Designing an anti-biofilm agent using ionic liquids with long alkyl chain anion: Synthesis, characterization, and anti-biofilm activity

Date of Publication


Document Type

Master's Thesis

Degree Name

Master of Science in Chemistry


College of Science



Thesis Adviser

Drexel H. Camacho

Defense Panel Chair

Marissa G. Noel

Defense Panel Member

Maria Carmen S. Tan
Reena Jesusa A. Macalalad


A group of microorganisms encased in an extracellular polymeric substance is called biofilm. These biofilms have dire effects on human health and in the industry and this resulted to an active search for compounds that can inhibit biofilm formation. One of the compounds being studied is called ionic liquids. Ionic liquids are salts that have at least one organic ion and have melting point below 100ºC. These compounds can be easily designed depending on the researchers purpose and in this case, as an anti-biofilm agent.

In this study, ionic liquids with long alkyl chain anion, specifically the salt form of stearic acid, and imidazolium-based cation were synthesized. The ionic liquids, 1- methylimidazolium stearate (13) and 1-ethyl-3-methylimidazolium stearate (14), were characterized by determining the melting point, and solubility in different organic solvents. The products were also analyzed using Fourier Transform Infrared Spectroscopy and Mass Spectroscopy. Using two Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and two Gram-positive bacteria (Staphylococcus epidermidis and Bacillus cereus), colorimetric and time-dependent eradication assays were done.

Results showed that (13) and (14) were successfully synthesized and that both ionic liquids exhibit anti-biofilm and biofilm eradication properties. Generally, the higher the concentration of the compounds and the longer the alkyl chain on the cation, the more potent they are. The long alkyl chain anion used is also important because it can penetrate the extracellular polymeric substance which makes the biofilms resistant to antibiotics.

Further studies are recommended to expand the knowledge about ionic liquids as antibiofilm agents.

Abstract Format






Accession Number


Shelf Location

Archives, The Learning Commons, 12F Henry Sy Sr. Hall

Physical Description

xviii, 189 leaves ; 28 cm. + 1 computer optical disc


Biofilms; Fused salts

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