Self-polymerization Of Dopamine Research Articles

Synchronously Enhanced Removal Ability and Stability of MXene through Biomimetic Modification.

Increasing environmental problems intensify the demand for high-performance environmental purification materials. MXene is a typical transition-metal carbide/nitride material with a two-dimensional geometric feature and a good deal of functional groups, and it is considered as an efficient adsorbent for removing pollutants from wastewater. However, the easy oxidation and relatively low adsorption capacity greatly restrict its application. In this study, the MXene/polydopamine (PDA) composite particles were fabricated through the biomimetic modification method of inducing the self-polymerization of dopamine in an MXene aqueous solution. Microstructure characterizations demonstrate that PDA facilitates the exfoliation of MXene. Adsorption measurements show that MXene and PDA exhibit an apparent synergistic effect in removing chromium hexavalent Cr(VI) from aqueous solution, and more PDA content leads to a larger synergistic effect. Consequently, the composite particles exhibit an ultrahigh adsorption capacity (862.3 mg/g). Specifically, even if the composite particles were stored in aqueous solution for 2 months, they still exhibit high adsorption ability with only a 3.3% loss in adsorption capacity, indirectly confirming the enhanced stability of MXene induced by PDA. Furthermore, the composite particles also show reduction ability to Cr(VI) and about 54.3% Cr(VI) can be reduced to harmless chromium trivalent Cr(III). This study provides a new method for the preparation of MXene-based adsorbents with excellent adsorption capacity and high stability, which has broad application prospects in the field of wastewater treatment.

Bioinspired SiO2/PDA/PTFE membrane with high corrosion-resistance for long-term efficient oil/water separation

Oil spills and oily wastewater from various industries caused severe harm to the environment and human life. Then the effective treatment of oily wastewater is extremely urgent. Superhydrophilicity/underwater superoleophobicity membranes are considered as a favorable choice for the separation of oily wastewater. In this work, inspired by mussel adhesive protein chemistry, the SiO2/PDA/PTFE membrane (SPP) with hydrophilic chemical components and multi-scale rough structures was prepared by the facile combination of dopamine self-polymerization and sol-gel strategy. The hydrophilic SiO2 nanoparticles (NPs) and polydopamine layer can be co-deposited on the membrane surface through Michael addition reaction, thus avoiding the problem of coating damage during oil/water separation. Moreover, the SiO2/PDA layer has hydrophilic groups and micro/nano rough structure, which makes the SPP membrane possess superhydrophilic and underwater superoleophobic properties. The properties of SPP membrane facilitate the formation of a hydration layer on the membrane surface, thus minimizing direct contact with oil droplets. During the experiment of oil/water separation, SPP membrane demonstrated excellent separation ability, the permeation flux of SPP membrane was measured to be 6183 and 4389 L m−2 h−1 for oil-water mixture and oil-in-water emulsion, respectively. The oil/water separation efficiency had also reached more than 99.7%. In addition, the SPP membrane exhibited brilliant chemical stability under harsh environments. It is worth mentioning that the SPP membrane showed superior cycling and anti-fouling performance in the separation process. These excellent performances demonstrate the great potential of SPP membranes in the industrial applications.

N, O co-doped carbon nanosheets synthesized based on polydopamine in situ grown on C3N4 template for supercapacitors

Heteroatom doped carbon materials have always been the focus of the research for supercapacitors. N, O co-doped carbon nanosheets (NOCNS) were synthesized by heating-treatment of self-polymerization of dopamine in situ grown on surface of C3N4 as a template. Morphologies and structure information were charactered by SEM, TEM, XRD, XPS, Raman and BET. The results exhibited that nanosheets morphology with thickness of about 1.4 nm and highly graphitization degree (ID/IG = 1.14). The effects of temperature and ratio of C3N4 to dopamine on electrochemical performance were investigated. The obtained NOCNS could achieve a maximum specific surface area of 190.7 m2 g−1 in an optimized condition of 800 °C and ratio of 1:2, reaching a maximum specific capacitance of 287.5 F g−1 at a current density of 0.5 A g−1. The assembled supercapacitor device could exhibit an energy density of 10.6 Wh kg−1 with a good cycle life.

