Mussel-inspired Polydopamine Research Articles

Mussel-inspired polydopamine-enabled in situ-synthesized silver nanoparticle-anchored porous polyacrylonitrile nanofibers for wound-healing applications

Wound dressing materials should be biocompatible, bactericidal, porous and mechanically strong. Moreover, the use of cost-effective and environmentally friendly materials is also important for developing wound dressing materials. However, developing scaffolds with all desired properties remains challenging. Herein, we have developed a porous polyacrylonitrile (PPAN) membrane modified by silver nanoparticles (AgNPs) with mussel-inspired polydopamine (PDA) assistance. Polydopamine (PDA) assisted in coating the antibacterial AgNPs uniformly in a size-controlled manner. Additionally, physiochemical properties such as the hydrophilicity and mechanical properties of the PAN membrane were enhanced. The resulting antibacterial membrane was tested for biocompatibility and antibacterial properties. The results showed that the AgNPs-functionalized membrane was biocompatible with fibroblast cells and had bactericidal effects on both gram-positive and gram-negative bacteria. In summary, this paper presents an approach for improving the physiochemical properties of cost-effective electrospun PAN membranes together with biocompatibility and targeted antibacterial properties.

Enzyme-Free Colorimetric Immunoassay for Protein Biomarker Enabled by Loading and Disassembly Behaviors of Polydopamine Nanoparticles

In this work, a mussel-inspired polydopamine (PDA) nanoparticle with biocompatible and reactive surface characteristics was desirably incorporated with high loading capacity and pH-induced disassembly-releasing behavior toward Fe(III) ions to develop an enzyme-free colorimetric immunoassay. The catechol functional network of PDA can act as a scaffold to coordinate with large amounts of Fe(III) ions to form the PDA-Fe(III) NPs whose coordination state can be tailored by changing the pH values. In detail, PDA-Fe(III) NPs can be maintained in a disassembled tri-coordinate state under alkaline conditions while the highly loaded Fe(III) ions can be easily released under acid conditions to react with ferrocyanide for the in situ generation of Prussian blue (PB) NPs. The detection sensitivity of prostate-specific antigen (PSA) was significantly improved, owing to the high peroxidase-like activity of PB NPs that triggered excellent catalytic effect by the colorimetric reaction. In addition, favorable linearity was found in the range of 0.0005-20 ng mL-1 with a low detection limit of 0.84 pg mL-1 (S/N = 3). Furthermore, excellent selectivity and reproducibility were exhibited by the developed enzyme-free colorimetric immunoassay. It is believed that this proposed PDA-Fe(III) NP-based enzyme-free colorimetric system will offer a facile and reliable tool for the sensitive detection of PSA and other cancer biomarkers in human serum.

Polydopamine Mediated Growth of Ag Nanostructures on ZnO Thin Films for Catalytic Degradation of Organic Dyes

In this study, multi-functional films were produced by the solution-phase growth of plasmonic Ag nanostructures (NSs) on ZnO fabricated by RF magnetron sputtering technique. The Ag NSs was grown on ZnO coated surface by functionalizing the thin film with mussel-inspired polydopamine. The structural analysis was performed by Grazing Incident X-ray diffraction (GIXRD) and Fouirer Transform Infrared Spectrometer (FTIR) technique in order to observe the effect of the Ag NSs deposition times. The effect of growth conditions on the structure and size of Ag NSs was investigated by Field Emission Scanning Electron Microscope (FESEM) imaging technique. The chemical compositions of as-deposited and Ag decorated ZnO films confirms using Energy-dispersive X-ray spectroscopy (EDX) analysis. The catalytic performance of the multi-functional films was investigated by the degradation of organic dyes (methyl orange (MO) and rhodamine B (RhB)).The catalytic activity of Ag on the is examined in details where it is found that maximum catalytic performance was observed within first 15 min for the ZnO thin films that were decorated with Ag NSs for 24h. The rate constant for the degradation reaction was 33.8x10-3 min-1 and 43.2x10-3 min-1 for MO and RhB, respectively. These results show the promise of integrating metal oxide films with plasmonic structures for efficient degradation of organic dyes.

