Antifouling Layer Research Articles

Fabrication of POSS-centered polyester network as high anti-chlorine and anti-fouling separation layer of membrane via successive Photo-ATRP and interfacial polymerization for molecular separation

The incorporation of polyhedral oligomeric sesquisiloxane (POSS), a distinctive nanoparticle, into the membrane separation layer represents an effective strategy for enhancing the chlorine resistance of membranes. This modification contributes to both the durability of the membrane and its separation efficiency. However, POSS is easy to agglomerate, which affects the separation performance of the membrane. In this paper, POSS-centered polyhydroxy polymer (OMEPOSS-P(GMA-NMDG)) was synthesized via photo-induced atom transfer radical polymerization and used as water-soluble monomer to prepare polyester separation layer on porous substrates through interfacial polymerization with trimelanoyl chloride. The obtained POSS-centered polyester membrane exhibits a high dye removal rate exceeding 99 %, and it can realize the screening of dye molecules with different molecular weight and different charge. Notably, the membrane demonstrates excellent chlorine resistance, maintaining effective separation efficiency after exposure to sodium hypochlorite solutions at concentrations of 10 000 ppm for 96 h and 1000 ppm for 7 days. It is worth noting that the membrane showed high anti-fouling performance. This method provides a useful guideline for the development of chlorine-resistant and anti-fouling separation membranes.

DNA Aptamer Integrated Hydrogel Nanocomposites on Screen Printed Gold Electrodes for Point-of-Care Detection of Testosterone in Human Serum.

This work describes the development and evaluation of a novel electrochemical aptasensor for testosterone detection. The sensor utilizes a specifically designed DNA immobilized on a screen-printed gold electrode (SPGE) modified with a conductive hydrogel and gold nanoparticles (HG/NP) composite. The aptasensor exhibited a dose-dependent response to testosterone (0.05 to 50 ng/mL) with a detection limit of 0.14 ng/mL and a good sensitivity of 0.23 μA ng-1 mL cm-2. The sensor displayed excellent selectivity towards testosterone compared to structurally similar steroid hormones. Importantly, the incorporation of HG/NP not only improved the sensor's conductivity but also acted as an antifouling layer, minimizing signal interference from non-specific biomolecule interactions in complex biological samples like human serum. The results obtained from the aptasensor showed good correlation with a standard ELISA method, demonstrating its effectiveness in real-world scenarios.

On-demand bactericidal and self-adaptive antifouling hydrogels for self-healing and lubricant coatings of catheters

Catheter-related infections are one of the most common nosocomial infections with increasing morbidity and mortality, and robust antibacterial or antifouling catheter coatings remain great challenges for long-term implantation. Herein, multifunctional hydrogel coatings were developed to provide persistent and self-adaptive antifouling and antibacterial effects with self-healing and lubricant capabilities. Polyvinyl alcohol (PVA) with β-cyclodextrin (β-CD) grafts (PVA-Cd) and 4-arm polyethylene glycol (PEG) with adamantane and quaternary ammonium compound (QAC) terminals (QA-PEG-Ad) were crosslinked through host-guest recognitions between adamantane and β-CD moieties to acquire PVEQ coatings. In response to bacterial infections, QACs exhibit reversible transformation between zwitterions (pH 7.4) and cationic lactones (pH 5.5) to generate on-demand bactericidal effect. Highly hydrophilic PEG/PVA backbones and zwitterionic QACs build a lubricate surface and decrease the friction coefficient 10 times compared with that of bare catheters. The antifouling hydrated layer significantly inhibits blood protein adsorption and platelet activation and reveals negligible hemolysis and cytotoxicity. The dynamic host-guest crosslinking achieves full self-healing of cracks in PVEQ hydrogels, and the mechanical profiles were recovered to over 90 % after rejuvenating the broken hydrogels, exhibiting a long-term stability after mechanical stretching, twisting, knotting and compression. After subcutaneous implantation and local bacterial infection, the retrieved PVEQ-coated catheters display no tissue adhesion and 3 log folds lower bacterial number than that of bare catheters. PVEQ coatings effectively prevent the repeated bacterial infections and there are few inflammatory reactions in the surrounding tissue, while substantial lymphoid infiltration and inflammatory cell aggregation occur in muscle tissues around the bare catheter. Thus, this study demonstrates a catheter coating strategy by on-demand bactericidal, self-adaptive antifouling, self-healing and lubricant hydrogels to address medical devices-related infections. Statement of significanceIt is estimated over two billion peripheral intravenous catheters are annually used in hospitals around the world, and catheter-associated infection has become a great clinical challenge with rapidly rising morbidity and mortality. Surface coating is considered a promising approach, but substantial challenges remain in the development of coatings that simultaneously satisfy both anti-fouling and antibacterial attributes. Even more, few attempts have been made to design mechanically robust coatings and reversible antibacterial or antifouling capabilities, which are critical for long-term medical implants. To address these challenges, we propose a concise strategy to develop hydrogel coatings from commercially available poly(ethylene glycol) and polyvinyl alcohol. In addition to self-healing and lubricant capabilities, the reversible conversion between zwitterionic and cationic lactones of quaternary ammonium compounds enables on-demand bactericidal and self-adaptive antifouling effects.

