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Gold nanoparticles (AuNPs) provide unique nanoplatform for a variety of applications as in computed tomography (CT), photoacoustics, plasmonic photothermal and photodynamic therapies, and magnetic resonance imaging (MRI) [54]. The AuNPs are available as nanospheres, nanorods, nanocages, nanoshells, and nanostars on large scale. These nanoparticles can be even prepared via green synthesis methods on large scale using extracts of neem leaves [55], Hibiscus rosa sinensis [56], Ocimum tenuiflorum, Azadirachta indica, Mentha spicata leaves, Citrus sinensis [57], Maduca longifolia [58], and Abelmoschus esculentus peel [59]. The antioxidants present in the extracts act as reducing agent for the metal salts, leading to the growth and stabilization of the NPs [60]. The optical characteristics of AuNPs are dependent on their shape and size. AuNPs can enhance scattering of light up to five to six times in comparison to most strongly absorbing organic dyes [61]. AuNPs of larger size undergo scattering and absorption in a similar fashion, and hence, this property of AuNPs can be used for bioimaging [62]. Composition of the nanoparticles also affects their optical properties. Wavelength of surface plasmon resonance (SPR) [63], which determines the specific frequency at which amplitude of oscillation reaches its maxima, changes on incorporation of silica [64].