Water soluble gold nanoparticles based high relaxivity MRI contrast agents

Abstract

Magnetic resonance imaging (MRI) is one of the modern diagnostic techniques that are being used for differentiating between normal and abnormal tissues. The sensitivity of MRI can be enhanced by the use of contrast agents. In this article, the synthesis and characterisation of new derivatives of gold nanoparticles for applications as MRI contrast agents is reported. Gold nanoparticles stabilised by dimethylaminopyridine (DMAP) molecules were prepared by reduction method. These nanoparticles were characterised by UV-visible spectroscopy, transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The presence of surface plasmon band at 525–530 nm in UV-visible spectra confirmed the formation of stable gold nanoparticles. Similarly, the TEM images showed the well dispersed spherical gold nanoparticles. The average diameter of AuNPs as calculated from TEM image analysis was found 2.25 nm. The DMAP molecules were then replaced by Gd-DTPA chelates along with butanethiol molecules. The butanethiol molecules are responsible for restricted tumbling of Gd-DTPA chelates that resulted in the 38% increase in relaxivity of gold nanoparticles based MRI contrast agents.