Polydopamine Shell Research Articles

Specific removal of protein using protein imprinted polydopamine shells on modified amino-functionalized magnetic nanoparticles

A simple approach for the specific removal of protein using polydopamine imprinted shells on modified amino-functionalized magnetic nanoparticles was developed.

Mussel-Inspired Polydopamine: A Biocompatible and Ultrastable Coating for Nanoparticles in Vivo

Bioinspired polydopamine (PDA) has served as a universal coating to nanoparticles (NPs) for various biomedical applications. However, one remaining critical question is whether the PDA shell on NPs is stable in vivo. In this study, we modified gold nanoparticles (GNPs) with finely controlled PDA nanolayers to form uniform core/shell nanostructures (GNP@PDA). In vitro study showed that the PDA-coated GNPs had low cytotoxicity and could smoothly translocate to cancer cells. Transmission electron microscopy (TEM) analysis demonstrated that the PDA nanoshells were intact within cells after 24 h incubation. Notably, we found the GNP@PDA could partially escape from the endosomes/lysosomes to cytosol and locate close to the nucleus. Furthermore, we observed that the PDA-coated NPs have very different uptake behavior in two important organs of the liver and spleen: GNP@PDA in the liver were mainly uptaken by the Kupffer cells, while the GNP@PDA in the spleen were uptaken by a variety of cells. Importantly, we proved the PDA nanoshells were stable within cells of the liver and spleen for at least six weeks, and GNP@PDA did not show notable histological toxicity to main organs of mice in a long time. These results provided the direct evidence to support that the PDA surface modification can serve as an effective strategy to form ultrastable coatings on NPs in vivo, which can improve the intracellular delivery capacity and biocompatibility of NPs for biomedical application.

Core–Shell Fe3O4Polydopamine Nanoparticles Serve Multipurpose as Drug Carrier, Catalyst Support and Carbon Adsorbent

We present the synthesis and multifunctional utilization of core-shell Fe3O4 polydopamine nanoparticles (Fe3O4@PDA NPs) to serve as the enabling platform for a range of applications including responsive drug delivery, recyclable catalyst support, and adsorbent. Magnetite Fe3O4 NPs formed in a one-pot process by the hydrothermal approach were coated with a polydopamine shell layer of ~20 nm in thickness. The as prepared Fe3O4@PDA NPs were used for the controlled drug release in a pH-sensitive manner via reversible bonding between catechol and boronic acid groups of PDA and the anticancer drug bortezomib (BTZ), respectively. The facile deposition of Au NPs atop Fe3O4@PDA NPs was achieved by utilizing PDA as both the reducing agent and the coupling agent. The nanocatalysts exhibited high catalytic performance for the reduction of o-nitrophenol. Furthermore, the recovery and reuse of the catalyst was demonstrated 10 times without any detectible loss in activity. Finally, the PDA layers were converted into carbon to obtain Fe3O4@C and used as an adsorbent for the removal of Rhodamine B from an aqueous solution. The synergistic combination of unique features of PDA and magnetic nanoparticles establishes these core-shell NPs as a versatile platform for multiple applications.

Interface Chemistry Guided Long-Cycle-Life Li–S Battery

To date, most of the research on electrodes for energy storage has been focused on the active material itself. It is clear that investigating isolated active materials is no longer sufficient to solve all kinds of technological challenges for the development of modern battery infrastructure. From the interface chemistry point of view, a system-level strategy of designing polydopamine coated reduced graphene oxide/sulfur composite cathodes aimed at enhancing cyclic performance was reported in this work. As a soft buffer layer, the polydopamine shell was used to accommodate the volume expansion of S and avoid the leakage of polysulfide during cycling. A cross-link reaction between polydopamine buffer and poly(acrylic acid) binder was further designed to improve the strength of the entire electrode. As a result, the electrode demonstrated excellent cyclic performance with a discharge capacity of 728 mAh/g after 500 cycles at the current density of 0.5 A/g (a very small capacity loss of 0.41 mAh/g per cycle). Most importantly, 530 mAh/g was obtained even at a higher current density of 1 A/g after 800 cycles. Our results indicate the importance of chemically designing interfaces in the whole electrode system on achieving improved performance of electrodes of rechargeable lithium ion batteries.

Silicon nanoparticles encapsulated in hollow graphitized carbon nanofibers for lithium ion battery anodes

Silicon (Si) is a promising material for lithium ion battery (LIB) anodes due to its high specific capacity. To overcome its shortcomings such as insulation property and large volume change during the charge-discharge process, a novel hybrid system, Si nanoparticles encapsulated in hollow graphitized carbon nanofibers, is studied. First, electrospun polyacrylonitrile (PAN)-Si hybrid nanofibers were obtained using water as the collector. The loose nanofiber lumps suspended in water have large inter-fiber distance, allowing in situ coating of a thin layer of polydopamine (PDA), the source for graphitized carbon, uniformly throughout the system. The designed morphology and structure were then realized by etching and calcination, and the morphology and structure were subsequently verified by various analytical techniques. Electrochemical measurements show that the resulting hollow hybrid nanofibers (C-PDA-Si NFs) exhibit much better cycling stability and rate capacity than conventional C/Si nanofibers derived by electrospinning of PAN-Si followed by calcination. For instance, the capacity of C-PDA-Si NFs is as high as 72.6% of the theoretical capacity after 50 cycles, and a high capacity of 500 mA h g(-1) can be delivered at a current density of 5 A g(-1). The significantly improved electrochemical properties of C-PDA-Si NFs are due to the excellent electrical conductivity of the carbonized PDA (C-PDA) shell that compensates for the insulation property of Si, the high electrochemical activity of C-PDA, which has a layered structure and is N-doped, the hollow nature of the nanofibers and small size of Si nanoparticles that ensure smooth insertion-extraction of lithium ions and more complete alloying with them, as well as the buffering effect of the remaining PAN-derived carbon around the Si nanoparticles, which stabilizes the structure.