Label-free SERS detection of Raman-Inactive protein biomarkers by Raman reporter indicator: Toward ultrasensitivity and universality

It is still challenging to sensitively detect protein biomarkers via surface-enhanced Raman scattering (SERS) technique owing to their low Raman activity. SERS tag-based immunoassay is usually applied; however, it is laborious and needs specific antibodies. Herein, an ultrasensitive and universal “Raman indicator” sensing strategy is proposed for protein biomarkers, with the aid of a glass capillary-based molecularly imprinted SERS sensor. The sensor consists of an inner SERS substrate layer for signal enhancement and an outer mussel-inspired polydopamine imprinted layer as a recognition element. Imprinted cavities have two missions: first, selectively capturing the target protein, and second, the only passageway of Raman indicator to access SERS substrate. Specific protein recognition means filling imprinted cavities and blocking Raman indicator flow. Thus, the quantity of captured protein can be reflected by the signal decrease of ultra-Raman active indicator molecule. The capillary sensor exhibited specific and reproducible detection at the level down to 4.1 × 10−3 μg L−1, for trypsin enzyme in as-received biological samples without sample preparation. The generality of the mechanism is confirmed by using three different protein models. This platform provides a facile, fast and general route for sensitive SERS detection of Raman inactive biomacromolecules, which offers great promising utility for in situ and fast point-of-care practical bioassay.

Reproducible and fast preparation of superhydrophobic surfaces via an ultrasound-accelerated one-pot approach for oil collection

The currently available superhydrophobic coating techniques that utilize mussel-inspired polydopamine coating to construct hierarchical superhydrophobic structures require multiply procedures and are time-consuming processes. Here, we propose an ultrasound-accelerated strategy to various commercial sponges with hierarchically structured superhydrophobic surfaces by briefly submerging sponges into a slightly alkaline aqueous mixture comprising dopamine hydrochloride (DA) and dodecyltrimethoxysilane (DTMS) under ultrasound. The ultrasound is found significantly accelerate the hierarchical surface structures from PDA, while only minorly influences the hydrolysis of DTMS that hydrophobically modifies the surface of PDA. As a result, the hierarchical superhydrophobic surfaces are formed within 25 min. In addition, the superhydrophobicity of the surface can be recovered by repeating this ultrasound-assisted process, provided that the superhydrophobic feature is vanished or lost during their use in a harsh environment. These superhydrophobic sponges are superior materials for oil collection from water, in a durably robust, efficient and recyclable manner with multi-life span. This strategy presents a rather high efficient and time-saving process for constructing/recovering hierarchical superhydrophobic surfaces, which may be useful for the rapid engineering commercial materials with restorable superhydrophobic surfaces.

Ca ions chelation, collagen I incorporation and 3D bionic PLGA/PCL electrospun architecture to enhance osteogenic differentiation

Bioactive synthetic scaffolds with 3D porous structure are the most attractive materials among various guided bone regeneration membranes. However, its osteogenic potential is still insufficient. This study was aimed to develop a Calcium surface-anchored Collagen I-PLGA/PCL scaffolds (PP/COL I-pDA-Ca) with enhanced osteogenicity. PP/COL I-pDA-Ca was electrospun from a collagen I-blended PLGA/PCL matrix and then modified by the chelation of Ca-ions via mussel-inspired polydopamine coating. PLGA/PCL, PLGA/PCL-polydopamine, PLGA/PCL-pDA chelated by Ca-ions were used as controls. Osteogenic effects of the scaffolds were examined using MC3T3-E1 cell culture. PP/COL I-pDA-Ca maintained 3D porous architecture with interconnected pores formed by randomly-oriented filamentous fibers and MC3T3-E1 cells cultured on it for 12 h or 24 h were more stretched and spread than those on the controls. PP/COL I-pDA-Ca significantly upregulated α10, α11 and β1 integrin expression after 48 h culture. ALP activity, OCN, OSX, BMP2 and RUNX2 expression of MC3T3-E1 cells cultured on PP/COL I-pDA-Ca scaffolds for 7 and 14 days were substantially enhanced when compared to controls (p < 0.05). The pDA-based Ca chelation, COL I incorporation and 3D bionic structure promoted cell adhesion and osteogenic differentiation of MC3T3-E1 cells. This novel PP/COL I-pDA-Ca scaffolds is an attractive alternative for guided bone regeneration.

