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Study Design: Retrospective observational study.Purpose: In this study we identify risk factors, including patient demographics, sagittal parameters, and clinical examinations, affecting incomplete L5/S posterior lumbar interbody fusion (PLIF).Overview of Literature: The lumbosacral spine is considered to have an interbody fusion rate lower than that of the lumbar spine, but few studies have investigated the cause, including investigating the pelvis. We believe that pelvic morphology can affect L5/S interbody fusion of the lumbosacral spine.Methods: We observed 141 patients (61 men, 80 women; average age, 65.8 years) who had undergone PLIF and checked for the presence of L5/S interbody fusion. We investigated factors such as age, gender, the presence of diffuse idiopathic skeletal hyperostosis (DISH), fusion level, and grade 2 osteotomy, as well as pre-, post-, and post−preoperative L5/S disk height and angle, lumbar lordosis, Visual Analog Scale (VAS) score, Japanese Orthopaedic Association (JOA) score, and pelvic incidence (PI), comparing those with and without L5/S interbody fusion. In addition, we analyzed the patients classified into short-level (n=111) and multi-level fusion groups (n=30).Results: Overall, the L5/S interbody fusion rate was 70% (short-level, 78%; multi-level, 40%). Age and pre- and post−preoperative L5/S disk angle were significantly different in each fusion level group. DISH presence, grade 2 osteotomy, and postoperative VAS and JOA scores were significantly different in the short-level fusion group, whereas PI was significantly different in the multi-level fusion group.Conclusions: Incomplete union after L5/S PLIF correlates with advanced age, many fusion levels, and a large value of preoperative and a small value of post−preoperative L5/S disk angles.

This is the first report of conducting proof-of-concept study for amperometric acetyltransferase-based L-carnitine sensor by employing the thiol/disulfide exchange reaction. The carnitine acetyltransferase (CrAT) catalyzes the reaction between acetyl-CoA and L-carnitine to produce CoA which is difficult to detect directly by electrochemical methods owing to steric hindrance and electrostatic effect of CoA. The thiol/disulfide exchange reaction between CoA and cystamine was mediated in the enzymatic reaction to produce electrochemically detectable low molecular weight of cationic cysteamine. The sensor exhibited high sensitivity and selectivity for L-carnitine in the concentration range 0.28-50 µM with a limit of detection of 0.28 µM. This is a promising strategy for L-carnitine sensing in point-of-care testing applications.

The supporting effect of a N-doped carbon film induced superior crystallinity in electrodeposited Ni@Ni(OH)2 core–shell nanoparticles. This improvement resulted in a much higher regeneration rate of catalytic sites (NiOOH), leading to higher oxidation currents of sugars. Also, the overpotential of the maltopentaose (G5) oxidation reaction decreased significantly, probably due to the effect of the electrostatic interaction between NPs and G5.

Carbon materials have been widely used for electrochemical analysis and include carbon nanotubes, graphene, and boron-doped diamond electrodes in addition to conventional carbon electrodes, such as those made of glassy carbon and graphite. Of the carbon-based electrodes, carbon film has advantages because it can be fabricated reproducibly and micro- or nanofabricated into electrodes with a wide range of shapes and sizes. Here, we report two categories of hybrid-type carbon film electrodes for mainly electroanalytical applications. The first category consists of carbon films doped or surface terminated with other atoms such as nitrogen, oxygen and fluorine, which can control surface hydrophilicity and lipophilicity or electrocatalytic performance, and are used to detect various electroactive biochemicals. The second category comprises metal nanoparticles embedded in carbon film electrodes fabricated by co-sputtering, which exhibits high electrocatalytic activity for environmental and biological samples including toxic heavy metal ions and clinical sugar markers, which are difficult to detect at pure carbon-based electrodes.

