Protocol A6 by Malvano et al. [42]: Cysteamine, glutaraldehyde, and PAMAM dendrimer scaffold Reagents 20 mM cysteamine solution; 5% (v/v) glutaraldehyde solution; Activation solution: 75 mM N-(3-dimethylaminopropyl)-N-ethylcarbodiimide hydrochloride (EDC) and 15 mM N-hydroxysuccinimide (NHS) in MES buffer; MES buffer: 100 mM 2-(N-morpholino) ethanesulfonic acid, pH 7.4; PAMAM solution (1 mg/mL, 1.5 mg/mL, and 2 mg/mL were investigated, highest sensitivity with 2 mg/mL); 0.5 µM aptamer solution; Phosphate buffer saline (PBS) solution: 137 mM NaCl, 2.7 mM KCl, 8.1 mM Na2HPO4 and 1.47 mM KH2PO4, pH 7.5. Method Drop the cysteamine solution on the cleaned electrode and apply a constant potential of 1.2 V vs. Ag/AgCl for 20 min; Thoroughly rinse with water; Drop 100 µL of glutaraldehyde solution on the electrode and incubate for 1 h; Thoroughly rinse with water; Incubate with the PAMAM solution for 3 h; Treat the aptamer with activation solution for 2 h; Incubate the electrode with the aptamer solution; Rinse with PBS buffer.