Unique 3D interpenetrating capillary network of wood veneer for highly efficient cross flow filtration

Natural wood is mainly comprised of numerous long, partially aligned channels which are connected by micropores (such as ray cells, pits) providing high-efficiency nutrient transportation corridor. Here, thin wood veneer (the thickness of 400 μm) was used to design catalytic membrane for water treatment with reversed-tree transport pathways. As filtering direction is nearly perpendicular to wood growth direction, wood veneer possesses abundant sinuous water channels based on partially aligned and interconnected cell lumens which provide long enough micro reaction and suitable water transfer pathways in a greatly reduced thickness. Meanwhile due to a small rotary cutting angle, large number of incisions of vessels and fibers were formed ensuring large inlet area for fluid transport. And mussel-inspired polydopamine (PDA) was used to modify the surface of wood pores with highly active functional groups. Then, Pd nanoparticles could be in situ grown and immobilized onto wood channels via these groups (Pd/PDA/wood veneer). On account of the unique 3D interpenetrating capillary network structure, Pd/PDA/wood veneer shows a highly efficient water treatment for methylene blue (MB) solution. The flux of Pd/PDA/wood veneer can reach 3462 L/(m2h) with high MB removal efficiency (> 95%), meanwhile it shows good mechanical strength and flexibility. The designed thin wood veneer with unique structure exhibits promising results for practical wastewater treatment and even wider applications such as solar-thermal conversion, microreactor design.

Mussel-inspired polydopamine decorated pomelo peel as a durable biosorbent for adsorption of cationic dyes

In this work, an eco-firendly biosorbent was simply fabricated via self-polymerization of polydopamine on the porous pomelo peel. The composition and morphology of the obtained polydopamine modified pomelo peel (PP-PDA) were confirmed by Fourier transform infrared, emission scanning electron microscopy and Brunauer−Emmett−Teller surface area measurements, respectively. Next, the adsorption capacity of the PP-PDA towards various anionic and cationic dyes was investigated. Interestingly, the PP-PDA exhibited high adsorption capacity towards cationic dyes with the maximum adsorption capacities of 434.78 mg/g for methylene blue, 208.33 mg/g for neutral red and 143.88 mg/g for malachite green, respectively. Due to this adsorption feature, the PP-PDA can achieve selective adsorption of cationic dyes from mixtures. Meanwhile, the adsorption kinetics and adsorption isotherms of the PP-PDA towards cationic dyes obeyed pseudo-second-order kinetic and Langmuir isotherm model, respectively. Additionally, the results presented that the adsorption capacity of the PP-PDA increased with the increment of pH value of the aqueous solution, however, its adsorption capacity decreased with increasing of the salt concentration. Most importantly, the fabricated PP-PDA could be easily regenerated, its adsorption capacity could be maintained well even after twenty cycles. Therefore, the as-prepared PP-PDA can be employed as a promising biosorbent for dye-contaminated wastewater of treatment.

Mussel-Inspired Design of a Carbon Fiber-Cellulosic Polymer Interface toward Engineered Biobased Carbon Fiber-Reinforced Composites.

Tuning interactions at the interfaces in carbon fiber (CF)-reinforced polymer composites necessitates the implementation of CF surface modification strategies that often require destructive environmentally unfriendly chemistries. In this study, interfacial interactions in cellulose-based composites are tailored by means of a mussel-inspired adhesive polydopamine (PDA) coating, being inherently benign for the environment and for the structure of CFs. The step-by-step growth of PDA was followed by increasing treatment time leading to a hydrophilic PDA-coated surface, presumably via surface-based polymerization mechanisms attributed to strong π–π stacking interactions. Although PDA deposition led to an initial increase in the interfacial shear strength (IFSS) (5 h), it decreased at a longer reaction time (24 h), the formation of weakly attached PDA particles on the coated surface can possibly lie behind the latter phenomenon. Nevertheless, the mechanical properties of the prepared short CF-reinforced composite were improved (tensile strength increased ∼12% compared to the unmodified surface) with decreasing IFSS owing to the particular morphological design, resulting in longer fiber segments. Our study underlines the importance of the morphological design at the interface and considers PDA as a promising bioinspired material to tailor interfacial interactions.

