- Polyethyleneimine (PEI) plays a significant and multifaceted role in the field of nanotechnology, owing to its unique physicochemical properties.
- As a highly cationic, water-soluble, and versatile polymer, PEI has been extensively employed in the design and functionalization of nanomaterials for applications ranging from drug delivery to biosensing, gene therapy, and nanocomposite fabrication. Its abundance of protonatable amine groups enables strong electrostatic interactions with various negatively charged molecules and surfaces, making it an ideal candidate for surface modification and molecular conjugation.
- One of the most important applications of PEI in nanotechnology is in gene and drug delivery systems. PEI is widely used to modify nanoparticles (e.g., gold nanoparticles, liposomes, magnetic nanoparticles, carbon nanotubes) to enhance their biocompatibility and functionality. When conjugated to these carriers, PEI facilitates the condensation and protection of nucleic acids, promotes cellular uptake, and enhances endosomal escape through the proton sponge effect. These features are particularly valuable in delivering siRNA, mRNA, and plasmid DNA into target cells for therapeutic or research purposes.
- PEI is also frequently used to functionalize inorganic nanoparticles for biosensing and diagnostic applications. Its rich amine functionality allows for easy conjugation with fluorophores, targeting ligands, and enzymes. In sensors, PEI serves as a linker or scaffold that improves the stability and reactivity of nanostructured materials, such as quantum dots or metal oxide nanoparticles. It has been used to construct electrochemical and optical biosensors for detecting biomolecules, pathogens, or environmental toxins with high sensitivity.
- In nanocomposite materials, PEI is incorporated to enhance mechanical, electrical, or antimicrobial properties. For example, PEI has been used to coat graphene, carbon nanotubes, or polymeric scaffolds, contributing to improved dispersion, adhesion, and functional integration within composite systems. These materials have potential uses in tissue engineering, flexible electronics, and filtration membranes.
- Despite its versatility, the use of PEI in nanotechnology must be carefully optimized due to its dose-dependent cytotoxicity, especially in biomedical applications. To address this, researchers have developed low molecular weight PEI, biodegradable derivatives, or PEGylated forms to reduce toxicity while maintaining functionality.
