Oxidative Polymerization Of Dopamine Research Articles

Supramolecular Regulation of Polydopamine Formation by Amyloid Fibers.

Polydopamine (PD) and melanin species are chemically complex systems, the formation and properties of which are incompletely understood. Inspired by the role of functional amyloids in melanin biosynthesis, this paper examines the influences of the supramolecular structure of amyloids on oxidative polymerization of dopamine. Kinetic analyses on the formation of PD species in the presence of hen egg white lysozyme (HEWL) fibers or soluble HEWL revealed that both forms gave rise to the total quantity of PD species, but the rate of their formation could be accelerated only by the amyloid form. PD species formed with HEWL fibers showed a morphology of bundled fibers, whereas those with soluble HEWL had a mesh-like structure. Amyloid fibers of recombinant Pmel17 had properties similar to those of HEWL fibers in modulating PD formation. The results presented here suggest how nature designs functionality with an amyloid structure and can help understand and engineer chemistries of other functional amyloids.

Halloysite nanotubes@polydopamine reinforced polyacrylamide-gelatin hydrogels with NIR light triggered shape memory and self-healing capability

In this study, the polyacrylamide-gelatin composite hydrogels reinforced by halloysite nanotubes@polydopamine (HNTs@PDA) with NIR triggered shape memory performance and self-healing capacity were prepared through in-situ free radical polymerization of acrylamide in the mixture of Laponite-RD, HNTs@PDA and gelatin. HNTs@PDA was firstly synthesized through oxidative polymerization of dopamine on the surfaces of HNTs. HNTs@PDA was characterized by transmission electron microscopy, scanning electron microscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, Zeta potential, particle size analysis, and X-ray photoelectron spectroscopy. The photothermal performance of HNTs@PDA was then determined and the results reveal that HNTs@PDA can be employed as a superior photothermal agent to prepare light responsive hydrogels. The structure, morphology, mechanical properties, NIR triggered shape memory performance and self-healing capacity of the composite hydrogels were studied. The modified nanotubes act as cross-linking agent of polyacrylamide to form a rigid network in the hydrogel matrix, which leads to a significant increase in the mechanical properties. Moreover, the NIR triggered shape recovery process of the hydrogel is quite rapid, for example, it is only 63 s for recovering 720° shape change for the hydrogel of HNTs@PDA 40. The maximum NIR triggered healing efficiency of the hydrogels can reach 76%. The HNTs@PDA reinforced hydrogels with superior mechanical properties, NIR triggered shape memory, and self-healing ability exhibit promising applications in biomedical materials and smart engineering materials.

Removal of methylene blue via bioinspired catecholamine/starch superadsorbent and the efficiency prediction by response surface methodology and artificial neural network-particle swarm optimization

This paper demonstrates coupling of the artificial neural network (ANN) technique with the particle swarm optimization (PSO) method and compares the performance of ANN-PSO with response surface methodology (RSM) in prediction of the adsorption of methylene blue (MB) by a novel bio-superadsorbent. To this, a starch-based superadsorbent was synthesized using acrylic acid and acryl amid polymers and then catecholamine functional groups were combined onto the surface with oxidative polymerization of dopamine. The adsorption of MB was considered as a function of pH, dye concentration, and contact time. The best topology of the ANN was found to be 3-7-1, and prediction model of the adsorption capacity was demonstrated as a matrix of explicit equations. ANN-PSO is more accurate than RSM. The results revealed that the root-mean-square error, correlation coefficient, and normalized standard deviation for the ANN-PSO are 22.46, 0.99, and 16.83, respectively, while for RSM are 82.89, 0.98, and 65.41, respectively.

