Afb1 aptamer

Gold (III) chloride trihydrate (HAuCl₄⋅3H₂O), 6-(Ferrocenyl) hexanethiol (FC6S), Thionin (Thi), 6-mercapto-1-hexanol (MCH), Sodium molybdate dihydrate (Na₂MoO₄-2H₂O), aflatoxin B1 (AFB1), and zearalenone (ZEN) were purchased from MACKLIN Biochemical Co., Ltd. (Shanghai, China). Deoxynivalenol (DON), T-2, aflatoxin G1 (AFG1), aflatoxin M1 (AFM1), and Ochratoxin A (OTA) were purchased from Alta Technology Co., Ltd. (Tianjin, China). The aptamer sequences were selected based on previously reported literature (Yang Y. et al., 2021 (link); Zhu et al., 2021 (link)), which were synthesized by Sangon Biotech Co., Ltd. (Shanghai, China). AFB1 aptamer:
5′-SH-GTTGGGCACGTGTTGTCTCTCTGTGTCTCGTGCCCTTCGCTAGGCCCACA-3′
ZEN aptamer:
5′-SH-TCATCTATCTATGGTACATTACTATCTGTAATGTGATATG-3′
1×TE Buffer and trimethylaminomethane hydrochloride buffer (Tris-HCl) were obtained from Sangon Biotech Co., Ltd. (Shanghai, China). Monolayer graphene oxide (GO) powder was purchased from XFNANO Materials Tech Co., Ltd. (Nanjing, China). Thiourea (CH₄N₂S) and trisodium citrate (C₆H₅Na₃O₇) were purchased from Sinopharm chemical reagent Co., Ltd. (Shanghai, China). The oil samples were obtained from the local supermarket (Zibo, Shandong, China). The remaining chemical reagents used were commercially available in analytical purity, and all solutions were prepared with ultrapure water.

Silver nitrate (AgNO₃) was bought from Shanghai Aladdin Biochemical Technology Co., Ltd. (Shanghai, China). Sodium citrate (Na₃C₆H₅O₇·₂H₂O) was supplied by Shanghai Macklin Biochemical Co., Ltd. (Shanghai, China). (3-Aminopropyl) trimethoxysilane (APTMS) and 4-Aminothiophenol (4-ATP, C₆H₇NS) were bought from Adamas Reagent, Ltd., (Shanghai, China). AFB₁ aptamer (NH₂-5′-GTTGGGCACGTGTTGTCTCTCTGTGTCTCGTGCCCTTCGCTAGGCCCACA-3′) and SH-DNA (HS-5′-CAGAGAGACAACACGTGCCCAAC-3′, partially complementary of AFB₁ aptamer) were bought from Sangon Biotech Co., Ltd. (Shanghai, China). Aluminum foil with a thickness of 0.1 mm and a purity of 99.999% was from Trillion Metals Co., Ltd. (Beijing, China). All other reagents were analytically pure and used without purification. All of the solutions were prepared with ultrapure water (Milli-Q, Merck, Darmstadt, Germany).