A peptide-based antifouling aptasensor for tetracycline analysis

Abstract

Electrochemical sensors are susceptible to fouling caused by the nonspecific adsorption of biomolecules in complex food matrices, which is a major challenge in food safety analyses. Herein, we prepared a new antifouling zwitterionic peptide with the sequence CPPPPKSEKSEKSEE–NH₂ by inserting hydrophilic and neutrally charged serine (S) between alternating lysine (K, positively charged) and glutamic acid (E, negatively charged) residues. The prepared peptide comprising an anchoring domain (–C–), a linker domain (–PPPP–), and an antifouling domain (KSEKSEKSEE–NH₂) exhibited better antifouling performance than CEKEKEKE and CPPPPEKEKEKE. On this basis, an antifouling electrochemical aptasensor was constructed for tetracycline (TC) analyses in milk. The proposed aptasensor showed excellent specificity and stability and had a wide linear range of 0.01–100 ng mL⁻¹ with a low detection limit of 0.0065 ng mL⁻¹ (S/N = 3). Furthermore, the aptasensor was used for assaying TC in milk samples through a simple dilution procedure, and detection results showed good correlation with results obtained through the high-performance liquid chromatography method. This study provides a new strategy for fabricating zwitterionic peptides to construct antifouling sensing platforms for TC detection in food.