Mussel-inspired Method Research Articles

Multienzyme Immobilization on PVDF Membrane via One-Step Mussel-Inspired Method: Enhancing Fouling Resistance and Self-Cleaning Efficiency.

Immobilizing different enzymes on membranes can result in biocatalytic active membranes with a self-cleaning capacity toward a complex mixture of foulants. The membrane modification can reduce fouling and enhance filtration performance. Protease, lipase, and amylase were immobilized on poly(vinylidene fluoride) (PVDF) microfiltration membranes using a polydopamine coating in a one-step method. The concentrations of polydopamine precursor and enzymes were optimized during the immobilization. The higher hydrolytic activities were obtained using 0.2 mg/mL of dopamine hydrochloride and 4 mg/mL of enzymes: 0.90 mgstarch/min·cm2 for amylase, 10.16 nmoltyrosine/min·cm2 for protease, and 20.48 µmolp-nitrophenol/min·cm2 for lipase. Filtration tests using a protein, lipid, and carbohydrate mixture showed that the modified membrane retained 41%, 29%, and 28% of its initial water permeance (1808 ± 39 L/m2·h·bar) after three consecutive filtration cycles, respectively. In contrast, the pristine membrane (initial water permeance of 2016 ± 40 L/m2·h·bar) retained only 23%, 12%, and 8%. Filtrations of milk powder solution were also performed to simulate dairy industry wastewater: the modified membrane maintained 28%, 26%, and 26% of its initial water permeance after three consecutive filtration cycles, respectively, and the pristine membrane retained 34%, 21%, and 7%. The modified membrane showed increased fouling resistance against a mixture of foulants and presented a similar water permeance after three cycles of simulated dairy wastewater filtration. Membrane fouling is reduced by the immobilized enzymes through two mechanisms: increased membrane hydrophilicity (evidenced by the reduced water contact angle after modification) and the enzymatic hydrolysis of foulants as they accumulate on the membrane surface.

Cellulose acetate-based electrospun nanocomposites improved by mussel-inspired polydopamine coatings and copper iodide-decorated graphene oxide: A self-disinfecting nanofibrous membrane with potential biomedical applications

Personal protective equipment and fabrics have proven their efficient use in the SARS-CoV-2 pandemic, but because germs and viruses may survive on them, they can also operate as a source of disease transmission. Self-disinfecting textiles with the potential to kill different pathogens can be used as a substitute and prevent infections. In this research, copper iodide (CuI) decorated graphene oxide nanocomposite was synthesized through a green water-based procedure, and a novel nanofibrous membrane with improved antibacterial and antiviral characteristics was prepared by a mussel-inspired method, in which polydopamine (DOPA) and CuI-decorated graphene oxide (GO-CuI) nanocomposite were coated on cellulose acetate electrospun nanofibers (CA-DOPA-GOCuI). CA-DOPA-GOCuI NFM displayed extremely good antibacterial/antiviral properties with biofilm inhibition of 50 %, and very good cell viability and proliferation even though the virus was introduced to the cell culture. Furthermore, because it accelerated the healing process, this NFM showed great promise for use as a wound dressing. This may be because it inhibits infection and has an extremely high ROS scavenging capability of 80 %. Additionally, it was shown that CA-DOPA-GOCuI NFM was non-toxic to cells and blood compatible, with cell viability that was even higher than that of the control group of untreated cells. One possible explanation for this could be the inclusion of GO, a highly biocompatible member of the graphene family, which, when combined with CuI, reduced its toxicity to normal cells. Thus, the safety of CA-DOPA-GOCuI to normal cells, favorable cell proliferation and viability, and its high toxicity to bacteria and viruses indicate its great potential to be used in a wide range of biomedical applications, specifically, self-disinfecting fabrics and wound dressings.

