Hydration State Variation of Polyzwitterion Brushes through Interplay with Ions

Effects of Carbon Spacer Length on Conformational Transitions and Protein Adsorption of Polyzwitterions

The properties of polyzwitterions are closely linked to their carbon spacer length (CSL) between oppositely charged groups. A thorough understanding of the effect of CSL on the properties of polyzwitterion-functionalized membranes is important for their fouling resistance and separation performances. In this work, polyzwitterion-functionalized membranes with different CSLs are prepared by coupling selective swelling-induced pore generation with zwitterionization, and the investigation is focused on comprehending the molecular mechanisms underlying protein resistance and conformational transitions within polyzwitterions under varying CSLs. The zwitterionized films show an enhancement in the surface negative potential with the increase of CSL, attributed to the negatively charged groups distanced from the positively charged groups. Quartz crystal microbalance with dissipation (QCM-D) demonstrates that zwitterionized films with different CSLs display distinct levels of resistance to protein adsorption. The trimethylamine N-oxide-derived polymer (PTMAO, CSL = 0) zwitterionized film shows the highest resistance compared to the poly(3-[dimethyl(2'-methacryloyloxyethyl] ammonio) ethanesulfonate (PMAES, CSL = 2) zwitterionized film and the poly(sulfobetaine methacrylate) (PSBMA, CSL = 3) zwitterionized film, owing to its electrical neutrality and pronounced hydrophilicity. Moreover, analysis of the anti-polyelectrolyte behaviors reveals that PTMAO does not undergo a significant conformation transition in deionized water and salt solutions, while the conformations of PMAES and PSBMA display to be more salt-dependent as the CSL increases, attributed to their increased polarization and dipole moment. As a result, the permeability of zwitterionized membranes exhibits enhanced salt responsiveness with the increase in CSL. The findings of this study are expected to facilitate the design of adsorption-resistant surfaces desired in diverse fields.

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

The zwitterionic groups possess strong dipole moments, leading to inter- or intrachain interactions among zwitterionic polymers. This study aims to demonstrate the interaction of polyzwitterions poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC), and poly(carboxybetaine methacrylate) (PCBMA) with electrified surfaces, despite their electrically neutral nature. We studied the adsorption of polyzwitterions and their monomers on electrified surfaces by using an electrochemical quartz crystal microbalance with dissipation (EQCM-D). The interaction between zwitterionic molecules and charged surfaces is explored by adjusting the surface potentials. Interestingly, the adsorption of polyzwitterions can be influenced by external potential, primarily due to the formation of polyzwitterions restricting the mobility of zwitterionic groups, affecting the adsorption behavior of polyzwitterions based on the surface potential. The impact is determined by the arrangement of positive and negative ions within the zwitterionic groups, which are the dipole orientation. Additionally, surface potentials determine the adsorption rate, amount, and chain conformation of the adsorbed thin polyzwitterion layers. The effect of ionic strength was investigated by introducing electrolytes into the aqueous solutions to assess the range of influenced surface potentials.

Tribological Behavior of Sulfonated Polyether Ether Ketone with Three Different Chemical Structures under Water Lubrication

With the development of the shipbuilding industry, it is necessary to improve tribological properties of polyether ether ketone (PEEK) as a water-lubricated bearing material. In this study, the sulfonated PEEK (SPEEK) with three distinct chemical structures was synthesized through direct sulfonated polymerization, and high fault tolerance and a controllable sulfonation degree ensured the batch stability. The tribological and mechanical properties of SPEEK with varying side groups (methyl and tert-butyl) and rigid segments (biphenyl) were compared after sintering in a vacuum furnace. Compared to the as-made PEEK, as the highly electronegative sulfonic acid group enhanced the hydration lubrication, the friction coefficient and wear rate of SPEEK were significantly reduced by 30% and 50% at least without affecting the mechanical properties. And lower steric hindrance and entanglement between molecular chains were proposed to be partially responsible for the lowest friction behavior of SPEEK with methyl side groups, making it a promising and competitive option for water-lubricated bearings.

