Heroin

Ethylene glycol dimethacrylate (EGDMA, Aldrich, St. Louis, MI, USA) and methacrylic acid (MAA, Aldrich) were distilled in vacuo over boiling chips prior to polymerization. Benzylfentanyl, acetyl-benzylfentanyl (ABF), and benzoyl-benzylfentanyl (BBF) were synthesized as described herein. Fentanyl was synthesized according to the method in reference [23 (link)]. Heroin, cocaine, methamphetamine, and 2,2-azobisisobutyronitrile (AIBN) were purchased from Sigma-Aldrich and used without further purification. The solvents used were HPLC-grade, obtained from VWR (Radnor, PA, USA), and used without further purification.

All reagents were of analytical grade and used as received without further purification. Sodium hydroxide, n-hydroxy-succinimide (NHS), 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC), tris(2-carboxyethyl)phosphine hydrochloride (TCEP), 6-mercapto-1-hexanol (MCH), 2,5-dihydroxybenzoic acid (DHBA), ascorbic acid, caffeine, codeine, heroin, di-sodium hydrogen phosphate, sodium dihydrogen phosphate, potassium dihydrogen phosphate, di-potassium hydrogen phosphate, potassium chloride, sodium chloride, potassium ferricyanide, potassium ferrocyanide, magnesium chloride and calcium chloride were obtained from Sigma-Aldrich (Munich, Germany). A previously reported aptamer,^{39 (link)} 5′AGACAAGGAAAATCCTTCAATGAAGTGGGTCG-3′, which is functionalized with disulfide and amine groups at its 5′ and 3′ terminals respectively was purchased from Faza Pajooh Biotech (Iran). Cocaine was obtained from Iran Drug Control Headquarters (Iran). Morphine was obtained from TEMAD Company (Iran). Double-distilled deionized water was used in all solution preparations.