Three distinct water structures at a zwitterionic lipid/water interface revealed by heterodyne-detected vibrational sum frequency generation

Lipid/water interfaces and associated interfacial water are vital for various biochemical reactions, but the molecular-level understanding of their property is very limited. We investigated the water structure at a zwitterionic lipid, phosphatidylcholine, monolayer/water interface using heterodyne-detected vibrational sum frequency generation spectroscopy. Isotopically diluted water was utilized in the experiments to minimize the effect of intra/intermolecular couplings. It was found that the OH stretch band in the Imχ((2)) spectrum of the phosphatidylcholine/water interface exhibits a characteristic double-peaked feature. To interpret this peculiar spectrum of the zwitterionic lipid/water interface, Imχ((2)) spectra of a zwitterionic surfactant/water interface and mixed lipid/water interfaces were measured. The Imχ((2)) spectrum of the zwitterionic surfactant/water interface clearly shows both positive and negative bands in the OH stretch region, revealing that multiple water structures exist at the interface. At the mixed lipid/water interfaces, while gradually varying the fraction of the anionic and cationic lipids, we observed a drastic change in the Imχ((2)) spectra in which spectral features similar to those of the anionic, zwitterionic, and cationic lipid/water interfaces appeared successively. These observations demonstrate that, when the positive and negative charges coexist at the interface, the H-down-oriented water structure and H-up-oriented water structure appear in the vicinity of the respective charged sites. In addition, it was found that a positive Imχ((2)) appears around 3600 cm(-1) for all the monolayer interfaces examined, indicating weakly interacting water species existing in the hydrophobic region of the monolayer at the interface. On the basis of these results, we concluded that the characteristic Imχ((2)) spectrum of the zwitterionic lipid/water interface arises from three different types of water existing at the interface: (1) the water associated with the negatively charged phosphate, which is strongly H-bonded and has a net H-up orientation, (2) the water around the positively charged choline, which forms weaker H-bonds and has a net H-down orientation, and (3) the water weakly interacting with the hydrophobic region of the lipid, which has a net H-up orientation.     

Poly(hexamethylene guanidine)‐based hydrogels with long lasting antimicrobial activity and low toxicity

Long lasting antimicrobial activity and low toxicity are essentials for hydrogels in biomedicine. However, most reported hydrogels cannot combine these characteristics. In this work, poly (hexamethylene guanidine) hydrochloride (PHMG), a cheap cationic polymer with two terminal amino groups, was first modified with methacrylic anhydride to give PHMG dimethacrylamide (PHMGDMAAm), which was further used to prepare hydrogels with acrylamide (AAm) under ultraviolet irradiation in the presence of α‐ketoglutaric acid (α‐KGA) as photoinitiator in aqueous medium. The resultant hydrogels showed strong antibacterial activity against both Gram‐negative and Gram‐positive bacteria due to the PHMG segments in the hydrogel backbone. Moreover, the antimicrobial activity of the hydrogels did not decrease significantly after being soaked in water for one month and washed by water frequently for many times. Hemolysis and cytotoxicity assays demonstrated the excellent biocompatibility of the PHMG‐PAAm hydrogels. This kind of low cost cationic hydrogels with long lasting antimicrobial activity and low toxicity is expected to have potential applications in biomedicine. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55, 2027–2035     

Effect of end groups of poly(n-butyl methacrylate) on its biocompatibility

Telechelic poly(n-butyl methacrylate)s (PBMAs) with various end groups were prepared using nonionic, anionic, cationic or zwitterionic azo-type radical initiators and cell adhesion onto the surfaces of the polymers was investigated. The tendency for cell adhesion to the polymers differed with and without pretreatment with phosphate-buffered saline (PBS, pH 7.4). The cell adhesion to polymer surfaces without pretreatment was lower than that with pretreatment. The effect of pretreatment with PBS was significant for PBMA with ionic end groups. Furthermore, cell adhesion to the surface of PBMA with zwitterionic end groups was suppressed compared with that to the surfaces of other polymers. It was presumed that positive and negative charges of zwitterionic groups in the same molecule negated each other at pH 7.4 and that the polymers with zwitterionic end groups had no effective charges. The results clearly indicated that biocompatibility of polymers can be changed by the introduction of functional groups at the ends of the polymer chains. Fabrication of functional material surfaces will be anticipated by the similar method in the future.     

