Used as a bifunctional linker in surface modification and bioconjugation, particularly in biosensors and electrochemical devices. The thiol group binds strongly to gold and other noble metal surfaces, forming stable self-assembled monolayers (SAMs), while the carboxylic acid terminus allows coupling to amines or alcohols via standard carbodiimide chemistry. This dual functionality enables immobilization of biomolecules such as proteins, peptides, or DNA onto sensor surfaces for diagnostic and analytical applications. Also employed in modifying nanoparticles for targeted delivery and in creating anti-fouling surfaces due to its ability to control surface chemistry and molecular orientation.