Abstract
Nano-sized metal particles are attracting much interest in industrial and biomedical applications due to the recent progress and development of nanotechnology, and the surface-modifications by appropriate polymers are key techniques to stably express their characteristics. Herein, we applied cyclic poly(ethylene glycol) (c-PEG), having no chemical inhomogeneity, to provide a polymer topology-dependent stabilization for the surface-modification of gold nanoparticles (AuNPs) through physisorption. By simply mixing c-PEG, but not linear counterparts, enables AuNPs to maintain dispersibility through freezing, lyophilization, or heating. Surprisingly, c-PEG endowed AuNPs with even better dispersion stability than thiolated PEG (HS–PEG–OMe). The stronger affinity of c-PEG was confirmed by DLS, ζ-potential, and FT-IR. Furthermore, the c-PEG system exhibited prolonged blood circulation and enhanced tumor accumulation in mice. Our data suggests that c-PEG induces physisorption on AuNPs, supplying sufficient stability toward bio-medical applications, and would be an alternative approach to the gold–sulfur chemisorption.
Highlights
Nano-sized metal particles are attracting much interest in industrial and biomedical applications due to the recent progress and development of nanotechnology, and the surfacemodifications by appropriate polymers are key techniques to stably express their characteristics
We reported that micelles composed of cyclized poly(ethylene glycol) (PEG)-containing amphiphilic block copolymers feature a higher tolerance towards temperature and salinity compared to their linear counterparts in an aqueous solution, which was proven by turbidity tests and dynamic light scattering[20,21,22]
PEG was cyclized via etherification, forming cyclic PEG (c-PEG) without inhomogeneity in the chemical structure, by using the modified tosylation method according to previous reports (Fig. 1a)[26,27]
Summary
Nano-sized metal particles are attracting much interest in industrial and biomedical applications due to the recent progress and development of nanotechnology, and the surfacemodifications by appropriate polymers are key techniques to stably express their characteristics. Metal nanoparticles are used in a wide range of applications which include optics[1], sensors[2], biomedicine[3], electronics[4], and catalysis[5] Metal nanoparticles such as gold, silver, and copper nanoparticles exhibit surface plasmon resonances (SPR) as a result of their interaction with light which manifests itself in the different colors of the corresponding colloidal solutions depending on the particle size and shape[6]. The use of PEG as a polymeric stabilizer of AuNPs, where the effects of the polymer topology (linear vs cyclic) as well as the end groups (–OH vs –OMe vs –SH) against freezing, lyophilization, heating, and a physiological condition, is investigated with the above observations in mind (Supplementary Fig. 1). We find that c-PEG endows AuNPs with enhanced dispersion stability
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