Formation of antifouling functional coating from deposition of a zwitterionic-co-nonionic polymer via “grafting to” approach

We develop a new process for the preparation of synergistic antifouling functional coatings on gold surfaces via a “grafting to” approach. The strategy includes a synthetic step of polymer brushes that consist of poly (ethylene glycol) (PEG) and zwitterionic side chains via a typical reversible-addition fragmentation chain transfer (RAFT) polymerization process, and a subsequent deposition of the polymer brushes onto a gold substrate. The presence of PEG and zwitterion chains on these polymer brush-coated gold surfaces has been proved to have a synergistic effect on the final antifouling property of the coating. PEG chains lower the electrostatic repulsion between zwitterionic polymer chains and increase their graft density on gold surfaces, while zwitterionic polymer effectively improves the antifouling property that is offered by PEG chains alone. Protein adsorption and cell attachment assays tests are conducted to confirm that this copolymer layer on gold surface has a pronounced resistance against proteins such as Bovine serum albumin and Lysozyme. Importantly, the antifouling property can be systematically adjusted by varying the molar ratio of PEG to zwitterionic chains in the final coating copolymer.     

Generic top-functionalization of patterned antifouling zwitterionic polymers on indium tin oxide

This paper presents a novel surface engineering approach that combines photochemical grafting and surface-initiated atom transfer radical polymerization (SI-ATRP) to attach zwitterionic polymer brushes onto indium tin oxide (ITO) substrates. The photochemically grafted hydroxyl-terminated organic layer serves as an excellent platform for initiator attachment, and the zwitterionic polymer generated via subsequent SI-ATRP exhibits very good antifouling properties. Patterned polymer coatings can be obtained when the surface with covalently attached initiator was subjected to photomasked UV-irradiation, in which the C-Br bond that is present in the initiator was broken upon exposure to UV light. A further, highly versatile top-functionalization of the zwitterionic polymer brush was achieved by a strain-promoted alkyne-azide cycloaddition, without compromising its antifouling property. The attached bioligand (here: biotin) enables the specific immobilization of target proteins in a spatially confined fashion, pointing to future applications of this approach in the design of micropatterned sensing platforms on ITO substrates.     

Polymethylmethacrylate derivatives Eudragit E100 and L100: Interactions and complexation with surfactants

Precipitation or coprecipitation of polyelectrolytes has been largely investigated. However, the precipitation of polyelectrolytes via addition of charged and non‐charged surfactants has not been systematically studied and reported. Consequently, the aim of this work is to investigate the effect of different surfactants (anionic, cationic, non‐charged and zwitterionic) on the precipitation of cationic and anionic polymethylmethacrylate polymers (Eudragit). The surfactants effect has been investigated as a function of their concentration. Special attention has been dedicated to the CMC range and to the colloidal characterization of the formed dispersions. Moreover, the effect of salt (NaCl) and pH was also addressed. It is pointed out that non‐ionic and zwitterionic surfactants do not interact with charged Eudragit E100 and L100. For oppositely charged Eudragit E100/SDS and Eudragit L100/CTAB, precipitation occurs, and the obtained dispersions have been characterized in terms of particle size distribution and zeta potential. It was established that the binding of SDS molecules to Eudragit E100 polymer chains is made through the negative charges of the surfactant heads under the CMC value whereas binding of CTAB to Eudragit L100 chains is made at a CTAB concentration 5 times above its CMC. For Eudragit E100/SDS system, a more acidic medium induces aggregation. A same result was observed for the Eudragit L100/CTAB at a more basic pH. Moreover, it was observed that increasing salt concentration (higher than 100 mM) led to aggregation as generally observed for polycations/anionic surfactant systems.     

Bionic antibacterial modification of IOL through SI-RAFT polymerization of P(TOEAC-co-MPC) brushes to prevent PCO and endophthalmitis

