Supported lipid bilayers (SLBs) mimic biological membranes and are a versatile platform for a wide range of biophysical research fields including lipid-protein interactions, protein-protein interactions and membrane-based biosensors. the quartz crystal microbalance with dissipation monitoring (QCM-D) has had a pivotal role in understanding SLB formation on various substrates. as shown by its real-time kinetic monitoring of SLB formation, QCM-D can probe the dynamics of biomacromolecular interactions. We present a protocol for constructing zwitterionic SLBs supported on silicon oxide and titanium oxide, and discuss technical issues that need to be considered when working with charged lipid compositions. Furthermore, we explain a recently developed strategy that uses an amphipathic, a-helical (AH) peptide to form SLBs on gold and titanium oxide substrates. the protocols can be completed in less than 3 h.

Quartz crystal microbalance with dissipation monitoring of supported lipid bilayers on various substrates

Biosensors have been used extensively in the scientific community for several purposes, most notably to determine association and dissociation kinetics, protein-ligand, protein-protein, or nucleic acid hybridization interactions. A number of different types of biosensors are available in the field, each with real or perceived benefits over the others. This review discusses the basic theory and operational arrangements of four commercially available types of optical biosensors: surface plasmon resonance, resonant mirror, resonance waveguide grating, and dual polarization interferometry. The different applications these techniques offer are discussed from experiments and results reported in recently published literature. Additionally, recent advancements or modifications to the current techniques are also discussed.

https://www.mdpi.com/1424-8220/10/11/9630/pdf

Theory and applications of surface plasmon resonance, resonant mirror, resonant waveguide grating, and dual polarization interferometry biosensors.

Optical biosensor technology continues to be the method of choice for label-free, real-time interaction analysis. But when it comes to improving the quality of the biosensor literature, education should be fundamental. Of the 1413 articles published in 2008, less than 30% would pass the requirements for high-school chemistry. To teach by example, we spotlight 10 papers that illustrate how to implement the technology properly. Then we grade every paper published in 2008 on a scale from A to F and outline what features make a biosensor article fabulous, middling or abysmal. To help improve the quality of published data, we focus on a few experimental, analysis and presentation mistakes that are alarmingly common. With the literature as a guide, we want to ensure that no user is left behind.

Grading the commercial optical biosensor literature-Class of 2008: 'The Mighty Binders'.

Filamentous Bacteriophage Promote Biofilm Assembly and Function

α-Synuclein Senses Lipid Packing Defects and Induces Lateral Expansion of Lipids Leading to Membrane Remodeling

Supramolecular conformation and molecular orientation was monitored during supported lipid bilayer (SLB) formation using dual polarization interferometry (DPI). DPI was shown to enable real time sensitive determination of birefringence of the lipid bilayer together with thickness or refractive index (with the other a fixed value). This approach removes differences in mass loading due to anisotropy, so the mass becomes solely a function of the lipid dn/dc value. DPI measurements show highly reproducible qualitative and quantitative results for adsorption of liposomes of different lipid compositions and in buffers with or without CaCl2. The packing of solvent-free self-assembled SLBs is shown to differ from other preparation methods. Birefringence analysis accompanied by mass and thickness measurements shows characteristic features of vesicle adsorption and SLB formation kinetics previously not demonstrated by evanescent optical techniques, including indications of percolation-type rupture of clusters of li...

Optical Anisotropy of Supported Lipid Structures Probed by Waveguide Spectroscopy and Its Application to Study of Supported Lipid Bilayer Formation Kinetics

Protein crystallization has gained a new strategic and commercial relevance in the postgenomic era due to its pivotal role in structural genomics. Producing high quality crystals has always been a bottleneck to efficient structure determination, and this problem is becoming increasingly acute. This is especially true for challenging, therapeutically important proteins that typically do not form suitable crystals. The OptiCryst consortium has focused on relieving this bottleneck by making a concerted effort to improve the crystallization techniques usually employed, designing new crystallization tools, and applying such developments to the optimization of target protein crystals. In particular, the focus has been on the novel application of dual polarization interferometry (DPI) to detect suitable nucleation; the application of in situ dynamic light scattering (DLS) to monitor and analyze the process of crystallization; the use of UV-fluorescence to differentiate protein crystals from salt; the design of novel nucleants and seeding technologies; and the development of kits for capillary counterdiffusion and crystal growth in gels. The consortium collectively handled 60 new target proteins that had not been crystallized previously. From these, we generated 39 crystals with improved diffraction properties. Fourteen of these 39 were only obtainable using OptiCryst methods. For the remaining 25, OptiCryst methods were used in combination with standard crystallization techniques. Eighteen structures have already been solved (30% success rate), with several more in the pipeline.

/pdf/optimization-of-protein-crystallization-the-opticryst-2s0mf87hb7.pdf

Optimization of protein crystallization: the OptiCryst project

The use of dual polarization interferometry (DPI) as a tool for probing the different possible outcomes of protein crystallization experiments is described. DPI is a surface analytical technique used for the characterization of structure and interactions of molecular layers on an optical waveguide surface for a wide range of applications, including protein–protein interactions and conformational changes. The application of this technique provides a “signature” of crystallization events, thus predicting if there will be protein crystal formation, amorphous precipitate, or clear solution. The technique was demonstrated on a number of model proteins, and it also produced meaningful results in the case of two problematic target proteins. DPI in conjunction with a dialysis setup, allows changes in the protein solution above the waveguide surface to be monitored simultaneously with continuous control of its precipitant content. DPI has the potential to be used as a powerful method for discovering crystallizatio...

/pdf/use-of-dual-polarization-interferometry-as-a-diagnostic-tool-1mvtlkhdum.pdf

Use of Dual Polarization Interferometry as a Diagnostic Tool for Protein Crystallization

A method of determining a mass loading characteristic of a material of interest. An optical sensor, such as an optical waveguide sensor, is equipped with a measurement surface 4 which mimics a surface of interest such as a ceramic surface. A sample to be measured, such as a cleansing agent or detergent, is introduced from injection module 1 to liquid flow 2 through a frit 3 and into the optical sensor. Waste is recovered in chamber 7. Data recording is performed by data module 5 and outputted to a data output device 8. Once the sample has equilibrated with the measurement surface 4 sample addition is halted and the liquid flow 2 is continued. The desorption time is measured and calibrated using known techniques. The mass loading characteristic may also be a change in surface adsorption. The sensor device may be an interferometric sensor device.

Measurement of surface adsorption or desorption

The present invention relates to a method for determining crystallization in a very small amount of a material of interest (eg a chemical or biological material of interest).

Marcus Swann

Papers

Optical Anisotropy of Supported Lipid Structures Probed by Waveguide Spectroscopy and Its Application to Study of Supported Lipid Bilayer Formation Kinetics

Optimization of protein crystallization: the OptiCryst project

Use of Dual Polarization Interferometry as a Diagnostic Tool for Protein Crystallization

Measurement of surface adsorption or desorption

Method for determining a physical mass changing event