An elastomer with in situ generated pure zwitterionic surfaces for fibrosis-resistant implants

Polymeric elastomers are widely utilized in implantable biomedical devices. Nevertheless, the implantation of these elastomers can provoke a robust foreign body response (FBR), leading to the rejection of foreign implants and consequently reducing their effectiveness in vivo. Building effective anti-FBR coatings on those implants remains challenging. Herein, we introduce a coating-free elastomer with superior immunocompatibility. A super-hydrophilic anti-fouling zwitterionic layer can be generated in situ on the surface of the elastomer through a simple chemical trigger. This elastomer can repel the adsorption of proteins, as well as the adhesion of cells, platelets, and diverse microbes. The elastomer elicited negligible inflammatory responses after subcutaneous implantation in rodents for 2 weeks. No apparent fibrotic capsule formation was observed surrounding the elastomer after 6 months in rodents. Continuous subcutaneous insulin infusion (CSII) catheters constructed from the elastomer demonstrated prolonged longevity and performance compared to commercial catheters, indicating its great potential for enhancing and extending the performance of various implantable biomedical devices by effectively attenuating local immune responses. Statement of significanceThe foreign body response remains a significant challenge for implants. Complicated coating procedures are usually needed to construct anti-fibrotic coatings on implantable elastomers. Herein, a coating-free elastomer with superior immunocompatibility was achieved using a zwitterionic monomer derivative. A pure zwitterionic layer can be generated on the elastomer surface through a simple chemical trigger. This elastomer significantly reduces protein adsorption, cell and bacterial adhesion, and platelet activation, leading to minimal fibrotic capsule formation even after six months of subcutaneous implantation in rodents. CSII catheters constructed from the PQCBE-H elastomer demonstrated prolonged longevity and performance compared to commercial catheters, highlighting the significant potential of PQCBE-H elastomers for enhancing and extending the performance of various implantable biomedical devices.

Oxygen Vacancies-Induced Antifouling Photoelectrochemical Aptasensor for Highly Sensitive and Selective Determination of α-Fetoprotein.

