压电晶体传感器的研究进展

本文简要介绍了压电晶体传感器的基本原理,以及基于质量、粘度、电导率变化的溶液分析法。重点介绍了电化学石英晶体微天平（EQCM）、压电生物传感器;对具有很大发展潜力和重要应用价值的串联式压电传感器（SPQC）、串联式表面声波电导传感器（SAW）、液隔电极式压电传感器（ESPS）等也作了简要说明。     

Preparation and Application of Fullerene C60‐Polymers in Piezoelectric Quartz Crystal Sensors for Hemoglobin and Olefins

The C60—polycinnamaldehyde (C₆₀—PCA) and C60—polyphenylacetylene (C60—PPA) polymers were synthesized by the Friedel—Craft reaction and applied as piezoelectric (PZ) quartz crystal coating materials. A C60—polycinnamaldehyde (PCA) coated piezoelectric quartz crystal liquid sensor with a homemade computer interface was prepared and applied as a PZ hemoglobin sensor. The adsorption of hemoglobin onto the C60—PCA coated crystal resulted in a decreased oscillating frequency. The variations in crystal frequency were converted to voltage with a frequency to voltage converter, followed by amplification with OPA and data acquisition with an analog to digital converter. The PZ hemoglobin sensor exhibited good sensitivity of 6530 Hz/(mg/mL) with a detection limit at the ppm level for hemoglobin. Further, a C60—polyphenylacetylene (C60—PPA) coated piezoelectric quartz crystal gas sensor with an Intell‐8255 data processing system for various olefin vapors was also made. The aromatic hydrocarbons such as toluene seem to have greater adsorption onto C60—PPA membrane than alkynes, alkenes, and alkanes. The adsorption of polycyclic aromatic hydrocarbons (PAHs) onto the C60—PPA membrane was also examined. The C₆₀—PPA coated PZ crystal gas sensor showed much better sensitivity for PAHs than for other olefins such as toluene, 1‐hexyne and 1‐hexene, and a much larger frequency shift for naphthalene than other PAHs was also found.     

Piezoelectric Quartz Crystal Anti‐Protein Immunosensors Based on Immobilized Fullerene C60‐Proteins

Various fullerene C60‐proteins such as C60‐myoglobin (C60‐Mb), C60‐hemoglobin (C60‐Hb) and C60‐gliadin, coated piezoelectric quartz crystals were prepared and applied in piezoelectric quartz crystal immunosensors for protein‐antibodies such as anti‐myoglobin (Anti‐Mb), anti‐hemoglobin (Anti‐Hb) and anti‐gliadin respectively. The immobilizations of myoglobin, hemoglobin and gliadin onto Fullerene C60 were studied with a C60‐coated piezoelectric crystal detection system, respectively. The partially irreversible frequency responses for theses proteins were observed by a desorption study, implying that C60 can strongly adsorb these proteins. Thus, immobilized C60‐Mb, C60‐Hb and C60‐gliadin coating materials were successfully prepared and identified with FTIR spectrometry. The C60‐Mb, C60‐Hb and C60‐gliadin coated piezoelectric (PZ) quartz crystal immunosensors with homemade computer interfaces for signal acquisition and data processing were developed and applied for detection of Anti‐Mb, Anti‐Hb and anti‐gliadin respectively. The C60‐protein coated PZ immunosensors for Anti‐Mb, Anti‐Hb and antigliadin exhibited linear frequency responses to the concentrations of theses anti‐proteins with sensitivities of 1.43 × 10³, 2.59 × 10³ and 8.05 × 10³ Hz/(mg/mL) respectively. The detection limits of these PZ‐immunosensors were 4.36 × 10^?3, 3.23 × 10^?3 and 1.98 × 10^?3 mg/mL for Anti‐Mb, Anti‐Hb and anti‐gliadin respectively. Effects of pH and temperature on the frequency responses of the anti‐protein PZ‐immunosensors were also investigated. The optimum pH of these anti‐proteins and the optimum temperature for the PZ‐immunosensors were observed at pH = 7 and around 30 °C respectively. The interferences of various common species in human blood, e.g., cysteine, tyrosine, urea, glucose, ascorbic acid and metal ions, to these anti‐protein PZ‐immunosensors were also investigated respectively. These species showed nearly no interference or quite small interference with the anti‐protein PZ‐immunosensors. The reproducibility and lifetime of these immobilized C60‐protein coated PZ crystal immunosensors were also investigated and discussed.     

