Poster Presentations

Abstract of the Poster at International Nanotechnology Conference, 2017

Photosynthetic electron transport has been established to play important role in generation of silver nanoparticles (AgNPs). Present investigations were initiated to test if green microalge Chlorella minutissima and Chlamydomonas sp. can generate AgNPs when incubated in AgNO 3 solution in presence of sunlight. As anticipated AgNO 3 incubated with microalgae turned brown on exposure to sunlight, but not in dark, (giving a clue that photosynthetic events could be playing a role in generation of AgNPs). These brown colored colloidal suspensions showed absorption peaks in the UV-Vis absorption spectra arising due to surface plasmon resonance (SPR) specific to AgNPs. Transmission electron microscope (TEM) coupled with devices to measure selected area electron diffraction (SAED) and energy dispersive X-rays (EDX) patterns confirmed presence of ~10-30 nm spherical, crystalline nanoparticles composed of Ag in the brown colloidal suspensions. In order to test if photosynthetic machinery is involved in the generation of AgNPs, microalgae were suspended in methanol at ~65°C for 2h. The methanol extractable and methanol unextractable (devoid of photosynthetic pigments) components were incubated with AgNO 3 and exposed to sunlight to test their efficacy to generate AgNPs. AgNO 3-incubated independently with methanol extractable and unextractable components of microalgae also turned brown upon exposure to sunlight albeit to a significantly lower extent when compared to live cells. In summary, our investigations disclosed a simple, green and economically viable protocol for generation of AgNPs from AgNO3 by microalge Chlorella minutissima and Chlamydomonas sp. under ambient conditions in aqueous phase using sunlight. Conclusion Light play significant role in the synthesis of silver nanoparticles. The intact cell/ lives cells of algae showed higher potential for the synthesis of silver nanoparticles as compared to the methanol extract and aqueous suspension of methanol unextractable. Materials and methods Culture of microalgae Chlorella minutissima (MCC27) and Chlamydomonas used for present investigations. These microalgae were grown and maintained in BG11 nutrient medium. Experimental setup In order to test the potential of microalgae to generate silver nanoparticles Actively growing microalgae cells, methanol extractable and methanol unextractable were incubated with different concentration of silver nitrate and exposed in presence of sunlight and dark.