Inclusion of Bisphenols by a Self-Assembled Monolayer of Thiolated Calix[6]arene on a Gold Surface

Abstract

The molecular recognition of various kinds of bisphenols (BPs) by a self-assembled monolayer (SAM) of thiolated calix[6]arene on a gold electrode was examined using cyclic voltammetry (CV). Based on the inhibitory effect of BPs on the inclusion of hydroquinone (HQ) as a probe bythe surface-confined calix[6]arene, the association constants (Kassoc) of BPs with the immobilized calix[6]arene were estimated. The Kassoc values for BPs with the SAM of thiolated hexasodium calix[6]arenehexasulfonic acid (thioSCX6) were much smaller than those in the free calix[6]arene derivative systems reported previously. The order of the Kassoc values for BPs with thioSCX6 was bisphenol A (BPA) > bisphenol S (BPS) > bisphenol B (BPB) > bisphenol F (BPF). The Kassoc values for BPA and BPS with thioSCX6 were larger than that for BPB, despite the larger hydrophobicity of BPB than that of BPA and BPS. This is probably because the inclusion phenomena in this system are not simply driven by the hydrophobic interaction, but are significantly affected by several steric and structural factors with immobilization of the host. Those are (1) a decrease in flexibility of the SCX6 cavity by the formation of SAM, (2) a decrease in inclusion ability of the SCX6 by the presence of Au surface just beneath it, and (3) a repulsion of hydrophobic guests bythe presence of sulfonate groups at the top of the SAM. Moreover, the association phenomena (adsorption and desorption processes) of a bisphenol with the SCX6 SAM were examined directly by using localized surface plasmon resonance spectroscopy.

Carboxybetaine Polymer‐Protected Gold Nanoparticles: High Dispersion Stability and Resistance against Non‐Specific Adsorption of Proteins

“…[72] The detection of protease, lectin, glycoprotein, etc., was also examined with the help of LSPR. [73][74][75][76][77] In this section, the LSPR technique was adopted to follow the adsorption of proteins to the surface of polymer brushes (PCMB and PMMA) on the gold colloid. Figure 3 clearly indicates that BSA, HSA, lysozyme, and cytochrome c did not adsorb to the surface of the PCMB brush significantly, whereas substantially adsorbed to the surface of both bare gold colloid and PMMA brush.…”

Electrochemical detection of bisphenol A mediated by [Ru(bpy)3]2+ on an ITO electrode

“…Compared with the chemical or biological methods, the electrochemical technique for removing organic pollutants has few or no harmful effects on the environment, it is more independent conditions of wastewater [13,14]. Recently, many attempts have been made to study the electrochemical removal of BPA using various electrodes such as Pt/Ti [15,16], SnO 2 /Ti [17], Au [18], carbon fiber [19,20], and boron-doped diamond [21]. Fenton's reagent generated by an electrochemical technique has been used for the degradation of BPA [22].…”

Developments in Molecular Recognition and Sensing at Interfaces

“…On the basis of the inhibitory effect of bisphenols on the inclusion of hydroquinone by the surface-confined cyclodextrin, the association constants of bisphenols with the immobilized α-cyclodextrin were estimated. Use of β-cyclodextrin [ 73 ] and hexasodium calix[ 6 ]arene hexasulfonic acid [ 74 ] as host structures were also reported by the same research group. Willner and co-workers demonstrated photochemical imprinting of molecular recognition sites for phenoxynaphthacene quinone in SAM assembled on Au surfaces [ 75 ].…”