Alginate-modified ZnO anti-planktonic and anti-biofilm nanoparticles for infected wound healing

Bacterial infections is one of the main factors delaying the wound healing, which has become a serious challenge for healthcare systems. Zinc oxide nanoparticles (ZnO NPs), which show broad-spectrum and excellent antibacterial activity, tend to aggregate easily and therefore hardly penetrate into bacterial biofilms, showing limited anti-biofilm properties. Herein, alginate (ALG) modified ZnO NPs (ZnO@ALG) were prepared via the combination of mussel-inspired method and “thiol-Michael” click reaction, which showed excellent dispersion and biocompatibility. Besides, the interactions between ZnO@ALG and bacteria was much better than that of ZnO NPs, and makes the bacteria produced more reactive oxygen species (ROS) than bare ZnO NPs. The anti-planktonic activity of ZnO@ALG (250 μg/mL) could reach almost 100 %, which was 2–3 times higher than that of bare ZnO NPs. In addition, the ZnO@ALG could significantly accelerate the healing of S. aureus infected wounds, and the wound healing rate of ZnO@ALG group was about 79.2 %, which was significantly higher than that of ZnO NPs (∼65.8 %). This study demonstrates that the ZnO@ALG holds a great potential in the anti-planktonic and anti-biofilm fields, and the ALG-modification method can be an effective strategy to enhance the antibacterial properties of nanomaterials.

Molten salt-assisted synthesis of cotton-like dopamine-derived carbon/transition metal sulfide composites with effective microwave absorption

This report proposes a preparation route for the molten salt (MS)-assisted synthesis of cotton-like C/transition metal sulfide (TMD) composites. By using the mussel-inspired method, carbon derived from dopamine (DA) can be well combined with the TMDs synthesized by molten salt synthesis (MSS). The morphologies and structures, electromagnetic (EM) properties and MA performances were systematically analyzed. The results show that a series of synthesized cotton-like C/TMD composites exhibit efficient MA performance and are superior to many reports in the microwave absorption (MA) field. The best MA performance of cotton-like C/TMD composites can reach −63.49 dB, and the best effective absorption band (EAB) is 5.92 GHz. This work proposes a universal MS-assisted synthesis method for synthesizing composites with excellent MA performance and precise structure, which expands the application of MSS in the MA field and provides a reference for the synthesis of MA composites using the MS method combined with other methods.

Mussel-Inspired PEDOT-Incorporated Gelatin-Based Conductive Hydrogel with Flexibility and Electroactivity to Accelerate Wound Healing In Vitro

Chronic wounds are associated with a metabolically imbalanced physiological microenvironment. However, conventional wound dressings are inadequate for treating chronic wounds due to their weak bioactivity. Electroactive wound dressings are essential for modulating a myriad of biological processes, particularly antioxidant activity and cell migration. Herein, we designed a conductive hydrogel with flexible, biodegradable, and electroactive properties using a mussel-inspired method. This conductive hydrogel was prepared by inducing poly(3,4-ethylenedioxythiophene) (PEDOT) in situ polymerization in the Hofmeister effect-assisted polydopamine-functionalized gelatin hydrogel (Gel-PDA/PEDOT). The hydrogel demonstrated robust mechanical properties with compressive and tensile strengths of 3.8 and 0.13 MPa, respectively, and a conductivity of 68.7 S/m. The addition of PDA and PEDOT to the Gel hydrogel endowed the hydrogel with exceptional antioxidant properties to maintain an intracellular redox balance. Additionally, the Gel-PDA/PEDOT hydrogel, which had favorable biocompatibility, significantly increased the migration and proliferation of fibroblasts due to its electroactive properties. A cell migration experiment was performed to assess whether the flexible and electroactive Gel-PDA/PEDOT hydrogel may be a promising wound dressing in skin wound regeneration. These findings provide a strategy for fabricating a multifunctional hydrogel with potential application in bioelectronics and wound dressings.

A high-flux polydopamine/reduced graphene oxide/MOF-5 composite membrane via a mussel-inspired method for dye wastewater purification

A high-flux polydopamine/reduced graphene oxide/MOF-5 composite membrane via a mussel-inspired method for dye wastewater purification

Rational design of nanofibrous scaffolds via bionic coating: Microstructural behavior and in vitro biological evaluation

