Zwitterionic Functionality Research Articles

Thermally stable strongly fluorescent multi-stimuli responsive carbazole zwitterionic fluorophores: Alkyl chain length dependent thermofluorochromism and latent fingerprinting

Carbazole-picoline based π-conjugated zwitterionic fluorophores, (E)-3-(4-(4-(9H-carbazol-9-yl)styryl)pyridin-1-ium-1-yl)propane-1-sulfonate (Cz-PS) and (E)-4-(4-(4-(9H-carbazol-9-yl)styryl)pyridin-1-ium-1-yl)butane-1-sulfonate (Cz-BS) were synthesized and investigated the stimuli-responsive solid-state fluorescence properties. Cz-PS and Cz-BS displayed enhanced fluorescence in the solid-state (555 and 542 nm) with the quantum yield (Φf) of 32.9 and 28.5 %, respectively. Thermogravimetric analysis (TGA) indicated good thermal stability up to 300 °C for both Cz-PS and Cz-BS. Single crystal structural analysis of Cz-BS confirmed twisted molecular conformation and supramolecular interactions induced network structure, which lead to increase of solid-state fluorescence. Cz-BS showed mechanical stimuli-induced reversible/self-reversible fluorescence switching between two fluorescence states whereas Cz-PS did not show mechanofluorochromism. But both Cz-PS and Cz-BS showed acid/base dependent on–off reversible fluorescence switching in solution as well as solid-state. Further, both compounds also displayed reversible thermofluorochromism by heating and cooling. The yellow fluorescence of Cz-PS and Cz-BS was transformed to orange upon heating at 110 °C and cooling reversed the fluorescence to initial state. The good thermal stability and enhanced solid-state fluorescence of Cz-PS and Cz-BS were utilized for latent fingerprinting (LFP) application on various solid substrate. Particularly, LFP images of Cz-BS showed finger marks with well-defined features. Thus, integrating zwitterionic functionality produced strong solid-state fluorescence with multi-functional applications.

Intramolecular Electrostatic Interactions Regulate Reactivity of Zwitterionic Functionalities in Amphiphilic Assemblies

AbstractThe consequences of intramolecular ionic interactions in determining the reactivity of functional groups are of interest because they provide insights into how nature deploys seemingly reactive functionalities to be rather ubiquitous. Of specific interest are the quaternary ammonium ions in lipids. In this work, we investigate the effect of intramolecular electrostatic interactions in zwitterionic functionalities by judiciously incorporating them as leaving groups at the α‐position of α,β‐unsaturated ester‐based lipid head groups. We find that electrostatic stabilization indeed plays a critical role in both the reaction kinetics with nucleophiles and the thermodynamics of lipid formation. We further leverage these findings to fabricate both triggerable assembly and disassembly of liposomal supramolecular assemblies in the presence of nucleophiles.

Intramolecular Electrostatic Interactions Regulate Reactivity of Zwitterionic Functionalities in Amphiphilic Assemblies.

The consequences of intramolecular ionic interactions in determining the reactivity of functional groups are of interest because they provide insights into how nature deploys seemingly reactive functionalities to be rather ubiquitous. Of specific interest are the quaternary ammonium ions in lipids. In this work, we investigate the effect of intramolecular electrostatic interactions in zwitterionic functionalities by judiciously incorporating them as leaving groups at the α-position of α,β-unsaturated ester-based lipid head groups. We find that electrostatic stabilization indeed plays a critical role in both the reaction kinetics with nucleophiles and the thermodynamics of lipid formation. We further leverage these findings to fabricate both triggerable assembly and disassembly of liposomal supramolecular assemblies in the presence of nucleophiles.

Zwitterionic functionalization of polysaccharide gum by graft copolymerization to develop 3-D network materials for anticancer drug delivery applications

