Polymerization Of Dopamine Research Articles

Polydopamine-modified magnetic foam composites synergistically activate peroxymonosulfate with visible light for sulfadiazine degradation and oil–water separation

This study used a CuSO4/H2O2 catalyst to accelerate the oxidation and polymerization of dopamine in solution to facilitate the rapid deposition of polydopamine (PDA) onto a melamine foam. Dopamine provided the Fe3O4 adhesive layer and additional photocatalytic electron transfer channels for the foam. Stearic acid (SA) was used as the final incorporation on the surface of melamine foam(MF) to further superhydrophobically modify the magnetic foam (MF@PDA/Fe3O4) to obtain superhydrophobic magnetic MF@PDA/Fe3O4@SA foam. The foam has excellent capacity, acid resistance, alkali resistance, flame retardant, and salt resistance and can be conveniently separated, recycled, and recovered using magnetism. At the same time, peroxymonosulfate (PMS) can be activated to generate super-active radicals. Within 16 min, the degradation rate of sulfadiazine (SDZ) reached 99.8 %. Trapping experiments and EPR analysis confirmed the critical roles of ·OH, ·SO4− and 1O2 in SDZ removal. The wide pH working range (1.0 ∼ 13.0) and the slight toxicity of photocatalytic intermediates indicate that the as-prepared MF@PDA/Fe3O4@SA/PMS system has good application potential. The foam has potential practical applications in emergency oil spill rescue and oil/organic solvent wastewater treatment. Furthermore, this study provides a promising strategy for designing and fabricating a novel magnetic foam and photoactivated PMS synergistic system to eliminate pharmaceutical antibiotics effectively.

Paper-based biomimetic test-strip for CA15-3 with coloured readout

The combination of molecularly-imprinted polymers (MIPs) on paper substrates for capturing a cancer antigen 15–3 (CA15-3) with the traditional coloured transduction scheme of enzyme-linked immunosorbent assay (ELISA) using 3,3′,5,5′-tetramethylbenzidine (TMB), horseradish peroxidase (HRP) and H2O2 is presented here for the first time.Here, the paper surface was modified with a silane derivative containing an amine function that allows subsequent binding of 3-aminophenylboronic acid (3-APBA). The target protein, CA15-3, was then bound via the boronic groups of APBA. The empty space around CA15-3 was filled by polymerization of dopamine. Finally, the CA15-3 template was removed by breaking the imine function to create vacant sites for which CA15-3 has a high affinity. Binding of CA15-3 was detected by oxidation of TMB substrate by HRP in the presence of H2O2.The results showed that the MIP was able to selectively recognize CA15-3 within 3–500 U mL−1, even in complex samples. Quantitative data were extracted by analysing the colour coordinates of images captured with a smartphone using ImageJ. This selective behaviour was confirmed by comparison with a control material (non– polymer, NIP).Overall, the described approach has advantages over conventional ELISA, namely low cost and high stability, which is due to the use of MIP as a trapping element acting as a selective pre-concentration point of CA15-3. To our knowledge, this is the first biomimetic ELISA (B-ELISA) on paper substrate used for macromolecules such as proteins. We believe that this approach has the potential to be applied to other protein disease biomarkers, making it a suitable tool for screening glycoproteins at the point-of-care.

Dopamine as a polymerizable reagent for enzyme-linked immunosorbent assay using horseradish peroxidase

We demonstrate that dopamine can be used as a reagent for colorimetric enzyme-linked immunosorbent assay (ELISA) using horseradish peroxidase (HRP). Dopamine was able to be polymerized in the presence of HRP and H2O2, and black polydopamine was obtained after the enzymatic reaction. Because of the black color, the absorbance was significantly changed in the whole range of the visible light region. Here, an indirect competitive ELISA based on the polymerization of dopamine was performed to detect a fluoroquinolone antibiotic, enrofloxacin. The antibiotic is commonly used in livestock farming. The anti-antibiotics antibody was produced from egg yolk from chicken hens. In the visible range, sufficient absorbance changes of ∼0.4∼0.5 and a low background level for the ELISA response were obtained, and the 50 % inhibitory concentration value at 450 nm was determined to be 26 ppb. The performance of the indirect competitive ELISA based on the polymerization of dopamine was compared to that based on the oxidation of catechol because dopamine has a catechol skeleton. By the complex of HRP and H2O2, catechol can be oxidized to o-benzoquinone having a maximum absorption wavelength of 420 nm. It was shown that the absorbance change in the case of polydopamine was about 2.5 times higher than that of catechol, where the background levels were similar. This confirms that the polymerization of dopamine significantly enhanced the photosignal.

