PDA Modification Research Articles

Engineering PDA@CNTs-Enhanced sulfobetaine methacrylate hydrogels for superior flexible sensor applications

Conductive hydrogels have attracted significant attention as versatile materials for flexible sensors, with potential implementation in wearable technologies, electronic skins, and health diagnostics. However, traditional hydrogel models are frequently limited by their inadequate mechanical strength, poor conductivity, weak adhesion, and low durability, which pose significant barriers to their further application in flexible sensors. In this work, we prepared composite multifunctional hydrogels as flexible sensors, which were synthesized from sulfobetaine methacrylate SBMA) and acrylamide (AM), infused with dodecyl quaternary ammonium salt (Q12), and incorporated with poly(dopamine)-functionalized carbon nanotubes (PDA@CNTs). The PDA modification enhances the compatibility of CNTs with the hydrogel matrix. The incorporation of PDA@CNTs into the hydrogel matrix, along with the establishment of multiple dynamic bonds—such as ionic bonds, hydrogen bonds, cation-π interactions, and π-π stacking between polymer chains and PDA moieties—significantly enhances its tensile strength (53.79 kPa), toughness (134.77 kJ/m3), adhesive capabilities (29.84 kPa to paper), and electrical conductivity (0.2 S/m). Moreover, the composite hydrogel reveals a remarkable mechanical strain response, coupled with impressive stability and durability over prolonged periods. It efficiently differentiates between mild elongations (10%–40 %) and substantial elongations (50%–300 %), thereby showcasing its capability for real-time biomechanical motion monitoring. Additionally, the composite hydrogel displays remarkable photothermal antibacterial efficacy upon exposure to near-infrared (NIR) radiation, along with outstanding biocompatibility under standard conditions, thereby confirming its suitability for safe and long-term biological interactions. The exceptional functionality of these composite hydrogels renders them highly conducive to diverse applications in the realm of wearable sensor technologies.

Biosafe Polydopamine-Decorated MnO2 Nanoparticles with Hemostasis and Antioxidative Properties for Postoperative Adhesion Prevention.

Surgical bleeding and cumulative oxidative stress are significant factors in the development of postoperative adhesions, which are always associated with adverse patient outcomes. However, effective strategies for adhesion prevention are currently lacking in clinical practice. In this study, we propose a solution using polydopamine-decorated manganese dioxide nanoparticles (MnO2@PDA) with rapid hemostasis and remarkable antioxidant properties to prevent postsurgical adhesion. The PDA modification provides MnO2@PDA with enhanced tissue adhesiveness and hemocompatibility with negligible hemolysis. Furthermore, MnO2@PDA exhibits impressive antioxidant and free radical scavenging properties, protecting cells from the negative effects of oxidative stress. The hemostatic activity of MnO2@PDA is evaluated in a mouse truncated tail model and a liver injury model, with results demonstrating reduced bleeding time and volume. The in vivo test on a mouse cecal abrasion model shows that MnO2@PDA exhibits excellent antiadhesion properties coupled with alleviated inflammation around the damaged tissue. Therefore, MnO2@PDA, which exhibits high biosafety, rapid hemostasis, and beneficial antioxidant capacity, displays exceptional antiadhesion performance, holding great potential for clinical applications to prevent postoperative adhesion.

Bioceramic scaffolds with two-step internal/external modification of copper-containing polydopamine enhance antibacterial and alveolar bone regeneration capability.

Magnesium-doped calcium silicate (CS) bioceramic scaffolds have unique advantages in mandibular defect repair; however, they lack antibacterial properties to cope with the complex oral microbiome. Herein, for the first time, the CS scaffold was functionally modified with a novel copper-containing polydopamine (PDA(Cu2+‍)) rapid deposition method, to construct internally modified (*P), externally modified (@PDA), and dually modified (*P@PDA) scaffolds. The morphology, degradation behavior, and mechanical properties of the obtained scaffolds were evaluated in vitro. The results showed that the CS*P@PDA had a unique micro-/nano-structural surface and appreciable mechanical resistance. During the prolonged immersion stage, the release of copper ions from the CS*P@PDA scaffolds was rapid in the early stage and exhibited long-term sustained release. The in vitro evaluation revealed that the release behavior of copper ions ascribed an excellent antibacterial effect to the CS*P@PDA, while the scaffolds retained good cytocompatibility with improved osteogenesis and angiogenesis effects. Finally, the PDA(Cu2+)-modified scaffolds showed effective early bone regeneration in a critical-size rabbit mandibular defect model. Overall, it was indicated that considerable antibacterial property along with the enhancement of alveolar bone regeneration can be imparted to the scaffold by the two-step PDA(Cu2+) modification, and the convenience and wide applicability of this technique make it a promising strategy to avoid bacterial infections on implants.

