Oxidative Polymerization Of Dopamine Research Articles

The dual nature of biomimetic melanin.

Melanin-inspired nanomaterials offer unique photophysical, electronic and radical scavenging properties that are widely explored for health and environmental preservation, or energy conversion and storage. The incorporation of functional melanin building blocks in more complex nanostructures or surfaces is typically achieved via a bottom-up approach starting from a molecular precursor, in most cases dopamine. Here we demonstrate that indeed, the oxidative polymerization of dopamine, for the synthesis of melanin-like polydopamine (PDA), leads to the simultaneous formation of more than one nanosized species with different compositions, morphologies and properties. In particular, a low-density polymeric structure and dense nanoparticles (NP) are simultaneously formed. The two populations could be separated and analyzed in real time using a chromatographic technique free of any stationary phase (flow field fractionation, FFF). The results following the synthesis of melanin-like PDA showed that the NP are formed only during the first 6 hours as a result of a supramolecular self-assembly-driven polymerization, while the formation of the polymer continues for about 36 hours. The two populations were also separated and characterized using TEM, UV-vis absorption spectroscopy, fluorescence and light scattering spectroscopy, DLS, FTIR, ζ-potential measurements, gel electrophoresis and pH titrations. Interestingly, very different properties between the two populations were observed: in particular the polymer contains a higher number of catechol units (8 mmol g-1 -OH) with respect to the NP (1 mmol g-1 -OH) and presents a much higher antioxidant activity. The attenuation of light by NP is more efficient than that by the polymer especially in the Vis-NIR region. Moreover, while the NP scatter light with an efficiency up to 27% they are not fluorescent, and the polymer does not scatter light but shows an excitation wavelength-dependent fluorescence typical of multi-fluorophoric uncoupled systems.

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.

Oxidative Polymerization of 3,4-Dihydroxybenzylamine─The Lower Homolog of Dopamine.

Polydopamine (PDA) formed by oxidative polymerization of dopamine has attracted wide interest because of its unique properties, in particular its strong adhesion to almost all types of surfaces. 3,4-Dihydroxybenzylamine (DHBA) as the lower homolog of PDA also contains a catechol unit and an amino group and thus can be expected to exhibit a similar adhesion and reaction behavior. In fact, autoxidation of DHBA with air in 2-amino-2-hydroxymethyl-propane-1,3-diol (Tris) buffer gives rise to deeply colored oligomer/polymer products (poly(3,4-dihydroxybenzylamine) (PDHBA)) that strongly adhere to several surfaces. Here, the material is characterized by solid-state NMR spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), electron spin resonance (ESR) spectroscopy, mass spectrometry, and atomic force microscopy (AFM). Reaction pathways were rationalized taking into consideration the analytical results that show similarity to PDA chemistry, but also considering differences, leading to a more complex reaction behavior and thus to new structures not found in PDA.

Anisotropic α-Fe2O3/AgAu/Polydopamine Nanostructures for Photothermally Enhanced Antibacterial Applications

Multifunctional photothermal nanomaterials offer notable opportunities for antimicrobial therapy due to their excellent antibacterial activities without leading to drug resistance. Herein, we report a facile one-step strategy for fabricating anisotropic corn-like α-Fe2O3/AgAu/polydopamine (PDA) nanospindles with photothermally enhanced antibacterial performance. The AgAu bimetallic nanocrystals sandwiched between the α-Fe2O3 core and the PDA shell are achieved by simultaneous reduction from AgNO3 and HAuCl4 during the oxidative polymerization of dopamine and galvanic replacement reaction between the obtained Ag nanocrystals and Au precursor. The inner nanostructure and atom ratio of AgAu bimetallic nanocrystals can be modulated by varying the experimental parameter, thus further controlling the photothermal activities. In comparison to α-Fe2O3/Au/PDA, Fe2O3/Ag1.7Au0.8/PDA (50 μg/mL) has a better photothermal conversion effect (60.69%). Moreover, the α-Fe2O3/Ag1.7Au0.8/PDA nanospindle exhibits moderate antibacterial activity, which may be derived from Ag+ release. Under application of near-infrared light irradiation, the corn-like α-Fe2O3/Ag1.7Au0.8/PDA nanospindles (50 μg/mL) exhibit a photothermally enhanced sterilization effect against both Escherichia coli and Staphylococcus aureus (99.99%). This “Ag+ release–photothermal” coupling sterilization method provides a simple synergistic antimicrobial therapy strategy, which possesses great promise for future nanomedicine against bacteria in water treatment.

