Mei Jywan Syu

Biological production of 2,3-butanediol

Abstract. 2,3-Butanediol (2,3-BDL), which is very important for a variety of chemical feedstocks and liquid fuels, can be derived from the bioconversion of natural resources. One of its well known applications is the formation of methyl ethyl ketone, by dehydration, which can be used as a liquid fuel additive. This article briefly reviews the basic properties of 2,3-BDL and the metabolic pathway for the microbial formation of 2,3-BDL. Both the biological production of 2,3-BDL and the variety of strains being used are introduced. Genetically improved strains for BDL production which follow either the original mechanisms or new mechanisms are also described. Studies on fermentation conditions are briefly reviewed. On-line analysis, modeling, and control of BDL fermentation are discussed. In addition, downstream recovery of 2,3-BDL and the integrated process (being important issues of BDL production) are also introduced.

Synthesis of an Imprinted Hybrid Organic−Inorganic Polymeric Sol−Gel Matrix Toward the Specific Binding and Isotherm Kinetics Investigation of Creatinine

Hybrid organic-inorganic polymeric sol-gel materials imprinted with creatinine template molecules were synthesized for the specific binding of creatinine. Creatinine is a metabolite from creatine and is the final product from kidney metabolism. Therefore, creatinine can be an important index to estimate the function of the kidney. It was then chosen as the target molecule in this work. To achieve the specific binding toward creatinine, molecular imprinting was used to create a polymeric matrix for the regarding purpose. Sol-gel was further added to create a rigid network structure for the absorption of creatinine. An inorganic precursor, tetraethoxysilane (TEOS), was mixed with an organic functional monomer, 2-acrylamido-2-methylpropane-sulfonic acid (AMPS), and the creatinine template to form a hybrid organic-inorganic imprinted polymer. The chemical functionality was achieved as well as a confined matrix via the polymerization and the hydrolysis-condensation of the sol-gel. The imprinting effect from the hybrid materials against the corresponding nonimprinted was investigated. BET (Brunauer-Emmett-Teller) analysis was carried out for the imprinted and the nonimprinted materials. The specificity of the hybrid materials was further examined by capping the surface silanol groups with chloro-trimethylsilane (CTMS) and 1,1,1,3,3,3-hexamethyldisilazane (HMDS), respectively. The capping effect was compared and discussed from the binding results. Selectivity of the materials toward creatinine was obtained using mixture solutions in the presence of creatinine and its analogues. Reutilization and storage stability of the hybrid organic-inorganic imprinted material were also studied. Additionally, the affinity distribution of the hybrid imprinted materials derived from the allosteric model was also analyzed from the adsorption isotherm data.

A study on the α-amylase fermentation performed by Bacillus amyloliquefaciens

Abstract α -Amylase fermentation with soluble starch as the limiting substrate was performed by Bacillus amyloliquefaciens . We investigated the influence, of the presence of α -amylase, on the hydrolysis of different starch concentrations. Both the initial and average rates for the hydrolysis of starch under different initial conditions were compared and calculated. The time for the completion of starch hydrolysis was also obtained. Effects of kinetic factors, such as pH of 5.5, 6.3, 7.0 and temperature of 30 °C and 37 °C, on the performance of α -amylase fermentation were studied. The influence of the dynamic variables, such as agitation speed and aeration rate, on this fermentation were also evaluated and are discussed. The variations of cell mass, α -amylase activity, and reducing sugar with regard to the step changes of aeration rates during a batch fermentation are also discussed. The optimal conditions of these variables have been determined.

Ionic effect investigation of a potentiometric sensor for urea and surface morphology observation of entrapped urease/polypyrrole matrix

Potentio-dynamic polymerization of buffered urease and pyrrole monomer onto carbon papers was conducted to fabricate an immobilized urease electrode for measuring the urea concentration. To use carbon paper as the substrate for the electro-growth of polypyrrole matrix not only created sufficient adhesion of the conducting polymer layer but also provided superior entrapment of urease enzymes. The potentiometric response corresponding to ammonia, the product formed from the urease catalyzed urea reaction, was employed for the urea concentration measurement. Scanning electron microscopic photographs showed that the polypyrrole matrix deposited on the carbon papers appeared to be of a cylindrical nanotube shape. The charge density applied in the polymerization was found to affect the potentiometric response while the potential-scanning rate showed minor influence. The composite electrodes had high sensitivity in urea detection, showing a response linear to the logarithm of the urea concentration in the range of 10(-3) to 10 mM. The detection of urea solution prepared in water and buffer was also compared. Ionic effect on the sensing of urea solution was investigated. By comparing the data reported in literature, the urease/polypyrrole/carbon paper electrode developed in this work showed superior long-term stability and reusability. The detection of urea in serum was also well performed.

