Marine Algae Growth and Carbon Capture Augmentation by Antioxidant Nanozymes: Article No. 104729

Large scale commercial cultivation of microalgae year-round is limited by seasonal stress conditions. The rapid growth and high CO2 capture of the marine microalga Picochlorum celeri is largely inhibited under winter stress conditions of low temperature and high light. Herein, we demonstrated a nanotechnology approach to enhance the biomass productivity and CO2 capture of P. celeri under abiotic stress by interfacing with antioxidant cerium oxide nanozymes (nanoceria). Antioxidant nanoceria catalytically scavenged reactive oxygen species (ROS) generated under stress conditions, reducing damage to the microalgae photosynthetic machinery in chloroplasts. Negatively charged poly-acrylic acid-coated nanoceria (PNC, 10 ..mu..M) were biocompatible in microalgae cells and colocalized with chloroplasts. In contrast, positively charged aminated nanoceria (ANC) resulted in microalgae aggregation (>50 ..mu..M) and were toxic at all concentrations tested (>=10 ..mu..M). PNC reduction of ROS levels in microalgae (78%) and superoxide levels (26%), enhanced microalgae growth (65%), photosynthetic performance (130%), and CO2 uptake rate (380%) under low-temperature stress (15 degrees C) and high light (500 ..mu..mol/m2/s PAR) stress relative to controls without nanoceria. Nanoceria augmentation of microalgae provides a rapid and facile technology to increase algae CO2 capture and biomass under stress conditions.