Robust synthesis of nanogel particles by an aggregation-crosslinking method

Abstract

A simple and robust method for fabricating polyethyleneimine (PEI) nanogel particles has been developed. The particles were synthesized by crosslinking PEI with dibromoethane (DBE) in organic solvents (nitromethane or dimethylformamide). Stable colloidal dispersions were obtained at elevated temperature and in solvents which provide the highest rate of the PEI alkylation reaction, steric and electrostatic mechanisms of stabilization of nanoparticles. The size of the particles swollen in water ranges from 125 to 500 nm and can be regulated by the conditions of the synthesis (solvent and concentrations of PEI and DBE). The particles respond to pH changes with a 10–15% change in diameter. Uptake and, triggered by the changes in pH, release of a model anionic dye, Rose Bengal, by the particles was associated with the electrostatic interaction of the dye with the charged gel. The encapsulating capacity of the particles with respect to the Rose Bengal was determined to be 1.56 × 10⁻⁴M of the dye per 1 mg of the gel.