Via zinc(II) protoporphyrin to the synthesis of poly(ZnPP-MAA-EGDMA) for the imprinting and selective binding of bilirubin

Poly(zinc protoporphyrin-methacrylic acid-ethyl glycol dimethylacrylate) (poly(ZnPP-MAA-EGDMA)) imprinted with alpha-bilirubin can cause spectroscopic change in wavelength and absorption intensity due to the metal-ion coordination between ZnPP and bilirubin. The fluorescent imprinted polymer was able to selectively bind alpha-bilirubin. The corresponding imprinted polymer monolith was synthesized by using the functional monomer, methacrylic acid and the fluorescent monomer, zinc(II) protoporphyrin. Although the imprinted polymers (MIPs) using methacrylic acid, protoporphyrin, or zinc(II) protoporphyrin alone as the only functional monomer could bind bilirubin, the imprinting effects were all comparably inferior to the imprinted poly(ZnPP-MAA-EGDMA). Therefore, it revealed that via the combined utilization of ZnPP and MAA for the fluorescent and functional effect, the MIPs thus prepared were then able to create the highly selective cavities. The optimal condition for the heated polymerization of the imprinted poly(ZnPP-MAA-EGDMA) was found to be 60 degrees C for 6 h. The imprinting factor of 3.069 could be achieved from the fluorescent imprinted polymer by comparing the binding results obtained from the MIP and the NIP (non-imprinted polymer). The imprinting factor obtained from bilirubin/biliverdin mixture solution was reduced to 2.111 because of the presence of biliverdin. The selectivity toward bilirubin of 2.269 from the bilirubin/biliverdin mixture was obtained. Therefore, to utilize ZnPP for the preparation of the imprinted materials confirmed the selective binding and detection of bilirubin via the fluorescent approach.

Towards bilirubin imprinted poly(methacrylic acid-co-ethylene glycol dimethylacrylate) for the specific binding of α-bilirubin

With α-bilirubin as a molecular template, polymerization of methacrylic acid (MAA) was carried out with the aid of the initiator 2,2-azobisisobutyronitrile (AIBN) and the cross-linking agent ethylene glycol dimethylacrylate (EGDMA). Bulk polymerization was successfully carried out so that poly(methacrylic acid-co-ethylene glycol dimethylacrylate) (poly(MAA-EGDMA)) imprinted with α-bilirubin was first developed. UV irradiation polymerization and heated polymerization methods were compared. Effect of different ratios of monomer to EGDMA during the polymerization was also discussed. Proper solvent for better desorption of α-bilirubin from the imprinted poly(MAA-EGDMA) was investigated. In addition, SEM photos were provided for observing the differences between the surfaces of the imprinted poly(MAA-EGDMA) before and after extraction. The corresponding binding results of α-bilirubin imprinted poly(MAA-EGDMA) and non-imprinted poly(MAA-EGDMA) both after extraction were compared. How the pH values during extraction stage affected the binding capacities of the imprinted polymer as well as non-imprinted polymer were also discussed. Similar study and comparison were made for different binding pH values. Different compounds of similar molecular weight were used to show the specific binding of the imprinted polymer for bilirubin. The results further confirmed the successful binding as well as specificity of the imprinted poly(MAA-EGDMA) for α-bilirubin.

A multi-functional electrochemical sensing system using microfluidic technology for the detection of urea and creatinine.

This study presents a new microfluidic system capable of precise measurements of two important biomarkers, urea and creatinine, automatically. In clinical applications, high levels of these two biomarkers are early indicators of nephropathy or renal failure and should be monitored on a regular basis. The microfluidic system is composed of a microfluidic chip, a control circuit system, a compressed air source and several electromagnetic valves to form a handheld system. The microfluidic chip is fabricated by using micro‐electromechanical systems and microfluidic techniques comprising electrochemical sensor arrays and polydimethylsiloxane‐based microfluidic structures such as micropumps/micromixers, normally closed valves and microchannels. The microfluidic system performs a variety of critical processes including sample pretreatment, mixing, transportation and detection on a single chip. The experimental results show that the entire procedure takes approximately 40 min, which is much faster than the traditional method (more than 6 h). Furthermore, the total sample volume consumed in each operation is only 0.1 mL, which is significantly less than that required in a large system (5 mL). The developed automatic microfluidic system may provide a powerful platform for further clinical applications.

