Transmission Electron Microscopy

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Transmission Electron Microscopy

Method Introduction

Electron microscopy in transmission mode (TEM) is a technique for visualizing particles using an electron source.

In contrast to Light Microscopy, where a light source is used, TEM uses an electron source to visualize molecules and particles over a large size range (~0.1 nm to several mm). It further delivers information on particles’ morphology (size, shape) and, partially, the topography (surface characteristics). TEM is mainly applied for troubleshooting or additional particle characterization. Instruments typically require experienced operators, and TEM-based methods have a low throughput. Sample preparation is crucial, and care should be taken not to introduce artifacts. Only a limited number of particles can typically be analyzed by TEM.

Applications

TEM’s high-resolution imaging capabilities make it an invaluable tool for characterizing cells, viral vectors, contaminants, and protein structures to ensure the safety, purity, and efficacy of biopharmaceutical products.

  • TEM can examine the structural integrity of cells and detect the presence of endogenous retroviral particles in cell lines like Chinese Hamster Ovary (CHO) cells used for biologic production. This helps ensure the safety and quality of the cell line.

  • For cell and gene therapies involving viral vectors, TEM allows visualization and evaluation of the viral particles’ size, shape, purity, and capsid content (full vs empty). This is crucial for ensuring proper vector assembly and potency.

  • TEM provides an unbiased way to detect and identify potential contaminants like adventitious viruses or other extraneous agents in unprocessed cell culture bulks and bioreactor harvests. This aids in monitoring microbiological safety.

Quality and Biosafety Level

We provide all our analytical services with the highest quality standards. Experienced scientists carry out each project, and a scientific reviewer comprehensively checks every report or data presentation.

We offer this technology with the following quality and biosafety levels:

R&D level

We offer this method under R&D. Our GRP system assures the highest-quality research standards.

Up to biosafety level 2

This method can be applied to nucleic acids, viruses, cells, viral vectors, including lentiviruses and more.

Transmission Electron Microscopy Frequently Asked Questions (FAQs)

  • TEM is a high-resolution imaging technique that uses an electron beam instead of light to visualize particles, molecules, and biological structures. It provides detailed information about particle size, shape, morphology, and surface features at the nanometer scale.

  • Coriolis uses TEM to analyze a wide range of biopharmaceutical samples, including viral vectors, cell lines, protein aggregates, and potential contaminants in raw materials or process streams. TEM is applicable up to biosafety level 2 (BSL-2).

  • TEM allows direct visualization of viral vector particles, enabling assessment of capsid integrity, size, shape, and content (full vs. empty). This is essential for ensuring the quality and potency of vectors in gene and cell therapy development.

  • TEM offers unbiased, high-resolution visualization of potential contaminants such as adventitious viruses, aggregates, or unidentified particles. It is especially valuable for investigating microbiological safety in cell culture bulk or harvest material.

  • Yes. TEM enables visualization of protein complexes and aggregates at near-atomic resolution, helping scientists assess structural integrity and support formulation and developability studies for biopharmaceutical drug products.

  • Unlike light microscopy, which is limited by optical resolution, TEM uses electrons to resolve structures at sub-nanometer scales. It complements other techniques like DLS, NTA, or AF4 by offering direct visual confirmation of particle morphology.

  • No. TEM typically has lower throughput due to the complexity of sample preparation, image acquisition, and analysis. It is best suited for detailed investigations, troubleshooting, or confirmatory analysis, rather than large-scale screening.

  • Coriolis offers TEM services under research-grade conditions aligned with Good Research Practice (GRP) and supports up to BSL-2 samples, including viruses, nucleic acids, and mammalian cell lines such as CHO.

  • Sample preparation is critical for TEM because artifacts can easily be introduced during grid preparation, staining, or drying. At Coriolis, experienced scientists carefully optimize preparation steps to preserve structural integrity and avoid misleading results.

  • Coriolis combines deep analytical expertise, high-quality instrumentation, and a proven track record in complex biopharmaceutical projects. Each TEM project is handled by trained specialists and undergoes thorough scientific review to ensure reliable outcomes.

Analytical Method Development, Qualification and Validation

For common sample types, we can often apply standardized methods with little setup effort. However, when needed, our experienced analytical experts create or optimize custom methods tailored to your active pharmaceutical ingredient, product type and development phase.

Method Development

Our method development approach tailors sample preparation, method settings and data analysis to the needs of your project and sample.

We include representative samples and, where available, suitable reference standards and stressed/degraded materials, allowing our analytical scientists to design a highly suitable, stability-indicating, robust and repeatable method. Upon request, we will compile a detailed description of the method for your records.

Method Qualification

Method qualification is the initial assessment of an analytical procedure’s performance to show its suitability for its intended purpose.

During method qualification, our analytical scientists perform documented testing demonstrating that the analytical procedure meets criteria in several categories. Criteria may include factors such as repeatability, specificity and robustness. We compile a qualification plan and report, including all relevant data.

Method Validation

Under GMP conditions, method validation confirms that an analytical procedure’s performance suits its intended purpose. Depending on the method’s scope, a broad range of method characteristics, such as specificity, accuracy, precision, limit of detection/limit of quantification (LOD/LOQ), linearity and range, is considered.

During method validation, our analytical scientists perform documented testing demonstrating that the analytical procedure consistently produces a result that meets the predetermined acceptance criteria. We compile a validation plan and report that includes all relevant data.

Depending on the development phase, a fit-for-purpose validation approach can be offered, adjusting the validation required efforts in a phase-appropriate way to meet the method’s needs.

Method Verification

Compendial method verification confirms that a compendial method (e.g., from Ph. Eur. or USP) is suitable and reliable for its intended purpose under the specific conditions of the laboratory.

Unlike full method validation, compendial method verification is often considered a partial validation since the method has already undergone extensive testing and validation during its inclusion in the compendium. The extent of method verification depends on the type of method.

During method verification, our analytical scientists perform documented testing demonstrating that the developed analytical method performs adequately for the specific product or matrix being tested and within the specific laboratory where the method will be employed.

Talk to Our Experts or Request a Quote

Our expert team is ready to answer your questions and guide you to the services best suited to your program’s modality, stage and challenge. If your needs are well-defined, we’ll begin the quotation process.

Description

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