Rahul KUMAR, Simona BADILESCU, Muthukumaran PACKIRISAMY; Sonochemical Stabilization of Gold Nanostars: Effect of Sonication Frequency on the Size, Shape and Stability of Gold Nanostars; Advanced Nano-Bio-Materials and Devices; 2017:1(4):172-181

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In this work, the effect of sonication on the size, morphology, and stability of gold nanostars was investigated for the first time. It was found that the seed-mediated method, followed by the sonication treatment developed in this study, offers new opportunities to synthesize aqueous suspensions of monodispersed gold nanostars with prolonged stability. The results indicate that at a sonication frequency of 25 kHz, the maximum average nanostar size of 120nm is attained. Increasing the sonication frequency, the average size of nanostars decreased significantly and, consequently, the position of the Localized Surface Plasmon Resonance (LSPR) band, could be easily tuned. It is thought that the change in the morphology is due to the collapse of the cavitation bubble which generates extreme conditions of pressure and temperature. Cavitation images in the gold nanostars solution were for the first time extracted by using an original software. It is found that the gold nanostars, after ultrasound treatment, are substantially more stable because their aggregation becomes much slower. The use of the sonication technique to stabilize gold nanostars, without any additional chemical stabilizer, is both technologically and scientifically important. It can be expected that by using this technique, to be able to produce large volumes of consistent quality, stable gold nanostars.