ABSTRACT
Although physical and chemical procedures such as ultraviolet (UV) irradiation, microwave treatment, aerosol treatment, laser ablation, ultrasonic elds and photochemical reduction form the primary route of synthesis of nanoparticles, their high expense and the release of toxic and hazardous by-products restrict their use in the eld of biomedical sciences. Hence, researchers in the eld of material sciences and bionanosciences turned their attention towards biological approaches. Moreover, biological methods are safe, cost-effective, sustainable and eco-friendly which results in better control over size, production, shape and crystallinity. Various biophysical and optical techniques such as UV-Vis spectroscopy, x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are commonly employed to characterise both inorganic and organic nanoparticles. UV-Vis spectroscopy forms the basic and primary mode of the detection of nanoparticles, whose wavelength lies between 300 and 800 nm (Feldheim and Foss 2002). The absorbance measurements in the wavelength ranges of 400-450 nm and 500-550 nm are typical for silver and gold nanoparticles, respectively (Huang and Yang 2004; Shankar et al. 2004). SEM and TEM give possible information regarding the size and shape of the nanoparticles produced (Schaffer et al. 2009). FT-IR spectroscopy helps in identifying the possible functional groups present on the surface of the nanoparticle and the crystalline nature of the material was conrmed from XRD (Chithrani et al. 2006). This chapter describes the recent developments made towards the biological approaches on the synthesis of nanomaterials.