Various complications such as posterior capsule opacification (PCO) and endophthalmitis occur after intraocular lenses (IOLs) implantation in cataract surgery. It is urgent to construct antifouling and antibacterial IOLs to lower the incidence of PCO and endophthalmitis. Bionic zwitterionic polymer such as 2-methacryloyloxyethyl phosphorylcholine (MPC) shows excellent performance in resisting nonspecific proteins and bacterial adhesion. In this work, a novel bionic brushes coating containing MPC and N, N, N-trimethyl-2-((4-(2-(4-nonylphenoxy) ethoxy)-4-oxobut-2-enoyl) oxy) ethan-1-aminium chloride (TOEAC), a quaternary ammonium monomer, was prepared onto IOLs using reversible addition–fragmentation chain transfer (RAFT) polymerization method. The P(TOEAC-co-MPC) brushes exhibited excellent antifouling efficiency against bovine serum albumin, Staphylococcus aureus, and human lens epithelial cells. In addition, the P(TOEAC-co-MPC) brushes showed excellent antibacterial and antibiofilm abilities and good biocompatibility. An in vivo study confirmed that the P(TOEAC-co-MPC) brushes effectively prevented PCO and endophthalmitis. Consequently, the P(TOEAC-co-MPC) bionic brushes are promising for IOLs surface modification to resist postoperative complications for long-term implantation.     

Biomimetic silver-containing colloids of poly(2-methacryloyloxyethyl phosphorylcholine) and their film-formation properties

The synthesis of stable dispersions of hybrid colloids comprising copolymers of biocompatible 2-hydroxyethyl methacrylate (HEMA) and zwitterionic, biomimetic 2-methacryloyloxyethyl phosphorylcholine (MPC) incorporating antibacterial AgBF(4) by inverse miniemulsion is described. The prepared hybrid colloids were designed to provide both antibacterial and antifouling properties for the formation of interesting, multifunctional films. The obtained particles had sizes in the range of 130-160 nm with two different weight ratios of MPC to HEMA (1:10 and 2:5) and AgBF(4) contents between 0% and 15%. The silver salt takes on the role of the lipophobe in stabilizing the miniemulsion droplets against Ostwald ripening and is reduced after polymerization to Ag nanoparticles by gaseous hydrazine. Subsequently, the hybrid particles are transformed into smooth and stable films with thicknesses between 145 and 225 nm by simple drop casting and solvent annealing. The dispersions and films were thoroughly characterized by DLS, TEM, SEM, EDX, TGA, UV-vis spectroscopy, ICP-OES, XRD, AFM, and contact angle measurements. After immersion into water, the films did not show detectable leakage of silver, so they could be employed as dual-functional antifouling and antibacterial coatings.     

Electrostatic model for mixed cationic-zwitterionic lipid bilayers

The current interest in mixed cationic-zwitterionic lipid membranes derives from their potential use as transfer vectors in nonviral gene therapy. Mixed cationic-zwitterionic lipid membranes have a number of structural properties that are distinct from the corresponding anionic-zwitterionic lipid membranes. As known from experiment and reproduced by computer simulations, the average cross-sectional area per lipid changes nonmonotonically with the mole fraction of the charged lipid, passing through a minimum at a roughly equimolar mixture. At the same time, the average orientation of the zwitterionic headgroup dipoles changes from more parallel to the membrane plane to more perpendicular. We suggest a simple mean-field model that reveals the physical mechanisms underlying the observed structural properties. To backup the mean-field calculations, we have also performed Monte Carlo simulations. Our model extends Poisson-Boltzmann theory to include (besides the cationic headgroup charges) the individual charges of the zwitterionic lipid headgroups. We model these charges to be arranged as dipoles of fixed length with rotational degrees of freedom. Our model includes, in a phenomenological manner, the changes in steric headgroup interactions upon reorientation of the zwitterionic headgroups. Our numerical results suggest that two different mechanisms contribute to the observed structural properties: one involves the lateral electrostatic pressure and the other the zwitterionic headgroup orientation, the latter modifying steric headgroup interactions. The two mechanisms operate in parallel as they both originate in the electrostatic properties of the involved lipids. We have also applied our model to a mixed anionic-zwitterionic lipid membrane for which neither a significant headgroup reorientation nor a nonmonotonic change in the average lateral cross-sectional area is predicted.     