Inkjet printing of dopamine followed by UV light irradiation to modify mussel-inspired PVDF membrane for efficient oil-water separation

Mussel-inspired polydopamine (PDA) modification of membrane is an effective alternative for improving permeation flux and anti-fouling performance. Meanwhile, efficient method for oil-water emulsions separation is still highly desired. However, problems, such as time-consuming process and low utilization ratio of expensive raw material, have always been stumbling block to application of this strategy. In this study, inkjet printing of dopamine (DA) followed by UV light irradiation to modify mussel-inspired polyvinylidene fluoride (PVDF) membrane was proposed. Accordingly, PVDF membrane was inkjet printed by alternately using DA inks and alkaline tris (hydroxymethyl) aminomethane (Tris) ink. The resultant membrane was then subjected to photopolymerization under UV irradiation to form a PDA layer. Successful formation of PDA layer on membrane surface was verified by series of physical and chemical methods. The optimized membrane (DA80-60/PVDF) exhibited superior oil/water separation performance with 1.5 times permeate flux higher than that of the pristine PVDF membrane and above 99% oil rejection rate. Meanwhile, the modified membranes showed satisfactory stability in aqueous solution with wide pH range (pH 2.0–7.0). The novel membrane modification method proposed in this study is facile, cost-saving and environment-friendly, serving as a competitive candidate for fabrication of efficient membranes for oil-water emulsion separation.

Advances in polydopamine surface modification for capillary electrochromatography

Capillary electrophoresis (CE) has a wide range of applications in analytical fields due to its advantages of low sample consumption, short separation time, and high separation efficiency. The cathodic electroosmotic flow (EOF) and single electrophoretic separation mechanism are not optimal for many CE applications. Hence, the use of an unmodified fused-silica capillary leads to insufficient separation performance that cannot meet the requirements for various complex sample systems, especially neutral and chiral compounds. Therefore, it is necessary to introduce various capillary modification strategies in CE so that its potential for practical application can be expanded. Mussel-inspired polydopamine (PDA) and PDA-derived coating materials have fascinating advantages such as simple surface coating procedures, strong surface adhesiveness, good chemical stability, latent reactivity with many functionalized molecules, and good biocompatibility. Thus, they have been widely utilized in different research fields, including catalysis, sensing, water treatment, sample pretreatment, biomedicine, chromatographic separation, and CE. The preparation of PDA coatings is simple as it involves physical adsorption, and the obtained surface adhesive coatings possess good stability similar to covalently bonded coatings. Therefore, PDA and PDA-derived coatings are well suited for the modification of fused-silica capillaries. More importantly, the PDA coating can be utilized as an intermediate reaction platform for diverse subsequent surface modification because of its strong surface adhesive property and strong latent reactivity with many functionalized molecules (such as polymers, proteins, and nanomaterials). Consequently, various chromatographic retention mechanisms can be introduced on the inner wall of the capillary, thereby contributing to the fabrication of multi-functional PDA-based stationary phases for CEC. Owing to these outstanding advantages, researchers are paying increasing attention to the great application potential of PDA and PDA-derived coatings in CEC. In this paper, recent advances in the methods for preparing PDA coatings, especially the recently developed fabrication strategies and various applications of PDA-modified silica capillary in open tubular-capillary electrochromatography (OT-CEC) and capillary electrochromatography monolithic columns, are summarized and discussed. Furthermore, the application prospects of PDA-based coating materials in CEC are prospected in this review. Although PDA and PDA-derived coating materials are seeing widespread utilization in field of CEC, researchers have still not reached a definite conclusion regarding the PDA formation and coating mechanisms, and further investigation is needed in this direction. The PDA coatings formed using existing methods are generally thin. In the early stage, many studies adopted the strategy of repeated coating to improve the coating effect of PDA in capillaries, but this method was found to be time-consuming and less efficient. In order to improve the preparation efficiency of PDA-modified CEC columns, many researchers have focused on fast deposition induced by a strong oxidant to obtain PDA-coated columns. However, the controllability of the PDA coating obtained by this method is poor. Thus, it is necessary to further explore new preparation strategies for PDA-coated CEC capillaries with better reproducibility and stronger operability. On the other hand, although a strategy for directly synthesizing functional PDA-coated CEC columns in the organic phase has been proposed, its application potential in CEC remains to be further explored. In addition, the PDA coating itself has poor porosity and a small specific surface area, which may be significantly improved by modifying the coating on the porous monolithic column surface. However, there has been limited research on the use of PDA coatings in monolithic columns, and their application potential remains to be expanded. With in-depth research into the formation mechanism and preparation methodologies of PDA coatings, PDA, which is a highly malleable biomimetic material, will play a more important role in advances in the fields of CE and CEC.

