1-Butyl-3-Methylimidazolium Tetrafluoroborate Film as a Highly Selective Sensing Material for Non-Invasive Detection of Acetone Using a Quartz Crystal Microbalance.

Breath acetone serves as a biomarker for diabetes. This article reports 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]), a type of room temperature ionic liquid (RTIL), as a selective sensing material for acetone. The RTIL sensing layer was coated on a quartz crystal microbalance (QCM) for detection. The sensing mechanism is based on a decrease in viscosity and density of the [bmim][BF4] film due to the solubilization of acetone leading to a positive frequency shift in the QCM. Acetone was detected with a linear range from 7.05 to 750 ppmv. Sensitivity and limit of detection were found to be 3.49 Hz/ppmv and 5.0 ppmv, respectively. The [bmim][BF4]-modified QCM sensor demonstrated anti-interference ability to commonly found volatile organic compounds in breath, e.g., isoprene, 1,2-pentadiene, d-limonene, and dl-limonene. This technology is useful for applications in non-invasive early diabetic diagnosis.

Multichannel quartz crystal microbalance array: Fabrication, evaluation, application in biomarker detection.

A multichannel quartz crystal microbalance array (MQCM) with three pairs of gold electrodes was fabricated for detection of two biomarkers: acetone and nitric oxide (NO). The gold electrodes were deposited symmetrically on an AT-cut 10 MHz circular quartz plate using photolithography, sputtering, and lift-off technologies. The effect of gold layer thickness on MQCM performance was investigated and the optimized thickness was 101 nm. The simulation values of the electric parameters C0, Cq, Lq, and Rq in the Butterworth-Van Dike equivalent circuit for the MQCM device were 97 pF, 1.3 pF, 1.05 mH, and 9.8 Ω, respectively. Simulation values were in the theoretical range, which indicated that the fabricated MQCM device had good resonance performance. Two types of nanocomposites, titanium dioxide-multiwalled carbon nanotubes and cobalt (II)phthalocyanine-silica, were synthesized as sensing materials. The sensing mechanism is based on coordination adsorption of target molecules onto the sensing material, resulting in a resonant frequency shift of modified QCM sensor. A linear range from 4.33 to 129.75 ppmv for acetone was obtained and one from 5.75 to 103.45 ppbv for NO.

Integration of a miniature quartz crystal microbalance with a microfluidic chip for amyloid beta-Aß42 quantitation.

A miniature quartz crystal microbalance (mQCM) was integrated with a polydimethylsiloxane (PDMS) microfluidic device for on-chip determination of amyloid polypeptide-Aß42. The integration techniques included photolithography and plasma coupling. Aß42 antibody was immobilized on the mQCM surface using a cross-linker method, and the resonance frequency of mQCM shifted negatively due to antibody-antigen binding. A linear range from 0.1 µM to 3.2 µM was achieved. By using matrix elimination buffer, i.e., matrix phosphate buffer containing 500 µg/mL dextran and 0.5% Tween 20, Aß42 could be successfully detected in the presence of 75% human serum. Additionally, high temperature treatments at 150 °C provided a valid method to recover mQCM, and PDMS-mQCM microfluidic device could be reused to some extent. Since the detectable Aß42 concentration could be as low as 0.1 µM, which is close to cut-off value for Alzheimer patients, the PDMS-mQCM device could be applied in early Alzheimer's disease diagnosis.

Nasal mucosal care before and after nasal endoscopic surgery based on computational information system resource sharing technology.

This study presents an in-depth analysis on a machine-designed computational web-based information system, which was used to conduct nasal mucosal care before and after nasal endoscopic surgery for chronic sinusitis. The system was developed and implemented using the mainstream B/S structure model with a Java development framework and MySQL database. Sinus irrigation solution has been shown to be effective for postoperative flushing after nasal endoscopy, by eliminating mucosal edema and promoting mucosal epithelialization at the operative cavity, and it is currently a desirable method that deserves promotion. By comparing the time required for surgical cavity cleaning, the rinsing solution was shown to be key of the physical flushing effect in the initial period after nasal endoscopy. It could remove blood cemented and surgical cavity surface cemented skin and secretions. In addition, the sinus irrigation solution can accelerate the mucosal epithelialization of the operative cavity more effectively than compounded saline. It could effectively eliminate mucosal edema, restore its protective and defensive functions, and help local blood circulation, secretion absorption, mucosal growth, mucosal regeneration and repair, and mucus cilia removal.