Accurate measurement of cancer markers in urine is a convenient method for tumor monitoring. However, the concentration of cancer markers in urine is so low that it is difficult to achieve their measurement. Photoelectrochemical (PEC) sensors are a promising technology to realize the detection of trace cancer markers due to their high sensitivity. Currently, the interference of nonspecific biomolecules in urine is the main reason affecting the high sensitivity and selectivity of PEC sensors in detecting cancer markers. In this work, a strategy of oxygen vacancy (OV) modulation is proposed to construct a fouling-resistant PEC aptamer sensing platform for the detection of α-fetoprotein (AFP), a liver cancer marker. The introduction of OVs induces the formation of intermediate localized states in the photoelectric material, which not only facilitates the separation of photogenerated carriers but also leads to the redshift of the light absorption edge. More importantly, OVs with positive electrical properties can be employed to modify the antifouling layer (C-PEG) with negatively charged groups through an electrostatic interaction. The synergistic effect of OVs, antifouling layer, and aptamer resulted in a TiO2/OVs/C-PEG-based PEC sensor achieves a wide linear range from 1 pg/mL to 100 ng/mL and a low detection limit of 0.3 pg/mL for AFP. In addition, the sensor successfully realized the determination of AFP in urine samples and accurately differentiated between normal people and liver cancer patients in the early and advanced stages. This project is of great significance in advancing the application of photoelectrochemical bioanalytical technology to achieve the detection of cancer markers in urine by investigating the construction of an OVs-regulated fouling-resistant sensing interface.

Polydopamine-enhanced vertically-ordered mesoporous silica film anti-fouling electrochemical aptasensor for indicator-free Vibrio parahaemolyticus discrimination using stable inherent Au signal

Vertically-ordered mesoporous silica film (VMSF) has proven to be an effective anti-interference and anti-fouling layer in the field of analysis. However, because VMSF is not stable enough in complex samples, its application in sensing field is limited. We herein use mussel-inspired multi-functional agent polydopamine (PDA) to enhance the stability of VMSF on electrode. Owing to the amino-functionalized VMSF combined with amino groups on PDA, superhydrophilicity was achieved which was proved to enhance excellent anti-fouling property. In addition, the electrodeposition of Au nanoparticles (AuNP) in the nanochannel of VMSF serving as an internal electrochemical signal shows excellent electrochemical signal stability, which provides a prerequisite for maintaining the further detection accuracy in complex samples. Finally, we validated the detection performance of the anti-fouling sensing strategy using a foodborne pathogen, Vibrio parahaemolyticus (VP), as a model target. Specifically, the aptamer was modified by covalent bond on the PDA-integrated VMSF interface surface for the recognition of VP. Using shrimp homogenate as a real sample, the anti-fouling detection performance of the aptasensor was verified. The linear range of VP detection in real samples was 103-107 CFU/mL, and the detection limit was 103 CFU/mL. The results show that the anti-fouling aptasensor has excellent anti-interference and stability. It is worth emphasizing that this strategy (using inherent Au signal) enables rapid electrochemical analysis of VP without outer indicators, greatly reducing the difficulty of constructing an electrochemical VP detection strategy.

Effects of di-ions structure of the core layer ionomer on anion exchange membrane characteristics of anti-protein fouling and electrodialysis desalination

To investigate the effects of di-ions structure of the core layer ionomer on anti-protein fouling and electrodialysis (ED) desalination performance of the tailored anion exchange membranes (AEMs), three highly conductive structural-controlled ionomers containing aliphatic bridging cage quaternary di-ammoniums, aliphatic liner quaternary di-ammoniums, and aromatic quaternary di-ammoniums respectively have been synthesized. With the help of the previously established bi-directional in-situ interpenetration method, a series of double-sided anti-fouling AEMs were successfully fabricated from the gradient cross-linked anti-fouling thin layer CA(2% SA-0.10Ca) and the tailored ionomers. These AEMs have basic and electrochemical properties suitable for ED applications, and significant anti-protein fouling ability. The results of the ED desalination evaluations at high current density with salted egg white confirm further that DABCO-MeI-CA having aliphatic-bridging-cage-di-ions with the best electrochemical properties displays the best ED performance (desalination rate (DR) = 32.16%, energy consumption (EC) = 0.27 kWh kg−1) and good ED stability. Its ED performance is better than that of commercial AMX, with an increase of 20.74% in DR and a reduction of 34.15% in EC. Protein biuret detections verify no protein-through-membrane pollution occurred in the tests. The properties of DABCO-MeI-CA are promising for high current density ED desalination of organic macromolecule-contaminated salted systems.

