How PEO-PPO-PEO Triblock Polymer Micelles Control the Synthesis of Gold Nanoparticles: Temperature and Hydrophobic Effects

Abstract

Aqueous micellar solutions of F68 (PEO(78)-PPO(30)-PEO(78)) and P103 (PEO(17)-PPO(60)-PEO(17)) triblock polymers were used to synthesize gold (Au) nanoparticles (NPs) at different temperatures. All reactions were monitored with respect to reaction time and temperature by using UV-visible studies to understand the growth kinetics of NPs and the influence of different micellar states on the synthesis of NPs. The shape, size, and locations of NPs in the micellar assemblies were determined with the help of TEM, SEM, and EDS analyses. The results explained that all reactions were carried out with the PEO-PPO-PEO micellar surface cavities present at the micelle-solution interface and were precisely controlled by the micellar assemblies. Marked differences were detected when predominantly hydrophilic F68 and hydrophobic P103 micelles were employed to conduct the reactions. The UV-visible results demonstrated that the reduction of gold ions into nucleating centers was channeled through the ligand-metal charge-transfer complex (LMCT) and carried out by the surface cavities. Excessive hydration of the surface cavities in the case of F68 micelles produced a few small NPs, but their yield and size increased as the micelles were dehydrated under the effect of increasing temperature. The results concluded that the presence of well-defined predominantly hydrophobic micelles with a compact micelle-solution interfacial arrangement of surface cavities ultimately controlled the reaction.

Targeted polyethylene glycol gold nanoparticles for the treatment of pancreatic cancer: from synthesis to proof-of-concept in vitro studies

“…25,85 Applying the successful concept used for producing Aurimune 9 as template for designing our gold nanocarrier, the size of PEG-AuNPs was engineered to obtain a delivery platform with an organic/inorganic core bigger than 8 nm (Figure 6D), thus avoiding rapid clearance from the kidneys following intravenous administration. 86 A PEG layer was also introduced to 1) prolong the nanocarrier circulation time, 2) avoid the reticulo-endothelial system clearance, 75 and 3) enhance the absorption and clearance of AuNPs when administered through intravenous injection.…”

Template Synthesis of Subnanometer Gold Clusters in Interfacially Cross-Linked Reverse Micelles Mediated by Confined Counterions

“…Because mixing uncross-linked 1 and HAuCl 4 yielded the ligand-exchanged product (i.e., AuBr 4 − ) instead of gold clusters, the stability of AuBr 4 − must be quite different in the un-cross-linked RMs and in the ICRMs. In the literature, when dehydrated within block copolymer micelles 28 or encapsulated within dendrimers, aurate was reported to be reduced by otherwise unlikely functional groups such as poly(ethylene glycol). 29 Although the ICRM core contains a nanosized water pool, the entrapped aurate is not expected to be fully solvated as in aqueous solution.…”

Vesicle formation in mixture of a PEO-PPO-PEO block copolymer (Pluronic P123) and a nonionic surfactant (Span 65) in water

“…Poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) block copolymers, which are commercial available amphiphilic polymers as Pluronic and Poloxemer, are widely used as dispersion stabilizers [1,2], pharmaceutical ingredients [3][4][5], biomedical materials [6,7] and templates for the synthesis of mesoporous materials [8][9][10][11] and nanoparticles [12][13][14][15][16][17][18][19]. This is due to a variety of PEO-PPO-PEO block copolymer self-assemblies tuned by molecular characteristics, concentration and temperature in the presence of selective solvents such as water [20,21].…”