A ratiometric fluorescent probe for simultaneous detection of L-ascorbic acid and alkaline phosphatase activity based on red carbon dots/polydopamine nanocomposite

Herein, efficient red carbon dots (R-CDs) were synthesized by one-step hydrothermal treatment of N-(4-amino phenyl) acetamide and (2,3-difluoro phenyl) boronic acid. The optimal emission peak of R-CDs was at 602 nm (under 520 nm excitation) and the absolute fluorescence quantum yield of R-CDs was 12.9%. Polydopamine, which was formed by the self-polymerization and cyclization of dopamine in alkaline condition, emitted characteristic fluorescence with peak position of 517 nm (under 420 nm excitation) and affected the fluorescence intensity of R-CDs through inner filter effect. L-Ascorbic acid (AA), which was the hydrolysis product of L-ascorbic acid-2-phosphate trisodium salt under the catalytic reaction of alkaline phosphatase (ALP), effectively prevented the polymerization of dopamine. Combined with the ALP-mediated AA production and the AA-mediated polydopamine generation, the ratiometric fluorescence signal of polydopamine with R-CDs was correlated closely with the concentration of both AA and ALP. Under optimal conditions, the detection limits of AA and ALP were 0.28 μM during linear range of 0.5–30 μM and 0.044 U/L with linear range of 0.05–8 U/L, respectively. This ratiometric fluorescence detection platform can efficiently shield the background interference of sophisticated samples by introducing a self-calibration as reference signal in a multi-excitation mode, which can detect AA and ALP in human serum samples with satisfactory results. Such R-CDs/polydopamine nanocomposite provides a steadfast quantitative information and makes R-CDs be excellent candidate for biosensors via combining target recognition strategy.

Synergistically induced dual-interfacial interactions in iron-nickel sulfides heterojunction encapsulated by N, S-codoped carbon matrix heightened ion-transport kinetics for sodium-storage

Exploring bimetallic sulfides of diverse metal species with well-defined nanoarchitectures and distinctive interfacial interactions is indispensable for advanced sodium-storage systems in achieving rapid electron/ion transfer kinetics, optimizing structural durability, and enhancing electrochemical energy storage. In this regard, the fabrication of a spindle-like hierarchical hollow nanocage with the dual heterointerfaces was reported utilizing N, S co-doped carbon support encapsulating hollow FeS2/NiS heterojunction (FeS2/NiS@N,S-C) through the critical steps of facile dopamine self-polymerization, followed by hydrolyzation, carbonization and further sulphuration. Benefiting from the great superiorities of superior conductivity, excellent structural robustness, abundant active reaction sites, efficient charge transport pathways, as well as fast ion-migration kinetics bestowed by creating an synergistically induced dual interfacial interaction in the ingenious nanoarchitecture, the FeS2/NiS@N,S-C composites render a significantly optimized comprehensive performance of Na+-storage, yielding a highly competitive capacity of 598.0 mAh g−1 after 600 cycles at 1.0 A g−1, and desirable cycle stability with supernormal rate capability (362.6 mAh g−1 after 1950 cycles at 20.0 A g−1), one of the best performances for FeS2- or NiS based heterojunctions. Meanwhile, the redox mechanism involving initial intercalation reaction and following conversion stage was uncovered detailly by a set of ex-situ experimental characterizations. Theoretical evidences drawn from density functional theory calculations illustrate that the formation of dual heterointerfaces in FeS2/NiS@N,S-C composites enables good conductivity, optimizes Na+ adsorption energy, and reduces activation energy for Na+ migration, which facilitates ion/electron migration and enhances reaction kinetics of the electrode.

Superwetting membrane by co-deposition technique using a novel N‑oxide zwitterionic polymer assisted by bioinspired dopamine for efficient oil–water separation

