Cantilever sensor for nanomechanical detection of specific protein conformations.

A fast, label-free, and multiplexed method based on piezoresistive cantilevers is reported for the detection of specific protein conformations at the nanoscale level. The ligand-binding domain of the human oestrogen receptor (ER alpha-LBD) is used as the experimental model system, and ER alpha-LBD with or without oestradiol (E2) is detected using the conformation-specific peptides alpha I beta II (Ser-Ser-Asn-His-Gin-Ser-Ser-Arg-Leu-IIe-Glu-Leu-Leu-Ser-Arg, which recognizes E2-bound ER) and alpha I beta II (Ser-Ala-Pro-Arg-Ala-Thr-lie-Ser-His-Tyr-Leu-Met-Gly-Gly, which recognizes E2-free ER). Target-specific signals are obtained in situ at protein concentrations of 2.5-20 nM. The in-build electrical readout of the piezoresistive cantilevers provides a convenient alternative to the conventional optical detection, and the presented method offers the possibility of detecting protein conformational changes using miniaturized microarrays.