A superior anti-fouling electrode sensing layer based on a tannic acid–polyethyleneimine–graphene oxide nanocomposite for thrombin detection in complex biological fluids

Affinity-peptide-based electrochemical sensors have emerged as promising alternatives to conventional methods because of their superior stability, chemical adaptability, and selectivity. However, their rapid loss of sensitivity caused by inactivation of the electrode surface and biological fouling has hindered their further development. To address this issue, we fabricated a sensitive and selective bifunctional peptide-based electrochemical sensor that enables thrombin detection in complex biological fluids. To achieve this, we incorporated a nanohybrid hydrogel composed of cross-linked polyphenol (tannic acid, TA) and polyamine (polyethyleneimine, PEI) co-deposition systems containing a nanomaterial (graphene oxide, GO) into the biosensor as an anti-fouling layer. The TA-PEI-GO nanohybrid hydrogel enhanced the electron transfer process and selectivity of the biosensor, while preventing the adsorption of non-specific biomolecules. As a result, the stability of the electrode surface was improved, and functionalization of the active sites for engineered peptides was achieved in a highly oriented manner. The stability, simplicity, and ease of preparation of this nanohybrid hydrogel render it a suitable candidate for the fabrication of electrochemical biosensors that can function in complex biological fluids. The developed biosensor has the potential to facilitate the diagnosis and prognosis of coagulation disorder-related diseases, which would have a positive effect on public health.

Interaction of Pseudomonas aeruginosa with surface-modified silica studied by ultra-high frequency acoustic wave biosensor

Aim: This study aimed to examine the amount of surface non-specific adsorption, or fouling, observed by Pseudomonas aeruginosa (P. aeruginosa) on a quartz crystal based acoustic wave biosensor under different flow conditions with and without an anti-fouling layer. Methods: An electromagnetic piezoelectric acoustic sensor (EMPAS) based on electrode free quartz crystals was used to perform the analysis. Phosphate buffered saline (PBS) was flowed over the crystal surface at various flow rates from 50 μL/min to 200 μL/min, with measurements being taken at the 43rd harmonic (~864 MHz). The crystal was either unmodified, or modified with a monoethylene glycol [2-(3-silylpropyloxy)-hydroxy-ethyl (MEG-OH)] anti-fouling layer. Overnight culture of P. aeruginosa PAO1 (PAO1) in lysogeny broth (LB) was injected into the system, and flow maintained for 30 min. Results: The frequency change of the EMPAS crystal after injection of bacteria into the system was found to change based on the flow rate of buffer, suggesting the flow rate has a strong effect on the level of non-specific adsorption. The MEG-OH layer drastically reduced the level of fouling observed under all flow conditions, as well as reduced the amount of variation between experiments. Flow rates of 150 μL/min or higher were found to best reduce the level of fouling observed as well as experimental variation. Conclusions: The MEG-OH anti-fouling layer is important for accurate and reproducible biosensing measurements due to the reduced fouling and variation during experiments. Additionally, a flow rate of 150 μL/min may prove better for measurement compared to the current standard of 50 μL/min for this type of instrument.

