​​Lipid 10a-26​​ is an ionizable lipid developed by Orna Therapeutics for lipid nanoparticle (LNP) formulations. It features a biodegradable ester backbone and an ionizable headgroup, enabling efficient encapsulation and delivery of circular RNA (oRNA). Experimental data show that Lipid 10a-26 mediates robust protein expression in hepatocytes and immune cells (e.g., T cells), with strong liver-targeting specificity observed in vivo. Its optimized hydrolysis profile ensures stable oRNA delivery and reduced immunogenicity. For instance, LNPs formulated with Lipid 10a-26 (molar ratio 50:10:38.5:1.5) demonstrate high transfection efficiency in splenic B cells and sustained therapeutic protein production.The lipid’s design balances efficacy and safety, making it ideal for applications like CAR-T therapy and hepatic protein replacement.

A5-CE-C7-6 is an ionizable lipid engineered for spleen-targeted mRNA delivery, integrating a hydroxylated dual-amine core (A5) for enhanced mRNA binding and endosomal escape, a biodegradable carbonate ester linker (CE) enabling rapid hydrolysis (61% degradation in 24 h), and branched heptyl hydrophobic tails (C7-6) that optimize nanoparticle stability and spleen tropism.​​ When formulated into cholesterol-free lipid nanoparticles (B-8 formulation), its unique architecture—combining hydroxyl groups for cellular uptake, carbonate-mediated biodegradability, and branched-chain fluidity—achieves unprecedented efficiency: low pKa (~6.0) minimizes liver accumulation while enabling ​​21% transfection of splenic NK cells​​, outperforming benchmark systems like MC3 SORT LNPs by >10-fold in spleen-specific delivery and establishing a new standard for in vivo immune cell engineering.

DMA4-H228 is a novel, biodegradable lipidoid specifically engineered for spleen-targeted mRNA delivery.​​ Its structure combines a dimethylamino (DMA4) headgroup with a unique hyperbranched lipid tail (H228) synthesized via Michael addition, incorporating ester bonds for enhanced biodegradability. This design enables the formation of stable lipid nanoparticles (LNPs) (~170 nm) with high mRNA encapsulation efficiency (>96%). Critically, DMA4-H228 exhibits exceptional intrinsic tropism for the spleen (>98% targeting efficiency after IV administration), requiring no external targeting ligands. It selectively delivers mRNA to splenic antigen-presenting cells (APCs), including dendritic cells, macrophages, and B cells. This triggers potent immune activation: rapid IFNα secretion, upregulation of APC maturation markers (CD86/CD40), and robust antigen-specific immune responses. Demonstrating significant therapeutic potential, DMA4-H228-based mRNA vaccines effectively inhibit tumor growth in melanoma models (e.g., B16F10-OVA). This correlates with increased tumor-infiltrating CD8⁺ T cells, a shift towards pro-inflammatory M1 macrophages, elevated antigen-specific antibodies (IgG), and strong T cell responses (evidenced by IFNγ⁺ spots). Its ability to bypass liver tropism and directly activate splenic APCs makes DMA4-H228 a powerful platform for next-generation mRNA vaccines and cancer immunotherapy.

