Zwitterionic Groups Research Articles

Cografting of Zwitterionic Sulfobetaines and Cationic Amines on β-Cyclodextrin-Threaded Polyrotaxanes Facilitates Cellular Association and Tissue Accumulation with High Biocompatibility.

β-Cyclodextrins (β-CDs) and β-CD-containing polymers have attracted considerable attention as potential candidates for the treatment of cholesterol-related metabolic and intractable diseases. We have advocated the use of β-CD-threaded acid-degradable polyrotaxanes (PRXs) as intracellular delivery carriers for β-CDs. As unmodified PRXs are insoluble in aqueous solutions, chemical modification of PRXs is an essential process to improve their solubility and impart novel functionalities. In this study, we investigated the effect of the modification of zwitterionic sulfobetaines on PRXs due to their excellent solubility, biocompatibility, and bioinert properties. Sulfobetaine-modified PRXs were synthesized by converting the tertiary amino groups of precursor 2-(N,N-dimethylamino)ethyl carbamate-modified PRXs (DMAE-PRXs) using 1,3-propanesultone. The resulting sulfobetaine-modified PRXs showed high solubility in aqueous solutions and no cytotoxicity, while their intracellular uptake levels were low. To further improve this system, we designed PRXs cografted with zwitterionic sulfobetaine and cationic DMAE groups via partial betainization of the DMAE groups. Consequently, the interaction with proteins, intracellular uptake levels, and liver accumulation of partly betainized PRXs were found to be higher than those of completely betainized PRXs. Additionally, partly betainized PRXs showed no toxicity in vitro or in vivo despite the presence of residual cationic DMAE groups. Furthermore, partly betainized PRXs ameliorated the abnormal free cholesterol accumulation in Niemann-Pick type C disease patient-derived cells at lower concentrations than β-CD derivatives and previously designed PRXs. Overall, the cografting of sulfobetaines and amines on PRXs is a promising chemical modification for therapeutic applications due to the high cholesterol-reducing ability and biocompatibility of such modified PRXs. In addition, modification with both zwitterionic and cationic groups can be used for the design of various polymeric materials exhibiting both bioinert and bioactive characteristics.

A versatile method for multiclass determination of β-lactam drugs in urine by solid-phase extraction followed by HILIC-UV

A method for multiclass determination of β-lactam antibiotics in human urine by solid-phase extraction (SPE) prior to quantification by hydrophilic interaction liquid chromatography (HILIC) was developed. Four cephalosporins, one carbapenem and four penicillins were selected among the most prescribed β-lactam drugs. A HILIC column – silica-linked zwitterionic sulfobetaine groups – proved to be valuable for analysis of these three classes of highly hydrophilic compounds, with suitable capacity factors, peak shape and resolution gained by proper selection of the chromatographic conditions. Sample extraction has been performed on Strata™-X. The quick SPE procedure entirely developed in urine successfully combined sample clean-up, avoiding protein precipitation before extraction, with recovery higher than 66% (interday RSD < 15%, n = 5), and method quantification limits in urine in the range 1–4 µg mL−1. Selectivity has been proven on blank urine samples, also in presence of several non-target pharmaceuticals, and the method was applied to the analysis of samples from four patients under β-lactams therapy.

Water splitting-assisted electrocatalysis based on dendrimer-encapsulated Au nanoparticles for perspiration glucose analysis

