Synthesis and Characterization of 4-Amino-TEMPO Conjugates

For synthesis, 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl (4-aimno-TEMPO), triethylamine (TEA), and tetrahydrofuran (THF) were purchased from Sigma-Aldrich (St. Louis, USA). Succinimidyl succinate-poly(ethylene glycol)-succinimidyl succinate (NHS-PEG-NHS, average molecular weight = 3400 g mol⁻¹) was purchased from Laysan Bio, Inc. (Alabama, USA). For inhibition efficiency study, thermal initiator azodiisobutyronitrile (AIBN) and dimethyl sulfoxide (DMSO) were also purchased from Sigma-Aldrich. For polymerization, acrylamide (monomer) and N,N′-methylenebis(acrylamide) (cross-linker) were purchased from Sigma-Aldrich. Triton X-100 was purchased from Fisher Scientific (Fair Lawn, USA). The photoinitiator lithium phenyl-2,4,6-trimethylbenzoylphosphinate (LAP) was prepared by following a published protocol.^{[24 (link),25 ]}