Fabricating electrospun nanofibrous scaffolds from a combination of inorganic-organic hybrid materials is proposed as a versatile process in bone tissue engineering. However, to enhance or improve the interface issues of biphasic hybrid materials is still a challenge on how to balance the preparation conditions and physicochemical properties. Here, we designed the mussel-inspired surface assembly with copper-doped mesoporous bioactive glass (Cu-MBG) into polylactic acid (PLA) substance to enhance their mechanical and biological performances. The introduction of polydopamine (PDA) into the Cu-MBG matrix was to retain the mesostructure and improve physiological stability. Also, the nanofibrous hybrid scaffolds with/without PDA (i.e., PLA/Cu-MBG@PDA, PLA/Cu-MBG) were fabricated to evaluate the microstructural, mechanical properties, and biological features. The PDA modification in such fibrous structure could not only adjust the physicochemical properties and surface hydrophilicity, but also enhance its tensile strength. PLA/Cu-MBG@PDA exhibited strength of 5.57 MPa and elongation at break of 65.75%, showing an improvement over PLA/Cu-MBG. Extensive in vitro biological evaluation showed that the PLA/Cu-MBG@PDA scaffold exhibited many superior properties such as excellent apatite-formation ability, and enhanced cell viability compared with PLA/Cu-MBG scaffold. The mussel-inspired method provided a facile and effective strategy to combine the merits of organic/inorganic phase in one system, demonstrating its potential application in bone tissue regeneration.

Mussel-Inspired Ag NPs Immobilized on Melamine Sponge for Reduction of 4-Nitrophenol, Antibacterial Applications and Its Superhydrophobic Derivative for Oil-Water Separation.

A functional material integrated with a variety of functions is highly desired in wastewater treatment. In this research, a mussel-inspired method of immobilizing silver nanoparticles on the skeleton of a melamine sponge is proposed and applied for water remediation. Ag NPs were reduced in situ and grown on a polydopamine-modified melamine sponge. The catalytic reduction of 4-nitrophenol (4-NP) in the presence of the obtained MS-PDA-Ag was evaluated, and the results demonstrated that the MS-PDA-Ag presented high catalytic reduction activity. In addition, the monolithic MS-PDA-Ag presents excellent reusability with no remarkable decrease in catalytic efficiency after multiple reuses. Owing to the immobilized Ag NPs, the MS-PDA-Ag can also effectively inhibit the growth of bacteria against both gram-positive and gram-negative species, making it possible for bacteria elimination in polluted water. To further explore the possibility of utilizing the MS-PDA-Ag for versatile applications, a superhydrophobic derivative (S-MS-PDA-Ag) was prepared by coating a low-surface-energy substance (octadecanethiol) on the surface of MS-PDA-Ag. The obtained S-MS-PDA-Ag presents the capacities of oil/organics adsorption and water repellence, which can separate the insoluble oil/organics from water. The melamine sponge immobilized with Ag NPs demonstrates prominent catalytic reduction of 4-NP, antibacterial activity and the superhydrophobic derivative presents the capacity of insoluble oil/organics separation from oil-water mixtures, exhibiting high potential in the remediation of polluted water.

Combination of Mussel Inspired Method and “Thiol-Michael” Click Reaction for Biocompatible Alginate-Modified Carbon Nanotubes

Carbon nanotubes (CNTs) have attracted great interest in biomedical fields. However, the potential toxicity and poor dispersion of CNTs have greatly limited its application. In this work, a mussel-inspired method combined with the “thiol-Michael” click reaction was used to modify the surface of CNT and improve its properties. Firstly, a CNT was treated with dopamine, and then alginate grafted with L-cysteine was anchored onto the surface of CNT via click reaction, which realized the long-time dispersion of CNT in water. Furthermore, the in vitro test also demonstrated that the alginate may improve the biocompatibility of CNT, and thus may broaden the application of CNT in the biomedical field.

Eco-friendly and one-step modification of poly(vinylidene fluoride) membrane with underwater superoleophobicity for effective emulsion separation

