Controlled-release of curcumin from poly(lactide-co-glycolide) acid/albumin/curcumin and silica/albumin/curcumin drug-delivery systems

Abstract

In drug-delivery systems, the drug carriers should meet several prerequisites such as biocompatibility, biodegradability and lack of immune system activation, in order to play an effective role. In this study, a comprehensive attempt has been carried out to investigate the plausible intermolecular interactions of new drug-delivery systems, by correlating the drug release kinetic with the different types of carriers used. A hydrophilic metal oxide, silica (SiO2), was used as the inorganic carrier, while poly(lactide-co-glycolide) (PLGA), a hydrophobic polyester, was used as the organic carrier. Based on these materials, the designed drug-delivery systems were SiO2/albumin/curcumin (SiO2/Alb/Cur) and PLGA/albumin/curcumin (PLGA/Alb/Cur), where albumin was used as the co-carrier, while curcumin as the hydrophobic model drug. The release of curcumin was proved to be controlled by the addition of albumin in the systems. It was expected that by using different kinds of carriers, different drug release patterns will be obtained, since the properties of the carriers can then influence the intermolecular interactions within the systems. Thus, the study of the intermolecular interaction of SiO2/Alb/Cur systems was carried out by varying SiO2 and albumin composition, and using different sources of SiO2. Besides that, the study of the intermolecular interaction of PLGA/Alb/Cur was also done using different pretreatment methods and dispersion media of PLGA. The release experiments of albumin and curcumin were conducted via in-vitro procedures and phosphate buffer solution (pH 7) was used as the medium. The amounts of albumin and curcumin desorbed from the systems at different time intervals were monitored by UV-Visible spectroscopy (UV-Vis). The samples were characterized using diffuse reflectance UV-visible (DR-UV) spectroscopy, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), specific surface area analysis and differential scanning calorimetry (DSC). The in-vitro studies show that the release of albumin and curcumin from SiO2/Alb/Cur system is dependent on the compositions of SiO2 and albumin, and the source of SiO2 used (tetraethoxysilane (TEOS) and fumed silica). The release of albumin and curcumin was correlated with the intermolecular interaction between SiO2, albumin, and curcumin. The addition of albumin as the co-carrier caused an increase in the total cumulative release amount of curcumin, suggesting that there was a competition between albumin and curcumin to interact with either SiO2 or PLGA. Here, it was demonstrated that the amount of curcumin released was strongly affected by the carriers used. The use of SiO2 as the carrier showed that release of curcumin followed pseudo-second order kinetics, while the use of PLGA showed a first-order kinetic at 49 h. It is concluded that a sustained and controlled drug release system can be achieved by using SiO2 as the carrier. The different strategies and intermolecular interactions described here may be useful in designing a sustainable and controlled drug release system that can meet the medical demands of pharmaceutical applications.