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.

Objective:To investigate the expression level of circular RNA circ_0020123 in ovarian cancer (OC) , and then to evaluate the diagnostic value of circ_0020123 level in ovarian cancer.Methods:Fifty-five ovarian cancer patients who were diagnosed and treated in Hangzhou Linping District Maternal and Child Health Hospital from Oct. 2016 to Mar. 2017 were selected, and serum was collected for high-throughput gene expression sequencing analysis. The circ_0020123 level in serum of ovarian cancer patients and healthy controls was determined by real-time quantitative PCR, and the diagnostic efficacy of circ_0020123 level on ovarian cancer was evaluated by drawing receiver operating characteristic curve (ROC) . The correlation between the expression of circ_0020123 and the clinical characteristics of ovarian cancer patients was investigated by t-test. The survival curve was drawn to analyze the relationship between the serum circ_0020123 level and the prognosis and survival of ovarian cancer patients. Western blot was used to detect the expression levels of autophagy-related proteins LC3-II/LC3-I and p62.Results:Compared with the serum of healthy people (1±0.25) , the expression of circ_0020123 was significantly up-regulated in the serum of ovarian cancer patients (1.24±0.23) ( t=5.23, P<0.001) . The ROC curve showed that circ_0020123 had high diagnostic performance for the detection of ovarian cancer specimens (AUC=0.7579, P<0.001) . Comprehensive analysis of t test and logistic analysis showed that the high expression of circ_0020123 was significantly correlated with FIGO stage ( t=5.46, P<0.001) and tumor size ( t=6.37, P<0.001) . The measurement of survival data showed that the 5-year overall survival of the circ_0020123 high expression group was significantly shorter than that of the circ_0020123 low expression group ( P=0.019) . Knockdown of circ_0020123 in cells down-regulated the expression of autophagy-related proteins LC3-II/LC3-I (0.45±0.05) ( t=9.31, P=0.001) , and up-regulated the expression of p62 (1.94±0.11) ( t=12.62, P<0.001) . Conclusion:The results of this study indicate that circ_0020123 is an important ovarian cancer-related circular RNA, which provides a potential diagnostic, prognostic biomarker and therapeutic target for ovarian cancer patients.