Deposition of Au nanoparticles on PDA-functionalized PVA beads as a recyclable catalyst for degradation of organic pollutants with NaBH4 in aqueous solution

A highly active and recyclable catalyst for the deposition of Au nanoparticles on the surface of polydopamine-functionalized poly(vinyl alcohol) macroporous beads was fabricated through the oxidative polymerization of dopamine and in-situ reduction route. The morphology and structure of PVA-PDA@Au beads were characterized using scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, X-ray power diffraction and N2 adsorption–desorption measurement. The as-prepared PVA-PDA@Au beads combined the advantages of PVA-PDA beads and Au NPs. PVA-PDA@Au beads exhibited enhanced catalytic activity towards the degradation of Rhodamine B (RhB) in the presence of NaBH4 with removal efficiency up to 99.5% in 5 min at an initial RhB concentration of 100 mg/L and a catalyst amount of 0.5 g/L. PVA-PDA@Au beads could be easily separated and recycled from the reaction system by simple filtration, and reused for the degradation of RhB in six consecutive cycles with a conversion of >99%. Moreover, the mechanism for the degradation of RhB by PVA-PDA@Au beads was proposed. In addition, the catalytic ability of PVA-PDA@Au beads was further studied to remove Tetrabromobisphenol A (TBBPA), in which approximately 100% TBBPA (initial concentration of 25 mg/L) was removed within 90 min. In practical application, RhB as a pollutant in river water was degraded rapidly by PVA-PDA@Au beads with removal efficiency higher than 94%. Thus, PVA-PDA@Au beads possessed high catalytic activity, fast reduction rate and good reusability as well as easy separation and simple preparation, endowing this catalyst with potential application prospect in the treatment of wastewater containing organic pollutants.

Nitrogen-doped carbon sheets coated on CoNiO2@textile carbon as bifunctional electrodes for asymmetric supercapacitors

Oxidative polymerization of dopamine and the subsequent thermal conversion generate N-doped carbon protective layers which could significantly improve the cycling stability of CoNiO2 electrodes.

Bioinspired catecholamine/starch composites as superadsorbent for the environmental remediation

Focusing on the encouraging properties of starch-based composite materials, starch‑g‑(acrylic acid‑co‑acrylamide) superabsorbent was synthesized using solution polymerization method, and then the catecholamine functional groups were introduced on to pore surface of the absorbent via oxidative polymerization of dopamine (DA). The adsorbent was optimized in terms of the monomers' mass ratio and synthesis conditions, and characterized by different characterization techniques. The polydopamine (PDA) coating thickness was estimated using transmission electron microscopy (TEM) image and it was found to be 83 nm. The bimodal mesoporous adsorbent with 5914.66% swelling ratio bearing micropores with a specific surface area of 2.8031 m2 g−1 was used for the adsorption of methylene blue (MB) as a model water pollutant dye. The maximum adsorption capacity was obtained 2276 mg g−1 at pH 9 and within 100 min. The adsorbent with unprecedented super high adsorption capacity can be encouraging from different environmental remediation points of view.

Novel Concept to Endow Poly(Methyl Methacrylate) Surfaces with Reactive Surface Groups

AbstractThe surface modification of poly(methyl methacrylate) (PMMA) moldings with poly(vinylamine) (PVAm) was performed to produce a novel composite material with a reactive surface, which can be subsequently functionalized to be (bio)compatible. The synthetic potential of the composite material was achieved by endowing the surface with a high density of primary amino groups. To graft the PVAm layer onto PMMA, an interlayer of polymerized dopamine (PDA) was deposited on the PMMA surface. This PDA layer acted as a reactive adhesion promoter. When varying the oxidizing agents, the oxidative polymerization of dopamine was extensively studied concerning deposition rate and homogeneity. Dess‐Martin periodinane possess a mean PDA deposition rate of 14.6 nm⋅h−1 and was the well suited oxidizing agent. The composite surfaces were characterized by atomic force microscopy (AFM), transmission electron microscopy (TEM), and X‐ray photoemission spectroscopy (XPS). The phenomenological surface properties were studied by electrokinetic measurements.

