Vapor Sorption–Desorption Phenomena of HD and GB Simulants from Polyurethane Thin Films on Aluminum Oxide via a Quartz Crystal Microbalance
Ontology highlight
ABSTRACT:
SUBMITTER: Kittle J
PROVIDER: S-EPMC9260914 | biostudies-literature | 2022 Jun
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:There is little research on using the quartz crystal microbalance (QCM) with adsorbing viscoelastic fluids. These fluids are widely encountered but often difficult to study as many are opaque and highly viscous. Since the QCM does not involve any scattering or reflection of input radiation, it has the potential to study these complex fluids to determine the relative viscoelasticity of the bulk fluid and surface adsorption of active species onto different substrates. In the current study, both Newtonian (sucrose) and viscoelastic (sodium polystyrene sulfonate (NaPSS)) fluids were introduced into the QCM, and the sensor responses were compared. QCM responses of Newtonian sucrose solutions matched the Kanazawa and Gordon model (KG model), as expected. The QCM responses with viscoelastic NaPSS solutions were well below those described by the KG model. A viscoelastic model was used to determine the fluid viscosity and shear modulus at a very high frequency. It was found that the viscosity of NaPSS did not change much compared with low-frequency rheometer measurements, but a significant increase in the shear modulus of several orders of magnitude was found at the QCM frequencies. Modifying the KG model frequency shifts by multiplying by the QCM shear wave decay length ratio, X = δV/δN, we were able to match the measured QCM values in viscoelastic NaPSS solutions. The QCM dissipation values for NaPSS were matched in a similar way by multiplying the KG model by X 1/3. By changing the QCM sensor from silica (no NaPSS adsorption) to alumina (NaPSS adsorption), it was shown that the adsorption isotherm of NaPSS on alumina could be recovered and fitted with a Langmuir isotherm despite the frequency response being only a small fraction of the total measured QCM signal.
| S-EPMC7482089 | biostudies-literature
Project description:Extracellular vesicle (EV) quantification is a procedure through which the biomedical potential of EVs can be used and their biological function can be understood. The number of EVs isolated from cell culture media depends on the cell status and is especially important in studies on cell-to-cell signaling, disease modeling, drug development, etc. Currently, the methods that can be used to quantify isolated EVs are sparse, and each have limitations. In this report, we introduce the application of a quartz crystal microbalance (QCM) as a biosensor for quantifying EVs in a small drop of volatile solvent after it evaporates and leaves desiccated EVs on the surface of the quartz crystal. The shifts in the crystal's resonant frequency were found to obey Sauerbrey's relation for EV quantities up to 6 × 107, and it was determined that the biosensors could resolve samples that differ by at least 2.7 × 105 EVs. A ring-shaped pattern enriched in EVs after the samples had dried on the quartz crystal is also reported and discussed. QCM technology is highly sensitive and only requires small sample volumes and is significantly less costly compared with the approaches that are currently used for EV quantification.
| S-EPMC9221410 | biostudies-literature
Project description:Due to the influence of liquid load, the equivalent resistance of in-liquid quartz crystal microbalance (QCM) increases sharply, and the quality factor and resonant frequency decreases. We found that the change in the resonant frequency of in-liquid QCM consisted of two parts: besides the frequency changes due to the mass and viscous load (which could be equivalent to motional inductance), the second part of frequency change was caused by the increase of motional resistance. The theoretical calculation and simulation proved that the increases of QCM motional resistance may indeed cause the decreases of resonant frequency, and revealed that the existence of static capacitance was the root cause of this frequency change. The second part of frequency change (due to the increases of motional resistance) was difficult to measure accurately, and may cause great error for in-liquid QCM applications. A technical method to reduce the interference caused by this effect is presented. The study contributes to the accurate determination of the frequency and amplitude change of in-liquid QCM caused by liquid load, which is significant for the QCM applications in the liquid phase.
