A pH-sensitive curcumin loaded microemulsion-filled alginate and porous starch composite gels: Characterization, in vitro release kinetics and biological activity.

To improve the controlled release and stability of the loaded drug, the alginate-porous starch solution, as the gel matrix (GM), was prepared and added into curcumin-loaded microemulsion (CUR-ME) in a certain proportion, and then mixed with slow-gelling agents (CaCO3 + d-glucono-δ-lactone) to prepared curcumin-loaded microemulsion gel (CUR-ME-G). With increasing the proportion of GM from 25% (CUR-ME3G1) to 83% (CUR-ME1G5), the drug loading efficiency increased from 24% to 98% and the maximum drug loading capacity (14.9 mg/g) was found in CUR-ME1G3 with 75% GM. Moreover, a denser structure that entrapped all microemulsion droplets was formed with increasing the proportion of microemulsion according to the observation of scanning electron microscopy. This was also confirmed by Fourier transform infrared spectroscopy and Raman spectroscopy that no new peaks appeared in CUR-ME-G, while the hydrogen bonding interactions might exist between curcumin and sodium alginate. The in vitro release of the CUR-ME-G followed diffusion-controlled mechanism that was consistent with the first-order kinetic model. The release rate depended on the components of the CUR-ME-G and the pH value of the release medium. CUR-ME-G with curcumin concentration of 0.20% exhibited the best biological activity. CUR-ME-G might provide a potential application in the smart drug delivery systems.

Versican and fibrillin-1 form a major hyaluronan-binding complex in the ciliary body.

PURPOSE: In this study, biochemistry, molecular biology, immunohistochemistry, and electron microscopy techniques were used to examine whether versican, which is known to bind fibrillin-1, interacts with fibrillin-1 in the ciliary body and vitreous, and whether the versican in this complex binds to hyaluronan. METHODS: The new polyclonal antibodies against the amino and carboxyl termini of versican were raised and characterized. The mRNA expression levels of versican and fibrillin-1 were analyzed by RT-PCR and real-time PCR, and their protein levels were evaluated by Western blot analysis and immunohistochemistry. Isolation of versican bound to fibrillin-1-containing microfibrils from ciliary bodies was performed by extraction studies. Slot-blot analyses and rotary shadowing electron microscopy were applied to identify versican associated with fibrillin-1-containing microfibrils after gel filtration chromatography and density gradient centrifugation. RESULTS: The newly prepared polyclonal antibodies recognized amino and carboxyl termini of chicken versican. Versican, principally V0 and V1, was found to be securely bound to fibrillin-1-containing microfibrils, forming a major hyaluronan-binding structure in the ciliary nonpigmented epithelium. In addition, Western blot analysis revealed two cleaved complexes, the carboxyl-terminal end of versican bound to fibrillin microfibrils and the amino terminal end of versican bound to hyaluronan in the vitreous body. CONCLUSIONS: Fibrillin-1, versican, and hyaluronan form a unique complex in the ciliary nonpigmented epithelium, and two cleavage products of this complex were shown to exist in the vitreous body. This newly clarified fibrillin-versican-hyaluronan (FiVerHy) complex and its cleavage products may be indispensable for the physiological properties important to the ciliary body and vitreous.