Fabrication of innocuous gold nanoparticles using plant cells in culture

Sinilal Bhaskaran,Pooja Tiwari,Shivendra V Sahi,Nilesh Sharma,Shree R Singh

doi:10.1038/s41598-019-48475-9

Abstract

Plant extracts and their different growth phases have been manipulated for the fabrication of nanomaterials, which can be an eco-friendly alternative to the chemical methods that produce hazardous by-products. However, practical difficulties in isolation of the nanoparticles obtained through biological methods and the scanty control that these methods allow over their shapes and sizes impose limitations in their utility. For the first time, we report here a versatile system using cell suspension culture of Medicago sativa, which ensures control over the reaction to regulate size of the particles as well as their easier recovery afterwards. Isolated nanoparticles were characterized for their shape, size and functions. The particles varied in shapes from isodiametric spheres to exotic tetrahedrons, pentagons and pentagonal prisms. They clearly demonstrated catalytic activity in the reduction reaction of methylene blue by stannous chloride. Interestingly, the cell culture-derived particles were found less cytotoxic to healthy human cell line HEp-2 while more cytotoxic to the cancer cell line 4T-1 in comparison to those synthesized through citrate method. However, when administered in mice, these nanoparticles elicited similar inflammatory responses as those produced by chemically synthesized counterparts. These results envisage the utility of these particles for various biological applications.

Highlights

Conventional preparative techniques for synthesis of Gold Nanoparticles (AuNPs) employ physical and chemical methods
Even though the AuNPs synthesized in cell culture are similar in their chemical and metallic nature to those synthesized by citrate method, their surface chemistry can vary since they are synthesized by the biomolecules inside Medicago cells
M. sativa cells in suspension to KAuCl4 was determined by exposing the culture to its various concentrations (10–200 ppm)

Summary

Introduction

Conventional preparative techniques for synthesis of Gold Nanoparticles (AuNPs) employ physical and chemical methods. A notable comparative study involving several species indicated that M. sativa possesses characteristics such as an increased uptake potential and reduced toxicity response toward heavy metals including gold, which may be advantageous for devising a plant-based fabrication system for nanomaterials[5]. Growing plants under controlled conditions for fabrication and further processing for recovery of particles from the huge matrix of plant tissue is laborious In this backdrop, utilization of cell suspension culture derived from the plant could be advantageous for both induction and isolation of the particles. Morphological and anatomical characteristics in addition to the molecular traits of a plant species may be implicated in the unusual potential for hyperaccumulation of heavy metals[11,12] It is not known whether intact cells growing suspended in liquid medium can retain the above features. As administration of commercially available AuNPs has been shown to trigger immunological responses (such as antibody and cytokine secretion) in mammalian hosts[16], the cell-derived AuNPs were tested in this investigation for their effects using a murine model of inflammation

Methods

Results

Conclusion