LipidBrick® Library


Cationic lipids for LNP formulation


- 20°C

Intellectual Property

EP3646854B1 & WO2024008967A1

LipidBrick® Library CAS Numbers

IM21.7c CAS# 2416939-42-7
IM3c CAS# 3044730-52-8
IM12c CAS# 3044730-55-1
IM13c CAS# 2416939-26-7
IM15c CAS# 2416939-30-3
IM16c CAS# 2416939-32-5
IM22c CAS# 3044730-57-3
IM25c CAS# 2416939-48-3


DNA and RNA therapeutics offer promising new treatments for a wide range of diseases, and lipid nanoparticles (LNPs) are an essential tool in their delivery. Those treatments include both prophylactic vaccines that prevent infection by triggering the patient’s immune system and therapeutic vaccines/drugs that will be used to cure a patient from a specific disease. As the properties of LNPs influence their delivery efficacy, their stability as well as their biodistribution, each therapy will require its own LNP formulation depending on the genetic material, application, and tissue(s)/organ(s) of interest. Thus, to tailor the delivery system to the needs, a wide variety of lipids modulating the physico-chemical properties of LNP is required to ensure therapeutic success. 

As an innovator in the field of nucleic acid delivery, Polyplus® has developed a new range of cationic lipids, named LipidBrick® dedicated to the formulation of lipid nanoparticles (LNPs). These active lipids protect the mRNA molecules and play an important role in the transfection capacity of LNPs. Importantly, by being based on an imidazolium polar head, LipidBrick® broadens the spectrum of current LNP applications in terms of potency and biodistribution by adding an overall positive charge to LNPs: this translates into greater delivery of mRNA to the lungs and/or the spleen while reducing accumulation in the liver compared to LNPs based on ionizable lipids. 

Polyplus’ goal is to support customers from R&D to commercialization. Within the LipidBrick® library, LipidBrick® IM21.7c is the cationic lipid (active lipid) used in the formulation of jetMESSENGER® and in vivojetRNA®+ , allowing a seamless transition between our ready-to-use reagents and your LNP formulation finet-uned to your specific needs and applications. 

Moreover, LipidBrick® is based on a unique lipid structure protected by an independent patent owned by Polyplus®. 

Figure: LNP-mRNA formulation using a microfluidic system.


Table: LipidBrick® Library description

LipidBrick® name Linear Formula Molecular Weight (g/mol) IUPAC name
IM21.7c C59H117ClN2 890.03 3-butyl-1-(2,6-dimethyl-14-octadecyldotriacontan-9-yl)-1H-imidazol-3-ium chloride
IM3c C41H79ClN2 635.55 (Z)-1-(heptatriacont-9-en-19-yl)-3-methyl-1H-imidazol-3-ium chloride
IM12c C48H95ClN2 735.75 1-(2,6-dimethyl-14-tetradecyloctacosan-9-yl)-3-methyl-1H-imidazol-3-ium chloride
IM13c C64H127ClN2 960.18 3-methyl-1-(24-octadecyldotetracontan-19-yl)-1H-imidazol-3-ium chloride
IM15c C53H97ClN2 797.82 3-methyl-1-(7-octadecyl-1-phenylpentacosan-2-yl)-1H-imidazol-3-ium chloride
IM16c C56H111ClN2 847.97 1-(2,6-dimethyl-14-octadecyldotriacontan-9-yl)-3-methyl-1H-imidazol-3-ium chloride
IM22c C51H101ClN2 777.83 3-butyl-1-(2,6-dimethyl-14-tetradecyloctacosan-9-yl)-1H-imidazol-3-ium chloride
IM25c C57H113ClN2O 877.99 3-(2-hydroxyethyl)-1-(24-tetradecyloctatriacontan-19-yl)-1H-imidazol-3-ium chloride

Ordering Information

Reference NumberDesignation
101000232LipidBrick® IM21.7c 50 mg
101000172LipidBrick® IM21.7c 250 mg
101000173LipidBrick® IM21.7c 1 g
101000241LipidBrick® Library Kit (8 x 50 mg)

Bulk quantities are available upon request. Please contact us  for more information.