Fenton-Reaction-Derived Fe/N-Doped Graphene with Encapsulated Fe3C Nanoparticles for Efficient Photo-Fenton Catalysis

An excellent Fenton catalyst requires high activity, good stability and also convenience in separation for recycling. In this work we report Fenton-reaction-derived iron/nitrogen-doped graphene with encapsulated iron carbide nanoparticles (Fe3C@Fe/N-G) as an excellent heterogeneous Fenton catalyst. It was synthesized via Fe3+/H2O2-Fenton-reaction-driven oxidative polymerization of dopamine on graphene oxide surface, followed by carbonization process. Detailed characterizations unveil that as-prepared Fe3C@Fe/N-G is made up of Fe/N-doped graphene sheets with encapsulated dense and homogeneous Fe3C nanoparticles. Due to its unique microstructure and rationally-combined components, this catalyst exhibits appealing catalytic performance including high activity and excellent recoverability in photo-assisted Fenton reaction. This work may offer a valuable route to rational design and controllable synthesis of high-performance transition metal-based catalysts.

Potential of oxidative polymerization coating of cellulose nano-fiber by dopamine

In order to develop functional natural fiber reinforcements derived from cellulose nanofibers (CNF), surface modification of CNF by oxidative polymerization of dopamine was carried out. Resulting polydopamine (PDA)-coated CNF was blended with polypropylene (PP) to prepare the surface-modified CNF/PP nanocomposites. Obtained PDA-coated CNF and its nanocomposites were analyzed as to their morphologies, structures, and various properties. From analyses by Fourier transform infrared spectroscopy, scanning electron microscopy equipped with energy dispersive spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetry, it was clarified that the treated CNF surface was homogeneously coated by PDA without re-aggregation of CNF. Moreover, it was confirmed that the PDA-coated CNF/PP nanocomposites had excellent mechanical performances and good antistatic properties.

Polydopamine-assisted BMP-2 immobilization on titanium surface enhances the osteogenic potential of periodontal ligament stem cells via integrin-mediated cell-matrix adhesion

A mussel-inspired polydopamine (PDA), resulting from the oxidative polymerization of dopamine, was reported to be an attractive substrate for advancing biomaterial applications. Thus, this study determined the osteoconductive/osteoinductive properties of titanium (Ti) surfaces coated with PDA and the facilitation of the PDA layer to immobilize bone morphogenetic protein-2 (BMP-2) on Ti substrates. The surface chemistry of PDA or PDA/BMP-2-coated Ti was confirmed by contact angle measurement, scanning electron microscopy (SEM), immunofluorescence staining, atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). We verified the osteogenic potential of periodontal ligament stem cells (PDLSCs) cultured on the PDA or PDA/BMP-2-Ti surfaces. The osteogenic differentiation of the PDLSCs was assessed by measuring alkaline phosphatase (ALP) activity, intracellular calcium levels, as well as by evaluating osteocalcin (OCN), osterix (OSX), and runt-related transcription factor 2 (RUNX2) protein levels. The PDLSCs cultured on PDA/BMP-2-Ti showed the highest osteogenic activity compared with those on the control Ti and PDA-coated Ti surfaces. Moreover, PDLSCs on PDA and PDA/BMP-2-Ti expressed increased levels of integrin β1 and actin molecules compared to cells on control Ti. Blocking integrin β1 significantly decreased the osteogenic activity of PDLSCs on PDA/BMP-2 surfaces. This study suggests that the PDA coating can efficiently encourage the immobilization of BMP-2 on Ti surfaces and that this modified Ti substrate highly enhanced the osteogenic differentiation of PDLSCs by integrin-mediated cell-matrix adhesion mechanisms.

Fabrication of superparamagnetic nanofibrous poly(l-lactic acid)/γ-Fe2 O3 microspheres for cell carriers.

