Encapsulation of magnetic nanoparticles in PEG-PL(G)A polymers of different block lengths via flash nanoprecipitation Nesrine Bali 1 , Felix Bogdan 1 , Reema Ansar 2 , Sulalit Bandyopadhyay 1 1 Particle Engineering Centre, NTNU Norwegian University of Science, Norway 2 School of Chemical and Materials Engineering, National University of Sciences and Technology, Islamabad, Pakistan Flash nanoprecipitation (FNP) is a well-established method to design nanomaterials for a wide range of fields including solar energy conversion, catalysts and nanomedicine. Its procedural simplicity, low cost and easy up- scaling make it a technique of choice for the industrial production of nanomaterials. The principle of this technique relies on the lack of solubility of a compound, a polymer in this case, when injected into a non-solvent phase where it is forced to precipitate. The turbulent mixing conditions and the addition of surfactant molecules allow respectively the formation and the stabilization of the newly formed polymeric nanoparticles. A certain number of studies have been undertaken to encapsulate hydrophobic iron oxide nanoparticles (IONPs) into polymeric nanoparticles (PNPs), but no similar work has been done for hydrophilic IONPs. Contrary to the former, the latter type of IONPs can be easily functionalized with sub-cellular targeting moieties that would only be uncovered after the polymer degradation inside the cell under specific conditions. Hence, the current project aims at encapsulating hydrophilic superparamagnetic IONPs in bio-compatible polymeric nanoparticles using Flash Nanoprecipitation (FNP) in a multi-inlet vortex mixer (MIVM). Poly(ethylene glycol)-poly(lactide) (PEG-PLA) and poly(ethylene glycol)-poly(lactide-co-glycolide) (PEG-PLGA) block copolymers of various block lengths are synthesized through ring-opening polymerization (ROP) in the presence of the biocompatible organic catalyst 1,8-diazabicyclo(5.4.0)undec-7-ene (DBU). The coating of IONPs is then carried out at different ratios of IONPs/ polymers and in the presence of various surfactants to form nanoparticles of 50-200 nm imaged by Transmission Electron Microscopy (TEM). Dynamic Light Scattering (DLS) measurements are conducted over time to show the superior stability of PEG-PLGA NPs over PEG-PLA NPs. It is hypothesized that the relatively higher hydrophilicity of PLGA chains gave more time to their arrangement into micelles and subsequent stabilization by PEG corona. The incorporation of IONPs revealed to be successful in reducing Ostwald ripening behavior of PNPs, while granting hyperthermia properties for such systems to be used for targeted and controlled drug delivery.
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© The Author(s), 2023
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