Shellization Of Chlorella Cells By CeO₂ Nanoparticles And Studies On Its UV-resistance Property

Microalgae are the most widespread and fastest-growing photosynthetic organisms in nature.These organisms play important roles in solar-to-chemical energy conversion.Improving photosynthesis in these organisms can enable much more sustainable production of chemicals,providing elementary biomass for the energy industry.So they are considered as the most promising long-term,sustainable sources of biomass,with an indication of that algae will play important roles in overcoming the increasing energy demands and environmental concerns in the near future.However,the efficiency of photosynthesis of algae is extremely sensitive to environmental stresses.Ultraviolet（UV）radiation in the solar spectrum,a permanently existing environmental factor,can result in a significant inhibitory effect on the photosynthetic microalgae.Generally,the biological effects of UV radiation involve photosensitization and formation of toxic reactive oxygen species（ROS）,which is fatal to the microalgae.Studies have evidenced that the natural levels of UV radiation can significantly affect activities of relevant enzymes,damage DNA,reduce the levels of photosynthetic pigments and even destroy PSII structure of protein–pigment complex in algae,which may finally lead to the decrease of photosynthesis.Therefore,it is a great challenge to eliminate the biological damages caused by UV radiation.Inspired by biomineralization and shellization process in nature,we developed a one-step approach to construct cell-in-shell hybrid structure by directly using Ce O₂ nanoparticles.The engineered Ce O₂ nanoshell endow the Chlorella cell with ability to protect them from direct UV radiation due to their excellent ultraviolet filter property and it can also eliminate the oxidative stress which may be induced by UV radiation.Thus the resulted microalgae-Ce O₂ complex can guarantee its photosynthetic efficiency under UV.It follows a feasible strategy to protect living organisms by using functional nanomaterials.