Nanofibrous poly(l-lactic acid) (PLLA) microspheres are extensively studied to be used as cell carriers in the field of tissue engineering because the unique structure can promote cell proliferation and migration. But as injectable scaffold materials, PLLA microspheres easily run off to the soft tissue space because of the lack of cohesive force. It will affect the treatment efficiency and even cause additional inflammatory response. In order to overcome this disadvantage, superparamagnetic γ-Fe2 O3 nanoparticles assisted with oxidative polymerization of dopamine were used for surface modification of PLLA microspheres in this study. The results showed that this surface modification had no obvious cytotoxicity, and the modified microspheres possessed the ability to carry seed cells to controllably move to the defect sites with the guidance of magnetic field, which may be able to increase the repair efficiency. Moreover, the characteristic nanofibrous structure was not destroyed after modification, which was able to promote biological activity of cells. This work provides a novel way to produce superparamagnetic nanofibrous microspheres designed for cell microcarriers. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2018. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 511-520, 2019.

Polydopamine-clay functionalized Calotropis gigantea fiber: A recyclable oil-absorbing material with large lumens

ABSTRACTA facile route was used for improving the oil-absorbing performance of Calotropis gigantea fiber (CGF) via a convenient oxidative polymerization of dopamine in the presence of attapulgite (APT) and subsequent instant immersion in an ethanolic solution of 1H,1H,2H,2H-perfluorooctyltriethoxysilane (PFS). The scanning electron microscope (SEM) coupled with element mapping indicated that the CGF had been successfully modified by polydopamine–APT–PFS, by which a roughened surface with higher contact angle against water can be formed. Consequently, the resulting fiber showed a significant enhancement in the oil-absorbing capacity, with 99.2 g/g for blend oil, 97.7 g/g for soybean oil, and 88.4 g/g for kerosene, respectively. Compared with previous methods, this approach is convenient for the construction of a novel material with tailored morphology and functionality, and the resulting fiber shows its promising application as a highly efficient and recyclable oil-absorbing material for oily wastewater treatment.

Mussel-inspired fabrication of konjac glucomannan/microcrystalline cellulose intelligent hydrogel with pH-responsive sustained release behavior

Intelligent hydrogels are attractive biomaterials for various applications, however, fabricating a hydrogel with both adequate self-healing ability and mechanical properties remains a challenge. Herein, a series of novel intelligent konjac glucomannan (KGM)/microcrystalline cellulose (MCC) hydrogels were prepared vis the mussel-inspired chemistry. MCC was firstly functionalized by the oxidative polymerization of dopamine, and the intelligent hydrogels were obtained by mixing aqueous solutions of KGM and functionalized MCC (PDMCC). By introducing PDMCC, a more compact interconnected porous structure formed for the resulting hydrogels. The self-healing ability and mechanical properties of intelligent hydrogels were dependence on the PDMCC content. Compared with KGM hydrogels, KGM/PDMCC hydrogels exhibited a more distinct pH sensitivity and a lower initial burst release, which was attributed to the compact structure and strong intermolecular hydrogen bond interaction between PDMCC and KGM. These results suggest that the KGM/PDMCC intelligent hydrogels may be promising carriers for controlled drug delivery.

Inner porous carbon nanofibers as binder-free electrodes for high-rate supercapacitors

In most of the porous carbon based electrode materials reported to date, the pores were open and directly exposed to electrolyte, and the materials suffered from a huge stress during long-term cycle at a large current density. These would inevitably cause an irreversible damage to the material structure, resulting in a dramatic capacity fade. In this work, the metal oxides composite nanofibers are first fabricated using an electrospinning technique, and then an oxidative polymerization of dopamine and a subsequent calcination are conducted to form a protecting shell. The inner carbon nanofibers have been obtained after removing the metal oxides nanoparticles. Owing to the robust dense carbon shell and inner porous carbon framework as well as intrinsic nitrogen doping, the prepared nanofibers electrode delivers high capacitances of 328 F g−1 at 1 A g−1 and 160 F g−1 even at an extremely high current density of 100 A g−1 in a 6 M KOH aqueous solution. The electrode maintains 77% of the initial capacity after 5000 cycles at 5 A g−1. The assembled symmetric supercapacitor exhibits a high capacitance of 97.9 F g−1 at 1 A g−1 and still maintains at 60 F g−1 even at a high current density of 50 A g−1. 73% of the initial capacitance is remained after 5000 cycles at a current density of 10 A g−1. The experimental results reveal that the inner porous carbon nanofibers may be a promising electrode material for high-rate supercapacitors.