An Unexpected Frequency Response of A Piezoelectric Quartz Crystal Sensor to the Density and Viscosity of the Liquid

An unexpected frequency response for a piezoelectric quartz crystal (PQC) sensor to liquid density and viscosity was reported. For a PQC oscillating in a liquid phase, the frequency shifts (△f) show a wave-shape response to liquid density (p) and viscosity 03) in fine structure, ifthe longitudinal wave effect was not eliminated. This result is different from the well-knownlinear relationship between of Af and (ρη)1/2. An oscillating frequency-temperature curve of thesensor was observed and explained.     

间苯二酚杯[4]芳烃为涂层的压电石英传感器测定液相多巴胺

研究了以间苯二酚杯[4]芳烃为敏感涂层的石英压电晶体（PQC）传感器,在中 性磷酸盐缓冲液体系中对神经传递质多巴胺和抗坏血酸的响应,发现间苯二酚杯 [4]芳烃对多能上能下胺有很好的响应选择性,这归因于间苯二酚杯[4]芳烃与多巴 胺分子结构相匹配,形成主客体超分子体系。以间苯二酚杯[4]芳烃为涂层的POC传 感器对液相中多巴胺具有响应快、重现性好、灵敏度高的特点,线性响应范围为3. 5-500 μg/g。     

Design and Performance of a New Thin‐Layer Radial‐Flow Holder for a Quartz Crystal Resonator of an Electrochemical Quartz Crystal Microbalance

A new compact holder for either 5‐ or 10‐MHz AT‐cut quartz crystal resonator of an electrochemical quartz crystal microbalance was designed, fabricated and characterized. The holder is a hydrodynamically controlled thin‐layer radial‐flow microelectrochemical cell. Its unique feature consists of (i) a micrometer‐screw adjustable distance between the movable coaxial assembly of the Ag/Ag⁺ pseudoreference electrode and the inlet capillary nozzle with respect to the metal‐film working electrode of the quartz crystal resonator, and (ii) a U‐clamp mountable resonator, easily accessible for change without using any tools. The inlet solution stream is centered axially against the working electrode. The holder performance was tested under different flow conditions. These include hydrodynamic voltammetry measurements on the Fe(CN) /Fe(CN) couple, i.e., a redox system with no mass transfer across the solution–electrode interface, as well as simultaneous chronoamperometry and chronoelectrogravimetry measurements under flow injection analysis (FIA) conditions on the Ag/Ag⁺ couple, i.e., a system with electrodeposition of a rigid metallic film. Moreover, simultaneous changes of resonant frequency and dynamic resistance were measured under FIA conditions for a glycerol solution, i.e., an electroinactive viscous medium. For the 30<F_m<180 μL min^?1 volume flow rate of solution and 50<d<250 μm nozzle‐to‐resonator distance, the holder operates in a thin‐layer radial‐flow regime at a fully developed laminar flow. For F_m=30 μL min^?1 and d=100 μm, both mass and charge conversion accompanying silver electrodeposition is appreciably high and close to 35%. Simultaneous measurements of the resonant frequency change and current‐potential or current‐time transients allowed investigations of electrochemical processes involving mass changes of rigid deposits while those of the frequency change and dynamic resistance change involve changes of viscoelastic properties of medium.     

Piezoelectric Quartz Crystal Biosensors: Recent Immobilisation Schemes

ABSTRACT

A Mini Review on recent immobilisation techniques for the realisation of piezoelectric biosensors is presented. The reactions considered are affinity reactions such as DNA hybridisation and antigen/antibody systems. The immobilisation procedures considered are based on avidin-biotin interaction, adsorption and self-assembled monolayers.     