A self-assembled polydopamine film on the surface of magnetic nanoparticles for specific capture of protein

In this study, we report a facile method for the preparation of core-shell magnetic molecularly imprinted polymers (MIPs) for protein recognition. Uniform carboxyl group functionalized Fe(3)O(4) nanoparticles (NPs) were synthesized using a solvothermal method. Magnetic MIPs were synthesized by self-polymerization of dopamine in the presence of template protein on the surface of the Fe(3)O(4) NPs. A thin layer of polydopamine can be coated on Fe(3)O(4) NPs via dopamine self-polymerization and the imprinted polydopamine shells can be controlled by the mass ratio of Fe(3)O(4) NPs and dopamine. More importantly, there is a critical value of polydopamine shell thickness for the maximum rebinding capacity. The as-prepared lysozyme-imprinted Fe(3)O(4)@polydopamine NPs show high binding capacity and acceptable specific recognition behavior towards template proteins. This method provides the possibility for the separation and enrichment of abundant proteins in proteomic analysis.

One-step synthesis of monodisperse polydopamine-coated silver core–shell nanostructures for enhanced photocatalysis

Nanosized silver (Ag) and polydopamine (PDA) composite was prepared via one-step polymerization of dopamine, using Ag+ ion as an oxidant. The oxidization of dopamine and the reduction of Ag+ ion occurred simultaneously in one-step, which resulted in a well-defined core–shell structure of PDA coating around the Ag nanoparticles (AgNPs). Its morphology, structure, and composition were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray power diffraction (XRD), UV-vis, Fourier transform infrared (FT-IR) spectroscopy, cyclic voltammograms (CVs) and electrochemical impedance spectroscopy (EIS), respectively. The composite showed good performance toward the photo-catalytic degradation of neutral red under UV irradiation. The possible mechanism regarding the plasmon-induced photocatalysis was discussed in some detail, where the main active species of O2˙− on the surface of the AgNPs were involved in this photoreaction system. The PDA shells greatly improve the photocatalysis due to the existence of the π–π* electron transition under UV light.

Mussel-Inspired Encapsulation and Functionalization of Individual Yeast Cells

The individual encapsulation of living cells has a great impact on the area of cell-based sensors and devices as well as fundamental studies in cell biology. In this work, living yeast cells were individually encapsulated with functionalizable, artificial polydopamine shells, inspired by an adhesive protein in mussels. Yeast cells maintained their viability within polydopamine, and the cell cycle was controlled by the thickness of the shells. In addition, the artificial shells aided the cell in offering much stronger resistance against foreign aggression, such as lyticase. After formation of the polydopamine shells, the shells were functionalized with streptavidin by utilizing the chemical reactivity of polydopamine, and the functionalized cells were biospecifically immobilized onto the defined surfaces. Our work suggests a biomimetic approach to the encapsulation and functionalization of individual living cells with covalently bonded, artificial shells.

Preparation of IDA-Cu functionalized core–satellite Fe3O4/polydopamine/Au magnetic nanocomposites and their application for depletion of abundant protein in bovine blood

In this study, we report a method to synthesize core–satellite structured Fe3O4/polydopamine/Au composite nanoparticles (NPs). Firstly, the Fe3O4/polydopamine composite NPs with a well-defined core–shell structure are obtained using dopamine self-polymerization to form thin, surface-adherent polydopamine films onto the surface of a Fe3O4 “core”. The polydopamine shell could be adjusted by controlling the experimental parameters such as reaction time and the reactant concentrations. Then, numerous “satellites” of gold nanoparticles were assembled on the surface of Fe3O4/polydopamine by reducing Au3+ between the Fe3O4/polydopamine solid and HAuCl4 solution. Next, 11-mercaptoundecanoic acid (11-MUA) forms a self-assembled monolayer of MUA on the surface of the Au NPs and polydopamine layer. Finally, IDA-Cu functionalized Fe3O4/polydopamine/Au composite NPs are obtained by the carboxyl groups of MUA reacting with iminodiacetic acid (IDA), charged with Cu2+. The IDA-Cu groups, acting as an “anchor”, are attached on the gold and the polydopamine surface is designed for capturing target molecules. The morphology, structure and composition of the nanocomposites are characterized by transmission electron microscopy (TEM), X-ray powder diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and X-ray photoelectron spectrometry (XPS). The resulting Fe3O4/polydopamine/Au composite NPs show not only a strong magnetic response to an externally applied magnetic field, but are also highly specific to protein bovine hemoglobin (BHb), and removal of abundant protein BHb in the bovine blood as well. This opens a novel route for future application in removing abundant protein in proteomic analysis.