Direct attachment of suspension cells to PDA surface and its application in suspension-cell QCM biosensor

Mussel-inspired polydopamine (PDA) has been widely applied for functionalizing various material surfaces through a simple and versatile approach. Several studies have demonstrated the adhesion-promotion properties of the PDA surface for adherent cells. However, few reports are associated with suspension cells. In this study, the attachment property of suspension cells on the PDA surface was investigated for the first time, where we found that the suspension cells can be directly attached to the PDA coating without any secondary modifications. To exemplify the potential of this property, a PDA-based suspension-cell QCM biosensor was fabricated. The biosensor showed a high degree of repeatability and stability as well as low nonspecific binding to the irrelevant protein. The real-time and label-free evaluation of the binding of a diverse range of lectins on three different types of suspension cells indicated the variation of the glycosylation on these cell surfaces. Furthermore, the kinetic evaluation of the protein-carbohydrate interactions on the suspension cell surface was also performed. This work reports a new strategy for fabrication of PDA-based suspension-cell QCM biosensor via simple and efficient immobilization of suspension cells, which provides a simple way for the study of the complex molecular recognition on suspension cell surfaces.

Decoration of electrical conductive polyurethane-polyaniline/polyvinyl alcohol matrixes with mussel-inspired polydopamine for bone tissue engineering.

Electrospinning is a versatile technology for the fabrication of nanofibrous matrixes to regenerate defects. This study aims to develop a functionalized and electroconductive polymeric matrix to improve rat bone marrow mesenchymal stem cell adhesion, proliferation, and differentiation. Herein, the influence of the chemical composition of the substrate on homogeneous modification of the surface with mussel-inspired polydopamine (PDA) is focused. Accordingly, the deposition of PDA on the surface was proved by Fourier transform infrared spectroscopy. Morphologies of the scaffolds demonstrated homogeneous decoration of the polyvinyl alcohol (PVA)/polyurethane (PU)-polyaniline (PANI) matrixes with PDA, while a lower density of mussel-inspired polymer was observed in bare PU-PANI constructs. Although uniform and dense precipitation of PDA reduced conductivity of scaffolds 1.2 times compared with the samples with a low density of the PDA, 1.1 and 1.2 times enhancement in tensile strength and Young's modulus, respectively, were the strength of the applied process, especially in bone tissue engineering area. Contact angle measurements demonstrated about two times reduction in measured values, which shows improvement in hydrophilicity of PDA-modified PVA/PU-PANI fibers compared with PDA-coated PU-PANI ones. Swelling ratio and mass loss ratio calculations revealed enhancement in measured values as a function of homogeneous and dense coating, which arise from hydrophilicity of the polymeric substrate. The bioactivity test indicated that a dense layer of PDA strongly supports formations of hydroxyapatite-like crystals. Moreover, homogeneous decoration of conductive matrixes with PDA showed suitable cell viability, adhesion, and spreading while cell-scaffolds interactions improved under electrical stimulation. Higher expression of alkaline phosphatase and secretion of Collagen I under the electrical field proved the applicability of modified electroconductive scaffolds for further preclinical and clinical studies to introduce as a reconstructive bone substitute.

Solvothermal-assisted in situ rapid growth of octadecylamine functionalized polydopamine-based permanent coating as stationary phase for open-tubular capillary electrochromatography.

In recent years, mussel-inspired polydopamine (PDA) based materials have been widely used as stationary phases for open-tubular capillary electrochromatography (OT-CEC) because of their various excellent properties. Nevertheless, the traditional synthesis routes of functionalized PDA-based capillary columns usually are time-consuming and limited in aqueous solutions. Herein, we report a facile and rapid route to prepare octadecylamine (ODA) functionalized PDA coated OT-CEC columns in organic solvents via a novel one-step in situ solvothermal-assisted coating strategy. Through this developed solvothermal-assisted approach, the growth rate of ODA/PDA coating was significantly speeded up and their hybrid coating process on the capillary inner surface could be rapidly completed in 60min. The successful preparation of the solvothermal-assisted ODA/PDA hybrid coating were systematically characterized and confirmed by several methods. The influence of the preparation parameters on the formation of hybrid coating and the separation ability of the ODA/PDA modified columns were systematically explored. Consequently, the high-efficiency baseline separation of four kinds of neutral, acidic and basic analytes were achieved based on the ODA/PDA modified columns. The repeatability of the solvothermal-assisted ODA/PDA coated column was also studied, and the relative standard deviations for intra-day, inter-day and column-to-column were all less than 5%. Additionally, the solvothermal-assisted ODA/PDA modified column exhibited good stability and long lifetime.

