Quartz Crystal Microbalance Sensor Surface Research Articles

Selective aptasensor for trinitrotoluene detection: Comparison of the detecting performances from liquid and vapor phases

In general, chromatographic and sensor analyses have been utilized for explosive detection. The main interest on those systems is to develop a method to selectively detect explosives at a single step as well as from vapor phase if possible. Moreover, on-site and real-time detection with portable systems is another challenge for the researchers. On the other hand, the detection of 2,4,6-trinitrotoluene (TNT) vapor at the crime scene, preferably before the explosion is highly demanded in order to prevent the negative effects of terrorism and to ensure the safety of the civilian population. In this study, initially, Quartz Crystal Microbalance (QCM) sensor was prepared for real-time monitoring of TNT in aqueous solution, through the attachment of TNT peptide aptamer on the gold surface of QCM sensor. Secondly, after providing optimum conditions, TNT detection was investigated even from vapor phase through the QCM aptasensor. According to results, the selectivity coefficient of QCM-based aptasensor was calculated as 6.78 for TNT in respect to DNT whereas that was calculated as 9.02 for TNT in respect to TNB. In addition, the evaluation of the reusability and storage stability emphasized that the sensor could be used repeatedly without significant reduction in dissipation (∆D) values. The linearity coefficient (R2) was found to be 0.9965. The limit of detection (LOD) and the limit of quantitation (LOQ) were determined as 0.0238 and 0.0739 nM, respectively. The studies demonstrated that the portable QCM sensor decorated with the aptamer selective for TNT molecules could be classified as a promising alternative, selective, cost-friendly, easy-to-prepare, ready-to-use, and applicable for on-site and real-time explosive measurements (even from vapor phase).

A Novel Peptide-Based Detection of SARS-CoV-2 Antibodies.

The need for rapidly developed diagnostic tests has gained significant attention after the recent pandemic. Production of neutralizing antibodies for vaccine development or antibodies to be used in diagnostic tests usually require the usage of recombinant proteins representing the infectious agent. However, peptides that can mimic these recombinant proteins may be rapidly utilized, especially in emergencies such as the recent outbreak. Here, we report two peptides that mimic the receptor binding domain of the spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and investigate their binding behavior against the corresponding human immunoglobulin G and immunoglobulin M (IgG and IgM) antibodies in a clinical sample using a quartz crystal microbalance (QCM) sensor. These peptides were immobilized on a QCM sensor surface, and their binding behavior was studied against a clinical serum sample that was previously determined to be IgG and IgM-positive. It was determined that designed peptides bind to SARS-CoV-2 antibodies in a clinical sample. These peptides might be useful for the detection of SARS-CoV-2 antibodies using different methods such as enzyme-linked immunosorbent assay (ELISA) or lateral flow assays. A similar platform might prove to be useful for the detection and development of antibodies in other infections.

High-speed nanoscale tribology enabled by combined QCM/AFM

Forming a fundamental understanding of tribological processes on the atomic scale has the potential to revolutionize the control of friction and wear in macroscopic mechanical systems. On the other hand, methods such as atomic force microscopy (AFM) that provide nanoscale spatial resolution are severely limited in terms of scanning speed when compared with macroscopic mechanical processes, leading to a “speed gap” between fundamental and applied tribology that spans several orders of magnitude. Here, we propose a new method combining AFM experiments with simultaneous quartz crystal microbalance (QCM) measurements for high-speed nanoscale tribology. In particular, scanning speed and vibration amplitude are controlled by QCM whereas normal loads are controlled by AFM. Complementary data are simultaneously recorded in the form of nanoscale, two-dimensional maps of frequency shifts and lateral forces provided by the QCM and AFM, respectively. Proof-of-principle results are presented on a gold-coated QCM sensor surface patterned with a graphene array, whereby stick and partial slip regimes are observed as a function of sliding speed.