Herein, functionalization of polysaccharide gum has been carried out to develop network copolymeric materials for use in sustained anticancer drug delivery. Grafting reaction of poly[2-(methacryloyloxy)ethyl] dimethyl-(3-sulfopropyl)ammonium hydroxide (MEDSAH) onto sterculia gum has been done in the presence of crosslinker. Copolymeric materials were characterized by scanning electron micrographs (SEMs), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), 13C-nuclear magnetic resonance (NMR), and thermogravimetric analysis (TGA). SEM, AFM and XRD displayed heterogeneous morphology with a rough surfaces of amorphous copolymeric materials. Peaks at 173.822 ppm (carbonyl carbon) and at 60.653 ppm (methylene carbon attached to a quaternary ammonium group) confirmed the addition of poly(MEDSAH) during the grafting reaction. Mesh size in network hydrogel was found between 14.54 nm to 36.32 nm. Sustained release of doxorubicin was found with non-Fickian diffusion and was best demonstrated by the kinetic model Hixson Crowell. The biocompatibility of material was revealed in a haemolytic index (1.74 ± 0.26%) less than two percent during the copolymer-blood interaction. The material exhibited antioxidant and mucoadhesion properties. Free radical scavenging ability of copolymers was 49.41 ± 0.97% in 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay of the antioxidant test. These properties of copolymeric hydrogels demonstrated their suitability for use in sustained drug delivery systems for cancer chemotherapy.

Relationships between Water's Structure and Solute Affinity at Polypeptoid Brush Surfaces.

Excellent antifouling surfaces are generally thought to create a tightly bound layer of water that resists solute adsorption, and highly hydrophilic surfaces such as those with zwitterionic functionalities are of significant current interest as antifoulant strategies. However, despite significant proofs-of-concept, we still lack a fundamental understanding of how the nanoscopic structure of this hydration layer translates to reduced fouling, how surface chemistry can be tuned to achieve antifouling through hydration water, and why, in particular, zwitterionic surfaces seem so promising. Here, we use molecular dynamics simulations and free energy calculations to investigate the molecular relationships among surface chemistry, hydration water structure, and surface-solute affinity across a variety of surface-decorated chemistries. Specifically, we consider polypeptoid-decorated surfaces that display well-known experimental antifouling capabilities and that can be synthesized sequence specifically, with precise backbone positioning of, e.g., charged groups. Through simulations, we calculate the affinities of a range of small solutes to polypeptoid brush surfaces of varied side-chain chemistries. We then demonstrate that measures of the structure of surface hydration water in response to a particular surface chemistry signal solute-surface affinity; specifically, we find that zwitterionic chemistries produce solute-surface repulsion through highly coordinated hydration water while suppressing tetrahedral structuring around the solute, in contrast to uncharged surfaces that show solute-surface affinity. Based on the relationship of this structural perturbation to the affinity of small-molecule solutes, we propose a molecular mechanism by which zwitterionic surface chemistries enhance solute repulsion, with broader implications for the design of antifouling surfaces.

Fabrication of multifunction-integrated adsorbent based on zwitterion functionalized cellulose with high adsorption performance for anionic/cationic dyes and heavy metal ions

A multifunction-integrated adsorbent based on zwitterion functionalized cellulose (MCC@PGMA-IAA) was synthesized by surface grafting polymerization and then modification with polyethyleneimine and sodium chloroacetate in turn. The adsorbent exhibited high functional group contents, switchable surface charge and chelating structure of iminoacetic acid. With the methylene blue, azophloxine, Ni(II) and Cr(VI) as the models of cationic/anionic dyes and heavy metal ions, batch experiments were conducted. The material showed strong adsorption abilities for dyes and heavy metal ions, with maximum adsorption capacities up to 440.5 mg/g, 320.5 mg/g, 59.3 mg/g, and 127.9 mg/g for methylene blue, azophloxine, Ni(II) and Cr(VI), respectively. Especially, the adsorption capacities of methylene blue and Ni(II) after zwitterionic functionalization increased by 50 times and 95.5% than those after polyethyleneimine modification. The adsorption equilibria were achieved within 10–120 min, and the adsorbent exhibited excellent removal efficiency. Furthermore, the adsorbed pollutants were conveniently desorbed by low concentration of HCl or NaOH solution, and the adsorbent had good reusability. Mechanism studies proved that electrostatic attraction and chelation were main driving forces. These results showed that MCC@PGMA-IAA had the characteristics of extensive sources, simple preparation and multifunctional integration, which was poised to develop as universal adsorbent for removing heavy metal ions and dyes.