Superwetting membranes have good prospective for treatment of oil-containing wastewaters. However, development of simple and environment-friendly membranes with efficient oil–water separation performance remains a great challenge that needs to be addressed urgently. In this study, inspired by the secretion of trimethylamine-N-oxide (TMAO) by saltwater fish, we report a novel N‑oxide zwitterionic polymer (PTMAO) with ultralow fouling property possessing directly linked opposite charges in their molecules and superior hydrophilicity, as compared to conventional zwitterionic ones. Using biomimetic co-deposition technique of dopamine (DA) and PTMAO, a zwitterionic polymer network was formed via self-polymerization of DA and followed by hydrogen bonding and cation-π effects between the oxidatively generated polydopamine (PD) and PTMAO. As expected, the fabricated membrane exhibited excellent superhydrophilicity and underwater superoleophobicity. The M–PD/PT/2:2 membrane achieved high efficiency of oil–water separation performance under ultra-low-pressure conditions, with an oil–water emulsion flux of 1121.1 L/m2 h, a recovery rate of 93.1%, and oil rejection as high as 99.2% in the cyclic oil–water emulsion separation process. Meanwhile, the M–PD/PT/2:2 membrane showed excellent stability. Therefore, this work provides a new idea for the preparation of superwetting membranes using dual-biomimetic techniques for effective separation of oil–water emulsion.

Grafting of polyaniline onto polydopamine-wrapped carbon nanotubes to enhance corrosion protection properties of epoxy coating

Ordinary coatings can hardly meet the long-term corrosion protection requirements of modern industries. Incorporating high-performance fillers in these coatings is considered an effective way to solve this problem. In this work, the carbon nanotubes (CNTs) with polydopamine (PDA) modification was obtained by self-polymerization of dopamine on the surface of carbon nanotubes (CNTs), and then polyaniline (PANI) was grafted onto the surface of CNTs-PDA, and CNTs-PDA-PANI nanocomposites were successfully prepared. This novel strategy improves the dispersion of CNTs while increasing their surface active sites, which facilitates the uniform grafting of PANI onto the CNTs surface. Finally, the obtained nanocomposites were incorporated into epoxy resins (EP) to study their enhancement of epoxy coatings under both passive and active corrosion protection mechanisms. Electrochemical impedance spectroscopy (EIS) showed that the low-frequency impedance of CNTs-PDA-PANI/EP coating was still as high as 1.19 × 1010 Ωcm2 after 50 days of immersion in 3.5 wt% NaCl solution, which was about two orders of magnitude higher than that of the pure epoxy coating. The superior corrosion protection mechanism was attributed to the barrier of the nanofillers to the corrosive medium and the induction of the metal passivation film. Therefore, this nanocomposite construction strategy may have a high potential in the field of corrosion protection.

Water-dispersible and stable polydopamine coated cellulose nanocrystal-MXene composites for high transparent, adhesive and conductive hydrogels

High conductive and transparent hydrogels with adhesion function are ideal candidates for soft electronic devices. However, it remains a challenge to design appropriate conductive nanofillers to endow hydrogels with all these characteristics. The 2D MXene sheets are promising conductive nanofillers for hydrogels due to excellent electricity and water-dispersibility. However, MXene is quite susceptible to oxidation. In this study, polydopamine (PDA) was employed to protect the MXene from oxidation and meanwhile endow hydrogels with adhesion. However, PDA coated MXene (PDA@MXene) were easily flocculated from dispersion. 1D cellulose nanocrystals (CNCs) were employed as steric stabilizers to prevent the agglomeration of MXene during the self-polymerization of dopamine. The obtained PDA coated CNC-MXene (PCM) sheets display outstanding water-dispersible and anti-oxidation stability and are promising conductive nanofillers for hydrogels. During the fabrication of polyacrylamide hydrogels, the PCM sheets were partially degraded into PCM nanoflakes with smaller size, leading to transparent PCM-PAM hydrogels. The PCM-PAM hydrogels can self-adhere to skin, and possess high transmittance of 75 % at 660 nm, superior electric conductivity of 4.7 S/m with MXene content as low as 0.1 % and excellent sensitivity. This study will facilitate the development of MXene based stable, water-dispersible conductive nanofillers and multi-functional hydrogels.

A novel route for anoxygenic polymerization of dopamine via purple photosynthetic bacteria metabolism

Dopamine is an efficient building block to produce a versatile coating polymer able to adhere on a vast repertoire of material surfaces. Polydopamine, a dark-bioinspired polymer, is produced by the self-assembly of the dopamine under aerobic conditions in an alkaline environment. The presence of oxygen is crucial for self-polymerization of dopamine in aqueous solution. In this manuscript we show that is possible to drive the polymerization in absence of oxygen exploiting the metabolism of anaerobic photosynthetic purple bacteria.Graphical

Polydopamine surface functionalized submicron ZnO for broadening the processing window of 3D printable PLA composites

