Overcoming Lipid-Induced Quenching in RNA Quantification Using RiboGreen ® Assay
Résumé
Lipid nanoparticles (LNPs) have gained substantial attention in recent years, particularly following the success of mRNA vaccines from Moderna and Pfizer, for their ability to deliver genetic material like mRNA, siRNA, and miRNA. These nanocarriers are critical for gene therapies, and accurately quantifying the encapsulated genetic material is essential to assess the encapsulation efficiency (EE) and drug loading (DL) of LNPs. Traditionally, the Ribogreen assay is used for this purpose.
However, certain lipid components in LNP formulations interfere with the Ribogreen assay, reducing fluorescence intensity and leading to inaccurate EE measurements. This phenomenon, known as fluorescence quenching, skews the results and hinders the correct evaluation of RNA encapsulation in lipid-based nanovectors.
To address this issue, we tested several commonly used lipids, such as MC3, DOTAP, SM-102, and ALC-0315, at equal molar concentrations. These lipids were mixed with increasing amounts of reference rRNA provided by the Ribogreen kit. Our objective was to study the lipid concentrations enabling to observe a fluorescence quenching and to determine optimal dilutions where lipid interference no longer impacts RNA quantification. Preliminary data indicated that DOTAP at 10-4 M reduced fluorescence intensity by almost 75%, while a concentration of 10-5 M showed no quenching effect. Interestingly, MC3 at 10-4 M did not reduce fluorescence.
Future experiments will focus on testing higher concentrations of MC3 and other lipids like SM-102, used in the Onpattro® vaccine. By establishing the lipid concentrations that do not affect RNA quantification, this research aims to optimize fluorescence-based methods for accurately assessing the encapsulation efficiency of lipid nanovectors.
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