Spleen-targeted ionizable lipid compound, composition comprising same and use thereof

A lipid compound of formula (I),

• wherein
• R2a and R3a are each independently selected from the group consisting of hydrogen, a monovalent aliphatic group, a monovalent heteroaliphatic group, a monovalent aromatic group, a monovalent heteroaromatic group, and Ht;
• t and s are each independently 0 or 1, and when t or s is zero, it means that the part is directly a single bond, provided that t and s are not both 0;
• A1, A2, and A3 are each independently selected from the group consisting of a single bond, a divalent aliphatic group, a divalent heteroaliphatic group, a divalent aromatic group, and a divalent heteroaromatic group;
• each Ht is independently at each occurrence —R1—X—R2—Y—R3—Z—R4,
• wherein
• each R1 is independently at each occurrence selected from the group consisting of a divalent aliphatic group, a divalent heteroaliphatic group, a divalent aromatic group, and a divalent heteroaromatic group;
• each X is independently at each occurrence
• wherein
• m is 1-6;
• W is selected from the group consisting of O, S, and NRc;
• L1 is directly connected to R1 or R2 and is independently selected from the group consisting of a single bond, O, S, and NRd;
• L2 independently is selected from the group consisting of a bond, O, S, and NRe;
• wherein Rc, Rd, and Re, are each independently selected from the group consisting of hydrogen, hydroxy, an oxyaliphatic group, a monovalent aliphatic group, a monovalent heteroaliphatic group, a monovalent aromatic group, and a monovalent heteroaromatic group;
• Y and Z are each independently at each occurrence selected from the group consisting of S and O;
• each R2 is independently at each occurrence selected from the group consisting of a single bond, a divalent aliphatic group, a divalent heteroaliphatic group, a divalent aromatic group, and a divalent heteroaromatic group;
• R3 is independently at each occurrence
• each R4 is independently at each occurrence a hydrophobic group selected from the group consisting of —(CH2CH2O)y—C1-2 alkyl, —(CH2CH2O)y—C2 alkenyl and —(CH2CH2O)y—C2 alkynyl, wherein y is 0 or 1 or 2.