In this study, we have used a direct immunoassay where the simple binding between antigen and an antibody is detected. Immunoassays were performed in a drop system, monitoring the frequency decrease of the quartz-crys...In this study, we have used a direct immunoassay where the simple binding between antigen and an antibody is detected. Immunoassays were performed in a drop system, monitoring the frequency decrease of the quartz-crystal microbalance device because of mass increasing during immunoreaction. The QCM sensor was coated on both sides by gold electrodes, only one side of the crystal (liquid side) was in contact with the solution;the other side (contact side) was always dry. We tested a piezoelectric immunosensor for aflatoxin B1 (AFLA-B1) mycotoxin detection through the immo- bilization of DSP-anti-AFLAB1 antibody (AFLA-B1-Ab anti AFLAB1) on gold-coated quartz crystals (AT-cut/5 MHz). The DSP (3,3’-Dithiodipropionic-acid-di-N-hydroxysuccinimide ester) was used for the covalent attachment of the proteins. The piezoelectric crystal electrodes were pretreated by DSP for 15 min, rinsed with water and dried in a gentle flow of nitrogen gas. Then the DSP-coated crystals were installed in a sample holder and exposed to the anti-AFLAB1 antibody and to the AFLA-BI. Frequency and resistance shifts (Δf and ΔR) were measured simultaneously. Δf versus AFLA-BI concentrations in the range of 0.5 - 10 ppb exhibited a perfect linear correlation with a coefficient of above 0.998.展开更多
A sensor based on the technique of a piezoelectric quartz crystal microbalance (QCM) is analyzed for the detection of six organic volatile compounds with high olive oil sensory significance, such as hexanal, acetic ac...A sensor based on the technique of a piezoelectric quartz crystal microbalance (QCM) is analyzed for the detection of six organic volatile compounds with high olive oil sensory significance, such as hexanal, acetic acid, Z-3-hexenyl acetate, undecane, 1-octen-3-ol and 2-butanone. Four sample concentrations have been exposed to each QCM sensor constructed. The detection system is based on the sample adsorption on the forty sensing films coated at the surfaces of forty AT-cut gold-coated quartz crystals. Each sensing film has been prepared with different solution concentrations of ten materials, usually used as chromatographic sta-tionary phases. Sensing film coating process shows excellent repeatability, with coefficient values less than 0.50%. The frequency shifts of the piezoelectric crystals due to the adsorption of the volatile compounds have been measured as sensor responses, using a static measurement system. The results show that only five QCM sensors, with high sensitivity values, are enough to the detection of the volatile compounds studied. Therefore, the developed detection system presented herein provides a rapid identification of organic volatile compounds with elevated olive oil sensory connotation and it could be a substitute technique to the analytical methods normally used for the analysis of the olive oil flavor.展开更多
Pd was electrochemically deposited on gold-coated quartz crystals at nanogram-level. The coulombic efficiency and initial nucleation and growth mechanism of potentiostatic Pd deposition were investigated via in situ e...Pd was electrochemically deposited on gold-coated quartz crystals at nanogram-level. The coulombic efficiency and initial nucleation and growth mechanism of potentiostatic Pd deposition were investigated via in situ electrochemical quartz crystal microbalance（EQCM）. The coulombic efficieneies are 84%, 93% and 95% for Pd deposition at 0.3, 0.2 and 0.1 V（vs. SCE）, respectively. The results of chronoamperometric measurements show that the Pd deposition proceeded by an instantaneous nucleation（at 0.3 V） or progressive nucleation（at 0.2 and 0.1 V） in a three-dimensional（3D） growth mode. The catalytic activity of Pd-based electrocatalyst for ethanol oxidation was characterized in an alkaline solution. It was found that the highest mass activity for ethanol oxidation on Pd-based electrocatalyst is 1.8× 10^4 A/（g Pd） deposited at 0.3 V for 5 s.展开更多
