Temperature scanning ultrasonic velocity study of complex thermal transformations in solid lipid nanoparticles

Area of Science:

• Colloid and surface science
• Materials science
• Physical chemistry

Background:

• Solid lipid nanoparticles (SLNs) are crucial in drug delivery and other applications.
• Understanding their thermal transitions (crystallization and melting) is vital for stability and performance.
• Conventional methods like differential scanning calorimetry (DSC) are widely used but can have limitations.

Purpose of the Study:

• To investigate the utility of temperature scanning ultrasonic velocity measurements for monitoring thermal transitions in triglyceride SLNs.
• To compare the effectiveness of ultrasound velocity measurements with DSC for analyzing SLN phase behavior.
• To assess the potential of ultrasound as an alternative to DSC for colloidal systems.

Main Methods:

• Preparation of tripalmitin-based SLN emulsions.
• Cooling and heating cycles (75°C to 5°C and 5°C to 75°C) at a controlled rate (0.3°C/min).
• Measurement of ultrasonic velocity (u) and differential scanning calorimetry (DSC) heat flow as a function of temperature.

Main Results:

• Excellent correspondence was observed between ultrasound-derived (ΔΔu/ΔT vs. T) and DSC-derived (heat flow vs. T) thermal transition curves.
• Both techniques detected the complex melting behavior of tripalmitin within the SLNs.
• The melting point dependence on particle size was evident in both measurement sets.

Conclusions:

• Temperature scanning ultrasonic velocity measurements are a viable method for monitoring complex thermal transitions in SLNs.
• Ultrasound velocity measurements offer a promising alternative to DSC for phase transition analysis in colloidal systems.
• This technique provides valuable insights into the physical chemistry of SLNs and their thermal behavior.