In vivo toxicity assessment of four types of graphene quantum dots (GQDs) using mRNA sequencing.

GQDs show great potential in drug carriers, bioimaging, biosensors, theranostics, and are recently reported as promising therapeutic agents to treat amyloid-related diseases such as Parkinson's disease and inflammations such as colitis. However, current toxicity data about GQDs based on in vivo toxicity assessments remain scarce. In the study, we examined the mRNA expression changes of zebrafish embryos exposed to four types of GQDs, including raw graphene quantum dots (R-GQDs), graphene oxide quantum dots (GOQDs), carboxyl GQDs (C-GQDs), and aminated GQDs (A-GQDs). Firstly, we treated embryos with the four GQDs at three concentrations (50, 100, and 200 μg/mL), and found that only A-GQDs caused embryonic developmental arrest at 100 and 200 μg/mL with significantly decreased survival rates and heartbeat rates, as well as the elevated malformation rates. Next, we analyzed the mRNA sequencing data acquired from zebrafish embryos exposed to the four GQDs for 7 days at 100 μg/mL, and found that all GQDs can act on potassium (K) and calcium (Ca) channels, and spliceosomes with varying degrees of regulatory effects. Compared to other GQDs, A-GQDs can strongly perturb the anticoagulant protein C (PC) pathway via activating most genes associated with complement and coagulation system, cell adhesion molecules (CAMs), and MAPK. In conclusion, this study provided substantial transcriptomic data underlying the common signaling pathways induced by various types of GQDs and pointed out the specific toxicity of A-GQDs on hemostatic system.