Accentuating microalgae biorefinery cascade by sustainable synthesis of carbon dots from defatted Coelastrella sp. and piloting the antibacterial activity

In this study, carbon dots were synthesized using a green approach from defatted biomass of microalga Coelastrella sp. The entire process is extremely promising due to its non-toxic and environment-friendly nature. It demonstrated a sustainable approach for the biogenic synthesis of C-dots using lipid extracted biomass residue of microalgae Coelastrella sp. cultivated in distillery spent wash. The defatted algal biomass (DFB) was processed hydrothermally. The as-synthesized nanoparticles were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM), Fourier transform infrared (FT-IR)<bold>,</bold> and X-ray diffraction (XRD). Data showed the efficacy of microalgal metabolites in fabricating spherical, semi-crystalline C-dots with a size approximate to 7 nm with maximum absorption at a wavelength of 280 nm. Hence, this eco-friendly technique incorporates the use of defatted microalgae biomass for C-dots synthesis offering a potential alternative to chemically synthesized nanomaterials. Additionally, these synthesized C-dots were tested for their antibacterial activity against the gram negative bacteria. It was found that the green C-dots were capable of effectively inhibiting the bacteria at a concentration of 10 mg/mL. These findings imply that the defatted algae-derived C-dots have significant potential towards clinical and pharmacological applications, demonstrating that commercialization is a viable option. Nonetheless, dismounting the concerns about the synthesis of these materials such as the use of precursor chemicals and toxic solvents, the generation of toxic byproducts has led to a new alternative green synthesis approach, a way forward towards sustainable progress.