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Revealing graphene oxide toxicity mechanisms: a reactive molecular dynamics study

Summary

Graphene oxide (GO) is widely used in biotechnology because its oxygen functional groups increase hydrophilicity, but cytotoxicity mechanisms remain debated experimentally. Golkaram and van Duin report ReaxFF-based reactive molecular dynamics of GO interacting with peptide models in explicit water, isolating epoxide (–O–), hydroxyl (–OH), and carboxyl (–COOH) motifs before combining them. The abstract frames the study as the authors’ first atomistic-scale examination of GO toxicity chemistry, emphasizing bond-level pathways (e.g. reactive oxygen species, pH shifts, adhesion) rather than a single scalar dose metric.

Methods

MD application (ReaxFF): The authors build separate systems for each major GO functionalization (epoxide, hydroxyl, carboxyl) interacting with peptide segments in explicit water, then a combined model containing all groups (Mater. Discov. §2). Reactive MD with ReaxFF resolves bond-making/breaking at the GO–peptide interface on fs–ps timescales inside 3D PBC supercells. Ensemble: N/A — not stated on the indexed extract (typical aqueous biomolecular segments use NVT-class control; confirm in PDF). Barostat / bulk hydrostatic pressure: N/A — not the focus of the interface chemistry models summarized from the abstract. Timestep, thermostat type/damping, target temperature, total production time, and water/peptide stoichiometry: N/A — not transcribed from the short extract; read papers/Golkaram_MD_2016.pdf.

Force-field training: N/A — uses a published CHON ReaxFF referenced in the article (headline is application, not refit).

Static QM / DFT: N/A — not the primary method in the summarized framing.

Findings

The abstract states that different chemical reactions between GO and peptides can produce reactive oxidative species (ROS), drive acidic or basic pH conditions, and promote cell-surface adhesion (wording as printed in Mater. Discov.). It further reports strong hydrogen bonding together with stable π–π stacking between GO and peptide aromatics, with stacking implicated in disruption of polypeptide secondary structure. The Methods section (indexed text) adds that epoxide and carboxyl groups can catalyze thiol (–CSH) deprotonation and aldehyde → carboxyl conversion in the presence of ROS, whereas hydroxyl groups are tied primarily to secondary-structure denaturation and, through H-bonds to hydrophilic side chains, to enhanced adhesion (as discussed relative to prior experimental reports cited there). Quantitative rates, populations, and time-resolved product statistics are figure-specific and should be read from papers/Golkaram_MD_2016.pdf, not extrapolated from this note.

Limitations

The study reduces biological complexity to GO + peptide + water supercells rather than full membrane or cell models; the abstract explicitly notes that computational limitations hinder larger GO–protein systems that would capture tertiary structure and allosteric effects. GO polydispersity and in vivo corona chemistry are not fully represented.

Relevance to group

Penn State / van Duin-authored ReaxFF application extending reactive workflows to nanomaterial–biointerface questions.

Citations and evidence anchors

  • Journal header in papers/Golkaram_MD_2016.pdf lists Materials Discovery 1 (2015) 54–62; DOI: 10.1016/j.md.2015.10.001.