Preparation of carboxyl- and NHS-activated surfaces

Soak in fresh piranha soluhon (concentrated sulfuric acid hydro-gen peroxide, 2 1 v/v). 

Soak slides with stirring in 3-aminopropyltrimethoxysilane (APS) solution (APS water ethanol, 2 3 95 v/v) for 2 hr. 

Soak amine slides in saturated solution of glutaric acid in DMF overnight rinse thoroughly with DMF. Amine slides have now been converted to carboxyl slides. 

Soak carboxyl slides in a soluhon containing 1 M each NF4S and DCC (N,N -dicyclohexylcarbodiimide) in DMF solvent for 1 hr rinse with DMF. The carboxyl slides have now been converted to the activated NBS slides. 

This protocol was described for immediate use. Otherwise, 1 recommend that the N14S slides be dried under an argon stream, sealed and stored at 4°C rmtil needed for printing. Always allow slides to warm to room temperature before opening to avoid moisture condensation that can inactivate the surface chemistry. 

---