Effects of polydopamine functionalized graphitic carbon nitride‑cerium oxide nanofiller on the corrosion resistance of epoxy coating

It's of great convenience and economy to incorporate novel functionalized nanofillers with superior anticorrosive properties to further elevate the corrosion protective period of epoxy coating. For this purpose, we fabricated finely dispersed cerium oxide grafting polydopamine modified graphitic carbon nitride (g-C3N4@PDA@CeO2) via self-polymerization method and hydrothermal technique to promote the epoxy coating's anticorrosion performance on P110 substrate. The XRD, XPS, TGA, and SEM analyses were employed to qualitatively verify the successful synthesis of g-C3N4@PDA@CeO2 nanocomposite. The results obtained from EIS experiments showed that the g-C3N4@PDA@CeO2 epoxy coating possessed superior corrosion resistance, which maintained a modulus value (|Z|0.01Hz) of 4.737 × 107 Ω cm2 after the entire soaking process. Conversely, pure epoxy coating presented the |Z|0.01Hz which became two orders of magnitude lower. Additionally, a prominent decline in the corrosion current value (Icorr = 5.122 × 10−11 A/cm2) was observed from the potentiodynamic polarization curve of g-C3N4@PDA@CeO2 epoxy coating, decreased 3 orders of magnitude better than neat epoxy (Icorr = 4.421 × 10−8 A/cm2). The enhancement mechanism on the epoxy coating's anticorrosion property could be explained by synergistic effects of PDA's modification and the grafting of CeO2 that endowed the epoxy coating with better barrier effect to electrolytes and great corrosion inhibition property, which conjointly extended corrosion protection period.

Honeycomb-like ReS2/polydopamine/Ag plasmonic composite assembled membrane substrate for rapid surface-enhanced Raman scattering analysis of 6-benzylaminopurine and alternariol in food

Herein, rhenium disulfide/polydopamine/Ag(ReS2/PDA/Ag) plasmonic composites assembled surface-enhanced Raman scattering(SERS) membrane substrates were fabricated for rapid analysis of 6-benzylaminopurine(6-BAP) and alternariol(AOH). The ReS2/PDA/Ag composites including ReS2/PDA/AgNPs and ReS2/PDA/AgNPs@thioglycolic acid(ReS2/PDA/AgNPs@TGA) were prepared via surface modification strategy and assembling method. With PDA modification, the ReS2/PDA/AgNPs improved the affinity of substrate to 6-BAP. With further TGA modification, the ReS2/PDA/AgNPs@TGA advanced the affinity between substrate and AOH. ReS2/PDA/Ag composites were assembled to SERS membrane substrate, which integrated SERS enhancement, fast separation/adsorption, and detection all-in-one. The membrane substrates exhibited good stability with relative standard deviations less than 5.5% and 6.5% for one batch and different batches, respectively. SERS methods based on the membrane substrates were developed for analysis of 6-BAP and AOH with detection limit of 24.4 and 23.6 μg/L, respectively. The methods were applied for determination of 6-BAP in bean sprout with recoveries of 87.1%− 107.0% and RSDs of 2.5%− 6.6%, AOH in pear with recoveries of 86.0%− 102.0% and RSDs of 2.9%− 8.1%, respectively. The results were confirmed by chromatographic method with relative error less than 5.5%. The analytical process completed within 35 min shows great potential in rapid food safety analysis.

