Electrochemically Controlled Adsorption of Fc-Functionalized Polymers on β-CD-Modified Self-Assembled Monolayers

Abstract

This work presents an in situ study of the adsorption/desorption behavior of ferrocene(Fc)-functionalized linear polymers on a gold surface covered with beta-cyclodextrin(beta-CD)-modified self-assembled monolayers (SAMs). The characterization of binary SAMs obtained with HS-(CH(2))(11)-EG(6)-N(3) and HS-(CH(2))(11)-EG(4)-OH (EG, ethylene glycol) was performed using a quartz crystal microbalance with dissipation monitoring (QCM-D), cyclic voltammetry, and contact angle measurements. The functionalization of SAMs with beta-CD was made via the "click" reaction between the beta-CD monoalkyne derivative and azide groups exhibited by SAMs. The formation of the host-guest complex between SAM-beta-CD and Fc-derivatized polymers (chitosan (CHI) and poly(allylamine hydrochloride) (PAH)) was studied by QCM-D. The viscoelastic model of Voinova was used to fit QCM-D curves recorded during the adsorption and electrochemically controlled desorption of CHI-Fc and PAH-Fc on SAM-beta-CD. Using QCM-D coupled to cyclic voltammetry, we demonstrated that CHI-Fc and PAH-Fc can be successfully deposited on a SAM-beta-CD-coated gold surface forming a stable multivalent inclusion complex between Fc moieties of polymer and beta-CD cavities of SAM. We also showed that all specifically attached polymer chains can be detached from the SAM-beta-CD-coated gold surface by applying an electric field.

Designing multivalent probes for tunable superselective targeting

“…2 shows that the gold surfaces, which exhibited an initial contact angle of 75 ± 2°, became more hydrophilic after the formation of the pegylated SAM. As expected, the contact angles obtained for the mixed SAMs were intermediate between those of the pure monolayers of each single component (23), and surfaces became more hydrophobic after their click functionalization with hydrophobic guests. Remarkably, the evolution of the contact angles measured after immobilization of adamantane followed exactly the same trend as that obtained for SAM-Fc ( Fig.…”

“…1C). To produce ferrocene-terminated SAMs (SAM-Fc), we subsequently attached ferrocene using an azidealkyne click reaction (16,23). The surface density of ferrocene (Γ Fc ; Fig.…”

“…1 C, 3) was tuned by changing the fraction of the azideterminated thiol in solution, and quantified electrochemically from the anodic charge associated with the conversion of Fc to Fc + ( Fig. 2A, Inset) (16,23). Using this approach, Γ Fc was varied from 0.5 to 330 pmol/cm 2 , corresponding to root-meansquare distances between neighboring ferrocenes (l Fc ) ranging from 18 to 0.7 nm.…”

10 Years of Click Chemistry: Synthesis and Applications of Ferrocene‐Derived Triazoles

“…The CDs were introduced by using click chemistry on preformed SAMs on gold surface; they showed the association and dissociation of ferrocene polymers into CD during the redox process. [69] In parallel, Kang et al reported the binding of a cyclodextrin polymer onto ferrocene-functionalized SAMs on gold electrode. Kang et al carried out atom-transfer radical polymerization (ATRP) on the surface of the gold electrode.…”

Electrochemically and DNA-triggered cell release from ferrocene/β-cyclodextrin and aptamer modified dualfunctionalized graphene substrate

“…Cyclodextrins (CDs) are a class of cyclic oligosaccharides which are widely used for their ability to form inclusion complexes with a large range of substrate molecules [25]. One of the most investigated pairs, β-CD and ferrocene (Fc) has been employed in electroactive macromolecular adhesion with strong binding ability [27,28], involving linear polymers [30,31], dendrimers [32] and nanotubes [33], etc. Furthermore, the host-guest interaction is usually reversible and depending on the redox state of ferrocene [25,27].…”