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Linear PEI 40000, a more efficient transfection reagent

Generally, transfection is the process of artificially introducing nucleic acids (DNA or RNA) into eukaryotic cells. Transfection reagents, as its name implies, are a series of reagents involved in transfection. During the process of transfection, we are often troubled by the low transfection efficiency, narrow application range, strong toxicity, cumbersome operation, and expensive price of transfection reagents. So, is there a transfection reagent that can solve these problems? Yeah, linear PEI MW 40000 is the best choice for solving these problems.

Note: Yeasen has launched GMP-grade Hieff Trans™ PEI Transfection Reagent (Cat#: 40821ES) for large-scale production of various virus vectors and transient expression of proteins suitable for adherent and suspension systems.


1. What are the types of cell transfection?

2. What is linear PEI MW 40000?

3. How does linear PEI MW 40000 work?

4. What are the features of PEI MW 40000?

5. Other transfection reagents from Yeasen

6. Regard Reading


1. What are the types of cell transfection?

Before introducing linear PEI MW 40000, let us first briefly understand the types of cell transfection. Cell transfection is of great significance for genetic research, protein research, and cytology research, which refers to the process of artificially introducing nucleic acids (DNA or RNA) into cells utilizing non-viral infection means. The main purpose of transfection is to study the function of genes or gene products, by enhancing or inhibiting specific gene expression in cells, or to produce recombinant proteins. The introduction of exogenous nucleic acid will change the characteristics of cells, so as to achieve the purpose of transfection, which is helpful for the study of gene regulation and protein expression, as well as the synthesis and production of proteins.
Cell transfections can be divided by chemical, biological and physical methods, or the residence time of a foreign gene in the cell. In transient transfection, the introduced nucleic acid can exist in the cell for a limited time without replicating, while with stable transfection, the introduced nucleic acid is integrated into the host genome and can be expressed in the progeny of the transfected cell.
With so many different cell transfection methods, how do choose the right method?
No single transfection method is suitable for all cell types and meets all experimental needs. The optimal transfection method should be selected according to the requirements of the cell type and experimental conditions.
At present, chemical transfection reagents are still the mainstream cell transfection methods due to their ease of operation and compatibility with a variety of cell lines.

2. What is linear PEI MW 40000?

Polyethylenimine Linear(PEI) MW40000 (rapid lysis) is a transient transfection reagent based on polyethyleneimine with a molecular weight of 40,000 (PEI 40000). PEI 40000 is a highly charged cationic polymer that can easily bind negatively charged nucleic acid molecules to form complexes, thereby introducing complexes into cells.
Compared with PEI 25000 transfection reagent, PEI 40000 is easy to dissolve and can be directly dissolved in water. Additionally, PEI 25000 contains 4-11% propionyl residues, which prevent the polymer backbone from binding to DNA. But PEI 40000 is a complete shed construction, so its performance is consistently efficient.

3. How does linear PEI MW 40000 work?

Polyethyleneimine (PEI) is an excellent multifunctional non-viral vector with good cell adhesion and can be used to transfect cells independently of lysosomal inhibitors. PEI and DNA are bound by electrostatic forces, causing the DNA to collapse from the loose coil-like structure into spherical particle complexes. The PEI-DNA complexes are usually positively charged to interact electrostatically with the external cellular membrane and uptaken by endocytosis. The endocytosed PEI-DNA complexes are then captured by endosomes for transfer to lysosomes for degradation. The ever-increasing internal ionic pressure causes the endosome to swell and rupture, releasing foreign DNA into the cytoplasm. This transfection mechanism is called "proton sponge" effect.
Studies have shown that PEI molecules can coat the surface of the PEI-DNA complexes to sufficiently protect DNA from being degraded by nucleases in the cytoplasm, ensuring the transit of the foreign DNA from the cytoplasm to the nucleus. Moreover, PEI molecules can insert into the phospholipide membranes and create stable channels to transfer DNA into the cell nucleus. PEI molecules do not enter the cell nucleus and play an important role as a DNA vector.
The gene expression can be detected 1-4 days after the exogenous gene is introduced into mammalian cells. This expression is due to the fact that a part of the introduced DNA is transcribed into mRNA after entering the nucleus, and then translated into the cytoplasm. Because this method is relatively simple and easy to implement, by selecting a good expression vector and transfection method, the amount of protein expression can reach a higher level. The PEI transfection reagents have been widely used in scientific research and industrial applications as a common transfection method for studying protein structure and function.

