Lipoic acid or lipoic acid, LA, ALA are organic sulfur compounds derived from caprylic acid. The human body needs it to generate energy for our normal functions. Because of its high affinity, lipoic acid can be used to bind to the surface of metallic particles or film surface through the -S-S bond. It has been widely used for gold nanoparticles and quantum dots surfaces. PEGylated lipoic acid is water soluble and can be used directly in aqueous buffers. generally used in medical research, drug release, nanotechnology and new material research, and cell culture. 
PEG-lipoic acid derivatives contain functional groups that can be used to generate conjugates by conventional chemical methods. These agents can modify peptides and proteins and other materials to produce conjugates and / or increase solubility and stability and reduce immunogenicity.