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Plant development requires coordination among complex signaling networks to enhance the plant's adaptation to changing environments. DELLAs, transcription regulators originally identified as repressors of phytohormone gibberellin signaling, play a central role in integrating multiple signaling activities via direct protein interactions with key transcription factors. Here, we found that DELLA is mono-O-fucosylated by the novel O-fucosyltransferase SPINDLY (SPY) in Arabidopsis thaliana. O-fucosylation activates DELLA by promoting its interaction with key regulators in brassinosteroid- and light-signaling pathways, including BRASSINAZOLE-RESISTANT1 (BZR1), PHYTOCHROME-INTERACTING-FACTOR3 (PIF3) and PIF4. Moreover, spy mutants displayed elevated responses to gibberellin and brassinosteroid, and increased expression of common target genes of DELLAs, BZR1 and PIFs. Our study revealed that SPY-dependent protein O-fucosylation plays a key role in regulating plant development. This finding may have broader importance because SPY orthologs are conserved in prokaryotes and eukaryotes, thus suggesting that intracellular O-fucosylation may regulate a wide range of biological processes in diverse organisms.

In this study, a urea biosensor was prepared by the immobilization of urease onto the sensitive membrane of an extended-base bipolar junction transistor. The pH variation was used to detect the concentration of urea. The SnO2/ITO glass, fabricated by sputtering SnO2 on the conductive ITO glass, was used as a pH-sensitive membrane, which was connected with a commercial bipolar junction transistor device. The gels, fabricated by the poly vinyl alcohol with pendent styrylpyridinium groups, were used to immobilize the urease. This readout circuit, fabricated in a 0.35-um CMOS 2P4M process, operated at 3.3V supply voltage. This circuit occupied an area of 1.0 mm × 0.9 mm. The dynamic range of the urea biosensor was from 1.4 to 64 mg/dl at the 10 mM phosphate buffer solution and the sensitivity of this range was about 65.8 mV/pUrea. The effect of urea biosensors with different pH values was considered, and the characteristics of urea biosensors based on EBBJT were described.

Brassinosteroid and gibberellin promote many similar developmental responses in plants; however, their relationship remains unclear. Here we show that BR and GA act interdependently through a direct interaction between the BR-activated BZR1 and GA-inactivated DELLA transcription regulators. GA promotion of cell elongation required BR signalling, whereas BR or active BZR1 suppressed the GA-deficient dwarf phenotype. DELLAs directly interacted with BZR1 and inhibited BZR1-DNA binding both in vitro and in vivo. Genome-wide analysis defined a BZR1-dependent GA-regulated transcriptome, which is enriched with light-regulated genes and genes involved in cell wall synthesis and photosynthesis/chloroplast function. GA promotion of hypocotyl elongation requires both BZR1 and the phytochrome-interacting factors (PIFs), as well as their common downstream targets encoding the PRE-family helix-loop-helix factors. The results demonstrate that GA releases DELLA-mediated inhibition of BZR1, and that the DELLA-BZR1-PIF4 interaction defines a core transcription module that mediates coordinated growth regulation by GA, BR and light signals.

This study developed a multi-ions sensing system that includes pH, potassium, sodium, and chloride ion sensors with a wireless home-care system. The pH sensor was based on a tin oxide (SnO )/indium tin oxide (ITO) glass, and the potassium, sodium, and chloride ion sensors were based on the pH sensor with sensing membrane. The tin oxide (SnO) sensing membrane was deposited on indium tin oxide (ITO) substrate using a sputtering system. The sensing membranes of the ion sensors were prepared by mixing poly (vinyl chloride) (PVC), bis (2-ethylhexyl) sebacate (DOS), ionophores, and additives. According to the experimental results, sensitivities of the sensors all were over the value 51 mV/decade. The linear range of pH sensor was between pH2 and pH12, the linear ranges of potassium, sodium, and chloride sensors all were over from 1 mM to 1 M. Therefore, the multi-ions sensing system is suitable for monitoring of blood electrolytes. The correlations of the multi-ion sensors under different test solutions also were discussed. Moreover, this study also investigated sensors module, portable module, Bluetooth module, personal computer (PC) terminal, and portable unit of the wireless home-care system. A graphical measurement interface for data recorded and measurement results displayed was designed by National Instrument Lab-VIEW software. According to the experimental results, the measurement data by the wireless home-care system are near the real values. The wireless home-care system could successfully monitor and transmitted the sensing signals.

Homocysteine is a risk factor for coronary heart disease (CHD). This study aimed to develop a novel, simple and reliable homocysteine biosensor array (HBA) for precise determination of homocysteine. A low-cost and tiny amperometric HBA was fabricated with a D-amino acid oxidase immobilized on screen-printed carbon electrodes, with silver–silver chloride (Ag/AgCl) as reference electrode. The effects of the number of working electrodes (1, 2, 4 and 8) of the HBA, and the life-span on the response of the HBA were investigated. The HBA on the detection of homocysteine at +300 mV (versus Ag/AgCl) showed an excellent linear response range (6.4–100 μM) and fast response time (

Chih-Kuei Lee1, Congo Tak-Shing Ching2–4, Tai-Ping Sun2,3, Chun-Lang Tsai2, Wei Huang5, Hsin-Hung Huang6, Jen-Fu Kuo7, Li-Hang Lai6, Mei-Ya Chien8, Hsin-Hui Tseng9, Hui-Tzu Pan10, Shiow-Yuan Huang4, Hsiu-Li Shieh3, Wei-Hao Liu2, Chia-Ming Liu2, Hsin-Wei Huang21Hopkins Health Management Center, Puli Christian Hospital, Nantou, Taiwan, Republic of China; 2Graduate Institute of Biomedicine and Biomedical Technology, National Chi Nan University, Nantou, Taiwan, Republic of China; 3Department of Electrical Engineering, National Chi Nan University, Nantou, Taiwan, Republic of China; 4Department of Photonics and Communication Engineering, Asia University, Taichung, Taiwan, Republic of China; 5Division of Immunology and Rheumatology, Puli Christian Hospital, Nantou, Taiwan, Republic of China; 6Family Medical Department, Puli Christian Hospital, Nantou, Taiwan, Republic of China; 7Division of Endocrinology and Metabolism, Puli Christian Hospital, Nantou, Taiwan, Republic of China; 8Nutrition Department, Puli Christian Hospital, Nantou, Taiwan, Republic of China; 9Aboriginal Health Care, Puli Christian Hospital, Nantou, Taiwan, Republic of China; 10Department of Medical Research and Education, Puli Christian Hospital, Nantou, Taiwan, Republic of ChinaAbstract: The aim of this study was to find out the optimum combination of electroporation (EP) and reverse iontophoresis (RI) on noninvasive and transdermal determination of blood uric acid level in humans. EP is the use of high-voltage electric pulse to create nano-channels on the stratum corneum, temporarily and reversibly. RI is the use of small current to facilitate both charged and uncharged molecule transportation across the skin. It is believed that the combination of these two techniques has additional benefits on the molecules’ extraction across the human skin. In vitro studies using porcine skin and diffusion cell have indicated that the optimum mode for transdermal uric acid extraction is the combination of RI with symmetrical biphasic direct current (current density = 0.3 mA/cm2; phase duration = 180 s) and EP with 10 pulses per second (voltage = 100 V/cm2; pulse width = 1 ms). This optimum mode was applied to six human subjects. Uric acid was successfully extracted through the subjects’ skin into the collection solution. A good correlation (r2 = 0.88) between the subject’s blood uric acid level and uric acid concentrations in collection solutions was observed. The results suggest that it may be possible to noninvasively and transdermally determine blood uric acid levels.Keywords: Reverse iontophoresis, electroporation, uric acid, monitoring, noninvasive, transdermal

