Binding of Nanoparticles to Aminated Plasma Polymer Surfaces is Controlled by Primary Amine Density and Solution pH

Surface nanoengineering is a valuable tool to create materials with sophisticated properties required to address unmet needs in fields such as medicine, biology or energy. This study examines the dependence of nanoparticle immobilization as a function of surface amine group density. The concentration of surface amine groups was tuned using gradients deposited from the plasma phase of allylamine and octadiene (pp-AA/OD) precursors mixtures. Silver nanoparticles capped with carboxylic acid groups (COOH-AgNPs) were used to interrogate the effect of primary amine (-NH₂) surface density on nanoparticle's electrostatic immobilization onto freshly made and aged plasma polymer films. An increase in amine group density could be correlated with greater number of functionalized silver nanoparticles bound to the surface. In addition, the pp-AA/OD surface charge and nanoparticle binding density could be controlled via pH of the AgNPs colloidal solution. The results suggest that pp-AA/OD plasma polymer films are suitable platforms for implementing advanced nanoengineered materials that could be used in many advanced applications, ranging from medicine to sensing and electronics.