PolyAn 3-D NHS (25 pack)

The NHS-ester reacts immediately with the NH2-terminus of biochemical species to form a covalent bond with the surface (420 kJ/mol).

The reaction of carboxyl groups with N-Hydroxy succinimide leads to highly reactive esters, which can be easily reacted with nucleophiles e.g. Amines, Hydrazines. However, due to its high reactivity the NHS-ester is susceptible against hydrolysis and is characterized by a relatively short shelf-life. All NHS-activated surfaces should therefore be processed quickly.

There are a number of different approaches to couple on the NHS surface:

• It is assumed that not all Carboxy groups have reacted to NHS-esters during activation. Thus a negatively charged carboxy surface still remains which in turn supports the physico-chemical adsorption of positively charged probes e.g. NH3. Hence a protonating media (pH < 5) for the biochemical species to get a positive charge is required.

• A nucleophilic attack on the active ester is also catalysed under basic conditions (pH > 8.5). After attachment of the biochemical species the surfaces must be blocked with a blocking buffer containing small molecules that can access all reactive groups within the 3D-Matrix.