DBCO-PEG24-NHS ester is a click chemistry reagent featuring an NHS ester functionality, allowing for specific and efficient covalent bonding with primary amines (such as lysine residue side chains or aminosilane-coated surfaces) under neutral or slightly basic conditions. The hydrophilic polyethylene glycol spacer not only enhances solubility in water but also provides a long and flexible linkage that minimizes steric hindrance during the coupling process. Commonly used in copper-free click chemistry, DBCO-PEG24-NHS ester is available for research purposes only.