PEG is widely used in biomedical applications, including drug delivery, ADC conjugation, fluorescent labeling and targeted diagnostics, oligonucleotide bioconjugation, and surface modification of proteins and peptides. As compounds, PEGs can also bioconjugate themselves to their targets, to optimize the pharmacokinetics of drug therapeutics by conjugating themselves to the target molecules, or to enhance drug delivery as a surface coating for nanoparticles. PEG will have more medical applications in the future.