Insight into polydopamine coating on microfiltration membrane with controlled surface pore size for enhanced membrane rejection

Membrane modification with polydopamine (PDA) is a common practice to enhance membrane selectivity and improve membrane compatibility with nanoparticles or thin films. Depending on the membrane surface properties, dopamine can deposit or penetrate into microporous membranes, leading to alteration in the membrane's physicochemical properties and consequently its performance. In this study, microfiltration (MF) polyethersulfone membranes with varying surface pore sizes were fabricated by manipulating the precasting time (solvent evaporation time of 3s, 15s, 30s and 60s) prior to non-solvent induced phase separation (NIPS) process. Notably, the coating of PDA slightly reduced the membrane's surface pore size and membrane's porosity. M60 membrane which possessed the smallest mean surface pores (∼300 nm), exhibited PDA clusters predominantly formed on top of the membrane surface. With an increase in surface pore size, dopamine can penetrate the porous structure of the MF membrane, leading to the polymerization of dopamine into PDA aggregates on both the membrane surface and inner pores. The M30 membrane had the largest surface pore size (∼500 nm), showing the formation of large PDA globules in the finger-like pores. The membrane (M30P) experienced significant narrowing of the inner pores, resulting in reduced water permeability. Overall, all PDA-coated membranes exhibited improved sucrose rejection (85–95%) compared to the uncoated ones (64–83%). These finding provides insight into the polymerization mechanism of dopamine on porous membranes prior to the incorporation of nanomaterials or thin film coating.

COF-Coated Microelectrode for Space-Confined Electrochemical Sensing of Dopamine in Parkinson's Disease Model Mouse Brain.

Parkinson's disease (PD) is a progressive neurodegenerative disorder causing the loss of dopaminergic neurons in the substantia nigra and the drastic depletion of dopamine (DA) in the striatum; thus, DA can act as a marker for PD diagnosis and therapeutic evaluation. However, detecting DA in the brain is not easy because of its low concentration and difficulty in sampling. In this work, we report the fabrication of a covalent organic framework (COF)-modified carbon fiber microelectrode (cCFE) that enables the real-time detection of DA in the mouse brain thanks to the outstanding antibiofouling and antichemical fouling ability, excellent analytical selectivity, and sensitivity offered by the COF modification. In particular, the COF can inhibit the polymerization of DA on the electrode (namely, chemical fouling) by spatially confining the molecular conformation and electrochemical oxidation of DA. The cCFE can stably and continuously work in the mouse brain to detect DA and monitor the variation of its concentration. Furthermore, it was combined with levodopa administration to devise a closed-loop feedback mode for PD diagnosis and therapy, in which the cCFE real-time monitors the concentration of DA in the PD model mouse brain to instruct the dose and injection time of levodopa, allowing a customized medication to improve therapeutic efficacy and meanwhile avoid adverse side effects. This work demonstrates the fascinating properties of a COF in fabricating electrochemical sensors for in vivo bioanalysis. We believe that the COF with structural tunability and diversity will offer enormous promise for selective detection of neurotransmitters in the brain.

Sub-femtomolar capacitance-based biosensing of kanamycin using screen-printed electrodes coated with redox-active polymeric films.

Anultrasensitive capacitance-based biosensor has been developedcapable of detecting the kanamycin (KAN) antibiotic at sub-femtomolar levels. The biosensor was constructed using a potential-pulse-assisted method, allowing for the layer-by-layer deposition of a melanin-like polymeric film (MLPF) on an electrode surface modified with gold nanoparticles (AuNPs). The MLPF was formed through the electrochemical polymerization of dopamine and the specific kanamycin aptamer. By optimizing the operating parameters, we achieved a label-free detection of kanamycin by monitoring the variation of pseudocapacitive properties of the MLPF-modified electrode using electrochemical impedance spectroscopy. The developed biosensor demonstrated a wide linear response ranging from 1 fM to 100pM, with a remarkable limit of detection of 0.3 fM (S/N = 3) for kanamycin. Furthermore, the biosensor was successfully applied to detect kanamycin in milk samples, exhibiting good recovery. These findings highlight the promising potential of the aptasensor for determination of antibiotic residues and ensuring food safety. In conclusion, our ultrasensitive capacitance-based biosensor provides a reliable and efficient method for detecting trace amounts of kanamycin in dairy products. This technology can contribute to safeguarding consumer health and maintaining high food safety standards.

