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Graphene Quantum Dots from Mangifera indica: Application in Near-Infrared Bioimaging and Intracellular Nanothermometry
journal contribution
posted on 2016-12-19, 00:00 authored by Mukesh
Kumar Kumawat, Mukeshchand Thakur, Raju B. Gurung, Rohit SrivastavaWe
report a simple one-pot microwave-assisted green-synthesis route
for the fabrication of bright red-luminescent graphene quantum dots
(GQDs) using ethanolic extracts of Mangifera indica (mango) leaves, hence addressing them as mGQDs. The mGQDs were quantum-sized
ranging from 2 to 8 nm and exhibited excitation-independent fluorescence
emission in the near-infrared (NIR) region between 650 and 750 nm.
The mGQDs showed defects in their structure and were highly crystalline
in nature as confirmed by Raman spectroscopy and powdered X-ray diffraction
analysis, respectively. These mGQDs showed 100% cellular uptake and
excellent biocompatibility on L929 cells even at high concentration
(0.1 mg/mL) 24 h post-treatment. Cell cycle analysis showed increased
proliferation in L929 cells upon mGQDs treatment. Furthermore, the
mGQDs were demonstrated as NIR-responsive fluorescent bioimaging probes,
self-localizing themselves selectively in the cell cytoplasm. Also,
the temperature-dependent fluorescence intensity of these GQDs proved
them as a very competent temperature sensing probe (at 10–80
°C). The temperature sensing stability analysis showed that the
temperature signal remains stable even after multiple cycles of temperature
switching between 30–80 °C. Furthermore, we analyzed intracellular
temperature (25–45 °C) of live L929 cells based on the
fluorescence intensity of the mGQDs. It was observed that with an
increasing temperature there was a decrease in the fluorescence intensity
of the mGQDs making it a suitable probe for temperature sensing. In
sum, a biocompatible, scalable, photostable, green synthesis based
mGQDs were prepared for NIR imaging and nanothermometry applications
which can play a pivotal role in biomedical nanotechnology.