PHYS01200704032 Debes Ray - Homi Bhabha National Institute

Chapter 1: Synthesis, Characterization and Applications of Gold Nanoparticles
Figure 1.1. The length scale of interest in nanoscience (1–100 nm) and its comparison with
smaller (atomic) and larger (macroscopic) structures.
Many nano forms of matter exist around us and their historical milestones spans over
centuries. One of the earliest nano-sized objects known to us was made of gold. Faraday
prepared colloidal gold in 1856 and called the particles he made the „divided state of gold‟
which can be suspended in water [10]. In 1890, the German bacteriologist Robert Koch found
that compounds made with gold inhibited the growth of bacteria and for this he was awarded
Nobel Prize for medicine in 1905. The use of gold in medicinal preparations is not new. In
the Indian medical system called Ayurveda, gold is used in several preparations. One popular
preparation is called „Saraswatharishtam‟, prescribed for memory enhancement. All these
preparations use finely ground gold. The metal was also used for medical purposes in ancient
Egypt where the Egyptians used gold in dentistry [11]. Colloidal gold had been incorporated
in glasses and vases to give them colour [12]. The oldest of these is the 4 th Century AD
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