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A survey was done recently in Jiaxing city of Zhejiang Province in the Yangtze River Delta to compare the differences of soil microbiological properties among paddy soils with different land use including continuous open-field vegetable cultivation (OFVC), plastic-greenhouse vegetable cultivation (PGVC) and traditional rice-wheat rotation (RWR). The soil types included are percolating, permeable and waterlogged paddy soils. The results indicate that the microbial flora was markedly changed as the land use changed for all the three soil types. In continuous vegetable cultivation soils, especially in PGVC soils, the bacteria amounts decreased dramatically, but the fungal and actinomyce amounts increased as compared with RWR soils. The dehydrogenase activities decreased significantly in vegetable soils, especially in PGVC soils as compared with RWR soils. The microbial biomass C and the total phospholipid contents (TPL) in vegetable cultivation soil greatly decreased as compared with RWR soils. Biolog analysis indicated that the kinds of carbon sources that could be metabolized by native microbes in PGVC soils greatly decreased as compared with OFVC soils and RWR soils, revealing that microbial diversity had decreased since land use change. The activities of some soil enzymes including urease, invertase and phosphase were all lower in OFVC soils than those in RWR soils, and those in PGVC soils were the lowest. The degradation of microbiological activities in continuous vegetable cultivation soils, especially in PGVC soils, as compared with RWR soils might have been caused by soil acidification and accumulation of salts due to overuse of both organic and inorganic fertilizers in vegetable cultivation.

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A new electrochemical immunosensing protocol for sensitive detection of alpha-fetoprotein (AFP, as a model) in human serum was developed by means of immobilization of horseradish peroxidase-anti-AFP conjugates (HRPanti-AFP) onto graphene and nanogold-functionalized biomimetic interfaces. The low-toxic and high-conductive graphene complex provided a large capacity for nanoparticulate immobilization and a facile pathway for electron transfer. With a one-step immunoassay format, the antigen-antibody complex was formed between the immobilized HRP-anti-AFP on the electrode and AFP in the sample. The formed immunocomplex was coated on the electrode surface, inhibited partly the active center of HRP, and decreased the catalytic reduction of HRP toward the enzyme substrate of H 2 O 2 . Under optimal conditions, the decrease of reduction currents was proportional to AFP concentration, and the dynamic range was 1.0-10 ng/mL with a relative-low detection limit (LOD) of 0.7 ng/mL AFP. Intra-and inter-assay coefficients of variation (CVs) were less than 10 %. The assay was evaluated for clinical human serum samples, including 8 (possible) patients with hepatocarcinoma and 3 normal human sera. Correct identification of negative/positive samples and perfect accordance with results from Elecsys 2010 Electrochemiluminescent Automatic Analyzer as a reference was obtained. Importantly, the graphene and nanogold-based sensor provided a promising platform for the detection of other biocompounds, and could be further applied for development of other potential electrochemical bio/chemosensors.