CICL 207 is structurally optimized based on Lipid CICL-1. CICL207​​ is a constrained ionizable cationic lipid designed for lipid nanoparticle (LNP) delivery systems developed by Capstan. Its structure features a ​​rigid cyclic backbone​​ (e.g., pyrrolidine-derived core) paired with a ​​tertiary amine group​​ that ionizes at acidic pH (pKa ~6.5–7.0), enhancing endosomal escape. The lipid includes ​​asymmetric hydrophobic tails​​ (likely C14–C18 alkyl/ester chains) to stabilize LNP membranes and improve nucleic acid encapsulation. Integrated into LNPs (e.g., 58% CICL-207, 10% DSPC, 30.5% cholesterol, PEG-lipids), it enables targeted delivery to T cells (anti-CD5/CD8 tLNPs) with ​​high transfection efficiency​​ (spleen T cells >70% mCherry+), ​​reduced liver uptake​​, and ​​low toxicity​​ (no significant ALT/AST elevation in rats). Its constrained design balances stability, tissue specificity, and biocompatibility for gene therapy applications.CICL 207 (F50) significantly outperforms CICL-1 by delivering dramatically enhanced target cell transfection with reduced off-target effects. It achieves >50% transfection efficiency in splenic T-cells—nearly double that of CICL-1—while slashing off-target expression in liver cells to <5% (versus >15% for CICL-1. This precision translates to superior therapeutic outcomes: CICL-207 enables ~95% B-cell depletion in CAR-T applications, far exceeding CICL-1 ’s ~60% efficacy. Critically, it maintains an exceptional safety profile, showing no significant liver toxicity or inflammatory cytokine elevation even at high doses. Furthermore, CICL-207 demonstrates 2-fold higher transfection efficiency in hematopoietic stem cells, enabling robust gene editing. Its optimized pKa (~6.5) and constrained amine structure enhance endosomal escape while minimizing Kupffer cell uptake, making it ideal for targeted therapeutics requiring both potency and safety.​

E10i-494 is a branched ionizable lipid designed to enhance the delivery of mRNA and CRISPR-Cas9 ribonucleoprotein (RNP) complexes. It belongs to the Branched Endosomal Disruptor (BEND) lipid family, which features terminal branching to improve endosomal escape and cellular uptake.E10i-494 demonstrated exceptional performance in T cell engineering, achieving >80% transfection efficiency in primary human T cells. This is significantly higher than the ~70% efficiency achieved by the linear lipid C14-494.The isopropyl branch enhances the lipid's ability to penetrate and disrupt endosomal membranes, leading to improved release of mRNA and RNPs into the cytoplasm.Despite its high efficiency, E10i-494 exhibits low cytotoxicity, making it suitable for therapeutic applications.E10i-494 is particularly effective for delivering mRNA to T cells, making it a promising tool for CAR-T cell therapy and other immunotherapies.Its ability to deliver CRISPR-Cas9 RNPs efficiently also makes it suitable for in vivo gene editing applications.

ADA (Acid-Degradable Anionic Lipids) is revolutionizing mRNA delivery with its unique azido-acetal linker, enabling rapid hydrolysis in endosomes (pH ~6.0). This breakthrough technology ensures efficient endosomal escape, significantly enhancing mRNA delivery to target cells. ADA-LNPs excel in delivering mRNA to the spleen and liver, making them ideal for immune-related therapies.By degrading into biocompatible byproducts, ADA minimizes long-term tissue persistence and toxicity.ADA-LNPs outperform traditional LNPs, delivering mRNA more effectively to immune cells like macrophages and B cells.

​TOT-5​​, a tri-oleoyl-Tris ionizable lipid (pKa 6.2), enables splenic B cell-targeted mRNA delivery via 15% DSPC-incorporated LNPs. Its charge-neutral, hydrophobic surface minimizes hepatic ApoE uptake and enhances complement C3 adsorption, facilitating CD21/35-mediated uptake by marginal zone B cells. In vivo, intravenous 15%DSPC-LNPs showed 8-fold higher spleen-to-liver luciferase expression vs 3%DSPC, with anti-CD21/35 blocking 60% B cell uptake. Intramuscular administration induced robust OVA-specific IgG (10^5 titer) and CTL responses (3.5% tetramer+ CD8+ T cells) while reducing hepatotoxicity (ALT/AST levels ≤40 U/L vs SM-102-LNPs' 80-120 U/L). Cryo-ET confirmed stable lamellar structures (80-100 nm, ζ-potential -2 mV). This formulation achieves safe, ligand-free splenic targeting for mRNA vaccines. 

Lipid 119-23 is an ionizable lipid for mRNA delivery. 119-23 LNP exhibits an enhanced capability to express functional mCre in several categories of immune cells, spanning the liver, spleen and lung.

