Branched Polyhedral Oligomeric Silsesquioxane Nanoparticles Prepared via Strain-Promoted 1,3-Dipolar Cycloadditions

Abstract

Conjugation of small organic molecules and polymers to polyhedral oligosilsesquioxane (POSS) cores results in novel hybrid materials with unique physical characteristics. We report here an approach in which star-shaped organic–inorganic scaffolds bearing eight cyclooctyne moieties can be rapidly functionalized via strain-promoted azide–alkyne cycloaddition (SPAAC) to synthesize a series of nearly monodisperse branched core–shell nanoparticles with hydrophobic POSS cores and hydrophilic arms. We established that SPAAC is a robust method for POSS core octafunctionalization with the reaction rate constant of 1.9 × 10−2 M−1 s−1. Functionalization with poly(ethylene glycol) (PEG) azide, fluorescein azide, and unprotected lactose azide gave conjugates which represent different classes of compounds: polymer conjugates, fluorescent dots, and bioconjugates. These resulting hybrid compounds were preliminarily tested for their ability to self-assemble in solution and at the air–water interface. We observed the formation of robust smooth Langmuir monolayers with diverse morphologies. We found that polar lactose moieties are completely submerged into the subphase whereas the relatively hydrophobic fluorescein arms had extended conformation at the interface, and PEG arms were partially submerged. Finally, we observed the formation of stable micelles with sizes between 70 and 160 nm in aqueous solutions with size and morphology of the structures dependent on the molecular weight and the type of the peripheral hydrophilic moieties.

Biodegradable Inorganic–Organic POSS–PEG Hybrid Hydrogels as Scaffolds for Tissue Engineering

“…The formation of POSS aggregates was probably due to the absence of chemical binding forces and the formation of intermolecular hydrogen bonds of the hydroxyl groups between the POSS molecules. In addition, a core‐shell structure, which is formed by the self‐assembly behavior of the copolymer, can be clearly seen in the figures . The hydrophobic POSS formed the core of the micelles, while the hydrophilic PEG formed the shell.…”

“…In addition, a core-shell structure, which is formed by the self-assembly behavior of the copolymer, can be clearly seen in the figures. [28][29][30] The hydrophobic POSS formed the core of the micelles, while the hydrophilic PEG formed the shell. Moreover, because of the special core-shell structure, hydrophobic POSS is wrapped in the hydrophilic PEG outer layer, which improves the solubility of the polymer and POSS particles can be dispersed in the material evenly.…”

“Shine & Click” Photo‐Induced Interfacial Unmasking of Strained Alkynes on Small Water‐Soluble Gold Nanoparticles

“…[13][14][15][16] More recently,T sukruk and co-workers prepared branched polyhedral oligomeric silsesquioxane nanoparticles by the interfacial SPAAC reaction. [17] Yi and co-workers reportedc hitosan-poly(ethylene glycol) microparticles featuring azadibenzocyclooctynes (ADIBO) and their potential to undergo bioconjugation in the SPAAC reactionw ith azide-modified proteins and antibodies to afford biosensing platforms. [18] Gobbo et al prepared nanomaterial hybridsb ye mploying ADIBO-functionalized single-walled carbon nanotubes and azide-decorated gold nanoparticles.…”

“…Since its discovery, the SPAAC reaction has been used for the synthesis and/or modification of many materials, including dendrons and dendrimers, topological polymers, organo‐micelles and liposomes, micro‐ and nanoparticles, as well as other material surfaces . More recently, Tsukruk and co‐workers prepared branched polyhedral oligomeric silsesquioxane nanoparticles by the interfacial SPAAC reaction . Yi and co‐workers reported chitosan‐poly(ethylene glycol) microparticles featuring azadibenzocyclooctynes (ADIBO) and their potential to undergo bioconjugation in the SPAAC reaction with azide‐modified proteins and antibodies to afford biosensing platforms .…”

Hierarchical Assembly of Star Polymer Polymersomes into Responsive Multicompartmental Microcapsules

“…The thickness of the microcapsules was determined to be half of the height of the collapsed flat regions of dried microcapsules by NanoScope software. 41 Transmission Electron Microscopy (TEM). TEM was conducted using a JEOL 100CX instrument operated at 100 kV with samples drop cast on carbon-Formvar-coated copper grids (Ted Pella, Inc.).…”