New Zwitterionic Imidazolones with Enhanced Water Solubility and Bioavailability: Synthesis, Anticancer Activity, and Molecular Docking

Finding an effective anticancer drug to combat cancer cell resistance remains a challenge. Herein, we synthesized a new series of imidazolone derivatives 4a–4i and assessed their anticancer activities against liver cancer cells (Hep3B), Hela cells, and normal LX2 cells. The imidazolne derivatives were synthesized by the condensation cyclization reaction using the natural product vanillin as a starting material. Among the synthesized imidazolones are those with an alkyl sulfate moiety that are water-soluble and showed enhanced anticancer activity against the tested cancer cells. The anticancer testing results showed that compound 4d with the NO2 group at position 4 of the benzene ring was superior to the other compounds; it showed an IC50 value of 134.2 ± 4.4 µM against Hep3B cells, while compound 4h with the pyridyl moiety showed the highest cytotoxicity against Hela cells with an IC50 of 85.1 ± 2.1 µM. The anticancer activity of some imidazolones was greatly enhanced by adding to them the zwitterionic properties that made them more polar and water-soluble. DNA binding studies with compounds 4a1, 4d, and 4g indicated a docking score ranging from approximately −6.8 to −8.7 kcal/mol. This could be attributed to the outstanding interaction between the molecule and the DNA binding sites, which primarily relies on its inherent capability to establish hydrogen bonds, facilitated by the electron pair present at the oxygen atoms and the drug’s amino group. In conclusion, water-soluble imidazolone with zwitterionic functionality could be a promising tool for the development of anticancer medication. To outline the general idea and the relationships for the effect of the developed compounds under study, as well as their mechanism of action, further extensive research is also necessary.

High-performance zwitterionic membranes via an adhesive prebiotic chemistry-inspired coating strategy: A demonstration in dye/salt fractionation

Built upon the recently developed prebiotic chemistry-inspired aminomalononitrile (AMN) coating strategy, a new class of loose nanofiltration membranes (LNMs) immobilized with zwitterionic functionality was prepared, and their capacity in dye/salt fractionation was explored. The immobilization of a zwitterionic copolymer poly(sulfobetaine methacrylate-co-2-aminoethyl methacrylate hydrochloride) (PSBAE) assisted by the AMN chemistry was proven successful. The resulting membrane exhibited a dense selective layer with a more hydrophilic and nearly electroneutral surface. Although increasing the AMN/PSBAE ratio led to an enhanced membrane performance, only limited improvement was observed beyond 1:7. Comprehensive investigations of the optimal membrane MA1P7 with various feeds demonstrated that size sieving was the dominant separation mechanism, and the electrostatic interaction was minimized due to the zwitterionic nature. With a competitive water permeance of 75.3 L m−2 h−1 bar−1, the as-developed membrane shows consistently high rejection of both negative and positively charged dyes (up to 99.9%) and consistently lower rejection of salts (<10%) at different salinity levels, which means that the membrane developed here exhibited more versatility in terms of its resilience to compositional changes of the wastewater. Overall, this work explored the versatility of the AMN-based modification method in producing efficient membranes with superior molecular fractionation ability in water applications.

Triethanolamine-based zwitterionic polyester thin-film composite nanofiltration membranes with excellent fouling-resistance for efficient dye and antibiotic separation

Water pollution and scarcity caused by small organic compounds (dyes and antibiotics) have attracted considerable attention due to their potential adverse effects on ecological environment and human body. Nanofiltration membranes with high performance, such as high rejection and fouling resistance, are expected to address these challenges. Herein, a new zwitterionic triethanolamine-based (Z-TEOA) monomer is proposed for the fabrication of zwitterionic polyester thin-film composite nanofiltration (ZNF) membranes. Z-TEOA is successfully synthesized via the ring-open reaction between TEOA and 1,3-propane sultone. ZNF membranes are fabricated via the interfacial polymerization under alkaline conditions. All fabricated membranes exhibit enhanced hydrophilicity and permeability due to the introduction of the zwitterionic functionality in the thin film layers. Specifically, the optimum membrane (ZNF1.5-5) shows an ultralow water contact angle (WCA) of 20.2°, high rejections to Congo red (CR, 99.9%), methyl blue (MB, 99.7%), orange G (OG, 95.9%), and tetracycline (TC, 96.7%). The uncompromised MB rejection of the ZNF membrane after a chlorine exposure (10,000 ppm.h) indicates its excellent chlorine resistance. Furthermore, the achieved ultrahigh flux recovery ratio (FRR, 97.8%) for MB demonstrates its outstanding fouling-resistant performance. All results reveal its potential for applications in the treatment of wastewaters from textile and pharmaceutical industries.

