Stability Modification of SPR Silver Nano-Chips by Alkaline Condensation of Aminopropyltriethoxysilane

Abstract

The Silver SPR chip was modified by alkaline-silane condensation with aminopropyltriethoxysilane (APTES) in NaOH aqueous solution at different times. Silver sputtered slides coated with APTES were immersed in NaOH solution, enabling us to produce silver surfaces homogeneously covered with APTES. The surface properties of grafted APTES on sputtered silver surface as a occasion of time were studied using SPR analysis, AFM and contact angle measurement. The mechanical and chemical stability of samples was assayed by tape test and NaCl test. The answers show that hydrolysis and condensation of APTES are activated in alkaline solution and lead to formation of a protective APTES layer on the surface of silver. The morphology of APTES on silver surface is a function of coverage density that is altered by changing time. At short times (< 30 min), APTES molecules physically adsorb to the surface leads to weak protection. At higher condensation times, APTES molecules chemically bond to the surface and each other leads to better protection.

Keywords

• Aminopropyltriethoxysilane
• condensation
• Surface plasmon resonance
• Stability