PPZ-A10 is an ionizable cationic lipid.It has been used in the generation of lipid nanoparticles (LNPs) for the delivery of siRNA and mRNA in vitro and in vivo. Intraperitoneal administration of LNPs containing PPZ-A10 and encapsulating an mRNA reporter preferentially accumulates in hepatic Kupffer cells and splenic macrophages in mice.

93-O17O is a chalcogen-containing ionizable cationic lipidoid. It has been used in the generation of lipid nanoparticles (LNPs). LNPs containing 93-O17O localize to the spleen after intravenous injection into mice.LNPs containing 93-O17O have been used for the delivery of Cre recombinase and ribonucleoproteins for genome editing in mice and for the intratumoral delivery of cGAMP to enhance cross-presentation of tumor antigens.

Lipid88​​ is a high-performance, novel ionizable lipid component engineered for advanced mRNA-LNP vaccine delivery. LNP88 formulation demonstrates superior biodistribution, achieving >10-fold higher transfection efficiency in spleen and lymph nodes compared to benchmark lipids like ALC-0315 via intramuscular delivery. When encapsulating antigen-encoding mRNA (e.g., optimized mCSA construct), Lipid-88 based LNPs drive robust humoral and cellular immunity, enabling complete protection against challenging SARS-CoV-2 variants (WA1/2020, Omicron BA.1, BQ.1) in preclinical models. Its design prioritizes potent immunogenicity with favorable safety profiles.

C14-4 (C14-494,Lipid B-4,Lipid B4) is a novel ionizable lipid with the highest T-cell transfection efficiency and low cytotoxicity.The C14-4 ionizable lipid has been explored for CAR-T therapy.To screen the excellent formulations for mRNA delivery, a lipid library of 24 ionizable lipids was constructed to make iLNPs, which were used to deliver luciferase mRNA into Jurkat cells.[115] The optimal iLNPs formulation was C14-4 iLNPs (C14-4 ionizable lipid, DOPE, chol, and PEG at a molar ratio of 35%, 16%, 46.5%, and 2.5%) (Figure 6c). The optimal dose of luciferase mRNA for C14-4 iLNPs was 30 ng. Compared with electroporated CAR T cells, the CAR T cells engineered via C14-4 iLNPs showed potent cancer-killing activity when they were cocultured with Nalm-6 acute lymphoblastic leukemia cells. To obtain a safer and more effective CAR mRNA delivery vehicle, the orthogonal design provided 256 potential formulations, and 16 representative iLNPs formulations were evaluated.Through evaluating the safety, delivery efficiency, and transfection efficiency of 16 iLNPs, the formulation B10 (C14-4 ionizable lipid, DOPE, chol, PEG at a molar ratio of 40%, 30%, 25%, and 2.5%) was screened out as the optimal performing formulation. The luciferase expression based on B10 formulation was increased threefold than the initial formulation. Reducing the accumulation and clearance of iLNPs in the liver can increase the expression of CAR mRNA in T cells, further improving the therapeutic effect of CAR-T. Studies have shown that cholesterol analogs can alter the mechanisms of intracellular circulation and enhance the delivery of mRNA, which may be related to the reduced recognition of iLNPs by the Niemann Pick C1 (NPC1) enzyme.The addition of a hydroxyl group to various locations in the cholesterol molecule can alter the binding kinetics between the modified cholesterol and NPC1, and reduced NPC1 recognition of cholesterol. The results showed that replacement of 25% and 50% 7 α-hydroxycholesterol for cholesterol in iLNPs improved mRNA delivery to primary human T cells in vitro by 1.8-fold and twofold, respectively.C14-4 is one of the ionizable lipids to efficiently deliver mRNA to Jurkat cells or primary human T cells. It will effectively promote the development of mRNA delivery by iLNPs for CAR-T therapy.

503O8,12​​ is an ionizable lipidoid synthesized via Michael addition, combining a hydrophilic amine headgroup ("503" series) with two hydrophobic branched acrylate tails (C8 and C12 chains, likely with unsaturated bonds). Its design emphasizes organ-specific delivery, exhibiting ​​spleen-tropic targeting​​ in vivo.

