The “Needle in the Haystack” Makes the Difference: Linear and Hyperbranched Polyglycerols with a Single Catechol Moiety for Metal Oxide Nanoparticle Coating

Abstract

Multifunctional linear (CA-linPG) and hyperbranched polyglycerols (CA-hbPG) bearing a single catechol unit were synthesized by use of an acetonide-protected catechol initiator for the anionic polymerization of ethoxyethyl glycidyl ether (EEGE) and glycidol, respectively. A key feature for the synthesis of the hyperbranched structures was a selective, partial acetal deprotection step. The single catechol unit among a large number of aliphatic 1,2-and 1,3-diol moieties (i.e., the "needle in the haystack") in both linear and hyperbranched polyglycerols permits dispersion of transition metal oxide nanoparticles in brine, as demonstrated for manganese oxide (MnO) nanoparticles. Molecular weights of the single catechol bearing PGs ranged from 950 to 2350 g•mol −1 for CA-linPG and from 3750 to 5750 g•mol −1 for CA-hbPG with narrow and monomodal molecular weight distributions (M w /M n < 1.23 for linPG and M w /M n = 1.22−1.48 for hbPG). Both C-linPGs and C-hbPGs are suitable hydrophilic capping agents to generate highly hydroxyl-functional nanoparticles with hydrophilic PG shell. The PG content of the polymer-coated MnO nanoparticles (diameter 17 nm) was in the range 21−54 wt %, as determined via TGA. The MnO nanoparticles with a hydrophilic, multifunctional polyglycerol shell may represent a promising alternative to iron oxide or gadolinium contrast agents for MRI.

Aliphatic Polyethers: Classical Polymers for the 21st Century

“…Using “graft on graft” strategies with repeating cycles of deprotonation, polymerization, and acidic deprotection, highly branched polymers with high molecular weights ( M n > 1 800 000 g mol −1 ) have been reported . Since then, different functional initiators as well as termination agents were applied for the preparation of well‐defined polymers with exactly one functional moiety at the chain end …”

Polyamidoamine and polyglycerol; their linear, dendritic and linear–dendritic architectures as anticancer drug delivery systems

“…Recently, hyperbranched polyglycerols have been used frequently to coat the surfaces of various nanomaterials including magnetic Fe 3 O 4 nanoparticles, 237 carbon nanotubes, 238 graphene oxide sheets, 239 fluorescent nanodiamond, 240 manganese oxide nanoparticles, 241 fluorescent silicon nanoparticles 242 and upconversion nanoparticles (NaYF 4 :Yb/Er), 243 in order to be used in biomedical applications such as drug delivery, bioimaging probes and MRI contrast agents. Hybrid nanomaterials containing nanoparticles and HPG are synthesized via different approaches, including ''grafting-from'', 244 ''grafting-to'', 245 and noncovalent interactions.…”

Hyperbranched Poly(ester‐enamine) from Spontaneous Amino‐yne Click Reaction for Stabilization of Gold Nanoparticle Catalysts

“…In the meanwhile, multi-functional HPBs can be functional as templates to control the size, stability, and solubility of metal nanoparticles (metal NPs). [31][32][33][34][35][36] For the most part, HBPs-encapsulated metal NPs are prepared by sequestering metal ions within HBPs followed by chemical reduction to yield metal NPs. The particle size of metal NPs depends on the number of metal ions initially loaded into HBPs.…”