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ABSTRACT: A new kind of biosensor for the detection of urea with a high selectivity, sensitivity and wide detection range was designed based on the secretion of carnation petals cells paste covered over a graphite-epoxy composite basic electrode surface. The carnation petal paste from mashed fresh carnation petals was tightly fixed on the basic electrode surface with Teflon thin film to keep it in contact with the electrode surface. Urea in aqueous solution was detected by differential pulse voltammetry based on the oxidation peak current at 0.316 V (vs. SCE) of the secreted species of carnation petal cells during the mashing process, which interacts with urea molecules and results in the decrease of the oxidation peak current. The oxidation peak current decreases linearly with the logarithm of urea concentration in the range of 1.3 × 10(-16)-4.57 × 10(-8) M and 3.4 × 10(-7)-1.3 × 10(-1) M with a detection limit of 7.5 × 10(-16) M. The biosensor was characterized by electrochemistry and fluorescent spectrometry, and applied to the determination of urea in waste water from a river around Shenyang Normal University campus with a recovery of 104.5% (RSD is 5.00%). The presence of larger amounts of ammonium ion and nitrate ion up to the molar ratio of 10(4) do not interfere with the urea detection.
The Analyst 02/2011; 136(4):841-6. · 4.23 Impact Factor
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ABSTRACT: For elucidating the regulatory mechanism of ethylene on carotenoid-related volatiles (open chain) compounds and the relationship between lycopene and carotenoid-related volatiles, transgenic tomato fruits in which ACC synthase was suppressed were used. The transgenic tomato fruit showed a significant reduction of lycopene and aroma volatiles with low ethylene production. 6-Methyl-5-hepten-2-one, 6-methyl-5-hepten-2-ol and geranylacetone, which were suspected to be lycopene degradation products, were lower than those in wild type tomato fruits. In order to identify whether lycopene accumulation effects the biosynthesis of some carotenoid-related volatiles independent of ethylene in tomato or not, the capability of both wild type and transgenic tomato fruits discs to convert lycopene into carotenoid-related volatiles was evaluated. The data showed that external lycopene could convert into 6-methyl-5-hepten-2-one and 6-methyl-5-hepten-2-ol in vivo, indicating that the strong inhibition of ethylene production had no effect on enzymes in the biosynthesis pathway of some carotenoid-related volatiles. Therefore, in ACS-suppression transgenic tomato fruits, the low levels of 6-methyl-5-hepten-2-one, 6-methyl-5-hepten-2-ol was due to decreased lycopene accumulation, not ethylene production. Ethylene only affected the accumulation of lycopene, and then indirectly influenced the level of lycopene-related volatiles.
Journal of Integrative Plant Biology 09/2008; 50(8):991-6. · 2.53 Impact Factor
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ABSTRACT: Microcantilevers (MCLs) hold a position as a cost-effective and highly sensitive sensor platform for medical diagnostics, environmental analysis and fast throughput analysis. MCLs are unique in that adsorption of analytes on the microcantilever (MCL) surface changes the surface characteristics of the MCL and results in bending of the MCL. Surface stress due to conformation change of proteins and other polymers has been a recent focus of MCL research. Since conformational changes in proteins can be produced through binding of anylates at specific receptor sites, MCLs that respond to conformational change induced surface stress are promising as transducers of chemical information and are ideal for developing microcantilever-based biosensors. The MCL can also potentially be used to investigate conformational change of proteins induced by non-binding events such as post-translational modification and changes in temperature or pH. This review will provide an overview of MCL biosensors based on conformational change of proteins bound to the MCL surface. The models include conformational change of proteins, proteins on membranes, enzymes, DNA and other polymers.
The Analyst 05/2008; 133(4):434-43. · 4.23 Impact Factor
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ABSTRACT: We have investigated the sensing performance of protein-based microcantilever biosensors prepared from multiple surface conjugation chemistries. The 11-mercaptoundecanoic acid monolayers were prepared according to both traditional and modified processes. In three protein-based biosensors, the modified process improved microcantilever sensing performance by increasing the bending amplitude, a critical step toward developing a cost-effective microcantilever-based sensor platform for medical diagnostics and environmental and drug screening applications. Scanning electron microscopy (SEM) images demonstrated that proteins immobilized on the microcantilever surface using the modified chemistry approach formed a compact layer.
Langmuir 02/2008; 24(2):345-9. · 4.19 Impact Factor
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ABSTRACT: A potential binding assay based on conformational-change-induced micromechanical motion is described. Calmodulin was used to modify a microcantilever (MCL) by a self-assembled layer-by-layer approach. The results showed that the modified MCL bent when the proteins changed their conformation upon binding with Ca2+. The cantilever deflection amplitudes were different under different ionic strengths, indicating different degrees of conformational change of the proteins in these conditions. On the contrary, cantilevers modified by proteins, such as hemoglobin and myoglobin, that do not change conformations upon binding with analytes do not cause the cantilever deflection. These results suggest that the conformational changes of proteins may be used to develop cantilever biosensors, and the MCL system has potential for use in label-free, protein-analyte screening applications.
Langmuir 01/2007; 22(26):11241-4. · 4.19 Impact Factor
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ABSTRACT: The prediction of inundated area helps to reduce flood-disaster damage efficiently by simulating the flood-spreading procedure. The principle and method of flood-spreading simulation were discussed. The needed surface-elevation model was built automatically from existing feature data by use of GIS. The models to simulate floodwater washing and floodwater storing were built using breadth-first-search algorithm. The detailed procedures were provided. The Hengren County of Liaoning Province was used as the study-area as an example. A flood was simulated with the Hengren Reservoir as the main floodwater source. The spatial analysis of GIS was used to predict and analyze the results. The simulating method provides supporting-decisions information for flood-disaster-defending department and base data for flood-disaster-evaluating department.
Intelligent Control and Automation, 2004. WCICA 2004. Fifth World Congress on; 07/2004
