Novel poly-dopamine adhesive for a halloysite nanotube-Ru(bpy)(3)2+ electrochemiluminescent sensor

Upon designing carboxyl methylcellulose and chitosan-derived nanostructured sorbents for efficient removal of Cd(II) and Cr(VI) from water

Considering that the hazardous heavy metal ions like Cd(II) and Cr(VI) are widely present in the environment, nowadays employing easy-to-handle adsorption-oriented processes are feasible choices towards efficient remediation of Cd(II) and Cr(VI) from aqueous systems. Herein we developed a novel amino-functionalized bead with cost-effectiveness, high sorption capacity and fast sorption kinetics to remove Cd(II) and Cr(VI) from aqueous solution. The carboxyl methylcellulose and chitosan-derived nanostructured sorbents synthesis were mainly through chitosan and dopamine self-polymerization, doped in sodium carboxymethyl cellulose, and glutaraldehyde cross-linking. The pH value, initial concentration and contact time were investigated. Experimental data were commendably described by Freundlich isotherm and Pseudo-second-order model. The maximum adsorption capacities of Cd(II) and Cr(VI) obtained from the experimental data were 470.0 mg/g and 347.0 mg/g, respectively. The adsorbents were collaboratively characterized by FT-IR, SEM, TGA, XPS, etc., and the adsorbent basically exhibited high complexation ability to Cd(II) and showed strong electrostatic effect with Cr(VI) under acidic conditions. The recycling characteristics suggested that it possesses an outstanding recyclability. The adsorbent may have a potential as high-value biological adsorbent to remove heavy metals and it deserves further research into the practical application.

Enhanced degradation of trichloroethylene in oxidative environment by nZVI/PDA functionalized rGO catalyst

Nano zero-valent iron (nZVI) particles with higher reactivity have been recognized as more efficient catalysts than Fe(II) for the groundwater remediation. The rapid emergence of novel catalyst supports efficiently prevent the rapid aggregation of nZVI and further improve catalytic reactivity. However, the lack of ability to avoid the potential oxidation of bare nZVI-support structure in air environment hinders its wider application in the actual contaminated sites. In this study, nZVI on reduced graphene oxide (rGO) functionalized by polydopamine (PDA) (nZVI-PDA@rGO) was synthesized successfully and applied into sodium persulfate (SPS), potassium monopersulfate (PMS) and H₂O₂ oxidative environments to remove trichloroethylene (TCE). For comparison, nZVI supported on solely rGO was prepared. The XRD test displayed the stronger stability of α-Fe(0) in nZVI-PDA@rGO catalyst against oxidation exposed to air. Compared with nZVI-rGO, a core shell structure of nZVI-PDA@rGO was observed in TEM image obviously. The dosage tests showed nZVI-PDA@rGO had a better catalytic reactivity than nZVI-rGO for TCE removal at lower catalyst and oxidant dosages, i.e. PMS dosage: 0.3 mM, catalyst dosage: 50 mg L^-1, TCE removal: 45.0% (nZVI-rGO) up to 99.6% (nZVI-PDA@rGO). TCE removal mechanisms were revealed through radical scavenger tests, demonstrating sulfate radicals played more important role in nZVI-PDA@rGO catalyzed-oxidant systems.

Recent developments in polydopamine: an emerging soft matter for surface modification and biomedical applications

After more than four billion years of evolution, nature has created a large number of fascinating living organisms, which show numerous peculiar structures and wonderful properties. Nature can provide sources of plentiful inspiration for scientists to create various materials and devices with special functions and uses. Since Messersmith proposed the fabrication of multifunctional coatings through mussel-inspired chemistry, this field has attracted considerable attention for its promising and exiciting applications. Polydopamine (PDA), an emerging soft matter, has been demonstrated to be a crucial component in mussel-inspired chemistry. In this review, the recent developments of PDA for mussel-inspired surface modification are summarized and discussed. The biomedical applications of PDA-based materials are also highlighted. We believe that this review can provide important and timely information regarding mussel-inspired chemistry and will be of great interest for scientists in the chemistry, materials, biology, medicine and interdisciplinary fields.

Simultaneous utilization of a bifunctional ruthenium complex as an efficient catalyst for RAFT controlled photopolymerization and a sensing probe for the facile fabrication of an ECL platform

The ruthenium complex played simultaneous bifunctional roles as an efficient catalyst for RAFT-controlled photopolymerization and a sensing probe for the facile fabrication of an ECL platform.

Mussel-inspired protein-mediated surface functionalization of electrospun nanofibers for pH-responsive drug delivery

pH-responsive drug delivery systems could mediate drug releasing rate by changing the pH values at specific times as per the pathophysiological need of the disease. This paper demonstrates that a mussel-inspired protein polydopamine coating can tune the loading and releasing rate of charged molecules from electrospun poly(ε-caprolactone) (PCL) nanofibers in solutions with different pH values. In vitro release profiles show that the positive charged molecules release significantly faster in acidic than those in neutral and basic environments within the same incubation time. The results of fluorescein diacetate staining and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays show the viability of cancer cells after treatment with doxorubicin-released media at different pH values qualitatively and quantitatively, indicating that the media containing doxorubicin that were released in solutions at low pH values could kill a significantly higher number of cells than those released in solutions at high pH values. Together, the pH-responsive drug delivery systems based on polydopamine-coated PCL nanofibers could have potential application in the oral delivery of anticancer drugs for treating gastric cancer and in vaginal delivery of anti-viral drugs or anti-inflammatory drugs, which could raise their efficacy, deliver them to the specific target and minimize their toxic side effects.

Catechol-based biomimetic functional materials

Catechols are found in nature taking part in a remarkably broad scope of biochemical processes and functions. Though not exclusively, such versatility may be traced back to several properties uniquely found together in the o-dihydroxyaryl chemical function; namely, its ability to establish reversible equilibria at moderate redox potentials and pHs and to irreversibly cross-link through complex oxidation mechanisms; its excellent chelating properties, greatly exemplified by, but by no means exclusive, to the binding of Fe(3+); and the diverse modes of interaction of the vicinal hydroxyl groups with all kinds of surfaces of remarkably different chemical and physical nature. Thanks to this diversity, catechols can be found either as simple molecular systems, forming part of supramolacular structures, coordinated to different metal ions or as macromolecules mostly arising from polymerization mechanisms through covalent bonds. Such versatility has allowed catechols to participate in several natural processes and functions that range from the adhesive properties of marine organisms to the storage of some transition metal ions. As a result of such an astonishing range of functionalities, catechol-based systems have in recent years been subject to intense research, aimed at mimicking these natural systems in order to develop new functional materials and coatings. A comprehensive review of these studies is discussed in this paper.