In situ discrimination of polymorphs and phase transformation of sulfamerazine using quartz crystal microbalance

A novel strategy utilizing the quartz crystal microbalance (QCM) was developed for the in situ discrimination of polymorphic nucleation (form-I and form-II) and phase transformation of sulfamerazine (SMZ) in cooling crystallization. According to Ostwald's rule of stages, metastable form-I of SMZ is first nucleated and then shifted to stable form-II by solution-mediated phase transformation. Through surface modification with the self-assembled monolayer technique of a functional group, QCM distinctively detects the formation of the two polymorphs. The results indicated that –NH2 (among the several functional groups tested) selectively accommodated stable form-II on the QCM sensor's surface and completely prevented the adsorption of metastable form-I on the surface. Therefore, the–NH2-terminated QCM detected the formation of form-I only using the solution viscosity variation on the surface. However, it monitored the nucleation and growth of form-II via the solid mass change on the surface during the phase transformation of form-I to form-II. This strategy suggests a new and precise solution for in situ discrimination of SMZ polymorphs and their phase transformation.

Vapor Sorption-Desorption Phenomena of HD and GB Simulants from Polyurethane Thin Films on Aluminum Oxide via a Quartz Crystal Microbalance.

Protection and decontamination of surfaces after exposure to chemical warfare agents (CWAs) are of considerable interest to the homeland defense and battlespace operation communities. In this work, polyurethane was spin-coated onto aluminum oxide quartz crystal microbalance (QCM) sensors. Polyurethane film thickness was varied by altering the concentration of the polymer/chloroform solution used for spin-coating. Atomic force microscopy confirmed the formation of smooth, homogeneous films on the QCM sensor surface. Aluminum oxide QCM sensors coated with polyurethane were exposed to saturated vapors of dichloropentane (DCP), a mustard gas (HD) simulant, and dimethyl methylphosphonate (DMMP), a sarin gas (GB) simulant, and the mass uptake, diffusion coefficient, volume fraction, and partition coefficient of the simulant in the film were determined from QCM data. Results showed that both DCP and DMMP readily sorbed into the films although the mass uptake of DCP was greater than that of DMMP owing to DCP’s higher vapor pressure. Additionally, the CWA simulant uptake increased with polyurethane film thickness. Sorption diffusion coefficients were 1 × 10–13 cm2/s and 1 × 10–12 cm2/s for DCP and DMMP vapor, respectively. Simulant desorption was also measured and showed that some DMMP remained in the film/substrate system, while DCP sorption was fully reversible. Reversible desorption for both CWA simulants was relatively quick and independent over the range of film thicknesses studied, with average desorption diffusion coefficients of 2 × 10–9 cm2/s and 1 × 10–11 cm2/s for DCP and DMMP, respectively. Collectively, this study is expected to inform protection and decontamination strategies of equipment and structures upon exposure to CWAs.

Uniform Mass Sensitivity Distribution of Elliptically Designed Electrodes Based on a Quartz Crystal Microbalance.

Uniformization of mass sensitivity distribution is conducive to the application of the quartz crystal microbalance (QCM) in some fields. However, the sensitivity of the QCM sensor surface perpendicular to the displacement direction is higher that of the displacement direction in the mass sensitivity distribution of ring and double-ring QCMs, which leads to poor reproducibility of the sensor. Considering the effect of the electrode structure on the mass sensitivity distribution, we found that for ring- and double-ring-type QCMs, when the elliptical single ring and double-ring electrode structures are combined, an approximately uniform mass sensitivity can be obtained in all directions. Therefore, this study proposes the elliptical single-ring and elliptical double-ring electrode structure design. Through theoretical calculations and three-dimensional finite element analysis verification, a systematic investigation is carried out to quantify the effect of the ratio of the minor axis to the major axis of the elliptical electrode on the mass sensitivity distribution in different directions, and the optimal ratio is found to be 0.8. Comparing the mass sensitivity of the new type of electrodes and the original electrodes, the result shows that the mass sensitivity distribution of the elliptical double-ring electrode structure is more uniform. Hence, these specially designed electrodes are conducive to improving the repeatability.

Construction of a Self-Assembled Polyelectrolyte/Graphene Oxide Multilayer Film and Its Interaction with Metal Ions.