Bicontinuous microemulsion (BME)-based hydrogel films were integrated with screen-printed electrodes (SPEs) comprising working, counter, and reference electrodes to form stand-alone, semi-solid-state electrochemical systems that do not require an outer electrolyte solution. The gel network of the BME hydrogel only exists in the microaqueous phase and retains the structure of the entire BME gel. Following gelation, a microaqueous phase with sufficient ionic strength ensured effective ionic conductivity, even in thin gel films. This enabled the electrochemical reaction to proceed using a thin gel film as an electrolyte solution. However, an intact micro-oil phase with no gel network enabled efficient extraction from an external oil solution and exhibited rapid electrochemistry that was comparable to that of a BME solution. Cyclic voltammograms of lipophilic redox species in oil using the gel-integrated SPE system demonstrated successfully in the oil itself and in the air with dropped oil onto the system.

The fouling of electrodes with large molecules and/or electrochemically oxidized biomolecules limits the potential applications of bioelectroanalysis. The present work examined the effects of various plasma treatments when applied to sputtered carbon film electrodes. This was done by assessing the electrode responses to serotonin, a neurotransmitter that can be adsorbed after electrochemical oxidation. Although the oxidation current of serotonin rapidly decreases after five potential cycles with 5-minute intervals at the untreated and H2O plasma-treated carbon films, the magnitudes of the currents were almost unchanged at the films after NH3 and NH3/H2O gas plasma treatments. Cyclic voltammetric measurements of Fe(CN)63−/4− before and after serotonin oxidation revealed that there are no detectable fouling with oxidized serotonin by either the NH3 or NH3/H2O treatment, unlike the case with untreated and H2O plasma-treated carbon film electrodes. Similar to the serotonin response, both 5-hydroxyindoleacetic acid and 5-hydroxytryptophol show improved stable responses after the NH3/H2O plasma treatment. X-ray photoelectron spectroscopy data suggest that the suppression of fouling might be due to the electrostatic repulsion between the amino group of serotonin and surface charges after the NH3 and NH3/H2O treatments, in addition to the effects of hydrophilic surfaces generated by the plasma treatments.

Introduction Surgical treatment of osteoporotic vertebral fracture (OVF) often involves older patients with various comorbidities; thus, attending physicians must pay special attention to the invasiveness of surgical procedures and possible perioperative complications. In this retrospective observational study, we investigated the relationship between OVF and diffuse idiopathic skeletal hyperostosis (DISH) by examining the clinical characteristics and surgical outcomes. Methods Subjects comprised 26 patients (14 men, 12 women) who underwent surgical treatment for OVF complicated by DISH. Vertebral injuries affected the thoracolumbar transitional vertebrae in 18 patients and the middle and lower lumbar vertebrae in eight patients. The clinical characteristics, surgical results, radiological assessments, and outcomes were evaluated on the basis of the levels of affected vertebrae and whether anterior column reconstruction (ACR) was performed. Results Visual Analog Scale (VAS) measurements improved from an average of 69.7 mm before surgery to 21.3 mm after surgery. 14 patients had neurological deficits, who exhibited improvements by one or more steps on the Frankel scale after surgery. Activities of daily living (ADLs) were maintained during the six-month period following surgery in 23 patients. Comorbidity was observed in 22 patients. 14 patients had perioperative complications, and six required additional surgery. Both operating time and blood loss volume were significantly higher in patients in the middle and lower lumbar vertebrae and ACR groups. Postoperative correction loss was also significantly lower in the ACR group. Conclusions Favorable degrees of improvement in neurological deficits and VAS were observed following surgery in patients with OVF complicated by DISH, and postoperative ADLs were maintained in 92% of the patients. Elderly men frequently presented with comorbidities, and the frequencies of patients with perioperative complications and those requiring additional surgery were high.