New antifouling silica hydrogel

In this work, a new antifouling silica hydrogel was developed for potential biomedical applications. A zwitterionic polymer, poly(carboxybetaine methacrylate) (pCBMA), was produced via atom-transfer radical polymerization and was appended to the hydrogel network in a two-step acid-base-catalyzed sol-gel process. The pCBMA silica aerogels were obtained by drying the hydrogels under supercritical conditions using CO(2). To understand the effect of pCBMA on the gel structure, pCBMA silica aerogels with different pCBMA contents were characterized using scanning electron microscopy (SEM), nuclear magnetic resonance (NMR) spectroscopy, and the surface area from Brauner-Emmet-Teller (BET) measurements. The antifouling property of pCBMA silica hydrogel to resist protein (fibrinogen) adsorption was measured using enzyme-linked immunosorbent assay (ELISA). SEM images revealed that the particle size and porosity of the silica network decreased at low pCBMA content and increased at above 33 wt % of the polymer. The presence of pCBMA increased the surface area of the material by 91% at a polymer content of 25 wt %. NMR results confirmed that pCBMA was incorporated completely into the silica structure at a polymer content below 20 wt %. A protein adsorption test revealed a reduction in fibrinogen adsorption by 83% at 25 wt % pCBMA content in the hydrogel compared to the fibrinogen adsorption in the unmodified silica hydrogel.     

咪唑盐类聚离子液体抗菌剂的制备及其在水凝胶敷料中的应用

皮肤伤口的感染严重威胁患者的生命安全,虽然传统的含有银离子或小分子抗生素的抗菌水凝胶伤口敷料具有广谱的杀菌功效,但这些抗菌水凝胶敷料中的抗菌剂存在一定的生物毒性和耐药性风险,无法满足临床长期使用的要求.咪唑盐类聚离子液体由于其含有较强的正电荷效应以及疏水链段,因此其作为新型的聚合物抗菌剂具有较强的抗菌效果.本研究首先通...     

Interactions between sulfobetaine-based polyzwitterions and polyelectrolytes

We investigate the interactions between sulfobetaine-based polyzwitterions and polyelectrolytes, either positive or negative ones, i.e., poly(DADMAC)s and poly(AA)s. Three different sulfobetaine motifs denoted SPE, SPP, and SHPP have been considered, presenting slight chemical changes either in the function carrying the zwitterionic group or in the zwitterionic motif itself. All three poly(sulfobetaine)s normally present critical temperatures (T(c)) above which they become fully soluble. The association with polyelectrolytes directly affects the critical temperature in a highly nonmonotonic fashion as the mixture composition is varied. Thanks to layer-by-layer deposition in a reflectometric cell, we demonstrate that a selective attraction exists between polyzwitterions and polyelectrolytes, from which an association follows at a nanoscopic scale as demonstrated by small-angle X-ray scattering and atomic force microscopy. The association of polyzwitterions with polyelectrolytes, however, is site-specific since it exists only between positive polyelectrolytes (i.e., polycations) and polyzwitterions based on SPE or SPP motifs. The range in which the association affects the critical temperature, T(c), is found to largely depend on the molecular weights of both zwitterionic and cationic species. As a result, the complexation and the creation of a hybrid object, referred to as a complex, also depend on the same parameters. By varying the latter from a few thousands to several millions, we define rules for the existence of this complex. In particular, a minimum polyzwitterion molecular weight is needed to observe alterations of the critical temperatures and closure of the complexation cone. Finally, within a Flory-like approach, we consider the polyzwitterion/polyelectrolyte complex as an effective statistical copolymer, whose composition comprises a fraction phi(A) of excess zwitterionic motifs as the majority species and a fraction 1 - phi(A) of complex motifs. We thereby reduce a polymer/polymer/solvent ternary system to a copolymer/solvent binary one, an assumption valid within the limit of small additions of cationic species. The approach predicts the reciprocal critical temperature 1/T(c) to be quadratic in phi(A), which agrees very well with all experimental results, even for a large mismatch between the molecular weights of both species, and regardless of the zwitterionic motif, SPE or SPP.     

An Adamantyl Amino Acid Containing Gramicidin S Analogue with Broad Spectrum Antibacterial Activity and Reduced Hemolytic Activity

The cyclic cationic antimicrobial peptide gramicidin S (GS) is an effective topical antibacterial agent that is toxic for human red blood cells (hemolysis). Herein, we present a series of amphiphilic derivatives of GS with either two or four positive charges and characteristics ranging between very polar and very hydrophobic. Screening of this series of peptide derivatives identified a compound that combines effective antibacterial activity with virtually no toxicity within the same concentration range. This peptide acts against both Gram‐negative and Gram‐positive bacteria, including several MRSA strains, and represents an interesting lead for the development of a broadly applicable antibiotic.     