The diterpenoid hormone GA controls diverse developmental processes throughout the life cycle of a plant. Physiological and genetic studies show that active GA promotes seed germination and vegetative growth. In some species, GA also induces flowering and regulates flower, fruit, and seed development. This article highlights recent advances in our understanding of the molecular mechanisms of GA metabolism, transport, perception, and signaling, and the regulatory circuit between the GA pathway and other pathways to control plant growth and development in response to internal and external cues.

A potentiometric glucose biosensor based on a SnO2/ITO/PET substrate is presented in this study. The sensing membrane of SnO2 is coated on ITO/PET substrate by utilized radio frequency (RF)-sputtering method of semiconductor fabrication. The potentiometric glucose biosensor is established on an FET-type pH sensor. Therein, the glucose oxidase (GOD) and chitosan/multi-wall carbon nano-tubes (chitosan/MWCNTs) are immobilized by 3-glycidoxypropyl trimethoxysilane (3-GPTS). Finally, the drift characteristic and calibration curve of the potentiometric pH sensor and potentiometric glucose biosensor is discussed in the following article. We find the nonideal effect of device reduced significantly, due to the coating of SnO2 thin film.

A double potassium and sodium ions sensor based on separated extended gate field effect transistor (SEGFET) and a new entrapment method are proposed in this study. Having high sensitivity, reproducibility, and a simple manufacturing process, the sensors are quickly able to supply information and detect human blood within an abnormal range. The sensing membranes were fabricated using a Poly(vinyl chloride) carboxylated (PVC-COOH) matrix; sodium ionophore (B12C4) or potassium ionophore (valinomycin). The sensitivity of ion-selective biosensors is 42.55 mV/decade for Na+ between 1 M and 10-7 M, 42.75 mV/decade for K+ between 1 M and 10-6 M.

This work investigates a disposable creatinine potentiometric biosensor based on a pH-sensitive electrode and an ammonium ion-selective electrode. An enzyme, creatinine iminohydrolase (CIH) was immobilized directly onto the surface of the electrodes by the entrapment method. According to the experimental results, the creatinine biosensors based on the pH-sensitive electrode and ammonium ion-selective electrode show a rapid response time (t95 < 30 s) and a linear dynamic response range for creatinine determination between 40 muM and 140 muM. Furthermore, the ammonium ion-selective electrode-based biosensors exhibited good operational stability (over 14 times) and storage stability (over 40 days). By discussing the reproducibility and pH effects of the creatinine biosensors, features of creatinine biosensors based on ammonium ion-selective electrodes are described. Moreover, development of a low-cost, solid-state, disposable potentiometric creatinine biosensor based on pH-sensitive electrodes and ammonium ion-selective electrodes is discussed.

This work presents a differential solid-state urea biosensor based on an ion-selective membrane. The solid-state urea biosensor comprises three parts—a tin oxide (SnO 2 ) pH electrode, a nonactin-based ammonium ion-selective electrode (ISE) and an ammonium ion-selective membrane-based urea electrode. The enzyme was immobilized by the entrapment method onto an ion-selective membrane. For simplicity of fabrication, a SnO 2 /indium tin oxide (ITO) glass device was adopted as a basic substrate. Solid-state urea biosensors based on ammonium ion-selective membrane respond rapidly, stably and linearly in the range of urea concentrations between 0.013 mM and 10 mM. Additionally, the voltage response, selectivity, reproducibility and stability are considered. Experimental results indicate that the effect of the interference ions of a solid-state urea biosensor can be improved using the proposed differential urea sensing structure. Additionally, the biosensors exhibit good operational and storage stability.

The DELLA family of transcription regulators functions as master growth repressors in plants by inhibiting phytohormone gibberellin (GA) signaling in response to developmental and environmental cues. DELLAs also play a central role in mediating cross-talk between GA and other signaling pathways via antagonistic direct interactions with key transcription factors. However, how these crucial protein–protein interactions can be dynamically regulated during plant development remains unclear. Here, we show that DELLAs are modified by the O-linked N-acetylglucosamine (O-GlcNAc) transferase (OGT) SECRET AGENT (SEC) in Arabidopsis. O-GlcNAcylation of the DELLA protein REPRESSOR OF ga1-3 (RGA) inhibits RGA binding to four of its interactors—PHYTOCHROME-INTERACTING FACTOR3 (PIF3), PIF4, JASMONATE-ZIM DOMAIN1, and BRASSINAZOLE-RESISTANT1 (BZR1)—that are key regulators in light, jasmonate, and brassinosteroid signaling pathways, respectively. Consistent with this, the sec-null mutant displayed reduced responses to GA and brassinosteroid and showed decreased expression of several common target genes of DELLAs, BZR1, and PIFs. Our results reveal a direct role of OGT in repressing DELLA activity and indicate that O-GlcNAcylation of DELLAs provides a fine-tuning mechanism in coordinating multiple signaling activities during plant development.

