One-pot synthesis of pH and temperature sensitive gold clusters mediated by a recombinant elastin-like polymer

Here, we described a "one-pot" synthesis of smart hybrid materials based on elastin-like recombinamers (ELRs) and gold nanoparticles. Outstandingly, the reduction of auric acid in the presence of ELR G1u15 gave biohybrid Au-Glu15. TEM analysis carried out for Au-Glu15 exhibited nano-sized gold crystals with diameter ranging from 2 to 11 nm. Furthermore, Au-Glu15 promoted the formation of linear arrangements of gold clusters in areas of low particle density. Remarkable was that analogous architectures were obtained in a control experiment carried out with Glu15 and gold nanoparticles synthesized via a citrate reduction route. Therefore, Glu15 promoted the formation of 2D linear arrangements of gold clusters that exhibited interparticle distances in the range from 10 to 40 nm. Notable were the branched nanostructures exhibited by Au-Glu15B obtained for reduced gold-ELR mixtures that exhibited a lower gold ratio. On the other hand, Au-Glu15 exhibited spectroscopic properties (UV-vis absorption) that could be modulated as function of pH and temperature of the environment as result of reversible aggregation-expansion of gold nanoparticles. Thereby, Au-Glu15 displayed remarkable features suitable for the development of stimuli responsive optical sensors and detectors for biological applications that could operate in aqueous media and under a wide range of pH's. (C) 2010 Elsevier Ltd. All rights reserved.