Label-free protein assay based on a nanomechanical cantilever array

TLDR

The technique is intended for early, rapid diagnosis of acute myocardial infarction. The study demonstrates continuous, label‑free detection of creatine kinase and myoglobin using a microfabricated cantilever array. Detection is achieved by measuring surface‑stress‑induced deflection of antibody‑functionalized cantilevers, with reference cantilevers correcting for thermal drift and chemical noise. The array achieved sub‑20 µg ml⁻¹ sensitivity for myoglobin, detected both biomarkers independently in complex background, and supports simultaneous measurement of up to seven antigen–antibody pairs.

Abstract

We demonstrate continuous label-free detection of two cardiac biomarker proteins (creatin kinase and myoglobin) using an array of microfabricated cantilevers functionalized with covalently anchored anti-creatin kinase and anti-myoglobin antibodies. This method allows biomarker proteins to be detected via measurement of surface stress generated by antigen–antibody molecular recognition. Reference cantilevers are used to eliminate thermal drifts, undesired chemical reactions and turbulences from injections of liquids by calculating differential deflection signals with respect to sensor cantilevers. The sensitivity achieved for myoglobin detection is below 20 µg ml−1. Both myoglobin and creatin kinase could be detected independently using cantilevers functionalized with the corresponding antibodies, in unspecific protein background. This approach permits the use of up to seven different antigen–antibody reactions simultaneously, including an additional thermomechanical and chemical in situ reference. Applications lie in the field of early and rapid diagnosis of acute myocardial infarction.