Antibacterial Coatings of Poly(ethylenimine)/Poly(<scp>l</scp>-lactide)-Grafted Hyaluronic Acid Multilayers Surface-Functionalized with Bacteriophages

The infestation of tissue after implantation is a major problem as a bacterial biofilm can form on the surface of the implants, leading to implant-associated infections (IAIs). One approach to prevent such IAI is to apply antibacterial coatings consisting of polyelectrolyte multilayers (PEM) and bacteriophages (PHAGs). PEM were constructed by alternately adsorbing oppositely charged polyelectrolytes on a substrate according to the layer-by-layer concept. Poly(ethylenimine) (PEI) was used as the cationic polyelectrolyte, and a graft polymer of hyaluronic acid and poly(l-lactide) (DAC) was used as the anionic polyelectrolyte. Comparing PEM-5 (PEI/DAC/PEI/DAC/PEI) and PEM-6 (PEI/DAC/PEI/DAC/PEI/DAC), a higher amount of PHAG was bound to PEM-5 with cationic surface charge, which was detected by atomic force microscopy (AFM) measurements and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. The binding of PHAG to the PEM is suggested to be based on electrostatic interactions between the anionic capsid proteins of PHAG and the outermost PEM surface. For antibacterial tests, PEM-5 and PEM-6 each with and without contact to PHAG were deposited at agar plates and infected with bacteria. For the coatings consisting of PEM and PHAG, a significant eradicative effect toward bacteria was obtained, while the pure PEM coatings showed no eradication, which proves the dominant antibacterial contribution originated by PHAG.