Mechanical and water resistance performance of physically cross-linked poly(vinyl alcohol) composite with poly(dopamine) modified cellulose nanocrystals

A novel strategy was developed for the construction of physically cross-linked poly(vinyl alcohol)- PVA composite reinforced by poly(dopamine) modified cellulose nanocrystals (PDA@CNCs) with robust mechanical and water resistance property. The PDA@CNC hybrid had improved thermal stability and the rod-like morphology of CNCs was well preserved after the PDA modification. The Young’s modulus, tensile strength and water resistance property of physically cross-linked PDA@CNC/PVA composites were obviously improved compared with the composites without cross-linking. The improved properties of the PDA@CNC/PVA composites were attributed to the destruction of intramolecular hydrogen bond and reconstruction of intermolecular hydrogen bonds as well as ferric ions coordination cross-linking interactions. The excellent mechanical and water resistance property of the developed PDA@CNC/PVA provides a path way for the development of water induced-mechanically adaptive PDA@CNC functional nanocomposites for applications such as direct ink writing in 3D/4D printing.

Polydopamine-modified ZIF-8 nanoparticles as a drug carrier for combined chemo-photothermal osteosarcoma therapy

Single chemotherapy often causes severe adverse effects and chemoresistance which limits therapeutic efficacy. Recently, combination of chemotherapy with photothermal therapy (PTT) have received broad attention for synergistic treatment of osteosarcoma, ultimately resulting in the enhancement of therapeutic efficacy of anticancer drugs. In this study, we have developed a novel drug delivery system based on polydopamine (pDA)-modified ZIF-8 nanoparticles loaded with methotrexate (MTX) (pDA/MTX@ZIF-8 NPs). Herein, pDA modification avoided the explosive release of the drug, and improved the biocompatibility and near-infrared (NIR) light absorbance performance of nanoparticles. The as-prepared pDA/MTX@ZIF-8 NPs could be used as drug targeting delivery system and simultaneously displayed excellent photothermal effects under NIR irradiation. Biology assays in vitro indicated that the pDA/MTX@ZIF-8 NPs were able to efficiently induce MG63 cell apoptosis through reducing mitochondrial membrane potentials (MMPs), and the introduction of photothermal agents enhanced the antitumor effect and decreased the dose of chemotherapeutic drugs. Moreover, the optimized pDA/MTX@ZIF-8 NPs (40 μg/mL) exhibited better photothermal conversion performance and facilitated tumor cells death. These results triumphantly exhibit that the pDA/MTX@ZIF-8 NPs have a synergistic effect of chemo-photothermal therapy (combination index CI = 0.346) and excellent biocompatibility, which has unexceptionable prospects for the therapy of osteosarcoma.

High Uranium Extraction by Polydopamine Functionalized MXene from Aqueous Solutions

MXenes were outstanding materials for aqueous environment remediation, MXenes with a high capacity for radionuclides uranium (U(VI)) remains a challenge. In this study, a noval polydopamine functionalized MXene (defined as MXene@PDA) was successfully synthesised and evaluated for the aggregation towards U(VI) from wastewater. Versatile PDA owing functional groups provided more sites to capture contaminant ions. The mechanism research with MXene@PDA was explored by batch experiments toghther with the XPS analyses. The results revealed MXene@PDA with abundant functional groups exhibited superior elimination ability (90.4 mg/g) at pH = 5.0. The mechanism of U(VI) on MXene@PDA was primarily ascribed to the surface complexation force between the UO22+ and -OH, NH2 groups. The PDA modification of MXene materials are proved to be excellent materials for the extraction of radionuclides in the aqueous solution.

A GdW10@PDA-CAT Sensitizer with High-Z Effect and Self-Supplied Oxygen for Hypoxic-Tumor Radiotherapy.

Anticancer treatment is largely affected by the hypoxic tumor microenvironment (TME), which causes the resistance of the tumor to radiotherapy. Combining radiosensitizer compounds and O2 self-enriched moieties is an emerging strategy in hypoxic-tumor treatments. Herein, we engineered GdW10@PDA-CAT (K3Na4H2GdW10O36·2H2O, GdW10, polydopamine, PDA, catalase, CAT) composites as a radiosensitizer for the TME-manipulated enhancement of radiotherapy. In the composites, Gd (Z = 64) and W (Z = 74), as the high Z elements, make X-ray gather in tumor cells, thereby enhancing DNA damage induced by radiation. CAT can convert H2O2 to O2 and H2O to enhance the X-ray effect under hypoxic TME. CAT and PDA modification enhances the biocompatibility of the composites. Our results showed that GdW10@PDA-CAT composites increased the efficiency of radiotherapy in HT29 cells in culture. This polyoxometalates and O2 self-supplement composites provide a promising radiosensitizer for the radiotherapy field.