Previous work showed that PHYTOCHROME-INTERACTING FACTOR3-LIKE5 (PIL5), a light-labile basic helix-loop-helix protein, inhibits seed germination by repressing GIBBERELLIN 3β-HYDROXYLASE1 (GA3ox1) and GA3ox2 and activating a gibberellic acid (GA) catabolic gene (GA2ox2). However, we show persistent light-dependent and PIL5-inhibited germination behavior in the absence of both de novo GA biosynthesis and deactivation by GA2ox2, suggesting that PIL5 regulates not only GA metabolism but also GA responsiveness. PIL5 increases the expression of two GA repressor (DELLA) genes, GA-INSENSITIVE (GAI) and REPRESSOR OF GA1-3 (RGA/RGA1), in darkness. The hypersensitivity of gai-t6 rga-28 to red light and the suppression of germination defects of a rga-28 PIL5 overexpression line show the significant role of this transcriptional regulation in seed germination. PIL5 also increases abscisic acid (ABA) levels by activating ABA biosynthetic genes and repressing an ABA catabolic gene. PIL5 binds directly to GAI and RGA promoters but not to GA and ABA metabolic gene promoters. Together, our results show that light signals perceived by phytochromes cause a reduction in the PIL5 protein level, which in turn regulates the transcription of two DELLA genes directly and that of GA and ABA metabolic genes indirectly.

Regular monitoring of blood α-fetoprotein (AFP) and/or carcino-embryonic antigen (CEA) levels is important for the routine screening of liver cancer. However, AFP and CEA have a much lower specificity than des-γ-carboxyprothrombin (DCP) to detect liver cancer. Therefore, the study reported here was designed, to develop a screen-printed DCP immunosensor incorporating zinc oxide nanoparticles, for accurate determination of DCP. The designed immunosensor shows low detection limits for the detection of DCP: 0.440 ng/mL (based on impedance measurement), 0.081 ng/mL (based on real part of impedance measurement) and 0.078 ng/mL (based on imaginary part of impedance measurement), within the range of 3.125 ng/mL to 2000 ng/mL. In addition, there was little interference to DCP determination by molecules such as Na⁺, K⁺, Ca(2+), Cl(-), glucose, urea, and uric acid. It is therefore concluded that the DCP immunosensor developed and reported here is simple, inexpensive and effective, and shows promise in the rapid screening of early-stage liver cancer at home with a point-of-care approach.

Regular check of blood creatinine level is very important as it is a measurement of renal function. Therefore, the objective of this study is to develop a simple and reliable creatinine biosensor based on admittance measurement for precise determination of creatinine. The creatinine biosensor was fabricated with creatinine deiminase immobilized on screen-printed carbon electrodes. Admittance measurement at a specific frequency ranges (22.80 - 84.71 Hz) showed that the biosensor has an excellent linear (r2 > 0.95) response range (50 - 250 uM), which covers the normal physiological and pathological ranges of blood creatinine levels. Intraclass correlation coefficient (ICC) showed that the biosensor has excellent reliability and validity (ICC = 0.98). In conclusion, a simple and reliable creatinine biosensor was developed and it is capable of precisely determining blood creatinine levels in both the normal physiological and pathological ranges.

International audience; In a wide range of plant species, seed germination is regulated antagonistically by two plant hormones, abscisic acid (ABA) and gibberellin (GA). In the present study, we have revealed that ABA metabolism (both biosynthesis and inactivation) was phytochrome-regulated in an opposite fashion to GA metabolism during photoreversible seed germination in Arabidopsis. Endogenous ABA levels were decreased by irradiation with a red (R) light pulse in dark-imbibed seeds pre-treated with a far-red (FR) light pulse, and the reduction in ABA levels in response to R light was inhibited in a phytochrome B (PHYB)-deficient mutant. Expression of an ABA biosynthesis gene, AtNCED6, and the inactivation gene, CYP707A2, was regulated in a photoreversible manner, suggesting a key role for the genes in PHYB-mediated regulation of ABA metabolism. Abscisic acid-deficient mutants such as nced6-1, aba2-2 and aao3-4 exhibited an enhanced ability to germinate relative to wild type when imbibed in the dark after irradiation with an FR light pulse. In addition, the ability to synthesize GA was improved in the aba2-2 mutant compared with wild type during dark-imbibition after an FR light pulse. Activation of GA biosynthesis in the aba2-2 mutant was also observed during seed development. These data indicate that ABA is involved in the suppression of GA biosynthesis in both imbibed and developing seeds. Spatial expression patterns of the AtABA2 and AAO3 genes, responsible for last two steps of ABA biosynthesis, were distinct from that of the GA biosynthesis gene, AtGA3ox2, in both imbibed and developing seeds, suggesting that biosynthesis of ABA and GA in seeds occurs in different cell types.

In this paper, uricase, catalase, and electron mediator were coimmobilized on the surface of the tin oxide (SnO/sub 2/)/indium tin oxide (ITO) glass, to develop a disposable potentiometric uric acid biosensor. The SnO/sub 2/ / ITO glass was employed as a pH sensor, fabricated by sputtering SnO/sub 2/ thin films on the ITO glass. 3-Glycidyloxypropyltrimethoxysilane (GPTS) was utilized to immobilize uricase, catalase and the electron mediator (ferrocenecarboxylic acid, FcA) on the sensing window. The experimental results reveal that the optimal weight ratio of uricase, FcA to catalase (CAT) is 4:1:2. The sensor responds linearly between 2 mg/dl and 7 mg/dl at pH 7.5, in 20 mM of test solution, with a correlation coefficient of 0.99213. Accordingly, no significant interference was observed when interfering substances, glucose, urea and ascorbic acid, were added to the uric acid solution. Moreover, the recorded voltage was relatively constant during the first 28 days of measurement. Consequently, a potentiometric uric acid biosensor was realized with the advantages of low cost and simple fabrication.

A potentiometric urea biosensor is prepared by the immobilization of urease directly onto the surface of a solid-state ammonium ion-selective electrode. The enzyme is immobilized by entrapment method onto a nonactin membrane that incorporated carboxylated polyvinylchloride. The same method of immobilization method is adopted to compare the characteristics of urea biosensors based on ammonium ion-selective electrodes with those based on pH-sensitive electrodes, using the same tin-oxide (SnO/sub 2/)/indium tin-oxide glass substrate. Urea biosensors based on ammonium ion-selective electrodes respond quickly and stably to changes in urea concentrations between 0.026 and 10 mM. The slope in the linear range is around 55.56/spl plusmn/3.15 mV/decade and the detection limit is around 5 /spl mu/M. The effect of urea biosensors with different pH values is considered, and the characteristics of urea biosensors based on ammonium ion-selective electrodes are described. Additionally, the experimental results from the determination of the urea using biosensors based on pH-sensitive electrodes and ammonium ion-selective electrodes are compared and discussed.