Tailoring the density of states of Ni(OH)2 with Ni0 towards solar urea wastewater splitting.

Solar urea wastewater splitting is capable of producing hydrogen and degrading the urea pollutant simultaneously. Nickel hydroxide (Ni(OH)2) has been recognized as an effective cocatalyst for the urea oxidation reaction (UOR). But the lack of an efficient preparation method and a suitable Ni(OH)2 based cocatalyst limits the performances of solar urea wastewater splitting. Herein, a potential-cycling method is developed with a high-purity nickel plate serving as the counter electrode and nickel source in a three-electrode configuration. Spherical Ni0-doped Ni(OH)2 nanoparticles are successfully synthesized on the surface of TiO2 nanorod arrays. The photocurrent density of TiO2/Ni0:Ni(OH)2 can reach 0.56 mA cm-2 at 1.23 VRHE in 1 M NaOH and 0.33 M CO(NH2)2 mixed electrolyte under AM1.5G illumination, which is 1.75 and 1.93 times those of TiO2/Ni(OH)2 deposited using a normal potentiostatic method with nickel salt solution and pristine TiO2, respectively. Ni0 doping can significantly decrease the charge transfer resistance and provide a more favorable distribution of density of states of Ni(OH)2 for the UOR. Furthermore, Ni0:Ni(OH)2 decorated TiO2 photoanodes exhibit good photocurrent retention during 12 h continuous testing. This work expands the preparation technique of urea catalysts and the strategy for developing highly efficient nickel-based catalysts.

Nanoporous platinum electrode grown on anodic aluminum oxide membrane: Fabrication, characterization, electrocatalytic activity toward reactive oxygen and nitrogen species.

A new type of nanoelectrode, nanoporous platinum (NPt) electrode was prepared on aluminum oxide membrane by thermal evaporation deposition. The morphology, conductivity and electrocatalytic activity of NPt electrode were characterized and compared with those of nanofilm-Pt electrode through scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques, respectively. SEM images showed that "nanocavities" observed in NPt electrode were actually 2-dimensional enclosures by linked nanoparticles. It was different from the conventional arrays of "nanocavities" formed on homogeneous metal films. EIS data indicated that NPt electrode possesses higher conductivity. Compared with that on nanofilm-Pt electrode (14.05 Ω·cm2), the impedance spectrum on NPt electrode exhibits a semicircle portion with much smaller diameters (1.24 Ω·cm2 for NPt-100, 1.48 Ω·cm2 for NPt-200). Meanwhile, the response sensitivity of NPt electrode to O2 is 0.85 mA cm-2, which is larger than that of nanofilm-Pt electrode (0.54 mA cm-2). The largest catalytic current for nitric oxide (NO) was obtained in buffer with pH value of 9.4 while for Angeli's salt (AS) was obtained in buffer with pH value of 5.4. Additionally, electrocatalytic mechanisms of NPt electrode toward NO and AS were proposed, which indicating it depended on pH value of buffer solution.

Preoperative P-wave duration as a predictor of atrial fibrillation after coronary artery bypass grafting: A prospective cohort study with meta-analysis.

