Development of a QCM (Quartz Crystal Microbalance) Biosensor to the Detection of Aflatoxin B1

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.

Gravimetric Studies of Ni Electrodeposition with Additives from Deep Eutectic Solvents Using Electrochemical Quartz Crystal Microbalance EQCM

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.

Study of physisorption of volatile anesthetics on phos-pholipid monolayers using a highly sensitive quartz crystal microbalance (HS-QCM)

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.

Electrochemical Quartz Crystal Microbalance(EQCM) Characterization of Electrodeposition and Catalytic Activity of Pd-based Electrocatalysts for Ethanol Oxidation

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 efficiencies 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 1.8×104 A/(g Pd) deposited at 0.3 V for 5 s.

The influence of temperature on flow-induced forces on quartz-crystal-microbalance sensors in a Chinese liquor identification electronic-nose: three-dimensional computational fluid dynamics simulation and analysis

An electronic-nose is developed based on eight quartz-crystal-microbalance (QCM) gas sensors in a sensor box, and is used to detect Chinese liquors at room temperature. Each sensor is a highly-accurate and highly-sensitive oscillator that has experienced airflow disturbances under the condition of varying room temperatures due to unstable flow-induced forces on the sensors surfaces. The three-dimensional (3D) nature of the airflow inside the sensor box and the interactions of the airflow on the sensors surfaces at different temperatures are studied by computational fluid dynamics (CFD) tools. Higher simulation accuracy is achieved by optimizing meshes, meshing the computational domain using a fine unstructural tetrahedron mesh. An optimum temperature, 30 ℃, is obtained by analyzing the distributions of velocity streamlines and the static pressure, as well as the flow-induced forces over time, all of which may be used to improve the identification accuracy of the electronic-nose for achieving stable and repeatable signals by removing the influence of temperature.

Characterization of Self-assembled Monolayers on Gold Electrode Using Electrochemical Quartz Crystal Microbalance

The electrochemical quartz crystal microbalance (EQCM) is used to investigate the characteristics of the thiolated self-assembled monolayer(SAM) on gold surface.A 5MHz QCM element serves as both the mass-sensitive sensor and the working electrode of the electrochemical system.The 6-mecapto-1-hexanol and and the 16-mer oligonucleotide with a mercaptohexyl group at the 5'-phosphate end are utilized to form the SAM on the gold electrode.The frequency response of the QCM during cyclic voltammetry (CV) scanning and cbronoamperometry are recorded together with the electrochemical current.The experimental results indicates that the frequency response is more sensitive to the surface coverage.Therefore,the response of the EQCM reveals more details of the SAM on gold electrode.It is especially useful for analysing the immobilization quality,such as probe orientation and coverage,of the SAM.

Quartz Crystal Microbalances for Evaluating Gas Motion Differences between Dichlorosilane and Trichlorosilane in Ambient Hydrogen in a Slim Vertical Cold Wall Chemical Vapor Deposition Reactor

A dichlorosilane gas and a trichlorosilane gas in ambient hydrogen were evaluated to show their different gas flow motions in a slim vertical cold wall chemical vapor deposition reactor for the Minimal Fab system. This evaluation was performed for improving and controlling the film qualities and the productivities, using two quartz crystal microbalances (QCM) installed at the inlet and exhaust of the chamber by taking into account that the QCM frequency corresponds to the real time changes in the gas properties. Typically, the time period approaching from the inlet to the exhaust was shorter for the trichlorosilane gas than that for the dichlorosilane gas. The trichlorosilane gas was shown to move like plug flow, while the dichlorosilane gas seemed to be well mixed in the entire chamber.

Rapid identification of spinal ventral and dorsal roots using a quartz crystal microbalance

The fast and accurate identification of nerve tracts is critical for successful nerve anastomosis.Taking advantage of differences in acetylcholinesterase content between the spinal ventral and dorsal roots,we developed a novel quartz crystal microbalance method to distinguish between these nerves based on acetylcholinesterase antibody reactivity.The acetylcholinesterase antibody was immobilized on the electrode surface of a quartz crystal microbalance and reacted with the acetylcholinesterase in sample solution.The formed antigen and antibody complexes added to the mass of the electrode inducing a change in frequency of the electrode.The spinal ventral and dorsal roots were distinguished by the change in frequency.The ventral and dorsal roots were cut into 1 to 2-mm long segments and then soaked in 250 μL PBS.Acetylcholinesterase antibody was immobilized on the quartz crystal microbalance gold electrode surface.The results revealed that in 10 minutes,both spinal ventral and dorsal roots induced a frequency change;however,the frequency change induced by the ventral roots was notably higher than that induced by the dorsal roots.No change was induced by bovine serum albumin or PBS.These results clearly demonstrate that a quartz crystal microbalance sensor can be used as a rapid,highly sensitive and accurate detection tool for the quick identification of spinal nerve roots intraoperatively.

