Humanity today faces complex and wide-ranging challenges such as accelerating environmental degradation, climate change, and a growing demand for sustainable energy and food resources. Microalgae—particularly the valuable species Chlorella vulgaris—have emerged as a promising option for next-generation biofuel production as well as for nutritious food and supplements, owing to their high lipid content, rapid growth rates, and adaptability to diverse environmental conditions.
The present study innovatively examined the effects of graphene oxide (GO) and magnetic graphene oxide (MGO) on the growth and metabolism of Chlorella vulgaris cultured in seawater media from the Persian Gulf. A set of key indicators—including growth parameters, photosynthetic efficiency, and the synthesis of principal metabolites (lipids and proteins)—were assessed with high precision. The results showed that treatment with GO produced a significant increase in cell growth rate and biomass accumulation of more than ~10.5% .In addition, total chlorophyll in the presence of GO increased by 60–70%, indicating improved performance of the photosynthetic apparatus and more efficient light utilization. Notably, a GO concentration of 100 mg L⁻¹ was found to enhance CO₂ uptake capacity, a phenomenon attributed to GO’s high specific surface area and nanoporous structure.
Regarding metabolites, treatments containing 50 and 100 mg L⁻¹ of GO and MGO led to marked increases in lipid synthesis (18–50%), which is promising for biofuel production. However, the results also showed that MGO at comparable concentrations caused a substantial reduction in protein content (a 21% decrease at 100 mg L⁻¹ and up to a 77% decrease at 50 mg L⁻¹). This suggests that MGO may induce oxidative stress or alter metabolic pathways, thereby suppressing protein synthesis and diverting metabolite production toward lipids. These findings clearly indicate that selecting the type of nanomaterial and optimizing its concentration can be