In this study, poly(vinylidene fluoride) (PVDF) microfiltration membrane was modified by an eco-friendly and low-cost mussel-inspired method for applications in oil/water separation. Catechol (CA) and polyamines, instead of dopamine (DA), were utilized to modify the membranes based on a facile one-step solution-immersion process. Similar to the oxidation polymerization of DA, polyamines can react with CA via Schiff base/Michael addition reaction. A homogeneous coating with micro-nano structures and superior hydrophilicity can be formed on the surface of the membrane and the inner walls of its holes. The membrane with a water contact angle of nearly 0° and a water flux above 8000 L/m2 h was obtained after being modified with 5 mM CA and tetraethylene pentaamine (TEPA) for 24 h. The micro-nano scale roughness and the superior hydrophilicity contributed to an excellent underwater superoleophobicity with oil contact angles larger than 150° and low adhesion to various oils. The as-prepared membrane was applied to separate a series of oil-in-water emulsions, and a high separation efficiency larger than 99.4 % as well as extraordinary antifouling property without discernible decay after ten cycle tests were demonstrated. Moreover, the functional coating shows good stability in acid and alkali environment with the pH values between 0 and 11, and has few impacts on the mechanical and thermal properties of the pristine membrane. Therefore, the proposed facile and low-cost preparation of the underwater superoleophobic microfiltration membrane shows great potential in practical oily wastewater treatment.

Characterization and Application to Fiber Reinforced Composite of Catechol/polyethyleneimine Modified Polyester Fabrics by Mussel-inspiration

In order to nondestructively prepare polyamine modified polyethylene glycol terephthalate (PET) fabric, codeposition of catechol and polyethyleneimine onto PET fiber was conducted by the means of mussel-inspired method. The surface morphology, composition of woven fabric were investigated by FESEM and ATR-FTIR, XPS, respectively, whose results demonstrated successful modification has taken place on PET fiber surface. The TG-DSC data proved that the melting temperature and decomposition temperature increased from 253.78 °C and 394.08 °C to 255.01 C and 398.21 °C, respectively. The surface polarity was characterized through the dynamic contact angle. The results indicated that the fabric displayed optimal surface properties at the PEI-CA mass ratio of 1:1. The modified PET fabric was utilized to prepare the fiber reinforced epoxy composite and its mechanical performances including tensile, flexural and short beam shear strength were evaluated. The obtained results indicated that the interlaminar shear strength (ILSS) has been significantly improved by 57.02 %. The novel way to modify fabrics has great potential in recycling waste fabric for preparing fiber reinforced composite.

Porous Membranes with Special Wettabilities: Designed Fabrication and Emerging Application

Porous materials have become a burgeoning research interest in materials science because of their intrinsic porous characteristics, versatile chemical compositions, and abundant functionalities. Re...

Impact of MWCO and Dopamine/Polyethyleneimine Concentrations on Surface Properties and Filtration Performance of Modified Membranes.

The mussel-inspired method has been investigated to modify commercial ultrafiltration membranes to induce antifouling characteristics. Such features are essential to improve the feasibility of using membrane processes in protein recovery from waste streams, wastewater treatment, and reuse. However, some issues still need to be clarified, such as the influence of membrane pore size and the polymer concentration used in modifying the solution. The aim of the present work is to study a one-step deposition of dopamine (DA) and polyethyleneimine (PEI) on ultrafiltration membrane surfaces. The effects of different membrane molecular weight cut-offs (MWCO, 20, 30, and 50 kDa) and DA/PEI concentrations on membrane performance were assessed by surface characterization (FTIR, AFM, zeta potential, contact angle, protein adsorption) and permeation of protein solution. Results indicate that larger MWCO membranes (50 kDa) are most benefited by modification using DA and PEI. Moreover, PEI is primarily responsible for improving membrane performance in protein solution filtration. The membrane modified with 0.5:4.0 mg mL−1 (DA: PEI) presented a better performance in protein solution filtration, with only 15% of permeate flux drop after 2 h of filtration. The modified membrane can thus be potentially applied to the recovery of proteins from waste streams.

Improved permeability and biofouling resistance of microfiltration membranes via quaternary ammonium and zwitterion dual-functionalized diblock copolymers

