Abstract: Aim To determine the secondary structure of insulin encapsulated within liposome. Methods The secondary structure of native insulin, mixture of insulin with liposome (sample I) and insulin encapsulated within liposome (sample II) were determined by FTIR (Fourier Transform Infrared) spectroscopy. Results The secondary structure of insulin encapsulated within liposome (II) are similar with the secondary structure of native insulin. The difference existed in the amount of α-helices (from 36% of insulin to 31% of sample II) and β-sheet (from 48% of insulin to 51% of sample II). The content of α-helices and β-sheet of insulin in sample I was found to be very close to that of sample II. The results revealed that the insulin encapsulated within liposome possibly spread on the surface of liposome, without inserting into the liposome membrane. Conclusion The secondary structure of insulin encapsulated within liposome is similar with the native insulin.

Key words: FTIR, FTIR, insulin, insulin, liposome, liposome, secondary structure, secondary structure