Antibiotic pollution in water has become an increasingly serious problem, posing a potentially huge threat to human health. Ofloxacin (OFL), norfloxacin (NOR), and enoxacin (ENX) are typical broad-spectrum quinolone antibiotics, which are frequently detected in various water environments. An electrochemical sensor is a rapid and effective tool to detect antibiotics in the aquatic environment. The molecular structure of target pollutants is an important factor affecting the detection performance of electrochemical sensors. Based on the electrochemical detection results of antibiotics (OFL, NOR, and ENX), we first used the molecular structure analysis method based on quantum chemistry to accurately identify the electronegativity and the electrocatalytic degree of the oxidizable (and non-oxidizable) functional groups of pollutants. We also clarified the influence mechanism of the molecular structure on the peak current and peak potential. These results can provide theoretical support for rapidly selecting electrodes with a suitable electrochemical window to efficiently detect trace organic pollutants (such as antibiotics) in water based on the molecular structure of the target pollutant.

Surface modification is recognized as one of the fundamental techniques to fabricate biosensing interfaces. This review focuses on the surface modification of carbon substrates (GC and HOPG) and silica with a close-packed monolayer, in particular. In the cases of carbon substrates, GC and HOPG, it was demonstrated that surface modification of carbon substrates with diazonium derivatives could create a close-packed monolayer similar to the self-assembled monolayer (SAM) formation with mercapto derivatives. Similarly, the potential of trialkoxysilanes to form a close-packed monolayer was evaluated, and modification with a close-packed monolayer tended to occur under milder conditions when the trialkoxysilanes had a longer alkyl chain. In these studies, we synthesized surface modification materials having ferrocene as a redox active moiety to explore features of the modified surfaces by an electrochemical method using cyclic voltammetry, where surface concentrations of immobilized molecules and blocking effect were studied to obtain insight for density leading to a close-packed layer. Based on those findings, fabrication of a biosensing interface on the silica sensing chip of the waveguide-mode sensor was carried out using triethoxysilane derivatives bearing succinimide ester and oligoethylene glycol moieties to immobilize antibodies and to suppress nonspecific adsorption of proteins, respectively. The results demonstrate that the waveguide-mode sensor powered by the biosensing interface fabricated with those triethoxysilane derivatives and antibody has the potential to detect several tens ng/mL of biomarkers in human serum with unlabeled detection method.

The dosages of drugs in newborn infants are small. Small dose necessitate consideration of the loss of drug when administered via feeding tube. In this study, we conducted a tube administration test for seven kinds of antiepileptic drugs and two kinds of potassium supplements using a neonatal feeding tube and investigated the drug loss using the collection rate. We also studied the differences in collection rates among different dosage forms and drugs to determine the more suitable dosage forms and drugs. We investigated three dosage forms: powder, fine granules or dry syrup (powdery form) drugs, powdery form drugs that have been pulverized (pulverized powdery forms), and pulverized tablets. Additionally, we investigated two potassium supplements to determine which was more suitable: potassium L-aspartate and potassium gluconate. For topiramate, only the powdery form caused tube obstructions; the collection rates of the pulverized powdery form and pulverized tablets were > 90%. All antiepileptic drugs other than topiramate that were tested had collection rates of about > 90%. Considering stability and pharmacokinetics, the more suitable dosage form for topiramate is pulverized tablets, whereas the more suitable dosage form for other antiepileptic drugs is powdery form. Collection rate of potassium gluconate was higher than that of potassium L-aspartate. The current study, which indicates that potassium gluconate powdery form is the more suitable drug, presents the more suitable dosage form and drug for administration via feeding tube to newborn infants. These results show that it is essential to evaluate passage through the tube using the collection rate.

Carbon materials containing nitrogen have been extensively studied as electrode materials for use in non-platinum cathodes of fuel cells due to their high electrocatalytic activity for oxygen reduction. The activity is strongly dependent on the structure of surface nitrogen-containing functional groups. Carbon film containing nitrogen is also suitable for analytical applications because of its low background noise and its electrocatalytic activity, which is superior to that of pure carbon film. Here, we fabricated sputter-deposited nanocarbon film with a nitrogen-containing group and estimated the efficacy of a surface nitrogen-containing group for detecting biomolecules. Two types of carbon films, one rich in graphite-like nitrogen-containing bonds and the other rich in pyridine-like bonds, were successfully fabricated without changing their nitrogen concentration, sp2/sp3 ratio or surface flatness. The carbon film rich in pyridine-like bonds shows a positive oxygen reduction peak of about 250 mV compared with pure carbon film and is also 200 mV more positive compared with film with graphite-like nitrogen-containing bonds. This indicates that pyridine-like bonds contribute more effectively to electrocatalytic activity than graphite-like nitrogen-containing bonds. For detecting biomolecules, carbon film rich in pyridine-like bonds also exhibits more negative peak potentials for the oxidation of NADH and l-ascorbic acid, suggesting that carbon film rich in pyridine-like bonds will show improved performance for detecting electroactive biomolecules.