In this paper, the solid-state urea biosensor was successfully fabricated based on the differential method, which contains three parts: the SnO/sub 2//ITO glass electrode used as the pseudoreference electrode; the SnO/sub 2//ITO glass electrode used as the contrast electrode; and the urease/SnO/sub 2//ITO glass electrode used as the enzyme electrode. Correspondingly, this solid-state urea biosensor was fabricated based on the SnO/sub 2//ITO glass electrode, whose simple fabrication process reduces the cost of fabricating the solid-state biosensor. Additionally, as revealed in the experimental results, the solid-state urea biosensor has good sensing characteristics between 5 and 80 mg/dl. After fabricating a successful solid-state urea biosensor, an array sensing system was designed to enhance the precision of the solid-state urea biosensor, which comprises four parts: the biosensor system, the input buffer circuit, the differential circuit, and the weighted sum circuit. As indicated in the experimental results of the array sensing system, the sensing characteristic of the array sensing system is similar to the mean sensing characteristic from four solid-state biosensors. Therefore, the sensing signal of the solid-state urea biosensor can be averaged using the array sensing system. In summary, this study successfully investigated a solid-state urea biosensor and designed an array sensing system to increase the precision of solid-state urea biosensors.

Bioactive gibberellins (GAs) are plant hormones that control growth and development throughout the life cycle of the plant. Isolation and characterization of mutants that are impaired in GA biosynthesis have been crucial in both understanding the role of GAs in regulating plant development and elucidating the GA biosynthetic pathway (Davies, 1995; Hedden and Phillips, 2000). The broad spectrum of developmental processes controlled by GAs is clearly illustrated by the phenotypes of GA biosynthesis mutants. In general, these GA-deficient mutants exhibit a common phenotype: a dark-green dwarf plant that is defective in leaf expansion and stem elongation (Fig. 1). In many species, GA-deficient mutants also display defects during seed germination, altered floral initiation time, and are impaired in development of flower, fruit, and seed. In recent years our understanding of GA metabolism has advanced rapidly with the cloning of

In this study, extended-gate field effect transistor (EGFET) was applied to fabricate disposable urea biosensor. And the 1.5 V low-voltage instrument amplifier was adopted to realize the portable urea biosensor. However, the difference between extended-gate field effect transistor and traditional ion-selective field effect transistor is the position of the sensitive membrane. The extended-gate field effect transistor was separated into two parts, which are the sensitive membrane and MOSFET. Hence, the MOSFET device can be designed to be a part of the readout circuit and the sensitive membrane was only put in the solution. Therefore, the configuration of the extended-gate field effect transistor can reduce the influence of the temperature, light and the erosion by the solutions. Besides, the configuration can reduce the cost substantially. The configuration of the extended-gate field effect transistor will raise the competitiveness to develop the disposable biosensor. The content of the urea in blood is one of the indexes to diagnose the renal efficiency. Then, the portable urea biosensor is the important expandable aspect. In this study, the gels, which are the poly vinyl alcohol with pendent styrylpyridinium groups, were used to immobilize the urease. The detection of the urea is based on the variation of pH value. Then, the dynamic range of the urea biosensor is from 0.31 to 120 mg/dl at the 5 mM phosphate buffer solution and the response time is about 2 min.

In this study, the pH-based urea biosensor has been used in the flow injection analysis (FIA) system. A type of potentiometric sensing system for urea was constructed, which based on the buffer concentration to the response of urea. However, the extended-gate field effect transistor is applied to fabricate the pH-based urea biosensor and the photo-curable gels (PVA-SbQ) is used to immobilize the urease. In aspect of the flow injection analysis system, the samples were injected by the pumps and passed through from the injection valve, which could be single port or multi-ports. And then, the solvent and the samples were mixed. After that, the solution of mixer flows to micro flow through cell. Through the flow system, the output signal is observed by the detection. The flow injection analysis system has some advantages, such as reaction faster, more reproducible, long lifetime and less work-consuming. Hence, the application of the flow injection analysis system can improve the analytical feature of the urea biosensor.

In this paper, we use the extended gate field effect transistor (EGFET) and the coated wire electrode (CWE) to design a differential pH-sensing device. The SnO/sub 2//ITO glass structure is the EGFET used as the pH sensor because of its excellent pH sensitivity of about 57.10 mV/pH. The contrast pH sensor is the polypyrrole/SnO/sub 2//ITO glass structure CWE, which has the lower pH sensitivity of about 27.81 mV/pH, and we use the third SnO/sub 2//ITO glass structure as the reference electrode to serve the base potential of the electrolyte solution. The pH sensitivity of this differential pH-sensing device is about 30.14 mV/pH and it is linear. Hence, this device is a good pH sensor. By using this technology, the differential pH-sensing device has a lot of advantages, such as simple fabrication, solid-state electrodes, easy packaging, low cost, etc.

In this study, a glucose-sensitive enzyme field-effect transistor (ENFET) coimmobilized with glucose oxidase (GOD) and manganese dioxide (MnO 2 ) have been investigated. The biomembrane of the ENFET was immobilized on the amorphous tin oxide/indium tin oxide glass structure extended sensitive gate, which used as a disposable transducer of a glucose biosensor. MnO 2 was used as a catalyst which can catalyze the hydrogen peroxide and produced H 2 O and O 2 . Coimmobilizaion of glucose oxidase and manganese dioxide was found to be useful for extending the dynamic measured range of glucose concentration to 360 mg/dl (eq. 20 mM). The result shows that the dynamic range of the output signal is strongly dependent on pH value of measuring environments, and the measurement in the alkali buffer solutions shows a higher response and wider dynamic range. Additionally, the different immobilized layers of MnO 2 have been studied. The MnO 2 , which be immobilized in outer cross-linking layer of bovine serum albumin, shows better results than immobilized in GOD layer or gultaraldehyde covalent layer.

In this study, the indium tin oxide (ITO) was used as a sensitive film for H + ion sensitive field effect transistor (ISFET). The sensitive characteristics of ITO glass structure for separative extended gate ion sensitive field effect transistors (EGFET) were studied. ITO thin film is used for the first time as a H + ion sensitive film which has a linear pH sensitivity of Nerstern response, about 58 mV/pH, between pH 2 and pH 12.

