Synthesis and Characterization of Gold/Copper@Polydopamine Nanocomposite for a Dual Modal CT-MRI Medical Imaging

Background: The clinical potential of dual modal contrast-enhancement materials (CEM) for CT-MRI is significant regarding the ability to visually detect, with higher sensitivity and specificity, changes in soft tissues or tumors. The combination of both imaging modalities may yield synergetic information, resulting in a more conclusive diagnosis. In aim to generate contrast-enhanced images by two different physical phenomena using a single CEM administration, a formulation of bimetallic nanocomposite consisting of gold and copper, was designed and studied.

Methods: A new procedure was developed by employing simple wet-chemical synthesis utilizing the unique properties of polydopamine for co-reduction of HAuCl4 and CuO nanoparticles. Various analytical techniques were applied to characterize Au/Cu@polydopamine nanocomposite in terms of size, morphology, and composition, including measurements of high-resolution transmission electron microscopy (HR-TEM), X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and inductively coupled plasma mass spectrometry (ICP-MS). The oxidation states of copper were determined by X-ray photoelectron spectroscopy (XPS) and electron energy loss spectroscopy (EELS). In vitro cytotoxicity test using mammalian cell line was determined by MTT assay. Longitudinal magnetic relaxation and X-ray attenuation properties were assessed by phantom experiments and an ex vivo poultry heart model.

Results: The analysis revealed nanocomposite made by polydopamine matrix embedded with Au nanoparticles and Cu species. The nanocomposite with Au:Cu atomic ratio of 84:16 provided a visual enhancement in both CT and MR imaging.

Conclusion: Our findings show that Au/Cu@polydopamine nanocomposite represents a promising candidate for further clinical development as a new generation of CT-MRI dual-modal imaging contrast agent.