Mussel-inspired functionalization of electrospun scaffolds with polydopamine-assisted immobilization of mesenchymal stem cells-derived small extracellular vesicles for enhanced bone regeneration

Mesenchymal stem cells-derived small extracellular vesicles (MSCs-sEV) have shown promising prospects as a cell-free strategy for bone tissue regeneration. Here, a bioactive MSCs-sEV-loaded electrospun silk fibroin/poly(ε-caprolactone) (SF/PCL) scaffold was synthesized via a mussel-inspired immobilization strategy assisted by polydopamine (pDA). This pDA modification endowed the as-prepared scaffold with high loading efficiency and sustained release profile of sEV. In addition, the fabricated composite scaffold exhibited good physiochemical, mechanical, and biocompatible properties. In vitro cellular experiments indicated that the MSCs-sEV-loaded composite scaffold promoted the adhesion and spreading of preosteoblast and endothelial cells, as well as enhanced osteogenic differentiation and angiogenic activity. In vivo experiments showed that the functionalized electrospun scaffolds promoted bone regeneration in a rat calvarial bone defect model. Results suggest that the developed MSCs-sEV-anchored pDA-modified SF/PCL electrospun scaffolds possess high application potential in bone tissue engineering owing to their powerful pro-angiogenic and -osteogenic capacities, cell-free bioactivity, and cost effectiveness.

Fabrication of di-selective adsorption platform based on deep eutectic solvent stabilized magnetic polydopamine: Achieving di-selectivity conversion through adding CaCl2

Dynamic conversion process from selective adsorption of MG by MPDA-PDES 1 to selective adsorption of SY. • A new strategy for stabilizing and modifying MPDA by DESs was proposed. • A selective dyes adsorption method from binary dyes solution based on MPDA-PDES 1 adsorbent was established. • The addition of CaCl 2 made MPDA-PDES 1 from selectively adsorb MG to selectively adsorb SY. • MPDA-PDES 1 exhibited superior stability and can be reused six times continuously. Seeking effective synthesis strategy of adsorbents with di-selective adsorption ability to remove dyes in wastewater is of great significance for solving the increasing environmental problems. Hence, three deep eutectic solvents (DESs) were synthesized and polymerized on the surface of magnetic (Fe 3 O 4 ) polydopamine (MPDA), in which DES acted as both stabilizer and surface modifier for PDA coating. The fabricated nanoparticles (named as MPDA-PDES) were used as adsorbents for selective adsorption of binary dyes solution. Langmuir and Dubinin-Radushkevich isotherm models were suitable to describe adsorption process of malachite green (MG) and sunset yellow FCF (SY) on MPDA-PDES 1 , respectively, indicated that the adsorption of MG was monolayer uptake, and that of SY was physical adsorption. The effect of solution pH and ionic strength suggested that electrostatic interaction was mainly adsorption driving force. Interestingly, the addition of CaCl 2 in adsorption system realized dynamic transformation from selective adsorption of MG by MPDA-PDES 1 to selective adsorption of SY. And selectivity factor reduced from 37.57 to 0.30. MPDA-PDES 1 adsorbent possessed excellent anti-interference ability, regeneration and reusability, can be continuously reused six times and adsorption capacity remained basically unchanged. The adsorption of MG-SY from synthetic wastewater manifested that MPDA-PDES 1 had unlimited potential for selective removal of target dyes in actual wastewater. Mechanism exploration revealed that MPDA stabilized by DES containing long-chain alkyl groups exhibited better selective adsorption capacity for cationic dyes in binary dyes solutions. This was due to the synergistic effect of electrostatic interaction, hydrophobic interaction, hydrogen bonding and π-π stacking between MPDA-PDES 1 and dyes. Therefore, proposed DES-based PDA modification strategy improved the stability and reusability of PDA materials, and achieved outstanding selective adsorption ability because of tailorability of DES structure, which provided new ideas for design and synthesis of high-efficiency adsorbents.

