Abstract
We report on the use of one-dimensional photonic crystals to detect clinically relevant concentrations of the cancer biomarker ERBB2 in cell lysates. Overexpression of the ERBB2 protein is associated with aggressive breast cancer subtypes. To detect soluble ERBB2, we developed an optical set-up which operates in both label-free and fluorescence modes. The detection approach makes use of a sandwich assay, in which the one-dimensional photonic crystals sustaining Bloch surface waves are modified with monoclonal antibodies, in order to guarantee high specificity during the biological recognition. We present the results of exemplary protein G based label-free assays in complex biological matrices, reaching an estimated limit of detection of 0.5 ng/mL. On-chip and chip-to-chip variability of the results is addressed too, providing repeatability rates. Moreover, results on fluorescence operation demonstrate the capability to perform high sensitive cancer biomarker assays reaching a resolution of 0.6 ng/mL, without protein G assistance. The resolution obtained in both modes meets international guidelines and recommendations (15 ng/mL) for ERBB2 quantification assays, providing an alternative tool to phenotype and diagnose molecular cancer subtypes.
Highlights
Over-expression of the human erb-b2 receptor tyrosine kinase 2 (ERBB2) marks the acquisition of growth factor independence by primary and metastatic cancers, and dictates therapeutic ERBB2 blockade by small drugs and antibodies [1]
We present some representative experiments showing the potential of Bloch surface waves (BSW) chips in revealing the ERBB2 in cell lysates at low concentration
After studying the on-chip and chip-to-chip variability of the detection antibody binding step, we focused our attention on the optimization of a cancer biomarker assay for ERBB2 positive and control lysates
Summary
Over-expression of the human erb-b2 receptor tyrosine kinase 2 (ERBB2) marks the acquisition of growth factor independence by primary and metastatic cancers, and dictates therapeutic ERBB2 blockade by small drugs and antibodies [1]. ERBB2 shows very low basal expression in many tissues types, and is involved in normal tissue development and function [4,5]. For this reason, it is clinically important to discriminate extra cellular domain (ECD) ERBB2 levels across a wide range of concentrations, from small to very high
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