QCMD in Lipid Research

QCMD in Lipid Research Tech Note

October 15th 2020: AWSensors is pleased to invite you to take a look to its Technology Note entitled “QCMD in Lipid Research”.

Summary of the Note

QCMD is a label-free surface-analytical technique based on a quartz resonator excited to oscillate at its resonance frequency on one or more overtones. Resonators can have various coatings: gold (Au), silica (SiO2), titania (TiO2), etc. It works in aqueous media or organic solvents and is therefore widely used for studying solid/liquid interfaces. At each overtone, QCMD measures changes in the resonance frequency and energy dissipation due to the processes occurring at the resonator surface. Examples of such processes include formation of a film or changes in the geometrical or physical properties of the film.

The key feature that makes QCMD useful in lipid research is its ability to distinguish between different geometries and topologies of lipidic assemblies at interfaces, for example, homogenous solid-supported bilayers or monolayers vs. adsorbed liposomes or other structures (such as cubosomes) without relying on fluorescent or deuterated labels but by relying on the combination of the frequency and dissipation.

QCMD in Lipid Research

Introduction

Lipid-related QCMD work can be grouped into several topics, with a total of more than a thousand publications:
• Studies focusing on the interactions between lipids and surfaces.
• Studies focusing on the properties of the lipids, such as their phase behavior, adsorbed liposome deformation, etc.
• Studies examining interactions between lipids and membrane-binding proteins, peptides or viruses. Particularly interesting is that QCMD offers a way to study clustering of membrane-bound proteins.
• Studies focusing on the interactions of lipids with polymers or with nanoparticles.

 

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Making Advanced Electrogravimetry as an Affordable Analytical Tool for Battery Interface Characterization

Authors: Pierre Lemaire, Thomas Dargon, Daniel Alves Dalla Corte, Ozlem Sel, Hubert Perrot, and Jean-Marie Tarascon

Journal: Anal. Chem., 2020

Liposomes Embedded in Layer by Layer Constructs as Simplistic Exosome Transfer Model

Authors: Gerardo Prieto, Vicente Domínguez-Arca, Rui R. Costa, Ana M. Carvalho, Pablo Taboada, Rui L. Reis, Iva Pashkuleva

Journal: Research Square, 2020

High Fundamental Frequency (HFF) Monolithic Resonator Arrays for Biosensing Applications: Design, Simulations, Experimental Characterization

Authors: Román Fernández; María Calero; Ilya Reiviakine; José Vicente García; María Isabel Rocha-Gaso; Antonio Arnau; Yolanda Jiménez

Journal: IEEE Sensors Journal, 2020

Tracking Recovery

Tracking Recovery Technology Note

September 15th 2020: AWSensors is pleased to invite you to take a look to its new Technology Note entitled “Tracking Recovery Technology Note”.

Summary of the Note

Use of the AWSensors X1 Instrument Tracking Recover feature to monitor overtones frequency and dissipation shifts of air-to-liquid medium exchanges onto 5 MHz QCM sensors.

Tracking Recovery

Introduction

The Tracking Recovery feature included in AWSensors X1 platform allows the user to monitor large and fast frequency shifts in QCM (Quartz Crystal Microbalance) admittance spectrum. These sudden modifications in the sensor response are common is some applications where dramatical changes in the viscoelastic properties of the sensor surrounding medium take place.

This technical note illustrates the utility of tracking recovery feature to characterize an air-to-liquid medium exchange. According to Kanazawa and Gordon theory predictions [1], a complex frequency shift is expected in the sensor electromechanical response when the semi-infinite medium placed over the QCM’s top electrode is replaced by other semi-infinite medium. This shift will depend on the viscosity and density properties of the final medium. Following, Kanazawa-Gordon equation is presented for both the frequency (Eq. 1) and the half-bandwidth (Eq. 2) shifts.

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Biosensor

Biosensor Application Note

July 3rd 2020: AWSensors is pleased to invite you to take a look to the Biosensor Application Note entitled “Acoustic Biosensor“.

Summary of the Note

An immunosensor application for determination of carbaryl pesticide was developed by using AWS A20 research platform and AWS F20 Fluidic System. Carbaryl was chosen as the model analyte. Two kinds of acoustic sensors were employed: AWS HFF-QCM sensors (50 MHz and 100 MHz) and Love-SAW sensors with appropriate cells. The AWS A20 platform allowed monitoring phase-shift changes at constant frequency as a function of the sensor surface mass changes.

