TF19 – Polyethylenimine (PEI)

Polyethylenimine (PEI) is a classic cationic polymer widely used in DNA/RNA transfection, gene delivery, recombinant protein expression, and biomaterials research due to its strong nucleic acid-binding and delivery capabilities. The physicochemical properties and delivery performance of PEI are closely associated with its molecular weight, polymer structure (linear or branched), charge characteristics, and specific application requirements. Different grades of PEI may differ in nucleic acid-binding capacity, transfection efficiency, and cell compatibility. Therefore, the appropriate PEI material should be selected according to the cell type, nucleic acid type, and experimental objectives.

Browse the PEI products below to learn more about the characteristics and applications of different PEI grades and types. If you need help selecting the right PEI material, visit our PEI Center for more product information, selection guides, and technical resources.

Linear PEI

Linear Polyethylenimine (Linear PEI) has a relatively regular linear molecular structure and is composed primarily of secondary amine groups. The abundant protonatable amine groups along its polymer chains can interact electrostatically with negatively charged nucleic acids to form PEI/nucleic acid complexes, thereby promoting cellular uptake and intracellular delivery of nucleic acids.

The performance of Linear PEI is closely related to its molecular weight. Products with different molecular weights can meet various needs, ranging from basic polymer research to nucleic acid delivery and cell transfection. Higher-molecular-weight Linear PEI generally exhibits stronger nucleic acid binding and delivery capabilities and is therefore commonly used for DNA transfection, transient protein expression, and bioprocessing-related research.

Main Applications:

DNA Transfection · Nucleic Acid Delivery · Transient Protein Expression · Bioprocessing

Branched PEI

Branched Polyethylenimine (Branched PEI) has a highly branched three-dimensional molecular structure and contains different types of amine groups, including primary, secondary, and tertiary amines. The abundance of amine groups gives Branched PEI a high cationic charge density, enabling extensive electrostatic interactions with nucleic acids, anionic polymers, particles, and material surfaces.

Compared with Linear PEI, Branched PEI has a different molecular configuration and distribution of amine groups, resulting in distinct properties in nucleic acid binding, complexation, surface adsorption, and material interactions. Branched PEI products with different molecular weights can be used in research involving nucleic acid delivery, surface modification, dispersion and complexation, coatings, and biomaterials.

Main Applications:

Nucleic Acid Delivery · Surface Modification · Complexation · Dispersion · Biomaterials Research

Transfection Grade PEI

Transfection Grade PEI is a PEI product specifically quality-controlled and performance-validated for cell transfection applications. Compared with conventional PEI primarily used for polymer or materials research, Transfection Grade PEI places greater emphasis on material purity, batch-to-batch consistency, nucleic acid delivery, and cell transfection performance, making it suitable for establishing stable and reproducible in vitro transfection systems.

Transfection Grade PEI primarily promotes nucleic acid entry into cells by forming positively charged polymer/nucleic acid complexes with nucleic acids such as DNA. Its buffering capacity also contributes to the intracellular release of the complexes. PEI products with different molecular weights, structures, and formulations may differ in transfection efficiency and cell compatibility. Therefore, the appropriate product should be selected according to the cell type, nucleic acid type, and experimental objectives.

Main Applications:

DNA Transfection · Transient Protein Expression · HEK293/CHO Transfection · Suspension Cell Transfection · Viral Vector Production · Bioprocess Development