title: Envelopment-Internalization Synergistic Effects and Metabolic Mechanisms of Graphene Oxide on Single-Cell Chlorella vulgaris Are Dependent on the Nanomaterial Particle Size.
abstract: The interactions between nanomaterials and cells are fundamental in biological responses to nanomaterials. However, the size-dependent synergistic effects of envelopment and internalization as well as the metabolic mechanisms of nanomaterials have remained unknown. The nanomaterials tested here were larger graphene oxide nanosheets (GONS) and small graphene oxide quantum dots (GOQD). GONS intensively entrapped single-celled Chlorella vulgaris, and envelopment by GONS reduced the cell permeability. In contrast, GOQD-induced remarkable shrinkage of the plasma membrane and then enhanced cell permeability through strong internalization effects such as plasmolysis, uptake of nanomaterials, an oxidative stress increase, and inhibition of cell division and chlorophyll biosynthesis. Metabolomics analysis showed that amino acid metabolism was sensitive to nanomaterial exposure. Shrinkage of the plasma membrane is proposed to be linked to increases in the isoleucine levels. The inhibition of cell division and chlorophyll a biosynthesis was associated with decreases in aspartic acid and serine, the precursors of chlorophyll a. The increases in mitochondrial membrane potential loss and oxidative stress were correlated with an increase in linolenic acid. The above metabolites can be used as indicators of the corresponding biological responses. These results enhance our systemic understanding of the size-dependent biological effects of nanomaterials.
authors.affiliation: †Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education)/Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China.
authors.forename: Shaohu
authors.initials: S
authors.lastname: Ouyang
authors.affiliation: †Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education)/Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China.
authors.forename: Xiangang
authors.initials: X
authors.lastname: Hu
authors.affiliation: †Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education)/Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China.
authors.forename: Qixing
authors.initials: Q
authors.lastname: Zhou
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects; D002462:Cell Membrane / Q000378:metabolism; D048408:Chlorella vulgaris / Q000166:cytology / Q000378:metabolism*; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D008401:Gas Chromatography-Mass Spectrometry; D006108:Graphite / Q000737:chemistry*; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D049329:Nanostructures / Q000737:chemistry* / Q000633:toxicity; D018384:Oxidative Stress / Q000187:drug effects; D010087:Oxides / Q000737:chemistry; D010316:Particle Size; D010539:Permeability / Q000187:drug effects; D045663:Quantum Dots / Q000737:chemistry / Q000633:toxicity; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D000596:Amino Acids; D010087:Oxides; D002734:Chlorophyll; D006108:Graphite; D000077194:Chlorophyll A
keywords: graphene oxide; metabolomics; nanotoxicology; quantum dot; reactive oxygen species; single cell