YSK 12C4 is an ionizable cationic lipid primarily used to enhance siRNA cellular delivery via multifunctional envelope-type nanodevices (MEND). YSK 12C4 promotes siRNA uptake and endosomal escape, effectively silencing genes in human immune cell lines.

Lipid C12-A1 is an ionizable lipid. C12-A1-LPN is a potent and safe LNP platform to deliver Foxp3 mRNA to CD4+ T cells to engineer immunosuppressive FP3T cells. C12-A1 has a slightly lower average cell viability than C14-A1.

Lipid C14-A1 is an ionizable lipid. C14-A1-LPN is a potent and safe LNP platform to deliver Foxp3 mRNA to CD4+ T cells to engineer immunosuppressive FP3T cells.

IAJD 294 is a ​​single-component ionizable amphiphilic Janus dendrimer​​ that autonomously coassembles with mRNA via simple injection into uniform monodisperse dendrimersome nanoparticles (DNPs, 85 nm diameter, PDI<0.2), eliminating complex multi-component formulations. Its optimized ​​3,5-benzoyl ester linkage​​ and symmetric hydrophobic tails enable ​​dual-organ targeting​​: ​Spleen​​: 2.97 × 10⁷ RLU (50% of total activity) ​​Lymph nodes​​: 10⁶ RLU (10× higher than IAJD 87) through ​​partial hydrophobic interdigitation​​ (stabilizing DNPs for enhanced lymphatic uptake) and ​​pKa ~6.5​​ (facilitating endosomal escape), validating constitutional isomerism for precision delivery.

Westgene lipid 8 is a cationic lipid featuring a tertiary amine core with three alkyl chains (C1-C15) and two unsaturated C18 linoleate-like tails. Its ionizable amine enables pH-dependent charge for mRNA encapsulation in LNPs. Key structural elements include branched alkyl groups (X1/X2: C4, X3: C2) and ester-linked unsaturated R1/R2 chains, enhancing membrane fusion and endosomal escape. N Used in lipid nanoparticles (LNPs) with DOPE, cholesterol, and PEG-DMG, it demonstrates low cytotoxicity, high mRNA delivery efficiency, and spleen-targeted immune activation, making it suitable for vaccine/therapeutic delivery.

Sail Lipid 2308​ is a novel ionizable lipid targeting to spleen developed by Sai Biomedicine.As described on US20250205167A1, Lipid 2308 was designed with a ​​piperidine core​​ (6-membered ring) and asymmetric C17/C11 chains, this lipid achieves unprecedented ​​spleen-specificity​​. It demonstrates dominant spleen accumulation (Spleen RLU: ​​7.8E+06​​, 91.8% of total signal) with a record ​​spleen-to-liver ratio of 112.7​​ (9× higher than 2231). Despite lower protein expression (hEPO: 11,000 ng/mL), near-zero liver uptake (Liver RLU: 66,000) makes Lipid 2308 unparalleled for vaccine/immunotherapy applications targeting splenic immune cells.

Lipid I97 is a vitamin B5-derived ionizable lipid for mRNA vaccine delivery. Lipid I97 LNP specifically delivers the mRNA to the spleen and lymph nodes in model mice, induces balanced Th1/Th2 immune responses, and elicits the production of high levels of neutralizing antibodies with low toxicity.

Sail Lipid 2231 is a novel ionizable lipid targeting to spleen developed by Sai Biomedicine.As described on US20250205167A1 Lipid 2231 features  a ​​pyrrolidine core​​ (5-membered ring) with biodegradable ester linkages and asymmetric C17/C11 hydrophobic chains. In vivo data shows moderate spleen targeting (Spleen RLU: ​​3.8E+06​​) with a spleen-to-liver ratio of ​​12.767​​. 

