Polydopamine-assisted synthesis of raspberry-like nanocomposite particles for superhydrophobic and superoleophilic surfaces

Ion imprinted differential modulation system based on enhanced optic-fiber evanescent wave for sensitive and label-free detection of trace nickel ions

An optical system with low cost monitoring, high sensitivity, strong selectivity and much lower nickel ion (Ni2+) content in tap water than the World Health Organization (WHO) standard (1.19 μM) has been prepared by a simple strategy. This proposed ion-imprinted differential modulation system is based on the Bragg grating (FBG) and microfiber interferometer structure, and the interferometer sensing surface is coated with a polydopamine (PDA)/graphene oxide (GO) film to enhance its sensitivity. Combined with the ion imprinting technique, the microfiber interferometer sensor sensitivity can reach 0.32 nm/nM with the detection limit of 0.66 nM in the low concentration range (Ni2+ concentration range is 0 nM-100 nM). The experiment not only studies the principle of microfiber interferometer and FBG and their refractive index and temperature performance, but also shows that the FBG power change has a good fitting relationship with wavelength change. In addition, this system performance by the amount of power difference rather than the amount of wavelength shift, which significantly saves on the high cost weight, and size associated with the use of spectral analyzers in traditional inspection systems. This study provides a novel and easy method to develop new sensors with higher comprehensive performance.

Metal Cluster-Based Electrochemical Biosensing System for Detecting Epithelial-to-Mesenchymal Transition

N-cadherin serves as an important oncobiomarker of epithelial-to-mesenchymal transition (EMT) progression, which identifies invasion and metastasis of malignant tumor cells. Although many efforts have been devoted to quantitative detection of N-cadherin, efforts to analyzing the protein of interest at intact cellular levels are scarce. Herein, a metal cluster-based electrochemical biosensing system is developed to determine the expressing levels of N-cadherin during the EMT process of tumor cells. To be specific, a peptide with a unique sequence and function is designed as a reductant and an anchor to synthesize metal clusters in a precise manner. Consequently, peptide-modified metal clusters possess N-cadherin-targeting, photoluminescence, and electrocatalytic properties. Especially, the redox-active metal clusters function as both an electron-transfer mediator and an electronic conductor for enhanced electrochemical sensing. These favorable features enable them as a rapid, sensitive, and reliable whole-cell biosensor, which integrates the fluorescence and electrochemical signals. This cytosensor can accurately quantify the expression levels of N-cadherin on at least 5000 tumor cells. Further, the current signals of model cancer cells gradually increase with EMT progression, indicating tumor cell-type evolution. Our study represents the advanced bioprobe and analytical methods for accurate quantitation of a biomarker to identify tumor progression.

Synthetic strategies for raspberry-like polymer composite particles

The strategies used for the preparation of raspberry-like polymer composite particles are summarized comprehensively.

An efficient antimicrobial depot for infectious site-targeted chemo-photothermal therapy

Background

Silver and photothermal therapy (PTT) have been widely used for eradicating the drug-resistant bacteria. However, the risks of excess of silver for humans and the low efficiency of PTT still limit their in vivo therapeutic application. Integration of two distinctive bactericides into one entity is a promising platform to improve the efficiency of antimicrobial agents.

Results

In this study, a chemo-photothermal therapeutic platform based on polydopamine (PDA)-coated gold nanorods (GNRs) was developed. The PDA coating acquired high Ag⁺ ions loading efficiency and Cy5-SE fluorescent agent labeled glycol chitosan (GCS) conjugation (Ag⁺-GCS-PDA@GNRs). This platform became positively charged in the low pH environment of the abscess, allowing their accumulation in local infection site as revealed by thermal/florescence imaging. The loaded Ag⁺ ions was released in a pH-sensitive manner, resulting in selective Ag⁺ ions delivery to the abscess environment (pH ~ 6.3). More importantly, the ultralow dose of Ag⁺ ions could effectively damage the bacterial membrane, causing the permeability increase and the heat resistance reduction of the cell membrane, leading to the large improvement on bactericidal efficiency of PTT. On the other hand, the hyperthermia could trigger more Ag⁺ ions release, resulting in further improvement on bactericidal efficiency of chemotherapy. Combinational chemo-hyperthermia therapy of Ag⁺-GCS-PDA@GNRs could thoroughly ablate abscess and accelerate wound healing via a synergistic antibacterial effect.

Conclusions

Our studies demonstrate that Ag⁺-GCS-PDA@GNRs is a robust and practical platform for use in chemo-thermal focal infection therapy with outstanding synergistic bacteria ablating.

Electronic supplementary material

The online version of this article (10.1186/s12951-018-0348-z) contains supplementary material, which is available to authorized users.

