Fabrication of a reusable electrochemical platform based on acid-responsive host-guest interaction with β- cyclodextrin.

A reusable electrochemical glassy carbon electrode (GCE) platform based on the acid-responsive host-guest interaction between β-cyclodextrin (β-CD) and benzimidazole (BM) derivatives was developed. The β-CD can specifically recognize the BM derivative through the acid -responsive host-guest interaction. The electrode was first modified by eletrografting to immobilize a diamine linker (Boc-EDA), resulting in GCEBoc-EDA in which one amine was used for covalent immobilization to the electrode and another Boc protected amine was used to solid-phase synthesis on following step-by-step modifications on the electrode. After deprotection of the Boc group on the GCEBoc-EDA, carbonyldiimidazole (CDI)-activated β-CD was coupled with -NH2 on the electrode to result in GCEβ-CD. Due to the nonspecific interaction, we further improved the GCEβ-CD electrode by introducing immobilized poly(ethylene glycol) methyl ether (PEG-Me) to result in GCEβ-CD/PEG-Me, along with optimized procedures. CV, DPV, and EIS methods were applied for recording the electrochemistry signals. We utilized GCEβ-CD/PEG-Me to investigate the host-guest interaction and found the electrochemical signal exhibited dynamic behavior. The GCEβ-CD/PEG-Me was able to regenerate the β-CD surface more than 20 times after HCl acidic washes. We further investigated the interaction of carbendazim (CBZ), a commonly used fungicide in the agriculture and food industry, and observed a positive electrochemical response. The sensor design has potential applications in ensuring food safety.