Formulation and Characterization of Poly(methyl methacrylate) Microcapsules Encapsulating Peppermint and Origanum Essential Oils

Abstract

Introduction: Peppermint and origanum essential oils are known for their strong antimicrobial, antifungal, and
antibiofilm properties. Despite their effectiveness, their clinical use is limited due to high volatility, poor water solubility,
and instability under environmental conditions. Microencapsulation using biocompatible polymers like poly(methyl
methacrylate) (PMMA) can help overcome these limitations by improving stability and enabling controlled release.
Materials and Methods: Microcapsules were prepared using a modified solvent evaporation method. A mixture
of peppermint and origanum oils in a 100:75 ratio was combined with PMMA in dichloromethane. This organic
phase was emulsified into an aqueous phase containing 1% polyvinyl alcohol and 2 g sodium lauryl sulfate. The
mixture was stirred for solvent evaporation, followed by centrifugation to isolate the microcapsules. The capsules
were then analyzed for ultraviolet (UV) absorbance, particle size, morphology, yield, and entrapment efficiency (EE).
Results: UV-visible spectrophotometry showed λmax at 253 nm for peppermint oil and 276 nm for origanum oil.
BIOVIS microscopy revealed that 99.24% of the capsules were in the 0.5–5 µm range. SEM images showed spherical
particles with smooth surfaces and no cracks. The yield was 70%, with 1050 mg recovered from 1500 mg. EE ranged
from 33.39% to 50.64%, with 37.83–45.00% for peppermint oil and 27.58–58.00% for origanum oil. Discussion: The
PMMA microencapsulation method effectively produced uniform and stable microcapsules. The particle size and
surface morphology support their potential for controlled delivery. Moderate entrapment efficiencies suggest room
for optimization, possibly influenced by differences in the physicochemical properties of the oils. Overall, the method
showed promise in enhancing oil stability and reducing volatility. Conclusion: PMMA-based microencapsulation
successfully stabilized peppermint and origanum oils, offering good yield, structure, and encapsulation efficiency.
This system holds potential for future applications in controlled-release formulations for antimicrobial therapies.