原位探测防污高分子材料与液体界面的分子结构

Marine organisms such as plants, algae or small animals can adhere to surfaces of materials that are submerged in ocean. The accumulation of these organisms on surfaces is a marine biofouling process that has considerable adverse effects. Marine biofouling on ship hulls can cause severe fuel consumption increase. Investigations on antifouling polymers are therefore becoming important research topics for marine vessel operations. Antifouling polymers can be applied as coating layers on the ship hull, protecting it against the settlement and growth of sea organisms. Polyethylene glycol (PEG) is a hydrophilic polymer that can effectively resist the accumulation of marine organisms. PEG-based antifouling coatings have therefore been extensively researched and developed. However, the inferior stability of PEG makes it subject to degradation, rendering it ineffective for long-term services. Zwitterionic polymers have also emerged as promising antifouling materials in recent years. These polymers consist of both positively charged and negatively charged functional groups. Various zwitterionic polymers have been demonstrated to exhibit exceptional antifouling properties. Previously, surface characterizations of zwitterionic polymers have revealed that strong surface hydration is critical for their antifouling properties. In addition to these hydrophilic polymers, amphiphilic materials have also been developed as potential antifouling coatings. Both hydrophobic and hydrophilic functional groups are incorporated into the backbones or sidechains of these polymers. It has been demonstrated that the antifouling performance can be enhanced by precisely controlling the sequence of the hydrophobic-hydrophilic functionalities. Since biofouling generally occurs at the outer surface of the coatings, the antifouling properties of these coatings are closely related to their surface characteristics in water. Therefore, understanding of the surface molecular structures of antifouling materials is imperative for their future developments. In this review, we will summarize our recent advancements of antifouling material surface analysis using sum frequency generation (SFG) vibrational spectroscopy. SFG is a surface-sensitive technique which can provide molecular information of water and polymer structures at interfaces in situ in real time. The antifouling polymers we will review include zwitterionic polymer brushes, mixed charged polymers, and amphiphilic polypeptoids. Interfacial hydration studies of these polymers by SFG will be presented. The salt effect on antifouling polymer surface hydration will also be discussed. In addition, the interactions between antifouling materials and protein molecules as well as algae will be reviewed. The above research clearly established strong correlations between strong surface hydration and good antifouling properties. It also demonstrated that SFG is a powerful technique to provide molecular level understanding of polymer antifouling mechanisms.     

Adsorption of protein-coated lipid droplets to mixed biopolymer hydrogel surfaces: role of biopolymer diffusion

The adsorption of charged particles to hydrogel surfaces is important in a number of natural and industrial processes. In this study, the adsorption of cationic lipid droplets to the surfaces of anionic hydrogels was examined. An oil-in-water emulsion containing cationic beta-lactoglobulin-coated lipid droplets was prepared (d32=0.24 microm, zeta=+74 mV, pH 3.0). An anionic hydrogel containing 0.1 wt % beet pectin and 1.5 wt % agar (pH 3.0) was prepared. Emulsions containing different lipid droplet concentrations (0.3-5 wt %) were brought into contact with the hydrogel surfaces for different times (0-24 h). The adsorption of lipid droplets to the hydrogel surfaces could not be explained by a typical adsorption isotherm. We found that the electrical charge on the nonadsorbed lipid droplets became less positive or even became negative in the presence of the hydrogel and that extensive droplet aggregation occurred, which was attributed to the ability of pectin molecules to diffuse through the hydrogels and interact with the lipid droplets. These results may have important consequences for understanding certain industrial and biological processes, as well as for the design of controlled or triggered release systems.     

Removal of cationic dyes by poly(acrylamide-co-acrylic acid) hydrogels in aqueous solutions

Poly(acrylamide-co-acrylic acid (poly(AAm-co-AAc)) hydrogels prepared by irradiating with γ-radiation were used in experiments on swelling, diffusion, and uptake of some cationic dyes such as Safranine-O (SO) and Magenta (M). Poly(AAm-co-AAc) hydrogels irradiated at 8.0 kGy have been used for swelling and diffusion studies in water and cationic dye solutions. The maximum swellings in water, and SO, and M solutions observed are 2700%, 3500%, and 4000%, respectively. Diffusions of water and cationic dyes within hydrogels have been found to be non-Fickian in character. Adsorption of the cationic dyes onto poly(AAm-co-AAc) hydrogels is studied by the batch adsorption technique. The adsorption type was found Langmuir type in the Giles classification system. The moles of adsorbed dye for SO and M per repeating unit in hydrogel (binding ratio, r) have been calculated as 3834×10⁻⁶ and 1323×10⁻⁶, respectively. These results show that poly(AAm-co-AAc) hydrogels can be used as adsorbent for water pollutants such as cationic dyes.     

