Yeast Viability in HLD-NAC-Designed Fully Dilutable Lecithin-Linker Microemulsions.

Area of Science:

• Biochemistry
• Materials Science
• Cell Biology

Background:

• Previous attempts at cell preservation using microemulsions (µEs) in the 1990s were limited by biocompatibility issues and short cell survival times (≤3 days).
• Developing stable and effective microemulsion formulations for long-term cell viability remains a challenge.

Purpose of the Study:

• To explore the efficacy of fully dilutable self-microemulsifying delivery systems (SMEDS) as a novel cell preservation medium.
• To formulate and characterize lecithin-linker microemulsions (LLMs) using specific surfactant blends and evaluate their impact on yeast viability.

Main Methods:

• Formulation of SMEDS using lecithin (Le) and polyglycerol-10-caprylate (PG10C) at a 2/5 ratio, mixed with ethyl oleate (EOL) to create a D60 dilution line.
• Dilution of D60 SMEDS with 0.9% NaCl to form LLMs, characterized using hydrophilic-lipophilic-difference (HLD) and net-average curvature (NAC) models.
• Assessment of LLM properties (bicontinuity, viscosity, conductivity) and yeast activity/viability at varying aqueous contents.

Main Results:

• LLMs with 5%-60% aqueous content were predicted to be bicontinuous, confirmed by viscosity and conductivity measurements.
• Optimal yeast activity and viability were observed at 30% aqueous content, balancing metabolite transport and nutrient supply.
• Low water activity in SMEDS induced yeast dormancy, ensuring survival for at least 10 weeks.

Conclusions:

• Lecithin-linker microemulsions (LLMs) offer a promising solution for long-term cell preservation, extending viability to at least 10 weeks.
• The formulation achieved through SMEDS balances essential factors for cell survival, including nutrient delivery and controlled dormancy.
• This approach overcomes historical limitations in microemulsion-based cell preservation, paving the way for future applications.