Zwitterionic Surface Research Articles

The endowment of monovalent anion selectivity and antifouling property to cross-linked ion-exchange membranes by constructing amphoteric structure

Ion exchange membranes (IEMs) with high monovalent-ion selectivity show promising application in ion resource recovery. In this work, we report a kind of poly(2,6-dimethyl-1,4-phenylene oxide) (PPO)-based on amphoteric ion exchange membranes (AIEMs) having cross-linked structure. Therein, four imidazolium-terminated aliphatic chains (2IM-nC, n = 3, 6, 9, and 12) with varied number of −CH2− were used as crosslinker for cross-linking membrane matrix. Small-angle X-ray scattering tests indicate that the ion cluster sizes of the four AIEMs are evaluated with values of 0.378, 0.384, 0.388 to 0.408 nm, which possibly render the enhanced mono-valent anion selectivity of as-prepared AIEMs. Tested in the electrodialysis (ED) filled with a mixture solution of 0.05 M NaCl + 0.05 M Na2SO4, at current densities of 2.5 mA·cm−2 and 5.0 mA·cm−2, the PSO42-Cl- values of cross-linked AIEM having longer alkyl chains are 20.41 and 22.51, respectively, which are higher than AIEM with shorter cross-linker alkyl chain under the same conditions (3.5). Due to the hydrophilic surface and hydrophilic/negatively charged zwitterionic surface of AIEM, act as useful barriers via physical blocking and electrostatic repulsion, respectively, the anti-fouling performance of IEMs is improved simultaneously. In view of the superior performance, it is believed that the structure–property relationship of AIEM developed here can serve as a guideline for advanced IEMs.

Surface Grafted N‐Oxides have Low‐Fouling and Antibacterial Properties

AbstractLow‐fouling materials are often generated by surface zwitterionization with polymers. In this context, poly‐N‐oxides have recently attracted considerable attention as biomimetic stealth coatings with low protein adsorption. Herein, this study reports that poly‐N‐oxides can be grafted from plasma‐activated plastic base materials. The resulting hydrophilic surfaces have low‐fouling properties in bacterial suspensions and suppress the formation of biofilms. Moreover, efficient antibacterial activity against Gram‐negative and Gram‐positive bacteria caused by release of reactive oxygen species is observed. The latter effect is specific for polymeric N‐oxides and is most likely triggered by a reductive activation of the N‐oxide functionality in the presence of bacteria. In contrast to other zwitterionic polymers, N‐oxides combine thus low‐fouling (stealth) properties with antibacterial activity. The bioactive N‐oxide groups can be regenerated after use by common oxidative disinfectants. Poly‐N‐oxides are thus attractive antibacterial coatings for many base materials with a unique combined mechanism of action.

Zwitterionic Surface Modification of Aldehydated Sulfobetaine Copolymers for the Formation of Bioinert Interfaces

This research successfully developed a zwitterionic copolymer, poly(2-oxoethyl methacrylate-co-sulfobetaine methacrylate) poly(OxMA-co-SBMA), in which the OxMA segments have an aldehyde functional group that can undergo a nucleophilic addition reaction with an amine group to generate a Schiff base. At the same time, SBMA units are employed as antifouling groups. This copolymer is grafted via a graft-to process to the surface of an amine-based substrate to form chemical bonds by dip-coating technology and achieves antifouling properties. The synthesized monomer and copolymers are characterized by Fourier transform infrared (FTIR) spectroscopy and NMR to confirm their chemical structure. Notably, dip-coating technology uses a simple “graft-to” immersion process to achieve nonfouling and antiprotein properties. Compared to the previously reported ″graft-from″ technology, dip-coating has the advantage of a fast and simple procedure and is easy to scale up. The poly(OxMA-co-SBMA) copolymer was grafted onto the amino substrate surface by controlling the dip-coating conditions of different grafting temperatures, grafting time, concentrations of copolymer solution, and copolymer molar ratios. The prepared poly(OxMA-co-SBMA) with an optimum pOxMA/pSBMA molar ratio of 1:4 and a molecular weight of 46.8 kDa exhibited an improvement of hydrophilicity and the best resistance to protein adsorption with over 90% reduction, as well as blood cell activation, tissue cell adhesion, and bacterial attachment on the zwitterionic copolymer-grafted surfaces. The results showed that the modified samples under the best grafting conditions could effectively reduce the biofouling of biomolecules. Meanwhile, it performed well in modified amine-based plastic materials, such as polyurethane tubes and polyamide bending fabrics, which are expected to have broader bioinert application potential in biomedical materials.