A non-substrate-specific technique of antifouling and antiwetting Janus membrane fabrication for membrane distillation

Although Janus membranes (comprising a hydrophilic antifouling layer on a wetting-resistant membrane substrate) have shown promise in sustainable membrane distillation (MD) processes for treating industrial wastewaters, most fabrication methods are substrate-specific and lack a universal technique for robust Janus MD membranes. Here, we present a non-substrate-specific technique using polydopamine-assisted, surface-initiated atom-transfer radical-polymerization (ATRP) that grafts a zwitterionic polymer layer onto any wetting-resistant substrate. We first prepare a model omniphobic substrate by surface fluorination of a quartz fiber mat, followed by polydopamine-assisted ATRP to complete Janus membrane fabrication. The grafting of zwitterionic polymer layer with a tunable thickness (∼1–10 μm) on one side of the membrane surface, while preserving the omniphobicity of the membrane substrate, is demonstrated. The binding robustness of the two layers of disparate wettability is then shown. An excellent antifouling functionality of the Janus membrane is confirmed by complete oil detachment in a static oil-fouling test, and by the stable desalination with nearly perfect salt rejection (> 99 %) in direct contact MD using a surfactant-stabilized, crude oil-in-brine emulsion, as simulated high-salinity industrial wastewater feed. Finally, we apply our modification technique to other lab-fabricated as well as commercial non-wetting substrates to demonstrate its universal applicability for Janus membrane fabrication.

Enhanced antifouling capability of PDMS/Cu2O-anchored Fe-based amorphous coatings

Biofouling and corrosion, caused by marine organisms, pose significant challenges in the marine industry. Fe-based amorphous coatings have demonstrated remarkable corrosion resistance and hold promise for marine applications. However, they lack sufficient antifouling properties. Herein, we present a novel approach to enhance the antifouling properties of Fe-based amorphous coatings through co-modification with polydimethylsiloxane (PDMS) and cuprous oxide (Cu2O). The PDMS/Cu2O antifouling layer was successfully applied to the Fe-based amorphous coating with the bonding strength exceeding 2 MPa. The PDMS/Cu2O- anchored Fe-based amorphous coating (designated as PCA coating) demonstrates outstanding antifouling performance, showcasing 83.9 % resistance to protein, 99 % resistance to algae, high resistance to bacteria and mussel adhesion, and successful antifouling performance in practical marine field tests. The remarkable antifouling properties of the PCA coating stem from its dual capacity of killing and resisting to deter organism attachment across different length scales. And the enhanced anti-corrosion performance of the PCA coating was verified through electrochemical impedance spectra (EIS). This study presents an innovative approach to designing marine coatings with anti-fouling and anti-corrosion capabilities.

Fabrication of sandwich-structured infrared camouflaged and flexible anti-aging composite for thermal management

The design and preparation of infrared stealth materials that meet the application in complex environments is urgently demanded in military fields. In this paper, composites with low emissivity and thermal insulation are designed to be used for indoor and outdoor infrared stealth. Thereinto, nanoPE-MXene, yttrium oxide coated hollow glass microspheres (HGMs@Y2O3) and polypropylene nonwoven (PPF) were used as low emission, insulation, and antifouling layers, respectively. The sandwich-structured composite reduce the infrared radiation temperature of the 80 °C heat source object to 33.9 °C, and the average infrared emissivity of 3-15 μm is only 0.17. In addition, the infrared stealth performance of the composite is not affected by environmental changes. More importantly, the composite exhibits excellent anti-fouling and ageing resistance performance, which lays the foundation for the practical application of efficient stealth infrared materials.

Fabrication of Transparent PEGylated Antifouling Coatings via One-Step Pyrogallol Deposition.

Antifouling coatings are critical for many biomedical devices. A simple and universal technique used to anchor antifouling polymers is important in order to expand its applications. In this study, we introduced the pyrogallol (PG)-assisted immobilization of poly(ethylene glycol) (PEG) to deposit a thin antifouling layer on biomaterials. Briefly, biomaterials were soaked in a PG/PEG solution and PEG was immobilized onto the biomaterial surfaces via PG polymerization and deposition. The kinetics of PG/PEG deposition started with the deposition of PG on the substrates, followed by the addition of a PEG-rich adlayer. However, prolonged coating added a top-most PG-rich layer, which deteriorated the antifouling efficacy. By controlling the amounts of PG and PEG and the coating time, the PG/PEG coating was able to reduce more than 99% of the adhesion of L929 cells and the adsorption of fibrinogen. The ultrathin (tens of nanometers) and smooth PG/PEG coating was easily deposited onto a wide variety of biomaterials, and the deposition was robust enough to survive harsh sterilization conditions. Furthermore, the coating was highly transparent and allowed most of the UV and Vis light to pass through. The technique has great potential to be applied to biomedical devices that need a transparent antifouling coating, such as intraocular lenses and biosensors.

