Synthesis of β-cyclodextrin functionalized gold nanoparticles for the selective detection of Pb2+ ions from aqueous solution

In the present study we carried out the synthesis of beta-cyclodextrin (beta-CD) functionalized gold nanoparticles (AuNPs) using a microwave assisted heating method in alkaline media. Stable dispersion of beta-CD stabilized AuNPs was obtained at an optimized pH of 10.5. At this pH value the deprotonated secondary hydroxyl group of beta-CD shows the highest chelating affinity toward Pb2+ ions thereby inducing AuNP aggregation. The Pb2+ induced aggregation in beta-CD-AuNP solution is monitored by both colorimetric response and UV-Vis spectroscopy. TEM, DLS and FTIR analyses were carried out to confirm the Pb2+ ion induced aggregation behaviour of beta-CD-AuNPs under alkaline conditions. Furthermore at the experimental pH the response of the beta-CD-AuNP system towards Pb2+ ions is selective when compared with other interfering metal cations.