Zwitterionic Polysulfobetaine Inhibits Cancer Cell Migration Owing to Actin Cytoskeleton Dynamics

Cell migration is an essential dynamic process for most living cells, mainly driven by the reorganization of actin cytoskeleton. To control actin dynamics, a molecular architecture that can serve as a nucleator has been designed by polymerizing sulfobetaine methacrylate. The synthesized zwitterionic polymer, poly(sulfobetaine methacrylate) (PZI), effectively nucleates the polymerization process of G-actin and substantially accelerates the rate of polymerization. Isothermal titration calorimetry (ITC) and bioinformatics analysis indicated binding between PZI and monomeric G-actin. Thus, in vitro actin dynamics was studied by dynamic light scattering (DLS), pyrene-actin polymerization assay, and total internal reflection fluorescence microscopy (TIRFM). Furthermore, a 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) fluorophore-containing monomeric unit was incorporated into the sulfobetaine zwitterionic architecture to visualize the effect of polymer in the cellular environment. The BODIPY-containing zwitterionic sulfobetaine polymer (PZI-F) successfully penetrated the cell and remained in the lysosome with minimal cytotoxicity. Confocal microscopy revealed the influence of this polymer on the cellular actin cytoskeleton dynamics. The PZI-F polymer was successfully able to inhibit the collective migration of the human cervical cancer cell line (HeLa cell) and breast cancer cell line (MDA-MB-231 cell), as confirmed by a wound healing assay. Therefore, polyzwitterionic sulfobetaine could be explored as an inhibitor of cancer cell migration.

Unraveling the Adhesion Behavior of Different Cell Lines on Biomimetic PEDOT Interfaces: The Role of Surface Morphology and Antifouling Properties

The poly(3,4-ethylenedioxythiophene) (PEDOT) interface, renowned for its biocompatibility and intrinsic conductivity, holds substantial potential in biosensing and cellular modulation. Through strategic functionalization, PEDOT derivatives can be adaptable for multifaceted applications. Notably, integrating phosphorylcholine (PC) groups into PEDOT, mimicking the hydrophilic headgroups from cell membranes, confers exceptional antifouling properties on the coating. This study systematically investigated biomolecule interactions with distinct forms of PEDOT, incorporating variations in surface modifications and structure. Zwitterionic PEDOT-PC was electropolymerized on smooth and nanostructured surfaces using various feeding ratios in electrolytes to finely control the antifouling properties of the interface. Precise electropolymerization conditions governed the attainment of smooth and nanostructured filamentous surfaces. The study employed a quartz crystal microbalance with dissipation (QCM-D) to assess protein binding behavior. Bovine serum albumin (BSA), lysozyme (LYZ), cytochrome c (cyt c), and fibronectin (FN) were used to evaluate their binding affinities for PEDOT films. FN, a pivotal extracellular matrix component, was included for connecting to cell adhesion behavior. Furthermore, the cellular adhesion behaviors on PEDOT interfaces were evaluated. Three cell lines─MG-63 osteosarcoma, HeLa cervical cancer, and fibroblast NIH/3T3 were examined. The presence of PC moieties significantly altered the adhesive response, including the number of attached cells, their morphologies, and nucleus shrinkage. MG-63 cells exhibited the highest tolerance for PC moieties. A feeding ratio of PEDOT-PC exceeding 70% resulted in cell apoptosis. This study contributes to understanding biomolecule adsorption on PEDOT surfaces of diverse morphologies and degrees of the antifouling moiety. Meanwhile, it also sheds light on the responses of various cell types.

Influence of Ionic Strength and Specific Ion Effects on Polyelectrolyte Multilayer Films with pH-Responsive Behavior

Layer-by-layer assembled multilayer films have shown great potential for different applications owing to their responsive behavior. Herein, we systematically investigated the effects of composition, salt concentration, and ion specificity on the pH responsiveness of covalently crosslinked chitosan and alginate dialdehyde multilayer films. The changes in film swelling were measured using ellipsometry from low (0.01 mM) to high (3 M) salt (NaCl or NaSCN) concentrations at pH 3, 6, and 9. The swelling responses to increasing ionic strength matched the swelling responses observed for polyzwitterionic and weak monocomponent polyelectrolyte films and depended on the multilayer composition, pH, and ion specificity. Finally, we used the ellipsometric data to demonstrate that the pH responsiveness of such multilayer films, as measured using a quartz crystal microbalance with dissipation monitoring, strongly depends on the ionic condition under which the responses were measured. We thus show that erroneous conclusions about the pH responsiveness of polyelectrolyte multilayer films can be easily obtained if the ionic environment of the application does not closely resemble the ionic condition under which the pH responsiveness is tested.

