Pluronics modified liposomes for curcumin encapsulation: Sustained release, stability and bioaccessibility.

The present work evaluated the feasibility of different pluronics (F127, F87 and P85) utilized as modifiers to improve the stability and bioaccessibility of curcumin liposomes (cur-Lps). Pluronics modified curcumin liposomes (cur-pluronic-Lps) were prepared by thin film evaporation combined with dynamic high pressure microfluidization. The particle size and polydispersity index of cur-pluronic-Lps was significantly lower than cur-Lps. Fourier transform infrared spectroscopy analysis revealed that curcumin was loaded in liposomes successfully and X-ray diffraction suggested that curcumin in the liposomes was in an amorphous state. In vitro release studies demonstrated that 73.4%, 63.9%, 66.7% and 58.9% curcumin released from cur-Lps, cur-F127-Lps, cur-F87-Lps and cur-P85-Lps, respectively. Compared with cur-Lps, cur-pluronic-Lps showed a slower release rate and lower cumulative release percentage for curcumin. Non-Fickian transport was the main release mechanism for cur-Lps, cur-F127-Lps and cur-F87-Lps, and typically the first-order model fitted cur-P85-Lps release. Stability studies (exposure to solutions of different pH and heat treatment) indicated that pluronics modification could enhance their pH stability and thermal stability. In vitro simulated gastrointestinal tract studies suggested that pluronics modification could significantly improve the absorption of cur-Lps. Bioaccessibility of curcumin liposomes increased in the following order: cur-Lps < cur-F87-Lps < cur-P85-Lps < cur-F127-Lps. These results may guide the potential application of pluronics modified liposomes as carriers of curcumin in nutraceutical and functional foods.

Characterization and bioavailability of tea polyphenol nanoliposome prepared by combining an ethanol injection method with dynamic high-pressure microfluidization.

Tea polyphenols are major polyphenolic substances found in green tea with various biological activities. To overcome their instability toward oxygen and alkaline environments, tea polyphenol nanoliposome (TPN) was prepared by combining an ethanol injection method with dynamic high-pressure microfluidization. Good physicochemical characterizations (entrapment efficiency = 78.5%, particle size = 66.8 nm, polydispersity index = 0.213, and zeta potential = -6.16 mv) of TPN were observed. Compared with tea polyphenol solution, TPN showed equivalent antioxidant activities, indicated by equal DPPH free radical scavenging and slightly lower ferric reducing activities and lower inhibitions against Staphylococcus aureus , Escerhichia coli , Salmonella typhimurium , and Listeria monocytogenes . In addition, a relatively good sustained release property was observed in TPN, with only 29.8% tea polyphenols released from nanoliposome after 24 h of incubation. Moreover, TPN improved the stability of tea polyphenol in alkaline solution. This study expects to provide theories and practice guides for further applications of TPN.