• Dendrimer-encapsulated Au nanoparticles (Au DENs) for wearable perspiration glucose analysis was achieved based on water splitting-assisted electrocatalysis. • Smaller Au DENs were found to be more electrocatalytically active toward glucose oxidation which ensures highly sensitive detection of trace glucose in perspiration. • Zwitterionically terminated dendrimer provides an anti-fouling coating of the electrocatalyst for highly selective and durable glucose monitoring. Here, we report the use of dendrimer-encapsulated Au nanoparticles (Au DENs) terminated with zwitterionic groups (G4-NH 2 -PS(Au)) for nonenzymatic perspiration glucose analysis based on water splitting-assisted electrocatalysis (WSE). The Au DENs with controllable sizes are prepared and characterized, and their electrocatalytic activities towards nonenzymatic glucose oxidation are investigated. It is found that the Au DENs with a smaller diameter (1.3 ± 0.5 nm) show higher electrocatalytic activity than larger Au DENs do (1.7 ± 0.7 nm and 2.8 ± 1.4 nm), which leads to a sensitivity of 414 μA mM −1 cm −2 for glucose detection and a detection limit of 4.9 μM. The Au DENs terminated with zwitterionic groups also exhibit acceptable selectivity, reproducibility, and long-time stability for glucose sensing in artificial perspiration samples. The sensor is then used for wearable perspiration glucose monitoring, and the results show a correlation between perspiration glucose and blood glucose.

Zwitterionic Bifunctional Layer for Reversible Zn Anode

A Zn metal anode suffers from severe dendrite issues and passive byproducts, which restrict the practical application of Zn-ion batteries. Herein, a bifunctional poly zwitterionic ionic liquid (PZIL) is designed as a new ion-migration layer to suppress Zn dendrites and side reactions. On one hand, the zwitterionic functional groups on the PZIL layer guide the Zn ion distribution to regulate the deposition behavior of Zn. On the other hand, the tight bond between zwitterionic groups and water molecules can build an H2O-poor interface on the surface of the Zn anode to avoid side reactions. Based on the above two functions, a symmetrical cell with the PZIL-layer-modified Zn exhibits a stable plating/stripping performance (2600 h at 1 mA cm–2) with low reversible deposition potential (∼50 mV). The concept of a zwitterionic bifunctional layer will open up a new avenue for reversible anodes for Zn-ion batteries as well as other battery systems.

Influence of zwitterionic structure design on mixed matrix membrane stability, hydrophilicity, and fouling resistance: A computational study

Zwitterion-based mixed matrix membranes (MMMs) with designed characteristics of enhanced water flux, selectivity, and fouling mitigation have emerged as a new class of advanced membranes for oilsands process-affected wastewater (OSPW) treatment. Zwitterions (ZW) characterized by super-hydrophilicity and excellent fouling resistance have gained increasing attention in membrane modification research. In general, zwitterion properties are determined by the chemistry and structural properties of its constituents, including the polymer backbone, charged moieties, spacers, as well as molecular configuration. This study used molecular dynamics simulation (MDS) to investigate the effects of polymer backbone (PB), spacer length (SL), and spacer chemistry (SC) on ZW-based MMM properties such as stability, hydrophilicity, and oil-antifouling potentiality. Membrane performance was also assessed at high temperatures (50, 70, and 90 °C. The results suggest PB, SL, and SC all influence the resultant MMM performance, with SL being the most impactful structural parameter on stability and hydrophilicity. Variation of SL was suspected to alter the ionic association and partial charges of zwitterionic moieties, which affect their ability to interact with the polymer network and water molecules. Spacer chemistry (i.e., hydroxyl (-OH) groups) can initiate self-association between zwitterionic charged groups having short SL, lessening their inter-molecular networking ability. However, for ZWs with long SL, the presence of hydroxyl groups on the spacer can result in the formation of hydrogen bonds and/or electrostatic interactions with other ZW molecules and polyvinylidene difluoride (PVDF) polymer chains or water molecules, improving membrane stability and hydrophilicity. High temperatures reduced membrane stability but to a lesser extent for MMMs compared to unmodified PVDF membrane. While temperature greatly influenced membrane hydrophilicity, the impacts were membrane-specific. The oil-fouling propensity of pristine PVDF membrane increased with temperature but of MMMs appeared stable across the temperature range studied.

Zwitterionic Block Copolymers for the Synthesis and Stabilization of Perovskite Nanocrystals.