Bone Morphogenetic Protein-2-Activated 3D-Printed Polylactic Acid Scaffolds to Promote Bone Regrowth and Repair.

Uneven distribution of pores, lack of connection between holes, low reproducibility, insufficient mechanical strength, and incomplete volatility of organic solvents are some problems associated with traditional tissue engineering methods for bone defect repair. These characteristics reduce the quality and stability of products. This study uses 3D printing (3DP) to fabricate a biocompatible poly(lactic) acid-based scaffold for repairing bone tissue. Hence, three different types of scaffolds are assessed: a freeze-dried polylactic acid (PLA) scaffold constructed using the traditional freeze-extraction method; a 3D-PLA scaffold produced through the 3DP technique; and a 3D-PLA-bone morphogenetic protein-2 (BMP-2) scaffold that is prepared using 3DP technology, with the addition of BMP-2. To enhance biological activity, polydopamine (pDA) is used to graft BMP-2 on the surface of the 3D-PLA-BMP-2 scaffold. Then, the scaffolds are implanted into the bilateral femoral condyles of rabbits, and their ability to repair the bone tissue defects is tested. The results of the experiments reveal that the 3DP scaffolds are more biocompatible than the ones produced through the traditional manufacturing methods because they enhance cell adhesion and differentiation after pDA modification and BMP-2 fixation. In the future, the 3DP products may be applied for the repair of larger bone defects in the clinical setting.

Surface-modified PVA/PVDF hollow fiber composite membrane for air dehumidification

This study focused on the water vapor removal efficiency by the surface-modified poly(vinyl alcohol)/poly(vinylidene difluoride) (PVA/PVDF) hollow fiber composite membranes with poly(dopamine) (PDA) in the dehumidification process. Two different ways of PDA modification were experimentally investigated and examined in terms of the separation performance of water vapor. A laboratory-scale testing device was set up to measure the water vapor permeance and the water vapor/H2 selectivity. Compared with the pristine PVA/PVDF membrane, the membrane modified using PVA/PDA mixture formed a dense and thin layer with high nitrogen solubility, which was not conducive to improve the water vapor removal efficiency. In contrast, the three-layer PDA–PVA/PVDF-modified membrane with PDA significantly enhanced the dehumidification performance. The influences of modification conditions (PDA concentration and PDA modification time) on the water vapor permeance and water vapor/H2 selectivity of PDA–PVA/PVDF-modified membrane were further studied. The highest water vapor permeance of 2898 GPU was obtained at certain conditions (0.1 g L−1 PDA solution and modification time of 30 min). It was demonstrated that the surface modification with PDA could play an important role in enhancing the hydrophilicity and water vapor/H2 separation performance for PVA/PVDF composite membranes.

Polydopamine modification electrospun polyacrylonitrile fibrous membrane with decreased pore size and dendrite mitigation for lithium ion battery

Large pore size of fibrous membrane (FM) deteriorates the cycle lifetime and rate capabilities, and the way of obtaining FM with improved electrolyte wettability and decreased pore size is still challenging. Herein, we report a facile method for the fabrication of the polydopamine modification polyacrylonitrile (PDA@PAN) FM via the combination of the spin coating and electrospinning techniques. The PDA coating increases the fiber diameter and the surface roughness of the PAN fibers, thus decreasing the pore size and mitigating the lithium dendrite formation by uniformly distributing Li-ion flux. Meanwhile, PDA modification not only improves the affinity for electrolyte and enhances the ion conductivity (1.39 mS cm−1), but also doubles the stress strength (13.92 MPa) because of the formation of more adhesion structure. Consequently, both the Li/LiFePO4 and Li/Li4Ti5O12 cells involving PDA@PAN FM demonstrate more stable cycle life and better rate capability compared with those of cells based on PAN FM and Celgard membrane. The work also provides a promising separator fabrication strategy for other energy storage systems.