Polydopamine coated poly(m-phenylene isophthalamid) membrane as heat-tolerant separator for lithium-ion batteries

Poly(m-phenylene isophthalamide) (PMIA) membranes are promising heat-tolerant separator candidates of lithium-ion batteries (LIBs), while their wettability toward carbonate electrolyte and corresponding batteries performance are not desirable. Herein, PMIA membranes coated with ultrathin mussel-inspired polydopamine (PDA) layer were fabricated as separators in LIBs. The introduced amino, quinonyl, and catechol groups in PDA coating could enhance the wettability of the resultant PMIA-PDA separator toward electrolyte. The PMIA-PDA separator had excellent thermal stability, showing a thermal shrinkage of 5.2% at 200 °C. The contact angle of the thermal-treated PMIA-PDA separator could maintain at 26.1°, which decreased by 42.7% compared with the pristine PMIA separator. The PMIA-PDA separator also displayed a high ionic conductivity (0.86 mS cm−1) and a low interfacial electric resistance (62.4 Ω). Consequently, the assembled LiCoO2/PMIA-PDA/Li battery achieved good cyclic stability with the capacity retention of 84.3% (121.1 mAh g−1) after 100 cycles under 30 °C. More significantly, the relevant capacity retention remained at 89.0% (127.5 mAh g−1) under 60 °C, which implied a great potential of PMIA-PDA membranes as separators of high-safety LIBs.

Mussel-Inspired Magnetic Nanoflowers as an Effective Nanozyme and Antimicrobial Agent for Biosensing and Catalytic Reduction of Organic Dyes.

Mussel-inspired chemistry has been embodied as a method for acquiring multifunctional nanostructures. In this research, a novel mussel-inspired magnetic nanoflower was prepared through a mussel-inspired approach. Herein, magnetic PDA–Cu nanoflowers (NFs) were assembled via incorporating magnetic Fe3O4@SiO2–NH2 core/shell nanoparticles (NPs) into mussel-inspired polydopamine (PDA) and copper phosphate as the organic and inorganic portions, respectively. Accordingly, the flower-like morphology of MNPs PDA–Cu NFs was characterized by scanning electron microscopy (SEM) images. X-ray diffraction (XRD) analysis confirmed the crystalline structure of magnetic nanoparticles (MNPs) and copper phosphate. Vibrating sample magnetometer (VSM) data revealed the superparamagnetic behavior of MNPs (40.5 emu/g) and MNPs PDA–Cu NFs (35.4 emu/g). Catalytic reduction of MNPs PDA–Cu NFs was evaluated through degradation of methylene blue (MB). The reduction of MB pursued the Langmuir–Hinshelwood mechanism and first-order kinetics, in which the apparent reduction rate Kapp of MB was higher than 1.44 min–1 and the dye degradation ability was 100%. MNPs PDA–Cu NFs also showed outstanding recyclability and reduction efficiency, for at least six cycles. Furthermore, the prepared MNPs PDA–Cu NFs demonstrated a peroxidase-like catalytic activity for catalyzing 3,3′,5,5′-tetramethylbenzidine (TMB) to a blue oxidized TMB (oxTMB) solution in the presence of H2O2. Antimicrobial assays for MNPs PDA–Cu and PDA–Cu NFs were conducted on both Gram-negative and Gram-positive bacteria. Moreover, we demonstrated how the existence of magnetic nanoparticles in PDA–Cu NFs influences the inhibition of an increasing zone. Based on the results, mussel-inspired magnetic nanoflowers appear to have great potential applications, including those relevant to biological, catalysis, and environmental research.

