Alginate carrier as a controlled thymol delivery system: Effect of particle size

Thymol, which possesses outstanding pharmacological activities such as anti-inflammatory, antibacterial, antifungal, and antitumor behavior, has a wide range of applications in medical and food packaging fields. This work aimed to conduct a comparison of alginate microparticles and nanoparticles as thymol delivery systems. Alginate was utilized to prepare nanoparticles of size 62.54 nm and microparticles of size 500–600 μm by emulsification and electrospraying methods, respectively. The effect of thymol loading on the characteristics of both particles demonstrated the significant size reduction and decrease of size distribution in thymol-loaded alginate nano/microparticles upon loading thymol to the alginate nano/microparticles. The chemical properties and thermal stability of the synthesized thymol-loaded alginate carriers were investigated by Fourier Transform Infrared and Differential scanning calorimetry; the results exhibit physical entrapment of thymol within the alginate carriers in the absence of any chemical changes in the carriers’ structure. Encapsulation efficiency and loading capacity for thymol-loaded alginate microparticles were calculated as 88.9% ± 1.1% and 8.23% ± 0.8%, correspondingly, while that of thymol-loaded alginate nanoparticles were reported as 98.7% ± 0.6% and 5.75% ± 0.14%, respectively. In vitro drug release recommended that thymol-loaded alginate nanoparticles released thymol in a more sustainable and controllable manner compared to thymol-loaded alginate microparticles, whereas for both of them, Korsmeyer-Peppas kinetic model can be applied, the trend of the Thymol release from the carriers followed a quasi-Fickian diffusion mechanism. Also, both thymol-loaded carriers represented cell viability of about 98% and good antibacterial properties against E. coli and S. aureus in vitro . The fabricated thymol-loaded Alginate Microparticles and thymol-loaded Alginate Nanoparticles can be deployed as promising drug delivery systems. • Thymol-loaded alginate microparticles and nanoparticles were prepared by electrospray and emulsification methods, respectively. • Thymol loading induced more uniform shapes and sizes and reduced the size of the particles. • The results of the thermal and chemical analysis demonstrated the physical entrapping of thymol in particles. • The release profiles from both particles were governed by a Korsmeyer-Peppas mechanism and indicated the quasi-fickian diffusion. • Thymol-loaded alginate nanoparticles can release thymol more slowly and in an extended time compared to microparticle counterparts.