1 research outputs found
Carbodiimide/NHS Derivatization of COOH-Terminated SAMs: Activation or Byproduct Formation?
COOH-terminated self-assembled monolayers
(SAMs) are widely used
in biosensor technology to bind different amine-containing biomolecules.
A covalent amide bond, however, can be achieved only if the carboxylic
acids are activated. This activation process usually consists of forming
an <i>N</i>-hydroxysuccinimidyl ester (NHS-ester) by consecutively
reacting carboxylic acids with a carbodiimide and NHS. Though many
papers report using this method,ā the experimental conditions vary greatly between them and chemical
characterization at this stage is often omitted. Evidence of an efficient
activation is therefore rarely shown. Furthermore, recent publicationsā have highlighted the complexity of this process, with the possible
formation of different byproducts. In this paper, we have conducted
a study on NHS activation under different conditions with chemical
characterization by polarization-modulation infrared reflectionāabsorption
spectroscopy (PM-IRRAS) and time-of-flight secondary ion mass spectroscopy
(ToF-SIMS). Our results indicate that the nature of the solvent and
carbodiimide and the reactant concentrations play crucial roles in
activation kinetics and efficiency