Fabrication of natural rubber dielectric elastomers with enhanced thermal conductivity via dopamine chemistry

Abstract Herein, boron nitride (BN) is modified by bio-inspired dopamine chemistry to increase thermal conductivity of natural rubber (NR) dielectric elastomer. With in situ self-polymerization of dopamine, poly(dopamine) (PDA) is coated on the BN platelets surface. After PDA modification, the BN platelets are homogeneously dispersed in polymeric matrix, resulted in enhanced mechanical properties, thermal conductivity and dielectric properties. The NR composites acquire the maximum thermal conductivity coefficient (0.46 W/mK), which is approximately 460% of pure NR without thermal conductive filler (0.10 W/mK). Moreover, the NR composites exhibit high dielectric strength and large energy density due to the PDA modification on BN platelets.

Single-step functionalization of poly-catecholamine nanofilms for ultra-sensitive immunosensing of ubiquitin carboxyl terminal hydrolase-L1 (UCHL-1) in spinal cord injury

Rapid, selective, and ultra-sensitive detection of brain and spinal cord injury markers in bodily fluids is an unmet clinical need. In this work, Polycatecholamine as a rich source of amine moieties was used for single-step fabrication of ultrasensitive immunosensors for the detection of Ubiquitin carboxyl-terminal hydrolase (UCHL-1) biomarker of brain and spinal cord injuries and address the clinical need. The surface of graphene electrodes was modified by electropolymerizing aqueous solution of dopamine (DA) and norepinephrine (NE) monomers for generating polycatecholamines nanofilms on the surface of graphene screen printed electrodes (GSPE) in a single functionalization step. Amine moieties of the polymer allowed immobilization of UCHL-1 antibody on the electrode. The single-step modification of GSPE offered a simple, ultrasensitive, and stable production of immunosensors for the detection of UCHL-1. The operational range of the UCHL-1 immunosensor developed with Polynorepinephrine pNE-modified is 0.1 pg mL−1 – 105 pg mL−1 (LOD: 1.91 pg mL−1), and 1 pg mL−1 – 105 pg mL−1 (LOD: 0.70 pg mL−1) with Polydopamine (pDA) modification, satisfying the clinical range. Both pNE and pDA modified immunosensors, detected UCHL-1 spiked in phosphate buffer saline, artificial cerebrospinal fluid, and serum. Along with the sensitive detections, selective performances were recorded in the above matrices in the presence of interfering neurotransmitters GABA and Glutamate as well as glial fibrillary acidic protein (GFAP). Upon testing clinical samples of spinal cord injury patients and healthy controls, both pNE and pDA immunosensors, delivered a comparable response for UCHL-1, thereby, making immunosensors useful for clinical settings.

Fabrication of ploydopamine–kaolin supported Ag nanoparticles as effective catalyst for rapid dye decoloration

In this work, silver nanoparticles supported on polydopamine-kaolin composite (PDA-kaolin-Ag) was fabricated by an in-situ reduction method with PDA as both reductant and stabilizer. The morphology, composition, and structure of PDA-kaolin-Ag composite were characterized by transmission electron microscopy (TEM), X-ray powder diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The catalytic reduction tests confirmed the importance of PDA modification and high catalytic activities of this as-prepared PDA-kaolin-Ag composite towards a model dye Rhodamine B. The catalytic reduction processes followed pseudo-first order kinetics. Meanwhile, this catalyst showed excellent stability and recyclability for dye decoloration. Furthermore, this composite also exhibited good catalytic performance on methylene blue, methyl orange, and Congo red. These results suggest that PDA-kaolin-Ag composites can be used as efficient and cost-effective catalyst for the decoloration of various organic dyes.

Functionalization of Polydopamine via the Aza-Michael Reaction for Antimicrobial Interfaces.