Killing two birds with one stone: A therapeutic copper-loaded bio-patch promoted abdominal wall repair via VEGF pathway.

Hernia and life-threatening intestinal obstruction often result from abdominal wall injuries, and the regeneration of abdominal wall defects is limited due to the lack of biocompatible, antibacterial and angiogenic scaffolding materials for treating injured tissues. Taking inspiration from the facile preparation of dopamine polymerization and its surface modification technology, in this study, multi-therapeutic copper element was introduced into porcine small intestinal submucosa (SIS) bio-patches through polydopamine (PDA) deposition, in order to regenerate abdominal wall injury. In both in vitro antibacterial assays, cytocompatibility assays and in vivo abdominal wall repair experiments, the SIS/PDA/Cu bio-patches exhibited robust antibacterial efficiency (＞99%), excellent biocompatibility to cells (＞90%), and enhanced neovascularization and improved collagen maturity compared to other commercially available patches (3.0-fold higher than the PP mesh), due to their activation of VEGF pathway. These findings indicated the bio-patch was a promising application for preventing visceral adhesion, bacterial infection, and promoting soft tissue regeneration.

Polarity Conversion of the Ag2S/AgInS2 Heterojunction by Radical-Induced Positive Feedback Polydopamine Adhesion for Signal-Switchable Photoelectrochemical Biosensing.

Efficient tuning of the polarity of photoactive nanomaterials is of great importance in improving the performance of photoelectrochemical (PEC) sensing platforms. Herein, polarity of the Ag2S/AgInS2 heterojunction is converted by radical-induced positive feedback polydopamine (PDA) adhesion, which is further employed to develop a signal-switchable PEC biosensor. In the nanocomposites, Ag2S and AgInS2 achieve electron-hole separation, exhibiting a strong anodic PEC response. Under the irradiation of light, the Ag2S/AgInS2 heterojunction is able to produce superoxide radical and hydroxyl radical intermediate species, leading to the polymerization of dopamine (DA) and the subsequent adhesion of PDA onto the Ag2S/AgInS2 heterojunction (Ag2S/AgInS2@PDA). By constructing a new electron-transfer pathway with PDA, the polarity of the Ag2S/AgInS2 heterojunction is converted, and the PEC response changes from anodic to cathodic photocurrents. In addition, since the photoreduction activity of PDA is stronger than that of the Ag2S/AgInS2 heterojunction, more superoxide radical can be produced by Ag2S/AgInS2@PDA once PDA is generated, thereby promoting the generation of PDA. Consequently, a positive feedback mechanism is established to enhance the polarity conversion of the Ag2S/AgInS2 heterojunction and amplify the responding to DA. As a result, the bioanalytical method is capable of sensitively quantifying DA in 10 orders of magnitude with an ultralow limit of detection. Moreover, the applicability of this biosensor in real samples is identified by measuring DA in fetal bovine serum and compared with a commercial ELISA method. Overall, this work offers an alternative perspective for adjusting photogenerated carriers of nanomaterials and designing high-performance PEC biosensors.

A surface multiple imprinting layers membrane with well-oriented recognition sites for selective separation of chlorogenic acid from Ficus carica L.

Chlorogenic acid (CGA), known as an important natural antioxidative compound in Ficus carica L, has valuable application prospects on health food, functional food, nutrition and dietary formulations. In this study, a surface multiple imprinting layers membrane (SMILM) was developed and applied to separate CGA from F. carica. Two different imprinting layers were integrated onto the membrane surface in sequence. The first imprinting layer was formed by dopamine polymerization and the second imprinting layer was fabricated by atom transfer radical polymerization (ATRP) and boronate affinity. The prepared SMILM with well-oriented multiple recognition sites exhibited high adsorption capacity (52.08 mg·g−1 in 60 min) for CGA and specific selectivity with imprinting factor (IF) of 3.06. Furthermore, the recognition mechanism of SMILM was clarified by molecular simulation and NMR. The SMILM was successfully applied to separate CGA from the fruits, peels and leaves of F. carica with recoveries of 90.22, 83.31 and 84.95 %, respectively.

Facile Synthesis of Basic Copper Carbonate Nanosheets for Photoacoustic Imaging-Guided Tumor Apoptosis and Ferroptosis and the Extension Exploration of the Synthesis Method.

