Laser Technique Checks mRNA Vaccine Integrity Without Destroying the Sample

mRNA vaccines and therapeutics depend on a critical packaging step: the messenger RNA must be enclosed inside lipid nanoparticles, tiny fatty spheres that protect the fragile molecule from degradation and shuttle it into cells. If mRNA leaks out of those particles before reaching its target, the therapy fails. Quality control - confirming that mRNA is properly encapsulated - is therefore essential to ensuring that what gets injected actually works.

Current methods for checking encapsulation typically require breaking apart the lipid nanoparticles to analyze their contents. This is both destructive, meaning the tested sample cannot be used or preserved, and time-consuming. For a field where rapid quality assessment matters - particularly for cold-chain products that degrade quickly and for emerging therapeutic applications where sample volumes are limited - these are real constraints.

Chemist Igor Lednev at the University at Albany has spent two decades developing Raman spectroscopy applications for forensic and medical contexts. His lab has now turned the technique toward mRNA vaccine quality control, with results published in Analytical Chemistry.

What Raman Spectroscopy Measures

Raman spectroscopy works by directing a laser at a sample and capturing the light that scatters back. Most scattered photons return at the same frequency as the incoming laser - the elastic scattering. But a small fraction interacts with the molecular bonds in the sample and returns at shifted frequencies. That pattern of frequency shifts is unique to the molecular composition of the material, functioning as a chemical fingerprint.

The technique is non-destructive: the sample is not altered by the laser, and can be preserved for subsequent testing. The measurement itself is effectively instantaneous, limited only by detector sensitivity and signal processing time.

The Challenge of Detecting mRNA Inside Nanoparticles

Standard Raman spectroscopy faces a specific problem in this application. The lipid nanoparticles vastly outnumber the mRNA molecules in any given sample - mRNA is present in relatively tiny amounts compared to the surrounding fatty shell material. The lipid signal dominates the spectrum, making the mRNA signal difficult to resolve.

The Lednev lab's solution is a specialized deep ultraviolet (deep-UV) Raman instrument developed in-house. By shifting the laser into the deep ultraviolet range, the technique selectively amplifies the signal from nucleic acids like mRNA while minimizing interference from the lipid environment. Combined with advanced statistical analysis, the method produces a quantitative readout of mRNA encapsulation status.

"Intact lipid nanoparticles are not very stable and are difficult to characterize by existing techniques," said Alexander Shekhtman, a professor in UAlbany's Department of Chemistry and collaborator on the project. "Raman spectroscopy allows us to analyze mRNA inside lipid nanoparticles without damaging it. This means we can optimize formulations to improve both safety and effectiveness."

Potential Applications in Vaccine Manufacturing

Lednev envisions the technique being used in two settings. During research and development, it could provide rapid feedback on how formulation changes affect encapsulation efficiency - currently a time-consuming trial-and-error process. In manufacturing, it could serve as a real-time quality control checkpoint before batches are released.

"We are using our homebuilt instrument to directly analyze mRNA molecules in vaccine samples," Lednev said. "Combining this with an advanced statistical analysis, we have created a quantitative method for ensuring the mRNA is properly protected in lipid nanoparticles."

mRNA therapeutics have expanded well beyond COVID-19 vaccines to include cancer treatments, rare disease applications, and investigational approaches to conditions ranging from HIV to heart failure. Each of these requires robust encapsulation verification, making quality control methods that are fast and non-destructive increasingly valuable.

Current Limitations

The deep-UV Raman instrument used in this work is a custom-built system developed within the Lednev lab - not a commercial device available to manufacturers. Translating the technique to industrial quality control settings would require either commercializing a similar instrument or adapting the method to work with commercially available Raman equipment, which may not achieve the same sensitivity to mRNA signals within intact nanoparticles.

The current publication demonstrates proof of concept. Validation across different mRNA sequences, lipid formulations, and storage conditions - as well as comparison with existing gold-standard encapsulation measurements - would be needed before the technique could be adopted in regulated manufacturing environments.

The research is supported by a collaboration with Kangwon National University in South Korea, with Sila Jin receiving a two-year training grant from the National Research Foundation of Korea to conduct research at UAlbany.