p-Sulfonatocalix[6]arene-Functionalized Gold Nanoparticles: Applications in Drug Delivery and Bioimaging

Surface-functionalized noble metal nanoparticles with macrocyclic hosts have attracted enormous research interest owing to their applications in drug delivery, catalysis, bioimaging, etc. Stable p-sulfonatocalix[6]arene-functionalized gold nanoparticles (SCx6AuNPs) of the sizes ∼7.5 nm have been synthesized and characterized by using UV–vis absorption, transmission electron microscopy, and surface-enhanced Raman spectroscopy measurements. The efficient uptake and stimuli-responsive release of doxorubicin (Dox), an anticancer drug, by the SCx6AuNPs have been established for targeted drug delivery application. The decreased cytotoxicity of Dox loaded on SCx6AuNPs, especially toward normal cell lines, and its multistimuli responsive release validated in both cancerous (A549) and normal (W126) cell lines find promising for selectively targeted drug delivery applications toward cancer cells. At the cellular level, this study also establishes the efficient uptake of the SCx6AuNP nanoconjugates, and its validation has been done by bioimaging measurement by using thioflavin T (ThT) dye loaded on to SCx6AuNPs instead of Dox as the fluorescent tracking probe. The bright fluorescence microscopic image of ThT-SCx6AuNP-stained cancerous cell lines corroborates the uptake of SCx6AuNPs by the cell lines and its projected utility for drug delivery and bioimaging applications.