Synthesis of Polyethylene Terephthalate (PET) with High Crystallization and Mechanical Properties via Functionalized Graphene Oxide as Nucleation Agent.

In this work, a novel functionalized graphene oxide nucleating agent (GITP) was successfully synthesized using a silane coupling agent (IPTES), and polymer block (ITP) to efficiently improve the crystallization and mechanical performance of PET. To comprehensively investigate the effect of functionalized GO on PET properties, PET/GITP nanocomposites were prepared by introducing GITP into the PET matrix using the melt blending method. The results indicate that PET/GITP exhibits better thermal stability and crystallization properties compared with pure PET, increasing the melting temperature from 244.1 °C to 257.1 °C as well as reducing its crystallization half-time from 595 s to 201 s. Moreover, the crystallization temperature of PET/GITP nanocomposites was increased from 185.1 °C to 207.5 °C and the tensile strength was increased from 50.69 MPa to 66.8 MPa. This study provides an effective strategy for functionalized GO as a nucleating agent with which to improve the crystalline and mechanical properties of PET polyester.

Facile immobilization of glucose oxidase with Cu3(PO4)2·3H2O for glucose biosensing via smartphone.

A smartphone-based colorimetric platform for facile glucose detection was constructed below. First, glucose oxidase-Cu3(PO4)2·3H2O hybrid microflowers (GOx-HMFs) were facilely synthesized via biomineralization, which can react with glucose and 3,3',5,5'-tetramethylbenzidine to generate colored product. Next, the color information of product was real-time collected and processed via smartphone to realize accurate glucose detection. The as-constructed colorimetric platform based on GOx-HMFs and smartphone had wide linear range, high sensitivity and good selectivity for glucose detection, moreover, the detection process was convenient and efficient, which provided a new idea for glucose detection.

Facile synthesis of recyclable laccase-mineral hybrid complexes with enhanced activity and stability for biodegradation of Evans Blue dye.

Two morphologies of laccase-mineral hybrid complexes, i.e., laccase-mineral hybrid nanoflowers (La-HNF) and nanopetals (La-HNP), were synthesized via biomineralization using Cu3 (PO4)2·3H2O as the mineral for Evans Blue (EB) dye biodegradation. XRD patterns and FT-IR spectra results revealed the successful immobilization of laccase via in-situ formed Cu3(PO4)2·3H2O crystals. Compared with free laccase, laccase-mineral hybrid complexes showed higher enzymatic activity due to the activation effect induced by copper ions of Cu3(PO4)2·3H2O, further, the improved kinetic parameters of laccase-mineral hybrid complexes could be ascribed to nanoscale-dispersed laccase molecules within hybrid complexes. For EB dye biodegradation, the reason why the biodegradation efficiency (94.9%) of La-HNF was higher than that (86.8%) of La-HNP could be synergistic effect of immobilized laccase within 3D hierarchical structure of La-HNF. In addition, the optimized biodegradation conditions (pH 4.6 and 40 °C) of La-HNF were obtained, moreover, 93.2% and 48.1% of EB dye were biodegraded by La-HNF after stored for 30 days and reused for 10 cycles, respectively, demonstrating La-HNF have good practicability.

Self-Photoluminescence of Unzipped Multi-Walled Carbon Nanotubes.

Unzipping of carbon nanotubes (CNTs) has been widely explored to obtain new nanocarbon structures with promising properties. In this work, we report that unzipping of CNTs according to the well-established modified Hummers method produces unzipped CNTs (uCNTs) that exhibit self-photoluminescence that depends on the diameter of pristine CNTs. The uCNTs were characterized using FTIR spectroscopy, XRD, XPS, and Raman spectroscopy indicating that unzipping is accompanied by the introduction of defects and oxygen-containing functional groups. The morphology of CNTs and uCNTs was determined by TEM showing longitude unzipping of CNTs. Our study shows that increasing the diameter of pristine CNTs results in decreasing the edge etching effect and decreasing the functionality of uCNTs. Based on the UV-Vis spectra, the band gap of uCNTs was calculated using the Kubelka-Munk function. The band gap of uCNTs increased with decreasing diameter of pristine CNTs. The uCNTs exhibited photoluminescence with a good emission in the visible light region. The uCNTs with the largest band gap and the highest oxygen content had the strongest fluorescence intensity. Moreover, different metal ions produced different degrees of fluorescence quenching for uCNT-15, which verified the self-photoluminescence of uCNTs.

