The pH-responsive linear and branched polymers of 2-(diethylamino)ethyl methacrylate (DEAEMA) have successfully been synthesized via atom transfer radical polymerisation (ATRP). New amine functionalized generation 1 and 2 dendrons (G1 and G2) have been used as ATRP initiators in order to confer significant chain-end functionality. Then, stable aqueous nanoparticle (NP) dispersions have been produced for both linear and branched polymers via nanoprecipitation – characterized by dynamic light scattering and scanning electron microscopy. The G1-p(DEAEMA) NPs have successfully been loaded at 10 wt% with fluoresceinamine as a hydrophobic model drug molecule and pharmacological studies have shown promising results with high aggregation in macrophage sites. The G2-p(DEAEMA) has been branched with a pH-responsive brancher, 1,4-butanediol di(methacryoyloxy)-ethyl ether (BDME), to give a double pH triggered system in which the nanoparticles were successfully “degraded” into primary polymer chains, as verified by Gel Permeation Chromatography (GPC). A study has been carried out whereby the encapsulated NPs have released fluoresceinamine upon acid addition through a dialysis membrane – 94% of the encapsulated model drug was released after 8 hours and GPC confirms the linear polymer remaining in the bag following hydrolysis. In addition, the statistical incorporation of monomer units generating hydrophobic domains (such as tert-butyl methacrylate and 2-hydoxypropyl methacrylate) during the polymerisation of DEAEMA allowed the synthesis of branched materials whose hydrophobicity can be tuned. The resulting “double-triggered” NPs will therefore be able to encapsulate a wide variety of drugs.

pH-Responsive hyperbranched-polydendrons for drug delivery applications

250th National Meeting (2015)

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