The “catalytic degradation” of metal oxides limits the wide application of PLA when PLA needs to be modified by adding metal oxides to achieve desired properties. Zinc oxide (ZnO) is a common and widely used agent as it can be used for many properties, such as antioxidant, antibacterial, etc. However, detrimental effects often exist on the properties of polymers after introducing the ZnO, due to the catalytic degradation. In this study, we used polydopamine (PDA) to construct ZnO@PDA core-shell submicron particles via the self-polymerization of dopamine (DA) in alkaline solution, aimed to produce a surface functionalization that would be used to control the rate of degradation of PLA by ZnO during thermal processing, and promote the preservation of mechanical properties. PLA with different contents of ZnO and ZnO@PDA were prepared by a simple melt extrusion method. The degradation behavior, mechanical properties and antibacterial activity of ZnO/PLA and ZnO@PDA/PLA were investigated. It was found that the incorporation of ZnO@PDA in PLA at different contents exhibits a dramatic control over the degradation rate when compared to that of the ZnO/PLA with the same filler content. Notably, the T5% and T50% of 3%-ZnO@PDA/PLA increased by 36.4 oC and 31.9 oC. GPC results showed the molecular weight of 3%-ZnO@PDA/PLA was only reduced by 15.8% after thermal processing. In addition, 3%-ZnO@PDA/PLA can be 3D-printed smoothly. That is to say, the introduction of ZnO@PDA can increase the processing window of PLA/ZnO composites, providing the possibility for materials that need to be included in civil application. Accordingly, ZnO@PDA/PLA samples showed higher tensile strength and elongation at break than that of corresponding ZnO/PLA samples. Regarding the antibacterial behavior, the ZnO@PDA/PLA have more bacterial growth disability effect against Gram(+) bacteria than that of pure PLA.

Facile Fabrication of Polydopamine-Functionalized Titanium Dioxide Nano/Submicro-Particles on the NiTi Substrate for Highly Efficient Solid-Phase Microextraction of Benzotriazole Ultraviolet Filters from Environmental Water Samples

A new polydopamine-functionalized titanium dioxide nano/submicro-particles (PDA@TiO2NPs) coating was successfully constructed on the surface of NiTi substrate as a solid-phase microextraction (SPME) fiber. To obtain a stable and uniform PDA@TiO2NPs coating, the NiTi fiber was hydrothermally treated for in situ growth of titanium/nickel oxide composite nanosheets (TiNiOCNSs). Subsequently, the titanium dioxide nano/submicro-particles (TiO2NPs) were electrophoretically deposited on the TiNiOCNSs coating. Finally, the polydopamine (PDA) coating was modified on the TiO2NPs coating by self-polymerization of dopamine (DA). Scanning electron microscopy (SEM) of the new PDA@TiO2NPs@TiNiOCNSs@NiTi fiber showed a popcornlike nanostructure with a larger surface area and more adsorption sites. Benefitting from the abundant hydrogen bonding, rich π-electron system, and strong hydrophobicity, the functionalized PDA@TiO2NPs@TiNiOCNSs@NiTi fiber illustrated excellent extraction capability for benzotriazole ultraviolet filters (BUvFs) among typical aromatic compounds coupled to HPLC with UV detection. The main SPME conditions such as extraction and desorption time, extraction temperature, stirring rate, and ionic strength were examined and optimized one by one. Under the optimum conditions, the calibration curves presented good linearity for BUvFs in the ranges from 0.01 µg·L−1 to 300 µg·L−1, and the correlation coefficients (r) were above 0.9990. The limits of detection (LODs, S/N = 3) were between 0.005 µg·L−1 and 0.043 µg·L−1. RSD repeatability of intraday and interday for one fiber was less than 5.3% and 6.9%, respectively. Moreover enrichment factors (EFs) ranged from 63 to 218. The recommended method can completely extract and detect trace BUvFs in different environmental water samples. Furthermore, the new fiber shows good stability and high strength.

Photocatalytic Synthesis of a Polydopamine-Coated Acellular Mega-Hemoglobin as a Potential Oxygen Therapeutic with Antioxidant Properties.

