4 aminomethylpyridine

A carbon electrode was screen-printed on an overhead projector (OHP) film (Electrodag 423SS, Acheson, Port Huron, MI, USA) using a screen printing machine (BS-860AP, Bando, Seoul, Korea). Monoclonal anti-HA (HA antibody) was kindly donated by HBI (Seoul, Korea). 4-aminomethylpyridine, HA, p-phenylenediamine, sodium nitrite, nickel chloride(Ⅱ) hexahydrate, buffering salts, and other chemicals were purchased from Sigma-Aldrich Co. (Milwaukee, WI, USA). Ammonium disodium pentacyanoamminferrate dehydrate was purchased from Fluka. Phosphate-buffered saline (PBS, 4.3 mM NaH₂PO₄, 15.1 mM Na₂HPO₄, and 140 mM NaCl) and all other solutions were prepared using deionized Milli-Q water (Millipore, Bedford, MA, USA). All chemicals used were of analytical grade.
Poly{3-[6-(1-methylimidazolium-3-yl)alkyl]thiophene-2,5-diyl bromide} (P3HT-imidazole), a conductive polymer, was synthesized following a procedure described in previous papers [32 ,33 ].

4-(Aminomethyl) pyridine, 2-picolylamine, 4-(2-aminoethyl) morpholine, 1-(2-aminoethyl) piperidine, N-(3-dimethylaminopropyl)-N′-ethyl carbodiimide hydrochloride (EDC), hydroxybenzotriazole (HOBt), dimethyl aminopyridine (DMAP), dichloromethane (DCM), n-hexane, ethyl acetate, sodium sulphate, sodium chloride, deuterated chloroform, deuterated dimethyl sulfoxide, deuterium oxide, and Pluronic F-127 were purchased from Sigma-Aldrich. For all aqueous preparations, Milli-Q water was used. Monoolein (MO) and oleic acid (OA) were procured from Nu-chek Prep (GC > 99%), and SN-38 was obtained from Adooq bioscience.

Safranin O (≥85%), tetraethyl orthosilicate (TEOS, 98%), 3-(triethoxysilyl)propylisocyanate (95%) and 4-(aminomethyl)pyridine (4AMP, 98%) were purchased from Sigma-Aldrich (Vienna, Austria). Cetyltrimethylammonium bromide (CTAB, >99%) was purchased from VWR (Vienna, Austria). Solvents were purchased from VWR and Alfa Aesar (Karlsruhe, Germany), and used as received, if not stated otherwise. [Ru(bpy)₂(4AMP)₂](PF₆)₂ (RC1) was synthetized according to the procedure described by our group [23 (link),28 (link)], and [Ru(bpy)₂(PPh₃)Cl]Cl (RC2) was synthetized by following a reported procedure [29 (link)], see Figure S1.