Calix[4]arene crown ether as an oriented linker for highly sensitive detection of zinc ions using a peptide probe

Peptides, as the simplest biological recognition elements have been developed as probes to capture multitudinous targets. One important factor in fabricating peptide biochips is to immobilize peptides without losing their activity on a solid phase. To keep them functional, it is necessary to immobilize peptide in an oriented way. Calix[4]arene crown ether (CC) has been used as a protein linker molecule on the solid surface. In this study, calix[4]arene crown ether was self-assembled and modified on a gold surface. The calix[4]arene crown ether monolayer was characterized by EIS and SPR. An elaborately designed peptide probe Ac-CCPGCAAAARRRR-NH2 is employed here for the assay of Zn2+. This tridecapeptide consists of a binding part (CCPGC), spacer (AAAA) and immobilization part (RRRR) to interact with a CC SAM. We compared the sensitivity and the specificity of the linker molecules with those of common attachment agents using a zinc ion binding peptide. The fabricated chip showed a superior sensitivity and a much lower detection limit than those chips prepared by other methods. Thus, the calix[4]arene crown ether chip can be used as a powerful peptide linker with a wide range of applications, including peptide–drug interaction, peptide–cell interaction, and an enzyme activity assay.