Elimination of tumor cells using carbonate nanomaterials with tumor microenvironment-responsive capacity has been explored as an effective strategy. However, their therapeutic outcomes are always compromised by the relatively low intratumoral accumulation and limited synthesis method. Herein, a novel kind of basic copper carbonate nanosheets was designed and prepared using a green synthesis method for photoacoustic imaging-guided tumor apoptosis and ferroptosis therapy. These nanosheets were synthesized with the assistance of dopamine and ammonium bicarbonate (NH4HCO3) and the loading of glucose oxidase (GOx). NH4HCO3 could not only provide an alkaline environment for the polymerization of dopamine but also supply carbonates for the growth of nanosheets. The formed nanosheets displayed good acid and near-infrared light responsiveness. After intercellular uptake, they could be degraded to release Cu2+ and GOx, generating hydroxyl radicals through a Cu+-mediated Fenton-like reaction, consuming glucose, up-regulating H2O2 levels, and down-regulating GSH levels. Tumor elimination could be achieved by hydroxyl radical-induced apoptosis and ferroptosis. More amusingly, this synthesis method can be extended to several kinds of mono-element and multi-element carbonate nanomaterials (e.g., Fe, Mn, and Co), showing great potential for further tumor theranostics.

A chemodynamic nanoenzyme with highly efficient Fenton reaction for cancer therapy

Chemodynamic therapy (CDT) is a rising technology for cancer therapy by converting intracellular hydrogen peroxide (H2O2) into hydroxyl radical (•OH) via transition-metal-containing nanoparticles (NPs) catalysis reaction (i.e. Fenton reaction) to kill tumor cells. Highly efficient Fenton reaction and favorable delivery of the catalytic NPs ‘nanoenzyme’ are the key for successful treatment of cancer. In this work, we developed a novel nanoenzyme MnFe2O4@GFP for in vitro and in vivo antitumor therapy. A new MnFe2O4 nanoparticle containing two transition-metal-element Fe and Mn was synthesized for enhanced Fenton reaction and used to co-deliver protein with high biocompatibility through post-modification with dopamine polymerization, green fluorescent protein adsorption, and PEG coating. The enrichment of H2O2 and glutathione (GSH) in tumor tissue provided a favorable microenvironment for in situ generation of toxic free radicals. Fe3+ and GSH triggered a redox reaction to produce Fe2+, which in turn catalyzed H2O2 into •OH, with the consumption of antioxidant GSH. By combining Fe3+ with another catalyzer, the catalytic efficiency of the nanoenzyme were greatly improved. Consequently, the nanoenzyme showed efficient antitumor ability both in vitro and in vivo. Thus, the multifunctional CDT nanoenzyme platform shows great promising for antitumor therapy through the combination of catalyzers Fe3+ and Mn2+ and codelivery of protein cargo.

Oxygen-generating tissue adhesives via CaO2-mediated oxygen generation and in situ catechol oxidation for wound management

Bioinspired catechol amines, such as dopamine (DA), have been widely utilized as tissue adhesives for wound management. However, the development of DA-based adhesives is still challenging owing to the slow oxidation rate and low conjugation efficacy to the polymer backbone. Herein, we report on a new type of DA-incorporating and oxygen-generating tissue adhesive via a calcium peroxide (CaO2)-mediated crosslinking reaction for wound management. Gelatin-based oxygen-generating tissue adhesives (GOT) are fabricated through CaO2-mediated oxygen generation and facilitated in situ DA polymerization. These GOT hydrogels exhibit controllable gelation and mechanical properties with strong tissue adhesiveness (15–38 kPa). Moreover, the adhesive matrices rapidly generate oxygen up to 70% pO2 and provide transient hyperoxic conditions in vitro and in vivo. Interestingly, we demonstrate that the GOT hydrogels facilitated skin wound healing with enhanced neovascularization, hemostasis, and wound closure. In summary, we suggest that our GOT hydrogel is a promising bioactive tissue adhesive for wound management and tissue regeneration.

Surface mineralization with controlled polymerization of dopamine

AbstractPolydopamine (PDA) has been utilized as a scaffolding for various biomedical applications since its discovery. This versatility arises from the unique property of PDA to coat virtually any surface and its high biocompatibility. In this study, PDA has been used to synthesize calcium phosphate in simulated body fluid on surfaces that normally could not form these mineral layers. PDA has the potential to reduce calcium phosphate. Due to its natural hydrophilicity and the high density of charged surface groups. Adjusting the reaction conditions has been shown to alter the properties of the PDA coatings and in turn the applications. In this study, we will observe how controlling the reaction conditions to adjust properties of PDA can alter the mineral layer formed on the polymer surface. By maximizing the surface area of the polymer, the number of polar groups on the surface available to bind the mineralization. We will illustrate both the degree of mineralization on the surface as well as the chemical content of the minerals. We will illustrate that the ability of PDA to form calcium phosphate can be enhanced to allow for better biocompatibility for biomedical implants.

