Facile Synthesis and X-ray Attenuation Properties of Ultrasmall Platinum Nanoparticles Grafted with Three Types of Hydrophilic Polymers

Ultrasmall platinum nanoparticles (Pt-NPs) grafted with three types of hydrophilic and biocompatible polymers, i.e., poly(acrylic acid), poly(acrylic acid-co-maleic acid), and poly(methyl vinyl ether-alt-maleic acid) were synthesized using a one-pot polyol method. Their physicochemical and X-ray attenuation properties were characterized. All polymer-coated Pt-NPs had an average particle diameter (d(avg)) of 2.0 nm. Polymers grafted onto Pt-NP surfaces exhibited excellent colloidal stability (i.e., no precipitation after synthesis for >1.5 years) and low cellular toxicity. The X-ray attenuation power of the polymer-coated Pt-NPs in aqueous media was stronger than that of the commercial iodine contrast agent Ultravist at the same atomic concentration and considerably stronger at the same number density, confirming their potential as computed tomography contrast agents.