In order to improve permeability and biofouling resistance of microfiltration (MF) membranes, quaternary ammonium and zwitterion dual-functionalized diblock polyelectrolyte copolymers, poly(dimethylaminoethyl methacrylate-butylammonium bromide)-b-poly(sulfobetaine methacrylate) (PDB-b-PSB) prepared via RAFT polymerization, were immobilized on commercial poly(vinylidene fluoride) (PVDF) MF membrane surface via using a versatile and facile mussel-inspired method to fabricate hierarchical copolymer brushes. Hierarchical PDB-b-PSB brushes contained bottom passive anti-adhesive zwitterionic PSB layer and upper active biocidal quaternary ammonium PDB layer. The surface chemical composition and morphology characterizations of pure and modified membranes demonstrated that PDB-b-PSB copolymers were successfully grafted to the dopamine-modified membrane surface via thiol mediated Michael addition reaction, which did not significantly change the membrane pore structure. However, the initial contact angle of PDB-b-PSB modified membrane (M/PDB-b-PSB) was changed from 128° for pure membrane (M/pure) to 43.2° and became 0° within 10 s, indicating the enhanced hydrophilicity. More importantly, the M/PDB-b-PSB membrane exhibited active biocidal effects against E. coli and S. aureus with inhibition rates over 98% and the E. coli and S. aureus suspension fluxes of M/PDB-b-PSB membranes were 1.61 times and 1.35 times higher than those of M/pure membranes. The M/PDB-b-PSB membrane had excellent anti-biofouling property with a better water flux recovery rate of 72%, which was 30% higher than that of the M/pure membrane. Moreover, PDB-b-PSB brushes showed a good immobilization stability. Therefore, the approach of poly(dopamine)-assisted fabrication of anti-biofouling MF membranes with quaternary ammonium and zwitterion dual-functionalized diblock copolymers had a prospect application in membrane-based separation technology and water purification.

Surface modification of carbon nanotube with gelatin via mussel inspired method.

Carbon nanotube (CNT) has aroused much attention in biomedical field. However, the cytotoxicity and aggregation are critical factors that affect the application of carbon nanotube (CNT). Herein, gelatin was grafted on the surface of CNT via mussel-inspired method. The gelatin modified CNT can disperse homogeneously in water. The in vitro test showed that gelatin modified CNT showed much better biocompatibility than the native CNT, which may improve its potential application in biomedical field.

Improving the performance of loose nanofiltration membranes by poly-dopamine/zwitterionic polymer coating with hydroxyl radical activation

A growing number of sewage treatment plants are utilizing the membrane separation technology for wastewater bleaching and desalination. The surface characteristics of the membrane selective layer have a great impact on the filtration and separation performance. In this study, a facile mussel-inspired method was employed for fabricating loose NF membrane. Hydroxyl radical activation generated by CuSO4/H2O2 was used to realize a rapid polydopamine (PDA) deposition. To obtain an electroneutral, anti-fouling and anti-bacterial surface, a zwitterionic polymer (SBMA) was introduced for PDA/SBMA codeposition and polymerization. XPS, FTIR, SEM, AFM and water contact angle analysis were employed to investigate the characteristics of the selective layer. The RD-1S membrane (2 mg/mL PDA and 2 mg/mL SBMA utilized) shows the optimal surface property. In addition, the filtration and separation performance of multivalent salts (monovalent and divalent ion) and dyes (negatively and positively charged) were investigated in detail. The separation capability of membrane exhibited a high dye rejection and a low salt rejection. The anti-fouling performance of the RD-1S membrane was observed to be excellent, especially from the point of view of fouling resistance reversibility. The elevated surface charge might be the main reason for the significant decrease of irreversible fouling of the RD-1S membrane. Furthermore, the co-existence of chelated copper and SBMA resulted in a reliable anti-bacterial performance. Overall, the separation and anti-bacterial performance of the functional loose NF membrane were comprehensively investigated.

Robust functionalization of underwater superoleophobic PVDF-HFP tubular nanofiber membranes and applications for continuous dye degradation and oil/water separation

In this study, a novel and multifunctional polyvinylidene fluoride-co-hexafluoropropyle (PVDF-HFP)/catechol-polyethyleneimine (CA-PEI)/Ag/3-glycidyloxy propyltrimethoxysilane (KH560) tubular nanofiber membrane (TNM) for applications in dye degradation and oil/water separation was fabricated. Firstly, the PVDF-HFP tubular nanofiber membranes were modified by using a mussel-inspired method. Then, Ag nanoparticles were assembled on the nanofiber surface to improve their excellent catalytic capacity for Methylene blue (MB) and Congo red (CR). Finally, the hydrophilic KH560 was grafted on nanofiber surface and the effects of KH560 concentration on the membrane performance were investigated. The results showed that when the KH560 concentration was 3 wt%, the modified membranes possessed a higher hydrophilicity and permeability. Meanwhile, it could also effectively separate various oil-in-water emulsions with high separation rate and separation efficiency at 0.02 MPa. Moreover, the catalytic and oil/water separation performances had no discernible decay after ten cycle tests, which promoted the potential application of modified PVDF-HFP TNMs for the treatment of practical oily wastewater.