The musty odor compound geosmin was electrochemically detected by using Pt nanoparticle (PtNP)-embedded nanocarbon (Pt-C) films formed with unbalanced magnetron (UBM) co-sputtering. The sputtered Pt components formed NPs (typically 1.53-4.75 nm in diameter) spontaneously in the carbon films, owing to the poor intermiscibility of Pt with carbon. The surface concentrations of PtNPs embedded in the nanocarbon film were widely controllable (Pt = 4.8-35.9 at%) by regulating the target powers of the Pt and carbon individually. The obtained film had a flat surface (Ra = 0.17-0.18 nm) despite the fact the PtNPs were partially exposed at the surface. Compared with a Pt film electrode, some Pt-C films exhibited higher electrode activity against geosmin although the surface Pt concentrations of these Pt-C films were much lower than that of the Pt film electrode, thanks to the wider potential window and lower background current that resulted from the ultraflat and stable carbon-based film prepared by UBM co-sputtering. Computational experiments revealed that the theoretical oxidation potential (Eox) value for geosmin was relatively similar to that obtained in electrochemical experiments using our Pt-C film electrode. Moreover, we also theoretically estimated the possible oxidation site of geosmin molecules and the advantage of the NP shape of the electroactive Pt parts as regards the electrochemical oxidation of geosmin. We successfully used the Pt-C film (10.6 at%) electrode to detect geosmin in combination with HPLC at a low detection limit of 100 ng L-1.

We report an electrochemical method for detecting low concentrations of lipopolysaccharide (LPS), based on amplified zinc (Zn) signals on a sputtered nanocarbon film electrode. The nanocarbon film ...

Co-sputtered Ni/Cu nanoalloy embedded in carbon film electrodes were applied to an isocratic high performance liquid chromatography (HPLC) electrochemical detector to analyze urinary sugar probes used to assess gastrointestinal permeability. Electrode activity was easily controlled by varying the amounts of embedded nanoalloys without changing the Ni/Cu ratio. The high electrocatalytic activity of a nanoalloy makes it possible to achieve a limit of detection (LOD) of several tens of nM, which is one or two orders of magnitude lower than that of conventional pulsed amperometric detection using a gold electrode (Au-PAD). Moreover, Ni/Cu nanoalloy embedded in carbon film exhibits higher resistivity to electrode fouling by artificial urine components than Au-PAD, indicating that our electrode is a promising material for detecting sugar probes in real urine samples even under normal amperometric conditions.

Properties of modified surface, behavior against salting-out effect, suppressive effect for protein nonspecific adsorption, and wettability were examined using various mercapto compounds bearing methyloligoethylene glycol, oligoethylene glycol, alkyl oligoethylene glycol, alkyl phosphoryl choline, alkyl inverse phosphoryl choline, and alkyl sulfobetaine moieties. The behavior against salting-out effect was examined using gold nanoparticle with PBS and NaCl aqueous solution. The suppressive effect for protein nonspecific adsorption was evaluated by SPR, and the wettability was measured on the SPR chip. The gold nanoparticle modified with 8C3EG, 12C4EG, 12CPC, 6CCP, and 12CCP showed excellent behavior against salting-out effect. The suppression of protein nonspecific adsorption was effective with 6EG, 12C4EG, 12CPC, and 12CS. On the other hand, the modified surface possessed high wettability except for the surface modified with M6EG. The results indicate that incorporation of alkyl group into surface modification materials is effective for the enhancement of behavior against salting-out effect and suppressive effect for protein nonspecific adsorption regardless of wettability. Among the zwitter ionic derivatives, inverse phosphoryl choline derivatives showed intriguing properties, high behavior against salting-out effect with high wettability but low suppressive effect for protein nonspecific adsorption.

