Zwitterionic Conducting Polymers: From Molecular Design, Surface Modification, and Interfacial Phenomenon to Biomedical Applications

Abstract

Conducting polymers (CPs) have gained attention as electrode materials in bioengineering mainly because of their mechanical softness compared to conventional inorganic materials. To achieve better performance and broaden bioelectronics applications, the surface modification of soft zwitterionic polymers with antifouling properties represents a facile approach to preventing unwanted nonspecific protein adsorption and improving biocompatibility. This feature article emphasizes the antifouling properties of zwitterionic CPs, accompanied by their molecular synthesis and surface modification methods and an analysis of the interfacial phenomenon. Herein, commonly used methods for zwitterionic functionalization on CPs are introduced, including the synthesis of zwitterionic moieties on CP molecules and postsurface modification, such as the grafting of zwitterionic polymer brushes. To analyze the chain conformation, the structure of bound water in the vicinity of zwitterionic CPs and biomolecule behavior, such as protein adsorption or cell adhesion, provide critical insights into the antifouling properties. Integrating these characterization techniques offers general guidelines and paves the way for designing new zwitterionic CPs for advanced biomedical applications. Recent advances in newly designed zwitterionic CP-based electrodes have demonstrated outstanding potential in modern biomedical applications.

Facile surface functionalization of triboelectric layers via electrostatically self-assembled zwitterionic molecules for achieving efficient and stable antibacterial flexible triboelectric nanogenerators

“…3c), which might be associated with its high tendency for molecular self-aggregation because of strong intermolecular interactions between the opposite charges of NDSB. 38 Similar results have been obtained with a variety of zwitterions, as reported previously. 25 In addition to this, we surmised that the TENG performance was fundamentally limited by a low degree of NDSB molecular ordering on the substrate, especially for the sulfonate-terminal segment, which could cause the undesired surface dipole moments.…”

Recent Advances in Antifouling Surface Polymer Brushes

“…In recent years, significant progress has been made in the development of antifouling electrochemical biosensors by surface modification of antifouling polymer brushes. ,− These innovative polymer coatings have emerged as powerful solutions to mitigate biofouling and enhance the performance and reliability of the biosensors. By providing a hydration layer on the surface of the biosensors, the polymer brushes such as PEG or zwitterionic polymers can greatly minimize nonspecific adsorption of biomolecules to the sensors and render the sensors with high sensitivity in complex biological conditions. − For instance, Hu et al used eATRP to polymerize SBMA on the surface of glucose oxidase based glucose sensors . They demonstrated that the coating of antifouling PSBMA brushes could reduce by 99% the nonspecific protein adsorption to the sensors and that the sensor maintained 94% sensitivity after exposure to serum-rich conditions for 15 days .…”

Electrified Interactions of Polyzwitterions with Charged Surfaces: Role of Dipole Orientation and Surface Potentials

“…Accordingly, hydration layers can be formed through these strong interactions among zwitterion moieties and water as long as the polyzwitterions are well arranged to create a stable interface. These interactions are believed to be the origin of the powerful antifouling properties of polyzwitterions, making them highly applicable in various practical settings. − …”