An electrochemical molecular assay for the detection of cancer-associated Thomsen-Friedenreich glycans.

e15046 Background: Abnormal glycosylation is a fundamental characteristic in cancer cells, where expression of glycans such as Thomsen-Friedenreich (T), Tn, and sialyl-Tn (STn) are related to particular tumour patterns. T, Tn and STn antigens are unusually short and truncated O-glycans expressed on glycoproteins synthesized within cancer cells and not normally found in healthy tissue or circulating within the blood. The association between blood circulating T-glycans and cancer progression and poor prognosis is now well-known and highlights great potential as biomarkers for cancer screening, diagnosis, and surveillance of diseases during treatment and following remission. Despite this potential, there is currently no established molecular assay for detecting or quantifying these biomarkers in blood biopsy samples. Methods: Using a test strip format reminiscent of a blood glucose test, a new electrochemical molecular assay is introduced for the detection of short O-glycans directly in unprocessed bodily fluids. This assay is based on a self-assembling sensing interface consisting of two glycoproteins, recombinant human lubricin (LUB) and peanut agglutin (PNA). In this interface, the LUB functions as both an anti-fouling layer which mitigates electrode passivation in blood and as a crucial component in the biosensing mechanism for generating readable electrical signals in the presence of target glycans. The PNA, a plant-based lectin, presents high binding specificity towards the T glycoform and functions as the sensor recognition element which is bound to the LUB through T glycans naturally present in the highly glycosylated protein backbone. In this sensing interface, electrical signals are generated by engineering a redox reporter, methylene blue into the LUB/PNA interfacial complex, where the electrical signal is altered by the capture of target glycans by PNA and its impact on the molecular dynamics of the LUB/PNA interfacial complex. Results: Using this test strip, it is possible to detect short cancer-related glycans in concentrations as low as nanomolar directly in small volumes of unprocessed whole blood. These test strips likewise show comparable results to an ELISA test developed in parallel for the detection of short O-glycans. The tests carried out with retrospective blood plasma samples from patients presenting three different tumour types, including prostate (18 patients), colorectal (15 patients), and breast cancer (6 patients), and plasma samples from healthy donors (10 different donors) showed differentiation of response signals between healthy and diseased patients. Conclusions: These findings highlight the clinical potential of this new disposable test strip for the detection of tumour associated glycans, which can be incorporated into point-of-care devices, for cancer monitoring and perhaps one day in screening and diagnosis.

Ultralow fouling electrochemical detection of uric acid directly in serum based on phase-transited bovine serum albumin and conducting polymer

Electrochemistry with antifouling sensing interfaces that effectively resist the adsorption of nonspecific biomolecules provides a powerful mean for the accurate and sensitive detection of disease biomarkers in complex biofluids. However, there are few strategies to acquire a stable and solid antifouling coating on any substrate by a simple way. Herein, a simple one-step assembly method has been adopted to construct phase-transited bovine serum albumin (PTB) antifouling layers. Prior to construction of the antifouling layers, the poly(3,4-ethylenedioxythiophene) (PEDOT) doped with 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (ionic liquid, IL) were firstly electrodeposited on bare electrodes, endowing good conductivity and catalytic capability for the developed sensor. Subsequently, with the assist of tris(2-carboxyethyl)phosphine (TCEP), the disulfide bonds of bovine serum albumin (BSA) were reduced to form PTB, which can be coated on the PEDOT-IL modified electrode to construct an antifouling electrochemical senor (PTB/PEDOT-IL/GCE) for the detection of uric acid (UA) in human serum. The UA sensor demonstrated a good linear range from 1.11 µmol/L to 798.9 µmol/L, with a high sensitivity of 0.556 µA µmol L−1 cm−2. The combination of conducting polymers with one-step assembly of PTB offers a universal and reliable method for the modification of various electrodes to determine target molecules in complex human body fluids.

