The active copper-containing carbon nanodots were prepared by hydrothermal method, and then characterized by fluorescence spectroscopy and UV-visible absorption spectroscopy.Subsequently, a highly sensitive and selective electrochemical biosensor was fabricated on the basis of this synthesized carbon nanodots with electro-deposition technique.The electrode behavior was investigated by cyclic voltammetry, electrochemical impedance spectroscopy, and differential pulse voltammetry.Furthermore, the catalysis mechanism was studied.The experimental results indicated that the biosensor exhibited a strong electrocatalytic activity toward the oxidation of uric acid (UA).What′s more, the interference from ascorbic acid and dopamine was eliminated effectively.Under the optimum conditions, there were linear relationships between the anodic peak current and the concentration of UA (1.00-300.0 μmol/L), and the limit detection was 0.30 μmol/L (S/N=3).The prepared biosensor had advantages such as easy fabrication, strong anti-interference ability, high sensitivity, and wide detection range, and could be used for real sample detection.

BACKGROUND: In lumbar spondylolisthesis patients with severe osteoporosis, screw is easily loose and pul s out during reposition, or loss of reduction and internal fixation failure easily occur after repair. Therefore, it is very important to elevate the intensity of pedicle screw fixation during repair. At present, few studies concern application of bone cement screw enhancement technology in lumbar spondylolisthesis patients with osteoporosis. OBJECTIVE: To investigate the clinical value of augmented pedicle screw with polymethylmethacrylate for lumbar spondylolisthesis accompanied with osteoporosis. METHODS: From June 2009 to June 2011, 27 patients suffering from lumbar spondylolisthesis accompanied with osteoporosis were included in this retrospective study. These patients received augmented pedicle screw with polymethylmethacrylate. The levels of disability and pain were evaluated by Oswestry Disability Index and visual analog scale. The internal fixation and fusion were evaluated by radiological findings. Al complications were recorded. RESULTS AND CONCLUSION: Al cases were fol owed up for 15-37 months. Oswestry Disability Index and visual analog scale scores were significantly better in final fol ow-up than that pre-treatment (P < 0.05). Imaging results revealed that bone cement tightly connected to bone interface. The position of screw and bone cement was good. Symptomatic bone cement leakage was not found. No fixation failure was detected during final fol ow-up. Al patients achieved interbody fusion. These results suggested that polymethylmethacrylate bone cement could increase the gripping force of the pedicle screw in osteoporotic vertebral body. It is safe and effective to treat spondylolisthesis accompanied with osteoporosis with augmented pedicle screws. Satisfactory fixation stability and interbody fusion can be obtained.