Hemoglobin-based oxygen carriers (HBOCs) are being developed to overcome limitations associated with transfusion of donated red blood cells (RBCs) such as potential transmission of blood-borne pathogens and limited ex vivo storage shelf-life. Annelid erythrocruorin (Ec) derived from the worm Lumbricus terrestris (Lt) is an acellular mega-hemoglobin that has shown promise as a potential HBOC due to the large size of its oligomeric structure, thus overcoming limitations of unmodified circulating cell-free hemoglobin (Hb). With a large molecular weight of 3.6 MDa compared to 64.5 kDa for human Hb (hHb) and 144 oxygen-binding globin subunits compared to the 4 globin subunits of hHb, LtEc does not extravasate from the circulation to the same extent as hHb. LtEc is stable in the circulation without RBC membrane encapsulation and has a lower rate of auto-oxidation compared to acellular hHb, which allows the protein to remain functional for longer periods of time in the circulation compared to HBOCs derived from mammalian Hbs. Surface coatings, such as poly(ethylene glycol) (PEG) and oxidized dextran (Odex), have been investigated to potentially reduce the immune response and improve the circulation time of LtEc in vivo. Polydopamine (PDA) is a hydrophilic, biocompatible, bioinspired polymer coating used for biomedical nanoparticle assemblies and coatings and has previously been investigated for the surface coating of hHb. PDA is typically synthesized via the self-polymerization of dopamine (DA) under alkaline (pH > 8.0) conditions. However, at pH > 8.0, the oligomeric structure of LtEc begins to dissociate. Therefore, in this study, we investigated a photocatalytic method of PDA polymerization on the surface of LtEc using 9-mesityl-10-methylacridinium tetrafluoroborate (Acr-Mes) to drive PDA polymerization under physiological conditions (pH 7.4, 25 °C) over 2, 5, and 16 h in order to preserve the size and structure of LtEc. The resulting structural, biophysical, and antioxidant properties of PDA surface-coated LtEc (PDA-LtEc) was characterized using various techniques. PDA-LtEc showed an increase in measured particle size, molecular weight, and surface ζ-potential with increasing reaction time from t = 2 to 16 h compared to unmodified LtEc. PDA-LtEc reacted for 16 h was found to have reduced oxygen-binding cooperativity and slower deoxygenation kinetics compared to PDA-LtEc with lower levels of polymerization (t = 2 h), but there was no statistically significant difference in oxygen affinity. The thickness of the PDA coating can be controlled and in turn the biophysical properties can be tuned by changing various reaction conditions. PDA-LtEc was shown to demonstrate an increased level of antioxidant capacity (ferric iron reduction and free-radical scavenging) when synthesized at a reaction time of t = 16 h compared to LtEc. These antioxidant properties may prove beneficial for oxidative protection of PDA-LtEc during its time in the circulation. Hence, we believe that PDA-LtEc is a promising oxygen therapeutic for potential use in transfusion medicine applications.

Functionalization of PCL-based nanofibers loaded with hirudin as blood contact materials

Blood-contacting materials with good mechanical property, excellent anticoagulant function and promoting effect on endothelialization are in great demand for clinical application such as vascular grafts in treating cardiovascular diseases. In this study, electrospinning nanofiber scaffolds of polycaprolactone (PCL) were functionalized by oxidative self-polymerization of dopamine (PDA) on the surface followed by the modification of anticoagulant recombinant hirudin (rH) molecules. The morphology, structure, mechanical property, degradation behavior, cellular compatibility and blood compatibility of the multifunctional PCL/PDA/rH nanofiber scaffolds were evaluated. The diameter of the nanofibers was between 270–1030 nm. The ultimate tensile strength of the scaffolds was around 4 MPa and the elastic modulus increased with the amount of rH. The degradation tests in vitro indicated that the nanofiber scaffolds began to crack on the 7th day, but still maintained the nanoscale architecture within a month. The cumulative release of rH from the nanofiber scaffold was up to 95.9 % at 30th day. The functionalized scaffolds promoted the adhesion and proliferation of endothelial cells, while resisting platelet adhesion and enhancing anticoagulation effects. The hemolysis ratios of all scaffolds were <2 %. The nanofiber scaffolds are promising candidates for vascular tissue engineering.