4. What are the features of PEI MW 40000?

As a transient transfection reagent with low cytotoxicity, PEI 40000 has high transfection efficiency and high gene expression efficiency in cells such as HEK293 and CHO. Linear PEI transfection reagent has been validated for a wide range of cell lines including HEK-293, HEK293T, CHO-K1, COS-1, COS-7, NIH/3T3, HepG2 and Hela cells. The transfection efficiency is as high as 80%~90%. Continue to view the performance data:

  • High transfection efficiency, suitable for adherent and suspension cells

It is suitable for a variety of cell lines including HEK-293, HEK293T, CHO-K1, COS-1, COS-7, NIH/3T3, Sf9, HepG2, and Hela cells, etc., the transfection efficiency is as high as 80%~90%.

Table 1. List of validated cell lines

Adherent cells(1 μg DNA)


Suspension cells(2 μg DNA)


















Figure 2. PEI 40000 transfected GFP plasmid into adherent cells HEK-293, the transfection efficiency reached 90% after 72 h (left); PEI 40000 transfected GFP plasmid into suspension cells CHO-K1, and the transfection efficiency reached 80% after 72 h (right)

  • Low toxicity

It ensures cell viability and improves transfection efficiency.

Figure 3. PEI 40000 provided by YEASEN has much lower cytotoxicity than competing poly**

  • The transfection efficiency is higher than that of PEI 25000, which can completely replace PEI 25000

PEI 25000 contains 4-11% propionyl residues, preventing the polymer backbone from binding to DNA. Compared to PEI 25000, PEI 40000 is a complete shed construction, so its performance is consistently efficient.

Figure 4. HEK-293 cells were transiently transfected with GFP plasmid using PEI 25000 and PEI 40000 transfection reagents, and the fluorescence was observed after 72 h. Experimental results: PEI 40000 transfection efficiency is better than PEI25000.

  • Simple configuration and short transfection time

This product is an instant type, which can be directly dissolved in water without pH adjustment. And compatible with serum and antibiotics, no need to change the medium.

  • Cost-effective, suitable for large-scale transient transfection

Compared with imported products, Yeasen PEI 40000 transfection reagent has a low price and stable batches.


Figure 5. Price comparison of PEI 40000 products of Yeasen and poly** (specification: 1 g)

5. Other Transfection Reagents from Yeasen

Yeasen has a complete product line of transfection reagents, including the current mainstream chemical transfection methods, cationic liposome reagents, and cationic polymer reagents, which can be applied to a variety of usage scenarios. In this section, we list all the transfection reagents from Yeasen and their applications in the following table, you can choose the best one which is suitable for your experiment.

Table 2. List of Yeasen Transfection Reagents


Product Name

Nucleic acid type

Cell type


Polyethylenimine Linear(PEI) MW40000 (rapid lysis)


Adherent cells 

Suspension cells


Hieff Trans™ PEI Transfection Reagent


Adherent cells

Suspension cells

40821ES Hieff Trans™ PEI Transfection Reagent GMP-grade DNA

Adherent cells

Suspension cells 


Hieff Trans™ Liposomal Transfection Reagent

DNA (<10kb), shRNA

adherent cells


Hieff Trans™ Suspension Cell-Free

Liposomal Transfection Reagent (Inquire)

DNA (<10kb)

Suspension cells(For

suspended blood cells or immune

cells, the transfection efficiency

of current chemical reagents is

not high.

Electroporation or virus method

are recommended.)


Hieff Trans™ in vitro siRNA/miRNA Transfection Reagent

siRNA、miRNA、pre-miRNA, mimic miRNA, antimiRNA

Adherent and suspension cells


6. Regard Reading

Transfection Reagent – Hieff Trans™ and PEI

In Vitro Cell Transfection Reagent Product Selection Guide

[1] Lu, Y., Yao, J., & Zhou, J. (n.d.). Formation and Aggregation Behavior of Polyethyleneimine-DNA Complexes. Department of Pharmaceutics, Nanjing 210009.
[2] Sabin, J., et al. (2022). New insights on the mechanism of polyethylenimine transfection and their implications on gene therapy and DNA vaccines. Colloids and Surfaces B: Biointerfaces, 210, 112219.
[3] Transient mammalian cell transfection with polyethylenimine (PEI). Longo PA, Kavran JM, Kim MS, Leahy DJ.