title: Role of thiol-containing polyethylene glycol (thiol-PEG) in the modification process of gold nanoparticles (AuNPs): stabilizer or coagulant?
abstract: Gold nanoparticles (AuNPs) have significant potential as biosensors and drug delivery vehicles, as well as imaging and thermotherapy agents. Thiol-containing polyethylene glycol (PEG), hereafter denoted as thiol-PEG, is widely used as a macromolecular ligand for modifying AuNPs and stabilizing them under various environments. In this work, a series of thiol-PEG-modified AuNPs (PEGylated AuNPs) with different PEG molecular weights (Mw) were synthesized. The saturated capping density, charge-screening ability, and stability of the PEGylated AuNPs were then examined. The results showed that high-Mw PEG stabilized the AuNPs and screened the surface charge better than low-Mw PEG, but the latter showed higher saturated capping density. More importantly, PEG exhibited the maximum coagulation concentration (MCC) and critical stabilization concentration (CSC) in the stabilizing process of the AuNPs. Thiol-PEG acted as an AuNP stabilizer only when its concentration was higher than the CSC. Otherwise, thiol-PEG accelerated AuNPs aggregation, which reached the peak level at the MCC. These results were significant in recognizing the influence of thiol-PEG on the stability of AuNPs.
authors.affiliation: Key Laboratory of Functional Polymer Materials, Ministry of Education, Institute of Polymer Chemistry, Nankai University, Tianjin 300071, PR China. duruo@nankai.edu.cn
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Qin-Qin
authors.initials: QQ
authors.lastname: Wei
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
authors.forename: Bi-Cui
authors.initials: BC
authors.lastname: Wang
authors.forename: Sai-Hui
authors.initials: SH
authors.lastname: Zhang
authors.forename: Zhi
authors.initials: Z
authors.lastname: Yuan
mesh_terms: D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D011092:Polyethylene Glycols / Q000737:chemistry*; D013438:Sulfhydryl Compounds / Q000737:chemistry*
chemical_list: D013438:Sulfhydryl Compounds; D011092:Polyethylene Glycols; D006046:Gold