Polydopamine Based Colloidal Materials: Synthesis and Applications

Polydopamine is a synthetic analogue of natural melanin (eumelanin) produced from oxidative polymerization of dopamine. Owing to its strong adhesion ability, versatile chemical reactivity, biocompatibility and biodegradation, polydopamine is commonly applied as a versatile linker to synthesize colloidal materials with diverse structures, unique physicochemical properties and tunable functions, which allow for a broad scope of applications including biomedicine, sensing, catalysis, environment and energy. In this personal account, we discuss first about the different synthetic approaches of polydopamine, as well as its polymerization mechanism, and then with a comprehensive overview of recent progress in the synthesis and applications of polydopamine-based colloidal materials. Finally, we summarize this personal account with future perspectives.

Ellipsoidal Colloids with a Controlled Surface Roughness via Bioinspired Surface Engineering: Building Blocks for Liquid Marbles and Superhydrophobic Surfaces

Understanding the important role of the surface roughness of nano/colloidal particles and harnessing them for practical applications need novel strategies to control the particles' surface topology. Although there are many examples of spherical particles with a specific surface roughness, nonspherical ones with similar surface features are rare. The current work reports a one-step, straightforward, and bioinspired surface engineering strategy to prepare ellipsoidal particles with a controlled surface roughness. By manipulating the unique chemistry inherent to the oxidation-induced self-polymerization of dopamine into polydopamine (PDA), PDA coating of polymeric ellipsoids leads to a library of hybrid ellipsoidal particles (PS@PDA) with a surface that decorates with nanoscale PDA protrusions of various densities and sizes. Together with the advantages originated from the anisotropy of ellipsoids and rich chemistry of PDA, such a surface feature endows these particles with some unique properties. Evaporative drying of fluorinated PS@PDA particles produces a homogeneous coating with superhydrophobicity that arises from the two-scale hierarchal structure of microscale interparticle packing and nanoscale roughness of the constituent ellipsoids. Instead of water repelling that occurs for most of the lotus leaf-like superhydrophobic surfaces, such coating exhibits strong water adhesion that is observed with certain species of rose pedals. In addition, the as-prepared hybrid ellipsoids are very efficient in preparing liquid marble-isolated droplets covered with solid particles. Such liquid marbles can be placed onto many surfaces and might be useful for the controllable transport and manipulation of small volumes of liquids.

Facile fabrication of raspberry-like composite microspheres for the construction of superhydrophobic films and applications in highly efficient oil–water separation

Inspired by the “lotus effect”, we proposed a facile synthetic route toward raspberry-like PS@SiO₂ microspheres, which further lead to superhydrophobic surfaces.

Hydrophilic, hollow Fe3O4@PDA spheres with a storage cavity for efficient removal of polycyclic structured tetracycline

Biomimetic hydrophilic hollow polydopamine (PDA)-based composites of Fe₃O₄@PDA for the efficient removal of polycyclic structured tetracycline were facilely synthesized.

Electro-Optical Properties of Low-Temperature Growth Indium-tin-oxide Nanowires Using Polystyrene Spheres as Catalyst

Polystyrene sphere was chosen as a catalyst to fabricate indium-tin-oxide (ITO) nanowires (NWs) with a low-temperature (280-300 °C) electron-beam deposition process, bearing high purity. The ITO NWs with diameter of 20-50 nm and length of ~2 um were obtained. X-ray diffraction and high-resolution transmission electron microscope show high crystal quality. The transmittance is above 90 % at a wavelength 400 nm or more, superior to the ITO bulk film. Owing to the unique morphology gradient of the ITO NWs, the effective refractive index of ITO NWs film is naturally graded from the bottom to the top. The ITO NWs have been used on LED devices (λ = 450 nm), which improved the light output power by 31 % at the current of 150 mA comparing to the one without NWs and did not deteriorate the electrical properties. Such ITO NWs open opportunity in LED devices to further improve light extraction efficiency.

Polydopamine-functionalized polymer particles as templates for mineralization of hydroxyapatite: biomimetic and in vitro bioactivity

Polydopamine-assisted biomimetic mineralization was presented to fabricate hydroxyapatite-based, organic–inorganic hybrid materials with excellent biocompatibility.

Multifunctional hollow polydopamine-based composites (Fe3O4/PDA@Ag) for efficient degradation of organic dyes

As a newly appeared biomimetic platform and universal surface modification agent, polydopamine (PDA) has been paid great attention recently.

A facile strategy to fabricate covalently linked raspberry-like nanocomposites with pH and thermo tunable structures

A simple and controllable route to prepare covalently bonded raspberry-like composite particles with pH and thermal dual-responsiveness.

Preparation of silver decorated silica nanocomposite rods for catalytic and surface-enhanced Raman scattering applications

A straightforward approach is presented to prepare SiO₂@Ag nanocomposite rods with excellent catalytic activities and surface-enhanced Raman scattering properties.

Compatibilizing action and localization of clay in a polypropylene/natural rubber (PP/NR) blend

The compatibilizing action of clay in polypropylene (PP)/natural rubber (NR) blends and its effect on mechanical properties have been investigated.

Fabrication of silver-decorated sulfonated polystyrene microspheres for surface-enhanced Raman scattering and antibacterial applications

A facile approach was presented to prepare SPS@Ag composite microspheres with surface-enhanced Raman scattering properties and enhanced antibacterial activities.