Generation of N-heterocyclic carbenes (NHC) in aqueous solutions of zwitterionic imidazolium surfactant micelles

N-heterocyclic carbenes (NHCs) are important compounds that are often prepared and used in water free environment. Herein we investigate transient formation of a NHC in the headgroup of zwitterionic imidazolium sulfonate surfactants of the type 3-(1-alkyl-1H-imidazol-3-ium-3-yl)propane-1-sulfonate (ImS3-n) in water. As demonstrated by a series of 1H NMR experiments, the formation of the NHC reactive species is accelerated above the critical micelle concentration of these surfactants due to an increased local concentration of the hydroxide or deuteroxide ions (OH−/OD−) responsible for deprotonation of C(2)-H. The rate of NHC formation can be modulated by the nature and concentration of the anions of added salts, reflecting the selectivity of anion binding to the zwitterionic micelle surface. Analogous anion binding affects are observe in the NMR chemical shifts of the C(2)-H signal of the imidazolium headgroup of the surfactants. The NHCs generated at the surface of ImS3-n micelles promote the selective oxidation of 4-nitrobenzaldehyde to 4-nitrobenzoic acid, a reaction known to be catalyzed by nucleophilic carbenes. Below the cmc or in the presence of a short-chain non-micelle-forming analogue, 3-(1-methyl-1H-imidazol-3-ium-3-yl)propane-1-sulfonate (ImS3-1), no selective oxidation of 4-nitrobenzaldehyde takes place. The results demonstrate the importance of the micellar microenvironment for controlling the reactivity and selectivity of chemical reactions involving NHC species in aqueous media and can ultimately lead to greener catalytic systems.

PEG vs. zwitterions: How these surface decorations determine cellular uptake of lipid-based nanocarriers

AimTo evaluate the impact of polyethylene glycol (PEG) and zwitterionic surface decoration of lipid-based nanocarriers (NC) on cellular uptake. MethodsAnionic, neutral and cationic zwitterionic lipid-based NCs based on lecithin were compared with conventional PEGylated lipid-based NCs regarding stability in biorelevant fluids, interaction with endosome mimicking membranes, cytocompatibility, cellular uptake and permeation across intestinal mucosa. ResultsPEGylated and zwitterionic lipid-based NCs exhibited a droplet size between 100 and 125 nm with a narrow size distribution. For the PEGylated and zwitterionic lipid-based NCs only minor alterations in size and PDI in fasted state intestinal fluid and mucus containing buffer were observed, demonstrating similar bioinert properties. Erythrocytes interaction studies revealed enhanced endosomal escape properties for zwitterionic lipid-based NCs compared to PEGylated lipid-based NCs. For the zwitterionic lipid-based NCs negligible cytotoxicity on Caco-2 and HEK cells, even in the highest tested concentration of 1 % (v/v) was recorded. The PEGylated lipid-based NCs showed a cell survival of ≥75 % for concentrations ≤0.05 % on Caco-2 and HEK cells, which was considered as non-toxic. For the zwitterionic lipid-based NCs up to 60-fold higher cellular uptake on Caco-2 cells was determined compared to PEGylated lipid-based NCs. For the cationic zwitterionic lipid-based NCs the highest cellular uptake with 58.5 % and 40.0 % in Caco-2 and HEK cells, respectively, was determined. The results were confirmed visually by life cell imaging. Ex-vivo permeation experiments using rat intestinal mucosa demonstrated up to 8.6-fold enhanced permeation of the lipophilic marker coumarin-6 in zwitterionic lipid-based NCs compared to the control. Up to 6.9-fold enhanced permeation of coumarin-6 in neutral zwitterionic lipid-based NCs compared to the PEGylated counterpart was recorded. ConclusionThe replacement of PEG surfactants with zwitterionic surfactants is a promising approach to overcome the drawbacks of conventional PEGylated lipid-based NCs regarding intracellular drug delivery.

