In this paper, we report a novel method to synthesize polyethylenimine (PEI) nanogels in the range of 80— 200nm with narrow size distribution by photo-chemistry at room temperature in aqueous solution. The nanogels’ size, size distributions and zeta potential were determined by photo correlation spectroscopy (PCS). Spherical morphology of the nanogels was characterized by scanning electron microscopy (SEM) and confirmed by atomic force microscopy (AFM). The nanogels are of high stability, low toxicity and low immunogenicity, as having been confirmed in in vivo tests with mice as animal model, and in vitro tests with human lung and liver cancer cells as well. Efforts are being made for further studies on synthesis and applications of the nanogels.
Photo-induced Fenton reaction was utilized in this paper to control the sizes of polyethylenimine hydrogels （M-PEIs,M,Fe atom） as gene delivery vector.H2O2 and FeCl2 were mixed with PEI prepolymer in water in a 3-neck quartz flask, and the mixture was stirred vigorously.M-PEIs nanogels dispersed very well in water could be prepared under illumination by use of low-pressure Hg lamps at room temperature.This system was protected from oxygen with N2.By changing reaction conditions,such as the pH value,reaction time and concentrations of solutes,sizes of M-PEIs nanogels could be controlled.It was found that the sizes of M-PEIs decreased with the pH value and the concentrations of FeCl2.The increasing of the initiator （H2O2） concentrations would make the particles more tighten,but might result in crosslinking or degradation of particles.A suitable irradiation time ensured formation of homogeneous nanogel products,but prolonged irradiation would cause degradation of nanogels.After photo crosslinking,the products were purified with membrane filters of 0.45 μm and treated further by dialysis bags with size exclusion below 10 kDa in order to make them more stable for storage.