Preparation of antifouling zwitterion PVDF-imprinted composite membranes for selective antibiotic and oil/water emulsion separation

Molecularly imprinted composite membranes are considered to be a promising technology for the selective separation of antibiotics in wastewater. However, membrane pollution still greatly limits the practical applications of these membranes, especially in oily wastewater. In this study, an anti-fouling zwitterion PVDF-imprinted composite membrane (SPICM) was synthesized using dopamine as the functional monomer and crosslinking agent in the imprinting process. First, sulfobetaine 8 was blended with a porous PVDF membrane via a surface segregation strategy. Next, dopamine self-polymerization provided effective recognition sites and endowed the membrane surface with high hydrophilicity. The SPICM used for emulsion separation and selective tetracycline hydrochloride (TC) in wastewater. The as-prepared SPICM was able to separate various emulsions under gravity with a high flux (626 L m−2 h−1) and separation efficiencies of up to 99%. This membrane achieved a TC separation efficiency of 88.3% in oily wastewater. Therefore, the design of SPICMs with good antifouling performance provides a new strategy for the highly selective separation of active components from oily wastewater.

Polydopamine functionalized MXene for chemiresistive gas sensing: partial oxidation and optimized chemical state pinning

Two-dimensional MXene has been receiving attention for its outstanding properties of intrinsic metallic conductivity, high specific surface area and abundant surface terminations, showing great potential in gas sensing. However, it suffers from low sensing response and poor chemical stability. To address these issues, we propose a series of surface treatment to anchor interaction sites onto MXene, and to pin its optimized chemical state. Interaction sites including –OH, –NH2, and –O– were functionalized through self-polymerization of dopamine and controlled oxidation of the MXene base. These functionalized groups can interact with gas molecules through hydrogen bonding; besides, multiple Schottky barriers are generated within the sensing layer, thus improving formaldehyde sensing response by over 16-fold in comparison with pristine MXene. This optimized sensing state was further pinned through a hydrophobic treatment, and the composite obtained demonstrated a long-term stability (larger than 25 days) as well as a high sensitivity.

Sensitive Detection of BVDV Using Gold Nanoparticle-Modified Few-Layer Black Phosphorus with Affinity Peptide-Based Electrochemical Sensor

The lethality of the bovine viral diarrhea virus (BVDV) in cattle involves inapparent infection and various, typically subclinical, syndromes. Cattle of all ages are vulnerable to infection with the virus. It also causes considerable economic losses, primarily due to reduced reproductive performance. In the absence of treatment that can completely cure infected animals, detection of BVDV relies on highly sensitive and selective diagnosis methods. In this study, an electrochemical detection system was developed as a useful and sensitive system for the detection of BVDV to suggest the direction of diagnostic technology through the development of conductive nanoparticle synthesis. As a countermeasure, a more sensitive and rapid BVDV detection system was developed using the synthesis of electroconductive nanomaterials black phosphorus (BP) and gold nanoparticle (AuNP). To increase the conductivity effect, AuNP was synthesized on the BP surface, and the stability of BP was improved by using dopamine self-polymerization. Moreover, its characterizations, electrical conductivity, selectivity, and sensitivity toward BVDV also have been investigated. The BP@AuNP-peptide-based BVDV electrochemical sensor exhibited a low detection limit of 0.59 copies mL-1 with high selectivity and long-term stability (retaining 95% of its initial performance over 30 days).

Multifunctional porous poly (L-lactic acid) nanofiber membranes with enhanced anti-inflammation, angiogenesis and antibacterial properties for diabetic wound healing

With increased diabetes incidence, diabetic wound healing is one of the most common diabetes complications and is characterized by easy infection, chronic inflammation, and reduced vascularization. To address these issues, biomaterials with multifunctional antibacterial, immunomodulatory, and angiogenic properties must be developed to improve overall diabetic wound healing for patients. In our study, we prepared porous poly (L-lactic acid) (PLA) nanofiber membranes using electrospinning and solvent evaporation methods. Then, sulfated chitosan (SCS) combined with polydopamine-gentamicin (PDA-GS) was stepwise modified onto porous PLA nanofiber membrane surfaces. Controlled GS release was facilitated via dopamine self-polymerization to prevent early stage infection. PDA was also applied to PLA nanofiber membranes to suppress inflammation. In vitro cell tests results showed that PLA/SCS/PDA-GS nanofiber membranes immuomodulated macrophage toward the M2 phenotype and increased endogenous vascular endothelial growth factor secretion to induce vascularization. Moreover, SCS-contained PLA nanofiber membranes also showed good potential in enhancing macrophage trans-differentiation to fibroblasts, thereby improving wound healing processes. Furthermore, our in vitro antibacterial studies against Staphylococcus aureus indicated the effective antibacterial properties of the PLA/SCS/PDA-GS nanofiber membranes. In summary, our novel porous PLA/SCS/PDA-GS nanofiber membranes possessing enhanced antibacterial, anti-inflammatory, and angiogenic properties demonstrate promising potential in diabetic wound healing processes.