Membrane surface coated with zwitterions for fouling mitigation in membrane bioreactor: Performance and mechanism

Zwitterionic surface engineering is an effective strategy to improve membrane antifouling ability. In this present study, zwitterions were introduced onto hollow-fiber (HF) membrane via a simple flow-through coating method using zwitterionic organosilica material, and then the membrane was incorporated into a membrane bioreactor (MBR) to demonstrate improvement in fouling control. Zwitterions endowed the membrane with superior fouling resistance in the MBR; the critical flux of the membrane was improved from 25 LMH to 35 LMH, which signified higher allowable operation flux; the transmembrane pressure (TMP) development was greatly retarded, which resulted in fouling cycle extended by approximately 2 times (from 32 d to 66 d) and less cleaning frequency. Batch fouling experiments with key foulants found that zwitterion-coated membrane had superior resistance to extracellular polymeric substances (EPS) and soluble microbial polymer (SMP) adsorption. In particular, it presented exceptionally high resistance against protein adsorption. Interfacial free energy analysis revealed that zwitterions substantially altered interfacial interaction between the membrane and the EPS/SMP; the Lifshitz-van der Waals and Lewis acid-base attractive forces were obviously attenuated. As a result, the energy barrier for foulants attaching on membrane surface was greatly elevated. Our study provided a deeper insight into the antifouling mechanism of zwitterion-coated membrane and demonstrated its good potential for improving fouling control in MBR.

Single-Step Surface Hydrophilization on Ultrafiltration Membrane with Enhanced Antifouling Property for Pome Wastewater Treatment

High organic materials in palm oil mill effluent (POME) can result in serious water pollution. To date, biological treatment has been used to reduce the environmental risks of these effluents prior of their discharge into water streams. However, the effluents’ dark brownish colour remains as a significant issue that must be addressed, as it affects the overall quality of water. Although membrane technology has been frequently used to address these difficulties, membrane fouling has become a serious limitation in POME treatment. On the other hand, zwitterions with balanced charge groups have received growing interest in the fabrication of antifouling membranes due to their hydrated nature. The development of a simple and efficient covalent bonding technique to improve the stability of zwitterions on membrane surfaces remains a challenge. By grafting and co-depositing polyethylenimine (PEI)-based zwitterion (Z-PEI) with super hydrophilic polydopamine (PDA) on the surface of a commercial polysulfone (PSf) ultrafiltration membrane at ambient temperature, a new zwitterionic surface with a neutral surface charge was created (PDA/Z-PEI). This study aims to investigate the effect of different loading ratios of PDA/Z-PEI (1:1, 1:2, and 1:3) and evaluate their performance on treating brownish coloured anaerobically treated POME (AT-POME). SEM and FTIR analysis showed the successful incorporation of the PDA/Z-PEI membrane while the zwitterionic feature is indicated by zeta potential analysis. Water flux analysis demonstrated that a lower water flux was achieved for M-ZPEI membranes as compared to the PSf and PSf-MDPA membranes, attributed by the tight skin layer of PDA-ZPEI. In the development of a tight hydration layer on the membrane surface by zwitterions, zwitterionic membranes demonstrated excellent antifouling capabilities, particularly PDA/Z-PEI with a loading ratio of (1:2) with a flux recovery ratio of around 84% and colour rejection of 81.75%. Overall, this research contributes to the development of a unique coating with improved stability and antifouling properties by altering the membrane surface in a simple and reliable manner.

