DBCO-acid & DBCO-PEG acid is a versatile molecule that finds applications in drug research and development. It belongs to the class of reactive PEGs, which are a group of polymers with a polyethylene glycol backbone and functional groups that allow for conjugation with a variety of molecules. DBCO-acid & DBCO-PEG acid contains two functional groups, a carboxylic acid group and a dibenzocyclooctyne (DBCO) group, that make it an attractive candidate for drug development. The carboxylic acid group can be used to introduce charged groups or linkers, while the DBCO group can be used for bioconjugation with azide-containing molecules, such as peptides or small molecules.