Analytics & EM

At Paragon, EM is regularly used to support internal process development and production efforts and is offered as an independent service to clients. Our personnel are very experienced with biological preparations from protein complexes to tissue, and process hundreds of samples every year. We offer an array of standard services and also regularly work with clients to develop projects to meet their imaging needs.

Paragon’s portfolio of services include the following:

Immunogold Labeling

This method is used for the localization of specific antigens at the EM level. Samples are fixed (using lower concentrations of glutaraldehyde), processed and sectioned. The grids are immunostained, using an antigen-specific primary antibody—followed by a gold-labeled secondary antibody. Electron-dense gold particles with ultrastructural components of cells and organelles localize the desired antigens.

Provides research scientists with an added dimension to the usual fluorescence assays and is used for the detection of proteins, antigens and other areas of interest that are located on the surface, exterior or interior of cells, virus particles, tissues and other biological specimens.

Negative Staining

Samples of particles are bound to a film and contrasted with an electron dense stain. Resolutions in the nanometer range allow protein complexes, viral assembly, phage morphology and other ultrastructural information to be analyzed. With quick preparation, digital imaging and multi-sample robotic screening we aim to turn around samples quickly for morphological and purity analysis to aid in process development.

Quantitative Negative Staining

Allows for direct counting of individual particles visualized by EM along with a known concentration of latex beads. While this technique is often replaced with dynamic light scattering, analytical ultracentrifugation, QPCR or a myriad of other analytics these days (many of which we do ourselves), in some cases the development time or the nature of the particle just makes quantitative negative staining more practical.

Viral Detection

TEM is a well established method for the general detection of virus or phage in a sample. Quantitative analysis of retroviral particles in biological fluids or tissues is a standard assay offered to detect contamination in biological manufacturing. Viral detection is done by embedding the tissue, cell or concentrated fluid particulates into a resin for TEM. Paragon has scientists with extensive experience in detecting virus in tissues, cells or biological media samples.

Process Development

Learn more about our analytical capabilities that can support Process Development activities

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