Biomimetic electrospinning for fabrication of poly(lactic acid)/graphite oxide/poly(dopamine) nanofiber membrane

As a new preparation process of nanofibers, electrospinning technology developed by bionic spider spinning can further improve the molecular structure and mechanical properties of nanofibers, and obtain nanofibers and base membrane products with better mechanical properties. The spider spinning needs minimal energy consumption though it has a very long liquid transport tube. Because spider silk has high mechanical properties and wide industrial applications, so a kind of new biomimetic electrospinning technology which harnessed a very long spiral-needle was proposed. Then poly(lactic acid)PLA/graphite oxide(GO)/dopamine (DA) nanofiber membrane was fabricated by the new biomimetic electrospinning technology. The results showed that compared with the pure PLA nanofiber membranes, the average pore size of PLA/GO porous nanofiber membranes decreased, the total number of pores increased, and the fracture strength and elongation at break increased. At the same time, the spun nanofibers were also more uniform. The pore size distribution of nanofiber was more dense after adding DA, and the fracture strength and elongation at break of nanofiber increased, while the nanofiber was also more even. After adding DA, the fracture strength was greatly increased and the elongation at break was similar to that of pure PLA nanofiber. The nanofiber membrane was obtained after oxidative polymerization of DA into poly(dopamine) (PDA), a layer of nanofiber membrane was attached to the surface of nanofiber. The performance of PLA/GO/PDA nanofiber membranes prepared based on PLA/GO/DA nanofiber membranes was superior to that of PLA/GO/PDA nanofiber membranes prepared based on PLA/GO nanofiber membranes, and its adsorption rate after 24 h was as high as 98.81%.

Improving the In Vitro Removal of Indoxyl Sulfate and p-Cresyl Sulfate by Coating Diatomaceous Earth (DE) and Poly-vinyl-pyrrolidone-co-styrene (PVP-co-S) with Polydopamine.

Polydopamine (PDA) is a synthetic eumelanin polymer mimicking the biopolymer secreted by mussels to attach to surfaces with a high binding strength. It exhibits unique adhesive properties and has recently attracted considerable interest as a multifunctional thin film coating. In this study, we demonstrate that a PDA coating on silica- and polymer-based materials improves the entrapment and retention of uremic toxins produced in specific diseases. The low-cost natural nanotextured fossil diatomaceous earth (DE), an abundant source of mesoporous silica, and polyvinylpyrrolidone-co-Styrene (PVP-co-S), a commercial absorbent comprising polymeric particles, were easily coated with a PDA layer by oxidative polymerization of dopamine at mild basic aqueous conditions. An in-depth chemical-physical investigation of both the resulting PDA-coated materials was performed by SEM, AFM, UV-visible, Raman spectroscopy and spectroscopic ellipsometry. Finally, the obtained hybrid systems were successfully tested for the removal of two uremic toxins (indoxyl sulfate and p-cresyl sulfate) directly from patients' sera.

Mussel Inspired Polydopamine as Silica Fibers Coating for Solid-Phase Microextraction

Commercial solid-phase microextraction fibers are available in a limited number of expensive coatings, which often contain environmentally harmful substances. Consequently, several different approaches have been used in the attempt to develop new sorbents that should possess intrinsic characteristics such as duration, selectivity, stability, and eco-friendliness. Herein we reported a straightforward, green, and easy coating method of silica fibers for solid-phase microextraction with polydopamine (PDA), an adhesive, biocompatible organic polymer that is easily produced by oxidative polymerization of dopamine in mild basic aqueous conditions. After FT-ATR and SEM characterization, the PDA fibers were tested via chromatographic analyses performed on UHPLC system using biphenyl and benzo(a)pyrene as model compounds, and their performances were compared with those of some commercial fibers. The new PDA fiber was finally used for the determination of selected PAHs in soot samples and the results compared with those obtained using the commercial PA fiber. Good reproducibility, extraction stability, and linearity were obtained using the PDA coating, which proved to be a very promising new material for SPME.

Hierarchically Porous Mesostructured Polydopamine Nanospheres and Derived Carbon for Supercapacitors.

