Cytotoxicity and Cellular Mechanisms of Novel Polymeric 2,4D Nanopesticide on Human Lung Epithelial A549 Cells

Nanotechnology offers promising ecosustainable solutions for crop protection, but the use of nanopesticides, such as 2,4-dichlorophenoxyacetic acid-loaded polymeric nanopesticides (2,4D-NPs), presents significant human health risks, particularly via inhalation. This study was carried out to assess the cytotoxicity and underlying mechanisms of 2,4D-NPs on human lung epithelial A549 cells, which were selected as a representative model for the primary site of inhalation exposure. The synthesized 2,4D-NPs were well-defined spherical particles with an average size of approximately 49 nm, a negative ζ potential, and high encapsulation efficiency, confirming successful nanoformulation. Cytotoxicity assessments showed that the 2,4D-NPs had a significantly enhanced effect compared to raw 2,4D, with an IC₅₀ of 72.63 ± 1.23 μg/mL at 24 h. The increase in toxicity was primarily driven by robust oxidative stress, evidenced by elevated reactive oxygen species (ROS) and malondialdehyde (MDA) levels, which led to severe mitochondrial dysfunction and depletion of adenosine triphosphate (ATP). The nanoparticles induced apoptosis, marked by increased cytochrome c release and caspase-3 activation, and exacerbated inflammation. Notably, no primary DNA damage was observed, underscoring that apoptosis and redox imbalance, not genotoxicity, were the main drivers of toxicity. Our findings provide a critical new blueprint for nanopesticide safety by demonstrating that the amplified cellular impact of 2,4D-NPs is mediated through specific pathways of redox imbalance and mitochondrial disruption. This moves the field forward by highlighting the need for a shift in safety assessments to include these mechanistic end points and by guiding the innovative engineering of safer agricultural nanomaterials.