Silicon nitride (Si/sub 3/N/sub 4/) sensing gate pH-ion-selective field effect transistors (ISFETs) were treated by 2.54-GHz microwave O/sub 2/ plasma, the results show the ISFET sensitivity has an advantage up to 24% increment after the plasma treatment. Electron spectroscopy for chemical analysis (ESCA) is used to make sure that the plasma treatment is not just a native oxide cleaning procedure. The samples, which were immobilized with glutaraldehyde used as a bifunctional reagent and 3-aminopropy-Itricthoxysilane used as an adhesion promoter were studied. The binding force between the glucose oxidase and glutaraldehyde immobilized samples, and the element concentrations of nitrogen in 3-aminspropytriethoxysilane immobilized samples are higher which were treated by plasma.

Recent studies using biochemical and genetic approaches have identified a number of components, including several negative regulators, of the gibberellin (GA) signal transduction pathway in higher plants. The basal state of GA signaling is likely to be repressive, and the GA signal seems to activate the pathway by de-repression to allow GA-stimulated growth and development.

Ion-sensitive field effect transistor (ISFET) is a device composed of a conventional ion-sensitive electrode and MOSFET device, applied to the measurement of ion content in a solution. Extended gate field effect transistor (EGFET) is another structure to isolate FET from chemical environment. In this study, the ISFET was separated into two parts. Tin dioxide (SnO2), obtained by sputtering, is used as a pH-sensitive membrane for electrode, which is connected with a commercial MOSFET device in CD4007UB or LF356N. The experimental data show that this structure has a linear pH response of about 56–58 mV/pH in a concentration range between pH 2 and 12. In addition, it is easier to fabricate and package the sensitive membrane structure and the measurement is simple for the application of disposable biosensor.

701-708. The two-step cyclization reaction of ent-kaurene synthesis from geranylgeranyl diphosphate is the first committed step in the biosynthetic pathway of the plant hor- mone gibberellin. Recent molecular cloning and characterization of the genes encod- ing the two corresponding enzymes, copalyl diphosphate synthase (CPS) and ent-kau- rene synthase (KS), have demonstrated that ent-kaurene synthesis is localized in the plastids and is highly regulated in specific tissues and cell types during plant develop- ment. In addition to occurring in actively growing tissues, ent-kaurene synthesis also takes place in fully expanded leaves. Therefore mature leaves may produce gibberel- lin intermediates or bioactive gibberellins for transport to responsive tissues. DNA se- quence analyses have revealed a conserved aspartate-rich motif, D(W)DDTA among CPS and other protonation-initiated terpene cyclases, while KS contains a highly con- served DDXXD motif which was proposed to function as a divalent metal ion-diphos- phate complex binding site in ionization-initiated terpene cyclases and prenyltrans- ferases. Key words - Cell-type specific regulation, ent-kaurene synthesis, plastid localization, terpene cyclases. 2-p. Sun (corresponding authol; e-mail tps@acpub.duke.edu), Developmental, Cell and Molecular Biology Group, Dept of Botany, Box

Ga/sub 0.51/In/sub 0.49/P/In/sub 0.15/Ga/sub 0.85/As/GaAs pseudomorphic doped-channel FETs exhibiting excellent DC and microwave characteristics were successfully fabricated. A high peak transconductance of 350 mS/mm, a high gate-drain breakdown voltage of 31 V and a high maximum current density (575 mA/mm) were achieved. These results demonstrate that high transconductance and high breakdown voltage could be attained by using In/sub 0.15/Ga/sub 0.85/As and Ga/sub 0.51/In/sub 0.49/P as the channel and insulator materials, respectively. We also measured a high-current gain cut-off frequency f/sub t/ of 23.3 GHz and a high maximum oscillation frequency f/sub max/ of 50.8 GHz for a 1-/spl mu/m gate length device at 300 K. RF values where higher than those of other works of InGaAs channel pseudomorphic doped-channel FETs (DCFETs), high electron mobility transistors (HEMTs), and heterostructure FETs (HFETs) with the same gate length and were mainly attributed to higher transconductance due to higher mobility, while the DC values were comparable with the other works. The above results suggested that Ga/sub 0.51/In/sub 0.49/P/In/sub 0.15/Ga/sub 0.85/As/GaAs doped channel FET's were were very suitable for microwave high power device application.

The purpose of this study was to develop novel nanoscale biosensors using titania nanotubes (TNTs) made by anodization. Titania nanotubes were produced on pure titanium sheets by anodization at room temperature. In this research, the electrolyte composition ethylene glycol 250 mL/NH4F 1.5 g/DI water 20 mL was found to produce the best titania nanotubes array films for application in amperometric biosensors. The amperometric results exhibit an excellent linearity for uric acid (UA) concentrations in the range between 2 and 14 mg/dL, with 23.3 (µA·cm−2)·(mg/dL)−1 UA sensitivity, and a correlation coefficient of 0.993. The glucose biosensor presented a good linear relationship in the lower glucose concentration range between 50 and 125 mg/dL, and the corresponding sensitivity was approximately 249.6 (µA·cm−2)·(100 mg/dL)−1 glucose, with a correlation coefficient of 0.973.

Doxorubicin (DOX) is an extensively used anthracycline that has proven to be effective against a variety of human malignant tumors, such as ovarian or breast cancer. While DOX was administered into cultured cancer cell targets (such as CHO-K1) in either free drug form or in drug carrier-associated form (i.e., DOX encapsulated in the drug delivery carrier), various action of mechanisms for DOX were initiated, among which, it has been long believed that DOX enters the nucleus, interacts with DNA in numerous ways, and finally halts cell proliferation. Aside from its therapeutic effect, regrettably DOX treatment may be accompanied by the occurrence of cardiac and liver toxicity and drug resistance that are attributed from cellular processes involving the parent drug or its metabolites. Liposomal formulation of DOX, known to be capable of attenuating direct uptake of reticuloendothelial system (RES) and prolonging the circulation time in blood, demonstrated reduced toxic side-effects. We herein report the development of a modified MEKC-LIF (Micellar electrokinetic chromatography-Laser-induced fluorescence) method suitable for analyzing DOX in biological samples. The MEKC migration buffer, consisting of 10 mM borate, 100 mM sodium dodecyl sulfate (SDS) (pH 9.3), was found to provide an efficient and stable electrophoretic separation and analysis for DOX. Responses were linear in the range of 11.3-725 ng/mL; the limit of quantitation (LOQ) was found to be 43.1 ng/mL (S/N=10) (equivalent to 74.3 nM) and limit of detection (LOD) was calculated as 6.36 ng/mL (S/N=3) (equivalent to 11.0 nM). This approach was subsequently employed to compare the intracellular accumulation in three subcellular fractions of DOX-treated CHO-K1 cells. These fractions form a pellet at1400 g, 1400-14000 g, and14000 g and are enriched in nuclei, organelles (mitochondria and lysosomes), and cytosole components, respectively, resulting from treatment of CHO-K1 cells with 25 μM (equivalent to 14.5 μg/mL) of two DOX formats (in free drug form or liposomal form synthesized in current study) for different periods of time. Our results indicated that the most abundant DOX was found in the nuclear-enriched fraction of cells treated for 12 h and 6 h with free and liposomal DOX, respectively, providing direct evidence to confirm the enhanced efficiency of liposomal carriers in delivering DOX into the nucleus. The observations presented herein suggest that subcellular fractionation followed by liquid-liquid extraction and MEKC-LIF could be a powerful diagnostic tool for monitoring intracellular DOX distribution, which is highly relevant to cytotoxicity studies of anthracycline-type anticancer drugs.