OBJECTIVES: Reported prediction rules for postoperative atrial fibrillation (AF) have suffered from inconsistent results and controversy surrounding the predictive value of a preoperative P-wave duration (PreOPWD). This study examined PreOPWD as a predictor for AF after coronary artery bypass grafting (CABG). METHODS: Two-hundred-and-ninety-nine patients with sinus rhythm before off-pump CABG were recruited into the study. Patients' demographic and clinical data were evaluated prospectively. Patients were continuously monitored for the first seven postoperative days. Multiple logistic regression was used to determine significant predictors of AF. Findings were then combined with similar studies and a meta-analysis was performed. RESULTS: Postoperative AF was observed in 33.1% of 299 patients. Patients with AF were older, had a prolonged PreOPWD, higher incidences of hypertension, aortic regurgitation, and mitral regurgitation. A cut-off point of PreOPWD≥105 ms achieved a specificity of 74%, and a sensitivity of 65% for predictive of AF. Multivariate analysis showed that PreOPWD≥105 ms (odds ratio [OR] 4.63, 95% confidence intervals [CI] 2.66 to 8.03, P < 0.001), age≥60 years (OR 2.72, 95% CI 1.51 to 4.90, P < 0.01) and hypertension (OR 2.10, 95% CI 1.08 to 4.07, P < 0.05) independently predicted postoperative AF. A meta-analysis of this data combined with those of ten other studies showed that PreOPWD was greater in patients with POAF, with a weighted mean difference of 3.95 ms (95% CI 1.97 to 5.92, P < 0.001). CONCLUSION: This study confirmed, among other predictive characteristics, that PreOPWD is a powerful independent predictor of POAF.

Comparative study on the interaction of DNA with three different kinds of surfactants and the formation of multilayer films.

The interactions between double-stranded DNA (dsDNA) and three different kinds of surfactants, i.e., cationic, anionic, and nonionic surfactants, were investigated by cyclic voltammetry, electrochemical impedance spectroscopy and UV-vis spectroscopy. Multilayer films composed of DNA and surfactants were prepared at gold electrode by electrostatic or hydrophobic interactions. It was found that the cationic surfactant, CTAB, can bind to DNA by electrostatic interaction, and the electron transfer resistance of CTAB-DNA complex film increases first and then decreases with CTAB concentration. The anionic surfactant, LAS, can bind to DNA but by hydrophobic interaction, and the electron transfer resistance of the complex film keeps decreasing with LAS concentration. Nonionic surfactants can also directly bind to DNA by hydrophobic interaction. All the three different kinds of surfactants can form multilayer films with DNA on the electrode surface. The chemical structure of DNA keeps unchanged during interacting with these surfactants. The binding modes of DNA with these three different kinds of surfactants were also deduced.

Preparation, structure, and electrochemistry of a polypyrrole film doped with manganese(III)-substituted Dawson-type phosphopolyoxotungstate.

The fabrication, structure, electrochemical properties, and electrocatalytic properties of a manganese(III)-substituted Dawson-type phosphopolyoxotungstate, alpha 2-K7P2W17O61(Mn3+.OH2).12H2O (P2W17Mn), entrapped in polypyrrole (PPy) film have been studied. The hybrid film was prepared by potentiostatic polymerization from aqueous solution containing 20 mM pyrrole (Py) and 2 mM P2W17Mn on a pyrolytic graphite (PG) surface. Chronoamperometry, Raman spectroscopy, UV-visible absorption spectroscopy, and cyclic voltammetry were used to monitor and characterize the growth, structure, and properties of the film. The chronoamperometric curve shows that P2W17Mn can catalyze the electrochemical polymerization of Py. The Raman spectrum suggests that the doped P2W17Mn has little effect on the structure of PPy film. The P2W17Mn/PPy film exhibits good voltammetric response in both the acidic aqueous and acetonitrile solutions. At pH 1.0, the molar ratio of pyrrole to P2W17Mn7- in the hybrid film is 21.1:1, quite close to the expected ratio of 21.2:1 for a PPy film with a +0.33 oxidation level per pyrrole moiety and doped with an anion with a charge of 7. The influence of solution pH on P2W17Mn7- in the film is much smaller than that in the aqueous solution. During the potential scanning in 0.1 M LiClO4 acetonitrile solution, P2W17Mn7- was slowly released from the hybrid film and electrolyte ions (Li+ and ClO4-) were inserted into the film. This was identified by cyclic voltammetry and UV-visible spectroscopy. Additionally, the hybrid film can effectively catalyze the reduction of hydrogen peroxide and nitrite.

An amperometric glucose biosensor based on glucose oxidase immobilized in electropolymerized poly(o-aminophenol) and carbon nanotubes composite film on a gold electrode.

