Carbodiimide/NHS Derivatization of COOH-Terminated SAMs: Activation or Byproduct Formation?

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• 作者：Francisco Palazon ; Cindy Montenegro Benavides ; Didier L茅onard ; 脡liane Souteyrand ; Yann Chevolot ; Jean-Pierre Cloarec
• 刊名：Langmuir
• 出版年：2014
• 出版时间：April 29, 2014
• 年：2014
• 卷：30
• 期：16
• 页码：4545-4550
• 全文大小：310K
• 年卷期：v.30,no.16(April 29, 2014)
• ISSN：1520-5827

文摘

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 N-hydroxysuccinimidyl ester (NHS-ester) by consecutively reacting carboxylic acids with a carbodiimide and NHS. Though many papers report using this method,1鈭? 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 publications9鈭?1 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 reflection鈥揳bsorption 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.