Traditional hot injection methods for the preparation of cesium lead halide perovskite nanocrystals (CsPbX3 PNCs, where X=Cl, Br, or I) rely on small molecule surfactants to produce PNCs with cube, plate, or rod-like morphologies. Here, we describe a new method whereby zwitterionic block copolymers are employed as macromolecular ligands in PNC synthesis, affording PNCs with excellent colloidal stability, high photoluminescence quantum yield, and in some cases distinctly non-cubic shapes. The block copolymers used in this study - composed of a poly(n-butyl methacrylate) hydrophobic block and zwitterionic methacrylate hydrophilic blocks - dissolve in useful solvents for PNC growth despite containing large mole percentages of zwitterionic groups. PNCs prepared with block copolymer ligands were found to disperse and retain their fluorescence in a range of polar organic solvents and were amenable to direct integration into optically transparent nanocomposite thin films with high PNC content.

Regulation of Gramicidin Channel Function Solely by Changes in Lipid Intrinsic Curvature.

Membrane protein function is regulated by the lipid bilayer composition. In many cases the changes in function correlate with changes in the lipid intrinsic curvature (c0), and c0 is considered a determinant of protein function. Yet, water-soluble amphiphiles that cause either negative or positive changes in curvature have similar effects on membrane protein function, showing that changes in lipid bilayer properties other than c0 are important—and may be dominant. To further investigate the mechanisms underlying the bilayer regulation of protein function, we examined how maneuvers that alter phospholipid head groups effective “size”—and thereby c0—alter gramicidin (gA) channel function. Using dioleoylphospholipids and planar bilayers, we varied the head groups’ physical volume and the electrostatic repulsion among head groups (and thus their effective size). When 1,2-dioleyol-sn-glycero-3-phosphocholine (DOPC), was replaced by 1,2-dioleyol-sn-glycero-3-phosphoethanolamine (DOPE) with a smaller head group (causing a more negative c0), the channel lifetime (τ) is decreased. When the pH of the solution bathing a 1,2-dioleyol-sn-glycero-3-phosphoserine (DOPS) bilayer is decreased from 7 to 3 (causing decreased head group repulsion and a more negative c0), τ is decreased. When some DOPS head groups are replaced by zwitterionic head groups, τ is similarly decreased. These effects do not depend on the sign of the change in surface charge. In DOPE:DOPC (3:1) bilayers, pH changes from 5→9 to 5→0 (both increasing head group electrostatic repulsion, thereby causing a less negative c0) both increase τ. Nor do the effects depend on the use of planar, hydrocarbon-containing bilayers, as similar changes were observed in hydrocarbon-free lipid vesicles. Altering the interactions among phospholipid head groups may alter also other bilayer properties such as thickness or elastic moduli. Such changes could be excluded using capacitance measurements and single channel measurements on gA channels of different lengths. We conclude that changes gA channel function caused by changes in head group effective size can be predicted from the expected changes in c0.

Effect of Interfacial Properties on Impedimetric Biosensing of the Sialylation Process with a Biantennary N-Glycan-Based Monolayer.

Sensing enzymatic sialylation provides new tools for the evaluation of pathological events and pathogen invasion. Enzymatic sialylation is usually monitored via fluorescence or metabolic labeling, which requires relatively large amounts of the glycan substrate with limited availability. Using a label-free biosensor requires smaller quantities of substrates because the interactions induce measurable changes to an interface, which can be translated into a signal. The downside of label-free biosensors is that they are very sensitive to changes at the interface, and the properties of the surface layer can play a major role. Electrochemical impedance spectroscopy was used here to follow the enzymatic sialylation of a biantennary N-glycan acceptor in mixed monolayers. The surfaces contained either neutral, positively or negatively charged, or zwitterionic functional groups. The systems were characterized by contact potential difference, ellipsometry, and contact angle analyses. We found that the characteristics of the mixed monolayer have a profound effect on the biosensing of the enzymatic sialylation. Positively charged layers were found to adsorb the enzyme under the reaction conditions. Negatively charged and zwitterionic surfaces were nonresponsive to enzymatic sialylation. Only the neutral mixed monolayers provided signals that were related directly to enzymatic sialylation. This work demonstrates the importance of appropriate interface properties for monitoring enzymatic sialylation processes.