An amperometric glucose biosensor is developed that is based on immobilization of glucose oxidase (GOD) in a composite film of poly(o-aminophenol) (POAP) and carbon nanotubes (CNT), which are electrochemically co-polymerized at a gold (Au) electrode. Because of the high surface per volume ratio and excellent electrical conductivity of CNT, the biosensor based on an Au/POAP/CNT/GOD electrode has lower detection limit (0.01 mM), larger maximum response current (0.24 mA cm(-2)) and higher sensitivity (11.4 mA M(-1) cm(-2)) than the values of the biosensor based on an Au/POAP/GOD electrode. Additionally, the biosensor shows fast response time, large response current, and good anti-interferent ability for ascorbic acid, uric acid and acetaminophen. Good reproducibility and stability of the biosensor are also observed.

Study on the enhancement of catalytic activity for hemoglobin by quinhydrone in poly(o-aminophenol) film.

Hemoglobin (Hb) and quinhydrone (QHQ) were incorporated in poly(o-aminophenol) [o-AP, POAP] film by electropolymerization of o-aminophenol in a weak acid solution containing Hb and QHQ. The nonconducting polymer film was found to be nearly rigid by piezoelectric quartz crystal (PQC) impedance. Therefore, the thickness of the Hb-QHQ-POAP film was estimated as about 104 +/- 10 nm by quartz crystal microbalance (QCM). The QHQ mediation effects on the biomacromolecule Hb entrapped in the POAP film were investigated by using cyclic voltammetry, amperometric technique and kinetic study. Cyclic voltammograms showed that the redox peaks in the Hb-QHQ-POAP film are much more reversible than those in the Hb-POAP film. The response current of the Hb-QHQ-POAP film to H(2)O(2) was almost twice than that of the Hb-POAP film. The Michaelis-Menten constant and the activation energy of Hb in the Hb-QHQ-POAP film are 7.47 mM and 13.91 kJ/mol, respectively, both are smaller than that in the Hb-POAP film. These results showed that the immobilized Hb in POAP film exhibited higher catalytic activity to H(2)O(2) due to the mediation of QHQ.

Investigation of the effects of Au-colloid modification on cobalt hexacyanoferrate film growth and mass transport by electrochemical quartz crystal microbalance.

The growth of cobalt hexacyanoferrate (CoHCF) films on bare and Au-colloid-modified electrodes in nitrate or sulfate solutions was monitored by electrochemical quartz crystal microbalance. The average efficiency of CoHCF film growth for Au colloid modified electrodes is 23 and 12 ng cm(-2) s(-1) in KNO3 and K2SO4 solutions, respectively, while those values for the bare gold electrode are 15 and 9 ng cm(-2) s(-1), respectively. In K2SO4 solution, the apparent molar masses for the Au-colloid-modified electrode at lower and higher potential is 58.4 and 37.3 g mol(-1), respectively, which is larger than those for the bare gold electrode (51.7 and 26.3 g mol(-1), respectively). The respective results were also obtained in KNO3 solution. Furthermore, the difference of the apparent molar masses at lower and higher potential for Au-colloid-modified electrodes is smaller than that for bare gold electrodes in the same electrolyte. Additionally, the mechanism of charge propagation is dependent on different anions in electrolyte solutions at higher potentials where the second redox reaction of CoHCF occurs. Therefore, the existence of Au colloids can accelerate CoHCF film growth and weaken the effect of anions on mass transport.

Improved determination of 5-fluorouracil and its prodrug tegafur in pharmaceuticals by large-volume sample stacking in CE.

On-line determination of the anti-tumor drug 5-fluorouracil (5-FU) and its prodrug, tegafur (TF) was achieved for the first time by capillary electrophoresis with large-volume sample stacking (CE-LVSS). The optimal electrophoretic buffer consisted of 30 mM phosphate buffer at pH 8.0. Without the LVSS procedure, the limits of detection (LOD) were 600.5 ng/mL and 771.4 ng/mL for 5-FU and TF, respectively. With the LVSS procedure, the sensitivity was significantly improved by about two orders of magnitude (the LODs of 5-FU and TF were decreased to 7.9 ng/mL and 6.5 ng/mL, respectively). The %RSD was less than 5%. This method compared favorably with other reported techniques and was applied successfully to the quantitative analysis of anti-tumor drugs in commercial injection preparations. The results show that the method is simple, fast (less than 3 min), highly selective, and sensitive.