Quartz Crystal Microbalance Sensor Deposited with LB Films of Functional Polymers for the Detection of Phenols in Vapour Phase

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Hybrid temperature effect on a quartz crystal microbalance resonator in aqueous solutions

The quartz crystal microbalance(QCM) is an important tool that can sense nanogram changes in mass. The hybrid temperature effect on a QCM resonator in aqueous solutions leads to unconvincing detection results. Control of the temperature effect is one of the keys when using the QCM for high precision measurements. Based on the Sauerbrey's and Kanazawa's theories, we proposed a method for enhancing the accuracy of the QCM measurement, which takes into account not only the thermal variations of viscosity and density but also the thermal behavior of the QCM resonator. We presented an improved Sauerbrey equation that can be used to effectively compensate the drift of the QCM resonator. These results will play a significant role when applying the QCM at the room temperature.

Application of Nanoparticles in Quartz Crystal Microbalance Biosensors

Nanoparticles are playing an increasingly important role in the development of biosensors. The sensitivity and performance of biosensors are being improved by using Nanoparticles for their construction. The use of these Nanoparticles has allowed the introduction of many new signal transduction technologies in biosensors. In this report, a comprehensive review of application of nanoparticles in Quartz Crystal Microbalance biosensors is presented. The main advantages of QCM in sensing fields include high sensitivity, high stability, fast response and low cost. In addition, it provides label-free detection capability for bio-sensing applications. Firstly, basic QCM’s design and characterization are described. Next, QCM biosensors based on modification of quartz substrate structure and their applications are digested. Nanoparticles and their utilizationin analysis are then illustrated. These include Nanoparticles in bio applications that cover Nanoparticles in Quartz Crystal Microbalance biosensors.

Fabrication and evaluation of a portable and reproducible quartz crystal microbalance immunochip for label-free detection ofβ-lactoglobulin allergen in milk products

In this study,a label-free,portable and reproducible immunochip based on quartz crystal microbalance(QCM)was developed for the qualitative detection ofβ-lactoglobulin(β-LG),an allergen,in milk products.Experimental parameters in the fabrication and regeneration procedure such as pH of the coupling microenvironment,amount of anti-β-LG antibody and regeneration reagent were optimized in detail.Under optimal conditions,the proposed QCM immunochip exhibited good recognition of β-LG,with a calibration curve of ΔF=12.877 C_(β-LG)^(0.4809)(R^(2)=0.9982)and limit of detection of 0.04μg/mL.Additionally,this portable QCM immunochip had good stability,high specificity,and no obvious cross-reaction to three other milk proteins(α-casein,α-lactalbumin,and lactoferrin).It could compete a qualitative measurement within5 min,and could be reused at least ten times.In the β-LG analysis of actual milk samples,the developed QCM immunochip yielded reliable and accurate results,which correlated strongly with those from the standard HPLC method(R^(2)=0.9969).Thus,the portable,stable,and reproducible QCM immunochip developed in this study allowed the rapid,cost-effectively and sensitively measure theβ-LG in milk products.

Determination of Paclitaxel Solubility in Carbon Dioxide Using Quartz Crystal Microbalance

一杆石英水晶微量天秤(QCM ) 被用来在 011 MPa 并且在 35 的温度的压力范围决定 paclitaxel 碳二氧化物系统的阶段平衡 ? 吗？？

In situ Investigation on Layer-by-Layer Deposition of Polyelectrolytes by Quartz Crystal Microbalance

layer-by-layer 免职上的盐集中的效果(钠 4 苯乙烯 sulfonate )(PSSS ) poly， /poly (vinylbenzyl trimethylammonium 氯化物)(PVTC ) 被石英水晶微量天秤的使用与驱散(QCM-D ) 调查。在频率和驱散的变化证明 NaCl 的增加导致多层的 PSSS/PVTC 的厚度增加。PSSS/PVTC 的免职被表面费用过度补偿水平在更低的盐集中统治。然而，它被聚合电解质的互相贯通主要在更高的盐集中决定，在驱散变化的摆动思考了。