This paper reports an on-chip electrochemical assessment of the DNA methylation status in genomic DNA on a conductive nanocarbon film electrode realized with combined bisulfite restriction analysis (COBRA). The film electrode consists of sp2 and sp3 hybrid bonds and is fabricated with an unbalanced magnetron (UBM) sputtering method. First, we studied the effect of the sp2/sp3 ratio of the UBM nanocarbon film electrode with p-aminophenol, which is a major electro-active product of the labeling enzyme from p-aminophenol phosphate. The signal current for p-aminophenol increases as the sp2 content in the UBM nanocarbon film electrode increases because of the π–π interaction between aromatic p-aminophenol and the graphene-like sp2 structure. Furthermore, the capacitative current at the UBM nanocarbon film electrode was successfully reduced by about 1 order of magnitude thanks to the angstrom-level surface flatness. Therefore, a high signal-to-noise ratio was achieved compared with that of conventional electrod...

The present study investigated whether the clinical pharmacokinetics of atorvastatin can be predicted from the results of microdosing study in Japanese patients with hypercholesterolemia whose SLCO1B1 and ABCG2 polymorphisms were analyzed. Forty seven statin-naive patients clinically indicated to LDL cholesterol-lowering therapy with atorvastatin were enrolled in a two-period crossover study. Microdose (100 μg) of atorvastatin was orally administered followed by therapeutic dose (10 mg) administration. Transport studies were performed with BCRP-expressing membrane vesicles. The dose-normalized plasma AUC following the therapeutic dose of atorvastatin was positively correlated with that following its microdose, but the AUC increased more than dose proportionally from microdose to therapeutic dose. The patients carrying SLCO1B1 c.521TC showed a significantly higher AUC compared with those carrying c.521TT following the microdose (175%) and therapeutic dose (139%). On the other hand, SLCO1B1 c.388G or ABCG2 c.421A variant alleles did not significantly affect the pharmacokinetics of atorvastatin. Atorvastatin showed ATP-dependent transport in BCRP-expressing membrane vesicles and it inhibited rosuvastatin transport with Ki of 6.3 ± 2.9 μM (mean ± SD). Microdosing study appears to be feasible to roughly estimate the pharmacokinetic and pharmacogenetic profiles of atorvastatin following the oral therapeutic dose in hypercholesterolemic patients.

