Researchers at the University of Pennsylvania reported a redesign of ionizable lipids that produces “aroLNPs,” lipid nanoparticles that substantially reduce liver delivery and preferentially accumulate in lymph nodes in mouse models. The team published data in JACS showing aromatic, bioreducible ionizable lipids with tuned tail lengths conferred lymph‑node tropism and robust antigen‑specific immunity. The paper suggests a delivery strategy to focus mRNA vaccines and immunotherapies on immune tissues, potentially improving efficacy and lowering off‑target liver exposure; authors highlighted structure–function rules for lipid regiochemistry and biodegradability.