Microspheres of essential oil in polylactic acid and poly(methyl methacrylate) matrices and their blends

Abstract

This study is focussed on micro-encapsulation of essential oils in polylactic acid (PLA) and a poly(methyl methacrylate) (PMMA) matrix as well as blends of the same. Microspheres were prepared by the solvent evaporation technique and characterised by scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Fourier transform infra-red spectroscopy (FTIR). The encapsulation efficiencies and release profiles of the essential oils were studied by gas chromatography mass spectrometry (GC-MS) and head-space solid-phase microextraction GC-MS, respectively. Furthermore, the microspheres were tested for antibacterial activity against both Gram-negative and Gram-positive bacterial strains.

The results showed that the microspheres compositions (PLA/PMMA ratio) have significant effect on their characteristics. The process adopted for preparing the microspheres promoted formation of spherical particles at the sizes of 1.5–9.5 µm. The highest encapsulation efficiency of the prepared microspheres was observed in systems consisting of linalool (81.10 ± 10.0 wt. % for PLA system and 76.0 ± 3.3 wt. % for PMMA system). Confirmation was also made that the release rate of the microspheres was affected by the size of the same.

Keywords:

• Microspheres
• linalool
• 4-allylanisole
• trans-anethole
• essential oils
• optical properties
• antibacterial properties
• polylactic acid
• poly(methyl methacrylate)
• release study
• oil-in-water solvent evaporation technique

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was financially supported by the Ministry of Education, Youth and Sports of the Czech Republic [grant nos. LO1504 and CZ.1.05/2.1.00/19.0409], and the Internal Grant Agency of TBU in Zlin [grant no. IGA/CPS/2018/003].