Mussel – Inspired biosorbent combined with graphene oxide for removal of organic pollutants from aqueous solutions

In this work, we develop a mussel-inspired biosorbent combined with graphene oxide for removal of organic dyes in water sources. The composite was prepared via self-polymerization of dopamine in weak alkaline solution containing graphene oxide at ambient condition. Morphological and structural studies revealed that polydopamine has gradually grown to cover the surface of graphene oxide flakes, partially reduced these flakes, and somehow form many grains (size around 20 nm) on the flakes instead of making very large aggregates as usual. The mass ratio between two components of the composite was also investigated to find the optimal one which provides enough surface area (20 m2.g−1) and maintain adhesive sites in order to ensure high-efficiency removal of organic molecules. The adsorption kinetics and isotherms of as-prepared adsorbent towards methylene blue were found to fit well with pseudo-first order kinetics model and Langmuir isotherm. The maximum adsorption capacity (qm) and Langmuir constant (kL) were estimated to be 270 mg.g−1 and 0.49 L. mg−1. The as-prepared bio-sorbent is very promising for remediation of water sources contaminated with cationic organic molecules and heavy metal ions.

Simple bio-inspired coating of ureteral stent for protein and bacterial fouling and calcium encrustation control.

Encrustation, caused by deposition of calcium and magnesium salts present in urine, is a common problem of indwelling urinary devices, such as ureteral stent. Encrustation was also found to be related to urinary tract infections; thus, it is necessary to prepare ureteral stents with antibacterial and antifouling surfaces to mitigate the occurrence of encrustation. In this study, commercial ureteral stent was coated with polydopamine (PDA), formed from self-polymerization of dopamine. The PDA coating was optimized in terms of dopamine concentration, pH, and coating time using response surface methodology. The chosen response parameters for optimization were calcium oxalate (CaC2 O4 ) encrustation and protein adsorption. Optimized PDA coating conditions were determined to be the following: pH9.0, 2mg/mL DA, and 3 days coating. The optimized PDA-coated ureteral stent exhibited outstanding resistance against CaC2 O4 encrustation, protein fouling, and bacterial adhesion due to its hydrophilic and functional coating layer. In comparison with the pristine ureteral stent, PDA coating was able to suppress approximately 97% and 87% of CaC2 O4 and protein adsorption, respectively. The PDA-coated ureteral stent was compared against those of commercially available ureteral stents and found to have superior encrustation and protein fouling mitigation performance. Finally, PDA coating was found to be highly stable for a storage period of 90 days, whether stored in wet or dry conditions.

Ultrafine Co nanoparticles confined in nitrogen-doped carbon toward two-electron oxygen reduction reaction for H2O2 electrosynthesis in acidic media

Electrocatalytic production of hydrogen peroxide (H2O2) by two-electron oxygen reduction reaction (2e– ORR) under acidic condition has been considered to have great application value. Co nanoparticles (CoNPs) coupled with N-doped carbon are a class of potential electrocatalysts. The effective strategies to further enhance their performances are to improve the active sites and stability. Herein, the material containing ultrafine CoNPs confined in a nitrogen-doped carbon matrix (NC@CoNPs) was synthesized by pyrolyzing corresponding precursors, which was obtained through regulating the topological structure of ZIF-67/ZIF-8 with dopamine (DA). The DA self-polymerization process induced the formation of CoNPs with smaller sizes and formed polydopamine film decreased the detachment of CoNPs from the catalyst. High density of Co-Nx active sites and defective sites could be identified on NC@CoNPs, leading to high activity and H2O2 selectivity, with an onset potential of 0.57 V (vs. RHE) and ∼90% selectivity in a wide potential range. An on-site electrochemical removal of organic pollutant was achieved rapidly through an electro-Fenton process, demonstrating its great promise for on-site water treatment application.