Coating of vesicles with hydrophilic reactive polymers

Vesicles bearing either cationic (amino) groups or zwitterionic (amino acid) groups on the surface were coated with a reactive multivalent hydrophilic N-(2-hydroxypropyl)methacrylamide polymer (PHPMA) and its positively charged analogue (3 mol % quaternary ammonium groups), both having reactive thiazolidine-2-thione (TT) groups randomly distributed along the polymer chain. The vesicles were dispersed in water at a concentration of 1 mg/mL. The effect of surface charges of model vesicles on the surface coating efficiency was evaluated. The changes in the weight-average molecular weight, in the hydrodynamic size, and in the zeta-potential of model vesicles were tested using light scattering methods. The most effective coating of vesicles was observed for the zwitterionic vesicles coated with the positively charged hydrophilic PHPMA-TT copolymer at a concentration of reactive polymer cp = 2 mg/mL. The coating efficiency was more than 1 order of magnitude higher than that obtained for positively charged vesicles coated by the uncharged hydrophilic polymer at the same cp.     

Self‐Assemblies on Chitosan Nanohydrogels

Nanohydrogels of pure chitosan, containing neither potentially toxic solvent nor chemical cross‐linker, were obtained by an ammonia‐induced physical gelation of a reverse emulsion of a chitosan solution in a triglyceride mixture as an organic phase. The resulting colloids were obtained with a controlled size distribution and displayed a positive surface charge. Assemblies with various macromolecules were investigated as a first step toward new nano‐carriers for bioactive molecules. Chondroitin sulfate formed polyelectrolyte complexes with the positively charged surface of the nanogels, leading to negative chitosan‐based colloidal hydrogels with preservation of the original average size of the dispersion. The mode of assembly of HIV‐1 p24 protein with these colloids relied on multiple interactions between the protein and the hydrogels, irrespective of their surface charges. Anyhow, the amounts of loaded protein remained limited, suggesting a surface association. The assembly of an immunoglobulin (IgG) was markedly different from p24. No association was detected with the positive colloidal hydrogels whereas a very high loading capacity could be obtained with the negative ones. So, this work reports that fully biodegradable submicrometric physical hydrogels could be obtained from naturally occurring polymers. These gels could cargo a variety of biomolecules making them versatile carriers with many potential applications in Life Sciences.

     

Magnetically assisted removal and separation of cationic dyes from aqueous solution by magnetic nanocomposite hydrogels

Magnetic poly(acrylic acid‐acrylamide‐butyl methacrylate) (P(AAB)) nanocomposite hydrogels were prepared and used as adsorbents for removal and separation of cationic dyes from aqueous solution. These magnetic P(AAB) nanocomposite hydrogels were characterized by scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). It was found that these magnetic P(AAB) nanocomposite hydrogels had magnetic responsive characters. The dynamic swelling, removal, and separation of cationic dye, crystal violet (CV), and basic magenta (BM) by these magnetic nanocomposite hydrogels were studied. The adsorption capacity and isotherm studies of cationic dyes onto magnetic P(AAB) nanocomposite hydrogels have been evaluated. The magnetic P(AAB) nanocomposite hydrogels containing Fe₃O₄ particles can be easily manipulated in magnetic field for removal and separation of cationic dyes from aqueous solution. Adsorption process agreed very well with the Langmuir and Freundlich models. Copyright © 2010 John Wiley & Sons, Ltd.     

Integrated zwitterionic conjugated poly(carboxybetaine thiophene) as a new biomaterial platform

An integrated zwitterionic conjugated polymer-based biomaterial platform was designed and studied to address some of the key challenges of conjugated polymers in biomedical applications. This biomaterial platform consists of conjugated polymer backbones and multifunctional zwitterionic side chains. Zwitterionic materials gain electrical conductivity and interesting optical properties through conjugated polymer backbones, and non-biocompatible conjugated polymers obtain excellent antifouling properties, enhanced electrical conductivity, functional groups of bioconjugation and response to environmental stimuli via multifunctional zwitterionic side chains. This platform can potentially be adapted to a wide range of applications (e.g. bioelectronics, tissue engineering and biofuel cell), which require high performance conducting materials with excellent antifouling/biocompatibility at biointerfaces.