Polydopamine (PDA), with similar chemical and physical properties to eumelanin, is a typical artificial melanin material. With various functional groups, good biocompatibility, and photothermal conversion ability, PDA attracts great interest and is extensively studied. Endowing PDA with a porous structure would increase its specific surface area, therefore would significantly improve its performance in different application fields. However, creating abundant pores within the PDA matrix is a great challenge. Herein, a self-assembly/etching method is proposed to prepare hierarchically porous mesostructured PDA nanospheres. The oxidative polymerization of dopamine and hydrolysis of tetraethyl orthosilicate were coupled to co-assemble with a polyelectrolyte-surfactant complex template to form a mesostructured PDA/silicate nanocomposite. After removing templates and etching of silica, hierarchically porous PDA nanospheres were obtained with specific surface area and pore volume as high as 302 m2 g-1 and 0.67 cm3 g-1, respectively. Moreover, via subsequent carbonization and silica-etching, ordered mesoporous N-doped carbon microspheres (OMCMs) with ∼2 nm ordered mesopores and ∼20 nm secondary nanopores could be obtained. When used as electrodes of supercapacitors, the OMCMs exhibited a specific capacity of 341 F g-1 at 1 A g-1 with excellent rate capability, and the OMCM-based symmetric supercapacitor delivered a high energy density of 14.1 W h kg-1 at a power density of 250 W kg-1 and minor capacitance fading (only 2.6%) after 10,000 cycles at 2 A g-1.

A copper(II) displacement approach for fluorescent turn-on sensing of glutathione using salicylaldehyde modified polydopamine nanoparticles

The salicylaldehyde modified green-fluorescent polydopamine nanoparticles (PDASA NPs) was synthesized, characterized and applied for the sensing of glutathione (GSH). The oxidative polymerization of dopamine in the presence of salicylaldehyde at pH = 8.5 (10 mM PBS solution) formed the spherical-shaped PDASA NPs with an average diameter of ∼ 150 nm. The addition of Cu(II) to the solution of PDASA NPs in HEPES buffer (10 mM, pH = 7.4) quenched the fluorescence at 490 nm (λex = 390 nm). Experimental evidence supported the fluorescence quenching was static in nature with the estimated Stern-Volmer constant (KSV) of 4.00 × 103 M−1. The fluorescence was restored upon addition of GSH to the solution containing PDASA NPs and Cu(II), among the other examined amino acids (alanine, aspartic acid, glutamic acid, arginine, glycine, cysteine, histidine, serine, leucine, proline, threonine, tryptophan, lysine and methionine). The nanoprobe Cu(II)-PDASA NPs showed a good linearity between 2.20 × 10−5 M and 2.49 × 10−6 M for GSH with an estimated limit of detection of 2.84 × 10−7 M. The Cu(II)-PDASA NPs was applied for the quantification of GSH in urine and saliva samples.

Physicochemical investigation of the enhanced removal of methylene blue from aqueous solution using polydopamine/silver nanoparticles

Polydopamine/Ag (PDA/Ag) nanoparticles were synthesized for methylene blue (MB) removal from aqueous solution as a model dye. These particles were prepared in a modified literature procedure in which polydopamine (PDA) nanoparticles were first prepared via the oxidative polymerization of dopamine (DA) under alkaline conditions in the presence of oxygen. Subsequently, nanoparticulate PDA/Ag was accessed from direct reduction of silver precursor [Ag(NH3)2]+ ions by catechol amino groups in the PDA structure to form Ag nanoparticles (AgNPs) fixed on the PDA surface. Confirmation of the formation of the PDA and PDA/Ag nanoparticles, plus characterization of their surface morphologies was achieved. In the MB adsorption studies, the various factors affecting the dye adsorption and thermodynamic parameters were investigated in detail. This adsorption process can be described well by the Langmuir model. In order to gain a deeper molecular insight into this process, we investigated some possible local model structures of PDA/Ag nanoparticles and MB interaction with these structures using density functional theory (DFT) calculations. The results indicated that the adsorption energies (E ads) of MB on the PDA/Ag nanoparticles were higher than the E ads of MB on PDA nanoparticles, which was consistent with the experimental results. Our results provide a significant new finding for the role of Ag nanoparticles in the MB adsorption process on PDA/Ag nanoparticles. Readily accessible nanoparticulate PDA/Ag was shown to be a highly effective adsorbent for MB from aqueous solution and thus has significant potential for applications in wastewater dye removal.

Multi-Crosslinked Hydrogels with Instant Self-Healing and Tissue Adhesive Properties for Biomedical Applications.