Quantitative measurement of p53-p53 antibody interactions by quartz crystal microbalance: A modelsystem for immunochemical calibration

We are developing methods to quantify antibody interactions that include a quartz crystal microbalance (QCM) system to measure, on a molecular basis, the interaction of p53 and anti-p53 antibodies. Previously, as a model system, we developed a measurement device consisting of p53 protein (human wild type), characterized by mass spectroscopy and immobilized at various concentrations on a glass slide. The device is designed as a control to be used with immunohistochemical (IHC) assays that incorporate commercially available anti-p53 antibodies and probes. In the current study, p53 protein is covalently immobilized on a silicon dioxide-coated quartz crystal and the resonance frequency shift is followed in-situ. The functionalized sensor is then incubated with the anti-p53 antibody, which provides a direct gravimetric measure of the antibody-antigen binding. This previously described method allows the comparison of the surface immobilized protein concentrations with estimates obtained by fluorescence measurement. The p53 functionalized QCM system offers an independent measure of surface immobilized protein concentration and is essential in development of our IHC calibration prototypes. These results provide a benchmark for comparing antibody systems that may be used in developing other molecular diagnostic assays such as immunocytochemical analysis and the detection of biomarker proteins in blood and urine.

Charge Transport Processes of Immobilized Heteropolyanions at Self-assembled Monolayer Modified Gold Electrode by Electrochemical Quartz Crystal Microbalance Measurement

The in situ electrochemical quartz crystal microbalance(EQCM) technique was used to investigate the ion transport of immobilized heteropolyanions at a self-assembled monolayer(SAM) modified gold electrode during electrochemical redox process.A mixed transfer method was presented to analyse the abnormal change of resonant frequency based on the simultaneous insertion/extraction of different ions.The results indicate that the migration of HSO4-anions was indispensable in the redox process of the heteropolyanions in a 1 mol/L H2SO4 solution and played a key role in the abnormal change of the resonant frequency.Such a change was attributed to different packing densities derived by means of differently immobilized methods.

Real-Time Characterization of Fibrinogen Interaction with Modified Titanium Dioxide Film by Quartz Crystal Microbalance with Dissipation

因为它的突出的角色，纤维蛋白原的吸附能在凝结和血小板粘附被用作表面 haemocompatibility 的快指示物。在这个工作，在纤维蛋白原和一块修改的钛氧化物表面 / 血小板之间的分子的相互作用被石英水晶微量天秤在 situ 与驱散(QCM-D ) 学习了。为了进一步描绘吸附的纤维蛋白原， C 和链抗体的符合构造，被用来检查固体上的纤维蛋白原的取向和变性作用出现。QCM-D 调查揭示了纤维蛋白原有趋势由断然控告的 C 领域在站在一起上取向在吸水的表面上吸附，它将在链上减少血小板结合地点的暴露并且启用更少的血小板粘附并且被激活。这些观察建议吸附的纤维蛋白原的某些符合构造比其它是更少的血小板粘合剂，它为创造非血小板粘合剂打开可能性底层。

基于QCM液体密度响应模型测量油品含水率研究

油田开发中一直存在高含水率和低含水率测量不准确的问题,新型可再生的生物柴油,同样需要控制含水率以保证热值和稳定性。文中提出一种基于石英晶体微天平(QCM)液体密度响应模型的油品含水率测量方法,通过5组标准甘油溶液进行模型验证,结果表明,实验值与理论值的误差小于5%,并且在低含水量和高含水量2种情况下,误差幅度小于1%。重复性实验验证了模型的有效性。现场测量实验结果证实了模型的适用性。

QCM传感器的应用研究进展

石英晶体微天平(QCM)是以压电效应为基础,通过电极频率变化对微量物质进行分析检测的仪器,其高灵敏度和实时反映电极频率变化的特点在检测微量物质、表征反应变化过程、快速检测中受到广泛关注,被应用于生物、医学、化学等各个领域中。根据QCM所应用的领域不同,分别阐述在医学检测、环境监测、食品检测的应用的研究进展,同时探讨了QCM现存的部分问题和未来的解决方向。