A label-free sensitive method for membrane protein detection based on aptamer and AgNCs transfer.

Recently, membrane proteins have been considered as candidate cancer biomarkers and drug targets, due to their important roles in numerous physiological processes. Therefore, a facile, sensitive and quantitative detection of the membrane proteins is crucial for better understanding their roles in cancer cells and further validating their function in clinical research. We report a highly facile and sensitive detection method for membrane proteins on living cells in situ based on membrane protein-triggered release of cytosine (C)-rich single-stranded DNA (ssDNA) sequences, and the subsequent silver nanoclusters (AgNCs) transfer from polymer to C-rich ssDNA. The high-quantum yield and stable DNA-AgNCs allow the accurate detection of membrane proteins with facile operations and a common fluorescence spectrophotometer. The detection of protein tyrosine kinase-7 (PTK7), a membrane protein model, displays a response range from 30pM to 2nM with a detection limit of 12pM. The expression of PTK7 on single Hela cell and CCRF-CEM cell was calculated to be 7.5 × 10-19 mol and 1.8 × 10-18 mol, respectively. Given the simple and facile operation of this method, this detection platform can be applied as a universal strategy for ultrasensitive detection of membrane protein on cell in situ.