APOB and hepatitis B virus infection: Small interfering RNA (siRNA) constitutes a promising therapeutic modality supporting the potential functional cure of hepatitis B. A novel ionizable lipidoid nanoparticle (RBP131) and a state-of-the-art lyophilization technology were developed in this study, enabling to deliver siRNA targeting apolipoprotein B (APOB) into the hepatocytes with an ED50 of 0.05 mg/kg after intravenous injection.