Electrocatalytic performance of metal nanoparticles (NPs) has been studied to apply for electrochemical devices such as fuel cells and electrochemical sensors. We have developed metal NPs embedded carbon film electrodes by co-sputtering of metal and carbon [1]. Various kinds of metals including Pt, Pd, Au, Ni, Cu and their alloys can be fabricated in the carbon film by using unbalanced magnetron (UBM) sputtering and applied for detecting hydrogen peroxide, glucose [1], heavy metals [2,3] and sugar markers [4, 5]. The electrocatalytic activity of metal NPs can be modulated by changing electronegativity of substrate such as carbon electrodes. Here, we proposed Ni NPs electrodeposited on nitrogen containing carbon film electrodes. Method The carbon films were prepared by unbalanced magnetron sputtering equipment and then treated by N2 plasma. The surface of the films were characterized by XPS. Then NiNP was electrodeposited onto both plasma treated and untreated carbon films by changing the deposition potentials. The fabricated electrodes were potential cycled to sufficiently form surface Ni(OH)2 on the surface of NiNPs, then applied for measuring sugar oxidation such as glucose and oligosaccharide in alkaline solutions with different pH. Results and Discussion The nitrogen containing carbon film electrode show unique electrochemical performances including reduction of overpotentials for oxygen reduction and oxidation of some biochemicals such as NADH and L-ascorbic acid [6]. The films also show excellent biocompatibility to suppress the fouling of proteins during electrochemical measurements [7]. When we deposited NiNPs onto the nitrogen containing carbon film, the size of NiNPs became smaller by decreasing potential from -1000 to -1300 mV. Since the size of NiNPs at N2 plasma treated surface is larger than that at pure carbon film, we adjusted the potential to obtain similar NiNPs size on both N2 plasma treated and untreated carbon surfaces. After deposition, both electrodes were potential cycled between 0 and 0.70 V (vs Ag/AgCl) to form surface Ni(OH)2 , which is confirmed by HR-TEM, and HAADF-STEM-EDS images. The redox reaction peaks of Ni(OH)2 oxidation and NiOOH reduction is almost identical when the scan rate is slow (1 mV/s). However, the oxidation and reduction peaks shifted positive and negative directions, respectively at Ni(OH)2 modified untreated carbon film with increasing potential scan rate up to 100 mV/s. In contrast, peak separation increase at Ni(OH)2 modified N2 plasma treated carbon film is greatly suppressed suggesting fast redox reaction similar to at Ni(OH)2. We applied both NiNPs deposited plasma treated and untreated carbon film electrodes for electrocatalytic oxidation of glucose and maltopentaose (G5) in alkaline media. Higher electrocatalytic oxidation currents of glucose was observed at NiNPs on nitrogen containing carbon film compared with those at NiNPs on untreated carbon film particularly in higher glucose concentration region (> 1mM). Moreover, the electrocatalytic current was started to increase sharply at +0.28 V at the Ni@Ni(OH)2-NP/N-C, while that at Ni@Ni(OH)2-NP/C was started to increased gradually at +0.34 V. These results could be due to the slightly formed NiOOH at the low potential region which cannot be detected as current change.And 60 mV potential difference could be interpreted as electrostatic interaction between G5 and electrode surface. In conclusion, the electrocatalytic activity of NiNPs can be enhanced by modifying NiNPs on the N2 plasma treated carbon films, which shows enhanced current and lower onset potential for electrocatalytically oxidation of G5. References [1] T. You, O. Niwa, M. Tomita, S. Hirono,” Characterization of platinum nanoparticle- embedded carbon film electrode and its detection of hydrogen peroxide”, Anal. Chem .,75 (2003) 2080. [2] D. Kato, T. Kamata, D. Kato, H. Yanagisawa, O. Niwa, “Au nanoparticle-embeded carbon films for electrochemical As3+ detection with high sensitivity and stability”, Anal. Chem ., 88 (2016) 2944. [3] S. Shiba, S. Takahashi, T. Kamata, H. Hachiya, D. Kato, O. Niwa, “Selective Au Electrodeposition on Au Nanoparticles Embedded in Carbon Film Electrode for Se(IV) Detection” Sensors and Materials ., 31 (2019) 1135. [4] S. Shiba, D. Kato, T. Kamata, O. Niwa,” Co-sputter deposited Nickel-Copper bimetallic nanoalloy embedded carbon films for electrocatalytic biomarker detection”, Nanoscale , 8 (2016) 12887. [5] S. Shiba, R. Maruyama, T. Kamata, D. Kato, O. Niwa, “Chromatographic determination of sugar probes used for gastrointestinal permeability test by employing nickel-copper nanoalloy embedded in carbon film electrodes”, Electroanalysis , 30 (2018) 1407. [6] T. Kamata, D. Kato, O. Niwa,”Electrochemical performance at sputter-deposited nanocarbon film with different surface nitrogencontaining groups”, Nanoscale, 11 (2019) 10239. [7] S. Ohta, S.Shiba, T. Yajima, T. Kamata, D. Kata, O. Niwa, “Gas-phase Treatment Methods for Chemical Termination of Sputtered Nanocarbon Film Electrodes to Suppress Surface Fouling by Proteins”, J. Photopolym. Sci. Tech., 32 (2019) 523

