ANTIBACTERIAL EVALUATION OF AFANG LEAF EXTRACT AND ITS SYNTHESIZED SILVER NANOPARTICLES. A RESEARCH PROJECT MATERIAL ON BIOCHEMISTRY
INTRODUCTION AND LITERATURE REVIEW
Nanoscience has been the subject of substantial research in recent years. It has been explored by researchers in various fields of science and technology (Kholoud et al. 2010). The novel properties of NPs have been exploited in a wide range of potential applications such as in medicine, cosmetics, renewable energies, environmental remediation, biomedical devices (Quang Huy, 2013), electronics, optics, organic catalysis, vector control, sensor, etc., have drawn extensive attention to this field of study (Mousavand et al. 2007). Among the metals, silver nanoparticles have shown potential applications in various fields such as the environment, bio-medicine, catalysis, optics and electronics (Rao et al., 2000). Silver nanoparticles are mostly smaller than 100 nm and consist about 20–15,000 silver atoms. In its nanoscale form, silver exhibits unique physicochemical and biological activities. This has made them useful as sensor, vector control, antimicrobial, anticancer, and antiplasmodial agents, catalysts, among others (Elemike et al. 2014; Vinod et al. 2014; Kathiravan et al. 2014; Saraschandra and Sivakumar 2014; Namita and Soam 2014).
Concerted effort has been made to synthesize diverse range of silver nanoparticles varying in size, geometry, and morphology because of their potential applications, particularly 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). The size, geometry, dispersion and stability often determine the suitability of the nanoparticles for certain applications. Synthesis may involve physical means such as ultraviolet light, microwaves, photo-reduction, or chemical reduction using hydrazine, ascorbic acid, sodium borohydride, glucose, and organic stabilizers or biological means using plant extract, microorganism or plant sap. Several physical and chemical methods have been used to synthesize and stabilize silver nanoparticles (Senapati et al., 2005, Klaus-Joerger et al., 2001). The most popular chemical approaches, including chemical reduction using a variety of organic and inorganic reducing agents, electrochemical techniques, physicochemical reduction, and radiolysis are widely used for the synthesis of nanoparticles.
Although these means are fast and easy, they are either expensive or toxic particularly the chemical method and may lead to non eco-friendly byproducts thus the need for environmental, nontoxic synthetic protocols for nanoparticles synthesis. In the global efforts to reduce generated hazardous waste,