Improved thermal conductivity and electromechanical properties of natural rubber by constructing Al2O3-PDA-Ag hybrid nanoparticles

In this study, in-situ aluminum oxide-poly(dopamine)-silver (Al2O3-PDA-Ag) hybrid nanoparticles were synthesized using simple and eco-friendly approach. Al2O3 nanoparticles were first modified by PDA through mussel-inspired method, and Ag nanoparticles were then anchored on Al2O3-PDA nanoparticles surfaces through reduction of Ag+ by glucose. The as-obtained Al2O3-PDA-Ag nanoparticles were subsequently incorporated into natural rubber (NR) matrix to yield elastomer composites. The synergistic effect of Ag and Al2O3 nanoparticles resulted in high thermal conductivity of 10 vol% Al2O3-PDA-Ag/NR composite reaching up to 0.20 W/mK. This value was two-fold superior to that of pure NR (0.10 W/mK). In addition, Al2O3-PDA-Ag/NR composites showed excellent electromechanical and mechanical properties. Overall, the proposed method looks promising for future preparation of high-thermal-conductive dielectric materials.

Thermally stable and dielectric nanocomposite based on poly(arylene ether nitrile) and BaTiO3 functionalized by modified mussel-inspired route

Easy and efficient surface functionalization is critical for obtaining high-performance barium titanate (BaTiO3) based dielectric polymer composites. We here demonstrated the easy surface functionalization of barium titanate via modified mussel-inspired method, using dopamine and silane coupling agent KH550 as reactive precursors. As-modified BaTiO3 hybrid presented core-shell structure, which was further compounded with thermally stable poly(arylene ether nitrile)(PEN) via simple solution casting method, thus obtaining dielectric nanocomposite films. As a result, the dielectric constant of PEN was enhanced from 3.5 to 10.7 at 1 KHz by addition of 40 wt% BaTiO3 hybrid, due to good dispersion of BaTiO3 nanoparticles and its interfacial interaction with PEN matrix. Furthermore, as-prepared PEN composites exhibited low dielectric loss, which fluctuated in the range of 0.03 to 0.11 at 1 KHz. Besides, the thermal stability of PEN was significantly improved, and the tensile strength was well maintained even the weight ratio of BaTiO3 hybrid reached 40 wt%. Therefore, thermally stable and dielectric PEN composite films show promising application in special area where high thermal stability, high strength, and high dielectric constant are needed.

Low-cost mussel inspired poly(Catechol/Polyamine) modified magnetic nanoparticles as a versatile platform for enhanced activity of immobilized enzyme.

Owing to dopamine's excellent adhesion ability and easy modification, it has been widely applied for enzyme immobilization, while the high cost of dopamine and low activity recovery of immobilized enzyme highly impede large-scale application of immobilized enzyme. We herein developed a low-cost and ideal activity recovery enzyme immobilization strategy based on magnetic nanoparticles by replacing dopamine with cheap Catechol/tetraethylene pentamine (CPA) binary system and introducing spacer-arms. In brief, CPA was first polymerized and deposited on the surface of magnetic nanoparticles with a modified mussel-inspired method, and the generated poly(CPA) layer was further functionalized with ethylene glycol diglycidyl ether (EGDE) molecules as spacer-arms for enzyme immobilization. Subsequently, lipases as model enzymes were firmly immobilized on the surface of such amino-epoxy functionalized magnetic materials through ion exchange and covalent attachment with 180.6 mg/g support of loading capacity and 69.2% of activity recovery under the optimized conditions. Furthermore, the immobilized lipase exhibited the improved tolerance rang of pH, temperature and storage stability as well as excellent reusability. Most strikingly, the theoretical simulation and secondary structure analysis of immobilized lipase revealed that the biocompatible microenvironment and flexible tethering at interface could effectively improve performance of the immobilized enzyme and stability. Thus, this novel immobilized enzyme strategy will open up a new perspective for the development of enzyme immobilization and lower the cost of immobilized enzyme in large-scale industrial application.