食品機能性成分の効率的利用のためのナノ／マイクロキャリアの作製

2015 Fiscal Year Annual Research Report

• Project/Area Number: 15J00406
• Research Institution: University of Tsukuba
• Principal Investigator: OSSAI EMMANUEL 筑波大学, 生命環境科学研究科, 特別研究員(DC2)
• Project Period (FY): 2015-04-24 – 2017-03-31
• Keywords: Multiple emulsion / Microchannel / Lipid vesicles / Entrapment yield / Calcein / Reversed-micelles / Bilayer solubilization / Droplet instability

Outline of Annual Research Achievements

I have successfully investigated the effects of surfactants on the entrapment yield of the hydrophilic molecule - calcein, in lipid vesicles prepared by multiple emulsion method. The experiments were conducted using three different surfactants, Tween 80, Pluronic F68, and BSA, in the W2 phase of W1/O/W2 multiple emulsion prepared using microchannel emulsification technique. Three mechanisms were proposed to explain the stabilization effects of the surfactants with respect to the entrapment yields of the hydrophilic fluorescent marker, calcein. At high concentrations (ca. 3.0 wt%), reversed-micellar transport of calcein from the internal to the external water phase is predominant in Pluronic F68 stabilized lipid vesicles; whereas, for Tween 80 stabilized vesicle suspensions at such high concentration, both destabilization/solubilization effects and reversed-micellar transport of calcein are at play. With decreasing concentrations of the Tween 80, the entrapment yield improves up to certain threshold concentration, below which poor entrapment ensues due to insufficient amount of the surfactant. Hence, calcein - a model of hydrophilic drug - can be efficiently entrapped (ca. 80%) in lipid vesicles at lower concentrations of the food grade surfactant, Tween 80 (ca. 0.1 and 0.05 wt%). The results of this study, therefore, could provide clues on the design of experimental conditions for improved entrapment yields of hydrophilic physiologically active substances.

Current Status of Research Progress

2: Research has progressed on the whole more than it was originally planned.

Reason

The progress of my research is at the expected rate. Though there were little challenges I encountered, just like most researchers, I was able to overcome them in due time. I have successfully determined the best surfactants' indices (type and concentration) needed for optimum entrapment yield of a model hydrophilic drug, calcein, in lipid vesicles. Based on the results so far, I have prepared two manuscripts for publication.

Strategy for Future Research Activity

At present, I have started the encapsulation of bioactive materials based on the current research achievement. I will be working with both hydrophilic an hydrophobic functional materials, namely, 5-fluorouracil (hydrophilic anticancer agent), metformin (hydrophilic oral anti diabetic agent), and glibenclamide (hydrophobic oral anti diabetic agent). Principally, Tween 80 (0.1, 0.05, and 3.0 wt%) would be used as emulsifier in the continuous phase for the encapsulation of the various drugs in lipid vesicles using multiple emulsion method. Similarly, 3.0 wt% each of Plutonic F68 and Casein Na (in place of BSA; both found to have similar yield of entrapment) would also be used.

Research Products

• [Presentation] Surfactant type affects the entrapment yield of hydrophilic molecule in lipid vesicles by multiple emulsion method. (2016)
  • Author(s): Ossai, E.C., Terasawa, J., Horikoshi, K., Kuroiwa, T., Kanazawa, A., Sato, S. and Ichikawa, S.
  • Organizer: Tsukuba Students Research Exchange Workshop.
  • Place of Presentation: University of Tsukuba, Tsukuba, Ibaraki.
  • Year and Date: 2016-03-02 – 2016-03-02
• [Presentation] High efficient entrapment of physiologically active substances in lipid vesicles as carriers using multiple emulsion method (2015)
  • Author(s): Ossai, E.C., Terasawa, J., Horikoshi, K., Kuroiwa, T., Kanazawa, A., Sato, S. and Ichikawa, S.
  • Organizer: The University of Tsukuba-National Taiwan University Joint Mini Symposium.
  • Place of Presentation: National Taiwan University, Taipei, ROC
  • Year and Date: 2015-12-08 – 2015-12-10
  • Int'l Joint Research
• [Presentation] Effects of surfactants on the entrapment yield in lipid vesicles by multiple emulsion method. (2015)
  • Author(s): Ossai, E.C., Terasawa, J., Horikoshi, K., Kuroiwa, T., Kanazawa, A., Sato, S. and Ichikawa, S.
  • Organizer: The 47th Autumn Meeting, Society of Chemical Engineers.
  • Place of Presentation: Hokkaido University, Sapporo, Hokkaido.
  • Year and Date: 2015-09-09 – 2015-09-11
• [Presentation] Preparation of size-controlled lipid vesicles entrapping hydrophilic molecules with high efficiency using multiple emulsions. (2015)
  • Author(s): Ossai, E.C., Terasawa, J., Horikoshi, K., Kuroiwa, T., Kanazawa, A., Sato, S. and Ichikawa, S.
  • Organizer: 12th International Congress on Engineering and Food.
  • Place of Presentation: Convention Centre, Quebec City, Canada.
  • Year and Date: 2015-06-14 – 2015-06-18
  • Int'l Joint Research