electrolysis (DSE) not only addresses this water resource challenge but also offers a potential solution for integrating deep-sea renewable energy sources. In this review, we first examine the challenges of DSE. Subsequently, we emphasize DSE technology and associated modification strategies, followed assessed the feasibility and economic viability of DSE.

This study investigates the effects of polystyrene nanoplastics (PS NPs) and elemental silicon nanoparticles (Si NPs) on the physiological and biochemical characteristics of Dunaliella salina, a halophilic alga. The nanoparticles are applied to algal cultures, but the synthesis of the nanoparticles themselves is not described as using seawater as the solvent or reaction medium; instead, the focus is on their impact on marine algae in saline environments.

Algae's unique photosynthetic electron transport chain can play an important role in synthesizing inorganic nanomaterials, and aquatic organisms like algae have strong adaptability to harsh environments, making algae promising 'nano-factories'. This review discusses microbial including algal extracts for nanoparticle synthesis, but does not mention seawater as the solvent excluding algae.

Marine seaweeds that belong to Chlorophyta, Rhodophyta, and Phaeophyta groups are reported to biosynthesize metal nanoparticles. Algae are relatively convenient to handle, less toxic, and less harmful to the environment; synthesis can be carried out at ambient temperature and pressure and in simple aqueous media at a normal pH value. There are three major techniques used for synthesis of nanoparticles using algae: direct exploitation of live algae cells, lysis of algal cells followed by extraction, and harvesting of nanoparticles from supernatants of algal broth.

Sea water is a harsh environment with high ionic concentration, which allows nanomaterial's (NMs) to change their behaviour dramatically. Rapid agglomeration, destabilization, and deposition may cause the NMs to disappear from surrounding water. Physical and chemical procedures for nanoparticles synthesis are extremely expensive. The scientific community targeted living entities in order to lower the unavoidable costs of downstream processing of produced NMs and to expand the use of nanoparticles.

The use of biological matter or renewable resources, for example, bacteria, fungi, algae, plant extracts, etc. in the green synthesis of metallic nanoparticles is reported widely. Using these extracts or living species is a fairly convenient and straightforward method of generating NPs on a large scale. These materials are collectively known as NPs of biogenic origin.

An international research team from Osaka University developed a green synthesis method for high-quality gold nanoparticles using microalgae extracts rich in reducing proteins, polysaccharides, and fatty acids as both reducing and stabilizing agents, without harmful chemicals. The synthesis uses algal extracts, not seawater itself as the solvent or reaction medium.

We report a scalable, single-step aqueous synthesis using a confined impinging jet mixer (CIJM) that produces size-controlled, clinically relevant nanoparticles, including silver sulfide, silver telluride, cerium oxide, and iron oxide, under ambient conditions. The method operates entirely in aqueous solutions at ambient temperature without the need for organic solvents.

Sargassum muticum, a species of brown seaweed commonly known as Japanese wireweed, has been used in the synthesis of gold and silver nanoparticles. To synthesise silver nanoparticles, which are the most widely used antimicrobial agent against bacteria, fungi, and viruses, Lynbyga majuscule, Spirulina platensis, and Chlorella vulgaris have been used. The reason for this success is the impressive ability of algae to accumulate and add electrons to metal ions on the cell surface using biomolecules.

This patent describes membranes functionalized with nanoparticles for ultrafiltration and water purification devices. Nanoparticles are used to functionalize membrane surfaces without reducing certain properties, but the preparation method does not specify seawater as the solvent or reaction medium for synthesizing the nanoparticles.

While most published studies on marine-based nanoparticle synthesis focus on algae and seaweed extracts, seawater itself contains dissolved salts, minerals, and organic compounds that could theoretically serve as a reaction medium. However, the primary literature emphasizes algae-mediated synthesis because algal biomass provides concentrated bioactive compounds (polysaccharides, proteins, phenolics) that are more efficient reducing and stabilizing agents than the dilute components naturally present in bulk seawater.

Using calcium alginate hydrogel, authors found that platelet-shaped poly(L-lactide)-based nanoparticles as adhesives provide better adhesion than spherical or cylindrical micelle nanoparticles. Involves seaweed-derived alginate hydrogel, but not seawater as solvent for nanoparticle synthesis excluding algae.

Rotifers that normally eat seaweed in Poyang Lake are ingesting plastics, producing up to 1.33×10^16 nanoplastics daily. Discusses nanoplastics in marine environments but not their synthesis using seawater as solvent.

Synthesis of nanoparticles through chemical methods which include coprecipitation method, sol-gel method and hydrothermal method. Co-precipitation involves precipitation of metal in the form of hydroxide from a salt precursor with the help of a base in a solvent. Hydrothermal method is performed at high vapor pressure level obtained from high temperature in aqueous solution. General chemical methods described; no specific mention of seawater as the solvent or reaction medium.

There are two methods for the synthesis of nanomaterials and the preparation of nanostructures. The top-down method refers to slicing or continuous cutting of bulk material to achieve nanosized particles. Chemical methods for nanoparticle synthesis are discussed generically without reference to seawater as solvent.

Nano membranes are used in nanotechnology to soften water and remove impurities like chemical, biological, and physical pollutants. Discusses application of nanoparticles in water purification, including seawater contexts, but no description of synthesizing nanoparticles using seawater as solvent.