Size Control and Enhanced Stability of Silver Nanoparticles by Cyclic Poly(ethylene glycol)

Abstract

Silver nanoparticles (AgNPs) are used in a wide range of applications, and the size control and stability of the nanoparticles are crucial aspects in their applications. In the present study, cyclized poly(ethylene glycol) (c-PEG) with various molecular weights, along with linear PEG with hydroxy chain ends (HO–PEG–OH) and methoxy chain ends (MeO–PEG–OMe) were applied for the Tollens’ synthesis of AgNPs. The particle size was significantly affected by the topology and end groups of PEG. For example, the size determined by TEM was 40 ± 7 nm for HO–PEG5k–OH, 21 ± 4 nm for c-PEG5k, and 48 ± 9 nm for MeO–PEG5k–OMe when the molar ratio of PEG to AgNO3 (ω) was 44. The stability of AgNPs was also drastically improved by cyclization; the relative UV–Vis absorption intensity (A/A0 × 100%) at λmax to determine the proportion of persisting AgNPs in an aqueous NaCl solution (37.5 mM) was 58% for HO–PEG5k–OH, 80% for c-PEG5k, and 40% for MeO–PEG5k–OMe, despite the fact that AgNPs with c-PEG5k were much smaller than those with HO–PEG5k–OH and MeO–PEG5k–OMe.

Application of Polymer Brush-Shells on Nanoparticles for Controlling Interaction with Serum

“…The cPEG-Ag NPs exhibited lower and more uniform particle size. 104 On gold NPs, cPEG brushes formed a thicker layer than the linear counterparts, resulting in enhanced stabilization even when the NPs were frozen, lyophilized, and heated. 105 Our group demonstrated that cyclic PAOXAs can form ultra-dense shells that protect NP cores from interacting with proteins.…”

Polymer Brushes on Nanoparticles for Controlling the Interaction with Protein-Rich Physiological Media

“…The cPEG-Ag NPs exhibited a lower and more uniform particle size. 108 On gold NPs, cPEG brushes formed a thicker layer than the linear counterparts, resulting in enhanced stabilization even when the NPs were frozen, lyophilized, and heated. 109 Our group demonstrated that cyclic PAOXAs can form ultradense shells that protect NP cores from interacting with proteins.…”

“…To highlight the effect of polymer topology on the properties of core–shell systems, silver NPs were functionalized with cyclic PEG ( c PEG) and compared to Ag NPs functionalized with linear PEG chains terminated with either hydroxyl or methoxy groups. The c PEG-Ag NPs exhibited a lower and more uniform particle size . On gold NPs, c PEG brushes formed a thicker layer than the linear counterparts, resulting in enhanced stabilization even when the NPs were frozen, lyophilized, and heated …”

Antiviral Activity of Ag5IO6, a Unique Silver Compound

“…Self-limited-remains active in the presence of chloride ions, proteins, etc. [8,16] Released active species (Ag + ) react with components to form insoluble compounds [4] Released active species react with components to form insoluble compounds [4] Stability Good stability under a number of conditions (light, heat, solvents, and sterilization) [16] Stability issues (capping often required) [20,21] Varies with compound, often poor (e.g., not light stable, challenges with sterilization)…”