Lipoamide-dPEG®x-acid

Amount: 100mg

Item Name: Lipoamide-dPEG®12-acid

Item #: 10808

Mol. Wt.: 806.03;

single compound dPEG® Spacer is 48 atoms and 55.5 A

Product Features and Benefits: Designed for nanotechnology applications involving gold or silver nanoparticles, quantum dots and other metal particles, including magnetic. The lipoic acid moiety readily attaches itself to a metal surface (e.g., gold) through the two sulfur atoms, and is much more difficult to remove with reducing agents (e.g., DTT) than mono-thiol compounds; hence, the nanoparticle structure is more stable. The dPEG®x linker imparts water solubility to the nanoparticle or quantum dot as well as all of the other benefits of dPEG®s Several choices of spacers are available to allow the customer to optimize his or her application. m-dPEG®x-lipoamide: The methoxy-capped dPEG®x linker is available for customers who want simply to create a water shell around the nanoparticle/quantum dot or to cap in a co-reaction with the lipoamido-dPEG™x-acid. lipoamido-dPEG®x-acid and lipoamido-dPEG®8-alcohol (PN10814): These compounds are available for customers who need to attach other molecules to the dPEG® linker after attaching to the nanoparticle or quantum dot. Compounds are sold with the lipoic acid moiety oxidized. The lipoic acid moiety may be reduced easily with TCEP (PN10014) or with sodium borohydride to form dihydrolipoic acid (DHLA). Applications Nanotechnology and nanobiotechnology using gold or silver particles or quantum dots are broadly diverse, rapidly expanding areas of study in medical diagnostics, medical therapeutics, and chemistry. Metal particles, however, are not water soluble without further modification. Thiols readily bind to gold surfaces, forming dative bonds, and modification of metal nanoparticles with thiol compounds has been commonly used to form self-assembled monolayers (SAMs) and to modify surfaces for coupling proteins and other molecules to the nanoparticles. Monothiols, however, can be readily removed by compounds such as DTT (Cleland’s Reagent). The disulfide lipoic acid (also known as thioctic acid) has been used to modify metal surfaces. Lipoic acid is much more resistant than monothiols to removal from the metal surface by DTT and similar reagents. The dPEG® linker imparts water solubility. The dPEG® linkers terminating in a propionic acid moiety can be used for coupling to other ligands. The dPEG® linkers terminating in a methoxy group can be used for imparting general water solubility to the metal sphere or to cap a nanoparticle that has been functionalized with the lipoamido-dPEG®x acid. Protocols: A variety of protocols exist in the literature and on various websites for reducing lipoic acid (LA) to dihydrolipoic acid (DHLA). Both Tris(2-carboxyethyl)phosphine (TCEP) and sodium borohydride have been used successfully for reduction of LA to DHLA. For specific procedures, please consult the literature. In general, TCEP reduction is carried out in water or aqueous buffer (excluding phosphate buffer, in which TCEP is unstable) at acidic, neutral, or basic pH, in 3x or greater molar excess to the lipoic acid derivative, using an incubation temperature of 25°C up to 50°C, for about 1-2 hours. Users are cautioned, however, that each reduction procedure must be optimized for the particular lipoic acid derivative being reduced to the corresponding DHLA derivative.

Reference: Greg T. Hermanson. Bioconjugate Techniques, 2nd edition. Elsevier, Inc., Burlington, MA 01803, April 2008 (ISBN-13: 978-0-12-370501-3; ISBN-10: 0-12-370501-0), pages 188-190, 485-497, 924-935. Prime and Whitesides, Self-assembled organic monolayers: model systems for studying adsorption of proteins at surfaces, Science, 1991, 252, 1164-1167. Sapsford, et al. Biosensing with luminescent semiconductor quantum dots. Sensors, 2006, 6, 925-953. Dougan, et al. Enhanced oligonucleotide–nanoparticle conjugate stability using thioctic acid modified oligonucleotides, Nucleic Acids Research, 2007, Vol. 35(11), 3668-3675. Sharma, et al., Toward reliable gold nanoparticle patterning on self-assembled DNA nanoscaffold, J. Am. Chem. Soc. 2008, 130, 7820–7821. Satoh, et al., Simultaneous determination of...