Sol-gel-derived hard coatings from tetraethoxysilane and organoalkoxysilanes bearing zwitterionic and isothiazolinone groups and their antifouling behaviors.

Current environmentally friendly marine antifouling (AF) coatings are mainly polymeric with a relatively low hardness. Hard sol-gel-derived AF coatings for underwater robot-cleaning are seldom used. In this work, two new organoalkoxysilanes, i.e., (N-methoxyacylethyl)-3-aminopropyltriethoxysilane and 2-(2-hydroxy-3-(3-(trimethoxysilyl)propoxy)propyl)benzo[d]isothiazol-3(2H)-one, were synthesized by a facile method. These two precursors were used with tetraethoxysilane (TEOS) to produce three series of hybrid AF coatings with zwitterionic group (Z-χ), antibacterial group (1,2-benzisothiazolin-3-one) (A-χ) and zwitterionic and antibacterial groups (S-χ) by a sol-gel process. The hardness of the coatings was measured using a pencil hardness tester and the AF behaviors of the coatings were examined by laboratory and field assays. A pencil hardness up to 5 H was achieved and slight deterioration was observed after 9 months of immersion in artificial seawater for the A-χ and S-χ coatings at a sufficiently high TEOS content. A synergistic effect between the zwitterion and antimicrobial agents existed but was not obvious. A higher TEOS content led to a higher hardness and better AF performance regardless of the type of AF group. Even with the same biofilm formation after field assay, coatings with a higher TEOS content exhibited a better resistance to mussel settlement.

Zwitterionic surface chemistry enhances detachment of bacteria under shear.

The ubiquitous nature of microorganisms, especially of biofilm-forming bacteria, makes biofouling a prevalent challenge in many settings, including medical and industrial environments immersed in liquid and subjected to shear forces. Recent studies have shown that zwitterionic groups are effective in suppressing bacteria and protein adhesion as well as biofilm growth. However, the effect of zwitterionic groups on the removal of surface-bound bacteria has not been extensively studied. Here we present a microfluidic approach to evaluate the effectiveness in facilitating bacteria detachment by shear of an antifouling surface treatment using (3-(dimethyl;(3-trimethoxysilyl)propyl)ammonia propane-1-sulfonate), a sulfobetaine silane (SBS). Control studies show that SBS-functionalized surfaces greatly increase protein (bovine serum albumin) removal upon rinsing. On the same surfaces, enhanced bacteria (Pseudomonas aeruginosa) removal is observed under shear. To quantify this enhancement a microfluidic shear device is employed to investigate how SBS-functionalized surfaces promote bacteria detachment under shear. By using a microfluidic channel with five shear zones, we compare the removal of bacteria from zwitterionic and glass surfaces under different shear rates. At times of 15 min, 30 min, and 60 min, bacteria adhesion on SBS-functionalized surfaces is reduced relative to the control surface (glass) under quiescent conditions. However, surface-associated bacteria on the SBS-functionalized glass and control show similar percentages of live cells, suggesting minimal intrinsic biocidal effect from the SBS-functionalized surface. Notably, when exposed to shear rates ranging from 104 to 105 s-1, significantly fewer bacteria remain on the SBS-functionalized surfaces. These results demonstrate the potential of zwitterionic sulfobetaine as effective antifouling coatings that facilitate the removal of bacteria under shear.