Sulfobetaine-based ultrathin coatings as effective antifouling layers for implantable neuroprosthetic devices

Foreign body response (FBR), inflammation, and fibrotic encapsulation of neural implants remain major problems affecting the impedance of the electrode-tissue interface and altering the device performance. Adhesion of proteins and cells (e.g., pro-inflammatory macrophages, and fibroblasts) triggers the FBR cascade and can be diminished by applying antifouling coatings onto the implanted devices. In this paper, we report the deposition and characterization of a thin (±6 nm) sulfobetaine-based coating onto microfabricated platinum electrodes and cochlear implant (CI) electrode arrays. We found that this coating has stable cell and protein-repellent properties, for at least 31 days in vitro, not affected by electrical stimulation protocols. Additionally, its effect on the electrochemical properties relevant to stimulation (i.e., impedance, charge injection capacity) was negligible. When applied to clinical CI electrode arrays, the film was successful at inhibiting fibroblast adhesion on both the silicone packaging and the platinum/iridium electrodes. In vitro, in fibroblast cultures, coated CI electrode arrays maintained impedance values up to five times lower compared to non-coated devices. Our studies demonstrate that such thin sulfobetaine containing layers are stable and prevent protein and cell adhesion in vitro and are compatible for use on CI electrode arrays. Future in vivo studies should be conducted to investigate its ability to mitigate biofouling, fibrosis, and the resulting impedance changes upon long-term implantation in vivo.

Polyamidoamine and carboxylated cellulose nanocrystal grafted antifouling forward osmosis membranes for efficient leachate treatment via integrated forward osmosis and membrane distillation process

Organic fouling remains an intractable challenge for forward osmosis (FO) and integrated FO-membrane distillation (MD) strategy to treat landfill leachate. To address this challenge, polyamidoamine (PAMAM)/polydopamine (PDA) and carboxylated cellulose nanocrystal (CCN) were grafted gradually on the commercial thin film composite (TFC) FO membranes via chemical coupling to achieve excellent antifouling capacity. PAMAM dendrimers, with abundant terminal amines, hyperbranched structure and open interior cavity, served as a unique intermediate platform for chemically covalent attachment of CCN with high water affinity, then cooperated with CCN to form a hydrophilic and robust antifouling layer. Compared to the raw TFC membrane, the PAMAM/PDA-CCN modified TFC membrane exhibited a similar water flux of 30.6 L m−2 h−1 (LMH) accompanied with a decreased reverse salt flux of 6.9 g m−2 h−1 (gMH) by using 1 M NaCl solution as draw solution (DS) and DI water as feed solution (FS). When actual leachate was used as FS, the modified FO membranes possessed significantly enhanced antifouling capacity with a lower flux decline (≤43.7%) and a higher flux recovery rate (≥94.2%) than the raw TFC membrane (flux decline ≤59.4% and flux recovery rate ≥79.0%, respectively). The improved fouling resistance could be further demonstrated by the reduced thickness of the organic fouling layer. Eventually, the employment of the modified FO membranes improved the compatibility of the FO and MD water fluxes and achieved sustained water production. The construction of synergistic dendritic PAMAM and CCN grafted surface paves a new way for the development of high-performance water treatment membranes.

Volume Overlap Variation within Hyperbranched Polymer Brushes Resolves Topology Effects against Protein Fouling.

