Identifier

etd-11102009-062412

Degree

Master of Science in Biological and Agricultural Engineering (MSBAE)

Department

Biological and Agricultural Engineering

Document Type

Thesis

Abstract

Improved oral delivery of vitamins and antioxidants via food, beverages or supplements can be achieved by encapsulation of the bioactive component in biodegradable and biocompatible colloidal and nanoparticle systems. Mucoadhesive chitosan/Poly (D, L-lactide-co-glycolide) particles were investigated as a means to control the release of bioactive compounds such as vitamin E in the gastrointestinal (GI) tract. Chitosan/PLGA particles with entrapped alpha-tocopherol at different initial loadings were synthesized by emulsion evaporation method, compared against PLGA particles in terms of their physical properties, stability, and gastrointestinal release profiles. Chi/PLGA particles of 250 ± 8.9 nm with a zeta potential of 61 ± 3.1 mV, and 0.232 polydispersity were formed at 16% theoretical initial loading (with respect to PLGA) and 0.6 w/v% chitosan. Chitosan/PLGA particles were stable below pH 5 and above pH 8; at low pHs particles were positively charged whereas at high pHs they had a negative zeta potential. Particles precipitated between pH 5 and 8. Stability of the particles as function of time revealed that PLGA particles remained stable with an average particle size, zeta-potential and PDI of 120 nm, − 65 mV, 0.3, respectively, over a day under all gastrointestinal conditions, except pH 1.5, where the particle system approached point of zero charge and aggregated. Similarly, Chitosan/PLGA particles aggregated around neutral pHs, but were well dispersed at pH 1.5. The particle release kinetics in simulated gastric and intestinal environments for different initial alpha-tocopherol loadings was studied. Faster alpha-tocopherol release occurred for 8% initial loading under gastric conditions compared to 16% and 24% alpha-tocopherol initial loadings. Initial loading had no significant effect on the intestinal release of αT. The PLGA particle systems also exhibited a faster release rate compared to Chitosan/PLGA particles mostly due to smaller size. 40% alpha-tocopherol was released within 2 hours under gastric conditions, and 54 % released after 5 days under intestinal conditions, from PLGA particles. In comparison, Chi/PLGA particles released only 20 % under gastric and 58 % under intestinal conditions. Hence, Chi/PLGA were found superior in increasing the residence time of alpha-tocopherol in the GI tract which theoretically could be associated with improved αT bioavailability.

Date

2009

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

Sabliov, Cristina M.

DOI

10.31390/gradschool_theses.1703

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