Effect of Hydrophobicity and Salt on the Temperature Responsiveness of Polymeric Micelles Consisting of Hydrophobic and Sulfobetaine Chains

The effect of the hydrophobicity of the core part and salt on the temperature responsiveness of polymeric micelles composed of sulfobetaine and hydrophobic blocks was investigated. Poly(sulfopropyl dimethylammonium propylacrylamide) (PSPP) was used as the sulfobetaine; poly(2-ethylhexyl acrylate) (PEHA), poly(n-butyl acrylate) (PnBA), poly(ethyl acrylate) (PEA), or poly(n-hexyl acrylate) (PnHA) was used as the hydrophobic polymer. Measurement of the transmittance revealed that the transition temperature of the sulfobetaine homopolymer could be controlled by adjusting the concentration, the degree of polymerization (DP), and the concentration of the added salt. The effect of the anionic species of the added salt due to the chemical structural properties of the sulfobetaine chain was consistent with the order of ionic species with strong structural destruction in the Hofmeister series. The temperature response and micelle formation behavior of the polymeric micelles according to the hydrophobicity of the core part and the preparation method were examined by static light scattering (SLS), fluorescence measurement with pyrene, dynamic light scattering (DLS), transmittance, and atomic force microscopy (AFM). Micelles that had EHA (solubility in water was 0.01 g/100 mL) as the core and did not show temperature responsiveness expressed temperature responsiveness at a lower hydrophobicity (solubility of nBA in water was 0.14 g/100 mL). nBA-b-SPP did not show temperature responsiveness due to the block ratio. However, when micelles were prepared by dialysis, smaller and more stable micelles could be formed in an equilibrium state, and temperature responsiveness was observed. Their transition temperature can be controlled by adjusting the ratio of the sulfobetaine blocks, the hydrophobicity of the core part, the concentration of the polymer aqueous solution, and the concentration of the added salt. Furthermore, like the sulfobetaine homopolymer, the effect depended on the anionic species of the added salt.

Ion-Specific Antipolyelectrolyte Effect on the Swelling Behavior of Polyzwitterionic Layers

In this study, we systematically investigate the interactions between mobile ions generated from added salts and immobile charges within a sulfobetaine-based polyzwitterionic film in the presence of five salts (KCl, KBr, KSCN, LiCl, and CsCl). The sulfobetaine groups contain quaternary alkylammonium and sulfonate groups, giving the positive and negative charges. The swelling of the zwitterionic film in the presence of different salts is compared with the swelling behavior of a polycationic or polyanionic film containing the same charged groups. For such a comparative study, we design cross-linked terpolymer films with similar thicknesses, cross-link densities, and charge fractions, but with varying charged moieties. While the addition of salt in general leads to a collapse of both cationic and anionic films, the presence of specific types of mobile anions (Cl^-, Br^-, and SCN^-) considerably influences the swelling behavior of polycationic films. We attribute this observation to a different degree of ion-pair formations between the different types of anionic counterions and the immobile cationic quaternary alkylammonium groups in the films where highly polarizable counterions such as SCN^- lead to a high degree of ion pairing and less polarizable counterions, such as Cl^-, cause a low degree of ion pairing. Conversely, we do not observe any substantial effect of varying the type of cationic counterions (K⁺, Li⁺, and Cs⁺), which we assign to the lack of ion pairing between the weakly polarizable cations and the immobile anionic sulfonate groups in the films. In addition, we observe that the zwitterionic films swell with increasing ionic strength and the degree of swelling is anion dependent, which is in agreement with previous reports on the "antipolyelectrolyte effect". Herein, we explain this ion-specific swelling behavior with the different cation and anion abilities to form ion pairs with quaternary alkylammonium and sulfonate in the sulfobetaine groups.

