Nexterion Block E for Nexterion Slide E

After spotting it is important to remove unbound DNA-molecules and buffer substances from the slides by extensive washing to avoid any interference with subsequent hybridization experiments. Consequently, we recommend to block the slides with our Nexterion Block E before the microarray is hybridized.

The blocking solution contains molecules that rapidly react with residual covalent binding sites in both, the printed and unprinted areas of the slide surface. Failure to totally block reactive groups may result in non-specific binding of labelled target and probe molecules to the slide surface.

This potentially irreversible covalent coupling of the labelled target is the first component of the non-specific background problem. The second component is weak adhesive association (hydrophobic or electrostatic) of the labeled target with the slide surface. Both of these cause a fluorescent background, which can be eliminated or substantially decreased through the use of Nexterion Block E. This results in a higher reproduceability and quality.

For blocking arrays printed on Nexterion Slide Es we recommend our 4x Nexterion Block E, which should be diluted 1:4 with water prior to the blocking process.

Blocking solution for Nexterion Slide AL

For blocking arrays printed on Nexterion Slide AL we recommend to treat the exposed aldehyde groups with sodium borohydride (NaBH4) thereby reducing them to hydroxyl groups. The use of the aldehyde blocking solution is described in detail in our manual for the Nexterion Slide AL.

The aldehyde blocking solution for approximately 5 slides contains:

• 1.5 g NaBH₄ (# 07998)

• 450 ml PBS (phosphate buffer silane, # 68723)

• 133 ml 99% ethanol (to reduce bubbling)

Blocking solution for Nexterion Slide A+

After immobilization it is important to remove unbound DNA molecules and buffer substances from the slides by extensive washing to avoid any interference with subsequent hybridization experiments. Additionally, blocking of free functional groups is required to avoid non specific binding. Both is achieved by following one of the two protocols given in the respective manual for processing Nexterion Slide A+. Protocol A is based on a pre-hybridization in the presence of BSA whereas protocol B utilizes blocking with succinic anhydride.

Amino slide pre-hybridization solution (protocol A with pre-hybridization):

• 25 ml Nexterion Hyb

• 25 ml H₂O (# 45742)

• 500 mg BSA (# 90938)

(amount sufficient for up to 5 slides)

Amino slide blocking solution (protocol B with blocking step):

• 5 g succinic anhydride (# 04746)

• 315 ml 1-Methyl-2-pyrrolidone

• 35 ml 0.2 M sodium borate (# 77328)

(amount sufficient for up to 20 slides)