In this study, a composite multilayer film onto gold was constructed from two charged building blocks, i.e., negatively charged graphene oxide (GO) and a branched polycation (polyethylenimine, PEI) via layer-by-layer (LbL) self-assembly technology, and this process was monitored in situ with quartz crystal microbalance (QCM) under different experimental conditions. This included the differences in frequency (Δf) as well as the changes in dissipation to yield information on the absorbed mass and viscoelastic properties of the formed PEI/GO multilayer films. The experimental conditions were optimized to obtain a high amount of the adsorbed mass of the self-assembled multilayer film. The surface morphology of the PEI/GO multilayer film onto gold was studied with atomic force microscopy (AFM). It was found that the positively charged PEI chains were combined with the oppositely charged GO to form an assembled film on the QCM sensor surface, in a wrapped and curled fashion. Raman and UV-vis spectra also showed that the intensities of the GO-characteristic signals are almost linearly related to the layer number. To explore the films for their use in divalent ion detection, the frequency response of the PEI/GO multilayer-modified QCM sensor to the exposure of aqueous solutions solution of Cu2+, Ca2+, Zn2+, and Sn2+ was further studied using QCM. Based on the Sauerbrey equation and the weight of different ions, the number of metal ions adsorbed per unit area on the surface of QCM sensors was calculated. For metal ion concentrations of 40 ppm, the adsorption capacities per unit area of Cu2+, Zn2+, Sn2+, and Ca2+ were found to be 1.7, 3.2, 0.7, and 4.9 nmol/cm2, respectively. Thus, in terms of the number of adsorbed ions per unit area, the QCM sensor modified by PEI/GO multilayer film shows the largest adsorption capacity of Ca2+. This can be rationalized by the relative hydration energies.

Construction of Self-Assembled Polyelectrolyte/Cationic Microgel Multilayers and Their Interaction with Anionic Dyes Using Quartz Crystal Microbalance and Atomic Force Microscopy.

This study aimed to reveal the interaction between self-assembled multilayers and dye molecules in the environment, which is closely related to the multilayers’ stable performance and service life. In this work, the pH-responsive poly (N-isopropylacrylamide-co-2-(dimethylamino) ethyl methacrylate) microgels were prepared by free-radical copolymerization and self-assembled with sodium alginate (SA) into multilayers by the layer-by-layer deposition method. Quartz crystal microbalance (QCM) and atomic force microscopy (AFM) results confirmed the construction of multilayers and the absorbed mass, resulting in a decrease in the frequency shift of the QCM sensor and the deposition of microgel particles on its surface. The interaction between the self-assembled SA/microgel multilayers and anionic dyes in the aqueous solution was further investigated by QCM, and it was found that the electrostatic attraction between dyes and microgels deposited on the QCM sensor surface was much larger than that of the microgels with SA in multilayers, leading to the release of the microgels from the self-assembled structure and a mass loss ratio of 27.6%. AFM observation of the multilayer morphology exposed to dyes showed that 29% of the microgels was peeled off, and the corresponding microgel imprints were generated on the surface. In contrast, the shape and size of the remaining self-assembled microgel particles did not change.

Real-time and selective recognition of erythromycin by self-assembly of calix[4]arene on QCM sensor

This paper describes the synthesis of an amino morpholine-based the new schiff base calix[4]arene (compound 5), it's coating on Quartz Crystal Microbalance (QCM) crystal as a self-assembled monolayer (SAM), and real-time detection of erythromycin (ERY) in aqueous media. The characterization of the QCM sensor has been succeeded with atomic force microscopy and contact angle measurements. Initial experiments revealed that the frequency response decreased quickly as expected and reached equilibrium within 5 min which means that there was a good interaction between the compound 5 coated QCM sensor surface and ERY molecules. The QCM sensor showed a linear response towards ERY solutions in different concentrations ranging from 10 to 200 μM, with the sensitivity (S) and limit of detection (LOD) being 0.66 Hz/μM and 4.80 μM, respectively. Furthermore, the adsorption behavior and mechanism of ERY onto the QCM sensor were applied for this sensing system and the adsorption data exhibited a good correlation with the Langmuir adsorption isotherm in terms of R2 and Δmmax. The QCM sensor was shown outstanding selective performance to ERY among some biologic molecules such as amino acid, drug, hormone, vitamin. Thus, real-time, sensitive, selective and effective recognition of ERY was performed by a calixarene derivative coated QCM sensor.

Strategic Approaches for Highly Selective and Sensitive Detection of Hg2+ Ion Using Mass Sensitive Sensors.

