A novel enzyme-free biosensor based on porous metal organic frame nanocomposites, i.e., core–shell structured Au@NC@GC nanocomposites, has been constructed for simultaneous determination of uric acid (UA) and dopamine (DA). Au@ZIF-8@ZIF-67 was prepared through a seed-mediated growth method and carbonized in nitrogen atmosphere to synthesize a nanoporous hybrid carbon materials (Au@NC@GC). Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) studies demonstrate that the as-prepared Au@NC@GC modified glassy carbon electrode (Au@NC@GC-GCE) possesses a high selectivity and sensitivity for simultaneous detections of UA and DA. It exhibited wide linear responses for UA and DA in the range from 10 μM to 600 μM and 10 μM to 150 μM, with the detection limits of 0.773 nM and 0.746 nM, respectively (S/N = 3). Moreover, this novel electrochemical biosensor could be further utilized in biological analysis (i.e., human serum), and the satisfactory recovery results of UA and DA could be readily obtained. These afore-mentioned results further manifest that the as-prepared biosensors are capable for quantitatively monitoring UA and DA in serum, verifying the possibility for its future promising applications in real biological or clinic samples analysis.
Poly (ether ester) elastomer, a segmented copolymer, recently has attracted a wide attention for its unique properties such as elasticity, low temperature impact resistance and chemistry resistance. In this work, a range of poly (ether ester) s were synthesized via a two-step polymerization method using poly (ethylene terephthalate) (PET) as rigid segment and poly (ethylene glycol) (PEG) as flexible segment. The effects of the molecular weight (1000-8000 g/mol) and the weight ratios with PEG (30/100-70/100) of PET segments on the performance of synthetic copolymers were investigated. The chemical structure, thermal properties and hydrophilic performance of the copolymers were respectively characterized. Additionally, the practical block ratios of PEG/PET were calculated by the 1H-NMR Spectra of the copolymer after Soxhlet extraction. Through the obtained results, it revealed that increasing the molecular weight or content of PEG could enhance the hydrophilic performance of the copolymers and reversely reduce its thermal stability. It was shown that the reactivity of PEG in the polymerization process was weakened when its molecular weight was above 4000 or weight ratio with PTA was higher than 60/100, subsequently affected the practical block ratios of PEG/PET in the resulting poly(ether ester)elastomers.
Due to its excellent mechanical property, dye ability and skin affinity, PA6 has been widely used in apparel, home textiles, military products, etc. However, PA6 fiber is easy to breed bacteria and corroded by bacteria in humid environment. One of development tendency of functional PA6 fiber is to design and develop nylon 6 fiber with excellent antibacterial properties, which is also the research target of this paper. In the present investigation, ZnO antibacterial agent was prepared through sol-gel method, and antibacterial masterbatch was acquired via blending antibacterial agent with PA6 using a twin-screw, then antibacterial PA6 fiber was obtained through melt spinning. The thermal properties, crystallization property of antibacterial PA6 masterbatch were discussed. The effect of drawing ratio on fiber strength, elongation of break, orientation and crystallization was also investigated. The antibacterial properties of antibacterial agent and antibacterial PA6 fiber was analyzed by agar diffusion method. The results of Differential Scanning Calorimetry (DSC) suggests that the antibacterial agent causes the rise of crystallization temperature and crystallization rate. X-Ray Diffraction (XRD) and mechanical testing results reveal that the higher drawing ratio leads to higher orientation and strength of PA6 fiber, lower elongation at break. The addition of antibacterial agent increases the degree of orientation and crystallization, reduces the strength of fiber and tends to form α crystalline in PA6 fiber. Antibacterial tests show that antibacterial PA6 fiber has a good antibacterial performance against Staphylococcus aureus.
In this study, biomimetic synthesis of hydroxyapatite (HAp) nanocomposites based on bacterial cellulose (BC) with sodium alginate (SA) surface modification was studied. The results showed that SA treatment promoted the apatite nucleation ability of BC in SBF solution. The FE-SEM images demonstrated that HAp nanoparticles were successfully formed in the three dimensional nanofiber network of BC. FTIR spectra indicated that the obtained HAp crystals were partially substituted with carbonate, which were very similar with natural bones. It was also found that both of crystallite size and crystallinity of HAp crystals observed from XRD pattern were very low. The resultant nanocomposites consisted of nano-scale HAp crystals and SA treated BC nanofibrous have great potential application in bone tissue engineering.
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