Incorporating antioxidative peptides within nanofibrous delivery vehicles: Characterization and in vitro release kinetics

L-carnosine (Car), an antioxidative dipeptide, is a promising health-promoting bioactive agent, which can be isolated from animal waste. In the present study, Car loaded pullulan (Pul)-sodium alginate (NaAlg) based nanofibrous delivery vehicles were fabricated by uniaxial, coaxial and emulsion electrospinning. The CaCl₂ crosslinking was applied after electrospinning process to evaluate the effect on release behavior of Car. Results showed that Car was successfully loaded in water-in-oil-in-water (W₁/O/W₂) double emulsion to produce nanofibers by emulsion electrospinning. Encapsulation efficiencies were found to be 74.11% and 81.69% for the uniaxial (UENFs) and coaxial nanofibers (CENFs), respectively. Encapsulation efficiency was determined for different formulas of emulsions, whereas among the samples that could form nanofibers (NFs) and encapsulate Car, the highest value was obtained for nanofibers from emulsion-VIII (EE-VIII NFs) at 68.63%. DPPH and CUPRAC assays revealed that all electrospinning methods demonstrated protective effect on the antioxidant activity of Car and thus helped in enhancing its antioxidant potential significantly. According to in vitro digestion results, the release of Car from all electrospun NFs was predominantly controlled by Fickian diffusion mechanism. The CaCl₂ crosslinking treatment improved water resistance of NFs and enhanced sustained release of Car in the gastrointestinal tract. The initial burst release of Car from EE-VIII NFs was significantly lower than for UENFs and CENFs in the gastric phase, and the release from EE-VIII NFs in the intestinal phase was followed by sustained release, with/without crosslinking treatment. It can therefore be said that the simultaneously encapsulation of Car in double emulsion and in Pul-NaAlg based electrospun NFs can provide sustained release.