Imidazole‐Based Synthetic Lipidoids for In Vivo mRNA Delivery into Primary T Lymphocytes

Engineering T lymphocytes is an emerging approach in a variety of biomedical applications. However, delivering large biologics to primary T lymphocytes directly in vivo is technically challenging due to the low transfection efficacy. Herein, we investigated a library of synthetic lipid‐like molecules (lipidoids) for their capability of delivering mRNA into primary T lymphocytes both ex vivo and in vivo. We initially screened a library with a large structural variety of lipidoids ex vivo and identified imidazole‐containing lipidoids that are particularly potent in T lymphocytes transfection. We further optimized lipidoid structures by constructing and screening a detailed lipidoid library containing imidazole or imidazole analogues to perform a structure–activity correlation analysis. Using the lead lipidoid as a delivery vehicle for Cre mRNA in vivo through intravenous injection, we achieved 8.2 % gene recombination in mouse T lymphocytes.