Pengcheng Du

Encapsulation of drug microparticles with self-assembled Fe3O4/alginate hybrid multilayers for targeted controlled release†

The magnetic-targeted drug-delivery system was developed with the Fe(3)O(4) nanoparticles as the self-assembling material to form the hybrid multilayer shells. Layer-by-Layer stepwise self-assembly of the natural polyelectrolytes sodium alginate and the Fe(3)O(4) nanoparticles was used to create the magnetic hybrid multilayers around drug microparticles (~400 nm in diameter) for the purpose of targeted controlled release. The obtained drug microparticles encapsulated with hybrid multilayers were characterized with dynamic light scattering, transmission electron microscope, and vibrating sample magnetometer. UV-vis spectroscopy was employed to monitor the drug releasing behaviors in pH 1.8 and 7.4 buffer solutions. It was found that the release of drug molecules from the pH-sensitive magnetic-targeted drug-delivery system was mainly dependent on the following factors: the permeability of the hybrid multilayer shells and the solubility of the drug molecules in the bulk solutions. The results revealed that it could achieve the quick and continuous controlled release via the magnetically-guide to the target tissue of organism.

Biocompatible and Biodegradable Polymeric Nanocapsules from Poly(α,β-malic acid)-Grafted Nano-silica Templates

A green strategy for the preparation of biocompatible and biodegradable polymeric nanocapsules containing lots of functional carboxyl groups is developed by the surface polycondensation of α,β-malic acid from silica nanoparticles as the sacrificial templates. After the poly(α,β-malic acid) grafted silica nanoparticles are cross-linked with glycerol, the nano-silica templates are etched with hydrofluoric acid to produce the biocompatible and biodegradable polymeric nanocapsules. The hollow structure of the polymeric nanocapsules with an inner diameter about 20–100 nm is validated by transmission electron microscopy.

Skeleton/skin structured (RGO/CNTs)@PANI composite fiber electrodes with excellent mechanical and electrochemical performance for all-solid-state symmetric supercapacitors

Polyaniline coated reduced graphene oxide/carbon nanotube composite fibers ((RGO/CNTs)@PANI, RCP) with skeleton/skin structure are designed as fiber-shaped electrodes for high performance all-solid-state symmetric supercapacitor. The one-dimensional reduced graphene oxide/carbon nanotube composite fibers (RGO/CNTs, RC) are prepared via a simple in-situ reduction of graphene oxide in presence of carbon nanotubes in quartz glass pipes, which exhibit excellent mechanical performance of >193.4 MPa of tensile strength. Then polyaniline is coated onto the RC fibers by electrodepositing technique. The electrochemical properties of the RCP fiber-shaped electrodes are optimized by adjusting the feeding ratio of carbon nanotubes. The optimized one exhibits good electrochemical characteristic such as highest volumetric specific capacitance of 193.1 F cm-3 at 1 A cm-3, as well as excellent cyclic retention of 92.60% after 2000 cyclic voltammetry cycles. Furthermore, the all-solid-state symmetric supercapacitor, fabricated by using the final composite fiber as both positive and negative electrodes pre-coated with the poly(vinyl alcohol)/H2SO4 gel polyelectrolyte, possesses volumetric capacitance of 36.7 F cm-3 at 0.2 A cm-3 and could light up a red light-emitting diode easily. The excellent mechanical and electrochemical performances make the designed supercapacitor as promising high performance wearable energy storage device.

Preparation of Photo-Sensitive Degradable Polymeric Nanocapsules from Dendrimer Grafted Nano-Silica Templates

The poly-hydroxylated photo-sensitive degradable polymeric nanocapsules were prepared by the condensation of the A2-type monomer 4, 4′-Azobenzene dibenzoyl chloride (ADC) and the B3-type monomer triethanolamine (TEA) from the sacrificial nano-silica templates by a divergent approach. After the dendrimer molecules grafted on the silica nanoparticles were cross-linked with ADC, which is both the monomer and the cross-linker in this approach developed subsequently, the silica templates were removed by being etched with hydrofluoric (HF) to produce the photo-sensitive degradable polymeric nanocapsules. The hollow structure of the polymeric nanocapsules with the inner diameter about 20–100 nm is characterized by transmission electron microscopy (TEM). The photo-responsive behavior of the nanocapsules is confirmed by UV-Vis spectroscopy.

Comparative study on polyvinyl chloride film as flexible substrate for preparing free-standing polyaniline-based composite electrodes for supercapacitors

The free-standing polyaniline (PANI)-based composite film electrodes were prepared with polyvinyl chloride (PVC) and the aniline modified PVC (PVC-An) films as flexible substrates for supercapacitors, via facile in-situ chemical oxidative polymerization of aniline, with conventional chemical oxidative polymerization or rapid-mixing chemical oxidative polymerization technique. Owing to the grafting of PANI from the PVC-An film as substrate and the suppression of the secondary growth of the primary PANI particles in the rapid-mixing chemical oxidative polymerization, the PVC-g-PANI-2 composite film with loose surface possessed better comprehensive performance, accompanying the high specific capacitance (645.3F/g at a current density of 1A/g), good rate capacitance (retaining 63.2% of original value at a current density of 10A/g and 52.0% at a scan rate of 100mV/s), good cycle stability (retaining 83.1% after 1000 cycles) and the improved internal resistance. Besides its excellent flexibility, it could retain 61.2% of its original specific capacitance under the stress of 8.66MPa for 1h, demonstrating a good tensile-resistance.

Fabrication of hierarchical porous nickel based metal-organic framework (Ni-MOF) constructed with nanosheets as novel pseudo-capacitive material for asymmetric supercapacitor

Hierarchical porous nickel based metal-organic framework (Ni-MOF) constructed with nanosheets is fabricated by a facile hydrothermal process with the existence of trimesic acid and nickel ions. Various structures of Ni-MOFs can be obtained through adjusting the molar ratio of trimesic acid and nickel ion, the obtained hierarchical porous Ni-MOF exhibits optimal porous structure, which also possesses largest specific surface area. The hierarchical porous structure constructed with nanosheets can supply more active sites for electrochemical reactions to realize the excellent electrochemical properties, thus the hierarchical porous Ni-MOF reveals an outstanding specific capacitance of 1057 F/g at current density of 1 A/g, and delivers high specific capacitance of 649 F/g at current density of 30 A/g, indicating that it exhibits good rate capability of 63.4% even up to 30 A/g. The hierarchical porous Ni-MOF keeps 70% of its original value up to 2 500 charge-discharge cycles at the current density of 10 A/g. Furthermore, asymmetric supercapacitors (ASCs) were assembled based on hierarchical porous Ni-MOF and activated carbon (AC), the ASCs reveal specific capacitance of 87 F/g at current density of 0.5 A/g, and exhibit high energy density of 21.05 Wh/kg and power density of 6.03 kW/kg. Additionally, the tandem ASCs can light up a red LED. The hierarchical porous Ni-MOF exhibits promising applications in high performance supercapacitors.