Multi‐Channel Piezoelectric Quartz Crystal Sensor with Principal Component Analysis and Back‐Propagation Neural Network for Organic Pollutants from Petrochemical Plants

A multi‐channel piezoelectric quartz crystal gas sensor comprising arrays coated with various organic materials and a home‐made computer interface for data processing were prepared and employed to detect six kinds of common organic pollutants from petrochemical plants including benzene, styrene, chloroform, octane, hexene and hexyne. The principal component analysis (PCA) method was employed to select six kinds of appropriate coating materials for these organic pollutants from 22 adsorbents onto piezoelectric crystals. After performing a PCA assay, six representative coating materials, namely Polyisobutylene, Poly(dimethylsiloxane) (SE30), 4‐tert‐Butylcalix[6]arene, Cholesteryl chloroformate, C60‐Polyphenyl acetylene (C60‐PPA) and Ag(I)/cryptand‐2,2/Ethylene diamine/NH₃/Polyvinyl chloride were selected. Moreover, effects of coating load of adsorbents and concentration of pollutants were also investigated. Three kinds of recognition techniques including 2D PCA score map, radar plot and back‐propagation neural network (BPN) were employed for qualitative analysis of these organic pollutants, and a quantitative analysis method could be established by creating calibration curves for each organic pollutant. This homemade multi‐channel piezoelectric quartz crystal gas sensor showed a good detection limit of 0.068‐1.127 mg/L for these organic pollutants. The multi‐channel piezoelectric gas sensor exhibited good reproducibility with a relative standard deviation (RSD) of 1.1‐9.6%. Furthermore, this multi‐channel piezoelectric crystal detection system with BPN recognition technique was also utilized to successfully distinguish and identify each component of the mixture of organic gas samples. Multivariate linear regression (MLR) analysis was employed to quantitatively compute the concentration of species in the organic mixtures.     

A Novel Ion-Selective Sensor for Procaine Hydrochloride Based on a Piezoelectric Quartz Crystal Coated with a Procaine Tetraphenylborate PVC Membrane

 A novel ion-selective sensor for procaine hydrochloride has been proposed and applied successfully to analysis of pharmaceutical preparations. The sensor is based on modification of the Ag-electrode of an AT-cut piezoelectric quartz crystal with a PVC membrane containing procaine tetraphenylborate. A linear relation between the logarithm of the response frequency and the logarithm of the procaine hydrochloride concentration was found experimentally and could be explained by combination of a modified Sauerbrey equation and the Freundlich isotherm. The detection range was from 8.3 × 10⁻⁸ to 5.0 × 10⁻³ M with a detection limit of 8.3 × 10⁻⁸ M. The selectivity of the sensor and the influence of experimental parameters such as solution pH and detection time were investigated. Received February 10, 1999. Revision October 10, 1999.     

Fullerene‐Crown Ether Coated Piezoelectric Crystal Liquid Chromatographic Detector for Metal Ions and Polar/Nonpolar Organic Molecules

Fullerene(C60)‐dibenzo‐16‐crown‐5‐oxyacetic acid (DBI6C5‐OCH₂‐COOC₆₀) was prepared and applied as the coating material on piezoelectric quartz crystals for detection of various metal ions and polar/nonpolar organic molecules. The C60‐crown ether‐coated piezoelectric crystal sensor with a home‐made computer interface for signal acquisition and data processing was applied as an ion chromatographic (IC) detector for various metal ions, e.g., alkali metal, alkaline earth metal and transition‐metal ions. The piezoelectric detector exhibited quite good sensitivity of 10⁴ ～ 10⁶ Hz/M and good detection limit of 10^?3 ～ 10^?4 M for these metal ions. The C60‐crown ether piezoelectric detector compared well with the commercial conductivity detector conventionally used for metal ions. The ionic size and ionic charge seemed to have significant effect on the frequency response of the piezoelectric detector. The C60‐crown ether coated piezoelectric crystal sensor was also employed as a high performance liquid chromatographic (HPLC) detector for various polar organic molecules with frequency responses in the order: amines > carboxylic acids > alcohols > ketones. Furthermore, nonpolar organic molecules, e.g., n‐hexane, 1‐hexene and 1‐hexyne, were also detected with this piezoelectric crystal detector. The frequency responses of the piezoelectric crystal detector for these nonpolar organic molecules were in the following order: alkynes > alkenes > alkanes. The effects of solvents and flow rate on the frequency responses of the piezoelectric crystal detector were investigated. The C60‐crown ether coated piezoelectric crystal detector also showed short response time (< 1 min.) and good reproducibility.     

