Cytoplasmic Protein-Powered in situ Fluorescence Amplification for Intracellular Assay of Low-Abundance Analyte

Fluorescence amplification is critical for in situ and real-time detection of intracellular low abundance biological species. However, current intracellular amplification techniques mainly rely on synthetic nucleic acid-based nanodevices, manipulating them in living cells remains challenging. To solve this problem, herein, a new signal amplification concept named cytoplasmic protein-powered in situ fluorescence amplification (CPFA) is proposed. CPFA takes cytoplasmic protein as cell-self power for signal amplification enabling it to operate in living cells. To establish a prototype of CPFA, an amplifiable sensor for hydroxyl radicals (·OH) was designed by entrapping the screened cytoplasmic protein-enhanced fluorophore (PBF1) inside mesoporous silica (MSN) nano-container with ssDNA/PTAD-based signal switch. When encountered with ·OH in living cells, the ssDNA was cleaved to separate PTAD from MSN, liberating multiple copies of the loaded PBF1 to light up the fluorescence. Furthermore, these released PBF1 ...