Stimulus‐Responsive Polyelectrolyte Surfaces: Switching Surface Properties from Polycationic/Antimicrobial to Polyzwitterionic/Protein‐Repellent

Abstract

Surfaces coated with polyzwitterions are most well-known for their ability to resist protein adsorption. In this article, a surface-attached hydrophobically modified poly(carboxybetaine) is presented. When protonated by changes of the pH of the surrounding medium, this protein-repellent polyzwitterion switches to a polycationic state in which it is antimicrobially active and protein-adhesive. The pH range in which these two states exist are recorded by zeta potential measurements. Adsorption studies at different pH values (monitored by surface plasmon resonance spectroscopy) confirm that the adhesion of protein is pH dependent and reversible, that is, protein can be released upon a pH change from pH 3 to pH 7.4. At physiological pH, the poly(carboxyzwitterion) is antimicrobially active, presumably because it becomes protonated by bacterial metabolites during the antimicrobial activity assay. Stability studies confirm that the here presented material is storage-stable, yet hydrolyses after longer incubation in aqueous media. IntroductionWith an unbroken trend towards increasing bacterial resistance against antibiotics, [1] there is a pressing need for materials that

Optimizing Fouling Resistance of Poly(Sulfabetaine)s through Backbone and Charge Separation

“…[41] Other studies of such spacer effects in polycarboxybetaines by Unsworth and coworkers remained inconclusive, however. [42,43] One inherent problem in interpreting properly the data results from the rather low acidity of the carboxyl moiety, which depends on the inter-charge spacer length and may gradually transform the zwitterionic moiety into a cationic one depending on the environmental pH, [12,44,45] thus changing the fouling potential markedly. In the case of polysulfobetaines, this complication is absent by virtue of the strongly acidic character of the sulfonate group.…”

Multiple strategies to control the hydrophilic–hydrophobic balance of P(DMA-co-DMAEMA-co-QDMAEMA) coatings

“…Stimulated by external stimuli, smart-responsive polymers can change their structure, resulting in changes in their physical and chemical properties. When modifying substrates with stimuli-responsive polymers, the properties of the modified surface, for example pore size, 17 morphology, 18 charge density, 19 and especially wettability, [2][3][4]18,20,21 are affected by the corresponding stimuli. These smart surfaces have received great attention in the fields of biomedical technology, 11,16 oil-water separation, 9,12,[22][23][24] programmable transport, 15,25 antifouling, 17 intelligent soft robotics, 26,27 etc.…”

Poly(oxanorbornene)‐Based Polyzwitterions with Systematically Increasing Hydrophobicity: Synthesis, Physical Characterization, and Biological Properties

“…[9,[15][16][17] Thus, polyzwitterions are considered as bio-inert. This is especially true for polyzwitterions containing pH-inert groups such as sulfonic acid groups and quaternary ammonium groups ("strong electrolyte" groups), but also for those containing pH-responsive carboxylic acid groups (a "weak electrolyte") in combination with quaternary ammonium [20][21][22][23] b) Molecular design of the polyzwitterions reported in this work (right), and the parent structure PZI (left). [20] To increase the hydrolytic stability of the target polymers, the ester bonds of PZI were replaced by amide bonds, and the primary ammonium group was exchanged for quaternary ammonium groups with different alkyl residues.…”

“…Additionally, PZI, IA-PZI, PCB, and PNCB had intrinsic antimicrobial activity. [20][21][22][23] This was remarkable because antimicrobial activity and protein repellency are considered to be mutually exclusive: intrinsic activity against bacteria requires cationic charges, which also induce protein adsorption. To understand this contradiction, the pH-dependent surface zeta potential of these polyzwitterions was studied.…”

“…While that material was protein-adhesive at low pH, an adsorbed protein layer was fully released when the pH value was switched back to neutral. [22] Multi-component polymer systems that were designed for simultaneous protein repellency and antimicrobial activity have also been described in the literature. In most reports of such materials, the desired properties were not fully obtained, that is, either the obtained antimicrobial activity was reduced, or the level of protein repellency was compromised.…”