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How to estimate AAV capsid titer with mass photometry

AAV capsid titer is a key analytical attribute of AAV samples


The total concentration of AAV capsid in a sample, or capsid titer, is a critical factor in AAV sample quality, influencing aggregation and representing important information for downstream recovery and purification processes. On the other hand, titer of full AAVs – the concentration of AAV capsids that contain the genetic material to be delivered – is a crucial factor determining the potency of a product and vital information for clinical dosing.

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Why use mass photometry for AAV titer estimation?

Mass  photometers are ideal tools for analysis of AAV samples and AAV titer estimation as they:


  • Require very little sample volume and minimal sample preparation

  • Are benchtop instruments that require minimal operator training

  • Measurements are quick, results in <5 minutes


These strengths make mass photometry an efficient and easy technique to implement in environments that require repeated AAV capsid titer measurement, such as process development

To learn how to efficiently estimate titer of empty, full and partial AAV populations with mass photometry

AAV titer estimation with mass photometry

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Read this tech note to learn how mass photometry can estimate titers of empty, full and partially filled AAV populations from AAV samples. The note also shows how the AAV titer estimation function in the data acquisition software can be easily activated during routine mass photometry measurements of AAV samples.


Here you can find data that showcases the reproducibility of mass photometry for AAV titer estimation, as well as comparisons with other techniques like ELISA and dPCR.

Additional resources​


Streamlining AAV characterization with automated mass photometry


In this webinar, Svea Cheeseman, Director of Product Management for Cell and Gene Therapy at Refeyn, discusses how mass photometry can be used to characterize AAV capsids – by measuring the empty/full capsid ratio for AAVs of any serotype with low sample consumption. She also introduces the SamuxMP Auto, Refeyn’s automated mass photometer.

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Comparing analytical approaches for AAV characterization


Read this blog post to learn how mass photometry compares to other AAV analytical methods for empty/full AAV capsid measurements.

To learn more about how mass photometry can streamline your AAV sample characterization workflows

More Application Notes

Browse through our catalogue of application notes highlighting some recent case studies featuring mass photometry.

Investigating lentivirus titer with macro mass photometry


Mass photometry supports membrane protein purification protocols 

Characterizing protein oligomerization with automated mass photometry

Quantifying heterogeneous AAV capsid loading using mass photometry

Download the application note

Download the app note
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