Lipid B1 is a next-generation ionizable lipid engineered for superior mRNA delivery, featuring a patented β-isobutylglutarate branching linker that optimizes nanoparticle assembly and intracellular release. Its unique structure combines a pH-responsive tertiary amine headgroup with twin C18 alkyl tails connected via biodegradable ester bonds, enabling precise control over lipid packing and endosomal escape. Preclinical studies demonstrate that Lipid B1-based LNPs (bLNPs) achieve **>75% transfection efficiency in vitro at ultra-low mRNA doses (1 μg), outperforming commercial benchmarks like SM-102. In vivo, subcutaneous administration of bLNPs delivers 10-fold higher luciferase expression** than linear-chain analogs, with targeted biodistribution to lymph nodes and tumor sites. Clinically relevant data show 100% tumor prevention in prophylactic cancer vaccine models and 70% tumor regression in therapeutic settings when combined with checkpoint inhibitors. The ester-based backbone ensures rapid metabolic clearance, minimizing systemic toxicity risks (NOAEL >10 mg/kg in mice). Compatible with mRNA, siRNA, and CRISPR-Cas9 payloads, Lipid B1 is ideal for vaccines, gene therapies, and immuno-oncology. Its scalable 3-step synthesis (yield >80%) and lyophilization stability (-80°C, 12 months) make it a cost-effective solution for GMP-grade production. For advanced delivery with unmatched safety and efficacy, Lipid B1 sets a new standard in nucleic acid therapeutics.