Kinetics of release and antibacterial activity of salicylic acid loaded into halloysite nanotubes

In this work halloysite (Hal) nanotubes were used as nanocontainers for salycilic acid (SA) in a perspective of its use in active packaging for food industry. The system Hal/SA was investigated for its ability to stabilize Hal suspensions by turbidimetry, its release kinetics in water by UV spectroscopy and its antibacterial activity against Pseudomonas fluorescens IMA 19/5 by Isothermal Micro Calorimetry (IMC). IMC is a sensitive and nondestructive technique and allows the study of a wide range of relatively slow processes (hours and days) in solutions. The system Hal/SA resulted to stabilize Hal suspension in water and to release SA in a controlled way over 50 h. Moreover the SA released by Hal/SA showed an antibacterial activity at lower concentrations than free SA, likely due to the close contact of bacteria and Hal in the reaction vessel.