Polyoxometalate-modified carbon nanotubes: new catalyst support for methanol electro-oxidation.

A new catalyst support, polyoxometalate-modified carbon nanotubes, is presented in this paper through the chemisorption between polyoxometalate and carbon. Pt and Pt-Ru nanoparticles were electrochemically deposited on polyoxometalate-modified carbon nanotubes electrodes, and their electrocatalytic properties for methanol electro-oxidation are investigated in detail. Due to the unique electrical properties of carbon nanotubes and the excellent redox properties and the high protonic conductivity of polyoxometalate, for the similar deposition charge of Pt and Pt-Ru catalysts, 1.4 times larger exchange current density, 1.5 times higher specific activity, and better cycle stabilities can be obtained at polyoxometalate-modified carbon nanotube electrodes as compared to the electrodes without polyoxometalate modification. These results show that polyoxometalate-modified carbon nanotubes as a new catalyst support have good potential application in direct methanol fuel cells.

An amperometric hydrogen peroxide sensor based on immobilization of hemoglobin in poly(o-aminophenol) film at iron-cobalt hexacyanoferrate-modified gold electrode.

A series of hybrid iron-cobalt hexacyanoferrate (FeCoHCF) films were electrodeposited on gold electrodes from solutions containing 6mM Fe(CN)(6)(3-) with different concentrations of Co(2+) and Fe(3+). FeCoHCF films deposited from solutions with different molar ratios of iron were studied by cyclic voltammetry, and their solid states were characterized by Fourier transform infrared spectroscopy. The kind of FeCoHCF film that deposited from a solution with a molar ratio of iron of 0.4 showed the largest response current to H(2)O(2) and was characterized by energy-dispersive X-ray spectroscopy. Therefore, the optimized FeCoHCF film was combined with nonconducting poly(o-aminophenol) (POAP) film that entrapped the hemoglobin (Hb) to construct hydrogen peroxide biosensor. The response current of the Hb/POAP/FeCoHCF/Au electrode (29.8 nA) was nearly 40 and was 1.5 times that of the Hb/POAP/Au (0.7 nA) and POAP/FeCoHCF/Au (20 nA) electrodes, respectively. The Michaelis-Menten constant of Hb in the Hb/POAP/FeCoHCF/Au film was 9.31 mM. These results show that the immobilized Hb in the Hb/POAP/FeCoHCF/Au film exhibits higher catalytic activity and larger response current to H(2)O(2) by the mediation of FeCoHCF. In addition, effects of applied potential, solution pH, and electroactive interferent on the response current of the Hb/POAP/FeCoHCF/Au electrode were investigated in detail.

An amperometric glucose biosensor based on poly(o-aminophenol) and Prussian blue films at platinum electrode.

Prussian blue (PB), as a good catalyst for the reduction of hydrogen peroxide, has been combined with nonconducting poly(o-aminophenol) (POAP) film to assemble glucose biosensor. Compared with PB-modified enzymatic biosensor, the biosensor based on glucose oxidase immobilized in POAP film at PB-modified electrode shows much improved stability (78% remains after 30 days) in neutral medium. Additionally, the biosensor, at an applied potential of 0.0 V, exhibits other good characteristics, such as relative low detection limit (0.01 mM), short response time (within 5s), large current density (0.28 mA/cm2), high sensitivity (24 mAM(-1)cm(-2)), and good antiinterferent ability. The apparent activation energy of enzyme-catalyzed reaction and apparent Michaelis-Menten constant are 34.2 KJmol(-1) and 10.5 mM, respectively. In addition, effects of temperature, applied potential used in the determination, pH value of the detection solution, and electroactive interferents on the amperometric response of the sensor were investigated and are discussed.