Piezoelectric Crystal Liquid Flow Detection Systems Based on Alkyl (C18)‐Benzo‐15‐Crown 5 for Organic Compounds and Metal Ions

A water in soluble long‐chain crown ether alkyl (C18)‐benzo‐15‐crown‐5 was synthesized and applied as a coating material on quartz crystal membranes of a liquid flow piezo electric crystal sensor. The oscillating crown ether‐coated piezo electric (PZ) crystal with a home‐made computer inter face was prepared as a liquid chromato graphic (LC) detector for organic species and metal ions in aqueous solutions. The oscillating frequency of the quartz crystal decreased due to the adsorption of organic molecules or metal ions on crown ether molecules. Effects of functional group, molar mass, steric hindrance, and polarity of organic molecules on frequency responses of the crown ether coated PZ crystal detector were investigated. The frequency responses of the crown ether coated PZ crystal detector for various molecules were in the order: amines > carboxylic acids > alcohols > ketones. The crown ether PZ detector also exhibited good sensitivity for some heavy metal ions and the frequency shifts were in the order: Cr³⁺ » Pb²⁺ > Co²⁺ > Cd²⁺ > Ni²⁺ > Cu²⁺. The crown ether coated piezo electric crystal LC detector demonstrated low detection limits for various polar organic molecules, e.g., 6.0 × 10^?5 M for propylamine, and metal ions, e.g., 2.9 × 10^?5 M (1.8 ppm) for Cu²⁺; the crown ether PZ detector also gave good reproducibility when re used. A quite sensitive electrochemical quartz crystal microbalance (EQCM) detection system was also set‐up for detecting trace heavy metal ions in solutions. The variation in frequency of the PZ crystal and the diffusion current were observed simultaneously after the reduction in heavy metal ions such as Cu²⁺ and Ni²⁺. The EQCM detection system exhibited fairly good sensitivity, e.g., 112 Hz/ppm for Cu²⁺ and a good detection limit, e.g., 0.13 ppm for Cu²⁺ ions. Comparison between EQCM and PZ detection systems was made and discussed.     

Multi‐gel casting apparatus for vertical polyacrylamide gels with in‐built solution flow system and liquid level detectors

PAGE is the most widely used technique for the separation and biochemical analysis of biomolecules. The ever growing field of proteomics and genomics necessitates the analysis of many proteins and nucleic acid samples to understand further about the structure and function of cells. Simultaneous analysis of multiple protein samples often requires casting of many PAGE gels. Several variants of multi‐gel casting/electrophoresis apparatuses are frequently used in research laboratories. Requirement of supplementary gels to match the growing demand for analyzing additional protein samples sometimes become a cause of concern. Available apparatuses are not amenable to and therefore, not recommended for any modification to accommodate additional gel casting units other than what is prescribed by the manufacturer. A novel apparatus is described here for casting multiple PAGE gels comprising four detachable components that provide enhanced practicability and performance of the apparatus. This newly modified apparatus promises to be a reliable source for making multiple gels in less time without hassle. Synchronized functioning of unique components broaden the possibilities of developing inexpensive, safe, and time‐saving multi‐gel casting apparatus. This apparatus can be easily fabricated and modified to accommodate desired number of gel casting units. The estimated cost (∼$300) for fabrication of the main apparatus is very competitive and effortless assembly procedure can be completed within ∼30 min.     

Rapid Detection of Staphylococcal Enterotoxin B by Two-Dimensional Molecularly Imprinted Film-Coated Quartz Crystal Microbalance

We fabricated a two-dimensional (2D) molecularly imprinted sol-gel thin film-coated quartz crystal microbalance (QCM) for the rapid detection of staphylococcal enterotoxin B (SEB) by combining organosilanes and the template protein SEB on the surface of piezoelectric quartz crystal (PQC) Au-electrode by in-situ immobilization. The detection process was monitored by the QCM's frequency shift (Δf). The working range of this method was 1.0 × 10^?1–1.0 × 10³ µg/mL. The detection limit was 6.1 ng/mL, which was lower than that of the PQC immunosensor, and the detection period was within 0.5 h. The reproducibility of the imprinted film-coated QCM was satisfactory due to no significant statistical difference (P > 0.05) in the rapid detection of SEB between intra- and inter-batch. The selectivity of the imprinted sol-gel film showed that it could discriminate the template molecule from its analogues and other guest molecules. Compared with immunochip, the imprinted film-coated QCM is more advantageous in terms of simplicity, rapidity, low cost, and sensitivity. Moreover, in real sample analysis, the recoveries of this method were 89.4–106.63%, which can be considered a favorable and applicable method for the rapid determination of SEB in real samples.     

