Fabrication of an electrochemical EGFR immunosensor using BSA-templatedPb nanocluster as a biocompatible signaling probe

Detection of epidermal growth factor receptor (EGFR) is of paramount importance in medicalsciences, since it has significant application in cancer diagnosis, drug development, and therapymonitoring1. In this work we introduce a new probe for the development of a sensitive, andselective sandwich-type electrochemical EGFR immunosensor. To design the immunsensor, weemployed streptavidin-coated magnetic beads (MB) as a platform for immobilization of thebiotinylated primary antibody (Ab1), and utilized a newly synthesized bovine serum albumin(BSA)-templated Pb nanocluster (PbNC@BSA), conjugated to secondary antibody (Ab2), as asignaling probe. After sandwiching the target protein between primary and secondary Ab, wedissolved PbNC@BSA into an acid, and recorded square wave anodic stripping voltammetric(SWASV) signal of the Pb ions as an analytical signal for quantification of the EGFR. Theimmunosensor responded linearly towards EGFR within the range of 0.4 ng/mL to 35 ng/mL,with a detection limit of 8 pg/mL. The immunosensor showed a good sensitivity, selectivity,stability, and reproducibility, and proved suitable for direct measurement of EGFR in humanserum samples. We also used the as-synthesizd PbNC@BSA as a fluorescence label for in vitrobioimaging of cancerous HeLa and non-cancerous HUVEC cells. In addition, we investigatedcytotoxicity of PbNC@BSA to cancerous and healthy cells, the results of which show thatPbNC@BSA has considerable cytotoxicity to cancerous cells while exhibits subtle cytotoxicity tohealthy cells. Thus, PbNC@BSA as a metal-based signaling probe is a biocompatible fluorescentprobe for live cell imaging, with possible theraputic applications.

Keywords:

EGFR , Electrochemical sandwich immunosensors , BSA templated Pb nanocluster , Cellimaging , Cytotoxicity