DLS will generally measure a wider size range than NTA, but NTA offers greater resolution than DLS (even with Multi-angle Dynamic Light Scattering). Each repeat MADLS measurement takes less than 10 minutes and the sample can be kept enclosed inside the cuvette for the whole measurement to minimize the risk of contamination and operator exposure.Nanoparticle Tracking Analysis (NTA) and Dynamic Light Scattering (DLS) are complementary techniques that offer different insights into your samples. The titer values show good agreement between the two technologies, even when an aggregate peak is present. The measurements were performed on a Zetasizer Ultra, using the low-volume quartz cuvette (ZEN2112) and the particle concentration measurement, which gives both the MADLS size distribution and the concentration per peak. The data below contain the MADLS-derived viral titer values, together with the associated ELISA data, for three AAV batches. This high-quality correlation data, when combined with data collected from three separate scattering angles, allows the measurement of the AAV concentration. However, using an advanced correlation technique called Adaptive Correlation, the Zetasizer Ultra can generate rapid, high quality-data, even for samples that are typically challenging for conventional DLS instruments. n = in how many of the three repeat measurements the peak was identified.Ī typical intensity-weighted distribution profile from traditional DLS allows rapid assessment of the aggregation profile and therefore insights into the stability of the AAV preparations. All concentrations are given as particles/mL. Concentration data from capsid ELISA assay and MADLS-based particle concentration results shown for three samples: ATCC AAV2 reference sample, Allergan sample 1, Allergan sample 2. With the development of Multi-Angle Dynamic Light Scattering (MADLS®), the Zetasizer Ultra from Malvern Panalytical provides both rapid, accurate viral titer measurements and aggregation profiles in minutes.įigure. As a result, there is high demand for a method that can rapidly and directly measure AAV particle concentration. However, these methods require hours or even days to complete. Due to its small size, AAVs are too small for titer determination from some existing rapid measurement technologies, such as Nanoparticle Tracking Analysis, and so industry has adopted techniques like quantitative polymerase chain reaction (qPCR) and colorimetric assays such as enzyme-linked immunosorbent assay (ELISA) to measure genome counts and capsid proteins, to estimate AAV titer. To date, there have been over 130 clinical trials worldwide utilizing AAV as a viral vector.ĭespite the well-known structure of AAV, gene therapy researchers are still limited in their ability to rapidly measure AAV particle concentration. Adeno-Associated Virus (AAV) is a small virus with a diameter of approximately 25 nm and has become the viral vector of choice for most gene editing therapies due its attractive properties, including its low pathogenicity, ability to infect non-dividing cells, ability to integrate into a specific location on human chromosome 19 and its tunable tropism toward different tissue types.
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