Zwitterionic surface modification of polyethylene via atmospheric plasma-induced polymerization of (vinylbenzyl-)sulfobetaine and evaluation of antifouling properties

Zwitterionic polymer brushes were grafted from bulk polyethylene (PE) by air plasma activation of the PE surface followed by radical polymerization of the zwitterionic styrene derivative (vinylbenzyl)sulfobetaine (VBSB). Successful formation of dense poly-(VBSB)-brush layers was confirmed by goniometry, IR spectroscopy, XPS and ToF-SIMS analysis. The resulting zwitterionic layers are about 50–100 nm thick and cause extremely low contact angles of 10° (water) on the material. Correspondingly we determined a high density of > 1.0 × 1016 solvent accessible zwitterions/cm2 (corresponding to 2,0 *10-8 mol/cm2) by a UV-based ion-exchange assay with crystal violet. The elemental composition as determined by XPS and characteristic absorption bands in the IR spectra confirmed the presence of zwitterionic sulfobetaine polymer brushes. The antifouling properties of the resulting materials were evaluated in a bacterial adhesion test against gram-positive bacteria (S. aureus). We observed significantly reduced cellular adhesion of the zwitterionic material compared to pristine PE. These microbiological tests were complemented by tests in natural seawater. During a test period of 21 days, confocal microscopy revealed excellent antifouling properties and confirmed the operating antifouling mechanism. The procedure reported herein allows the efficient surface modification of bulk PE with zwitterionic sulfobetaine polymer brushes via a scalable approach. The resulting modified PE retains important properties of the bulk material and has excellent and durable antifouling properties.

Surface Zwitterionization via Grafting of Epoxylated Sulfobetaine Copolymers onto PVDF Membranes for Improved Permeability and Biofouling Mitigation

Grafting of zwitterionic moieties has been shown to overcome the decrease in permeability after membrane modification. Herein, we report the grafting of epoxylated sulfobetaine (poly(glycidyl methacrylate-co-sulfobetaine methacrylate or poly(GMA-co-SBMA)) zwitterionic copolymers onto polyvinylidene fluoride (PVDF) surfaces to obtain superhydrophilic and superoleophobic membranes. The three-dimensionally modified membranes simultaneously exhibit excellent fouling resistance and hemocompatibility with improved water permeability during protein filtration. The zwitterionic moiety in the bulk membrane promotes the formation of a hydration layer, resulting in a dramatic reduction in hydrophobic interactions between the membrane and proteins or bacteria. Zwitterionic polymers establish a relatively electrically neutral surface through the presence of positive and negative charge groups on their pendant, leading to a reduction of adhesion between charged protein molecules and membranes. The modified PVDF surface exhibits very high hemocompatibility for human erythrocytes, platelets, and leukocytes. In the static fouling test, this biofouling hardly adhered to the membrane surface. The developed membrane has 3 times higher water permeability than the unmodified commercial membrane. It also showed a significant improvement in antifouling performance during dynamic fouling testing. Furthermore, flux regeneration of the modified membranes is easier to achieve by simple water recirculation compared to pristine PVDF membranes. Therefore, this study provides a promising way to develop antifouling membrane surface modification, which can be potentially used for bioseparation applications.

Zwitterionic silver nanoparticle based antibacterial eye drops for efficient therapy of bacterial keratitis.

Inefficient biofilm clearance and the risk of drug resistance pose significant challenges for antibiotic eye drops in the treatment of bacterial keratitis (BK). Recently, silver nanoparticles (AgNPs) have emerged as promising alternatives to antibiotics due to their potent antibacterial activity and minimal drug resistance. However, concerns regarding the potential biotoxicity of aggregated AgNPs in tissues have limited their practical application. In this study, polyzwitterion-functionalized AgNPs with excellent dispersion stability in the ocular physiological environment were chosen to prepare antibacterial eye drops. Zwitterionic AgNPs were synthesized using a copolymer, poly(sulfobetaine methacrylate-co-dopamine methacrylamide) (PSBDA), as a stabilizer and a reducing agent. The resulting antibacterial eye drops, named ZP@Ag-drops, demonstrated outstanding biocompatibility in in vitro cytotoxicity tests and in vivo rabbit eye instillation experiments, attributed to the zwitterionic PSBDA surface. Furthermore, the ZP@Ag-drops exhibited strong antibacterial activity against multiple pathogenic bacteria, particularly in penetrating and eradicating biofilms, due to the synergistic bactericidal effect of the released Ag+ and reactive oxygen species (ROS). Importantly, in vivo BK rabbit models showed that the ZP@Ag-drops effectively inhibited corneal infection and prevented ocular tissue damage, surpassing the therapeutic effect of commercial levofloxacin eye drops (LEV-drops). Overall, this study presents a promising alternative option for the effective treatment of BK using antibacterial eye drops.

