Green and Chemical Syntheses of CdO NPs: A Comparative Study for Yield Attributes, Biological Characteristics, and Toxicity Concerns.

Madeeha Nasrullah,Saad Hanif,Sania Naz,Faiza Zareen Gul,Abdul Mannan,Joham Sarfraz Ali,Muhammad Zia

doi:10.1021/acsomega.9b03769

Madeeha Nasrullah, Saad Hanif + Show 5 more

Open Access

https://doi.org/10.1021/acsomega.9b03769

Copy DOI

Abstract

Metallic nanoparticles (NPs) have enormous applications due to their remarkable physical and chemical properties. The synthesis of NPs has been a matter of concern because chemical methods are toxic. On the contrary, biological methods are considered eco-friendly. To compare the toxicity and the environment-friendly nature of the synthesis methodologies, cadmium NPs were synthesized through chemical (Ch) (co-precipitation) and biological (plant extracts as reducing agent) methods. Cadmium nitrate was reduced with NaOH, while in the biological method, the Cd ions were reduced by Artemisia scoparia (As) and Cannabis sativa (Cs) extracts. X-ray diffraction (XRD) analysis confirmed the pure single-phase cubic structure of green and chemically synthesized CdO NPs except As-CdO NPs that were crystalline cum amorphous in nature. The size of nanoparticles was 84 nm (Cs-CdO NPs) and 42.2 nm (Ch-CdO NPs). The scanning electron microscope (SEM) images exhibited an irregular disklike morphology of nanoparticles that agglomerated more in the case of green synthesis. The antioxidant and antimicrobial potential of NPs revealed that chemically synthesized NPs have better antimicrobial capability, while the antioxidative activities were better for green-synthesized NPs. However, the low yield, high ion disassociation, and waste (unreacted metal) production in the green synthesis of CdO NPs increase the risk of contamination to biosphere. Both types of NPs did not affect the seed germination of Dodonaea viscosa. However, chemically synthesized NPs were less toxic on plant morphological response. The study concludes that the chemically synthesized CdO NPs have better morphology, significant antimicrobial activity, and less toxicity to plant species compared to green-synthesized NPs. Moreover, during the green synthesis, unreacted metals are drained, which causes contamination to the ecosystem.

Highlights

Manipulation of matter to size less than 100 nm with at least one dimension changes the chemical and physical properties of a substance
This study identifies any possible difference in the properties, yield, and toxicity of CdO NPs and the concentration of metal and waste synthesized through green and chemical routes, as well as determines the better route for the synthesis of CdO NPs on the basis of biological and toxicological studies
The reducing agent NaOH and biomolecules, i.e., phenolics, flavonoids, alkaloids, proteins, etc., in the case of plant extracts, are capable of reducing the metal into NPs. The reduction in this case depends upon the choice of plant for extract preparation and the extraction methodology because each plant and method have their own biochemical and phytochemical properties. This is the reason that Artemisia scoparia (As)-CdO NPs were crystalline cum amorphous while CsCdO NPs were crystalline in nature

Summary

Introduction

Manipulation of matter to size less than 100 nm with at least one dimension changes the chemical and physical properties of a substance. Nanoparticles (NPs) are synthesized by biological, chemical, and physical methods. Biosynthesis encompasses the natural reduction property catalyzed by biomolecules in plants and microorganisms to transform metal ions into metal NPs. In 2019, more than 17 000 publications are focused on the green synthesis of nanoparticles, and this number is rising continuously. Variability in plants used for extract preparation is a major limiting factor to standardize conditions for the green synthesis of NPs due to variations in the type and concentration of biomolecules. Plant-mediated green synthesis is considered cost-effective, simple, rapid, and eco-friendly regardless of the low yield of NPs.[1] Quality, size, and morphology of green-synthesized NPs are influenced by various factors, including pH, temperature, reaction time, and concentration of metal salt.[2]

Methods

Results

Conclusion