Cooperative regulation of hard template and emulsion self-assembly to the synthesis of N/O co-doped mesoporous hollow carbon nanospheres for supercapacitors

Hollow carbon nanospheres have attracted more and more attention as supercapacitor materials due to their excellent electrical conductivity, high theoretical surface area, high accumulation and rapid ion transfer and diffusion. In this work, we employed the Stöber method to create silica as a template, and then applied self-assembly and dopamine polymerization on the surface of the template to form SiO2@TMB-F127-PDA micelles. Then the nitrogen-doped mesoporous hollow carbon nanospheres (N-MHCNs) were prepared by carbonization and etching on the formed carbon precursors. The effect of dopamine amount on the structure and properties of N-MHCNs was systematically studied. Microstructural characterization results reveal that the morphology of N-MHCNs can be changed from sheet to sphere, and the particle size of N-MHCNs can be 33.8–225.7 nm, the specific surface area is distributed in the range of 175.9–430.1 m2 g−1. Due to the N,O heteroatomic co-doping and Porous spherical structure (with a small particle size of 33 nm, and a large specific surface area of 430.1 m2 g−1), typical sample N-MHCNS-2 shows excellent electrochemical performance in supercapacitors. And it has the highest specific capacitance (241 F g−1) at 0.5 A g−1 current density, excellent rate performance (capacity retention rate of 79 % when current density increases from 0.5 to 10 A g−1) and good cycling ability (capacity retention rate of 90.4 % after 3000 cycles), indicating that it shows great potential in energy storage. This approach provides new opportunities for the controllable synthesis of hollow mesoporous nanospheres and it can be extended to other systems such as hollow metals, metal oxide nanomaterials and carbon-based hybrids.

Insight into the Antioxidant Activity of 1,8-Dihydroxynaphthalene Allomelanin Nanoparticles.

Melanins are stable and non-toxic pigments with great potential as chemopreventive agents against oxidative stress for medical and cosmetic applications. Allomelanin is a class of nitrogen-free melanin often found in fungi. The artificial allomelanin obtained by the polymerization of 1,8-dihydroxynaphthalene (DHN), poly-DHN (PDHN), has been recently indicated as a better radical quencher than polydopamine (PDA), a melanin model obtained by the polymerization of dopamine (DA); however, the chemical mechanisms underlying this difference are unclear. Here we investigate, by experimental and theoretical methods, the ability of PDHN nanoparticles (PDHN-NP), in comparison to PDA-NP, to trap alkylperoxyl (ROO•) and hydroperoxyl (HOO•) radicals that are involved in the propagation of peroxidation in real conditions. Our results demonstrate that PDHN-NP present a higher antioxidant efficiency with respect to PDA-NP against ROO• in water at pH 7.4 and against mixed ROO• and HOO• in acetonitrile, showing catalytic cross-termination activity. The antioxidant capacity of PDHN-NP in water is 0.8 mmol/g (ROO• radicals quenched by 1 g of PDHN-NP), with a rate constant of 3 × 105 M-1 s-1 for each reactive moiety. Quantum-mechanical calculations revealed that, thanks to the formation of a H-bond network, the quinones in PDHN-NP have a high affinity for H-atoms, thus justifying the high reactivity of PDHN-NP with HOO• observed experimentally.

Mussels-inspired design a multi-level micro/nano re-entrant structure amphiphobic PVDF membrane with robust anti-fouling for direct contact membrane distillation

Membrane distillation has been widely used for effluent purification as a promising desalination technology, however, severe inorganic and organic fouling has typically hindered its practical large-scale application. In this study, we developed a facile strategy for fabricating an amphiphobic polyvinylidene fluoride(PVDF) membrane with a slippery surface. First, a bioinspired adhesive based on a polydopamine (PDA) layer is deposited on the membrane surface as an intermediate layer, providing an active anchor for nanoparticles (NPs). Subsequently, micro/nano SiO2 particles were in-situ grown on the membrane surface using the sol-gel method to construct the re-entrant structure, which was then fluorinated with 17-chain fluorosilane (17-FAS). The intermediate layer inspired by dopamine polymerization significantly improved the stability of SiO2 Nanoparticles. The amphiphobic membrane has a unique multi-level micro/nano re-entrant structure that provides a robust repellent ability against contaminants. The resultant amphiphobic membrane exhibited contact angles of 164o against water and 113o against oil, as well as a low sliding angle of 4.3o, demonstrating excellent water and organic matter repellency. Although the initial flux of the amphiphobic membrane is lower than that of the pristine membrane. The amphiphobic membrane exhibited comprehensive anti-fouling and anti-wetting properties with steady flux and significant salt rejection in the desalination process when CaSO4 and HA were added to the brine feed. This suggests that the modified amphiphobic membrane has a promising potential for long-term direct contact membrane distillation (DCMD) practical application.

