Parallel multi-parameter study of PEI-functionalized gold nanoparticle synthesis for bio- medical applications: Part 2. Elucidating the role of surface chemistry and polymer structure on performance
Tae Joon Cho, Justin M. Gorham, John M. Pettibone, Jingyu Liu, Jiaojie Tan, Vincent A. Hackley
Despite the breadth and quality of published work in this area, it remains unclear how the specific properties of polyethyleneimine (PEI) and the methods utilized to conjugate it to gold nanoparticles (AuNPs) impact the final product morphology and stability (which presumably impact performance). Recently, we reported a robust, reproducible method for synthesizing PEI functionalized AuNPs (Au- PEIs), which affords the opportunity to investigate structure-function relationships and to further interrogate the correlation between product properties and synthesis. In the current study, the properties of Au-PEIs prepared by the optimized reduction of HAuCl4 using four different structural variants of PEI changed significantly with molar mass and backbone form (branched or linear). In the present study, properties such as size distribution, surface plasmon resonance, morphological state, surface functionality, and shelf-life have been systematically evaluated using dynamic light scattering, UV-Vis absorbance, transmission electron microscopy, inductively coupled plasma mass spectrometry, electrospray-differential mobility analysis, X-ray photoelectron spectroscopy, and attenuated total reflectance FT-IR. This comprehensive analysis provides insight into the surface chemistry and reactive groups involved in conjugation, as a function of conjugate size and morphology, and relates these results to the observed colloidal stability of the product in relevant media, including exposure to physiological variables such as salt, pH, proteins, and thermal changes. Overall, this work advances progress toward intelligent design of engineered nanoscale drug delivery systems and devices.