High performance loose nanofiltration membranes with enhanced fouling-resistance by rapid covalent co-deposition of dopamine and diamine-zwitterion

Nanofiltration (NF) membranes have been extensively employed for the treatment of textile wastewater to produce clean water, due to their capability of retaining small organic molecules. In this study, zwitterionic loose nanofiltration (Z-NF) membranes have been successfully fabricated by the rapid co-deposition of dopamine and diamine-zwitterion (Z-DNMA) via covalent bonds. The fabricated Z-NF membranes show improved hydrophilicity and enhanced fouling-resistant ability due to the incorporation of the zwitterionic functionality. Following the systematic investigation on the ratio between dopamine and Z-DNMA as well as the co-deposition time, the identified optimum membrane (Z-NF3) exhibits a high pure water permeability (PWP) of 32.0 LMH bar−1 and high organic dye rejections of 99.7 % and 98.6 % for Congo red (CR) and methyl blue (MB), respectively. In addition, the fouling experiments of Z-NF3 show that the flux recovery ratios (FRRs) for the filtration of bovine serum albumin (BSA), sodium alginate (NaAlg), and CR are 99.1 %, 92.0 %, and 82.2 %, respectively, along with lower irreversible fouling ratios (Rir) and higher reversible fouling ratios (Rr) values compared to those of the control membrane. The high PWP and high rejections to organic dyes, coupled with its superior fouling-resistant performance, indicate its great potential for practical applications in the treatment of textile wastewater.

Trimethylamine N-oxide-derived zwitterionic polyamide thin-film composite nanofiltration membranes with enhanced anti-dye deposition ability for efficient dye separation and recovery

Organic dyes from textile industries are becoming the second largest pollutants in the world. In this study, inspired by the seawater fish, a new diamine monomer, N,N-bis(3-aminopropyl)methylamine N-oxide (DNMAO) with a trimethylamine N-oxide (TMAO)-derived “N+─O−” zwitterionic functionality, has been designed for the fabrication of polyamide thin-film composite (TFC) membranes to purify dye-contaminated water and recover organic dyes. The fabricated membranes show enhanced permeability and improved anti-dye-deposition performance. The optimum membrane fabricated at 0.5 wt% of DNMAO feed solution exhibits an ultrahigh pure water permeability (PWP) of 37.5 LMH bar−1, a superior Congo red (CR) rejection of 99.93%, and a low sodium chloride (NaCl) rejection of 9.3%, indicating its outstanding performance for dye/salt separation. It can also achieve the complete CR removal from a feed with a low CR concentration of 1 ppm, demonstrating its superior separation performance for the production of clean potable water. In addition, the low dye loss rate (6.22%) and high salt removal rate (85.6%) are achieved during the purification and recovery test with CR/NaCl mixtures. Furthermore, the optimum membrane possesses an excellent anti-dye-deposition performance with a flux recovery ratio (FRR) of 92.1%. All these results demonstrate its potential for applications in not only textile wastewater treatment but also organic dye purification and recovery.

Application of sub-/supercritical fluid chromatography for the fingerprinting of a complex therapeutic peptide.

The application area of supercritical fluid chromatography expanded tremendously over the last years and more polar analytes such as biomolecules have become accessible. The growing interest in biopharmaceuticals and associated regulatory requirements demand alternative analytical tools. The orthogonal nature of supercritical fluid chromatography compared to reversed-phase liquid chromatography meets these needs and makes it a useful option during research and development. In this study, we present a systematic approach for the development of a supercritical fluid chromatography method for fingerprinting of tyrothricin, a complex therapeutic peptide covering a mass range from 1200 to 1900Da. The substance was chosen due to the presence of cyclic and linear peptides and isomeric or highly similar amino acid sequences. Different column chemistries covering neutral, basic, and zwitterionic functionalities in combination with acidic, basic, and neutral additives were screened. Subsequently, Design-of-Experiments principles were utilized to perform optimization of the chromatographic parameters. The final mass spectrometry-compatible gradient method using a diol stationary phase, carbon dioxide, and a modifier consisting of methanol/water/methanesulfonic acid (100:2:0.1, v:v:v) was found to provide orthogonality and superior resolution to other methods published. Isomeric peptide compounds coeluting in reversed-phase liquid chromatography were resolved by applying the final method.

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.

