A protein-based electrochemical method for label-free characterization of sequence-specific protein–DNA interactions

Dual-Aptamer Modification Generates a Unique Interface for Highly Sensitive and Specific Electrochemical Detection of Tumor Cells

“…Before surface modification, the GCE (CHI 104 glassy carbon disk working electrode, CH Instruments, Inc.) was precleaned by polishing with 0.3 and 0.05 μm alumina/water slurries until a mirror-like surface was obtained, followed by sonication and extensive washing using distilled water to remove alumina from the electrode surface. 43 The precleaned GCE was oxidized at +1.5 V for 60 s in an aqueous solution containing 2.5% K 2 Cr 2 O 7 and 10% HNO 3 as previously described, 44 and then soaked in 0.02 M phosphate buffered saline (PBS, pH 6.4) containing 0.03 M EDC and 0.01 M NHS at room temperature for 15 min. After removal of excess EDC and NHS, MEAR cell specific aptamers: 0.1 nmol ds-TLS1c, 0.05 nmol ds-TLS1c/0.05 nmol ds-TLS11a, 0.05 nmol ss-TLS1c/0.05 nmol ds-TLS11a, or 0.05 nmol ss-K88/0.05 nmol ds-TBA were applied to the GCE surface, respectively, and incubated at room temperature for 1 h. The unbound aptamers were then washed away using 0.02 M PBS buffer, collected, and the concentration determined using a NanoDrop 2000c UV−vis spectrophotometer (Thermo Scientific) to calculate the immobilization efficiency.…”

“…Before surface modification, the GCE (CHI 104 glassy carbon disk working electrode, CH Instruments, Inc.) was precleaned by polishing with 0.3 and 0.05 μm alumina/water slurries until a mirror-like surface was obtained, followed by sonication and extensive washing using distilled water to remove alumina from the electrode surface . The precleaned GCE was oxidized at +1.5 V for 60 s in an aqueous solution containing 2.5% K 2 Cr 2 O 7 and 10% HNO 3 as previously described, and then soaked in 0.02 M phosphate buffered saline (PBS, pH 6.4) containing 0.03 M EDC and 0.01 M NHS at room temperature for 15 min.…”