We have investigated the interactions between phospholipid monolayers and volatile anest-hatics. Two monolayers (dihexadecyl phosphate (DHP) and dipalmitoyl phosphatidyl choline (DPPC) and two anesthetics (halothane a...We have investigated the interactions between phospholipid monolayers and volatile anest-hatics. Two monolayers (dihexadecyl phosphate (DHP) and dipalmitoyl phosphatidyl choline (DPPC) and two anesthetics (halothane and enflurane) were used to observe these interac-tions using a highly sensitive quartz crystal microbalance (HS-QCM). The concentration of each anesthetic in aqueous solution was kept at 4 mM. The frequency of QCM showed no change when halothane was added to the DHP monolayer, however, it responded and de-creased when interaction occurred with DPPC monolayer. In case of enflurane addition the frequency decreased in both the monolayers of DHP and DPPC. The frequency change followed the following order of monolayer-anesthetic interactions: DHP-halothane <DPPC-halothane <DHP-enflurane <DPPC-enflurane. These re-sults showed that the response of anesthetics to the monolayers i.e. the physisorption not only depends on the anesthetic structure, the type of anesthetic hydrate formed, but also the hydrophilic polar group structure of the monolayer or the monolayer/water interface had an important role in physisorption.展开更多
The gravimetric analysis of electrodeposited nickel is demonstrated using electrochemical quartz crystal microbalance (EQCM) where the nickel coatings come from a solution of the metal chloride salt separately in eith...The gravimetric analysis of electrodeposited nickel is demonstrated using electrochemical quartz crystal microbalance (EQCM) where the nickel coatings come from a solution of the metal chloride salt separately in either a1choline chloride: 2 ethylene glycol (ethaline) or 1 choline chloride: 2 urea (reline) based ionic liquid. The possibility of adapting the Quartz Crystal Microbalance EQCM (which measures the mass attached to the electrode) to probe kinetics of electrochemically-driven solid state phase transformations has been explored in a Ni electrodeposition in absence and presence of complexing agents ethylene diamine en and acetylacetonate acac from both electrolytes ethaline and reline. The study shows that the current efficiency and the rate of deposition of nickel coatings obtained from ethaline and reline baths in absence of brighteners en and acac are different, and the addition of en and acac to both ionic liquid solutions results in a significant decrease current. And the associated growth rate will also be decreased, suggesting that the en acac stops the formation and growth of Ni nuclei. This suggests that the mechanism of growth is changed.展开更多
文摘In this study, we have used a direct immunoassay where the simple binding between antigen and an antibody is detected. Immunoassays were performed in a drop system, monitoring the frequency decrease of the quartz-crystal microbalance device because of mass increasing during immunoreaction. The QCM sensor was coated on both sides by gold electrodes, only one side of the crystal (liquid side) was in contact with the solution;the other side (contact side) was always dry. We tested a piezoelectric immunosensor for aflatoxin B1 (AFLA-B1) mycotoxin detection through the immo- bilization of DSP-anti-AFLAB1 antibody (AFLA-B1-Ab anti AFLAB1) on gold-coated quartz crystals (AT-cut/5 MHz). The DSP (3,3’-Dithiodipropionic-acid-di-N-hydroxysuccinimide ester) was used for the covalent attachment of the proteins. The piezoelectric crystal electrodes were pretreated by DSP for 15 min, rinsed with water and dried in a gentle flow of nitrogen gas. Then the DSP-coated crystals were installed in a sample holder and exposed to the anti-AFLAB1 antibody and to the AFLA-BI. Frequency and resistance shifts (Δf and ΔR) were measured simultaneously. Δf versus AFLA-BI concentrations in the range of 0.5 - 10 ppb exhibited a perfect linear correlation with a coefficient of above 0.998.
