Surface coating nanoarchitectonics for optimizing cytocompatibility and antimicrobial activity: The impact of hyaluronic acid positioning as the outermost layer

Polyelectrolyte multilayers (PEMs) based on hyaluronic acid (HA) and poly (diallyldimethylammonium chloride) (PDDA) were deposited on oxidized polystyrene (PS_ox) via the layer-by-layer (LbL) method. The X-ray photoelectron spectroscopy (XPS) confirmed the PEM deposition on PS_ox, and atomic force microscopy (AFM) indicated that the surface roughness of PS also increased after PEM deposition. The PEMs significantly enhanced PS wettability, reducing the contact angle from 73° on PS to 24° on PDDA-terminated (PDDA/HA)_2.5 PEM (2.5 bilayers, 5 layers) and 36° on HA-terminated (PDDA/HA)₃ PEM (3 bilayers, 6 layers). The HA-terminated (PDDA/HA)₃ PEM demonstrated antimicrobial activity. Compared to uncoated PS surfaces, this PEM reduced the surface coverage of viable P. aeruginosa cells from 36.5 % to 3.7 % and S. aureus cells from 13.3 % to 2.5 % on uncoated PS surfaces. The antimicrobial assay following the JIS Z 2801-2010 standard demonstrated that the PDDA-terminated (PDDA/HA)_2.5 PEM inhibited S. aureus growth by 48 %, compared to 32 % inhibition by the HA-terminated (PDDA/HA)₃ PEM relative to the uncoated and non-oxidized polystyrene (PS) surface (control). HA-terminated PEM demonstrated lesser antimicrobial activity than PDDA-terminated PEM. However, both PEMs were cytocompatible against erythrocytes and human adipose-derived stem cells (ADSCs), indicating their potential for biomedical applications, particularly prosthetic coatings.