We report a microwave-mediated simple and rapid method of gold nanoparticles (GNPs) synthesis using latex of Calotropis procera. UV-Vis spectroscopic studies indicated the formation of GNPs. The GNPs were stable at room temperature (25°C) for six months. Transmission electron microscope (TEM) micrographs of the synthesized GNPs showed the formation of spherical nanoparticles with an average size of 13 ± 5？nm. SAED and XRD confirmed the crystalline nature of GNPs. Fourier transform infrared (FTIR) analysis indicated the presence of organic coating on the nanoparticles. Cytotoxicity of the GNPs was tested on HeLa and A549 and found to be nontoxic which was indicating that latex of Calotropis procera provided the nontoxic coating on GNPs, thus can be used as biomedical and pharmacological applications. 1. Introduction Gold nanoparticles (GNPs) have been of immense interest for their unique chemical and physical properties and potential technological applications in various fields ranging from catalysis to disease diagnosis [1–15]. Conventional methods of GNPs synthesis mostly rely on the use of synthetic chemicals and prolonged heating [16–19]. Owing to the increased awareness for potential toxicity of GNPs associated with biological applications, alternative methodologies for biocompatible GNPs synthesis are gaining importance. Replacement of toxic chemicals as a reducing and stabilizing agent is the prime concern of this new approach. Reports about the successful synthesis and subsequent stability of GNPs by using different biomaterials sourced from plant and microbes are now increasing day by day [20–27]. On the other hand, microwave (MW) dielectric heating is a fast emerging and widely accepted new processing technology for a variety of inorganic synthesis and biomedical applications [28–33]. Compared to the conventional heating, MW irradiation shortens reaction times and improve yield without causing any appreciable alteration in the composition of products of a chemical reaction. In contrast to general heating treatment, MW synthesis favors homogeneous heating through the entire bulk of the reaction mixture in a container, leading to a more homogeneous and easy nucleation of noble metal nanoparticles [34–37]. We found that latex of the plant C. procera, a multifarious plant having many remedial properties, can act as both reducing and capping agent in the GNPs synthesis through conventional heating [38]. This motivated us to further explore the synthesis of GNPs through MW irradiation. We found remarkable shortening in the reaction time and GNPs of
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