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Label-free Optical Biosensor Technology Case Studies: Direct Binding and Functional Cell-based Assays.

Current label-free technologies are becoming an important part of today’s drug discovery pipelines. SRU Biosystems’ BIND® platform of label-free readers and optical biosensors uses photonic crystal technology to provide a high throughput, extremely sensitive and versatile assay system. BIND assesses an array of biomolecular interactions including receptor activation, cell adhesion, protein-protein binding, antibody characterization, fragment-based and small molecule screening and profiling. BIND technology eliminates the reliance on labels, is compatible with both biochemical and cellular applications, has the sensitivity for use with endogenous systems and primary cells, and provides the throughput and robustness required for screening and profiling environments. This article will review the biophysics of SRU’s BIND optical photonic crystal technology, summarize BIND capabilities, and present case studies of its application in real-world drug discovery environments.

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201: Identification and characterization of binding interactions of aggregating or promiscuous small molecules

Small drug-like compounds that do not fit the classical 1:1 binding inhibition behavior have been described and potentially act through formation of compound aggregates. Determining whether these aggregates cause promiscuous inhibition or more desirable target-specific inhibition is critical for prioritizing compound progression through the drug development pipeline. SRU Biosystems’ BIND® platform is a label-free detection technology used for biochemical and cell-based drug discovery applications. BIND technology produces highly quantitative data with kinetic readout and is uniquely positioned for characterizing the mechanism of action of small molecule inhibitors. This application note discusses experimental set up and data interpretation of high throughput label-free BIND assays designed to address the time-course, stoichiometry and specificity of compound binding.

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202: Measurement of Endogenous Receptor Response on Suspension Cells

GPCR activation analysis is most often performed using recombinant cells over-expressing the GPCR of interest due to the sensitivity limitations of many screening assays. This requires researchers to take the additional step of creating recombinant cell lines or clonally selecting responsive cell lines. A less timely and more physiologically relevant system based on non-recombinant cells is highly desirable. An additional challenge for high throughput processing is the common need to use adherent cells. SRU Biosystems’ BIND, label-free detection technology has the sensitivity required for detection of endogenous GPCR activation and is fully compatible with non-adherent, suspension cells eliminating the challenges faced by other detection chemistries. This application note describes the successful use a cell-based BIND assays for the label-free analysis of an endogenous G-protein coupled chemokine receptors in THP-1 suspension cells.

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203: Pharmacological Profiling of Endogenous G Protein-Coupled Receptors on the Label-Free BIND® System

GPCR subtype (Gi, Gq, Gs, G12/13 coupled) activation is measured using a number assay platforms based on various cellular responses most commonly calcium mobilization, β-arrestin localization or second messenger levels. GPCR activation is further complicated by the receptors’ use of multiple G protein signaling. SRU Biosystems’ label-free BIND technology allows for cell-based detection of all GPCR subtype activation using a single assay. Additionally, BIND technology is compatible with adherent and non-adherent cells and is sensitive enough for use with both over-expressed and endogenous GPCRs. This application note details BIND assays demonstrating agonist and antagonist compound activity on endogenously expressed Gi, Gq and Gs coupled receptors.

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204: Development of a No Wash Cell Adhesion Assay for Screening

Cell-cell and cell-matrix binding assays have been difficult to develop and deploy in screening formats. Cell adhesion assay methods require multiple steps, labeling of the cells and repeat washing of the cells to determine specifically bound cell numbers. All of these steps contribute to poor reproducibility. A label-free, no wash assay has been developed using the BIND® Reader and 384-well BIND® Biosensors to screen and characterize the specific interaction between the vascular cell adhesion molecule-1 (VCAM-1) and the α4β1 integrin, VLA-4, natively expressed on J6 Jurkat cells. Assay optimization including cation dependency and characterization of antagonists will be presented.

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HighRes Biosystems and SRU Biosystems - The 30 Second Label-Free Lab

Screening with label-free technology represents an exciting new development for drug discovery laboratories. Plate readers such as the BIND® Turbo Reader from SRU Biosystems enable label-free measurement of biochemical and cell-based assays under physiologically pertinent conditions. The BIND system uses a novel optical effect to measure even the slightest changes in binding or adherence in the proximity of the biosensor surface, delivering higher quality assay data and improved throughput at lower cost.

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