Nannochloropsis Extract–Mediated Synthesis of Biogenic Silver Nanoparticles, Characterization and In Vitro Assessment of Antimicrobial, Antioxidant and Cytotoxic Activities

Document Type: Research Articles

Authors

1 Department of Pharmaceutical Biotechnology, Research Scholar, JNTUK, Andhra Pradesh, India.

2 Department of Pharmaceutical Sciences, Research Director, GIET School of Pharmacy, Rajahmundry, Andhra Pradesh, India.

3 Department of Marine Science, Bharathidasan University, Tiruchirappalli, Tamilnadu, India.

4 Department of Biomedical Science, Bharathidasan University, Tiruchirappalli, Tamilnadu, India.

5 Department of Pharmacology, AU College of Pharmaceutical Sciences, Andhra University, Vishakhapatnam, Andhra Pradesh, India.

Abstract

Objective: To investigate the biogenic synthesis of silver nanoparticles (AgNPs) using partially purified ethyl
acetate extract of Nannochloropsis sp. hexane (EAENH) fraction of microalga. Methods: The green synthesis of
AgNPs was confirmed with UV-Vis spectrum which shows the surface plasmon resonance (SPR) at 421 nm. Fourier
Transform Infrared Spectra (FTIR) presented the involvement of functional groups like carboxyl groups of fatty acids,
tetraterpenoids of xanthophylls, hydroxyl groups of polyphenols, carbonyl and amide linkage of proteins in the AgNP
synthesis. Gas Chromatography-Mass Spectrometry analysis (GCMS) revealed that phytochemicals like octadecanoic
acid and hexadecanoic acid imply in capping, bioreduction, and stabilization of AgNps. Result: High-resolution
Transmission electron microscope (HRTEM), Dynamic light scattering (DLS), X-ray diffraction (XRD) and EDX
analysis showed the crystalline form of the AgNPs with Z-average size 57.25 nm. The zeta potential value of -25.7
mV demonstrated the negative surface charge and colloidal stability of AgNPs. The antimicrobial activity of AgNPs
displayed effective inhibition zone against selected bacterial and fungal pathogens. In vitro, antioxidant effects were
assessed by 1,1-diphenyl-2-picryl-hydrazyl (DPPH), hydrogen peroxide and reducing power assays which revealed
excellent scavenging potential for AgNPs than the extracts. The anti-proliferative potential of biofabricated AgNPs
and extracts on Human Non-small lung cancer cell line (A549) was assessed using 3–(4,5-dimethylthiazol-2-yl)-2,5-
diphenyl-tetrazolium bromide (MTT) assay with IC50 values of 15 μgmL-1 and 175 μgmL-1 respectively. Conclusion:
The study reveals that the microalgae-mediated AgNPs possesses potent antimicrobial and antioxidant activity along
with the ability to stimulate apoptosis in A-549 cell line.

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