| S-EPMC5539828 | biostudies-other
Project description:Rapid and accurate serological analysis of SARS-CoV-2 antibodies is important for assessing immune protection from vaccination or infection of individuals and for projecting virus spread within a population. The quartz crystal microbalance (QCM) is a label-free flow-based sensor platform that offers an opportunity to detect the binding of a fluid-phase ligand to an immobilized target molecule in real time. A QCM-based assay was developed for the detection of SARS-CoV-2 antibody binding and evaluated for assay reproducibility. The assay was cross-compared to the Roche electrochemiluminescence assay (ECLIA) Elecsys® Anti-SARS-CoV-2 serology test kit and YHLO's chemiluminescence immunoassay (CLIA). The day-to-day reproducibility of the assay had a correlation of r2 = 0.99, p < 0.001. The assay linearity was r2 = 0.96, p < 0.001, for dilution in both serum and buffer. In the cross-comparison analysis of 119 human serum samples, 59 were positive in the Roche, 52 in the YHLO, and 48 in the QCM immunoassay. Despite differences in the detection method and antigen used for antibody capture, there was good coherence between the assays, 80-100% for positive and 96-100% for negative test results. In summation, the QCM-based SARS-CoV-2 IgG immunoassay showed high reproducibility and linearity, along with good coherence with the ELISA-based assays. Still, factors including antibody titer and antigen-binding affinity may differentially affect the various assays' responses.
| S-EPMC10705953 | biostudies-literature
Project description:The skin secretions of Australian tree frogs are rich in peptides with potential antimicrobial activity. They interrupt bacterial cell membranes, although precisely how and whether all peptides have the same mechanism is not known. The interactions of three of these peptides-aurein 1.2, maculatin 1.1, and caerin 1.1 with supported phospholipid bilayers-are examined here using quartz crystal microbalance and atomic force microscopy. These approaches enabled us to reveal variations in material structure and density as a function of distance from the sensor surface when comparing mass sensorgrams over a range of harmonics of the natural resonance of the sensor crystal and hence obtain for the first time to our knowledge a mechanistic assessment of membrane disruption. We found that caerin inserted into the bilayer in a transmembrane manner, regardless of concentration and phospholipid composition consistent with a pore-forming mechanism. In contrast, maculatin and aurein interacted with membranes in a concentration-dependent manner. At low concentrations (<5 microM), maculatin exhibited transmembrane incorporation whereas aurein was limited to surface association. Upon reaching a threshold value of concentration, both peptides lysed the membrane. In the case of maculatin, the lysis progressed in a slow, concentration-dependent manner, forming mixed micelles, as shown by atomic force microscopy imaging. Aurein-induced lysis proceeded to a sudden disruption, which is consistent with the "carpet" mechanism. Both maculatin and aurein exhibit specificity toward phospholipids and thus have potential as candidates as antimicrobial drugs.
| S-EPMC2084233 | biostudies-literature
Project description:Microliter volumes are used in electrochemical detection and preconcentration of radionuclides to reduce the dose received by researchers and equipment. Unfortunately, there is a lack of analysis of radionuclides with coupled electrochemical techniques and microliter volume reactors. The goals of this work are 1) to develop a miniaturized micro-electrochemical quartz crystal microbalance (µeQCM) reactor for use in small volume (50-200 µL) electrogravimetric experiments and 2) to use this reactor to characterize the preconcentration of neptunium on carbon electrodes via electroprecipitation. We successfully deposited neptunium in the new µeQCM reactor and verified its operation. We found that preconcentration of neptunium on carbon coated electrodes was possible by chronoamperometry at -1.6 VAg/AgCl. The mass shift of the resulting precipitate was indicative of the amount of neptunium on the electrode, although the correlation between the mass increase and activity of the preconcentrated material was not linear. Neptunium precipitate reduced electron transfer to the solution as evidenced by the increase in charge transfer resistance compared to bare electrodes.
| S-EPMC7323927 | biostudies-literature
Project description:Quantifying cellular behaviour by motility and morphology changes is increasingly important in formulating an understanding of fundamental physiological phenomena and cellular mechanisms of disease. However, cells are complex biological units, which often respond to external environmental factors by manifesting subtle responses that may be difficult to interpret using conventional biophysical measurements. This paper describes the adaptation of the quartz crystal microbalance (QCM) to monitor neuroblastoma cells undergoing environmental stress wherein the frequency stability of the device can be correlated to changes in cellular state. By employing time domain analysis of the resulting frequency fluctuations, it is possible to study the variations in cellular motility and distinguish between different cell states induced by applied external heat stress. The changes in the frequency fluctuation data are correlated to phenotypical physical response recorded using optical microscopy under identical conditions of environmental stress. This technique, by probing the associated biomechanical noise, paves the way for its use in monitoring cell activity, and intrinsic motility and morphology changes, as well as the modulation resulting from the action of drugs, toxins and environmental stress.