Preparation of anti-fouling zwitterionic nanofiltration membrane with tunable surface charge

Anti-fouling property is of vital significance and remains a challenge in the membrane separation field. In this work, N-diethylethylenediamine (DEEDA) was incorporated into the polyamide matrix first. Then, an anti-fouling zwitterionic nanofiltration membrane with tunable surface charge was fabricated by the grafting of p-xylylene dichloride (XDC) on the membrane surface. The resulting nanofiltration membrane possessed zwitterionic groups of positively charged N+ and negatively charged COO-. Meanwhile, the surface charge could be tuned precisely by the concentration of XDC. A neutrally charged nanofiltration membrane was obtained when the concentration of XDC was 1.0 ​wt% and the preparing membrane showed permeance of 9.1 ​L·m-2·h-1·bar-1 with high rejection of CaCl2 (90.8%) and Na2SO4 (91.3%) at pH ​= ​6.5. This membrane exhibited excellent anti-fouling properties towards not only negatively charged bovine serum albumin but also positively charged lysozyme. The optimum membrane, PA-XDC-1.0, had flux recovery rates of 95.0% and 94.0% for bovine serum albumin and lysozyme, respectively, which was higher than those of PA-DEEDA-0 (86.1% and 80.7%). This work offered a facile way to fabricate an anti-fouling zwitterionic nanofiltration membrane with tunable surface charge, which had wide applications in water purification.

Zwitterionic Dipicolinic Acid-Based Tracers for Reservoir Surveillance Application

Chemical tracing within oil reservoirs enables the determination of fluid allocation and interwell flow characteristics for improving injection fluid sweep efficiency and reservoir management, and thus novel instrument-readable, independently distinguishable tracers with ultralow sensitivity and detectability are highly desired. We present a series of dipicolinic acid (DPA)-based molecules as a new class of water tracers for reservoir surveillance applications, demonstrating the design and synthesis of three novel DPA-based molecules confirmed and characterized via NMR and mass spectroscopy. Further installation of zwitterionic functional groups onto the structure of these DPA-based tracer candidates leads to marked reductions in their dynamic rock retention, as demonstrated via core flooding experiments. From an optical detection standpoint, all synthesized DPA derivatives exhibit strong chelation with rare earth ions such as terbium (Tb3+) and emit long-lived fluorescence characteristic of lanthanide chelates, making them detectable using time-resolved fluorescence spectroscopy down to the parts-per-trillion (ppt) level. The time-resolution component is critical for their application as water tracers in reservoir fluids, enabling bypassing of background fluorescence from crude oil and other interferents present in brine. Results show that the stepwise derivatization of native DPA and its analogues generates a suite of molecular structures that can be effectively separated and identified using high-performance liquid chromatography (HPLC). Studies on long-term thermal stability at 100 °C and orthogonal detection by optical and chromatographic methods have demonstrated that the newly developed DPA-based ligands described herein have great potential to serve as highly traceable interwell oilfield tracers.

Fabrication of a novel hybrid poly(amide-co-arylate)/MOF thin film membranes for organic solvent nanofiltration: optimization of membrane separation performance

Introducing a high separation performance membrane is one of the most essential requirements of an efficient polymeric membrane-based technology. In this regard, we employed different weight ratio of cardo-structured 9,9-bis(4-hydroxyphenyl)fluorene monomer (BHPF) to fabricate the novel polyacrylonitrile (PAN)-based poly(amide- co -arylate) thin film composite membranes through interfacial polymerization for use in organic solvent nanofiltration (OSN) field. In addition, the prepared poly(amide- co -arylate) thin films were filled with different content of porous metal organic framework (MOF) nanoparticles in order to attain high permeable polymeric membranes. Besides, the organically modified MOF nanoparticles and poly[2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide-co-poly(2-hydroxyethyl methacrylate) (PMSA- co -PHEMA) copolymer nanoparticles containing zwitterionic groups were synthesized for further investigation. It was found that the designed poly(amide- co -arylate) thin film composite membrane fabricated by equal ratios of m -phenylenediamine (MPD) and BHPF monomers showed the highest tetrahydrofuran (THF) flux value compared with other thin film composite (TFC) membranes. Moreover, incorporating 0.003 wt% of MOF nanoparticles within this poly(amide- co -acrylate) thin film led to a good retention up to 90, 88 and 98% for bromophenol blue (BPB), acid blue 7 (ACB) and methyl green (MG) dyes, respectively. Furthermore, this thin film nanocomposite (TFN) membrane displayed an acceptable pure THF flux as high as 2 Lm-2h-1bar-1 at 10 bar. Also, evaluating long-term stability application of this TFN membranes demonstrated a slight reduction in THF flux, indicating that this membrane is highly efficient for use in the OSN field. • The novel hybrid PAN-based poly(amide- co -arylate)/MOF thin film membranes were fabricated. • The modified MOF nanoparticles and PMSA- co -PHEMA copolymer nanoparticles comprising zwitterionic groups were synthesized. • The TFN membrane containing 0.003 wt% MOF exhibited the pure THF flux around 2 Lm-2h-1bar-1. • The high rejection value around 90, 88 and 98% was observed for BPB, ACB and MG dyes, respectively.