Due to the defects like long gelling time, inferior mechanical properties and weak adhesion, in situ forming hydrogels are still restricted in biomedical applications like viscera rupture and targeted therapy. To address these problems, a new kind of multi-crosslinked hydrogel (G-OKG-DA) consisting of gelatin, oxidized konjac glucomannan (OKG), and dopamine (DA) is proposed in this study. The resulting hybrid hydrogel is endowed with a short gelling time (≈3min) and injectable capacity. According to the mechanical and adhesive tests, G-OKG-DA hydrogel shows a robust tensile strength of 23.94kPa, as well as a higher adhesive strength (≈150kPa) than commercial fibrin glue. In addition, an instant self-healing behavior of G-OKG-DA hydrogel can be found, which is attributed to multi-cross-linking reactions including Schiff-based dynamic covalent bonds between OKG and gelatin, oxidative polymerization of DA, and catechol-mediated chemistry like Michael addition and DA-quinone coupling. Importantly, the multi-crosslinked hydrogel will not compromise its hemocompatibility and cytocompatibility in vitro, suggesting potential applications in biomedical fields as tissue adhesive and implants.

Heterogeneous photosensitizers: Super-efficient dual functional polydopamine nanohybrid for epoxy photopolymerization

The photosensitivity of nanoparticulate polydopamine (PDA) and polydopamine coated multiwalled carbon nanotubes (PDA/MWCNT) and their effect on the photopolymerization of epoxy monomers were systematically investigated. PDA/MWCNT nanohybrid at only 0.625 wt% has been shown to photo-catalyse the polymerization speed and conversion when compared with the commercial free radical photoinitiator, BAPO or non-free radical enhanced cationic photoinitiating resin systems. More importantly, it substantially increased the conversion by more than 140% over the unfilled free radical promoted cationic photoinitiating resin system. Covalent coated PDA/MWCNT nanohybrids were fabricated by oxidative polymerization of dopamine on the surface of acid treated MWCNTs. The modified MWCNT nanofiller has a dual role as photosensitizer/co-initiator in the FRPCP photoinitiating system and as mechanical reinforcement for the epoxy matrix. The use of PDA nanoparticles also led to the improvement in the polymerization process, albeit a limited one. Further evaluation of the observation suggests that the increase in the polymerization speed could be due to the photoinduced electron transfer effect in the polydopamine domain of the hybrid. The super efficiency effect has been explained through the heterojunction formation at the interface of dissimilar semi-conductive/conductive materials, polydopamine, a bio conjugated molecule with UV sensitivity and MWCNT hybrids, in the curing of epoxy monomers. This type of hybridized sensitizers/co-initiators have the potential to be applied in vat type 3D printing technologies such as SLA and DLP enabling printing with light blocking additives which otherwise pose a challenge in UV–Vis enabled curing and printing.

Fabrication of human serum albumin-imprinted photothermal nanoparticles for enhanced immunotherapy.

Photothermal nanoparticles have been confirmed to induce an antitumor immune response and turn "cold tumor" into "hot tumor". However, their delivery efficacy to tumors is limited by the elimination from the reticalendothel system. Herein, human serum albumin (HSA)-imprinted polymer coated Fe3O4 nanoparticles (Fe3O4@MIPs) are fabricated by oxidative polymerization of dopamine in the presence of HSA on the polydopamine pre-modified Fe3O4 nanoparticle surface, followed by the removal of HSA. The Fe3O4@MIPs exhibit rapid and specific reabsorption toward HSA. The molecularly imprinted sites on the Fe3O4@MIPs endow it with an albumin-rich protein corona in the blood and result in less elimination from the reticalendothel system than non-albumin-imprinted particles (Fe3O4@NIPs). Moreover, the molecularly imprinted polymer, which consists of polydopamine, also improves the photothermal effect of Fe3O4 nanoparticles. In vivo, the albumin camouflage in Fe3O4@MIPs produces a 2.6-fold improvement in tumor accumulation in comparison to Fe3O4@NIPs, and more heat is produced upon 808 nm laser irradiation, which further triggers an efficient immunogenic cell death (ICD) progress. Thus, the combination of Fe3O4@MIPs and PD-L1 antibody can not only inhibit the growth of primary tumors but also eliminates lung metastasis by eliciting immunological effect.

Synthetic Porous Melanin.

