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Updated: Jun 27, 2026
High-throughput Identification of Bacteria Repellent Polymers for Medical Devices
Published on: November 5, 2016
A novel cationic-peptide coating for the prevention of microbial colonization on contact lenses
M D P Willcox1, E B H Hume, Y Aliwarga
1Institute for Eye Research, The University of New South Wales (UNSW), Sydney, NSW, Australia. m.willcox@ier.org.au
Aims:
To develop an antimicrobial peptide with broad spectrum activity against bacteria implicated in biomaterial infection of low toxicity to mammalian cells and retaining its antimicrobial activity when covalently bound to a biomaterial surface.
Methods And Results:
A synthetic peptide (melimine) was produced by combining portions of the antimicrobial cationic peptides mellitin and protamine. In contrast to the parent peptide melittin which lysed sheep red blood cells at >10 microg ml(-1), melimine lysed sheep red blood cells only at concentrations >2500 microg ml(-1), well above bactericidal concentrations. Additionally, melimine was found to be stable to heat sterilization. Evaluation by electron microscopy showed that exposure of both Pseudomonas aeruginosa and Staphylococcus aureus to melimine at the minimal inhibitory concentration (MIC) produced changes in the structure of the bacterial membranes. Further, repeated passage of these bacteria in sub-MIC concentrations of melimine did not result in an increase in the MIC. Melimine was tested for its ability to reduce bacterial adhesion to contact lenses when adsorbed or covalently attached. Approximately 80% reduction in viable bacteria was seen against both P. aeruginosa and S. aureus for 500 microg per lens adsorbed melimine. Covalently linked melimine (18 +/- 4 microg per lens) showed >70% reduction of these bacteria to the lens.
Conclusions:
We have designed and tested a synthetic peptide melimine incorporating active regions of protamine and mellitin which may represent a good candidate for development as an antimicrobial coating for biomaterials.
Significance And Impact Of The Study:
Infection associated with the use of biomaterials remains a major barrier to the long-term use of medical devices. The antimicrobial peptide melimine is an excellent candidate for development as an antimicrobial coating for such devices.
Insights
A novel synthetic antimicrobial peptide, melimine, effectively combats biomaterial infections with low mammalian cell toxicity. This peptide shows significant bacterial reduction when attached to surfaces, offering a promising solution for medical devices.
Area of Science:
- Biomaterials Science
- Antimicrobial Peptides
- Infectious Diseases
Background:
- Biomaterial-associated infections are a significant challenge in medical device longevity.
- Developing effective antimicrobial strategies is crucial for improving patient outcomes and device functionality.
Purpose of the Study:
- To create a broad-spectrum antimicrobial peptide with low mammalian cell toxicity.
- To ensure the peptide retains antimicrobial activity when bound to biomaterial surfaces.
Main Methods:
- A synthetic peptide, melimine, was engineered by combining melittin and protamine sequences.
- Antimicrobial activity, mammalian cell toxicity, heat stability, and bacterial membrane effects were evaluated.
- Melimine's efficacy in reducing bacterial adhesion to contact lenses was tested in adsorbed and covalently attached forms.
Main Results:
- Melimine demonstrated broad-spectrum activity against Pseudomonas aeruginosa and Staphylococcus aureus.
- It exhibited significantly lower toxicity to sheep red blood cells compared to melittin.
- Adsorbed and covalently attached melimine reduced bacterial adhesion to contact lenses by approximately 80% and over 70%, respectively.
- Melimine was stable to heat sterilization and did not induce bacterial resistance.
Conclusions:
- The synthetic peptide melimine shows potential as an antimicrobial coating for biomaterials.
- Its broad-spectrum activity, low toxicity, and surface-binding capabilities make it a promising candidate for preventing biomaterial infections.
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