Hyperbranched polymer brushes with a three-dimensional dendritic structure are used in antifouling applications to obtain bioinert and compact dendritic structures. Though hyperbranched polyglycerol (HPG) is extensively utilized in the antifouling layer, there is still a lack of direct studies on the relationship between the interfacial properties and topology effect of hyperbranched polymer brushes. Here, we established the degree of chain volume overlap (Dv) to characterize the spatial shielding efficiency generated by HPG brushes and investigated the impact mechanism of the variable chain length on the interfacial physicochemical properties. The results revealed the Dv-relevant feature of performance that the most densely packed HPG brushes for a medium-length LHPG3.07 enable the functional surface to display optimal antifouling performance toward protein adsorption by forming the most effective space barrier and hydrated layer in appropriate molecular weights and graft density. Moreover, we clarified the advance of hyperbranched polymer brushes exhibited in topology effects for imparting surface-enhanced resistance to biofouling relies on the generable higher steric hindrance as compared with linear analogs. This study established a Dv-relevant evaluation model for acquiring an optimized antifouling surface based on the appropriate choice of polymer structure, topology morphologies, and grafting parameters.

Strategy based on multiplexed brush architectures for regulating the spatiotemporal immobilization of biomolecules

Functional surfaces that enable both spatial and temporal control of biomolecules immobilization have attracted enormous attention for various fields including smart biointerface materials, high-throughput bioarrays, and fundamental research in the biosciences. Here, a flexible and promising method was presented for regulating the spatiotemporal arrangement of multiple biomolecules by constructing the topographically and chemically diverse polymer brushes patterned surfaces. A series of polymer brushes patterned surfaces, including antifouling brushes patterned surface, epoxy-presenting brushes patterned surface without and with antifouling background layer, were fabricated to control the spatial distribution of protein and cell adhesion through specific and nonspecific means. The fluorescence measurements demonstrated the effectiveness of spatially regulating the density of surface-immobilized protein through controlling the areal thickness of the poly (glycidyl methacrylate) (PGMA) brush patterns, leading to various complex patterns featuring well-defined biomolecule concentration gradients. Furthermore, a multiplexed surface bearing epoxy groups and azido groups with various areal densities was fabricated for regulating the spatiotemporal arrangement of different proteins, enabling binary biomolecules patterns with higher degrees of functionality and complexity. The presented strategy for the spatiotemporal control of biomolecules immobilization would boost the development of dynamic and multifunctional biosystems.

Anti-fouling membranes for organic solvent nanofiltration (OSN) and organic solvent ultrafiltration (OSU): graft modified polybenzimidazole (PBI)

Fouling is one of the major obstacles to successful membrane-based separations. In aqueous systems, fouling is well characterised and fouling reduction techniques are established. However, in organic solvents, membrane fouling is not well understood. In this work we manufactured anti-fouling organic solvent stable polybenzimidazole (PBI) membranes by graft modifying the surface with linear poly(ethylene glycol) (PEG) and poly(propylene glycol) (PPG). Graft modification provided an effective method of reducing fouling. However, the anti-fouling properties were dependent on the interactions between the modifying polymer and the solvent. In water, the hydrophilic PEG graft modifiers had favourable modifier-water interactions and provided an anti-fouling steric layer on the surface of the membrane. However, hydrophobic PPG graft modifiers had unfavourable modifier-water interactions and provided no anti-fouling properties. Conversely, in polar organic solvents, graft modification with PPG showed superior modifier-solvent interactions, and superior anti-fouling properties, relative to graft modification with the same molecular weight PEG. In non-polar solvents, both the PEG and PPG modifiers had unfavourable modifier-solvent interactions and provided minimal anti-fouling properties. The anti-fouling properties after graft modification were closely correlated to the hydrodynamic diameter of the grafting polymer in solution, and the selection of an optimal grafting polymer for manufacturing anti-fouling OSN and OSU membranes is significantly solvent dependant.