Development of cellulose-reinforced alginate microbeads for optimal encapsulation and delivery of palm-based vitamin E / Goh Kar Yin

• Main Author: Goh , Kar Yin
• Format: Thesis
• Published: 2021
• Subjects: Q Science (General); QD Chemistry
• Online Access: http://studentsrepo.um.edu.my/14803/1/Goh_Kar_Yin.pdf; http://studentsrepo.um.edu.my/14803/2/Goh_Kar_Yin.pdf; http://studentsrepo.um.edu.my/14803/
• Institution: Universiti Malaya

In this study, pH sensitive microfibrillated cellulose-reinforced alginate microbeads were synthesized for oral administration of vitamin E. Long and network-like hydrophilic microfibrillated celluloses with widths ranging from 8 to 40 nm, having −COOH functional groups were isolated from oil palm empty fruit bunches via ammonium persulfate (APS) oxidation. Cellulose derivatives, hydrophobic trimethylsilyl celluloses with the functional groups of −Si(CH3)3 were also produced via silylation. Palm-based vitamin E was loaded into the oil-in-water emulsions prior to the immobilization into calcium-crosslinked alginate microbeads. The vitamin E-loaded emulsions were first characterized and the influence of the emulsions’ properties on the microbeads were evaluated. Two parameters were manipulated in the production of oil-in-water emulsions: type of cellulose and type of surface-active agents employed in the emulsion stabilization. Oil-in-water emulsions for loading vitamin E were produced using polyoxyethylene glycol sorbitan monooleate (Tween 80):polyoxyethylene lauryl ether (Brij® 35) or 1-butyl-3-methylimidazolium octyl sulfate as surface-active agents with the addition of various concentrations of celluloses (0.0, 0.0125, 0.025, 0.05, 0.1, 0.175, 0.25, 0.5 and 1.0 %w/v). Two distinct natures of celluloses were utilized in this study, which are hydrophilic APS-oxidized celluloses or hydrophobic trimethylsilyl celluloses. The emulsions were evaluated for the average droplet diameter, viscosity and rheological behaviors. Emulsions stabilized by Tween 80:Brij 35, using hydrophilic APS-oxidized celluloses as nanofillers were observed to exhibit the smallest average droplet sizes with moderate rheological properties. Whereas, emulsions stabilized by hydrophobic trimethylsilyl cellulose, employing 1.5 % w/v Tween 80:Brij 35 (0.5:0.5 w/w ratio) as surface active agents exhibited nanometer scale droplet diameters with most remarkable rheological behaviors. In the contrary, the emulsions employing 1-butyl-3-methylimidazolium octyl sulfate as emulsifier showed micron range droplet sizes with poor rheological behavior regardless the concentration of APS-oxidized cellulose. Alginate microbeads were then fabricated by dripping vitamin E-loaded emulsions into crosslinking solution. Results showed that highest compressive strength of 58.8 kPa was obtained for microbeads containing Tween 80:Brij 35-stabilized emulsions with 0.25% w/v hydrophilic oxidized celluloses. This indicated that APS-oxidized celluloses participate in the formation of densely packed and three-dimensional matrix structures of microbeads by interacting with calcium ions via their -COO− groups. Likewise, the highest encapsulation efficiency of 98.7% was also achieved by the 0.25% APS-oxidized cellulose reinforced alginate microbeads containing Tween 80:Brij 35-stabilized emulsion. In addition, the alginate/cellulose microbeads were more resistant against swelling in low pH condition because of the enhanced stability promoted by the bio-based celluloses. The microbeads showed slow release of vitamin E in the simulated gastric pH fluid but tend to release in the simulated intestinal pH fluid to allow the absorption of the drug. However, APS-oxidized cellulose-reinforced alginate microbeads containing 1-butyl-3-methylimidazolium octyl sulfate-stabilized emulsions exhibited lower encapsulation efficiency with unusual high in vitro release of vitamin E. In vitro drug release data of all the evaluated microbeads were fitted well into Ritger-Peppas model. 1H NMR spectra showed that vitamin E retained its chemical structure after encapsulation into alginate-based microbeads.