Here we present a quartz crystal microbalance (QCM) sensor for the highly selective and sensitive detection of Hg2+ ion, a toxic chemical species and a hazardous environmental contaminant. Hg2+ ion can be quantitatively measured based on changes in the resonance frequency of QCM following mass changes on the QCM sensor surface. The high selectivity for Hg2+ ion in this study can be obtained using a thymine-Hg2+-thymine pair, which is more stable than the adenine-thymine base pair in DNA. On the other hand, gold nanoparticles (AuNPs) and their size-enhancement techniques were used to amplify the QCM signals to increase the sensitivity for Hg2+ ion. With this strategic approach, the proposed QCM sensor can be used to quantitatively analyze Hg2+ ion with high selectivity and sensitivity. The detection limit was as low as 98.7 pM. The sensor failed to work with other metal ions at concentrations 1000-times higher than that of the Hg2+ ion. Finally, the recovery does not exceed 10% of the original value for the detection of Hg2+ ion in tap and bottled water. The results indicate acceptable accuracy and precision for practical applications.

Rapid and Sensitive Detection of Campylobacter jejuni in Poultry Products Using a Nanoparticle-Based Piezoelectric Immunosensor Integrated with Magnetic Immunoseparation

Campylobacter jejuni is one of the leading causes of foodborne human gastrointestinal diseases. Poultry and poultry products have been identified as the major transmission routes to humans for this pathogenic bacterium. The objective of this research was to develop a rapid and sensitive immunosensor for detection of C. jejuni in poultry products on the basis of a quartz crystal microbalance (QCM) using magnetic nanobeads (MNBs) for separation of target pathogen and gold nanoparticles for amplification of the measurement. A QCM sensor in a flow cell was prepared by immobilizing the mouse anti- C. jejuni monoclonal antibody (mAb1) on the sensor surface to specifically capture C. jejuni. Rabbit anti- C. jejuni polyclonal antibody (pAb1) was conjugated with MNBs to capture and separate C. jejuni from food matrices. MNB-pAb1- C. jejuni complexes were injected into the flow cell to bind with the mAb1 immobilized on the QCM sensor surface. Goat anti-rabbit immunoglobulin G polyclonal antibody conjugated with gold nanoparticles was injected into the flow cell to bind with pAb1 on MNBs. Finally, resonant frequency was measured with a QCM analyzer, and the change in resonant frequency was correlated to the cell number of C. jejuni. The specificity of this immunosensor was confirmed with different strains of Campylobacter, Salmonella, and other foodborne pathogens commonly colonized in the broiler gastrointestinal tract. Samples of broiler carcass wash and ground turkey were spiked with C. jejuni at different concentrations for use in tests. Results showed that the QCM immunosensor could rapidly detect C. jejuni in poultry products, with a detection limit of 20 to 30 CFU/mL without preenrichment, and a total detection time of less than 30 min. Characteristics of C. jejuni captured by the antibody immobilized on the surface of the QCM sensor were visualized by using atomic force microscopy. This highly adaptive and flexible method could provide the poultry industry a more rapid, sensitive, and effective method for detection of major foodborne pathogens in poultry products.

Development of MIP-based QCM Sensors for Determination of Hyaluronic Acid (HA)

I n this study, quartz crystal microbalance (QCM) based recognition systems have been developed for the determination of hyaluronic acid (HA). For this purpose, firstly; N-methacryloyl-l-tyrosine (MAT), MAT-DGlucuronic acid (MAT-D-GA) and MAT-Cu(II)-D-Glucuronic acid (MAT-Cu(II)-D-GA) pre-organized monomers have been synthesized, and characterized. Then, D-glucuronic acid active sites of HA biomacromolecule have been imprinted on QCM sensor surface to create HA selective binding sites. In the last step, the binding interactions, usabilities in recognition and determination of prepared sensors have been investigated.

A quartz crystal microbalance-based biosensor for enzymatic detection of hemoglobin A1c in whole blood

Abstract Here we present a quartz crystal microbalance (QCM) biosensor for enzymatic detection of hemoglobin A1c (HbA1c). It shows average plasma glucose concentration readings over the prior three months. HbA1c can be quantitatively measured based on changes of resonance frequency of QCM following mass changes on QCM sensor surface. These mass changes were caused by size enlargement of conjugated gold nanoparticle with thiol-terminated SAMs on the sensor surface due to gold staining by hydrogen peroxide (H2O2) generated from enzymatic HbA1c assay. Finally, we investigated sensor responses due to mass changes on various concentrations of applied H2O2. We also demonstrated its capability for analyzing HbA1c in whole blood sample with enzymatic assay. Our results showed that the proposed QCM biosensor could quantitatively analyze HbA1c with a detection limit of 0.147% HbA1c with respect to hemoglobin and a coefficient variation of less than 10%.