文摘A sensor based on the technique of a piezoelectric quartz crystal microbalance (QCM) is analyzed for the detection of six organic volatile compounds with high olive oil sensory significance, such as hexanal, acetic acid, Z-3-hexenyl acetate, undecane, 1-octen-3-ol and 2-butanone. Four sample concentrations have been exposed to each QCM sensor constructed. The detection system is based on the sample adsorption on the forty sensing films coated at the surfaces of forty AT-cut gold-coated quartz crystals. Each sensing film has been prepared with different solution concentrations of ten materials, usually used as chromatographic sta-tionary phases. Sensing film coating process shows excellent repeatability, with coefficient values less than 0.50%. The frequency shifts of the piezoelectric crystals due to the adsorption of the volatile compounds have been measured as sensor responses, using a static measurement system. The results show that only five QCM sensors, with high sensitivity values, are enough to the detection of the volatile compounds studied. Therefore, the developed detection system presented herein provides a rapid identification of organic volatile compounds with elevated olive oil sensory connotation and it could be a substitute technique to the analytical methods normally used for the analysis of the olive oil flavor.
基金Supported by the Guangdong Science and Technology Key Projects, China(Nos.2007A010700001, 2007B090400032)Guangzhou Science and Technology Key Projects, China(Nos.2007Z1-D0051, SKT[2007]17-11) the Scientific Research Foundation for Young Teachers of the Sun Yat-Sen University, China(No.2006-31000-1131214)
文摘Pd was electrochemically deposited on gold-coated quartz crystals at nanogram-level. The coulombic efficiency and initial nucleation and growth mechanism of potentiostatic Pd deposition were investigated via in situ electrochemical quartz crystal microbalance（EQCM）. The coulombic efficieneies are 84%, 93% and 95% for Pd deposition at 0.3, 0.2 and 0.1 V（vs. SCE）, respectively. The results of chronoamperometric measurements show that the Pd deposition proceeded by an instantaneous nucleation（at 0.3 V） or progressive nucleation（at 0.2 and 0.1 V） in a three-dimensional（3D） growth mode. The catalytic activity of Pd-based electrocatalyst for ethanol oxidation was characterized in an alkaline solution. It was found that the highest mass activity for ethanol oxidation on Pd-based electrocatalyst is 1.8× 10^4 A/（g Pd） deposited at 0.3 V for 5 s.
文摘We have investigated the interactions between phospholipid monolayers and volatile anest-hatics. Two monolayers (dihexadecyl phosphate (DHP) and dipalmitoyl phosphatidyl choline (DPPC) and two anesthetics (halothane and enflurane) were used to observe these interac-tions using a highly sensitive quartz crystal microbalance (HS-QCM). The concentration of each anesthetic in aqueous solution was kept at 4 mM. The frequency of QCM showed no change when halothane was added to the DHP monolayer, however, it responded and de-creased when interaction occurred with DPPC monolayer. In case of enflurane addition the frequency decreased in both the monolayers of DHP and DPPC. The frequency change followed the following order of monolayer-anesthetic interactions: DHP-halothane <DPPC-halothane <DHP-enflurane <DPPC-enflurane. These re-sults showed that the response of anesthetics to the monolayers i.e. the physisorption not only depends on the anesthetic structure, the type of anesthetic hydrate formed, but also the hydrophilic polar group structure of the monolayer or the monolayer/water interface had an important role in physisorption.
文摘The gravimetric analysis of electrodeposited nickel is demonstrated using electrochemical quartz crystal microbalance (EQCM) where the nickel coatings come from a solution of the metal chloride salt separately in either a1choline chloride: 2 ethylene glycol (ethaline) or 1 choline chloride: 2 urea (reline) based ionic liquid. The possibility of adapting the Quartz Crystal Microbalance EQCM (which measures the mass attached to the electrode) to probe kinetics of electrochemically-driven solid state phase transformations has been explored in a Ni electrodeposition in absence and presence of complexing agents ethylene diamine en and acetylacetonate acac from both electrolytes ethaline and reline. The study shows that the current efficiency and the rate of deposition of nickel coatings obtained from ethaline and reline baths in absence of brighteners en and acac are different, and the addition of en and acac to both ionic liquid solutions results in a significant decrease current. And the associated growth rate will also be decreased, suggesting that the en acac stops the formation and growth of Ni nuclei. This suggests that the mechanism of growth is changed.