Commonly known as a skin pigment, melanin has a vital role in UV radiation protection, primarily acting as a radical scavenger. However, a lesser known natural property of melanin, observed in some melanized organisms, is its capacity to adsorb toxins, including metals and organic molecules. Inspired by this, we set out to generate a synthetic porous melanin that would pave the way to enhancing the natural adsorbent properties of melanin and melanin-like materials. Here, we developed a method for the synthesis of porous polydopamine-based melanin utilizing a mesoporous silica (MS) nanoparticle template and characterized its physical properties. Through the oxidative polymerization of dopamine, followed by the etching of silica, we generated synthetic porous melanin (SPM) with the highest measured surface area of any known polydopamine-based material. The prepared SPM was effective for the uptake of various gases and organophosphate toxins, with the material exhibiting high selectivity for CO2 over CH4 and high potential for ammonia capture. Given the demonstrated advantages provided by synthetic porous melanin and melanin's role as an adsorbent in nature, we anticipate the discovery of porous analogues in biological systems.

Antineoplastic behavior of polydopamine nanoparticles prepared in different water/alcohol media

Polydopamine nanoparticles (PD NPs) have been synthesized in the present work through the oxidative polymerization of dopamine in aqueous media containing five different types of alcohol in a constant solvent volume ratio. We have shown that the type of alcohol, along with the ammonium hydroxide concentration used in the synthesis process, conditions particle size. Additionally, it has been found that the type of alcohol employed influences the well-known capacity of polydopamine nanoparticles to adsorb iron. As a consequence, since a ferroptosis-like mechanism may account for the cytotoxicity of these nanoparticles, the type of alcohol could also have a determining role in their antineoplastic activity. Here, the existence of a correlation between the ability of polydopamine nanoparticles to load Fe3+ and their toxic effect on breast cancer cells has been proven. For instance, nanoparticles synthesized using 2-propanol adsorbed more Fe3+ and had the greatest capacity to reduce breast tumor cell viability. Moreover, none of the nanoparticle synthesized with the different alcohols significantly decreased normal cell survival. Cancer cells present greater iron-dependence than healthy cells and this fact may explain why polydopamine nanoparticles toxicity, in which Fenton chemistry could be implicated, seems tumor-specific.

A New Antibacterial N-Halamine Coating Based on Polydopamine.

To prevent the formation of biofilms on material surfaces, the latter must have antibacterial properties. The aim of this study is to investigate the synthesis and the antibacterial effect of a new N-halamine coating based on polydopamine (PDA). The benefits of this coating are multiple, notably the green process used to prepare it and the wide variety of organic or inorganic materials that can be functionalized. First, the formation of the PDA coating by oxidative polymerization of dopamine in weak alkaline aqueous solution was studied and characterized. Then, these PDA films were exposed to a NaOCl solution in order to form chloramine functions into the coating, i.e., to immobilize oxidative chlorine on and into the coating. The PDA film chlorination was notably followed in situ by a quartz crystal microbalance (QCM). The influence of the NaOCl solution pH and concentration on chlorination kinetics and on PDA film degradation was evidenced. Finally, the antibacterial properties of the modified PDA coatings were highlighted by testing their antiadhesion and bactericidal properties toward the Escherichia coli bacterial strain.

When Ultimate Adhesive Mechanism Meets Ultimate Anti‐Fouling Surfaces—Polydopamine Versus SLIPS: Which One Prevails?

AbstractWhat happens when the extremely adhesive and versatile chemistry of polydopamine (PDA) is in contact with the extremely slippery surfaces known as slippery liquid‐infused porous substrates (SLIPS)? Inspired by the pitcher plant, SLIPS possess excellent repellence against a variety of complex liquids and have been proposed as promising antifouling surfaces because of their successful performance even in marine environments. In the counterpart, inspired by the adhesive proteins enabling the strong adhesion of mussels to multiple substrates, PDA has been extensively studied for its ability to adhere on nearly every type of substrate. The interaction between various SLIPS systems and the highly fouling medium from the oxidative polymerization of dopamine is explored here. A PDA coating is observed on all the SLIPS evaluated, modifying their hydrophobicity in most cases. In‐depth study of silicone‐based SLIPS shows that hydrophobicity of PDA coated SLIPS partially recovers with time due to percolation of the lubricant through the coating. “Strongly” bound PDA species are attributed to the formation of dopamine‐polydimethylsiloxane species on the crosslinked matrix, rendering a coating that withstands repeated washing steps in various solvents including water, hexane, and toluene. The results not only satisfy scientific curiosity but also imply a strategy to modify/bond SLIPS.

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.