Silver nanoparticles: mechanism of antimicrobial action, synthesis, medical applications, and toxicity effects

Sukumaran Prabhu,Eldho K Poulose

doi:10.1186/2228-5326-2-32

Abstract

Silver nanoparticles are nanoparticles of silver which are in the range of 1 and 100 nm in size. Silver nanoparticles have unique properties which help in molecular diagnostics, in therapies, as well as in devices that are used in several medical procedures. The major methods used for silver nanoparticle synthesis are the physical and chemical methods. The problem with the chemical and physical methods is that the synthesis is expensive and can also have toxic substances absorbed onto them. To overcome this, the biological method provides a feasible alternative. The major biological systems involved in this are bacteria, fungi, and plant extracts. The major applications of silver nanoparticles in the medical field include diagnostic applications and therapeutic applications. In most of the therapeutic applications, it is the antimicrobial property that is being majorly explored, though the anti-inflammatory property has its fair share of applications. Though silver nanoparticles are rampantly used in many medical procedures and devices as well as in various biological fields, they have their drawbacks due to nanotoxicity. This review provides a comprehensive view on the mechanism of action, production, applications in the medical field, and the health and environmental concerns that are allegedly caused due to these nanoparticles. The focus is on effective and efficient synthesis of silver nanoparticles while exploring their various prospective applications besides trying to understand the current scenario in the debates on the toxicity concerns these nanoparticles pose.

Highlights

The medical properties of silver have been known for over 2,000 years
This review provides an idea of the antimicrobial properties silver possesses as a nanoparticle, the various methods employed to synthesize silver nanoparticles, and an overview of their applications in the medical field and discusses the toxicity of silver nanoparticles
To understand the toxic potential nanosilver has on the freshwater environment, the Daphnia magna 48-h immobilization test was conducted, and the results showed that the silver nanoparticles have to be classified under ‘category acute 1’ as per the Globally Harmonized System of Classification and Labelling of Chemicals, suggesting that the release of nanosilver into the environment has to be carefully considered [88]

Summary

Introduction

The medical properties of silver have been known for over 2,000 years. Since the nineteenth century, silver-based compounds have been used in many antimicrobial applications. To understand the toxic potential nanosilver has on the freshwater environment, the Daphnia magna 48-h immobilization test was conducted, and the results showed that the silver nanoparticles have to be classified under ‘category acute 1’ as per the Globally Harmonized System of Classification and Labelling of Chemicals, suggesting that the release of nanosilver into the environment has to be carefully considered [88] Though these studies tend to suggest that nanosilver can induce toxicity to living beings, it has to be understood that the studies on nanosilver toxicity were done in in vitro conditions which are drastically different from in vivo conditions and at quite high concentrations of nanosilver particles. It is imperative that more studies be carried out to assess the toxicity effect nanosilver has in vivo before a conclusion on its toxicity is reached

Conclusions

68. Nano Bio Technology