Salmonella infection in food is the one of the major causes of foodborne illnesses including fever, abdominal pain, diarrhea, and nausea. Thus, early detection of Salmonella contamination is important for our healthy life. Conventional detection methods for the food contamination have limitations in sensitivity and rapidity, thus the early phase detection has been difficult. Herein, we developed a bioelectronic nose using a carbon nanotube (CNT) field-effect transistor (FET) functionalized with Drosophila odorant binding protein (OBP)-derived peptide for easy and rapid detection of Salmonella contamination in food. 3-Mehyl-1-butanol is known as a specific volatile organic compound, which is generated from the food contaminated by Salmonella.
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Briefly, AZ5214 photoresist (PR) was used to fabricate a pattern on a SiO2 wafer. The wafer was dipped into octacyltrichlorosilane (OTS) solution (OTS:hexane = 1:500) for 7 min. The wafer was rinsed with hexane, acetone, and ethanol to remove the PR patterns. The OTS-patterned substrate was incubated in swCNT solution (0.02 mg/ml in 1,2-dichlorobenzene) for 30 s, and CNTs were specifically absorbed to the substrate. Afterward, Pd/Au (10/30 nm) electrodes were fabricated and passivated using PR to protect them from contacting the solution. The Drosophila OBP-derived peptide (TKCVSLMAGTVNKKGEFFFF) was synthesized with purity higher than 90% by Peptron (Korea). The peptide was diluted at 1 μg mL-1 in distilled water and stored at −20 °C. For the immobilization of the peptide, 1.5 μL of peptide solution was placed on the CNT channel and incubated for 4 h at room temperature. After the immobilization process, unbound peptides were washed out 2–3 times with distilled water. Atomic force microscopy (AFM) system (MFP-3D, Asylum Research, USA) was used to analyze the immobilization of the peptide. The pristine CNT channel was imaged at a scan rate of 0.2 Hz. After the peptide immobilization, the CNT channel was imaged again at 0.05
Briefly, AZ5214 photoresist (PR) was used to fabricate a pattern on a SiO2 wafer. The wafer was dipped into octacyltrichlorosilane (OTS) solution (OTS:hexane = 1:500) for 7 min. The wafer was rinsed with hexane, acetone, and ethanol to remove the PR patterns. The OTS-patterned substrate was incubated in swCNT solution (0.02 mg/ml in 1,2-dichlorobenzene) for 30 s, and CNTs were specifically absorbed to the substrate. Afterward, Pd/Au (10/30 nm) electrodes were fabricated and passivated using PR to protect them from contacting the solution. The Drosophila OBP-derived peptide (TKCVSLMAGTVNKKGEFFFF) was synthesized with purity higher than 90% by Peptron (Korea). The peptide was diluted at 1 μg mL-1 in distilled water and stored at −20 °C. For the immobilization of the peptide, 1.5 μL of peptide solution was placed on the CNT channel and incubated for 4 h at room temperature. After the immobilization process, unbound peptides were washed out 2–3 times with distilled water. Atomic force microscopy (AFM) system (MFP-3D, Asylum Research, USA) was used to analyze the immobilization of the peptide. The pristine CNT channel was imaged at a scan rate of 0.2 Hz. After the peptide immobilization, the CNT channel was imaged again at 0.05