Primary amine group (NH2)

Primary amine groups (-NH2) are fundamental chemical functional groups found at the N-terminus of polypeptide chains and on the side chains of lysine residues in proteins and various ligands. In the field of nanomedicine and drug delivery, these groups serve as essential reactive handles for the covalent attachment of targeting moieties or therapeutic proteins to synthetic polymers (Grabarek, Z., & Gergely, J., Analytical Biochemistry, 1990). The reaction with PLA-PEG-NHS involves a nucleophilic attack by the amine on the NHS ester, creating a stable amide linkage that functionalizes the surface of nanoparticles or micelles (Jokerst, J. V., et al., Nanomedicine, 2011). This bioconjugation strategy is widely employed to enhance the pharmacokinetics, stability, and tissue-specific targeting of drug delivery systems (Peer, D., et al., Nature Nanotechnology, 2007). While primary amines are critical for the structural and functional integrity of biomolecules, they are not therapeutic targets themselves; rather, they are chemical sites utilized for the engineering of advanced therapeutics. Consequently, the description provided refers to a chemical conjugation process rather than a biological receptor or enzyme target.

Other names

Amino groupN-terminal amineLysine epsilon-amino groupPrimary amino groupAmine-functionalized ligand

The primary amine group acts as a nucleophile that performs an acylation reaction on the N-hydroxysuccinimide (NHS) ester. This nucleophilic attack results in the displacement of the NHS leaving group and the formation of a stable, covalent amide bond between the polymer (PLA-PEG) and the ligand or protein (Hermanson, G. T., Bioconjugate Techniques, 2013).