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

Goh , Kar Yin (2021) Development of cellulose-reinforced alginate microbeads for optimal encapsulation and delivery of palm-based vitamin E / Goh Kar Yin. PhD thesis, Universiti Malaya.

	PDF (The Candidate's Agreement) Restricted to Repository staff only Download (114Kb)
	PDF (Thesis PhD) Download (3807Kb)

Abstract

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.

Actions (For repository staff only : Login required)