Development and testing of Carbon Quantum Dot architectures to arrest neurotoxicant-insult- related outcomes

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Exposure to pesticides, fungicides and herbicides is linked to neuronal injury, neuronal loss and the onset and progress of neurodegeneration. Environmental and household use of pesticides such as rotenone, Maneb, paraquat, Cyprodinil, etc initiates mitochondrial dysfunction. The resulting elevation in levels of reactive oxygen species (ROS) and reactive nitrogen species (RNS) triggers ubiquitin-proteasome (UPS) dysregulation, alters cellular-proteomics’ status and the provokes the aggregation of amyloid proteins in neurons. Aggregation-prone amyloids such as alpha-synuclein, amyloid β, and mutant Huntingtin protein (mHTT) form toxic oligomers and protofibrils that create pores in cell membranes, disrupt Ca2+ homeostasis, facilitate neurotransmitter leakage and provoke neuronal death, on-setting neurodegenerative disorders such as Parkinson’s (PD), Alzheimer’s (AD) and Huntington’s (HD) diseases. Efforts at limiting environmental toxicant-driven neurodegenerative onset with small molecules have enjoyed limited success. Here, we explore whether a novel class of carbon nano materials, viz. carbon quantum dots (CQDs), can restore cellular homeostasis and prevent behavioral deficits in organisms under pesticide exposure. CQDs are easily synthesized from biowaste-containing carbon precursors such as fruit peel, waste paper and organic acids via green-chemical techniques. They possess low cytotoxicity and are inherently antioxidant. Importantly, they can be chemically functionalized and doped. When chemically tuned, they find applications in biosensing, tissue imaging, drug-delivery and can cross the blood-brain barrier. Preliminary data from our lab has revealed that organo-acid-derived CQDs can interfere in amyloid aggregation and mitigate ROS-stress in cells. They were uptaken by nematodes and protected them from paraquat toxicity. We hypothesize that CQDs ameliorate environmental toxicant- associated neuronal corruption. We test this hypothesis in Aim 1, by determining whether CQDs can intervene in amyloid fibril-forming trajectories. We also attempt to extend our understanding of how functionalized CQDs interact with toxic intermediates such as oligomers and protofibrils to passivate them. In Aim 2, using a number of proteomic and neurometabolomic readouts, we establish whether functionalized CQDs can reset pesticide-driven cellular dyshomeostasis in model neuroblastoma-derived cells. In Aim 3, we will test their ability to restore neuronal loss and behavioral deficits in C. elegans using strains prone to amyloidogenesis and/or via pesticide-exposure. In the former scenario, worms strains expressing mHTT, amyloid β or alpha-synuclein will be exposed to CQDs while the latter objective is completed by introducing CQDs into pesticide-challenged worms. By quantitatively co-relating amyloid aggregation and locomotor compromise with CQD-type and dose, we will test our hypothesis at the organismal level. Findings from the completion of the proposed work will define the ability of green-chemistry-derived CQDs to attenuate pesticide-associated neuronal corruption. CQDs are likely to translate to preclinical trials involving vertebrate (rodent) models of neurotoxic insult.