The Construction of Layered Architectures of Dendrimers-Adsorption Layers of Amino-terminated Dendrimers on 3-Mercaptopropionic Acid Self-assembled Monolayer Formed on Au

摘要

Adsorption kinetics of amino-terminated poly(amido amine) dendrimer (PAMAM) and poly(trimethyleneimine) dendrimer (PTMI) from aqueous solutions onto 3-mercaptopropionic acid (MPA) self-assembled monolayer (SAM) on Au films have been investigated by surface plasmon resonance sensor and surface enhanced infrared absorption spectroscopy. The adsorption kinetics at high dendrimer concentrations does not obey Langmuir adsorption mechanism but passes 2-step adsorption process, which includes monolayer adsorption and additional adsorption on it. Further consideration indicates the difference on the adsorption structure between two dendrimers: PAMAM dendrimer adsorbs with "the hemi-micellar structure" because of the electrostatic and hydrogen-bonding interactions between amine of PAMAM and carboxylate of MPA SAM, while the adsorption structure of PTMI dendrimer is "the hourglass type" or "the conical type" due to no hydrogen-bonding interaction between dendrimer interior and MPA SAM.