Distinct Antifouling Mechanisms on Different Chain Densities of Zwitterionic Polymers.

Antifouling polymer coating surfaces are used in widespread industries applications. Zwitterionic polymers have been identified as promising materials in developing polymer coating surfaces. Importantly, the density of the polymer chains is crucial for acquiring superior antifouling performance. This study introduces two different zwitterionic polymer density surfaces by applying molecular modeling tools. To assess the antifouling performance, we mimic static adsorption test, by placing the foulant model bovine serum albumin (BSA) on the surfaces. Our findings show that not only the density of the polymer chain affect antifouling performance, but also the initial orientation of the BSA on the surface. Moreover, at a high-density surface, the foulant either detaches from the surface or anchor on the surface. At low-density surface, the foulant does not detach from the surface, but either penetrates or anchors on the surface. The anchoring and the penetrating mechanisms are elucidated by the electrostatic interactions between the foulant and the surface. While the positively charged ammonium groups of the polymer play major role in the interactions with the negatively charged amino acids of the BSA, in the penetrating mechanism the ammonium groups play minor role in the interactions with the contact with the foulant. The sulfonate groups of the polymer pull the foulant in the penetrating mechanism. Our work supports the design of a high-density polymer chain surface coating to prevent fouling phenomenon. Our study provides for the first-time insights into the molecular mechanism by probing the interactions between BSA and the zwitterion surface, while testing high- and low-densities polymer chains.

Zwitterionic Biomaterials.

The term "zwitterionic polymers" refers to polymers that bear a pair of oppositely charged groups in their repeating units. When these oppositely charged groups are equally distributed at the molecular level, the molecules exhibit an overall neutral charge with a strong hydration effect via ionic solvation. The strong hydration effect constitutes the foundation of a series of exceptional properties of zwitterionic materials, including resistance to protein adsorption, lubrication at interfaces, promotion of protein stabilities, antifreezing in solutions, etc. As a result, zwitterionic materials have drawn great attention in biomedical and engineering applications in recent years. In this review, we give a comprehensive and panoramic overview of zwitterionic materials, covering the fundamentals of hydration and nonfouling behaviors, different types of zwitterionic surfaces and polymers, and their biomedical applications.

Zwitterionic metal-organic frameworks modified polyamide membranes with enhanced water flux and antifouling capacity

Antifouling properties are considered to be crucial parameter to polyamide (PA) composite nanofiltration (NF) membranes for practical applications. In this study, an antifouling material, surface zwitterionization of Metal-organic frameworks (Z-MIL-101 (Cr)) was firstly prepared by decorating zwitterionic polymer onto the MOFs surface. Subsequently, a novel type of MOFs-based hybrid membranes were fabricated via mixing the Z-MIL-101 (Cr) nanoparticle with the organic matrix by interfacial polymerization technique. The most optimal hybrid membrane had a high water permeation of 26 L m−2 h−1 bar−1, which was 2.1 times higher than that pristine PA membrane, while the retention for Na2SO4 was still kept at a considerably high value of 93%. The significant increased water flue can attribute to the existence of water channels generated by the Z-MIL-101 (Cr). More important, the antifouling property of the hybrid membrane was much better than that pristine PA, which was due to the formation of superhydrophilic liquid layer surrounding the zwitterionic groups. The combination of the micropore structure of the MOFs and the excellent antifouling properties of the decorated zwitterionic polymer effectively improved separation performances and antifouling ability, which makes these hybrid membranes promising for water purification.

