Fig. 7From: Multi-carbon dots and aptamer based signal amplification ratiometric fluorescence probe for protein tyrosine kinase 7 detectiona Fluorescence spectra of the probe in the presence of various cell densities of MCF-7 cells (in range of 1 × 104 to 5 × 105 per mL). b The calibration curve of PTK 7 detection in MCF-7 cells in range of 1 × 104–5 × 105 per mLBack to article page