Ultrasensitive Detection of DNA and Ramos Cell Using In Situ Selective Crystallization Based Quartz Crystal Microbalance.

Herein we introduce the first successful assay of biomolecule by in situ selective crystallization based quartz crystal microbalance (QCM). Selective crystallization of CaCO3 on QCM sensor surface was utilized as an efficient mass amplification strategy and enhanced the sensitivity of QCM significantly. High specificity is guaranteed by the cooperation of two functional groups: -N(CH3)3 and -COOH. Passivation of sensor surface is realized by self-assembly of -N(CH3)3, which effectively inhibited the nonspecific crystallization. The DNA target is detected through hybridization of probe DNA labeled with -COOH, which can effectively promot the in situ surface crystallization of CaCO3. The concentration of target DNA is reflected by the frequency shift of QCM which is directly induced by the surface crystallization. The selective crystallization based QCM platform is simple, straightforward, high sensitive, and high specific. We demonstrate the excellent LOD (2 aM DNA) and a linear range of 10aM to 1 nM for DNA. Detection of Ramos cells are also realized with a LOD of five cells and a linear range of 5-6000 cells.

Improving the binding efficiency of quartz crystal microbalance biosensors by applying the electrothermal effect.

A quartz crystal microbalance (QCM) serving as a biosensor to detect the target biomolecules (analytes) often suffers from the time consuming process, especially in the case of diffusion-limited reaction. In this experimental work, we modify the reaction chamber of a conventional QCM by integrating into the multi-microelectrodes to produce electrothermal vortex flow which can efficiently drive the analytes moving toward the sensor surface, where the analytes were captured by the immobilized ligands. The microelectrodes are placed on the top surface of the chamber opposite to the sensor, which is located on the bottom of the chamber. Besides, the height of reaction chamber is reduced to assure that the suspended analytes in the fluid can be effectively drived to the sensor surface by induced electrothermal vortex flow, and also the sample costs are saved. A series of frequency shift measurements associated with the adding mass due to the specific binding of the analytes in the fluid flow and the immobilized ligands on the QCM sensor surface are performed with or without applying electrothermal effect (ETE). The experimental results show that electrothermal vortex flow does effectively accelerate the specific binding and make the frequency shift measurement more sensible. In addition, the images of the binding surfaces of the sensors with or without applying electrothermal effect are taken through the scanning electron microscopy. By comparing the images, it also clearly indicates that ETE does raise the specific binding of the analytes and ligands and efficiently improves the performance of the QCM sensor.

Penentuan Kensentrasi Optimum Anti Protein Spesifik Susu Sapi 208 kDa pada Sensor QCM

The purpose of the research is to detect optimum concentration of immobilization of anti protein cow’s milk with 208 kDa molecular weight’s (anti PSS 208 kDa) by utilizing QCm (Quartz Crystal Microbalance) sensor. The purpose of research is to detect optimum concentration of immobilization of specific anti protein cow’s milk with 208 kDa molecular weight’s (anti PSS 208 kDa) by utilizing QCM ( Quartz Crystal Microbalance) sensor. QCM sensor had been coated by polystiren solution of 5% which is heated until 200 ◦C. During measurement, QCM sensor place on data accuisition and QCM-Box measurement. 30 µL Anti PSS 208 kDa with concentration varied between 200 mg/L up to 1400 mg/L was dropped to QCM sensors. Frequency changes were recorded as a function of concentration of anti PSS 208 kDa. The frequency changes due to presence of anti PSS 208 kDa deposited on the surface of QCM sensor were not spontaneous, but takes time to reach steady state. As the concentration of anti PSS 208 kDa increased, so is the frequency change until it reaches saturation point at 1000 mg/L. The mass percentage of anti PSS 208 kDa deposited on QCM sensor surface is decreased with increasing anti PSS 208 kDa concentration. Therefore optimum immobilization concentration of anti PSS 208 kDa is define on frequency changes at first saturation point, that is at 1000 mg/L concentration namely 267 ± 5 Hz

Modelling of blood component flexibility using quartz crystal microbalance

Quartz crystal microbalance (QCM) is a sensitive technique for real-time monitoring of cell adsorption, aggregation and cell-to-surface interaction processes. However, cell adhesion time courses are usually considered as merely qualitative, being presented in terms of QCM resonant frequency shift and/or changes in the dissipation parameter, the precise physical meanings of which are not derived. In the present study, a model of cell adhesion to the QCM sensor surface was proposed. The main output parameter of the model is the rigid mass density, Mr, being related to QCM resonant frequency and dissipation with a simple expression. From this, it can be determined that Mr is the mass density of the layer formed by all directly adhered parts of the cell, being rigidly coupled to the sensor surface. We postulate that the Mr(t) value is proportional to the number of cells adhered by the time t, and that the coefficient of this proportionality is strongly dependent on cell-to-surface interaction forces.

