Protocol A7 by Cao et al. [13]: Dual-signaling strategy of aptamer-labelling with ferrocene and the intercalation of RuHex Reagents 100 mM Tris-HCl buffer containing 100 mM NaCl and 10 mM TCEP, pH 7.4; 20 µM A-Lys solution in 100 mM Tris-HCl buffer, containing 100 mM NaCl, pH 7.4; Washing buffer: 10 mM Tris-HCl, pH 7.4; 1 mM mercaptohexanol (MCH) solution in 10 mM Tris-HCl; Lysozyme solutions (linear range: 10 pM to 100 nM) in 100 mM Tris-HCl, containing 100 mM NaCl, pH 7.4; High ionic strength solution: 100 mM Tris-HCl containing 140 mM NaCl and 5 mM MgCl2, pH 7.4; Detection solution: 100 mM Tris-HCl containing 10 µM RuHex, 140 mM NaCl and 5 mM MgCl2, pH 7.4; Regeneration solution: 1 µM A-Lys solution in 100 mM Tris–HCl, containing 100 mM NaCl, 1 mM MgCl2, pH 7.4. Method Prepare a 20 µM P-Fc solution in Tris/NaCl/TCEP buffer and incubate for 1 h at RT; Mix the P-Fc and A-Lys solutions and dilute to obtain 2 µM for each ssDNA; Heat to 90 °C for 5 min, gradually cool down to RT, and incubate at 37 °C for 2 h; Incubate the cleaned electrode in the DNA solution for 20 h at RT; Rinse with washing buffer; Incubate with MCH solution for 1 h; Rinse with double-distilled deionized water and washing buffer in sequence. For the bioassay: Incubate with lysozyme solution for 70 min at 37 °C; Rinse with washing buffer; Immerse in the high ionic strength solution for 30 min at RT; Immerse in detection solution for 6 min. For regeneration, immerse the sensor in regeneration solution for 2 h. Rinse with double-distilled deionized water and washing buffer in sequence.