The COVID-19 pandemic demonstrated the need for ways to rapidly deploy new vaccines at scale. However, a major bottleneck in current vaccine manufacturing processes is a lack of continuous monitoring of viral particles. Samples must be removed from the production line at the end of each cycle and transferred to an instrument for testing – a time-consuming step.
That’s why researchers at Purdue University, USA, and Merck & Co, developed a Raman spectroscopy-based tool to monitor viral particles in real time – and in flow conditions. Each test takes no longer than 30 seconds and leaves the viral particles undamaged.
“The study aims to reduce the time spent on quality control and enable rapid control of the process in case deviations are detected,” says Mohit S. Verma, associate professor of agricultural and biological engineering at Purdue, who led the research.
To study viral particles in flow conditions, the team designed a capillary device attached to a syringe pump. A confocal Raman microscope then captures Raman scattering from the sample after its exposure to the laser, providing a Raman spectrum specific to the sample.
The team’s initial experiments captured the Raman spectra of the sample containing both viral particles and the buffer, which contains excipients that serve as a background. The team then subtracted buffer spectra from the sample and used the processed spectra to detect and quantify viral particles. “There were multiple regions of the spectra that were specific to the viral particles and we used those for analysis,” says lead author and graduate student Shreya Athalye.
“This type of in-line analytical tool can be well integrated with continuous manufacturing processes, facilitating the monitoring of viral particles or other biologics as they are produced,” says Verma. “It will help capture defects in products and processes early on, saving a lot of time and money. It will also improve the product's yield and quality.”
The next step for the team is to explore the potential of portable Raman systems as an in-line tool for monitoring viral particles. “Portable Raman probes can be integrated into commercial manufacturing lines, providing valuable insights into the application of this technology,” says Verma. The main challenges include improving the limit of detection for the application in the early stages of the production cycle and in more complex media.
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