A smartphone-assisted portable biosensor using laccase-mineral hybrid microflowers for colorimetric determination of epinephrine.

A novel smartphone-assisted portable biosensor based on laccase-mineral hybrid microflowers (La-HMFs) was applied for real-time, accurate and reliable quantification of epinephrine (EP). La-HMFs with flower-like hierarchical nanostructure was synthesized via biomineralization using Cu3(PO4)2⋅3H2O as the mineral. Characterization results revealed laccase molecules as the framework were immobilized within La-HMFs. Smartphone-assisted colorimetric assays showed wide linear detection range (1-400 µM) and favorable anti-interference ability for EP detection, and the detection limit was 0.6 µM. Further, due to the protective effect of Cu3(PO4)2⋅3H2O, the immobilized laccase exhibited good stability and desirable reusability.

Preparation of QDs@SiO2-PEG-LMPET and its influence on crystallization and luminescence of polyethylene terephthalate.

The composite particles composed of quantum dots coated with silica and grafted with copolymer of polyethylene glycol and low molecular weight polyethylene terephthalate (QDs@SiO2-PEG-LMPET) are synthesized. The internal QDs provide luminescent performance and combine with SiO2to form QDs@SiO2with good dispersion to solve the defect that small-sized SiO2is prone to agglomerate. The block polymer LMPET-PEG grafted on the surface can make the composite particles better compatible with the PET matrix. In summary, QDs@SiO2-PEG-LMPET not only play the same role as SiO2to enhance the crystallization performance of PET matrix, but also provide stable luminescence performance, which is multifunctional additive with broad application prospects.

UV-Vis detection of hydrogen peroxide using horseradish peroxidase/copper phosphate hybrid nanoflowers.

A colorimetric platform based on enzyme-inorganic hybrid nanoflowers was used for ultraviolet-visible detection of hydrogen peroxide (H2O2). The hybrid nanoflowers were prepared via incubation at room temperature using horseradish peroxidase (HRP) and copper phosphate (Cu3(PO4)2) as the organic and inorganic components, respectively. HRP/Cu3(PO4)2 hybrid nanoflowers (HRP-HNFs) showed linear H2O2 detection range from 100 nM to 100 µM, moreover, HRP-HNFs exhibited good selectivity for H2O2 detection due to the specificity of HRP. In addition, HRP-HNFs have good reusability, excellent color stability and long-term storage stability, which indicate HRP-HNFs are promising for catalysis and biomedical applications.

Strongly enhanced efficiency of polymer solar cells through unzipped SWNT hybridization in the hole transport layer.

Single-walled carbon nanotubes (SWNTs) have good conductivity, but their size can't match the heterojunction nanostructure in polymer solar cells (PSCs). To improve the photovoltaic performance of PSCs, herein, a faciley fabricated composite hole transport layer composed of unzipped single-walled carbon nanotubes (uSWNTs) and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) is effectively applied for PSC devices. Compared with the pure PEDOT:PSS hole transport layer (HTL) without uSWNTs, the uSWNTs/PEDOT:PSS layer shows more effective performance as the hole transportation layer. Optimizing the uSWNT concentration in PEDOT:PSS results in fabrication of the PSC devices with uSWNTs/PEDOT:PSS hole transport layers that exhibit greatly improved average power conversion efficiency (PCE), from 13.72% to 14.60%, and greatly enhanced current density and fill factor, which can be ascribed to the increased conductivity and hole transport efficiency. Our approach also supports simple solution-processing techniques and the insensitivity of the performance to thickness, which promises that the faciley fabricated uSWNTs/PEDOT:PSS layer has more potential to be applicable to the roll-to-roll process of PSC fabrication with extremely low cost.

Synthesis of catalase-inorganic hybrid nanoflowers via sonication for colorimetric detection of hydrogen peroxide.

A catalase-inorganic hybrid nanoflowers (Cat-HNFs)-based colorimetric platform was prepared for visual detection of hydrogen peroxide (H2O2). Catalase via coordination was self-assembled and embedded in the copper phosphate crystals by sonication. Under the designed colorimetric system, Cat-HNFs showed linear absorbance responses toward H2O2 in the concentration range of 1 µM to 1 mM, and the detection limit was 1 µM. Compared to free catalase, Cat-HNFs exhibited enhanced activity and stability for H2O2 detection. Moreover, after 5 cycles via centrifugal recovery, Cat-HNFs still remained 68% of their initial activity. The detection result in human serum suggested Cat-HNFs can be a promisng candidate for the detection of H2O2 in biomedical field.

