Improvement of growth and lipid accumulation in microalgae with aggregation-induced emission-based nanomaterials towards sustainable lipid production†

Microalgae are a hot research area owing to their promising applications for sustainable food, biofunctional compounds, and biofuel feedstock. However, low lipid content in algal biomass is still a challenge that needs to be resolved for commercial use. The current approaches are not satisfactory for achieving high growth and lipid accumulation in algal cells. This research aims to understand and evaluate the effects of light spectral shift on growth and lipid biosynthesis in a green microalga, Chlamydomonas reinhardtii. As a novel approach, an aggregation-induced emission luminogen (AIEgen), TPA-A (C₂₁H₁₉NO), was introduced into the culture media for tailoring the wavelength to a specific range to enhance photosynthesis and lipid production. Algal growth almost doubled at 10 μM TPA-A exposure compared to the control. A significant increase (*p < 0.05) in lipid accumulation was observed in the algal cells exposed to TPA-A. The elevated level of chlorophyll was attributed to fast algal growth. Furthermore, this luminogen was highly biocompatible (∼97% cell viability) on the HaCaT cell line at a concentration of 10 μM in under light conditions. No residues of TPA-A were detected after 7 days in culture media, indicating that this AIEgen was easily degradable. This AIE-based nanomaterial overcomes the conventional fluorophores’ aggregation-caused quenching effect by providing increased fluorescence with AIEgen. This approach for lipid induction with increased algal growth provides potential for the algal biofactory to produce sustainable bioproducts and eco-friendly biofuels.