Functionalization of gold nanoparticles by β-cyclodextrin as a probe for the detection of heavy metals in water and photocatalytic degradation of textile dye

Gold nanoparticles (AuNPs) and AuNPs functionalized by beta-cyclodextrin (beta-CD/AuNPs) were prepared successfully through chemical reduction method. The structural, morphological, optical, compositional and vibrational studies for the AuNPs and beta-CD/AuNPs were carried out. Functionalization of AuNPs by beta-CD was confirmed with FT-IR results. The UV-visible absorption spectra exhibit a red-shift with decreasing average particle size. This sustains the enhancement in surface area (SA) to volume (V) ratio that is one of the peculiar characteristics of nanoparticles. TEM results show that beta-CD/AuNPs formed were monodispersed and self assembled. Also it shows a decrease in average particle size and improved distribution. The use of beta-CD in the synthesis of AuNPs are revealed not only create uniform small sized nanoparticles but these water soluble nanoparticles have very good antibacterial action by inhibiting the growth of bacteria commonly found in water and sensing activity for sensing the concentration of toxic metals in water. The sensitivity of the system towards copper (Cu) concentration was found as 1.788/mM for beta-CD/AuNPs and 1.333/mM for AuNPs. The photo- catalytic action of the obtained nanoparticles increases with decreasing average particle size. The K-app value of this photocatalytic degradation of textile dyeing waste water in presence of AuNPs was 0.002/min and beta-CD/ AuNPs was 0.005/min. This is a non-toxic and eco-friendly approach.

Automated summary

The successful synthesis of β-CD/AuNPs with excellent properties was achieved, showing good antibacterial action and metal detection activity, indicating potential applications in water treatment.