压电晶体传感器阵列判别分析小分子脂肪醇蒸气

选用８个不同材料涂层压电石英晶体组成传感器阵列，所获频移数据用逐步判别（ＳＤＡ）法解析，对小分子脂肪醇类与非醇类溶剂蒸气用二类判别法分析，找到由少于８个传感器组成阵列可达最佳判别能力，训练集回测正确率平均为８４．８％，预测集识别正确率平均为８７．３％。此外，该阵列用于识别酒、饮料，结果较佳。     

表面温敏聚合物刷的原子力显微镜和石英晶体微天平研究

通过表面引发的原子转移自由基聚合在硅片表面制备了聚（N-异丙基丙烯酰胺）（PNIPAAm）聚合物刷。用原子力显微镜（AFM）分别研究了PNIPAAm的接枝动力学、温度和溶剂性质对厚度的影响以及PNIPAAm链与原子力针尖间的粘附力。结果表明,PNIPAAm链在硅片表面的生长具有很好的可控性。常温下厚度为33nm的PNIPAAm膜在水溶液中的增加到82.4nm;而在甲醇/水（v/v,1:1）溶液中,PNIPAAm分子链处于坍塌收缩状态,厚度降低为45nm;在55℃下干燥所得厚度则仅为22nm。力-距离测量结果表明,在溶液中,PNIPAAm链与原子力针尖之间的粘附力远小于在干态下的粘附力。用石英晶体微天平（QCM-D）对PNIPAAm的可逆相转变进行了研究,结果表明PNIPAAm分子链随温度变化的构象转变是发生在30-34℃之间的连续过程。     

Water Content of Hydrated Polymer Brushes Measured by an In Situ Combination of a Quartz Crystal Microbalance with Dissipation Monitoring and Spectroscopic Ellipsometry

Poly(methacryloyloxy ethyltrimethylammonium chloride) (PMETAC), poly(sulfopropylmethacrylate potassium salt), or poly(N‐isopropyl acrylamide) (PNIPAM) brushes are synthesized by means of the atom transfer radical polymerization technique from gold surfaces coated with a monolayer of the initiator ω‐mercaptoundecyl bromo isobutyrate. The brush growth is followed in situ and in real time by the combination of quartz crystal microbalance with dissipation technique (QCM‐D) and spectroscopic ellipsometry in a single device. The combination of QCM‐D and ellipsometry allows for the simultaneous determination of both the acoustic mass, m_acous, comprising the mass of the polymer and the solvent, and the optical mass, m_opt, which corresponds to the polymer mass alone. Brush hydration is calculated from the difference between the values obtained for m_acous and m_opt for each polymer synthesized. Brush hydration is then used to quantify the percentage of water released in the brush during collapse; a 30–40% release of water for PMETAC and PSPM brushes in 1 M NaCl and 80% for PNIPAM brushes when the temperature is increased to values above the lower critical solution temperature is observed.     

Glucose‐Sensitive QCM‐Sensors Via Direct Surface RAFT Polymerization

Thin, phenylboronic acid‐containing polymer coatings are potentially attractive sensory layers for a range of glucose monitoring systems. This contribution presents the synthesis and properties of glucose‐sensitive polymer brushes obtained via surface RAFT polymerization of 3‐methacrylamido phenylboronic acid (MAPBA). This synthetic strategy is attractive since it allows the controlled growth of PMAPBA brushes with film thicknesses of up to 20 nm via direct polymerization of MAPBA without the need for additional post‐polymerization modification or deprotection steps. QCM‐D sensor chips modified with a PMAPBA layer respond with a linear change in the shift of the fundamental resonance frequency over a range of physiologically relevant glucose concentrations and are insensitive toward the presence of fructose, thus validating the potential of these polymer brush films as glucose sensory thin coatings.

