Green Synthesis of Blue-Emitting Graphene Oxide Quantum Dots for In Vitro CT26 and In Vivo Zebrafish Nano-Imaging as Diagnostic Probes

Abstract

Graphene oxide quantum dots (GOQDs) are prepared using black carbon as a feedstock and H2O2 as a green oxidizing agent in a straightforward and environmentally friendly manner. The process adopted microwave energy and only took two minutes. The GOQDs are 20 nm in size and have stable blue fluorescence at 440 nm. The chemical characteristics and QD morphology were confirmed by thorough analysis using scanning electron microscope (SEM), transmission electron microscope (TEM), atomic force microscope (AFM), Fourier transmission infra-red (FT-IR), and X-ray photoelectron spectroscopy (XPS). The biocompatibility test was used to evaluate the toxicity of GOQDs in CT26 cells in vitro and the IC50 was found to be 200 µg/mL with excellent survival rates. Additional in vivo toxicity assessment in the developing zebrafish (Danio rerio) embryo model found no observed abnormalities even at a high concentration of 400 μg/mL after 96 h post fertilization. The GOQDs luminescence was also tested both in vitro and in vivo. They showed excellent internal distribution in the cytoplasm, cell nucleus, and throughout the zebrafish body. As a result, the prepared GOQDs are expected to be simple and inexpensive materials for nano-imaging and diagnostic probes in nanomedicine.

Nanoengineering of Lanthanide‐Doped BaGdF5‐Graphene Oxide as a Tunable‐Nanocomposite Platform for Biological Applications

“…Our nanoparticles and their nanocomposite materials are designed for use within living organisms. Because in-vitro experiments cannot accurately reproduce the conditions found within a complete organism, [2,29,[34][35][36] therefore, it is difficult to make definitive statements about the overall biological compatibility of the nanoparticles based on in-vitro experiments alone. This prompted us to use zebrafish embryos as vertebrate-animal models to assess the biocompatibilities of our as-synthesized nanomaterials.…”

“…We further explored if GO could also modulate nanocomposite's biocompatibility properties in a dose‐dependent manner. As detailed insights about the comparative behavior of nanocomposite variants and their nanocomponents are challenging to achieve solely through in‐vitro studies because in‐vitro experiments cannot replicate the conditions present in the whole organism [2,29,34–36] . So, for biocompatibility assessment, we have used whole zebrafish larvae as vertebrate‐animal model in which craniofacial development, cardiac rhythm, and their overall survivability were used as sensitive biomarkers upon exposure to nanocomposites variants or their individual nanocomponents.…”

“…In the biomedical area, the novel nanoprobes made with inorganic metal-ions primarily serve as contrast agents in magnetic-imaging-based diagnostics applications e. g., CT/ MRI. [1][2][3][4][5][6][7][8][9][10] However, doping of lanthanide ions has allowed them in multimodal optical and magnetic-imaging-based diagnostics applications. [11][12] Interestingly, nanoprobes with Lanthanide (Ln 3 + ) doped ions have shown better capabilities for multimodal imaging than other inorganic or organic-based probes because they exhibit distinctive optical properties, such as significant Stokes shift, sharp emission band, high quantum yield, long lifetime, weak background luminescence and good resistance to photo-bleaching, blinking and photochemical degradation etc.…”

“…As detailed insights about the comparative behavior of nanocomposite variants and their nanocomponents are challenging to achieve solely through in-vitro studies because in-vitro experiments cannot replicate the conditions present in the whole organism. [2,29,[34][35][36] So, for biocompatibility assessment, we have used whole zebrafish larvae as vertebrate-animal model in which craniofacial development, cardiac rhythm, and their overall survivability were used as sensitive biomarkers upon exposure to nanocomposites variants or their individual nanocomponents. We found that GO exposure showed dose-dependent biocompatibility only when present in a nanocomposite and not when present alone as an independent nanocomponent.…”

“…In the biomedical area, the novel nanoprobes made with inorganic metal‐ions primarily serve as contrast agents in magnetic‐imaging‐based diagnostics applications e. g., CT/MRI [1–10] . However, doping of lanthanide ions has allowed them in multimodal optical and magnetic‐imaging‐based diagnostics applications [11–12] .…”