Quantification of a Neurological Protein in a Single Cell Without Amplification

Proteins are key biomolecules that not only play various roles in the living body but also are used as biomarkers. If these proteins can be quantified at the level of a single cell, understanding the role of proteins will be deepened and diagnosing diseases and abnormality will be further upgraded. In this study, we quantified a neurological protein in a single cell using atomic force microscopy (AFM). After capturing specifically disrupted-in-schizophrenia 1 (DISC1) in a single cell onto a microspot immobilizing the corresponding antibody on the surface, force mapping with AFM was followed to visualize individual DISC1. Although a large variation of the number of DISC1 in a cell was observed, the average number is 4.38 × 10³, and the number agrees with the ensemble-averaged value. The current AFM approach for the quantitative analysis of proteins in a single cell should be useful to study molecular behavior of proteins in depth and to follow physiological change of individual cells in response to external stimuli.