| S-EPMC4424671 | biostudies-literature
Project description:Glomalin is a soil protein resembling heat shock protein (HSP) 60 and exerting high affinity to metals, causing retention of water in the environment and improving mechanical stability of soil. Currently, glomalin is determined in the soil or other samples by combination of autoclaving extraction and total protein determination typically by the Bradford method. In this paper, a piezoelectric biosensor was prepared to determine glomalin in a label-free measurement. The biosensor contained antibodies immobilized on quartz crystal microbalance (QCM), and the recognition layer was stabilized by iron oxide nanoparticles. The assay was tested on real soil samples and compared with the standard Bradford assay. Limit of detection of the assay was equal to 2.4?µg/g for a soil extract with a volume of 50?µl. The assay takes approximately half of an hour and was fully correlated to the Bradford assay. The biosensor had significant advantages than the other methods: it worked in a label-free mode and was fully applicable for practical samples.
| S-EPMC7481945 | biostudies-literature
Project description:Exosomes are endocytic lipid-membrane bound bodies with the potential to be used as biomarkers in cancer and neurodegenerative disease. The limitations and scarcity of current exosome characterization approaches have led to a growing demand for translational techniques, capable of determining their molecular composition and physical properties in physiological fluids. Here, we investigate label-free immunosensing, using a quartz crystal microbalance with dissipation monitoring (QCM-D), to detect exosomes by exploiting their surface protein profile. Exosomes expressing the transmembrane protein CD63 were isolated by size-exclusion chromatography from cell culture media. QCM-D sensors functionalized with anti-CD63 antibodies formed a direct immunoassay toward CD63-positive exosomes in 75% v/v serum, exhibiting a limit-of-detection of 2.9 × 108 and 1.4 × 108 exosome sized particles (ESPs)/mL for frequency and dissipation response, respectively, i.e., clinically relevant concentrations. Our proof-of-concept findings support the adoption of dual-mode acoustic analysis of exosomes, leveraging both frequency and dissipation monitoring for use in bioanalytical characterization.
| S-EPMC7145312 | biostudies-literature
Project description:Laboratory studies have shown that photolytic mass loss can be a significant sink for secondary organic aerosol (SOA). Here, we use a quartz crystal microbalance to measure mass loss of Suwannee River Humic Acid (SRHA) and Suwannee River Fulvic Acid (SRFA), surrogates for SOA, exposed to 254, 300, and 405 nm radiation over the course of 24 h. We find that the photolytic mass loss rates of these materials are comparable to those for laboratory-generated limonene and toluene SOA material from the study of Baboomian et al, ACS Earth Space Chem. 2020, 4, 1078. Scaling our results to ambient conditions, we estimate that humic substances in aerosols can lose as much as 8% by mass in the first day of exposure in the atmosphere, equivalent to 0.025% of J NO2 , the photolysis rate of nitrogen dioxide. By using zero air instead of nitrogen, we also find that the presence of oxygen accelerates the photolytic mass loss rate by a factor of 2 to 4 at all wavelengths suggesting a potential role for reactive oxygen species. UV photolysis of an aqueous SRFA solution demonstrated both photobleaching at UV wavelengths and photoenhancement at visible wavelengths. Ultrahigh-resolution mass spectrometric analysis showed that condensed-phase SRFA photolysis led to decreased intensity in the 100-300 m/z range while aqueous SRFA photolysis resulted in an increase in intensity in the same range. This work reaffirms that photolytic mass loss is a potentially significant sink for SOA, but only on the time scale of a day or two and demonstrates that SRHA and SRFA are suitable surrogates for atmospheric SOA with respect to photolytic mass loss.
| S-EPMC11331507 | biostudies-literature