Bicontinuous microemulsions (BMEs, Winsor III), also called middle-phase microemulsions, are low-viscosity, isotropic, thermodynamically stable, and spontaneously formed mixtures of water, oil, and surfactants. They are unique solution media for electrochemistry. Here, we introduce the recent progress in the electrochemistry of BMEs from their fundamental aspects to their practical applications. Electrochemistry using BMEs has two irreplaceable properties: the coexistence of hydrophilic and lipophilic species with high self-diffusion coefficients; and the dynamic deformation of structures at an oil/water/electrode ternary interface, which is easily changed according to the property of the electrode surface. Electrochemical contact with the micro-saline and oil phases in a BME is alternately or simultaneously achieved by controlling the hydrophilicity and lipophilicity of the electrode surfaces. The selective electrochemical analysis of hydrophilic and lipophilic antioxidants in liquid foods without extraction demonstrated as the use of the unique ternary solution structures of BME on solid surfaces.

An electrochemical drug metabolizing sensor device was fabricated with a patterned electrode of polycrystalline indium tin oxide (pITO) film and a poly(dimethylsiloxane) (PDMS) thin layer microchannel. The pITO film is known to be suitable as an electrode for detecting direct electron transfer (DET) from cytochrome P450 (CYP) without any surface modification. However, the ITO surface is hydrophilic and this causes the CYP to detach from it, resulting in poor repeatability. This manuscript describes the simultaneous electrochemical measurement of drug metabolizing reactions that is achieved by continuously supplying the pITO electrode surface with a small amount of microsome CYP. To achieve this, the microchannel was evaluated for its flow uniformity and reproducibility, and the shape and dimensions needed for good performance were determined by using a highly uniform nickel mold obtained by employing a polishing process after electroplated mold fabrication. A clearly separated dual flow was established with the microchannel. Using dual pITO working electrodes arranged in parallel (dual flow measurement) and subtraction process, the current from only the drug metabolism reaction was obtained by introducing drugs and microsome CYP at one pITO electrode and introducing only microsome CYP at the other pITO electrode. We also performed a kinetic analysis of the CYP activity in our electrochemical microfluidic device.

We describe a current amplification system that employs a fluorinated nanocarbon (F-nanocarbon) film electrode formed by unbalanced magnetron (UBM) sputtering with a short CF 4 plasma treatment. The F-nanocarbon film exhibited the typical electrochemical reaction of a ferrocene-based mediator while strongly suppressing the electrochemical oxidation of Fe 2+ ions. This selectivity provided the current amplification of ferrocene mediators with Fe 2+ ions solely by using the F-nanocarbon film electrode without interference from the direct oxidation current of Fe 2+ ions. The current amplification system was used to realize an electrochemical biosensor with superior performance for detecting lipopolysaccharides. A detection limit of 2 ng mL −1 with good reproducibility (RSD of 4.2%) was achieved thanks to the very low noise made by possible by the ultraflat and hydrophobic surface.

