Green synthesis and characterization of La2O3 nanoparticles using Eclipta prostrata and its antibacterial activity

Abstract

Advances in the field of nanoscience and nanotechnology to modulate materials at nanoscale level has continued to have great impact on different disciplines of science and engineering as well as agriculture and medical fields. Metallic and metal-oxide nanostructures have shown great potential due to their high surface to volume ratio and high reactivity. Among them, LaO has revealed wider applicability, including in nanomedicine, where LaO nanomaterials have shown great potential leading to effective interactions with biological membranes and exhibiting antibacterial and/or anticancer behaviors. In the current study, the **biosynthesis **of La2O3 NPs was attained by a biosynthesized method by using the aqueous leaf extract of Eclipta prostrata. La2O3 NPs were characterized by UV, FTIR, XRD, SEM, FL, PSA and TGA methods. The X-ray diffraction displayed the existence of La2O3 NPs which is confirmed by the incidence of peaks at 28.32 corresponds to 002 anatase form. The La2O3 NPs showed significant antimicrobial activity against all the tested microorganisms.

Introduction

The use of biomolecules presents in plant extracts to reduce metal ions to nanoparticles in a single-step green synthesis process has been found to be cost effective and eco-benign over the physical and chemical methods. Development of bioinspired material for fabrication of nanoparticles is the cutting edge of research and is a suitable process for largescale production (Kalishwaralal et al., 2018, Anuradha et al., 2014). Among the living organisms, the plant materials gain more attention in the nanoparticle production. In recent years, developments of nanotechnology field have triggered increased interest in using the unique properties of nanomaterials for environmental applications (Narayanan et al., 2004). LaO NPs synthesis has attracted particular interest, compared with other NPs, as their useful properties are achievable at costs lower than silver and gold (Zhang et al., 2013). Research into LaO NPs has made significant progress in the areas of nanotechnology and nanomedicine within the last decade due to their excellent catalytic, optical, electrical and antifungal/antibacterial applications (Han et al., 2006, Ponce et al., 2005). In addition, the plant-mediated synthesis was found to be rapid, flexible, and suitable process for large-scale nanoparticle production. Plant parts like fruit (Huang et al., 2008), leaf (Ankamwar et al., 2005), bark (Narayanan et al., 2004), seed (Sathishkumar et al., 2009), and stem (Bar et al., 2009) extracts are being effectively used in green synthesis.

Eclipta prostrata (syn. Eclipta alba) commonly known as false daisy, yerba de tago, and bhringraj, is a species of plant in the family Asteraceae. Other common names include kehraj in Assamese and karisalaankanni in Tamil (Daisy et al., 2012, Kritikar et al., 1975). This plant has cylindrical, grayish roots. The solitary flower heads are 6–8 mm in diameter, with white florets. The achenes are compressed and narrowly winged. This species grows commonly in moist places as a weed in warm temperate to tropical areas worldwide. It is widely distributed throughout India, China, Thailand, and Brazil (Chopra et al., 1955, Thorat et al., 2010). Therefore, the present investigation was aimed to green synthesized La2O3 NPs using Eclipta prostrata leaf extract. The synthesized La2O3 NPs to assess its antimicrobial activity against S. aureus, Enterobacter, Psedomonous, Bacillus and E. coli (Prakash et al., 2011). Henceforth, this method could be appropriate for evolving a biological method for mass scale generation of nanoparticles.

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