Fouling Resistance and Release Properties of Poly(sulfobetaine) Brushes with Varying Alkyl Chain Spacer Lengths and Molecular Weights

We examined the effects of alkyl carbon spacer length (CSL) and molecular weight on fouling resistance and release properties of zwitterionic poly(sulfobetaine methacrylate) brushes. Using surface-initiated atom transfer radical polymerization, we synthesized two series of brushes with CSL = 3 and 4 and molecular weight from 19 to 1500 kg ·mol^-1, corresponding to dry brush thickness from around 6 to 180 nm. The brush with CSL = 3 was nearly completely wet with water (independent of molecular weight), whereas the brush with CSL = 4 exhibited a strong increase in water contact angle with molecular weight. Though the two-brush series had distinct wetting properties, both series of brushes exhibited similarly great resistance against fouling by Staphylococcus epidermidis bacteria and Aspergillus niger fungi spores when submerged in water, indicating that neither molecular weight nor CSL strongly affected the antifouling behavior. We also compared the efficacy of brushes against fouling by fungi and silicon oil in air. Brushes grafted to filter paper were strongly fouled by fungi and silicon oil in air. Grafting the polymers to the filter paper, however, greatly enhanced removal of the foulant upon rinsing. The removal of fungi and silicon oil when rinsed with a salt solution was enhanced by 219 and 175%, respectively, as compared to a blank filter paper control. Thus, our results indicate that these zwitterionic brushes can promote foulant removal for dry applications in addition to their well-known fouling resistance in submerged conditions.

Biomimetic materials based on zwitterionic polymers toward human-friendly medical devices

This review summarizes recent research on the design of polymer material systems based on biomimetic concepts and reports on the medical devices that implement these systems. Biomolecules such as proteins, nucleic acids, and phospholipids, present in living organisms, play important roles in biological activities. These molecules are characterized by heterogenic nature with hydrophilicity and hydrophobicity, and a balance of positive and negative charges, which provide unique reaction fields, interfaces, and functionality. Incorporating these molecules into artificial systems is expected to advance material science considerably. This approach to material design is exceptionally practical for medical devices that are in contact with living organisms. Here, it is focused on zwitterionic polymers with intramolecularly balanced charges and introduce examples of their applications in medical devices. Their unique properties make these polymers potential surface modification materials to enhance the performance and safety of conventional medical devices. This review discusses these devices; moreover, new surface technologies have been summarized for developing human-friendly medical devices using zwitterionic polymers in the cardiovascular, cerebrovascular, orthopedic, and ophthalmology fields.

Zwitterionic Poly(carboxybetaine) Brush/Albumin Conjugate Films: Structure and Lubricity

Artificial cartilages build up a highly lubricious system with the harmony of biomacromolecules and water. Bioconjugate thin films composed of a zwitterionic poly(carboxybetaine methacrylate) (PCB) brush platform and bovine serum albumin (BSA) were designed. BSA conjugation to the PCB brush chains was achieved by carbodiimide chemistry to give PCB brush/BSA conjugate films. The PCB brush/BSA conjugate films exhibited adaptable interfacial properties due to the amphiphilic nature of BSA. Neutron reflectivity showed that BSAs were localized at the liquid side of the conjugate films in PBS and the BSA conjugation slightly reduced the water content of the top layer, while the swollen state of the carpet PCB brush layer remained unchanged. The PCB brush/BSA conjugate films showed improved lubricity in the boundary lubrication mode but slightly worse fluid lubrication induction properties. This conjugate film could be a model system for the investigation of zwitterion/protein composite interfaces and is worth developing biomaterials that require lubrication in vivo.

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

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.

