| In this paper, the stabilizing triblock W/O starch microemulsion has been studied firstly, with the aid of electrical conductance, phase volume and visual phenomena. Starch nanoparticles (SN) have been prepared with W/O starch microemulsion as microreader and epichlorohydrin as cross-linking agent. The factors affecting the preparation of SN have been investigated via the characterization of TEM. The results show that the size and size distribution of SN are mainly controlled by the interfacial strength of microreactor, and the interfacial strength of microreactor is chiefly influenced by W value (the molar ratio of water / surfactant) and concentration of starch. The SN with controllable size and size distribution can be obtained by adjusting preparation parameters. So, it is expected to use the SN as targeted drug carrier.In addition, the preparation of aqueous starch microgel with aqueous solution as reaction environment has been studied. The results show that the important factors affecting the formation of starch microgel are surfactant content, concentration of starch and conversion efficiency of cross-linking reaction. Based on the former research, further optimizing experiments have been carried out with the uniform design and step regression method. The optimum preparation conditions and the predicted quantitative equation have been obtained, which can be used to prepare starch microgel with smaller size and narrower size distribution. It is found that starch microgel has microporous network structure and environmental responsiveness, moreover, its volume phase transition temperature (Tc) is around 37℃, which are researched by the characterization of TEM, DLS , light refraction and other techniques. So, starch microgel with those advantages can be expected to use as a targeting drug carrier.Finally, the properties of the drug-loaded SN have been evaluated with the help of UV spectrophotometer, and with the small molecular and water insoluble drug-sulpiride as a model drug. It is found that the entrapping efficiency of drug-loaded SN in entrapping method can amount to 96.87% and that in adsorption method is 87.63%, which show that the loading mechanism of SN is mainly adsorptive mechanism. The sustained release behavior of drug-loaded SN in PBS has been studied, the results show that the in vitro release curve consists of initial rapid release stage followed by slower exponential stage, and the release profiles can be well modeled using a biexponential and biphasic kinetics function. This drug-loaded SN is of controlled release properties.
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