Zwitterionic hydrogel-coated cotton fabrics with underwater superoleophobic, self-healing and anti-fouling performances for oil-water separation

• Zwitterionic hydrogel with self-healing property was coated on the cotton fabric. • The coated fabric exhibited anti-fouling and underwater superoleophobic properties. • The coated fabric had superior oil/water separation property under gravity drive. • The coated fabric displayed the outstanding cyclic stability and reusability. Oil-water separation technology has attracted widespread attention, due to the increasingly serious oil pollution. In this work, novel poly(sulfobetaine methacrylate- co -2-hydroxyethyl acrylate)/poly(vinyl alcohol)/borax (PSBMA/PVA/Borax) hydrogels were prepared. Then, the related gel-coated cotton fabrics for oil-water separation were successfully developed in a facile route. The results presented the as-prepared zwitterionic hydrogels had outstanding self-healing ability, low swelling ratio, and satisfactory mechanical properties because of multiple interactions in the hydrogel’s network. As expected, the zwitterionic hydrogel-coated cotton fabric was imparted with excellent underwater superoleophobicity and outstanding anti-fouling ability due to the existence of zwitterionic groups on the surface. The underwater oil contact angle of the as-prepared fabric was approximately 160° towards a series of oils. Meanwhile, oily contaminations on the zwitterionic hydrogel-coated fabric surface can be rapidly removed just by water immersion. Most importantly, the zwitterionic hydrogel-coated fabric exhibited excellent oil-water separation efficiency (approximately 99%) and water flux (about 15, 181 L -1 ·m −2 ·h −1 ) even after 50 successive cycles. Additionally, the zwitterionic hydrogel-coated fabric also presented remarkable chemical and mechanical stabilities in harsh conditions. The as-prepared cotton fabric presents a great application prospect in oily wastewater treatment.

Zwitterionic Covalent Organic Frameworks: Attractive Porous Host for Gas Separation and Anhydrous Proton Conduction

Ionic covalent organic frameworks (COFs) consisting of an anionic or cationic skeleton and corresponding counterions have demonstrated great potential in many application fields such as ion conduction, molecular separation, and catalysis. However, arranging anionic and cationic groups into the same COF to form zwitterionic materials is still unexplored. Herein we design the synthesis of three zwitterionic COFs as attractive porous hosts for SO2/CO2 separation and anhydrous proton conduction. The separated cationic and anionic groups in zwitterionic COFs' channels can act as two different polar sites for SO2 adsorption, allowing zwitterionic COFs to achieve a high SO2 adsorption capacity (216 mL/g, 298 K) and impressive SO2/CO2 selectivity (118, 298 K). Furthermore, after loading with triazole/imidazole, the zwitterionic groups in COFs' channels can induce complete proton carrier deprotonation, producing more freely migrating protons. The free protons migrate along a continuous hydrogen-bonding network in zwitterionic COFs' channels, leading to outstanding anhydrous proton conductivity up to 4.38 × 10-2 S/cm, which is much higher than other N-heterocyclic-doped porous materials under anhydrous conditions. Proton dissociation energy calculations combined with frequency-dependent dielectric analysis give insight into the role of zwitterionic COFs for proton conductivity. Our work provides the possibility to design well-defined zwitterionic frameworks for gas separation and ion conduction.

