Nanocrystalline p-hydroxyacetanilide (paracetamol) and gold core–shell structure as a model drug deliverable organic–inorganic hybrid nanostructure

Abstract

We report on the generation of core–shell nanoparticles (NPs) having an organic nanocrystal (NC) core coated with an inorganic metallic shell, being dispersed in aqueous medium. First, NCs of p-hydroxyacetanilide (pHA)—known also as paracetamol—were generated in an aqueous medium. Transmission electron microscopy (TEM) and powder X-ray diffraction (XRD) evidenced the formation of pHA NCs and of their crystalline nature. The NCs were then coated with Au to form pHA@Au core–shell NPs, where the thickness of the Au shell was on the order of nanometers. The formation of Au nanoshell—surrounding pHA NC—was confirmed from its surface plasmon resonance (SPR) band in the UV/Vis spectrum and by TEM measurements. Further, on treatment of the core–shell particles with a solution comprising NaCl and HCl (pH < 3), the Au shell could be dissolved, subsequently releasing pHA molecules. The dissolution of Au shell was marked by a gradual diminishing of its SPR band, while the release of pHA molecules in the solution was confirmed from TEM and FTIR studies. The findings suggest that the core–shell NP could be hypothesized to be a model for encapsulating drug molecules, in their crystalline forms, for slow as well as targeted release.