Silver nanoparticles (AgNPs) are widely used as engineered nanomaterials (ENMs) in many advanced nanotechnologies, due to their versatile, easy and cheap preparations combined with peculiar chemical-physical properties. Their increased production and integration in environmental applications including water treatment raise concerns for their impact on humans and the environment. An eco-design strategy that makes it possible to combine the best material performances with no risk for the natural ecosystems and living beings has been recently proposed. This review envisages potential hybrid solutions of AgNPs for water pollution monitoring and remediation to satisfy their successful, environmentally safe (ecosafe) application. Being extremely efficient in pollutants sensing and degradation, their ecosafe application can be achieved in combination with polymeric-based materials, especially with cellulose, by following an eco-design approach. In fact, (AgNPs)–cellulose hybrids have the double advantage of being easily produced using recycled material, with low costs and possible reuse, and of being ecosafe, if properly designed. An updated view of the use and prospects of these advanced hybrids AgNP-based materials is provided, which will surely speed their environmental application with consequent significant economic and environmental impact.

In this work, hydrophilic silver nanoparticles (AgNPs), bifunctionalized with citrate (Cit) and L-cysteine (L-cys), were synthesized. The typical local surface plasmon resonance (LSPR) at λ _max = 400 nm together with Dynamic Light Scattering (DLS) measurements ( = 8 ± 1 nm) and TEM studies (Ø = 5 ± 2 nm) confirmed the system nanodimension and the stability in water. Molecular and electronic structures of AgNPs were investigated by FTIR, SR-XPS, and NEXAFS techniques. We tested the system as plasmonic sensor in water with 16 different metal ions, finding sensitivity to Hg²⁺ in the range 1–10 ppm. After this first screening, the molecular and electronic structure of the AgNPs-Hg²⁺ conjugated system was deeply investigated by SR-XPS. Moreover, in view of AgNPs application as sensors in real water systems, environmental safety assessment (ecosafety) was performed by using standardized ecotoxicity bioassay as algal growth inhibition tests (OECD 201, ISO 10253:2006), coupled with determination of Ag⁺ release from the nanoparticles in fresh and marine aqueous exposure media, by means of ICP-MS. These latest studies confirmed low toxicity and low Ag⁺ release. Therefore, these ecosafe AgNPs demonstrate a great potential in selective detection of environmental Hg²⁺, which may attract a great interest for several biological research fields.

Marine nano-ecotoxicology has emerged with the purpose to assess the environmental risks associated with engineered nanomaterials (ENMs) among contaminants of emerging concerns entering the marine environment. ENMs’ massive production and integration in everyday life applications, associated with their peculiar physical chemical features, including high biological reactivity, have imposed a pressing need to shed light on risk for humans and the environment. Environmental safety assessment, known as ecosafety, has thus become mandatory with the perspective to develop a more holistic exposure scenario and understand biological effects. Here, we review the current knowledge on behavior and impact of ENMs which end up in the marine environment. A focus on titanium dioxide (n-TiO₂) and silver nanoparticles (AgNPs), among metal-based ENMs massively used in commercial products, and polymeric NPs as polystyrene (PS), largely adopted as proxy for nanoplastics, is made. ENMs eco-interactions with chemical molecules including (bio)natural ones and anthropogenic pollutants, forming eco- and bio-coronas and link with their uptake and toxicity in marine organisms are discussed. An ecologically based design strategy (eco-design) is proposed to support the development of new ENMs, including those for environmental applications (e.g., nanoremediation), by balancing their effectiveness with no associated risk for marine organisms and humans.

Surface coating plays a fundamental role in driving silver nanoparticle (AgNP) toxicity towards cells, but no clarity exists on the mechanism behind it. AgNPs with two different capping agents, citrate and L-cysteine (citLcys) and sodium-3-mercapto-1-propanesulfonate (3MPS), developed as sensors for metal ions in water (e.g., Hg(II) and Ni(II)), were investigated in terms of (eco)toxicity towards bacteria (Escherichia coli), microalgae (Raphidocelis subcapitata and Phaeodactylum tricornutum) and mammalian cells (HeLa and L929). After 72 h of incubation, Ag ion dissolution in algal media was negligible (<1% of nominal AgNP concentration) for both batches. Suspension in protein-rich media showed the formation of a protein corona around AgNPcitLcys as opposed to AgNP3MPS, which was confirmed by dynamic light scattering (DLS) analysis, transmission electron microscopy (TEM) and one-dimensional polyacrylamide gel electrophoresis (1D-PAGE). Low toxicity was observed for both AgNPs towards microalgae (≥5 mg L⁻¹) and E. coli (≥256 mg L⁻¹) and no effect was observed on HeLa and L929 cells. However, the responses suggest that citLcys coating might trigger the onset of a nano-size related toxicity as opposed to 3MPS, whose toxicity mainly relies on dissolution. Our findings show how surface coating rules AgNP interaction with biomolecules and drives AgNP (eco)toxicity towards cells, thus influencing exposure outcome.