YK-TLR-001 is a cyclic acetal-based ionizable lipid for mRNA delivery. YK-TLR-001 LNPs are demonstrated to enhance mRNA expression in the spleens and to induce exceptional maturation of antigen-presenting cells (APCs) and to promote antigen presentation.

E8i-200 is a novel Branched Endosomal Disruptor (BEND) ionizable lipid, designed to enhance the efficiency of lipid nanoparticles (LNPs) in drug delivery, particularly for mRNA and protein delivery. Its unique structure, featuring terminal branching, improves endosomal escape, a critical step in the delivery of therapeutic cargo into cells.E8i-200 is designed to enhance endosomal escape, a key bottleneck in mRNA and protein delivery. Its terminal branching structure provides several advantages:Improved Endosomal Membrane Penetration: The branched structure allows E8i-200 to more effectively disrupt endosomal membranes, facilitating the release of mRNA and proteins into the cytoplasm.Enhanced Gene Editing Efficiency: E8i-200 has been shown to significantly improve the delivery of CRISPR-Cas9 ribonucleoprotein (RNP) complexes, enabling efficient gene editing in vivo.E8i-200 significantly enhanced mRNA expression in the liver, outperforming traditional linear lipids like C12-200 in mouse models.E8i-200 effectively delivered CRISPR-Cas9 RNP complexes, achieving high editing efficiency in the liver, surpassing that of linear lipids.E8i-200 also showed high transfection efficiency and low cytotoxicity in T cells, making it a promising candidate for CAR-T cell engineering and other immunotherapies.

Si12-C10 is a siloxane-incorporated lipid for spleen-targeting mRNA delivery. The siloxane moieties enhance cellular internalization of mRNA-LNPs and improve their endosomal escape capacity, augmenting their mRNA delivery efficacy.

ORNA lipid 144​​ is a novel ionizable lipid engineered for splenic RNA delivery developed by ORNA Therapeutics, featuring a biodegradable structure with a protonatable tertiary amine headgroup and ester-linked branched C14 alkyl chains. This design enables exceptional spleen-targeting capability, demonstrated by 3-fold higher luciferase expression in the spleen compared to benchmark lipids and near-complete B-cell depletion when delivering anti-CD19 CAR circRNA. It forms highly stable lipid nanoparticles maintaining homogeneous size (60–80 nm) and low polydispersity across diverse manufacturing conditions and buffer systems. Rapid clearance from the liver and spleen minimizes off-target accumulation, while high circRNA encapsulation efficiency (>90%) and pH-dependent endosomal escape make it ideal for immunotherapies and vaccines requiring precise splenic bioavailability and sustained efficacy.

AX6​​ is an ionizable lipid in the ​​F32 LNP​​ formulation, engineered by ReNAgade/Orna Therapeutics for targeted mRNA delivery to T cells. AX-6's unique ​​bridged bicyclic/polycyclic core​​ with a ​​tertiary amine group​​ enables pH-dependent protonation and endosomal escape, while ​​C14-C18 hydrophobic tails​​ (optionally branched/fluorinated) enhance bilayer stability and mRNA encapsulation. Demonstrating ​​exceptional T-cell tropism​​, AX6 achieves high transfection efficiency in CD4+/CD8+ T cells (validated in NHP/humanized models) with minimal toxicity. Compared to clinical benchmarks (SM-102, ALC-0315), its rigid core offers superior ​​serum stability​​ and ​​immune-cell specificity​​, positioning it as an ideal candidate for ​​CAR-T/NK therapies​​ and ​​next-gen vaccines​​. The F32 LNP system's proven efficacy (e.g., in vivo B-cell depletion) underscores AX 6's transformative potential for ​​cell engineering​​ and ​​immunotherapies​​.

U-101 is an ionizable lipid for mRNA delivery. U101-LNP/IL-2F mRNA formulation demonstrats effective antitumor activity and safety.LNPs containing lipid U 101 and encapsulating mRNA encoding a fusion protein composed of IL-2, a linker, and CD25 inhibit tumor growth in an MC-38 mouse xenograft model.