Effect of negative polarity electret on dielectric properties and hypoglycemic effects of insulin / 第二军医大学学报

ABSTRACT

Objective To study the effect of negative polarity electret on the dielectric properties and structure of insulin, and to observe the influence of electrostatic field on the hypoglycemic effect of insulin. Methods Negative polarity electrets of –500, –1 000 and –1 500 V were prepared using polypropylene film by a gate voltage corona charging system, and were used to treat insulin, respectively. The equivalent surface potential of each electret within 48 h was measured by compensation method. The relationship between the polarization of insulin and the electrostatic field was measured by the dielectric constant d33. The influence of the electrostatic field on the molecular structure of insulin was examined by nuclear magnetic resonance and gel electrophoresis. Insulin exposed to –500, –1 000 and –1 500 V negative polarity electret for 12 h was injected into the diabetic rats, and then the hypoglycemic effect of insulin were observed. Results The potential differences between the two sides of insulin solution effected by negative polarity electrets with different surface potentials were exponentially increased within 0-4 h and gradually became constant at 4-48 h. Compared with the insulin patch treated by non-electret electrostatic field, the d33 values of insulin patch effected by –500, –1 000 and –1 500 V electret for 12 h were increased by 14.7 times, 26.7 times and 45.0 times, respectively, and all tended to be stable after 12 h. The spatial structure of insulin exposed to electrostatic field did not change, but the hydrogen bond content of most perssad was decreased; the proportion of monomers of the insulin was increased, and the main structures of the insulin were monomers and dimers. Compared with the electret-free insulin treatment group, the blood glucose content of diabetic rats treated with the –500 V and –1 000 V negative polarity electrets insulin for 8 h were decreased by 50.9% and 22.1%, respectively (P<0.05). Conclusion Negative polarity electret can further improve the hypoglycemic effect of insulin.