Polydopamine (pDA) coatings afford tremendous versatility due to their capabilities to provide substrate-independent functionalization with a wide range of amine- and thiol-containing molecules. In this work, we developed a new and facile conjugation approach to the formation of β-amino carbonyl linkages between pDA and acrylate/acrylamide molecules via the aza-Michael reaction. Sulfobetaine acrylamide (SBAA), sulfobetaine methacrylate (SBMA), and poly(ethylene glycol) methacrylate (PEGMA) were employed to graft onto pDA films, giving rise to formation of antifouling coatings. Because of the universal adhesive property of pDA, the coating strategy was applied to different substrates, including TiO2, gold, SiO2, Nitinol alloy, polystyrene, and poly(dimethylsiloxane). The variation of surface chemistry and surface wettability upon pDA modification and subsequent conjugation was monitored with X-ray photoelectron spectroscopy (XPS) and water contact angle measurements. Antifouling properties of coatings were challenged by three common Gram-negative and Gram-positive bacteria. Cytocompatibility of the coatings with NIH-3T3 fibroblasts was accessed using MTT assay. The results showed that pDA coatings grafted with SBAA exhibited superhydrophilicity and excellent fouling resistance likely due to the high chemical reactivity of acrylamide, leading to high grafting density. In addition, dual functional coatings containing passive and active antibacterial components were constructed through the in situ deposition of antimicrobial agent, silver nanoparticles, in pDA, followed by the grafting of SBAA for bacterial repellence. The composite coatings allowed reducing adsorption of E.coli by >95%, while killing attached bacteria by up to 98% upon the releasing of Ag(+) ions as measured by inductively coupled plasma mass spectrometry. Consequently, this work paves a new avenue to the grafting strategy to engineer pDA and to the functional bioinspired antifouling interfaces in a substrate-independent fashion.

Surface modification of MPEG-b-PCL-based nanoparticles via oxidative self-polymerization of dopamine for malignant melanoma therapy.

To enhance the therapeutic effects of chemotherapy on malignant melanoma, paclitaxel (PTX)-loaded methoxy poly(ethylene glycol)-b-poly(ε-caprolactone) nanoparticles (MPEG-b-PCL NPs) that had their surfaces modified with polydopamine (PTX-loaded MPEG-b-PCL NPs@PDA) were prepared as drug vehicles. The block copolymer MPEG-b-PCL was synthesized by ring-opening polymerization and characterized by proton nuclear magnetic resonance spectroscopy and gel permeation chromatography. The PTX-loaded NPs were prepared by a modified nanoprecipitation technique. The PTX-loaded NPs and PTX-loaded NPs@PDA were characterized in terms of size and size distribution, zeta potential, surface morphology, drug encapsulation efficiency, and drug release. Confocal laser scanning microscopy showed that coumarin-6-loaded NPs@PDA could be internalized by human melanoma cell line A875 cells. The cellular uptake efficiency of NPs was greatly enhanced after PDA modification. The antitumor efficacy of the PTX-loaded NPs@PDA was investigated in vitro by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and in vivo by a xenograft tumor model. The PTX-loaded NPs@PDA could significantly inhibit tumor growth compared to Taxol® and precursor PTX-loaded NPs. All the results suggested that the PTX-loaded MPEG-b-PCL NPs that had their surfaces modified with PDA are promising nanocarriers for malignant melanoma therapy.

Amplifying the molecular sieving capability of polyimide membranes via coupling of diamine networking and molecular architecture

The integration of molecular design with diamine modification generates synergistic effects for enhancing and fine tuning the molecular sieving potential of polyimide membranes. Polymer free volume and rigidity represent crucial conformational parameters that influence the effectiveness of diamine modification for elevating the H2/CO2 permselectivity of polyimide membranes. Experimental and molecular dynamics simulation results suggest that polyimides with higher intrinsic free volume and rigidity are ideal for diamine treatment, yielding greater increment in H2/CO2 selectivity. A series of copoly(4,4′-diphenyleneoxide/1,5-naphthalene-2,2′-bis(3,4-dicarboxylphenyl) hexafluoropropane diimide) (6FDA-ODA/NDA) membranes are modified with 1,3-diaminopropane (PDA). Polyimides with higher free volume intensify the methanol swelling effect which facilitates the transport and subsequent reaction of the diamine molecules. Gel content analyses of the PDA-modified films prove that the penetration depth of the diamine molecules and the extent of crosslinking are higher for polyimides with greater NDA content. 6FDA-NDA has the highest free volume and rigidity, thus exhibiting impressive improvement in ideal H2/CO2 selectivity from 1.8 to 120 after PDA modification. Conversely, 6FDA-ODA which is deficient in terms of free volume and rigidity, demonstrates a much lower increment in H2/CO2 selectivity from 2.5 to 8.2. The inherent heterogeneity of the PDA-modified polyimide films results in thickness-dependent gas permeability and selectivity. The potential of merging macromolecular tailoring with diamine networking to enhance the H2/CO2 separation performance of polyimide membranes is evident.