Biocompatible Fluorescent Graphene Oxide Quantum Dots for Imaging of <i>Drosophila melanogaster</i>

Developing reliable biocompatible bioimaging agents is paramount for diagnosing critical diseases and disorders early through oral ingestion of fluorescent probes to image living organisms. Here, we prepared fluorescent, water-dispersed graphene oxide quantum dots <i>via</i> pyrolysis of a <i>Glycyrrhiza glabra</i> root in the water medium using a cost-effective and environmentally benign method to enable <i>Drosophila melanogaster</i>, an organism analogous to the human genome, to be imaged alive. The prepared graphene oxide quantum dots demonstrated a 2.6 nm diameter and 0.36 nm graphitic spacing with carboxylic acid, carbonyl, and hydroxyl functionalities. The selected area electron diffraction image analysis reveals a series of bright circular patterns that confirm the crystalline nature of the graphene oxide quantum dots. Raman and X-ray diffraction analyses also validate the crystallinity nature of prepared materials. The graphene oxide quantum dots exhibited blue fluorescence under ultraviolet-light irradiation with excitation-dependent emission properties from blue to red emission. The synthesized graphene oxide quantum dots consistently fluoresce in the larva-fed graphene oxide quantum dots without exhibiting toxicity. The current study evaluates the toxic effect of synthesized fluorescent graphene quantum dots by examining several screening and staining methods on <i>D. melanogaster</i>, a fruit fly, as a model.