Development of chitosan membrane containing chimeric endolysin (CHAP-amidase) with boosted antibacterial efficiency against Methicillin-Resistant Staphylococcus aureus for enhanced wound healing

Subject Areas : Applied smart materials

Sahar Sarbandi ¹ , Sepideh Khaleghi ^{2 *} , Hossein Fahimi ³ , Hamed Haddad Kashani ⁴

1 - Department of Biotechnology, TeMS.C., Islamic Azad University, Tehran, Iran.
2 - Department of Biotechnology, TeMS.C., Islamic Azad University, Tehran, Iran.
3 - Department of Genetics, TeMS.C., Islamic Azad University, Tehran, Iran.
4 - Anatomical Sciences Research Center, Institute for Basic Sciences, Kashan University of Medical Sciences, Kashan, Iran.

Received: 2025-02-14 Accepted : 2026-03-10 Published : 2026-03-14

Keywords: Endolysin, CHAP-amidase, Chitosan membrane, antibacterial efficiency, MRSA,

Abstract :

Background: The increasing prevalence of multidrug-resistant pathogens hinders effective wound healing. An alternative approach to treat such infection is utilizing phage endolysins which possess broad antimicrobial efficacy even against drug-resistant strains such as methicillin-resistant S. aureus (MRSA). Chitosan-based structures are wildly used as a wound dressing and can be used as a drug carrier for antimicrobial therapeutics. This study develops and evaluates a chitosan-based membrane conjugated with a chimeric endolysin (CHAP-amidase) as a smart drug delivery system with the application as a wound dresser. 

Methods: The coding gene sequence of the chimeric CHAP-amidase was subcloned into the pET-22(+) expression vector and expressed in the E. coli BL21 (DE3) strain. Affinity chromatography was applied to purify the recombinant protein and CHAP-amidase was visualized by SDS-PAGE and western blotting. The chitosan membrane was synthesized by the ionic gelation method and CHAP-amidase attachment was done by non-covalent ionic interaction. Then morphology of membrane was characterized using SEM microscopy imaging. The antibacterial efficiency of chitosan membrane containing CHAP-amidase (CMCA) was evaluated against Staphylococcus aureus (S. aureus), MRSA, E. coli, and Enterotoxigenic E. coli (ETEC) pathogens by MIC.

Results: CMCA has significantly reduced the cell count of S. aureus and MRSA by 3- and 4-folds respectively after 15 min. Moreover, the CMCA showed greater lytic efficiency against all tested pathogens compared with chitosan membrane and CHAP-amidase alone after 120 min. Although the CHAP-amidase was not effective against E. coli and ETEC, the effect of CMCA on both pathogen’s cell counts was significant.

Conclusion: Regarding the excellent antibacterial activity of CMCA against S. aureus and MRSA and the ideal properties of chitosan for wound dressing application the CMCA could be applied as a potential wound dresser.

Keywords: Endolysin; CHAP-amidase; Chitosan membrane; antibacterial efficiency; MRSA

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