1 5 dan

The fabricated graphene-based device was soaked in a 1 mM solution of 1,5-DAN (Sigma-Aldrich, Bulington, MA, United States) in methanol for 1 h at room temperature and then dipped in a 2% (v/v) solution of GA (Sigma-Aldrich) in phosphate-buffered saline (PBS) in a humid environment for another 6 h. The modified graphene-based device was rinsed several times with PBS and DI water. Finally, the modified device was exposed to 200 μg/mL of MPT64 Ab (Cat. No. ab193435; Abcam, Cambridge, United Kingdom) overnight and washed with PBS and DI water.

DHB was obtained from ProteoChem (Hurricane, HT, USA). 1,5-DAN, formic acid, and trifluoroacetic acid (TFA) were purchased from Sigma-Aldrich (St. Louis, MO, USA). High-performance LC–grade water (H₂O), acetone, methanol, and acetonitrile (ACN) were purchased from Fisher Scientific (Fair Lawn, NJ). BAD5, BFF3, BF35, and SC71 antibodies were purchased as 1-ml supernatants from the Developmental Studies Hybridoma Bank at the University of Iowa (Iowa City, IA); cytochrome c antibody was purchased from Abcam (Cambridge, England). Secondary antibodies Alexa Fluor 488 Goat anti-Mouse IgG1, Alexa Fluor 568 Goat anti-Mouse IgM, and Alexa Fluor 647 Goat anti-Mouse Ig2b were purchased from Life Technologies (Grand Island, NY). 4′,6-Diamidino-2-phenylindole (DAPI) was purchased from Beyotime Biotechnology (Shanghai, China).

2,5-Dihydroxy benzoic acid (2,5-DHB, 160 mg/mL solution in methanol/0.1% TFA 70:30 vol/vol) or 1,5-diaminonaphtalene (1,5-DAN, 20 mg/mL solution in acetonitrile/H₂O 70:30 vol/vol) was deposited using a HTX TM-Sprayer (HTX Technologies, Chapel Hill, NC): flow rate, 90 µL/min; spray nozzle velocity, 1200 mm/min; spray nozzle temperature, 75 °C; nitrogen gas pressure, 10 psi; track spacing, 2 mm; number of passes, 4. 2,5-DHB, 1,5-DAN, and TFA were obtained from Sigma-Aldrich (St. Louis, MO). Methanol, H₂O, and acetonitrile were obtained from Fisher Scientific (Waltham, MA).