Antimicrobial peptides (AMPs) are an interesting class of antibiotics characterized by their unique antibiotic activity and lower propensity for developing resistance compared to common antibiotics. They belong to the class of membrane-active peptides and usually act selectively against bacteria, fungi and protozoans. AMPs, but also peptide conjugates containing AMPs, have come more and more into the focus of research during the last few years. Within this article, recent work on AMP conjugates is reviewed. Different aspects will be highlighted as a combination of AMPs with antibiotics or organometallic compounds aiming to increase antibacterial activity or target selectivity, conjugation with photosensitizers for improving photodynamic therapy (PDT) or the attachment to particles, to name only a few. Owing to the enormous resonance of antimicrobial conjugates in the literature so far, this research topic seems to be very attractive to different scientific fields, like medicine, biology, biochemistry or chemistry.

In this study, the efficacy of electron beam irradiation versus chemical coupling for yielding polyethersulfone (PES) membranes with antibacterial properties was investigated. For the surface coating, a recently discovered lead compound, IL-KKA, comprising a short peptide sequence functionalized with imidazolium groups, was used. For better integration within the membrane, several novel variants of IL-KKA were generated. Membrane immobilization was achieved using different doses of electron beam irradiation and NHS/EDC chemical coupling. Physicochemical characterization of the coated membranes was performed by water contact angle measurements, X-ray photoelectron spectroscopy, and scanning electron microscopy. Our results show that electron beam irradiation is as effective and gentle as chemical coupling using the NHS/EDC method. Moreover, it was demonstrated that the obtained membranes exhibit promising antibacterial activity against B. subtilis. In summary, the technique presented herein might be promising as a template for developing future anti-biofilm devices.