A general dopamine deposition strategy on polyether sulfone membrane for water purification

As a biomass green material, polydopamine (PDA) shines in the field of water purification driven by solar energy with its strong adhesion and photoheating properties, but it is hard for PDA in tris solution to deposit on Polyether sulfone (PES) to obtain thick coating. To solve the problem, 3-aminopropyltriethoxysilane (AMEO) was chosen to modify PDA, and two-solvent strategy (alcohol/water) was applied. In this work, AMEO plays two roles: 1) catalyze the polymerization of dopamine (like tris solution); 2) improve the interaction between PDA and PES. In order to prove the universality of this strategy, the influence of the mixed ratio of three organic solvents (ethanol, methanol, isopropyl alcohol) and water on the deposition process was investigated. It was found that different alcohol/water mixed systems showed similar trends in polymerization rate and deposition amount. PES/PDA-AMEO (100 μL) with ethanol/water mixed ratio of 7:3 could achieve large deposition amount and relatively uniform surface. Under one sun irradiation (1 kWm−2), the water evaporation rate of the optimal PES/PDA-AMEO can reach 1.57 kgm−2h−1. Even for high concentration saltine water, the water evaporation rate is up to 1.05 kgm−2h−1. In addition, PES/PDA-AMEO obtained by this strategy can effectively intercept seawater salt and heavy metal ions, and the content of the distilled components meet the standards of potable water. Notably, this deposition strategy is expected to assist the uniform deposition of nanoparticles on PES to achieve the functionalization of the coating.

In situ growth of polydopamine modified ZIF-L arrays on air-laid paper as flexible evaporator for efficient solar desalination

The utilization of solar vapor generation for water purification plays a pivotal role in addressing the severe water scarcity crisis. However, it poses challenges due to inefficient light trapping and absorption limitations in solar thermal energy conversion. Here, we have strategically developed an array structured light trapping system with vertically grown, leaf-like zeolitic imidazolate framework (ZIF-L) nanosheets on flexible air-laid paper, accompanied by the catalytic effect of Co ions that result in oxidative polymerization of dopamine (DA) into pleated polydopamine (PDA) layers. This novel solution extends the propagation path of light in the trapping system through multiple scattering. Upon optimization, the P/ZIF-L@PDA-3 evaporator boasts an evaporation rate of 1.48 kg m−2 h−1 at 1 sun (1 kW m−2) irradiation and achieves an impressive solar vapor conversion efficiency of 94.5 %. In practical settings, the evaporation rate can reach 2.22 kg m−2 h−1 after 9 h with an average outdoor light intensity of 0.995 kW m−2. Our study presents an innovative approach to constructing a flexible evaporator with a light-trapping structure, providing immense potential for practical solar applications.

Investigation of the catalytic effect of defective Ni-MOF-74 on polymerization of dopamine and multi-pore polydopamine photothermal coating constructed with defective Ni-MOF-74 particles

Photothermal coating is an effective way to convert the seawater into fresh water, which is controlled by the light utilization capacity and micro-channel for the vaporation of water. In order to improve the effect of water evaporation and water purification driven by sunlight, polydopamine (PDA) coating with more micro-channel and high bonding was formed through the introduction of porous material and 3-Aminopropyltriethoxysilane (AMEO). Compared with Ni-MOF-74, defective Ni-MOF-74 could produce more coordination with dopamine and promote the polymerization of dopamine, resulting in the formation of sea cucumber structure, which is foundation for the micro-channel of the deposition coating of PDA. Also, depending on the sea cucumber structure, the as-prepared coating of PES/PDA/MOF-30 mg by the two-solvent strategy possesses the water evaporation rate of 1.85 kg/(m2·h), the photothermal conversion efficiency of 98.4%, the retention rate of alkali metal and heavy metal ions above 99% and good long-term stability. The coating with good comprehensive property is good choice for the water purification.

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

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