Silver and Titanium Dioxide Particles from Sea Sources Absorbed by Human Cells

Jim Crocker
11th March, 2025

Silver and Titanium Dioxide Particles from Sea Sources Absorbed by Human Cells

Dulse (Palmaria palmata), one the species mentioned.

Photo adapted from: Bernard Picton / CC BY (Source)

Key Findings

  • A University of Santiago de Compostela study found silver and titanium nanoparticles present in commonly eaten seaweed and mussels
  • Although up to 100% of these particles are available during digestion, less than 1% actually enters human cells
  • Cooking seaweed changes some nanoparticle forms, but overall absorption into the body remains very low
Engineered nanomaterials (ENMs) like silver nanoparticles (AgNPs) and titanium dioxide nanoparticles (TiO2NPs) are increasingly used in various industries, raising concerns about their presence in the environment and potential entry into the human food chain[2][3]. The University of Santiago de Compostela conducted a recent study[1] to investigate the bioaccessibility and bioavailability of these nanoparticles in commonly consumed seafood and seaweed, addressing important food safety issues. ENMs are utilized in products ranging from sunscreens and paints to food packaging and medical applications due to their unique properties. However, their widespread use leads to their release into aquatic environments, where they can accumulate in organisms such as algae and mussels[2]. Understanding how these nanoparticles interact with food sources is crucial for assessing potential health risks. The study focused on two types of ENMs: 15 nm polyvinylpyrrolidone-coated silver nanoparticles (PVP-AgNPs) and two sizes of citrate-coated titanium dioxide nanoparticles (TiO2NPs) measuring 5 nm and 25 nm. These nanoparticles were introduced to seaweed species (Palmaria palmata and Ulva sp.) and mussels (Mytilus edulis) at a concentration of 1.0 mg/L for 28 days. This exposure aimed to mimic environmental contamination and evaluate how these organisms accumulate and process the nanoparticles. Seaweeds and mussels are important components of the marine food web and are consumed by humans, making them relevant subjects for studying nanoparticle bioaccumulation[4]. Previous research has shown that different species of seaweed can accumulate varying levels of heavy metals, posing potential health risks[4]. Building on this, the current study examined not only the total concentrations of silver and titanium but also the specific nanoparticle forms within these organisms. After the exposure period, the samples underwent an in vitro digestion process that simulates human gastrointestinal digestion. This step is crucial because it helps determine how much of the ingested nanoparticles become bioaccessible, meaning available for absorption in the human digestive system[5]. The digested samples were then introduced to Caco-2 cell cultures, a model representing human intestinal cells, to assess the transport of nanoparticles from the intestinal lumen into the bloodstream. The researchers measured the total amounts of silver and titanium, as well as the fractions of nanoparticles that remained intact after digestion. They used advanced techniques like inductively coupled plasma mass spectrometry (ICP-MS) and single-particle ICP-MS (SP-ICP-MS) to accurately quantify these elements and nanoparticles. Additionally, single-cell ICP-MS (SC-ICP-MS) was employed to detect the presence of nanoparticles within the Caco-2 cells, providing insight into their potential to enter human cells. Results indicated that the bioaccessibility of AgNPs ranged from 22% to 97% in seaweed and was 18% in mussels. For TiO2NPs, bioaccessibility ranged from 17% to 81% in seaweed and was significantly higher in mussels, between 76% and 100%. Despite these high bioaccessibility rates, the actual transport of nanoparticles across the Caco-2 cell barrier was minimal, remaining below 1%. This suggests that while a considerable portion of nanoparticles becomes bioaccessible during digestion, their ability to enter human cells is limited under the experimental conditions. However, the study did find that a small percentage of silver and titanium existed in nanoparticle form within the Caco-2 cells when exposed to both raw and cooked seaweed. Specifically, 9% and 7% of silver and titanium, respectively, were present as nanoparticles in cells exposed to raw seaweed, and 20% and 6% in cells exposed to cooked seaweed. These findings highlight that cooking processes might influence the form and potential absorption of nanoparticles, although the overall transport remains low. This research builds on previous studies that have highlighted the environmental presence of ENMs and their potential uptake through the diet[2][3][5]. By focusing on bioaccessibility and bioavailability, the study provides a clearer picture of the actual risks posed by ingested nanoparticles. The minimal transport observed suggests that while nanoparticles are present in food sources, their likelihood of entering the human bloodstream is low, potentially mitigating some health concerns. Nonetheless, the study underscores the importance of continued monitoring and assessment of ENMs in food, especially as their industrial use continues to grow. The species-specific accumulation patterns observed also indicate that certain types of seaweed and seafood may pose higher risks, aligning with findings that different organisms accumulate heavy metals differently[4]. This information is vital for developing guidelines and regulations to ensure food safety in the context of increasing nanomaterial use. In conclusion, the University of Santiago de Compostela's study provides valuable insights into the behavior of silver and titanium dioxide nanoparticles in marine food sources and their potential impact on human health. By demonstrating low transport of these nanoparticles through intestinal cell models, the research offers some reassurance regarding the bioavailability of ENMs from consumed seafood and seaweed. However, it also highlights the need for ongoing research and careful evaluation of nanoparticle exposure through the diet to safeguard public health.

BiochemEcologyMarine Biology

References

Main Study

1) Bioaccessibility and cellular transport study of silver and titanium dioxide nanoparticles from exposed seaweed and mussels using Caco-2 cells

Published 8th March, 2025

https://doi.org/10.1007/s00604-025-07066-4

Related Studies

2) Reviews of the toxicity behavior of five potential engineered nanomaterials (ENMs) into the aquatic ecosystem.

https://doi.org/10.1016/j.toxrep.2017.04.001

3) Caco-2 in vitro model of human gastrointestinal tract for studying the absorption of titanium dioxide and silver nanoparticles from seafood.

https://doi.org/10.1016/j.talanta.2021.122494

4) Species-specific bioaccumulation and health risk assessment of heavy metal in seaweeds in tropic coasts of South China Sea.

https://doi.org/10.1016/j.scitotenv.2022.155031

5) Oral uptake of nanoparticles: human relevance and the role of in vitro systems.

https://doi.org/10.1007/s00204-016-1765-0


Related Articles

An unhandled error has occurred. Reload 🗙