Cononsolvency of Poly[2-(methacryloyloxy)ethyl phosphorylcholine] in Ethanol-Water Mixtures: A Neutron Reflectivity Study

Molecular mechanisms underlying the cononsolvency, a re-entrant coil-to-globule-to-coil conformational transition of polymer chains in mixtures of two good solvents, of poly[2-(methacryloyloxy)ethyl phosphorylcholine] (PMPC) in ethanol-water binary mixtures were complementarily investigated. This was accomplished by following a statistical mechanical model for competitive hydrogen bonding combined with the cooperative solvation concept as well as neutron reflectivity (NR) experiments employing contrast variation in the cononsolvents. The experimental re-entrant aggregation of the PMPC chains in ethanol-water mixed solvents, obtained on the basis of turbidity was accurately reproduced by theoretical calculations. The calculation proved the relatively strong cooperativity of ethanol and the preferential interaction of water, while the total coverage of solvents was the lowest at an ethanol volume fraction (f_ethanol) of 0.90. At this level, the cononsolvency was the most significant, and the collapsed PMPC chains were solvated with more water than the bulk mixed solvent. The ethanol-water cononsolvency for the PMPC brushes on a planar silicon wafer was investigated by NR experiments, and the solvent composition involved in the collapsed PMPC brush was addressed according to the contrast variation study with mixed solvents of water, deuterium oxide, ethanol-d₅, and ethanol-d₆. The collapsed PMPC brushes at f_ethanol = 0.90 contained more water than the bulk solvent. The preferential distribution of water in the collapsed PMPC brush was consistent with the simulation results. Therefore, the molecular mechanism for the cononsolvency of PMPC in ethanol-water mixed solvents based on competitive hydrogen bonding coupled with cooperative solvation was experimentally rationalized.

Structure and pH-Induced Swelling of Polymer Films Prepared from Sequentially Grafted Polyelectrolytes

We have prepared a series of ampholytic polymer films, using a self-initiated photografting and photopolymerization (SI-PGP) method to sequentially polymerize first anionic (deuterated methacrylic acid (dMAA)) and thereafter cationic (2-aminoethyl methacrylate (AEMA)) monomers to investigate the SI-PGP grafting process. Dry films were investigated by ellipsometry, X-ray, and neutron reflectometry, and their swelling was followed over a pH range from 4.5 to 10.5 with spectroscopic ellipsometry. The deuterated monomer allows us to separate the distributions of the two components by neutron reflectometry. Growth of both polymers proceeds via grafting of solution-polymerized fragments to the surface, and also the second layer is primarily grafted to the substrate and not as a continuation of the existing chains. The polymer films are stratified, with one layer of near 1:1 composition and the other layer enriched in one component and located either above or below the former layer. The ellipsometry results show swelling transitions at low and high pH but with no systematic variation in the pH values where these transitions occur. The results suggest that grafting density in SI-PGP-prepared homopolymers could be increased via repeated polymerization steps, but that this process does not necessarily increase the average chain length.

Modulation of Double Zwitterionic Block Copolymer Aggregates by Zwitterion-Specific Interactions

Transformable double hydrophilic block copolymer assemblies are valid as a biocompatible smart macromolecular system. The molecular mechanisms in the spontaneous assembly of double zwitterionic diblock copolymers composed of a poly(carboxybetaine methacrylate) (PCB2) and a poly(sulfobetaine methacrylate) (PSB4) chains (PCB2-b-PSB4) were investigated by the modulation of the aggregates in response to nondetergent zwitterions. The PCB2-b-PSB4 diblock copolymers with a high degree of polymerization PSB4 block produced aggregates in salt-free water through "zwitterion-specific" interactions. The PCB2-b-PSB4 aggregates were dissociated by the addition of nondetergent sulfobetaine (SB4) and carboxybetaine (CB2) molecules, while the aggregates showed different aggregation modulation processes for SB4 and CB2. Zwitterions with different charged groups from SB4 and CB2, glycine and taurine, hardly disrupted the PCB2-b-PSB4 aggregates. The PCB2-b-PSB4 aggregate modulation efficiency of SBs associated with the intercharge hydrocarbon spacer length (CSL) rather than the symmetry with the SB in the PSB chain. These zwitterion-specific modulation behaviors were rationalized based on the nature of zwitterions including partial charge density, dipole moment, and hydrophobic interactions depending on the charged groups and CSL.