Biosensor

Introduction

Sensor functionalization: Carbaryl hapten conjugate was covalently immobilized by means of Self Assembled Monolayer (SAM).

Immunoassay format: The chosen competitive immunoassay was a binding-inhibition test based on conjugate-coated format. Carbaryl analyte competes against the immobilized hapten-conjugate for Monoclonal Antibodies.

Carbaryl detection: Samples were injected onto the sensors’ surfaces. AWS software allowed controlling sample injection and fluidics. Furthermore, the employed platform allowed performing the measurements at a constant temperature of 25°C ± 0.05°C.

Since analyte inhibits antibody binding to its respective immobilized conjugates, increasing concentrations of analyte are detected by a change in the increment of the phase-shift of the sensor. The following figures present a representative assay cycle selected from a continuous monitoring in a carbaryl determination, for 100 MHz HFF QCM and 120MHz Love Wave Sensors.

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A microsensor prototype for ocular surfacer evaluation: a preliminary step for their clinical use

Authors: Martin Zalazar; Gabriel Muñoz; Rodrigo M Torres

Journal: Investigative Ophthalmology & Visual Science, 2020

QCMD

QCMD New Technology Note

June 3rd 2020: AWSensors is pleased to announce the release of its new Technology Note on Quartz Crystal Microbalance with Dissipation entitled “AWSensors QCMD“.

Summary of the Note

Advanced Wave Sensors is a company that designs, develops, and manufactures ultra-sensitive sensing systems based on the quartz crystal microbalance with dissipation (QCMD) measurement technology. In this Note the technology basics are explained.

QCM-technology

Introduction

At the core of the QCMD technology is a piezoelectric resonator, typically made of quartz, that is excited to oscillate at its resonance frequency in the thickness-shear mode by applying an alternating current through the electrodes deposited on its surface.

With the resonator oscillating in the thickness shear mode, its two surfaces move in the opposite directions, as indicated by the arrows in Figure 2. The wavelength of the shear wave, λ, is therefore twice the thickness of the sensor, ? = 2? . Because ?? = ? , where ? = √(??/??) , is the speed of shear sound in the material and ? is the frequency, the resonance frequency of such a resonator is given by ?? = ??/2? = (?/2?) √(??/??), where ?? is the shear modulus of quartz, ?? is its density, and ? is the (odd) overtone order. The same expression may be derived formally by solving the equations describing the propagation of shear waves in elastic media subject to appropriate boundary conditions, as discussed in ref. 1. Plugging in 29×109 Pa for the shear modulus of AT quartz and 2650 kg/m3 for the density, one obtains a frequency of ~ 5 MHz for a thickness of ~ 330 um at the fundamental, where n = 1.

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Control over Electroless Plating of Silver on Silica Nanoparticles with Sodium Citrate

Authors: Jeffrey E.Chen, QifengWang, Kenneth R. Shull, Jeffrey J.Richards

Journal: Journal of Colloid and Interface Science, 2020

SLB

Lipid Bilayers New Application Note

May 15h 2020: AWSensors is pleased to announce the release of its new Application Note on Supported Lipid Bilayers (SLB) entitled “Supported Lipid Bilayer formation followed at low- and high-fundamental frequencies“.

Summary of the Note

The process of supported lipid bilayer (SLB) formation from adsorbed liposomes is a robust biophysical system that is used in laboratories all over the world. Here, it is used to test AWSensors Quartz Crystal Microbalance with Dissipation measurement (QCMD) equipment and high fundamental frequency QCMD sensors. It is shown that the AWSensors QCMD system correctly and quantitatiely reports the frequency and dissipation changes associated with the SLB formation on high- and low-fundamental frequency SiO2-coated sensors. Some differences between the two types of sensors are highlighted. SLB

Introduction

Quartz crystal microbalance with dissipation measurement, or QCMD, has become a popular technique for research in such disparate fields as material science, biophysics, electrochemistry, and immunosensing. [1] One of the reasons for the wide range of applicability and popularity of QCMD is its ability to provide information about molecular organization (topology and geometry) at solid/liquid interfaces. Specifically, it was shown how the combination of frequency and dissipation could distinguish between different surface-immobilized lipidic assemblies: adsorbed liposomes and supported lipid bilayers (SLBs; Figure 1).[2] This allowed the process of SLB formation from liposomes on SiO2-coated QCMD sensors to be followed in situ.[2] Subsequent studies further showed how the combination of frequency and dissipation measurements on various overtones could be used to study adsorbed liposome deformation [3,4] and detect mutations through the analysis of DNA conformation and length. [5, 6]

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