Antibacterial activity of viologen pendant indole stabilized silver nanoparticles

Synthesis and stabilization of water dispersed silver nanoparticles was achieved by a simple one step procedure using N-methyl-N’-(5-indol-yl-pentyl)-4,4’-bipyridinium dibromide as reducing and stabilizing agent. The viologen pendant stabilized silver nanoparticles were characterized using UV-vis spectroscopy, Transmission Electron Microscope (TEM) and Atomic Force Microscopy (AFM). Further, viologen pendant stabilized silver nanoparticles were studied for antibacterial activity against Staphylococcus aureus, Escherichia coli, Bacillus cereus and Klebsiella nemoniae. 217 Journal of Biopesticides, 2(2): 217221(2009) INTRODUCTION Outbreaks of enterohemorrhagic Escherichia coli infections associated with lettuce and other leaf crops have occurred with increasing frequency in recent years (Islam et al., 2004). Bacillus cereus is associated with rice seed infection in the tropical environment (Cottyn et al., 2001). Food (Portnoy et al., 1976), seed and vegetable (Harmon et al., 1987) contamination were caused by B. cereus. However, it has been used to manage early (Kokalis-Burelle et al., 1992) and late (Zhang et al., 2001) leaf spot disease of peanut using Cercosporidium personatum. Klebsiella pneumoniae is associated with the maize root and also with stem (Chelius and Triplett, 2000). Ingested Klebsiella pneumoniae within adult Mediterranean fruit fly, Ceratitis capitata (Wiedemann) (Diptera: Tephritidae), in a mass rearing facility. This examination revealed the establishment of both bacterial strains as biofilms within the adult intestines, on the apical end of developing and developed eggs and throughout all subsequent life stages (Lauzon et al., 2009). Manduca sexta (Vicki Fleming et al., 2004), Bombyx mori (Kaito et al., 2002), the fruit fly Drosophila melanogaster (Needham et al., 2004) have been used to develop virulence for human pathogens including S. aureus. In nanoscience and technology the fast developing area is the synthesis and study of nanocomposite materials. Metal nanoparticles are of importance due to their potential applications in catalysis, photonics, biomedicine, antimicrobial activity and optics (Wang et al., 2004; Biswas et al., 2004; Shipway and Willner, 2001; Nie and Emory, 1997; Govindaraju et al., 2008; Govindaraju et al., 2009). Size, shape and surface morphology play pivotal roles in controlling the physical, chemical and electronic properties of the nanoscopic materials. The interest arises due to the fascinating aspects of nanoparticles, such as size related electronic magnetic and optical properties. To be more precise polymer metal nanocomposites are promising candidates based on the fact that the very small sized particles enhance the optical properties while the polymer matrix offers flexible functionalities to control host-guest interactions to ensure the growth and distribution of metal nanoparticles (Tamilselvan et al., 1998; Gioco et al., 2004; Pothukuchi et al., 2004). Preparation of metal nanoparticles involves the reduction of metal ions in solutions or in high temperature gaseous environments. Several methods have been reported earlier in relation to the formation of metal nanoparticles on the surface of matrix polymers in hope that the resulting nanocomposites can exhibit synergistic or combinational properties (Chen et al., 2002; Forster and Antonietti, 1998; Chen et al., 1999). Different ways of achieving metal deposition on polymer surfaces and preparing metal clusters or nanoparticles have been reported (Ookoutchaev et al.,1999). Viologen group of compounds finds application in herbicides, anticoccidiostats and other industrial uses due to its physiochemical properties and its non toxic nature. Viologens has been reported for residue analysis, biochemical research and mechanistic studies (Ross and Krieger, 1980). Viologens are also used as sensors in many studies and used for surface grafting in antibacterial studies (Zhilong Shi et al., 2004). In the present work we describe a simple method to prepare highly stabilized silver nanoparticles functionalized viologen pendant indole moieties and their antibacterial activity against B. cereus, E. coli, K. pneumoniae and S. aureus. Synthesis, Silver nanoparticles, Antibacterial activity