Plants must effectively defend against biotic and abiotic stresses to survive in nature. However, this defense is costly and is often accompanied by significant growth inhibition. How plants coordinate the fluctuating growth-defense dynamics is not well understood and remains a fundamental question. Jasmonate (JA) and gibberellic acid (GA) are important plant hormones that mediate defense and growth, respectively. Binding of bioactive JA or GA ligands to cognate receptors leads to proteasome-dependent degradation of specific transcriptional repressors (the JAZ or DELLA family of proteins), which, at the resting state, represses cognate transcription factors involved in defense (e.g., MYCs) or growth [e.g. phytochrome interacting factors (PIFs)]. In this study, we found that the coi1 JA receptor mutants of rice (a domesticated monocot crop) and Arabidopsis (a model dicot plant) both exhibit hallmark phenotypes of GA-hypersensitive mutants. JA delays GA-mediated DELLA protein degradation, and the della mutant is less sensitive to JA for growth inhibition. Overexpression of a selected group of JAZ repressors in Arabidopsis plants partially phenocopies GA-associated phenotypes of the coi1 mutant, and JAZ9 inhibits RGA (a DELLA protein) interaction with transcription factor PIF3. Importantly, the pif quadruple ( pifq ) mutant no longer responds to JA-induced growth inhibition, and overexpression of PIF3 could partially overcome JA-induced growth inhibition. Thus, a molecular cascade involving the COI1–JAZ–DELLA–PIF signaling module, by which angiosperm plants prioritize JA-mediated defense over growth, has been elucidated.

Bioactive gibberellins (GAs) are diterpene phytohormones that modulate growth and development throughout the whole life cycle of the plant. Arabidopsis genes encoding most GA biosynthesis and catabolism enzymes, as well as GA receptors (GIBBERELLIN INSENSITIVE DWARF1, GID1) and early GA signaling components have been identified. Expression studies on the GA biosynthesis genes are beginning to reveal the potential sites of GA biosynthesis during plant development. Biochemical and genetic analyses demonstrate that GA de-represses its signaling pathway by binding to GID1s, which induce degradation of GA signaling repressors (DELLAs) via an ubiquitin-proteasome pathway. To modulate plant growth and development, the GA pathway is also regulated by endogenous signals (other hormones) and environmental cues (such as light, temperature and salt stress). In many cases, these internal and external cues directly affect GA metabolism and bioactive GA levels, and indirectly alter DELLA accumulation and GA responses. Importantly, direct negative interaction between DELLA and PIF3 and PIF4 (2 phytochrome interacting transcription factors) appears to integrate the effects of light and GA on hypocotyl elongation.

The average particle sizes of nanoscale (Ba 0.8 Sr 0.2 )(Ti 0.9 Zr 0.1 )O 3 ceramic powder (nano-BSTZ) was approximately 73nm. Polyvinylidene fluoride (PVDF)/nano-BSTZ composite films with various contents of the nano-BSTZ were screen-printed on indium tin oxide glass substrates. From the XRD patterns, PVDF was the semicrystalline type polymer. The content of the nano-BSTZ increased from 10 wt% to 50 wt%, the dielectric constants of the PVDF/nano-BSTZ films slightly decreased with increasing measured frequency. The specific capacitance values of the PVDF/nano-BSTZ composite films mixing with 50 wt% nano-BSTZ was 11.6 nF/cm2 (measured at 1 kHz). Those results suggested that the PVDF/nano-BSTZ composite films were a good candidate to develop thinner embedded capacitor devices with higher capacitance value.

In this study, an extended base bipolar junction transistor (EBBJT) was proposed to fabricate disposable urea biosensor. The detection of the urea is based on the variation of pH value. The gels, fabricated by the poly vinyl alcohol with pendent styrylpyridinium groups, were used to immobilize the urease. The SnO 2 /ITO glass, fabricated by sputtering SnO 2 on the conductive ITO glass, was used as a pH-sensitive membrane for electrode, which is connected with a commercial bipolar junction transistor device. This readout circuit, fabricated in a 0.35-um CMOS 2P4M process, operated at 3.3V supply voltage. The circuit occupied an area of 1.0 mm × 0.9 mm. The dynamic range of the urea biosensor is from 1.4 to 64 mg/dl at the 10 mM phosphate buffer solution and the sensitivity of this range is about 65.8 mV/pUrea.

The effect of gibberellin (GA) on promoting stem growth was first discovered in 1930s by studies of the Bakanae(foolish seedling) disease in rice (57). Gibberella fujikuroi, a pathogenic fungus, produces gibberellic acid (GA3) that causes the infected rice plants to grow so tall that they fall over. Later studies of dwarf mutants and analysis of their GA contents revealed that bioactive GAs are endogenous hormones that regulate the natural developmental processes including stem growth in plants. An increase in both cell elongation and cell division occurs during stem growth. GA induces transcription of genes involved in these processes. For example, expression of some of the genes encoding xyloglucan endotransglycosylases (XETs1) and expansins are upregulated by GA in elongating internodes in rice and in Arabidopsis (7, 62, 66). XET is thought to increase the plasticity of the cell wall because this enzyme is involved in xyloglucan reorganization through cleaving and re-ligating xyloglucan polymers in the cell wall. Expansins are also extracellular proteins that cause plant cell wall loosening, probably by disrupting the polysaccharide adhesion. Transcripts of the genes encoding for cyclin-dependent protein kinases are also elevated in intercalary meristem in rice after GA treatment (12).