Atrazine-Based Self-Assembled Monolayers and Their Interaction with Anti-Atrazine Antibody: Building of an Immunosensor

As a part of our objective to build an immunosensor for the detection of the pesticide atrazine (ATZ) in environmental samples, we studied the self-assembling process of the disulfide derivative of the pesticide atrazine on a gold substrate. Atrazine-based self-assembled monolayers were characterized by ellipsometry, scanning tunneling microscopy, polarization-modulation infrared reflection-absorption spectroscopy (PM IRRAS), X-ray photoelectron spectroscopy and quartz crystal microbalance (QCM) measurements. Two different time constants for the adsorption process were observed, depending on the experimental method used. The QCM data reflect adsorption kinetics of the original disulfide compound, whereas ellipsometry and ex situ PM IRRAS refer to the formation of thiolate (ATZS) monolayers. In situ QCM data demonstrated the suitability of such monolayers for the detection of atrazine in aqueous samples. Exposure of the ATZS sensing surface to an anti-atrazine antibody (anti-ATZ IgG) resulted in complete coverage of the surface by antibody, whereas approximately half of the antibody molecules were displaced from the QCM sensor surface by further addition of atrazine into the solution.

New synthesis method for 4-MAPBA monomer and using for the recognition of IgM and mannose with MIP-based QCM sensors

Quartz crystal microbalance (QCM) sensors coated with molecularly imprinted polymers (MIP) have been developed for the recognition of immunoglobulin M (IgM) and mannose. In this method, methacryloylamidophenylboronic acid (MAPBA) was used as a monomer and mannose was used as a template. For this purpose, initially, QCM electrodes were modified with 2-propene-1-thiol to form mannose-binding regions on the QCM sensor surface. In the second step, the methacryloylamidophenylboronic acid-mannose [MAPBA-mannose], pre-organized monomer system, was prepared using the MAPBA monomer. Then, a molecularly imprinted film was coated on to the QCM electrode surface under UV light using ethylene glycol dimethacrylate (EDMA), and azobisisobutyronitrile (AIBN) as a cross-linking agent and an initiator, respectively. The mannose can be simultaneously bound to MAPBA and fitted into the shape-selective cavities. The binding affinity of the mannose-imprinted sensors was investigated using the Langmuir isotherm. The mannose-imprinted QCM electrodes have shown homogeneous binding sites for mannose (K(a): 3.3 × 10(4) M(-1)) and heterogeneous binding sites for IgM (K(a1): 1.0 × 10(4) M(-1); K(a2): 3.3 × 10(3) M(-1)).

QCM Aptasensor for Rapid and Specific Detection of Avian Influenza Virus

There has been a need for rapid detection of Avian Influenza virus (AIV) H5N1 due to it being a potential pandemic threat. Most of the current methods, including culture isolation and PCR, are very sensitive and specific but require specialized laboratories and trained personnel in order to complete the tests and are time-consuming. The goal of this study was to design a biosensor that would be able to rapidly detect AIV H5N1 using aptamers as biosensing material and a quartz crystal microbalance (QCM) for transducing method. Specific DNA aptamers against AIV H5N1 were immobilized, through biotin and streptavidin conjugation, onto the gold surface of QCM sensor to capture the target virus. Magnetic nanobeads (150 nm in diameter) were then added as amplifiers considering its large surface/volume ratio which allows for faster movement and a higher target molecule binding rate. The result showed that the captured AIV caused frequency change, and more change was observed when the AIV concentration increased. The nanobead amplification was effective at the lower concentrations of AIV, however, it was not significant when the AIV concentration was 1 HA or higher. The detection limit of the aptasensor was 1 HAU with a detection time of 1 h. The capture of the target virus on to the surface of QCM sensor and the binding of magnetic nanobeads with the virus was confirmed with electron microscopy. Aptamers have unlimited shelf life and are temperature stable which allows this aptasensor to give much more consistent results specifically for in field applications.