Eggshell membrane: a natural biotemplate to synthesize fluorescent gold nanoparticles

In this article we report a simple, environmentally friendly, and naturally available protein based biotemplate, viz. the chicken eggshell membrane, truly one of nature's gifts, for preparing highly fluorescent gold nanoparticles in solution at ambient conditions in a single step. We propose this as a simple green method to prepare gold nanoparticles both in solution and on the membrane for various applications. A stable colloidal solution of fluorescent Au nanoparticles has been formed in situ during the reduction. The gold nanoparticles, consisting of sizes below 20 nm, were highly fluorescent and exhibited intense blue emission around 437 +/- 5 nm. Red emission around 630 +/- 5 nm was also observed for the solution. The novelty of this technique lies in the unique properties of this membrane, such as high resistance to pH, safety in handling, and abundant availability in nature. The most important feature of this method is the easy abundance of the source material, which enables cost-effective preparation of gold nanoparticles. In addition to preparing nanoparticles of metals for various applications, this could be used as a very simple method to recover precious metals from chemical and industrial waste.