Electrochemical deposition has been the preferred method to use for the soft templating of nanoporous metal thin film because of its low-temperature metallization processes, which prevent damage to the structures not only of soft templates, including self-assembled surfactants or copolymers, but also of the formed nanoporous metals. Recently developed soft-templating methods are based on the replication of highly ordered micelle assemblies composed of surfactants or copolymers. However, it is still difficult to achieve wide size control over 100 nanometers by soft templating, though such control is necessary for electrocatalytic or biosensing applications. We report on the fabrication of monolithic nanoporous gold (Au) thin films by electrodeposition in bicontinuous microemulsion (BME) as a dynamic soft template (Figure (a)). Au electrodeposition occurs only at the aqueous phase of BME, which has intertwined nanometer-ordered three-dimensional networks composed of aqueous and oil solution channels compartmentalized by surfactants and cosurfactants. The thermodynamically stable BME can be formed simply by “mixing” together of the components, and the solution/solution structure of BME could be controlled simply by changing the BME composition. We prepared three kinds of BME solutions, including water-rich BME (water/oil ratio: 66/34), oil-rich BME (33/67), and equally mixed BME (69/31), by mixing 5.00 mL of 1 M hydrochloric acid solution containing 50 mM tetrachloroaurate(III), 5.00 mL cyclohexane, 0.40 g sodium dodecyl sulfate (SDS), and different volumes of 2-methyl-2-butanol (470, 590, and 510 μL, respectively) as cosurfactants. Figure (b-d’) shows the top surface and cross-sectional FE-SEM images of the resultant gold thin film electrodeposited onto sputtered Au film at -0.30 V vs. Ag/AgCl for 300 sec in (a) oil-rich BME, (b) equally mixed BME, and (c) water-rich BME, respectively. The resultant Au films each had a unique monolithic nanostructure grown vertically to the electrode surface. The characteristic ligament diameters of these films increased from 40 to 200 nm as the aqueous solution content increased. These results clearly indicate that BME no doubt behaved as a soft template and successfully demonstrate that structural control can be easily achieved by changing the BME solution/solution structure. In the case of equally mixed BME, we also confirmed that the ligament axial length was controllable between 180 and 650 nm by changing the electrodeposition time from 200 to 400 s. The cross-sectional observation of all the films revealed that there were no side pores even though BME had a reticulated solution structure on the order of 100 nm or less. This indicates that monolithic BME structures changed continuously during electrodeposition depending on the film surface morphology and acted as dynamic soft templates. We conducted voltammetric experiments to assess surface characteristics such as electrochemically active surface area (ECSA), exposed facets, and electrocatalytic activity. The apparent electrode area of each Au film was defined by putting insulating tape with a 2-mm-diameter hole on the electrode surface. The linear sweep voltammetry after forming a fully oxidized surface in 0.5 M H2SO4 solution revealed that the ECSA of the monolithic nanoporous Au film electrodeposited in equally mixed BME for 300 s was 4.2 times greater than that with the sputtered Au film (before electrodeposition). The cyclic voltammetry in the same solution revealed that the oxidation potential of the main peak current of the monolithic nanoporous Au thin film was lower (+1.08 V vs. Ag/AgCl) than that of sputtered Au thin film (1.29 V). These results indicate that the existence of well-exposed {100} facets and/or dominant step/kink sites at the monolithic nanoporous Au thin film probably derived from vertically grown, highly curved nanostructures. As a test reaction, the methanol oxidation reaction (MOR) was used to investigate the electrocatalytic performance of electrodeposited nanoporous Au films. The cyclic voltammetry obtained in the 0.5 M KOH aqueous solution in the absence and presence of 1 M methanol resulted in a 1.9 times larger peak top current (446 μA cm-2 app) at the monolithic nanoporous Au film than that of sputtered Au film due to high ECSA. Interestingly, the onset potential of MOR at the monolithic nanoporous Au film was -0.58 V, which is 0.20 V more negative than that at the sputtered Au film; this might derive from the {100} facets and/or the step/kink structure of the nanoporous Au film. Figure 1

Recently, the amount of carnitine in saliva has been considered a biomarker for pancreatic cancer. Traditional analytical instrument such as liquid chromatography and mass-spectroscopy (MS) has been employed for carnitine detection. Only FET based biosensor was reported for carnitine, but the limit of detection was far above the required concentration. Here, we describe a highly sensitive and selective enzyme biosensor that we have developed for carnitine by using an enzyme-modified electrode combined with cathodic stripping voltammetry. The biosensor exhibits high sensitivity because of the preconcentration on the gold electrode of CoA, which was generated by the enzymatic reaction between carnitine and acetyl coenzyme A (acetyl-CoA) with carnitine acetyltransferase. Although both acetyl-CoA and CoA can adsorb on the gold electrode, the potential difference of reductive desorption detects CoA selectively. Under optimized conditions, the biosensor exhibited a linear range from 0.025 to 25 μM with a detection limit (S/N = 3) of 0.025 μM for carnitine determination. Moreover, the recovery experiments determination results show a stable range from 96.6 to 97.2 %. This developed carnitine biosensor has a potential in clinical detection due to the excellent performance.