In this work, rice husk biomass was utilized as an abundant source to controllably prepare high-quality graphene quantum dots (GQDs) with a yield of ca. 15 wt %. The size, morphology, and structure of the rice-husk-derived GQDs were determined by high-resolution transmission electron microscopy, atomic force microscopy, and Raman spectroscopy. The as-fabricated GQDs can be stably dispersed in water, exhibiting bright and tunable photoluminescence. A cell viability test further confirmed that the GQDs possess excellent biocompatibility, and they can be easily adopted for cell imaging via a facile translocation into the cytoplasm. It is worth noting that mesoporous silica nanoparticles were also synthesized as a byproduct during the fabrication of GQDs. As such, our strategy achieves a comprehensive utilization of rice husks, exhibiting tremendous benefits on both the economy and environment.
Keywords: biocompatibility; cell imaging; comprehensive utilization; graphene quantum dots; rice husks.