Diagnostic role of biliary pancreatic elastase for cholangiocarcinoma in patients with cholestasis

BACKGROUND A wide array of proteins is secreted into the bile and may be associated with biliary tract diseases. We attempted to discover novel biomarker in bile for cholangiocarcinoma. METHODS Bile was collected from patients with bile duct obstruction. Proteins were separated by 2-dimensional electrophoresis and identified by mass spectrometry. Levels of mRNA and protein expression of the candidate biomarker were analyzed by real-time PCR and Western blotting, respectively, whereas enzyme activity was measured by a kinetic method. The diagnostic efficacy was assessed by receiver operating characteristic (ROC) curve analysis. RESULTS Pancreatic elastase (PE) 3B was identified as a biomarker for cholangiocarcinoma. The mRNA of PE 3B was up-regulated in cancerous tissues, compared to non-cancerous tissues. The protein expression and enzyme activity of PE in bile were increased in patients with cholangiocarcinoma, compared to gallstone patients. Biliary amylase activity was used to correct the presence of pancreaticobiliary reflux. Significantly higher PE/amylase ratios in bile were found in patients with cholangiocarcinoma (0.214+/-0.045) than those with gallstone (0.023+/-0.005, p<0.001). The area under the ROC curve of the ratio was 0.877 (95% CI: 0.765 to 0.988). Using 0.065 as a cutoff value, the ratio distinguished malignant from benign causes of biliary obstruction with a sensitivity of 82% and a specificity of 89%. CONCLUSION PE in bile is a biomarker for cholangiocarcinoma and the combination measurement of PE and amylase enhances diagnostic efficacy.

Headgroup effects of template monolayers on the adsorption behavior and conformation of glucose oxidase adsorbed at air/liquid interfaces

Stearic acid (SA) and octadecylamine (ODA) monolayers at the air/liquid interface were used as template layers to adsorb glucose oxidase (GOx) from aqueous solution. The effect of the template monolayers on the adsorption behavior of GOx was studied in terms of the variation of surface pressure, the evolution of surface morphology observed by BAM and AFM, and the conformation of adsorbed GOx. The results show that the presence of a template monolayer can enhance the adsorption rate of GOx; furthermore, ODA has a higher ability, compared to SA, to adsorb GOx, which is attributed to the electrostatic attractive interaction between ODA and GOx. For adsorption performed on a bare surface or on an SA monolayer, the surface pressure approaches an equilibrium value (ca. 8 mN/m) after 2 to 3 h of adsorption and remains nearly constant in the following adsorption process. For the adsorption on an ODA monolayer, the surface pressure will increase further 1 to 2 h after approaching the first equilibrium pressure, which is termed the second adsorption stage. The measurement of circular dichroism (CD) spectroscopy indicates that the Langmuir-Blodgett films of adsorbed GOx transferred at the first equilibrium state (π = 8 mN/m) have mainly a β-sheet conformation, which is independent of the type of template monolayers. However, the ODA/GOx LB film transferred at the second adsorption stage has mainly an α-helix conformation. It is concluded that the specific interaction between ODA and GOx not only leads to a higher adsorption rate and adsorbed amount of GOx but also induces a conformation change in adsorbed GOx from β-sheet to α-helix. The present results indicate that is possible to control the conformation of adsorbed protein by selecting the appropriate template monolayer.

Neural network signal detection of an SO2 electrode

A novel SO2 electrode made from polyaniline/Nafion membrane was developed. The electrode was designed to detect SO2 content at ppm levels from the exhaust gas of factories. An SO2 concentration of 20–250 ppm was measured through a response current and a neural network was introduced to learn the response signal and predict the SO2 concentration. By providing the whole pattern of the response currents at different sampling times as input nodes of the network, the corresponding SO2 concentration can be learned and predicted as the output of the network. Such a parallel approach is different from the conventional calibration method. The latter takes 6 min to reach a steady response. Neural network signal pattern detection does not necessarily require a steady response, and as a result, the response time could be reduced to 3 min. The amplified signal in the conventional calibration method often requires a noise filter which is not necessary for the neural network approach because of its fault tolerance ability. A saturation-type transfer function bx/(1+|x|) was chosen and excellent results were obtained. Response currents acquired at different sampling intervals corresponding to different numbers of input nodes, were compared by examining the training and prediction ability of the neural network. The minimum number of training data for accurate predictions was also determined.