共查询到8条相似文献,搜索用时 15 毫秒
1.
Abdullah J Ahmad M Heng LY Karuppiah N Sidek H 《Analytical and bioanalytical chemistry》2006,386(5):1285-1292
The stacked-film immobilization of 3-methyl-2-benzothiazolinone hydrazone (MBTH) in hybrid nafion/sol-gel silicate film and
horseradish peroxidase (HRP) in chitosan, performed in order to allow the determination of phenolic compounds, was investigated
via an optical method. The stacked films were deposited onto a microscope glass slide by a spin-coating technique. The quinone
or free radical product formed by the enzymatic reactions of phenolic compounds interacts with MBTH to form azo-dye products,
which can be measured spectrophotometrically at a wavelength of 500 nm. The color intensity of the product was found to increase
in proportion to the phenolic concentration after 5 min of exposure. The response of the biosensor was linear over concentration
ranges of 0.025–0.500, 0.010–0.070 and 0.050–0.300 mM for guaiacol, resorcinol and o-cresol, respectively, and gave detection limits of 0.010, 0.005 and 0.012 mM. The sensor exhibited good sensitivity and stability
for at least two months. 相似文献
2.
Ting Zhang 《Analytica chimica acta》2003,489(2):199-206
A novel inorganic-organic hybrid titania sol-gel nanocomposite film was prepared to fabricate a sensitive tyrosinase biosensor for the amperometric detection of trace phenolic compounds without additional electron mediators. Acetylacetone worked as a complexing ligand to chelate with Ti atom in the synthesis process, and the pH of the titania solution could be adjusted to the value which was optimum for retaining tyrosinase activity and such a membrane was stably attached on to the surface of a glassy carbon electrode (GCE). This titania matrix could supply a good environment for enzyme loading, which resulted in a high sensitivity of 15.78 μA μM−1 cm−2 for monitoring phenols with a detection limit of 1×10−8 M at a signal-to-noise ratio of 3. The TiO2 sol-gel derived biosensor exhibited a fast response less than 10 s and a good stability for more than 2 months. 相似文献
3.
Min Ah Kim 《Analytica chimica acta》2003,479(2):143-150
An amperometric biosensor based on tyrosinase immobilized in silicate/Nafion composite film has been developed for the determination of phenolic compounds. The Nafion polymer in the composite was used not only to overcome the brittleness of the pure sol-gel-derived silicate film but also to increase the long-term stability of the biosensor. Tyrosinase was immobilized by a thin film of silicate/Nafion composite on a glassy carbon electrode. Phenolic compounds were determined by the direct reduction of biocatalytically-liberated quinone species at −200 mV versus Ag/AgCl (3 M NaCl). The process parameters for the fabrication of the enzyme electrode and various experimental variables such as pH and operating potential were explored for optimum analytical performance of the enzyme electrode. The biosensor can reach 95% of steady-state current in about 15 s. The sensitivities of the biosensor for catechol and phenol were 200 and 46 mA/M, respectively. A detection limit of 0.35 mM catechol was obtained with a signal-to-noise ratio of 3. The enzyme electrode retained 74% of its initial activity after 2 weeks of storage in 50 mM phosphate buffer at pH 7. 相似文献
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5.
Developing a biosensor which is capable of simultaneously monitoring l-Dopa levels in multiple samples besides requiring small reaction volume is of great value. The present study describes the detection of l-Dopa using tyrosinase enzyme extracted from Amorphophallus campanulatus and immobilized on the surface of the microplate wells. Among the different approaches used for immobilizing tyrosinase onto the microplate wells, glutaraldehyde treatment was found to be most effective. Besides enzyme activity, ESEM–EDS (environmental scanning electron microscope–energy dispersive system) and Atomic Force Microscopy (AFM) were also carried out to confirm the immobilization of tyrosinase enzyme onto the microplate well surface. This immobilized biocomponent was then integrated with an optical transducer for l-Dopa detection and it showed good reproducibility. The sensing property of the system was studied by measuring the initial rate of dopachrome formation at 475 nm. The calibration plot gave a linear range of detection from 10–1000 μM and the detection limit was calculated to be 3 μM. The immobilized biocomponent was stable for 41 days and was reused up to nine times. Spiked samples (blood plasma) were also analyzed using this biocomponent. This microplate based biosensor thus provides a convenient system for detection of multiple samples in a single run. 相似文献
6.
Tyrosinase from a plant source Amorphophallus companulatus was immobilized on eggshell membrane using glutaraldehyde. Among the three different approaches used for immobilization, activation of eggshell membrane by glutaraldehyde followed by enzyme adsorption on activated support could stabilize the enzyme tyrosinase and was found to be effective. Km and Vmax values for dopamine hydrochloride calculated from Lineweaver-Burk plot were 0.67 mM and 0.08 mM min−1, respectively. Studies on effect of pH showed retention of more than 90% activity over a pH range 5.0-6.5. Membrane bound enzyme exhibited consistent activity in the temperature range 20-45 °C. Shelf life of immobilized tyrosinase system was found to be more than 6 months when stored in phosphate buffer at 4 °C. An electrochemical biosensor for dopamine was developed by mounting the tyrosinase immobilized eggshell membrane on the surface of glassy carbon electrode. Dopamine concentrations were determined by the direct reduction of biocatalytically liberated quinone species at −0.19 V versus Ag/AgCl (3 M KCl). Linearity was observed within the range of 50-250 μM with a detection limit of 25 μM. 相似文献
7.
溶胶-凝胶壳聚糖/二氧化硅杂化复合膜固定辣根过氧化酶的H2O2电化学生物传感器的研制 总被引:8,自引:0,他引:8
利用溶胶 凝胶法制备壳聚糖 二氧化硅有机无机复合杂化膜,用于对辣根过氧化酶进行固定,制得测定H2O2的电流型生物传感器。以1mmol/LK4Fe(CN)6作为电子媒介体。研究了各种因素如壳聚糖与二氧化硅的比率、pH、温度、工作电位等对传感器响应电流的影响。计时电流法测定H2O2的线性范围为2.0×10-6~6.8×10-4mol/L,检出限为8.0×10-7mol/L。测得酶催化动力学参数米氏常数Km=0 87mmol/L。用该法对实际样品进行了测定。 相似文献
8.
Wenxiu Que L. L. Wang T. Chen Z. Sun X. Hu 《Journal of Sol-Gel Science and Technology》2006,38(2):147-152
GeO2/organically modified silane organic-inorganic hybrid materials derived by a sol-gel technique were studied for optical waveguide
applications. Acid-catalyzed solutions, firstly, γ-glycidoxypropyltrimetho-xysilane mixed with germanium isopropoxide, and
secondly, methyltrimethoxysilane mixed with germanium isopropoxide were used as precursors. Optical and structural properties
of the waveguide thin films prepared from the two types of sols were characterized by using the prism coupling technique,
atomic force microscopy, thermal gravimetric analysis, UV-visible spectroscopy, and Fourier transform infrared. The obtained
results indicate that in both cases, crack-free and highly transparent waveguide thin films with a thickness of more than
2-μm could be obtained by a single spin-coating process and at a low-temperature heat treatment of 100°C. A strong UV absorption
region at short wavelength ∼200 nm, accompanied with a shoulder peaked at ∼240 nm, was also identified. It has been experimentally
demonstrated that a channel waveguide structure could easily be fabricated from the hybrid sol-gel thin films by using reactive
ion etching. 相似文献