Development, systematic optimisation and biofilm disruption activity of eugenol-based nanosized emulsions stabilised with Tween 80

Abstract

The aims of this study were to systematically optimise a formula for eugenol emulsions via face-centered central composite design and to assess the activity against two-different bacterial strains (Staphylococcus aureus and Propionibacterium acnes) present at planktonic and biofilm forms. The molecular interaction of excipients, mean particle size (MPS) including zeta potential (ZP), drug entrapment efficiency (DEE) and in vitro drug release of optimised emulsions was done using FT-IR, Malvern Zetasizer, ultracentrifugation technique and membrane-free dissolution model, respectively. The emulsions consisted of 151.3 ± 1.45 nm MPS, −21.3 ± 1.25 mV ZP and 93.98 ± 1.41% DEE values. On storage of emulsions at 25 °C for 3 months, the value of DEE was found to be 72.12 ± 2.82%. The Tween 80 emulsifier film coverage onto the dispersed eugenol droplets of emulsions delayed significantly the drug release (12%–19%) compared to the drug release occurred from pure eugenol. The treatment of planktonic S. aureus and P. acnes with diluted eugenol emulsions showed the minimum inhibitory concentration and minimum bactericidal concentration values at 1.25–2.5 mg/ml whereas it occurred at 10 mg/ml for pure eugenol. Treating the biofilms with eugenol emulsions (1–2 mg/ml) yielded 59–70% minimum biofilm eradication concentration but 10 mg/ml pure eugenol showed 60%. Hence, the eugenol emulsions displayed antibacterial activity and could be projected as an antibiofilm or biofilm disruption agent.

Keywords:

• Alamar blue assay
• biofilm
• eugenol
• nanosized emulsions
• planktonic
• Tween 80

Acknowledgements

The authors would like to acknowledge the facilities provided by NIPER, Guwahati, Assam, India for carrying out this research work.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The data and materials will be made available if asked for.

Additional information

Funding

The authors CLP and PC received funding from Department of Pharmaceuticals, Ministry of Chemicals and Fertilisers, Govt. of India. The author SNRR would like to thank the Department of Biotechnology (DBT), Govt. of India for providing the financial support under the Nanotechnology grant (Sanction No. 102/IFD/SAN/2383/2018– 2019, Date: September 19, 2018).