Showing papers by "Lifeng Yan published in 2015"

Galactose targeted pH-responsive copolymer conjugated with near infrared fluorescence probe for imaging of intelligent drug delivery.

Abstract: Theranostic polymeric nanomaterials are of special important in cancer treatment. Here, novel galactose targeted pH-responsive amphiphilic multiblock copolymer conjugated with both drug and near-infrared fluorescence (NIR) probe has been designed and prepared by a four-steps process: (1) ring-opening polymerization (ROP) of N-carboxy anhydride (NCA) monomers using propargylamine as initiator; (2) reversible addition–fragmentation chain transfer (RAFT) polymerization of oligo(ethylene glycol) methacrylate (OEGMA) and gal monomer by an azido modified RAFT agent; (3) combing the obtained two polymeric segments by click reaction; (4) NIR copolymer prodrug was synthesized by chemical linkage of both cyanine dye and anticancer drug doxorubicin to the block copolymer via amide bond and hydrazone, respectively. The obtained NIRF copolymers were characterized by nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), and its was measured by means of micelles dynamic light scattering (DLS), field emi...

Free-standing dried foam films of graphene oxide for humidity sensing

Abstract: Transparent free-standing films of graphene oxide (GO) have been prepared by a dried foam method using different oxygen-containing GO sheets as feedstocks. Then a humidity sensor was fabricated using the films as transparent and flexible sensing materials. The impedances of the films were measured at different relative humidity, and the results revealed that the relationship between impedance and relative humidity depends on both the oxygen content and the thickness of the GO films, and a linear relationship corresponds to an ultrathin film (in thickness of about 100 nm) while a non-linear relationship for thick films. In addition, the thin film can also show a dynamic switch behavior for humidity sensing. The transparent free-standing GO film has potential application working as an optical window combing the humidity sensing property.

Reduced graphene oxide hydrogel film with a continuous ion transport network for supercapacitors

Abstract: Stacking of Graphene usually results in a close packing of graphene nanosheeets corresponding to a low specific surface area and pore volume. A new simple method to prepare reduce graphene oxide (rGO) film has been developed using an in situ electrochemical reduction of the as-formed GO hydrogel film in an aqueous solution electrolyte. The as-obtained rGO hydrogel film has a highly specific surface area and was directly used as the electrodes for a supercapacitor, in which the ion channels remained with excellent capacitance, even at a high current density. The as-obtained rGO hydrogel film has also been used to prepare a flexible belt-like supercapacitor, which may light up a LED lamp for more than two minutes. Electrochemical in situ reduction provides a simple method to prepare novel graphene based supercapacitors for a wide variety of applications in the near future.

Metal-free transparent luminescent cellulose films

Abstract: As functional materials, luminescent films have a wide range of applications in terms of displays, light-emitting devices, safety signs and sensors. Cellulose is the most abundant renewable resource in the world and plays an important role in the field of membrane synthesis. Here, cellulose was dissolved in 7 % NaOH/12 % urea aqueous solution, and the regenerated cellulose films were prepared in acid media. N and S doping carbon quantum dots (C-QDs) were synthesized as the high-efficiency luminescent materials, and the nanocomposite films of cellulose/C-QD were prepared by fixing the C-QDs onto the surface of regenerated cellulose fibers. Fourier transform infrared spectrometry, X-ray diffraction, atomic force microscopy and scanning electron microscopy measurements were used to measure the structure and properties of the film. The as-prepared film was transparent and luminescent in the visible region with high mechanical strength. In addition, no metal was involved in the luminescent film, which makes it safe and lightweight, and the film has potential applications in many fields. Metal-free cellulose/carbon QDs composite film was prepared, and the film was highly transparent and luminescent.