A prebiotic chemistry inspired one-step functionalization of zwitterionic nanofiltration membranes for efficient molecular separation

Loose nanofiltration (LNF) membranes have shown promises in achieving efficient separation on molecular level at relatively low pressure. In this study, a zwitterionic PES/AMN/PSBAE LNF membrane was designed by co-depositing the AMN and an in-house made zwitterionic copolymer of poly(sulfobetaine methacrylate-co-2-aminoethyl methacrylate hydrochloride) (PSBAE), in which a bio-inspired molecule aminomalononitrile (AMN) with prebiotic chemistry was used to replace the commonly applied polydopamine for rapid membrane coating, significantly reducing the surface modification time from more than 20 h to less than 1 h. The AMN-based LNF, namely PES/AMN/PSBAE membrane, was demonstrated in the separation of dye/salt from synthetic textile wastewater, exhibiting superior performance with a high water permeance of 62.9 LMH bar−1 and nearly complete dye/salt fractionation, i.e., simultaneously a high rejection of all dyes tested up to 99.9% and almost complete transport of salts. Combining with material and membrane characterization, the separation performance of the membrane was evaluated, demonstrating the advantages of the prebiotic chemistry coating and zwitterionic functionality. This study provides a new and facile strategy based on the AMN chemistry for LNF membrane surface functionalization to achieve efficient molecular separation.

Molecular grafting and zwitterionization based antifouling and underwater superoleophobic PVDF membranes for oil/water separation

Effective surface modification strategies are at the core of developing efficient and antifouling membranes for a range of separation, purification, and wastewater treatment applications. The inherently hydrophobic nature of most polymeric membranes is one of the primary factors for their high fouling susceptibility. In this work, we have designed a simple and straightforward membrane modification methodology utilizing the reactive nature of polydopamine to molecularly graft short chain amino alkanes followed by zwitterionization using 1,3-propanesultone. The prepared membranes demonstrated superhydrophilicity accompanied with underwater superoleophobicity originating from the hydrophilic nature of polydopamine, aminoalkanes, and strong hydration due to zwitterionic functionality. The surface chemistry, nanostructuring, and surface roughness play an essential role in delivering required properties in the membranes. The prepared membranes showed ultrahigh BSA protein resistance and low oil droplets adhesion. The functionalized membranes showed a manifold boost in permeability for pure water and BSA solution, and separation of oil-water emulsion at high permeation rates. The antifouling nature of the membranes helped in maintaining the permeation behavior for multiple cycles with >96% flux recovery after ten consecutive cycles and excellent rejection in oil-water emulsion separation (>98%). The superwetting properties, along with high permeation, rejection, and antifouling properties, make these membranes a potential candidate for oily water separation and demonstrate the effectiveness of simple molecular level grafting and functionalization as a straightforward method for membrane modifications.

Zwitterionic cellulose as a promising sorbent for anionic and cationic dyes

This work aimed to develop zwitterionic cellulose with a versatile potential for removing anionic and cationic dyes. A grafting degree of 22% in a 3:2 ratio of the anionic and cationic groups was determined by elemental analysis. Spectroscopic characterization by carbon 13 Nuclear Magnetic Resonance (13C NMR) confirmed the zwitterionic functionalization of cellulose. Removal tests showed that zwitterionic cellulose could interact with different dyes (Congo red, Crystal violet, Mordant blue 9, Malachite green, Xylidine ponceau, and Reactive black 5), achieving from 2 to 14-fold of removal at tested conditions.

Amphiphilic Zwitterionic Acrylate/Methacrylate Copolymers for Marine Fouling-Release Coatings.

Methacrylate and acrylate monomers are popular building blocks for antifouling (AF) and fouling-release (FR) coatings to counteract marine biofouling. They are used in various combinations and often combined into amphiphilic materials. This study investigated the FR properties of amphiphilic ethylene glycol dicyclopentenyl ether acrylate (DCPEA) and the corresponding methacrylate (DCPEMA) blended with 5 wt % zwitterionic carboxybetaine acrylate (CBA) and the corresponding methacrylate (CBMA). A series of (co)polymers with different acrylate/methacrylate compositions were synthesized and tested against the attachment of the diatom Navicula perminuta and in short-term dynamic field exposure experiments. The more hydrophobic methacrylate DCPEMA homopolymer outperformed its acrylate counterpart DCPEA. Incorporated zwitterionic functionality of both CBMA and CBA imparted ultralow fouling capability in the amphiphilic polymers toward diatom attachment, whereas in the real ocean environment, only the employment of CBMA reduced marine biofouling. Moreover, it was observed that CBA-containing coatings showed different surface morphologies and roughnesses compared to the CBMA analogues. Particularly, a high impact was found when acrylic CBA was mixed with methacrylic DCPEMA. While the wettability of the coatings was comparable, investigated methacrylates in general exhibited superior fouling resistance compared to the acrylates.