In this work, the 30 stacked InAs/GaAs quantum dot infrared photodetector (QDIP) structure was grown by solid-source molecular beam epitaxy technique and demonstrated with dual-band mid- (2.7~5.6μm) and long- (7.5~13.5μm) wavelength normal-incident detections without grating and passivated process for 256×256 FPA. The 256 ×256 QDIP FPA hybridized with snapshot-mode ROIC was mounted in a 68 pin leadless ceramic chip carrier which was put in the testing dewar with IR optical cold spectral filters of the 2.9~5.5μm and 6.5~14.5 μm for the dual-band IR detections, respectively. The testing scheme for thermal imaging uniformity of the InAs/GaAs QDIP focal plane array (FPA) has been proposed and calibrated using a plane-typed blackbody source of a high temperature of 373±1K and lower ambient temperature for the two-point temperature correction. The averaged of specific detectivity (D*) and operability of the QDIP FPA have reached 1.5×10 10 cm-Hz 1/2 /W and 99% at 80K, respectively. The dominant noise equivalent temperature differences (NEDT) of typical figure of merit for QDIP thermal imaging module operated under the temperature of 80K, device biases of -0.7 V and integration time of 32ms with infrared optics and two-point temperature correction (T L =R.T. and T H = 200 °C) are 1.065 K (mid-wavelength IR) and 131mK (long-wavelength IR), respectively. Meanwhile, it is worth to note that these are the first confirmation for dual-band detections of FPA from direct InAs quantum dots matrix embedded in GaAs heterostructure. In the future, the dual-band IR QDIP FPA will become one of the important candidates for hyper-spectral detection and thermal imaging fusion application.

This work presents a differential structure of solid-state creatinine array biosensor based on an ion-selective membrane. The creatinine enzyme is chemically immobilized by a physical immobilization method onto an ammonium ion-selective membrane. Moreover, the solid-state creatinine biosensors based on ammonium ion-selective membrane respond rapidly, stably and linearly in the range of creatinine concentrations between 15 muM and 140 muM. An array sensing system is designed to enhance the precision of the solid-state creatinine biosensor, which comprises four parts, the creatinine biosensors, the input buffer circuit, the differential circuit and the weighted sum circuit. As indicated in the experimental results of the array sensing structure, the sensing characteristic of the array sensing structure is similar to the mean sensing characteristic from four solid-state creatinine biosensors.

A novel structure Ga/sub 0.51/In/sub 0.49/P/GaAs MISFET with an undoped Ga/sub 0.51/In/sub 0.49/P layer serving as the airbridge between active region and gate pad was first designed and fabricated. Wide and flat characteristics of g/sub m/ and f/sub max/ versus drain current or gate voltage were achieved. The device also showed a very high maximum current density (610 mA/mm) and a very high gate-to-drain breakdown voltage (25 V). Parasitic capacitances and leakage currents were minimized by the airbridge gate structure and thus high f/sub T/ of 22 GHz and high f/sub max/ of 40 GHz for 1 /spl mu/m gate length devices were attained. To our knowledge, both were the best reported values for 1 /spl mu/m gate GaAs channel FET's. >

The Au/Cr/a-SiN/sub x/:H/(n)InAs/GaAs metal-insulator-semiconductor (MIS) capacitor was fabricated as a basic element of charge injection devices using plasma enhanced chemical vapour deposition. The electrical properties of the capacitor were analysed as a function of temperature using high frequency (1 MHz) capacitance-voltage measurements. It was demonstrated that the capacitor can still be biased into deep depletion at 180 K. When this capacitor is used as an integrated infrared detector in a charge injection device, it exhibits the capacity to detect infrared signals at a temperature of 180 K, higher than that of an InSb infrared detector (77 K), and the device can be cooled thermoelectrically.

The power of molecular genetics has dramatically advanced our understanding of all aspects of gibberellin (GA) signaling. Many genes encoding GA response pathway components have been identified using Arabidopsis and cereal mutants, and more elaborate genetic screens are producing additional mutants

Congo Tak-Shing Ching,1,2 Kok-Khun Yong,3 Yan-Dong Yao,4 Huan-Ting Shen,3 Shiu-Man Hsieh,5 Deng-Yun Jheng,1 Tai-Ping Sun,1,6 Hsiu-Li Shieh11Department of Electrical Engineering, National Chi Nan University, Nantou, 2Department of Photonics and Communication Engineering, Asia University, Taichung, 3Department of Internal Medicine, Puli Christian Hospital, Nantou, People’s Republic of China; 4Division of Science and Technology, Hong Kong Community College, Hong Kong; 5Department of Orthopedic Surgery, Puli Christian Hospital, 6Department of Electronic Engineering, Nan Kai University of Technology, Nantou, People’s Republic of ChinaAbstract: The aims of this study were to investigate the most effective combination of physical forces from laser, electroporation, and reverse iontophoresis for noninvasive transdermal extraction of uric acid, and to develop a highly sensitive uric acid biosensor (UAB) for quantifying the uric acid extracted. It is believed that the combination of these physical forces has additional benefits for extraction of molecules other than uric acid from human skin. A diffusion cell with porcine skin was used to investigate the most effective combination of these physical forces. UABs coated with ZnO2nanoparticles and constructed in an array configuration were developed in this study. The results showed that a combination of laser (0.7W), electroporation (100V/cm2), and reverse iontophoresis (0.5mA/cm2) was the most effective and significantly enhanced transdermal extraction of uric acid. A custom-designed UAB coated with ZnO2nanoparticles and constructed in a 1×3array configuration (UAB-1×3-ZnO2) demonstrated enough sensitivity (9.4µA/mM) for quantifying uric acid extracted by the combined physical forces of laser, electroporation, and RI. A good linear relationship (R2=0.894) was demonstrated to exist between the concentration of uric acid (0.2–0.8mM) inside the diffusion cell and the current response of the UAB-1×3-ZnO2. In conclusion, a new approach to noninvasive transdermal extraction and quantification of uric acid has been established.Keywords: laser, electroporation, reverse iontophoresis, noninvasive, uric acid, biosensor

