nan Shweta

Uptake, Accumulation and Toxicity of Silver Nanoparticle in Autotrophic Plants, and Heterotrophic Microbes: A Concentric Review

Nanotechnology is a cutting-edge field of science with the potential to revolutionize today’s technological advances including industrial applications. It is being utilized for the welfare of mankind; but at the same time, the unprecedented use and uncontrolled release of nanomaterials into the environment poses enormous threat to living organisms. Silver nanoparticles (AgNPs) are used in several industries and its continuous release may hamper many physiological and biochemical processes in the living organisms including autotrophs and heterotrophs. The present review gives a concentric know-how of the effects of AgNPs on the lower and higher autotrophic plants as well as on heterotrophic microbes so as to have better understanding of the differences in effects among these two groups. It also focuses on the mechanism of uptake, translocation, accumulation in the plants and microbes, and resulting toxicity as well as tolerance mechanisms by which these microorganisms are able to survive and reduce the effects of AgNPs. This review differentiates the impact of silver nanoparticles at various levels between autotrophs and heterotrophs and signifies the prevailing tolerance mechanisms. With this background, a comprehensive idea can be made with respect to the influence of AgNPs on lower and higher autotrophic plants together with heterotrophic microbes and new insights can be generated for the researchers to understand the toxicity and tolerance mechanisms of AgNPs in plants and microbes.

Differential Phytotoxic Impact of Plant Mediated Silver Nanoparticles (AgNPs) and Silver Nitrate (AgNO3) on Brassica sp.

Continuous formation and utilization of nanoparticles (NPs) have resulted into significant discharge of nanosized particles into the environment. NPs find applications in numerous products and agriculture sector, and gaining importance in recent years. In the present study, silver nanoparticles (AgNPs) were biosynthesized from silver nitrate (AgNO3) by green synthesis approach using Aloe vera extract. Mustard (Brassica sp.) seedlings were grown hydroponically and toxicity of both AgNP and AgNO3 (as ionic Ag+) was assessed at various concentrations (1 and 3 mM) by analyzing shoot and root length, fresh mass, protein content, photosynthetic pigments and performance, cell viability, oxidative damage, DNA degradation and enzyme activities. The results revealed that both AgNPs and AgNO3 declined growth of Brassica seedlings due to enhanced accumulation of AgNPs and AgNO3 that subsequently caused severe inhibition in photosynthesis. Further, the results showed that both AgNPs and AgNO3 induced oxidative stress as indicated by histochemical staining of superoxide radical and hydrogen peroxide that was manifested in terms of DNA degradation and cell death. Activities of antioxidants, i.e., ascorbate peroxidase (APX) and catalase (CAT) were inhibited by AgNPs and AgNO3. Interestingly, damaging impact of AgNPs was lesser than AgNO3 on Brassica seedlings which was due to lesser accumulation of AgNPs and better activities of APX and CAT, which resulted in lesser oxidative stress, DNA degradation and cell death. The results of the present study showed differential impact of AgNPs and AgNO3 on Brassica seedlings, their mode of action, and reasons for their differential impact. The results of the present study could be implied in toxicological research for designing strategies to reduce adverse impact of AgNPs and AgNO3 on crop plants.

Plants and Carbon Nanotubes (CNTs) Interface: Present Status and Future Prospects

The unique characteristics of nanomaterials utilizing carbon have drawn great attention and interest since the breakthrough of fullerenes (in 1985), carbon nanotubes (CNTs, in 1991), and graphene (in 2004). This discovery has led to the promotion of developing methods in order to produce it at large industrial scales. Engineered nanomaterials are continuously finding its applications in medical sector, technical devices, environmental purposes, as well as agricultural sector. Despite its wide applications, there is also the unintended release of carbon-based nanostructures into the environment, thereby affecting or posing inimical effect toward the living systems like plants. The researchers are trying to engineer such nanoparticles in a way that it may impose some advanced and beneficial applications in living systems. One of the engineered carbon-based nanomaterials includes carbon nanotubes (CNTs) which can be further classified as single-walled carbon nanotubes (SWCNTs), multiwalled carbon nanotubes (MWCNTs), water-soluble multiwalled carbon nanotubes, functionalized single-walled carbon nanotubes, double-walled carbon nanotubes etc. This chapter, therefore, focuses on all aforementioned types of carbon nanotubes, techniques utilized in synthesis, and current status of research with respect to the impact of carbon nanotubes on plant growth and development addressing relevant knowledge gap.

Availability and Risk Assessment of Nanoparticles in Living Systems: A Virtue or a Peril?

Abstract Interaction of nanoparticles with living systems on earth has been occurring since ancient times, but as the technology increases each day, application of natural and anthropogenic nanoparticles also increases, which disturbs our ecosystem. Nanoparticles have a devastating effect on the environment by affecting directly or indirectly microbes, plants, and humans. In the era of increasing industrialization, nanoparticles have many advantages, but also many inevitable disadvantages. Their applications are so vast that they have become a part of our daily lives, for example, they are used in cosmetics, drugs, agriculture, electronics, etc.; however, when they are released in the environment, they cause deleterious effects. Thus to secure the environment, governments have devised a number of risk assessment and remediation plans to placate these effects on living organisms. In spite of this, scientists are trying to alter their role by increasing the quality of products to enhance the quality and quantity of crops by either supplying nanoparticles to the plants directly or by genetically modifying them. In this chapter, we have tried to summarize the positive and negative impacts of nanoparticles on living systems: plants, humans, and microorganisms.