Combination of AFM and Electrochemical QCM-D for Probing Zwitterionic Polymer Brushes in Water: Visualization of Ionic Strength and Surface Potential Effects

The surface modification of soft zwitterionic polymer brushes with antifouling properties represents a facile approach to enhancing the performance of bioelectronics. Ionic strength and applied potentials play a crucial role in controlling polymer brushes' conformation and hydration states. In this study, we quantitatively investigated and compared poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) and poly(sulfobetaine methacrylate) (PSBMA) brushes at different salt concentrations and applied surface potentials. Initiator-containing poly(3,4-ethylenedioxythiophene) films (poly(EDOT-Br)) were prepared by electropolymerization. After the conducting polymer was deposited, polymer brushes grew from the electrode surface through surface-initiated atom-transfer radical polymerization (SI-ATRP). Polymer brushes were carefully characterized for their surface morphologies using an atomic force microscope (AFM). The force volume method measured using AFM enabled the analysis of the Young's modulus of the two polymer brushes. Hydration states and protein binding behaviors of polymer brushes were examined using quartz crystal microbalance with dissipation (QCM-D). We further integrated a potentiostat with the QCM-D to conduct an electrochemical QCM-D study. The energy dissipation and frequency changes corresponded to the ion adsorption on the film surface under different ionic strengths. The results of both hydration states and nonspecific protein binding behavior indicate that PMPC brushes have greater ionic strength independency, implying the conformation of the unchanged PMPC brushes. Moreover, we illustrated how the surface potential influences nonspecific and specific binding behavior on PMPC brushes on PEDOT films compared with electrified poly(EDOT-PC) electrodes. We concluded that PMPC brushes exhibit unique behaviors that are barely affected by ion concentration, and that the brushes' modification results in less influence by surface potential due to the finite Debye length influencing the electrode surface to outer environment in an NaCl aqueous solution.

Application of Zwitterionic Polymer Hydrogels to Optical Tissue Clearing for 3D Fluorescence Imaging

Zwitterionic polymers have both anion and cation groups in the side chain and have been used in various biomedical applications because of the unique properties. In this study, zwitterionic polymer hydrogels are applied to optical tissue clearing for 3D fluorescence imaging. Polyacrylamide hydrogels have been employed in Clear Lipid-exchanged Acrylamide-hybridized Rigid Imaging/Immunostaining/In situ-hybridization-compatible Tissue-hYdrogel method. Zwitterionic polymer hydrogels are produced using zwitterionic monomers, such as 3-[(3-acrylamidopropyl)dimethylammonio]propane-1-sulfonate (DAPS) and 2-methacryloyloxyethyl phosphorylcholine (MPC), and crosslinkers. The hydrogels made from poly(DAPS-co-acrylamide) and MPC homopolymers afford the most transparent tumor tissues. However, the tissues cleared using DAPS copolymers-containing hydrogels became turbid in a refractive index-matching solution, which are unable to obtain clear 3D fluorescence images. In contrast, the 3D fluorescence imaging is achieved in the MPC polymer-treated 2-mm-thick brain slices after immunostaining. The 3D fluorescence imaging of lung metastasis that is cleared by the MPC hydrogel to demonstrate the possible application to cancer diagnosis is performed. The results indicate the increased potentials of zwitterionic polymer hydrogels, especially MPC polymer hydrogels, in biomedical applications.

Sulfobetaine Methacrylate Polymers of Unconventional Polyzwitterion Architecture and Their Antifouling Properties

Combining high hydrophilicity with charge neutrality, polyzwitterions are intensely explored for their high biocompatibility and low-fouling properties. Recent reports indicated that in addition to charge neutrality, the zwitterion's segmental dipole orientation is an important factor for interacting with the environment. Accordingly, a series of polysulfobetaines with a novel architecture was designed, in which the cationic and anionic groups of the zwitterionic moiety are placed at equal distances from the backbone. They were investigated by in vitro biofouling assays, covering proteins of different charges and model marine organisms. All polyzwitterion coatings reduced the fouling effectively compared to model polymer surfaces of poly(butyl methacrylate), with a nearly equally good performance as the reference polybetaine poly(3-(N-(2-(methacryloyloxy)ethyl)-N,N-dimethylammonio)propanesulfonate). The specific fouling resistance depended on the detailed chemical structure of the polyzwitterions. Still, while clearly affecting the performance, the precise dipole orientation of the sulfobetaine group in the polyzwitterions seems overall to be only of secondary importance for their antifouling behavior.