Polydopamine Based Colloidal Materials: Synthesis and Applications.

Polydopamine is a synthetic analogue of natural melanin (eumelanin) produced from oxidative polymerization of dopamine. Owing to its strong adhesion ability, versatile chemical reactivity, biocompatibility and biodegradation, polydopamine is commonly applied as a versatile linker to synthesize colloidal materials with diverse structures, unique physicochemical properties and tunable functions, which allow for a broad scope of applications including biomedicine, sensing, catalysis, environment and energy. In this personal account, we discuss first about the different synthetic approaches of polydopamine, as well as its polymerization mechanism, and then with a comprehensive overview of recent progress in the synthesis and applications of polydopamine-based colloidal materials. Finally, we summarize this personal account with future perspectives.

Mussel-inspired nano-building block assemblies for mimicking extracellular matrix microenvironments with multiple functions

The assembly of nano-building blocks is an effective way to produce artificial extracellular matrix microenvironments with hierarchical micro/nano structures. However, it is hard to assemble different types of nano-building blocks, to form composite coatings with multiple functions, by traditional layer-by-layer (LbL) self-assembly methods. Inspired by the mussel adhesion mechanism, we developed polydopamine (PDA)-decorated bovine serum albumin microspheres (BSA-MS) and nano-hydroxyapatite (nano-HA), and assembled them to form bioactive coatings with micro/nano structures encapsulating bone morphogenetic protein-2 (BMP-2). First, PDA-decorated nano-HA (nano-pHA) was obtained by oxidative polymerization of dopamine on nano-HA. Second, BMP-2-encapsulated BSA microspheres were prepared through desolvation, and then were also decorated by PDA (pBSA-MS). Finally, the nano-pHA and pBSA-MS were assembled using the adhesive properties of PDA. Bone marrow stromal cell cultures and in vivo implantation, showed that the pHA/pBSA (BMP-2) coatings can promote cell adhesion, proliferation, and benefited for osteoinductivity. PDA decoration was also applied to assemble various functional nanoparticles, such as nano-HA, polystyrene, and Fe3O4 nanoparticles. In summary, this study provides a novel strategy for the assembly of biofunctional nano-building blocks, which surpasses traditional LbL self-assembly of polyelectrolytes, and can find broad applications in bioactive agents delivery or multi-functional coatings.

In vitro genotoxicity and cytotoxicity of polydopamine-coated magnetic nanostructures

Synthesis of magnetic nanoparticles and magnetic nanoclusters was performed by the co-precipitation method or solvothermal synthesis, respectively, followed by oxidative polymerization of dopamine, resulting in a polydopamine (PDA) shell. The nanomaterials obtained were described using TEM, FTIR and magnetic measurements.For the first time, cyto- and genotoxicity studies of polydopamine-coated nanostructures were performed on cancer and normal cell lines, providing in-depth insight into the toxicity of such materials. The tests conducted, e.g. ROS, apoptosis and DNA double-break of the nanomaterials obtained revealed the low toxicity of these structures. Thus, these results prove the biocompatibility and low genotoxicity of these materials and provide new data on the toxicity of PDA-coated materials, which is of great importance for their biomedical application.

One-Pot Synthesis of Fe(III)-Polydopamine Complex Nanospheres: Morphological Evolution, Mechanism, and Application of the Carbonized Hybrid Nanospheres in Catalysis and Zn-Air Battery.

