(445e) Development and Potential Implications of the Use of Plasmonic-Based Technology in Microalgal Bio-Refinery

Development and potential implications of the use of plasmonic-based technology in microalgal bio-refinery

Abstract

In the context of renewable energy production, microalgae represent a promising viable and sustainable feedstock that can replicate the traditional refinery approach, often referred to as the bio-refinery. Through thermal and biochemical conversions, microalgal feedstock can be used to produce biodiesel, bioethanol, biohydrogen and other types of biofuels. Moreover, chlorophyll and carotenoid pigments from microalgae have several applications in food and pharmaceutical industries as food additives, cosmetic agents and antioxidants for medical purposes. Furthermore, algal extract is rich in proteins, carbohydrates and free amino-acids and can serve as a replacement for yeast extract used to feed microorganisms. However, commercial utilization of microalgae for such purposes is still far from being financially feasible due to high extraction costs and low productivity in confined environments. Therefore, strategies for improving algal biomass growth, carbohydrate and lipid production, as well as pigment accumulation have been extensively investigated.  

Recently, we initiated the use of plasmonic nanoparticles as a means to promote growth in microalgal culture. In this work a plasmonics-based technology was further developed to facilitate application to large scale algal biomass production. Specifically, thin polymer films consisting of spherical silver nanoparticles were fabricated and used as plasmonic filters that selectively enhance blue-green light absorption in microalgal cultures. Simultaneously, the effects of light enhancement due to localized surface plasmon resonance on microbial growth, dry biomass, lipid and carbohydrate production, as well as photosynthetic pigment accumulation were investigated. For the microalgal species Chlamydomonas reinhardtii, the use of plasmonic filters led to an increase in the microalgal dry biomass by more than 25% and an increase in chlorophyll and carotenoid pigments by more than 35%, compared to the control cultures without using these films after ten days of inoculation. Further, light enhancement by plasmon resonance did not affect lipid and carbohydrate accumulation within individual algal cells. However, higher cell densities obtained with plasmonic filters resulted in enhanced overall carbohydrate and lipid production. Adaptation of this plasmonics-based technology and its implications to large scale photo-bioreactor design is thoroughly discussed.