Hydration and antibiofouling of TMAO-derived zwitterionic polymers surfaces studied with atomistic molecular dynamics simulations

Zwitterionic polymers have emerged as a class of highly effective ultralow fouling materials for critical marine coating and biomedical applications. The recently developed trimethylamine N-oxide (TMAO)-derived zwitterionic polymers have demonstrated excellent antibiofouling capability in various chemical environments; however, it remains unclear how they interact with proteins at the microscopic level. To further investigate the antifouling mechanisms, we performed atomistic molecular dynamics (MD) simulations in combination with free-energy computations to provide an in-depth molecular understanding of the interactions of TMAO polymer brush (pTMAO) surfaces with proteins of opposite charges (positively charged lysozyme and negatively charged barnacle cement protein) in aqueous environments (pure water and saline solution). Our simulations revealed ordered structures of a condensed hydration water layer on the pTMAO surfaces in pure and saline water. The quantitative free energy analyses showed that the pTMAO surface has small protein desorption energy, but with a strong hydration energy barrier near the polymer surfaces to resist protein adsorption compared to other biofouling surfaces. The addition of salts only has a slight effect on the pTMAO surface’s exclusion of proteins due to the small interference of the structure of interfacial water. This study provides detailed knowledge of the strong surface hydration of zwitterionic polymers and its relation to salt impact, protein adsorption, and antibiofouling behavior of these important materials.

A dual-biomimetic strategy to construct zwitterionic anti-fouling membrane with superior emulsion separation performance

Developing efficient polymeric membranes for the purification of emulsified oily wastewater is of great significance but still challenging, restricted by low flux and severe membrane fouling. Endowing the intrinsically hydrophobic membranes with excellent hydrophilicity thus robust oil-fouling resistance in a facile and universal manner is highly desired. Herein, inspired by saltwater fish and mussel, we report a delicate zwitterionic surface design via co-assembly of 3-aminopropyldimethylamine oxide (APDMAO) and dopamine. Taking advantage of the direct connected positively charged and negatively charged moieties (N+-O-), APDMAO could strongly interact with water molecules via hydrogen bonds thus form a robust hydration barrier as revealed by molecular dynamics (MD) simulations and sum frequency generation (SFG) vibrational spectroscopy. Besides, APDMAO could bond with dopamine via both covalent and noncovalent interactions to regulate coating behavior and improve coating stability. Owing to the superhydrophilicity of APDMAO and the distinct adhesion of polydopamine, the modified membrane exhibits robust superhydrophilicity, underwater superoleophobicity and anti-oil-fouling capability. Consequently, the resultant membrane achieves an ultra-high water permeability of 5163 L m−2 h−1 bar−1 accompanied with an excellent oil rejection of 99.7% for the separation of mineral oil-in-water emulsion. Additionally, the separation performance remains rather stable during 20 cycles of emulsion filtration. The modified membrane also exhibits desired durability and antibacterial property, demonstrating its great promise in practical oily sewage remediation.

Zeta Potential-Based Control of CdSe/ZnS Quantum Dot Photoluminescence.

The ζ-potential of a colloidal quantum dot (QD) in solution has a strong impact on its photoluminescence emission quantum yield as well as the population lifetime. In this study we show that varying the surface charged groups on CdSe/ZnS QDs allows one to tune the ζ-potential and, with it, to control the quantum yield of emission as well as the recombination dynamics. We infer that the net charge density within the slipping plane around the QD in the solution strongly affects the nonradiative recombination processes, depending on the surface charge sign and value. For zwitterionic surface groups it is possible to tune the ζ-potential and the quantum yield by pH. As a general trend, QDs with zwitterionic surface groups produce a low (absolute) ζ-potential value and exhibit the highest quantum yield. Our results pave the way to, for example, future intracellular, time-resolved pH sensing applications with similar systems.

Accelerated Deep Learning Dynamics for Atomic Layer Deposition of Al(Me)3 and Water on OH/Si(111).

Knowledge of the detailed mechanism behind the atomic layer deposition (ALD) can greatly facilitate the optimization of the manufacturing process. Computational modeling can potentially foster the understanding; however, the presently available capabilities of the accurate ab initio computational techniques preclude their application to modeling surface processes occurring on a long time scale, such as ALD. Although the situation can be greatly improved using machine learning (ML), this technique requires an enormous amount of data for training datasets. Here, we propose an iterative protocol for optimizing ML training datasets and apply ML-assisted ab initio calculations to model surface reactions occurring during the Al(Me)3/H2O ALD process on the OH-terminated Si (111) surface. The protocol uses a recently developed low-dimensional projection technique (TDUS), greatly reducing the amount of information required to achieve high accuracy (ca. 1 kcal/mol or less) of the developed ML models. The resulting free energy landscapes reveal fine details of various aspects of the target ALD process, such as the surface proton transfer, zwitterionic surface configurations, elimination-addition/addition-elimination, and SN2 reactions as well as the role of the surface entropic and temperature effects. Simulations of adsorption dynamics predict that the maximum physisorption rate of ca. 70% is achieved at the incidence velocity urms of the reactants in the range of 15-20 Å/ps. Hence, the proposed protocol furnishes a very effective tool to study complex chemical reaction dynamics at a much reduced computational cost.