Gibberellins (GAs) are hormones required for several aspects of plant development, including internode elongation and seed development in pea (Pisum sativum L.). The first committed step in the GA biosynthesis pathway is the conversion of geranylgeranyl diphosphate (GGDP) to ent-kaurene via copalyl diphosphate (CDP). These two reactions are catalyzed by the cyclases ent-kaurene synthase A (KSA) and ent-kaurene synthase B (KSB), respectively. Previous genetic and biochemical analysis of the GA-responsive ls-1 mutant of pea suggested that GA levels are reduced in a developmental- and organ-specific manner due to reduced GA biosynthesis. Analysis of cellfree enzyme preparations from WT and ls-1 embryos at contact point reveals that ls-1 reduces the activity of KSA but not KSB. To characterize the ls-1 mutation in more detail, a cDNA coding for a pea KSA was cloned and shown to be encoded by the LS locus. The ls-1 mutation results from an intronic G to A substitution that causes impaired RNA splicing. To determine the activity of the KSAs encoded by the LS and ls-1 alleles, a new in vitro assay for combined KSA and KSB activity has been developed using the KSB gene of pumpkin. Using recombinant WT KSA and KSB fusion proteins, GGDP is converted to ent-kaurene in vitro. Based on the sequence of RT-PCR products, three different truncated KSA proteins are predicted to exist in ls-1 plants. The most abundant mutant KSA protein does not possess detectable activity in vitro. Nevertheless, the ls-1 allele is not null and is able to encode at least a partially functional KSA since a more severe is allele has been identified. The ls-1 mutation has played a key role in identifying a role for GAs in pea seed development in the first few days after fertilization, but not in older seeds. KSA expression in seeds is developmentally regulated and parallels overall GA biosynthesis, suggesting that KSA expression may play an important role in the regulation of GA biosynthesis and seed development.

An all-solid-state chloride electrode based on a tin oxide (SnO2)/indium tin oxide (ITO) glass was developed in this study. The sensing membrane of the electrode was prepared by mixing poly(vinyl chloride) (PVC), bis(2-ethylhexyl) sebacate (DOS), [4,5-dimethy-l-3,6-bis(dodecyloxy)-1,2-phenylene] bis(mercury chloride) (ETH9033), and tridodecylmethyl ammonium chloride (TDDMACl). The mixed solution was mixed with tetrahydrofuran (THF), and then dropped on the sensing window of SnO2/ITO glass. According to the experimental results, the optimal weight ratio were PVC:DOS:ETH9033:TDDMACl=33:66:2:5. At this optimum weight ratio, the sensitivity was 54 mV/dec while the range of linear concentrations of NaCl solutions was between 10-4 and 1 M. The lower detection limit of the sensor reached 8×10-5 M and the response time was less than 1 s. The selectivity coefficient was consistent with the theory of Hofmeister lipophilicity. The lifetime was over 60 days and the repeatability was over 50 times. Moreover, the chloride ion sensor was successfully applied to detecting chloride ions in rinsing solutions for contact lenses, and the experimental results revealed that the correlation coefficient was 0.99.

This study developed a potentiometric pCO 2 sensor to measure dissolved carbon dioxide. The potentiometric pCO 2 sensor was based on a SnO 2 /carbon structure. The pCO 2 sensor based on the SnO 2 /carbon electrode was made by coating the surface of SnO 2 with a silicone rubber film doped with valinomycin and covered with a solid electrolyte membrane inside the gas-permeable membrane. Moreover, the solid electrolyte membrane was separated from a sample by a polysiloxane membrane, which is permeable to CO 2 . The CO 2 molecules diffused through the membrane into the solid electrolyte membrane, and a resulting pH change was detected by the SnO 2 pH-sensitive membrane. According to the experimental results, the sensitivity of the potentiometric pCO 2 sensor was about 26.1 mV/dec in the range of 0.5-30 mM dissolved CO 2 . The pCO 2 sensors based on the SnO 2 /carbon have an easy fabrication process. Moreover, the SnO 2 /carbon structure could be the substrate of a multisensor.

Tin oxide (SnO 2 ) thin films are sputtered onto a commercial carbon electrode to develop a SnO 2 electrode. A mediator (ferrocene-carboxylic acid) and an enzyme (glucose oxidase) are coimmobilized by polyvinylalcohol bearing styrylpyridinium groups on the surface of the carbon and SnO 2 electrodes, to fabricate carbon and SnO 2 amperometric glucose biosensors. Following electrode modification, the applied potential is reduced from 452 to 236 mV and the current response increases from 320 to 508 μA cm -2 as the carbon and SnO 2 amperometric glucose biosensors are immersed in 360 mg/dL glucose solution. The detection limit of the carbon amperometric glucose biosensor is 360 mg/dL under an applied potential of 452 mV. Furthermore, when the applied potential is set to 236 mV, the detection limit of the SnO 2 amperometric glucose biosensor reaches 600 mg/dL. No significant interference is observed when the applied potential is set at 236 mV. Furthermore, the glucose concentration determined by the glucose presence in the serum sample agrees closely with that in the buffer solution. The merits of reducing the applied potential and increasing current response enable a highly accurate SnO 2 amperometric glucose biosensor based on a low-cost substrate to be developed in this study.

An all-solid-state potassium electrode based on tin oxide (SnO 2 )lindium tin oxide (ITO) glass is developed in this paper. The sensing membrane of the electrode is prepared by mixing poly(vinyl chloride) (PVC), bis(2-ethylhexyl) sebacate (DOS), valino-mycin (VAL), and potassium tetrakis(p-chlorophenyl) borate (KTpClPB). The mixed solution is dissolved in tetrahydrofuran (THF). Then, it is dropped on the sensing window of SnO 2 /ITO glass. In addition, the Ag/AgCl wire, which is coated PVC membrane containing 3.5 M KCl powder, is used as a miniaturized reference electrode in this study. The optimum experiment of the potassium sensor is conducted by observing the characteristics of sensitivity and selectivity in different weight ratios. After the optimum experimental trials, the best weight ratio of the potassium sensor is PVC:DOS:VAL:KTpClPB = 33:66:4:2. In this optimum condition, the sensitivity is 56.4 mV/decade with linear concentration range between 1 X 10 -5 M and 1 M. The low detection limit of the sensor reaches to 8 × 10 -6 M, and response time is < 1 s. Moreover, the sensor is slight interfered by sodium, calcium, and magnesium ions. The pH variation does not affect its electromotive force in the range between pH 6 and pH 12. The sensor possesses reusable properties showing that it can be repeated, measuring 30 times.

The objective of this work is the study and characterization of anodized aluminum oxide as a pH sensor. Sensing films were fabricated by anodic oxidation, a process which is low cost, in which it is simple to manufacture and mass produce films at room temperature, in which it is easy to control the variation in film resistance. The films have a good linear sensitivity, approximately 56 mV/pH from pH 4 to 10 when an instrumentation amplifier is used as the read out circuit. This study indicates that the type of aluminum substrate affects the sensing characteristics. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis show that aluminum oxides on different aluminum substrates formed by anodic oxidation have various acid-base characteristics. Extended-gate field-effect transistor (EGFET) sensing films formed when the predominant surface plane of the aluminum oxide is (012) have a linear sensitivity.