Feasible and economical treatment of real hand-drawn batik/textile effluent using zwitterionic adsorbent coating: Removal performance and industrial application approach

A novel adsorbent-based coating with zwitterionic functionality (ZwitAd) was employed to treat the heavily polluted hand-drawn batik industrial effluent. The adsorbent was prepared as a coating and supported onto a cotton cloth by applying a simple preparation method based on the combined use of clay-based adsorbent, polymer-based binder, and cationic polyelectrolyte. Batik effluent which is known to have high chemical oxygen demand (COD) (412–2205 mg/L) and colour intensity (500–16900 ADMI) has undertaken treatment process using ZwitAd. The results showed a significant reduction of COD (147 mg/L), colour (128 ADMI), and pH (7.34), which complied with the standard discharge limit for industrial effluent regulations. The finding proved that ZwitAd is applicable to reduce the COD and colour intensity and stabilise the pH of water. This new innovative treatment has simultaneously improved the effluent conditions and minimised operational costs, and minimum secondary waste is generated. The proposed application of ZwitAd at an industrial scale has also been introduced as a functional industrial storage tank with a feasible and practical operation.

Glycine-modified organic polymer monolith featuring zwitterionic functionalities for hydrophilic capillary electrochromatography.

Allylglycine, a conventional amino acid derivative, possesses typical zwitterionic and hydrophilic functionalities deriving from the carboxyl and amino groups in its structure. A novel monolithic column poly(allylglycine-co-1, 3, 5-triacryloylhexahydro-1, 3, 5-triazine) (AGly-co-TAT) with powerful hydrophilic selectivity and obvious zwitterionic feature was synthesized successfully with the monomer allyglycine and the cross-linker 1, 3, 5-triacryloylhexahydro-1, 3, 5-triazine through in-situ copolymerization for capillary electrochromatography. The obtained monolithic column has good permeability. Due to the zwitterionic functional groups of allylglycine, the poly(AGly-co-TAT) monolithic column can generate a cathodic and anodic electroosmotic flow (EOF) by changing the mobile phase pH, which is beneficial to expand its application range. The separations of different series of polar analytes, thioureas, xanthines, phenols, peptides and acidic compounds are achieved on this hydrophilic monolithic column due to the powerful hydrophilic, electrostatic and hydrogen bond interactions. Using this monolithic column, hydrophilic separations are achieved even at a lower level of 50% organic solvent. The separation efficiency up to 1.41×105 N m-1 and 1.19×105 N m-1 is achieved for the separation of theophylline and phenol, respectively. For a real sample, cytochrome C digestion, the monolithic column shows good separation performance, which offers the potential application of the monolithic column on proteomics study.

Studies of zwitterionic sulfobetaine functionalized polypropylene surface with or without polyethylene glycol spacer: surface characterization, antibacterial adhesion, and platelet compatibility evaluation

Microbial adhesion reduction as well as platelet compatibility improvement have been suggested as the key requirements for developing blood-contacting synthetic biomaterials. Surface grafting of hydrophilic polyethylene glycol chains or alkyl chains with zwitterionic terminal ends has been proposed for reducing microbial or platelet adhesion. Nonetheless, none has been reported to incorporate both polyethylene glycol and zwitterionic terminal functionality on the same surface-grafted alkyl chain. In this investigation, a novel surface modification scheme was reported for grafting zwitterionic alkyl chains with or without polyethylene glycol as the spacer. It was noted the bacterial adhesion reduction capability on the zwitterionic modified surface was dependent upon the use of polyethylene glycol spacer or not and the strain of microbe tested. Besides, the zwitterionic modified ones all showed greater antimicrobial adhesion capability than the surface modified with polyethylene glycol alone. On the other hand, significantly reduced platelet adhesion and activation were found, but with no statistical differences noted among the polyethylene glycol-modified surface and zwitterionic ones, with or without polyethylene glycol spacer. These suggested that the use of polyethylene glycol spacer on the zwitterionic terminated surface could further enhance the antimicrobial adhesion against gram-negative bacterial while still keeping its platelet compatibility.