(337bn) Nanotoxchip: A Novel Microfluidic Chip for Nanoparticle Safety Assessment

Abstract: Nanoparticles (NPs) exhibit notable features that are of great importance to various industries. A high ratio of surface area to volume, tunable composition and structure, high stability, and unique physical and chemical properties are among these features. These features facilitate the development of novel materials that exhibit enhanced functionality, thereby driving progress across diverse industrial domains spanning from cosmetics, coatings and paints to fuel and solar cells. NPs also play a crucial role in the pharmaceutical industry by dissolving, encapsulating, or entrapping active pharmaceutical ingredients (APIs) and serving as drug carriers and delivery systems. They offer advantages such as targeted, controlled, and sustained release, improved solubility and stability, and enhanced bioavailability of drugs, thereby creating new opportunities for drug development and delivery. However, it is crucial to assess the toxicity of NPs, to guarantee their safety in diverse applications and products. This assessment serves two key purposes: complying with regulatory standards and protecting both human health and the environment. The potential infiltration of NPs into aquatic systems, whether through wastewater discharge, spills, or products containing NPs, raises concerns. Moreover, the generation of NPs because of existing plastic contaminant degradation in the marine environment, also known as nanoplastics, adds to the apprehension. NPs can have detrimental effects on aquatic species and ecosystems, and they have the ability to accumulate in the food chain, eventually reaching humans. Therefore, a stringent assessment of nanoparticle safety is crucial, not only for the sustainable use of NPs in industries, but also to obtain information about the effects of extant NPs in the environment, particularly in marine settings. This paper describes a novel microfluidic chip that allows for the in-vivo evaluation of NP toxicity. The chip autonomously exposes lower trophic animals (prey) that have been exposed to NPs through the waterborne pathway to higher trophic animals (predators) to quantify the effect of multiple exposure routes and simulate the natural environment. Conventional NP toxicity assessment utilizes well plates, beakers, and fish tanks with static exposure conditions, which increases NP agglomeration, reduces bioavailability, increases fouling, and reduces dissolved oxygen for long-term tests. The large media volume in traditional toxicity assessment methods also creates difficulties in maintaining uniform environmental conditions including temperature, salinity, and dissolved oxygen; factors which affect the organisms directly and indirectly through changes in NP agglomeration and uptake. Conventional methods also necessitate human intervention to transport and immobilize the animal for analysis, which may impair the animal's physiological and neurological processes and limit data gathering to specific time intervals. To address these challenges, the developed microfluidic chip utilizes a continuous flow of NP-spiked water, maintains uniform environmental conditions, provides real-time, in-situ data on NP bioaccumulation in test animals via fluorescence microscopy, and on oxygen consumption or metabolic rate by monitoring changes in dissolved oxygen concentration via an on-chip optical oxygen sensor. Coryphaena hippurus (Mahi mahi), a commercially valuable species, was used as test marine animal in this study (predator), while the prey was Brachionus plicatilis, a rotifer. This study employed two distinct fluorescent polystyrene NPs that varied in size and color. The utilization of fluorescence microscopy revealed significant bioaccumulation of the NPs in the model organisms via both exposure pathways. Distinct trends were observed in the oxygen consumption behavior. In summary, the developed automated microfluidic chip can provide an in-situ, real-time assessment of nanoparticle safety under a controlled environment; it can also be used to evaluate the safety of other types of materials and chemicals.