Project Materials

ANTIBACTERIAL EVALUATION OF AFANG LEAF EXTRACT AND IT’S SYNTHESIZED SILVER NANOPARTICLES

CHAPTER ONE

LITERATURE REVIEW 

Background of the Study 

In recent years, a lot of research has been conducted on nanoscience. Researchers from a variety of scientific and technological disciplines have investigated it (Kholoud et al. 2010).

This field of study has received a lot of attention because of the novel properties of NPs, which have been used in a variety of potential applications, including biomedical devices, electronics, optics, organic catalysis, vector control, sensors, renewable energies, medicine, cosmetics, and environmental remediation (Quang Huy, 2013). (Mousavand et al. 2007).

Among the metals, silver nanoparticles have demonstrated potential uses in a number of domains, including electronics, biomedicine, optics, catalysis, and the environment (Rao et al., 2000).

About 20–15,000 silver atoms make up silver nanoparticles, which are typically smaller than 100 nm. Silver has special physicochemical and biological properties when it is at the nanoscale.

According to Elemike et al. (2014), Vinod et al. (2014), Kathiravan et al. (2014), Saraschandra and Sivakumar (2014), Namita and Soam (2014), and others, this has made them valuable as sensors, vector control, antibacterial, anticancer, and antiplasmodial agents, and catalysts.

Because of their potential uses, especially in electronics (P. V. Kamat, 2002), electrochemical sensing (L. M. Liz-Marzán, 2006), catalysis (F. Zhang, Y. Pi et al., 2007), and antimicrobial properties (T. Sakai et al., 2006), a concerted effort has been made to synthesise a diverse range of silver nanoparticles varying in size, geometry, and morphology.

The appropriateness of the nanoparticles for certain applications is frequently determined by their size, shape, dispersion, and stability. The process of synthesis can be carried out biologically using plant extract, microorganisms, or plant sap, or physically using UV radiation, microwaves, photo-reduction, or chemical reduction utilising hydrazine, ascorbic acid, sodium borohydride, glucose, and organic stabilisers.

Silver nanoparticles have been created and stabilised using a variety of physical and chemical techniques (Senapati et al., 2005, Klaus-Joerger et al., 2001).

The most extensively used chemical methods for creating nanoparticles are physicochemical reduction, radiolysis, electrochemical methods, and chemical reduction with various organic and inorganic reducing agents.

The demand for environmentally safe, nontoxic synthetic procedures for the synthesis of nanoparticles stems from the fact that, despite their speed and ease, these methods are either costly or poisonous, especially the chemical technique, and may produce unfriendly byproducts. “Green” chemistry and chemical processes are gradually integrating with contemporary scientific and industrial advancements in the global endeavour to reduce generated hazardous waste (Sharma et al., 2009).

This has led to a growing interest in biological approaches that do not utilise toxic chemicals as byproducts. It is possible to create nanoparticles using biological processes instead of harsh, costly, and toxic chemicals.

The bioreduction of metal ions by combinations of biomolecules found in the extracts of certain species (e.g., enzymes/proteins, yeast, fungi, bacteria and plants) is environmentally benign, although chemically complex (Ankamwar et al., 2005).

The ability of biomolecules with amine, hydroxyl, and carbonyl functional groups to reduce metal ions and cap freshly generated particles throughout their growth processes has been clarified (Harekrishna et al., 2009, He et al., 2007).

Essential oils (terpenes, eugenols, etc.), polyphenols, carbohydrates, etc., are biomolecules found in plant and spice extracts that have the ability to stabilise and lower Ag+ to Ag0. Because it is economical and environmentally friendly, it offers an improvement over chemical and physical methods.

1.1 LITERATURE REVIEW

Microbes that cause disease are become more resistant to medication, which presents a serious public health concern. Due to the rise in microbial species that are resistant to several antibiotics, numerous researchers are currently working to create new, efficient antimicrobial reagents, which will raise the expense of healthcare. Colloidal silver’s antibacterial qualities, non-toxicity, and environmental friendliness have long been recognised.

For many years, it has been used in the medical field for antimicrobial purposes, including the treatment of burns (Parikh et al. 2005; Ulkur et al. 2005), the removal of microorganisms from textile fabrics (Jeong et al. 2005; Lee et al. 2007; Yuranova et al. 2003), disinfection in water treatment (Russell and Hugo 1994; Chou et al. 2005), the prevention of bacterial colonisation on catheters (Samuel and Guggenbichler 2004; Alt et al. 2004; Rupp et al.

2004), Additionally, it has been shown to stop HIV from attaching itself to host cells (Sun et al. 2005). According to Kevitec et al. (2008), the attachment of AgNPs to the cell membrane surface causes the bacterial effect by interfering with the cell’s permeability and respiration processes.

Although it has been suggested that silver nanoparticles (AgNPs) can penetrate inside bacteria in addition to interacting with their membrane surface (Morones et al. 2005), the effects of AgNP on microorganisms have not yet been thoroughly explored. Researchers feel that the potential of colloidal silver is just beginning to be discovered (Dorjnamjin et al., 2008).

1.2 Nanotechnology

Nanoparticles are viewed as the fundamental building blocks of nanotechnology (Mansoori et al., 2005). Their synthesis is a crucial part of the quickly expanding research efforts in nanoscience and nanoengineering, and they serve as the foundation for the preparation of several nanostructured materials and technologies (Mansoori et al., 2007).

According to nanotechnology, a nanoparticle is a tiny object that exhibits the characteristics and transport of a whole. Nanoparticles can also be called ultrafine particles since their diameters range from 1 to 100 nm.

Fine particles ranging from 100 to 2,500 nm, while coarse particles are ranged between 2,500 and 10,000 nm (Williams, 2008).

A nanometre is one billionth of a metre (10-9 m), which is around the width of three or four atoms. It is a hundred thousand times the breadth of human hair and smaller than the visible light wavelength.

Although materials of many different chemical types can be used to create nanoparticles, metals, metal oxides, silicates, non-oxide ceramics, polymers, organics, carbon, and biomolecules are the most often used materials.

There are many distinct shapes of nanoparticles, including cubes, spheres, cylinders, platelets, tubes, and flowers.

They possess unique physiochemical, optical and biological properties which can be manipulated to suit a desired application. Nanoparticles are of tremendous interest due to their relatively small size, and huge surface to volume ratio.

They exihibit entirely novel features compared to the huge particles of the bulk material and have been included in disciplines of study as diverse as surface science, organic chemistry molecular biology, semi conductive physics, microfabrication, material science, inorganic chemistry and so on.