Construction of antifouling zwitterionic membranes by facile multi-step integration method

Membrane fouling during the use of separation membrane has always been the main reason for the degradation of membrane performance. The traditional solution is complicated and inefficient, so we proposed multi-step integration method to prepare antifouling zwitterionic poly(aryl ether sulfone) (PAES-Z-x) ultrafiltration (UF) membrane with higher efficiency. We designed and synthesized a bisphenol precursor containing tertiary amine groups, which could provide reactive sites for grafting zwitterionic group. Afterwards, the zwitterionic modified UF membrane was prepared by graft copolymerization and non-solvent-induced phase separation (NIPS). The morphology, hydrophilicity, water flux and rejection of the PAES-Z-x membrane could be optimized by tuning zwitterion content. The hydration layer formed by zwitterions effectively reduced the adsorption of proteins and endowed the membrane good antifouling properties. The resulting membrane showed the pure water flux increased (up to 311 L m−2h−1 bar−1), high bovine serum albumin (BSA) rejection (97%) and good water flux recovery ratio (FRR) (82.8%). Zwitterionic antifouling PAES UF membrane prepared by a simple and effective method provided a new direction for improving PAES UF membrane’s antifouling performance.

Low Fouling Polysulfobetaines with Variable Hydrophobic Content.

Amphiphilic polymer coatings combining hydrophilic elements, in particular zwitterionic groups, and hydrophobic elements comprise a promising strategy to decrease biofouling. However, the influence of the content of the hydrophobic component in zwitterionic coatings on the interfacial molecular reorganization dynamics and the anti-fouling performance is not well understood. Therefore, coatings of amphiphilic copolymers of sulfobetaine methacrylate 3-[N-2'-(methacryloyloxy)ethyl-N,N-dimethyl]-ammonio propane-1-sulfonate (SPE) are prepared which contain increasing amounts of hydrophobic n-butyl methacrylate (BMA). Their fouling resistance is compared to that of their homopolymers PSPE and PBMA. The photo-crosslinked coatings form hydrogel films with a hydrophilic surface. Fouling by the proteins fibrinogen and lysozyme as well as by the diatom Navicula perminuta and the green algae Ulva linza is assessed in laboratory assays. While biofouling is strongly reduced by all zwitterionic coatings, the best fouling resistance is obtained for the amphiphilic copolymers. Also in preliminary field tests, the anti-fouling performance of the amphiphilic copolymer films is superior to that of both homopolymers. When the coatings are exposed to a marine environment, the reduced susceptibility to silt incorporation, in particular compared to the most hydrophilic polyzwitterion PSPE, likely contributes to the improved fouling resistance.

Intensification of mass transfer for zwitterionic amine monomers in interfacial polymerization to fabricate monovalent salt/antibiotics separation membrane

Zwitterionic groups are conducive to improve the antifouling performance and water permeability of nanofiltration membranes because of the excellent hydrophilicity and charged property. However, the transport of zwitterionic monomers during interfacial polymerization process is much slower than the reaction, leading to form many defects in the separation layer. In this study, phase transfer catalysts were used to intensify the interfacial mass transfer of zwitterionic amine monomers for fabricating polyamide thin-film composite nanofiltration membranes. The transport process was explored by measuring the diffusion kinetics of monomers to regulate the structures and properties of zwitterionic membranes. Consequently, low concentration of N-aminoethyl piperazine propane sulfonate (AEPPS) as aqueous monomer could be used to prepare membranes with excellent nanofiltration performance. When the concentration of AEPPS was as low as 1 w/v%, the as-prepared zwitterionic membrane possessed a pure water flux of 10.6 L m−2 h−1 bar−1 with a high erythromycin retention of 91.7% and a low NaCl retention of 7.3%, which exhibited great application potential in the separation of monovalent salt/antibiotics. Moreover, the flux recovery ratio of the zwitterionic membrane was still maintained at ∼96.5% after undergoing twice fouling-rinse experiments of bovine serum albumin, exhibiting exceptional antifouling performance.