A smart antibacterial surface with switchable bacteria-antifouling and killing capabilities

A single layer zwitterionic polymer brush grafted surface with pH-responsive charge reversal capacity was prepared in a simple and widely used strategy. The amide bond of the zwitterionic polymer will break under acidic condition and undergo a charge reversal, resulting the surface to convert from an antifouling zwitterionic surface to a bactericidal cationic surface. The surface we constructed can successfully resist the attachment of initial bacteria at physiological conditions and kill bacteria on demand to defend bacterial infection, showing an attractive application in implantable medical devices.

A Readily Scalable, Clinically Demonstrated, Antibiofouling Zwitterionic Surface Treatment for Implantable Medical Devices.

Unlike growth on tissue, microbes can grow freely on implantable devices with minimal immune system intervention and often form resilient biofilms that continuously pump out pathogenic cells. The efficacy of antibiotics used to treat infection is declining due to increased rates of pathogenic resistance. A simple, one-step zwitterionic surface modification is developed to significantly reduce protein and microbial adhesion to synthetic materials and demonstrate the successful modification of several clinically relevant materials, including recalcitrant materials such as elastomeric polydimethylsiloxane. The treated surfaces exhibit robust adhesion resistance against proteins and microorganisms in both static and flow conditions. Furthermore, the surface treatment prevents the adhesion of mammalian fibroblast cells while displaying no cytotoxicity. To demonstrate the clinical efficacy of the novel technology in the real-world, a surface-treated, commercial silicone foley catheter is developed that is cleared for use by the U.S. Food and Drug Administration (K192034). 16long-term catheterized patients received surface-treated catheters and completed a Patient Global Impression of Improvement (PGI-I) questionnaire. 10out of 16patients described their urinary tract condition post implantation as "much better" or "very much better" and 72% (n=13) of patients desire to continue using the surface-treated catheter over conventional latex or silicone catheters.

Synthesis of a Stretchable Polyampholyte Hydrophilic Film with Compositional Gradient for Long‐Term Stable, Substrate‐Independent Fouling‐Resistant Coating

AbstractThe prevention of nonspecific biofouling is crucial for technological development in biomaterials and medical devices. Thus, zwitterionic materials have attracted significant attention due to their effective fouling‐resistance, long‐term durability against oxidation, and biocompatibility. However, fabricating a substrate‐independent zwitterionic surface with outstanding fouling‐resistance remains a challenge. In this study, a polyampholyte coating that satisfies the aforementioned requirements is obtained using a vapor‐phase method. The polyampholyte coating consists of a bilayer of poly(1,3,5,7‐tetramethyl‐1,3,5,7‐tetravinyl cyclotetrasiloxane) (pV4D4) and polyampholyte, poly(2‐carboxyethyl acrylate‐co‐2‐(dimethylamino)ethyl acrylate) (pCD), stacked with compositional gradient, which are obtained via sequential deposition using initiated chemical vapor deposition. The heavily crosslinked pV4D4 acts as an adhesion promoter layer that may be applied conformally to various substrate materials with high interfacial adhesion. The pCD surface exhibits a long‐lasting, superior fouling‐resistance to proteins (20.3 ± 1.8 ng cm−2 for undiluted human serum) and microorganisms. The pCD‐grad‐pV4D4 films, coupled with the stress‐dissipative gradient interface, are highly stretchable up to 50% without compromising the fouling‐resistance. The fouling‐resistance is maintained after 1 day of sonication, 10 days of water flushing, and 30 days of water shearing. Further, the pCD‐grad‐pV4D4 films are fully transparent and patternable, making them a prospective alternative for future non‐fouling biomedical applications.