The Effects of Single, Janus, and Triple Functionalization of Gold Nanoparticles on Physicochemical Properties and Cellular Uptake

Abstract

Combining direct targeting, enhanced cellular uptake, photothermal transduction capacity, and biocompatibility in the same system is a challenge to make the application of nanoparticles in biomedicine real. This study involves the functionalization of gold nanoparticles (AuNPs) in a few steps with strategic macromolecules to provide characteristics that are key to theragnostic agents. Polyethylene glycol (PEG) is hydrophilic and can improve nanoparticle stability and circulation lifetime. Polylactic acid (PLA) is a biodegradable hydrophobic polymer important to guarantee the interaction and uptake through the cellular membranes. Folate provides specific targeting because tumors usually overexpress folate receptor proteins. Single, double, and triple functionalization of spherical and rodlike AuNPs with these ligands provided different aggregation, stability, and plasmonic properties. Triple functionalization ensured simultaneous nanoparticle stability in an aqueous medium and enhanced cellular uptake. Infrared irradiation increased the temperature of gold nanorods more than of gold nanospheres due to the longitudinal surface plasmon resonance band. The results suggest that this functionalization strategy can be used to tune the desired properties for applications of gold nanoparticles, such as imaging and photothermal therapy in biomedicine research.