Counterion-Activated Nanoactuator: Reversibly Switchable Killing/Releasing Bacteria on Polycation Brushes

Abstract

A strategy to release attached bacteria from surface-grafted bactericidal poly((trimethylamino)ethyl methacrylate chloride) (pTMAEMA) brushes has been proposed. The pTMAEMA brushes were fabricated via the surface-initiated atom transfer radical polymerization for contact killing of bacteria, including Escherichia coli, Staphylococcus epidermidis and Stenotrophomonas maltophilia. The bacteria-conditioning surfaces, afterward, were washed with electrolyte solutions containing anions with different lipophilic characteristic, charge density, polarity and adsorbility to quaternary ammonium groups in polymers. Because of the special ion-pairing interactions, the interfacial properties, including wettability and ζ-potential, can be manipulated in a controlled manner. Therefore, the counterion-assisted modulation of pTMAEMA brushes facilitates the bacterial release and regeneration of antimicrobial polymer films. The physicochemical properties of polymer brushes and their interactions with counterions were characterized using an ellipsometer, contact angle goniometer, X-ray photoelectron spectroscopy and an electrokinetic analyzer. The repetitive killing and releasing actions of pTMAEMA through unlocking and locking counterions were demonstrated, showing the robust effectiveness of the pTMAEMA-based nanoactuator in controlling the physical action by the chemical stimuli. The real-world implementation of the nanoactuator was demonstrated with a surgical scalpel by repelling killed bacteria and retaining reusability.

Temperature responsive behavior of polymer brush/polyelectrolyte multilayer composites

“…1,[4][5][6] The important advantages of polymer brushes are the mechanical stability, due to the covalent bonding to the substrate, and the high swelling ratio, which causes a significant thickness change upon switching between swollen and collapsed state in good and bad solvents, respectively. This makes them particularly interesting for controlled release, 7 tunable assembly of coated nanoparticles, 8 responsive nanoactuators 9,10 or for antifouling surfaces. 11,12 More recently, complex systems produced by embedding surfactants, 13,14 gels 15,16 or nanoparticles [17][18][19][20] into polymer brushes have been studied, from which multiresponsive coatings with enlarged applicability as stimuli-responsive systems can be designed.…”

Smart Polymers with Special Wettability

“…[70] Moreover, with the help of unlocking/locking counterions to induce physicochemical changes in polymer conformation and surface wettability, reversible killing/releasing bacteria could be acquired. [71] This counterion-activated strategy is more environmentally friendly, which may be applicable in reusable medical devices and industrial facilities. Although sometimes biofilms on implanted materials are naturally formed, the long-term preservation of bacterial resistance as well as the promotion of mammalian cells adhesion activity remains a formidable challenge.…”

Porous Microstructured Surfaces with pH‐Triggered Antibacterial Properties

“…Accordingly, an ideal antimicrobial surface should prevent bacterial adhesion, kill adhered bacteria in case of contamination and, afterward, clean the surface of dead bacteria (i.e., demonstrate a self‐cleaning capacity). Such smart surfaces should be capable of reversibly varying their surface properties in response to changes in the environment, such as local acidity, the presence of enzymes, temperature, light, or the presence of counterions, among others. Thus, by simple changes in the external conditions, the surfaces can kill adhered bacteria and, subsequently, shed dead bacteria from the surface, cleaning the surface and maintaining long‐term antimicrobial activity.…”