Highly sensitive detection of multiple proteins from single cells by MoS₂-FET biosensors

Single-cell analysis of proteins is critical to gain precise information regarding the mechanisms that dictate the heterogeneity in cellular phenotypes and their differential response to internal and external stimuli. However, tools that allow sensitive and easy measurement of proteins in individual cells are still limited. The emerging semiconductor-based bioelectronics may provide a new approach to overcome the challenges in this field, however its utility in single-cell protein analysis has not been explored. In this study, we investigated multiple protein detection in single cells by MoS₂ field effect transistors (MoS₂-FETs) modified with specific biological probes. First, β-actin antibody was connected to the surface of MoS₂-FETs by covalent bonds, and the fabricated device was tested using β-actin solution with concentrations from 10^-9 to 10^-3 μg/μL. Next, we examined the application of MoS₂-FET for protein analysis in complex biological samples, and the device showed electrical signal response to human embryonic kidney cell line HEK293T in a dose-dependent manner. Furthermore, we applied this method to analyze individual liver cancer MHCC-97L cells, targeting four cellular proteins, including β-actin, epidermal growth factor receptor, sirtuin-2, and glyceraldehyde-3-phosphate dehydrogenase. The devices modified with corresponding probes could identify the target proteins and showed cell number-dependent responses. As a proof of principle, we demonstrated sensitive and multiplexed detection of proteins in single cells using MoS₂-FETs. The biosensor and this detection method are cost-efficient and user-friendly with broad application prospects in biological studies and clinical diagnosis.