Microwave Assisted Synthesis of Silver Nanoparticles using Glucose and Starch

In this study, we have developed a rapid, easy and novel method for the microwave assisted, “green” synthesis of silver nanoparticles (AgNPs) using glucose and starch as the reducing and capping agents, respectively. The properties of AgNPs make them excellent candidates for antibacterial and antitumoral agents, biosensors, supercapacitors and theranostic vehicles amongst others. Different morphologies of the nanoparticles impart them these multifarious applications. Many traditional synthesis routes use toxic chemicals and imprudent amounts of energy and therefore pose a potential hazard to health and the environment. Microwave synthesis of silver nanoparticles is a faster and more energy efficient route. In addition, microwave assisted synthesis can be a robust and efficient platform to synthesize various shape and size-controlled inorganic nanoparticles. We fixed the parameters based on the reproducibility of the experiments, thereby establishing the synthesis methodology. AgNP production was optimized as a function of reaction time, temperature and molar concentrations of the reactants. Focus is laid on the effect of microwave, the amount of time and power required in terms of efficient use of energy, possibility of scale up and process intensification. The size, shape and crystallinity of the AgNPs were characterized by UV–vis spectroscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD) and inductively coupled plasma atomic emission spectroscopy (ICP-AES). We also carried out thermal gravimetric analyses (TGA) to assess the thermal stability of the nanoparticles and to verify the formation of AgNPs. Furthermore, the AgNP yield, energy utilization and reaction mechanism, which has not been well documented in literature, was also proposed. There was a change of less than 2% in the absorbance of the SPR band of the as prepared AgNPs after 2 weeks, thereby validating that the particles were uniform and stable over time.

Keywords: Silver nanoparticles, microwave synthesis, green chemistry