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mRNA-LNP characterization

A proof-of-concept study was conducted to demonstrate the potential of using LipidBrick® IM21.7c in mRNA-LNP formulation. Positive controls were selected:

  • in vivo -jetRNA®+ : a ready-to-use liposome-based reagent from Polyplus®,
  • LNPs formulated with ionizable lipids (eg Dlin-MC3-DMA and/or SM-102).

Several LNP formulations were characterized using Luciferase mRNA. Polyplus cLNP formulation with LipidBrick® IM21.7c was selected based on three parameters: particle size, zeta potential and encapsulation efficiency. By modifying the distribution between lipids, Polyplus® has formulated an LNP formulation with an acceptable size (<100 nm), an overall cationic charge (~20 mV) and 100% mRNA encapsulation efficiency.

in vivo mRNA delivery efficiency and biodistribution

LNPs properties influence their mRNA delivery efficiency as well as their in vivo biodistribution. By modifying the lipid structure (i.e. liposome vs. LNP) and the overall charge of the particle, it is possible to modify the biodistribution and mRNA expression in mice by systemic injection. Indeed, Polyplus cLNPs using LipidBrick® IM21.7c lead to a different biodistribution than LNPs formulated with ionisable lipid: the latter tend to accumulate in the liver whereas LNPs with LipidBrick® IM21.7c induce higher mRNA delivery to the lungs and spleen (and less to the liver).

LNP Stability

Particle stability is very important for patient safety and drug efficacy. Degradation of LNPs or nucleic acids can lead to undesirable side effects or reduced efficacy of the drug, which can be an obstacle for health authorities in clinical trials. Polyplus® tested the stability of its cLNP formulation for 3 months, via in vitro mRNA transfection efficiency tests on Caco-2 cells (Fig. 4). This study shows a very high stability of cLNPs with LipidBrick® IM21.7c correlated with good expression when mRNA-LNPs are stored at 4°C.

LNP Safety

Next, Polyplus® sought to evaluate the effect of using LipidBrick® IM21.7c versus the validated ionizable lipid (Dlin-MC3-DMA) in the LNP formulation on the pro-inflammatory response in mice after IV injection. To perform a thorough assessment of predictive biomarkers of in vivo toxicity, commonly modulated blood cytokines known to be associated with pathological responses were analyzed. The results of this study show that the cLNP formulation with LipidBrick® IM21.7c has a similar cytokine profile to that of LNPs with ionizable lipids and elicited little or no pro-inflammatory response.

LipidBrick® Library offers new options beyond the liver

The LipidBrick® Library is composed of innovative proprietary imidazolium-based cationic lipids for LNP formulation. Modulation of their chemical structures around their imidazolium-based polar head leads to different properties of LNPs once formulated, inducing different efficacy and biodistribution profiles in vitro (see All data) and in vivo (see image and All data). Working with the LipidBrick® portfolio, it is possible to extend the use of LNPs beyond the liver and to screen and tailor the selection of the most suitable LipidBrick® based on your therapeutic applications.

All Data

Lipid Nanoparticles (LNPs) formulation


The formulation of lipid nanoparticles involves carefully selecting and combining lipid components and nucleic acids to create stable, functional, scalable, reproducible and high-quality structures.

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Innovative Solutions for mRNA Vaccine Manufacturing: A Practical Guide Using Polyplus LipidBrick® and Services
An Overview of RNA Delivery: challenges and innovation


Webinar Replay : Beyond The Liver : A novel lipid library opening new horizons for LNP developers
Webinar Replay : Fine-tuning your mRNA-LNP formulation with an innovative cationic lipid library
Webinar replay: LipidBrick® IM21.7c novel cationic lipid for LNP formulation


Poster : An innovative cationic lipid library for efficient and tunable mRNA-LNPs
Poster : Novel generation of cationic LNP offer new possibilities in the delivery of RNA therapeutics
Poster : Ready-to-use liposome-based transfection reagent is an innovative alternative to LNPs for the delivery of RNA therapeutics

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