We report one-pot synthesis of Fe(III)-polydopamine (PDA) complex nanospheres, their structures, morphology evolution, and underlying mechanism. The complex nanospheres were synthesized by introducing ferric ions into the reaction mixture used for polymerization of dopamine. It is verified that both the oxidative polymerization of dopamine and Fe(III)-PDA complexation contribute to the "polymerization" process, in which the ferric ions form coordination bonds with both oxygen and nitrogen, as indicated by X-ray absorption fine-structure spectroscopy. In the "polymerization" process, the morphology of the complex nanostructures is gradually transformed from sheetlike to spherical at the feed Fe(III)/dopamine molar ratio of 1/3. The final size of the complex spheres is much smaller than its neat PDA counterpart. At higher feed Fe(III)/dopamine molar ratios, the final morphology of the "polymerization" products is sheetlike. The results suggest that the formation of spherical morphology is likely to be driven by covalent polymerization-induced decrease of hydrophilic functional groups, which causes reself-assembly of the PDA oligomers to reduce surface area. We also demonstrate that this one-pot synthesis route for hybrid nanospheres enables the facile construction of carbonized PDA (C-PDA) nanospheres uniformly embedded with Fe3O4 nanoparticles of only 3-5 nm in size. The C-PDA/Fe3O4 nanospheres exhibit catalytic activity toward oxygen reduction reaction and deliver a stable discharge voltage for over 200 h when utilized as the cathode in a primary Zn-air battery and are also good recyclable catalyst supports.

Fabrication of magnetic alginate beads with uniform dispersion of CoFe2O4 by the polydopamine surface functionalization for organic pollutants removal

A simple and efficient method for production of magnetic composites by decorating CoFe2O4 with polydopamine (PDA) through oxidative polymerization of dopamine was conducted. Further, magnetic alginate beads with porous structure containing well-dispersed CoFe2O4-PDA were fabricated by ionic crosslinking technology. The resulting SA@CoFe2O4-PDA beads were characterized using scanning electron microscopy, Fourier transform infrared spectrometry, X-ray diffractometer, vibrating sample magnetometer and X-ray photoelectron spectroscopy. Adsorption potential of SA@CoFe2O4-PDA beads for organic dyes including Methylene Blue (MB), Crystal Violet (CV) and Malachite Green (MG) was evaluated. SA@CoFe2O4-PDA beads exhibited excellent adsorption performances due to the composite effect, large surface area and porous structure. Organic dyes could be removed from water solution with high efficiency in a wide pH range of 4.0–9.0. Moreover, it exhibited much higher adsorptivity towards MB and CV with the maximum adsorption capacities of 466.60 and 456.52mg/g, respectively, which were much higher than that of MG (248.78mg/g). Ca-electrolyte had obvious adverse effects on MB and CV adsorption than MG. FTIR and XPS demonstrated that carboxylate, catechol, hydroxyl and amine groups might be involved in adsorption of organic dyes. The characteristics of wide pH range, high adsorption capacity and convenient magnetic separation would make SA@CoFe2O4-PDA beads as effective adsorbent for removal of organic dyes from wastewater.

A novel electrodeposition route for fabrication of the superhydrophobic surface with unique self-cleaning, mechanical abrasion and corrosion resistance properties

Inspired by the adhesive proteins in mussels, a novel electrodeposition route has been developed to create multifunctional zinc (Zn)/polydopamine (pDop)/n-dodecyl mercaptan (NDM) composite coatings on different substrates, where oxidative polymerization of dopamine was simultaneously integrated during electrodeposition process. Hierarchical cauliflower-like structure was obtained on the electrodeposited Zn/pDop coatings. After modification with NDM, the prepared Zn/pDop/NDM coatings on different substrates (steel, Al and Cu) possessed excellent superhydrophobicity, exhibiting a maximum water contact angle (WCA) of 167.6° and a sliding angle (SA) less than 1° on the steel substrate. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) were employed to investigate the morphology and the chemical composition of the coatings. The mechanisms of electrodeposition process were discussed. The integrated electrodeposition and polymerization processes promised a synergistic effect on promoting the superhydrophobicity of coating. Results indicated that the dopamine greatly improved the mechanical abrasion resistance of the prepared superhydrophobic coatings. Additionally, these coatings demonstrated superior superhydrophobic stability, corrosion resistance and self-cleaning properties. It is believed that this novel and facile electrodeposition route for fabricating superhydrophobic coatings on various metallic materials will generate great impacts in practical applications.