Photodeposition of palladium nanoparticles on a porous gallium nitride electrode for nonenzymatic electrochemical sensing of glucose.

A nonenzymatic electrochemical glucose sensor is described that was obtained by in situ photodeposition of high-density and uniformly distributed palladium nanoparticles (PdNPs) on a porous gallium nitride (PGaN) electrode. Cyclic voltammetric and chronoamperometric techniques were used to characterize the performance of the modified electrode toward glucose. In 0.1 M NaOH solution, it has two linear detection ranges, one from 1 µM to 1 mM, and another from 1 to 10 mM, and the detection limit is 1 µM. The electrode is repeatable, highly sensitive, fast and long-term stable. It was applied to the quantitation of serum glucose where it displayed accurate current responses. Graphical abstract A novel nonenzymatic electrochemical glucose sensor was developed by in situ photodeposition of palladium nanoparticles on the porous gallium nitride electrode.

A ZnO/porous GaN heterojunction and its application as a humidity sensor.

A heterojunction of ZnO/porous GaN (ZnO/PGAN) was fabricated and directly applied to a diode-type humidity sensor. ZnO disks were loaded onto PGAN using a spraying process. The structure and surface morphology of the ZnO/PGAN were characterized using X-ray diffraction and scanning electron microscopy. The heterojunction displayed an excellent diode nature, which was investigated using photoluminescence spectra and I-V characteristics. The excellent transport capability of ZnO/PGAN contributes to enhanced electron transfer, and hence results in high sensitivity and quick response/recovery properties under different relative humidity (RH) levels. In the range of 12-96% RH, a fast sensing response time as low as 7 s and a recovery time of 13 s can be achieved. The simple design of a ZnO/PGAN based humidity sensor highlights its potential in various applications.

Direct physical vapor deposition and flexible photoelectrical properties of large-area free-standing films of metal octaethylporphyrin on ionic liquid surface.

Free-standing films of metal octaethylporphyrins (MOEPs) were prepared for the first time by a physical vapor deposition on surface of an ionic liquid (IL). Different from those on solid surfaces, the as-obtained films were very compact and with plannar structure. The monitoring of time-dependent process indicated that the high surface energy of IL and the strong π…π interaction between MOEP molecules played key roles in forming such films. Furthermore, the as-obtained film showed good transferability, which made it possible to be easily transferred to any substrates for further device application. More importantly, the prototype photodetectors based on free-standing films of MOEP showed ultra flexibility, mechanical stability, and durability.

Electrosynthesis of bismuth nanodendrites/gallium nitride electrode for non-enzymatic hydrogen peroxide detection.

Bismuth nanodendrites (BiNDs) were electrodeposited on planar gallium nitride (GaN) electrode via a differential pulse voltammetric technique to fabricate the non-enzymatic hydrogen peroxide (H2O2) sensor. SEM images revealed that the as-obtained BiNDs had numerous dendrite sub-branches, whose diameters ranged from 136 to 152nm. The BiNDs/GaN electrode showed linear amperometric responses for H2O2 in the concentration range from 10µM to 1mM with the sensitivity of 60.0µAmM-1cm-2. Another linear range was from 1 to 10mM with the sensitivity of 23.3µAmM-1cm-2. The limit of detection (LOD) was 5µM with the signal-to-noise ratio of 3. The applicability of the sensor was investigated to the H2O2 detection in real samples such as fetal bovine serum and milk, and the sensor exhibited excellent anti-interference capacity. The achieved results indicate that the as-prepared BiNDs/GaN sensor with good reproducibility and long-term stability was promising for detecting H2O2 in practical environments.

Porous GaN electrode for anodic stripping voltammetry of silver(I).

Here we demonstrate porous GaN electrode can be applied for trace Ag(I) detection. Compared to traditional planar electrodes, porous GaN electrode can detect lower concentration of Ag(I) as it possesses more deposition sites (crystal defects) and larger surface area. Under the optimum conditions, porous GaN electrode shows a linear voltammetric response in the Ag(I) concentration range from 1 to 100ppb with the detection limit of 0.5ppb. Such an unmodified, high-porosity and chemically stable electrode is promising to operate in real samples.