One-step, low-cost, mussel-inspired green method to prepare superhydrophobic nanostructured surfaces having durability, efficiency, and wide applicability

Various oils discharged from daily life and industrial production, as well as frequent oil spillages, have led to severe water pollution and ecological problems. Mussel-inspired polydopamine has been widely applied for fabrication of superhydrophobic materials for oil/water separation. However, the need of additional nanoparticles via tedious steps to construct nanostructures, and the high cost of dopamine itself limit its practical applications. Moreover, the application modes of superhydrophobic materials for oil/water separation are monotonous, which will limit the applied range of the superhydrophobic materials. For example, superhydrophobic sponge was usually used for adsorbing oil droplets or oil spills from water, while superhydrophobic fabric or mesh was usually used for separating bulk layered oil/water mixture. Therefore, developing simple and low-cost mussel-inspired surface modification strategy toward superhydrophobic materials, as well as diverse application modes for oil/water separation, is still highly desired. In this study, superhydrophobic sponge and fabric with nanostructures, which exhibits excellent performance for diverse oil/water separation, have been fabricated through a novel one-step and cost-effective mussel-inspired approach. The resultant superhydrophobic sponge exhibits outstanding oil absorption capability (weight gains up to 8860%), while the superhydrophobic fabric can effectively separate oil/water mixture. Moreover, diverse modes for oil/water separation have been developed for the first time. For example, water-in-oil emulsion can be highly-efficient separated by a compressed superhydrophobic sponge (~1800L m-2h−1 bar−1 for water-in-oil emulsion, and above 99% rejection rate for water droplets), while crude oil spills can be efficiently collected by a superhydrophobic boat (above 98%).

Mussel-inspired polydopamine functionalized recyclable coconut shell derived carbon nanocomposites for efficient adsorption of methylene blue

Relatively cheap or at no cost, easily available, renewable agricultural waste has been given a new purpose. Using coconut shells as the raw material, and being obtained from agricultural, industry by-products, or even waste materials were used as carbon resource. Acid etching coconut shells carbon (AC) rendered micro/nanoscale hierarchical structures and made the surface available for further modification. Then, the surface of acidified coconut shell carbon was engineered via mussel inspired chemistry. The polydopamine functionalized AC composites (AC-PDA) were applied for efficient removal of methylene blue (MB) dye. Further, the surface morphology, and chemical structure were evaluated by means of scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FT-IR). Through the combination of acid etching and mussel inspired chemistry, organic functional groups can be successfully introduced onto the surface of the coconut shells carbon. The improvement of adsorption capacity of AC-PDA compared with AC is probably due to the increased number of active binding sites resulting from surface modification and formation of new functional groups.

Taurine-Conjugated Mussel-Inspired Iron Oxide Nanoparticles with an Elongated Shape for Effective Delivery of Doxorubicin into the Tumor Cells.

Multifunctional iron oxide magnetic nanoparticles, among them nanorods, were prepared with a mussel-inspired polydopamine (pDA) surface coating agent for cancer therapeutics. Taurine, a free sulfur-containing ß amino acid, was grafted on the pDA at the iron oxide nanoparticle surface to enhance its biocompatibility and targeted delivery action. Doxorubicin (DOX), an anticancer drug, was loaded on the prepared nanovehicles with an entrapment efficiency of 70.1%. Drug release kinetics were then analyzed using UV–vis and fluorescence spectroscopies, suggesting the pH-responsive behavior of the developed nanovehicle. The developed system was then tested on PC-3 cell lines to check its cellular response. Confocal microscopy observations and (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) and Annexin V-FITC assays used to evaluate cell toxicity and apoptosis reveal a dose-dependent nature of nanorods and can overcome the side effects of using free DOX with a targeted action.

Corrosion resistance and biocompatibility of polydopamine/hyaluronic acid composite coating on AZ31 magnesium alloy

Magnesium (Mg) and its alloys have received widespread attention as implants for orthopedic surgery due to their degradability and appropriate mechanical properties. However, their poor corrosion resistance may lead to a decline of mechanical properties as well as changes in the surrounding microenvironment, which will eventually lead to their failure as implants. In this work, hyaluronic acid (HYA) was immobilized on AZ31 alloy via a mussel-inspired polydopamine (PDA) anchoring layer. The HYA layer closed the cracks caused by the PDA layer. In vitro corrosion behavior of the PDA/HYA composite coating was investigated via potentiodynamic polarization (PDP) and static immersion assay. The corrosion current density of PDA/HYA coating decreased from 8.48×10−5 A/cm2 to 5.71×10−6 A/cm2. During immersion, no obvious local alkalization was observed. Large amounts of calcium phosphate deposited on PDA/HYA coating, which enhanced the biological activity. MTT experiments show that the MC3T3-E1 cell survival rate of polydopamine coating exceeds 100% after cultivated for 5 days. It was found that the number of cells spreading on the surface of PDA/HYA composite coating was the most after the cell culture directly on the surface.