     

Towards Vaporized Molecular Discrimination: A Quartz Crystal Microbalance (QCM) Sensor System Using Cobalt‐Containing Mesoporous Graphitic Carbon

A recent study on nanoporous carbon based materials (J. Am. Chem. Soc.­ 2012 , 134, 2864) showed that the presence of abundant graphitized sp² carbon species in the frameworks led to higher affinity for aromatic hydrocarbons than their aliphatic analogues. Herein, improved understanding of the sensitive and selective detection of aromatic substances by using mesoporous carbon (MPC)‐based materials, combined with a quartz crystal microbalance (QCM) sensor system, was obtained. MPCs were synthesized by direct carbonization of mesoporous polymers prepared from resol through a soft templating approach with Pluronic F127. The carbon‐based frameworks can be graphitized through the addition of a cobalt source to the precursor solution, according to the catalytic activity of the cobalt nanoparticles formed during the carbonization process. From the Raman data, the degree of the graphitization was clearly increased by increasing the cobalt content and elevating the carbonization temperature. From a QCM study, it was proved that the highly graphitized MPCs exhibited a higher affinity for aromatic hydrocarbons than their aliphatic analogues. By increasing the degree of graphitization in the carbon‐based pore walls, the MPCs showed both larger adsorption uptake and faster sensor response towards toxic benzene and toluene vapors.     

Assessment of DNA Binding to Human Rad51 Protein by using Quartz Crystal Microbalance and Atomic Force Microscopy: Effects of ADP and BRC4‐28 Peptide Inhibitor

The interaction of human Rad51 protein (HsRad51) with single‐stranded deoxyribonucleic acid (ssDNA) was investigated by using quartz crystal microbalance (QCM) monitoring and atomic force microscopy (AFM) visualization. Gold surfaces for QCM and AFM were modified by electrografting of the in situ generated aryldiazonium salt from the sulfanilic acid to obtain the organic layer Au–ArSO₃H. The Au–ArSO₃H layer was activated by using a solution of PCl₅ in CH₂Cl₂ to give a Au–ArSO₂Cl layer. The modified surface was then used to immobilize long ssDNA molecules. The results obtained showed that the presence of adenosine diphosphate promotes the protein autoassociation rather than nucleation around DNA. In addition, when the BRC4‐28 peptide inhibitor was used, both QCM and AFM confirmed the inhibitory effect of BRC4‐28 toward HsRad51 autoassociation. Altogether these results show the suitability of this modified surface to investigate the kinetics and structure of DNA–protein interactions and for the screening of inhibitors.     

Electrochemical Quartz Crystal Microbalance Studies on the Codeposition of Dextran Sodium Sulfate with the Charge‐Transfer Complexes Generated During Electrooxidation of Benzidine Derivatives

The electrochemical quartz crystal microbalance (EQCM) technique was used to investigate the electrochemistry of three benzidine derivatives, o‐tolidine (o‐TD), 3,3′,5,5′‐tetramethyl‐benzidine (TMB) and o‐dianisidine (o‐DA), in Britton‐Robinson (B‐R) buffer solutions with and without coexisting dextran sodium sulfate (DSS), respectively. During the anodic potential sweep from 0.1 to 0.7 V vs. SCE in pH 5.0 B‐R buffer solution containing o‐TD, the EQCM frequency was decreased during the first‐step oxidation of o‐TD and then increased to some extent during its second‐step oxidation, implying that a poorly soluble charge‐transfer complex (CTC) was produced here as an oxidation intermediate, and its precipitation and then dissolution at the EQCM Au electrode decreased and then increased the frequency. The depth of the V‐shaped time‐dependent frequency response (?Δf_0V) to the redox switching of the CTC/o‐TD couple (0.1–0.37 V vs. SCE) was notably enhanced in the presence of DSS, being due to the formation of a mass‐enhanced CTC‐DSS adduct via electrostatic affinity. Similar phenomena were evident in the TMB system, but the CTC behavior was not observed during o‐DA oxidation in the absence of DSS, namely, the EQCM frequency kept decreasing all the time, due probably to the too high lability of the CTC from o‐DA oxidation, and the coexistence of DSS could well stabilize this CTC and turn on its CTC behavior. The o‐TD system showed the highest sensitivity to DSS and was thus examined in detail. The mechanism for the CTC‐DSS interaction is discussed from EQCM, FT‐IR and UV‐vis data. The CTC‐based EQCM determination of DSS, which is featured by a dynamically renewed surface of the detection electrode, was thus proposed, with a linear range from 0.002 to 1.6 μmol L^?1 and a detection limit down to 0.7 nmol L^?1 (o‐TD system).