Wrinkling on stimuli-responsive functional polymer surfaces as a promising strategy for the preparation of effective antibacterial/antibiofouling surfaces

Biocompatible smart interfaces play a crucial role in biomedical or tissue engineering applications, where their ability to actively change their conformation or physico-chemical properties permits finely tuning their surface attributes. Polyelectrolytes, such as acrylic acid, are a particular type of smart polymers that present pH responsiveness. This work aims to fabricate stable hydrogel films with reversible pH responsiveness that could spontaneously form wrinkled surface patterns. For this purpose, the photosensitive reaction mixtures were deposited via spin-coating over functionalized glasses. Following vacuum, UV, or either plasma treatments, it is possible to spontaneously form wrinkles, which could increase cell adherence. The pH responsiveness of the material was evaluated, observing an abrupt variation in the film thickness as a function of the environmental pH. Moreover, the presence of the carboxylic acid functional groups at the interface was evidenced by analyzing the adsorption/desorption capacity using methylene blue as a cationic dye model. The results demonstrated that increasing the acrylic acid in the microwrinkled hydrogel effectively improved the adsorption and release capacity and the ability of the carboxylic groups to establish ionic interactions with methylene blue. Finally, the role of the acrylic acid groups and the surface topography (smooth or wrinkled) on the final antibacterial properties were investigated, demonstrating their efficacy against both gram-positive and gram-negative bacteria model strains (E. coli and S. Aureus). According to our findings, microwrinkled hydrogels presented excellent antibacterial properties improving the results obtained for planar (smooth) hydrogels.This research was funded by FONDECYT Grant N◦ 1170209. Thanks to FONDEQUIP N◦ EQM150101 for the use of FE-SEM facilities. J. Rodriguez-Hernandez acknowledges financial support from Ministerio de Ciencia, Innovación y Universidades (Project RTI2018-096328-B-I00). C.M. Gonzalez-Henriquez also acknowledges project L318-02 (UTEM) “Concurso de Fortalecimiento para Equipamiento Científico y Tecnológico, Convocatoria 2018” for plasma exposure system acquisition. M.A. Sarabia and C. García-Herrera acknowledge the financial support given by Universidad de Santiago de Chile through Project DICYT 052116GH_POSTDOC. Finally, this study was funded by VRAC Grant Number LPR20-03 and L318-02 of Universidad Tecnológica Metropolitan