Abstract:

Insulin loading into the HII mesophases was examd. as a function of its concn., with addn. of glycerol as a cosolvent and with addn. of phosphatidylcholine (PC) as a structural stabilizer. The structural properties, the mol. interactions, the viscoelastic properties, and the dynamic behavior were investigated by SAXS, ATR-FTIR, and rheol. measurements. Insulin release was then monitored and analyzed. Insulin incorporation into the HII systems shrank the cylinders as it competed with the lipids in water-bonding. Insulin interrupted the interface while increasing $\tau$max and creating a more solid-like response. Upon addn. of PC, cooperative flow behavior was detected, which is probably the reason for increase in insulin cumulative release from 28% to 52% after 300 min. In the presence of glycerol, the system was less cooperative but insulin was more compactly folded, resulting in a slight improvement in insulin release (up to 6%). Addn. of both PC and glycerol caused the max. release (55%). The addn. of additives into the HII system demonstrates how structural modifications can improve insulin release, and influence future design of encapsulated drug delivery systems. [on SciFinder(R)]