A contact angle and ToF-SIMS study of SAM-thiol interactions on polycrystalline gold

作者：Tencer Michal^*; Nie Heng Yong; Berini Pierre

来源：Applied Surface Science, 2011, 257(9): 4038-4043.

DOI：10.1016/j.apsusc.2010.11.171

• SAMs
• Thiols
• Exchange
• Contact angle
• ToF-SIMS
• Gold

A process of chemical differentiation of neighboring Au features on a substrate (for biosensing applications) involves a step, where after electrochemical removal of a self-assembled monolayer (SAM) from one feature, another SAM is deposited onto it by incubation with a different thiol. During this incubation step, other undesorbed features are also exposed to this thiol which may lead to a partial SAM-thiol exhange, the extent of which is a function of time. Here, such surface reactions were followed on polystalline Au in both directions using contact angle measurements and time-of-flight secondary ion mass spectrometry (ToF-SIMS). The thiols involved were dodecanethiol (DDT) which forms SAM promoting adsorption of proteins and 11-mercaptoundecyl)tri(ethylene glycol) (TPEG) whose SAM prevents such adsorption. The surface reactions in both directions cannot be described by a simple pseudo-first-order kinetics. It was found that while the DDT SAM interaction with a TPEG solution leads eventually to a total replacement, the reverse process, TPEG SAM interaction with DDT, leads to no noticeable exchange over the first 3 h and then asymptotically approaches similar to 50% replacement.

• 出版日期2011-2-15