Constructing High-Recognition Protein-Imprinted Materials Using "Specially Designed" Block Macromolecular Chains as Functional Monomers and Crosslinkers.

The use of a macromolecularly functional monomer and crosslinker (MFM) to stabilize and imprint a template protein is a new method to construct high-recognition protein-imprinted materials. In this study, for the first time, a "specially designed" block MFM with both "functional capability" and "crosslinking capability" segments was synthesized via reversible addition-fragmentation chain-transfer polymerization and used to fabricate bovine serum albumin (BSA)-imprinted microspheres (SiO2@MPS@MIPs-MFM) by the surface imprinting strategy. Results from circular dichroic spectrum experiments reflected that the block MFM could maintain the natural form of BSA, whereas its corresponding and equivalent micromolecularly functional monomer (MIM) seriously destroyed the secondary structure of proteins. Batch rebinding experiments showed that the maximum adsorption capacity and imprinting factor of SiO2@MPS@MIPs-MFM reached 314.9 mg g-1 and 4.02, which were significantly superior to that of MIM-based imprinted materials. In addition, since the crosslinking capability segments in block MFM involved zwitterionic functional groups with a protein-repelling effect, SiO2@MPS@MIPs-MFM showed better specific rebinding ability than the imprinted material prepared by MFM without this component. Besides, scanning electron microscopy and transmission electron microscopy images showed that the shell thickness of SiO2@MPS@MIPs-MFM was approximately 15 nm, and such a thin imprinted layer ensured its rapid adsorption equilibrium (120 min). As a result, SiO2@MPS@MIPs-MFM revealed fantastic selectivity and recognition ability in a mixed protein solution and could efficiently extract BSA from biological samples of bovine calf serum. The proposal of block MFM enriched the options and designability of monomers in protein imprinting technology, thereby laying a foundation for developing high-performance protein-imprinted materials.

Surface-Modifying Effect of Zwitterionic Polyurethane Oligomers Complexed with Metal Ions on Blood Compatibility.

To prevent unsolved problems of medical devices, we hypothesized that combinatorial effects of zwitterionic functional group and anti-bacterial metal ions can reduce effectively the thrombosis and bacterial infection of polymeric biomaterials. In this research, we designed a novel series of zwitterionic polyurethane (zPU) additives to impart anti-thrombotic properties to a polyvinyl chloride (PVC) matrix. We have synthesized zPUs by combination of various components and zPUs complexed with metal ions. Zwitterion group was prepared by reaction with 1,3-propane sultone and Nmethyldiethanolamine and metal ions were incorporated into sulfobetaine chains via molecular complexation. These zPU additives were characterized using FT-IR, 1H-NMR, elemental analysis, and thermal analysis. The PVC film blended with zPU additives were prepared by utilizing a solvent casting and hot melting process. Water contact angle demonstrated that the introduction of zwitterion group has improved hydrophilicity of polyurethanes dramatically. Protein adsorption test resulted in improved anti-fouling effects dependent on additive concentration and decreases in their effects by metal complexation. Platelet adhesion test revealed anti-fouling effects by additive blending but not significant as compared to protein resistance results. With further studies, the synthesized zPUs and zPUs complexed with metal ions are expected to be used as good biomaterials in biomedical fields. Based on our results, we can carefully estimate that the enhanced anti-fouling effect contributed to reduced platelet adhesion. Schematic explanation of the effect of zwitterionic polyurethane additives for blood-compatible and anti-bacterial bulk modification.