N n dimethylformamide (dmf)

The EHL powder was purchased from LongLive Inc. (Shandong province, Jinan, China). Poly(acrylonitrile) (PAN) (M_w~150,000) was purchased from Sigma-Aldrich Inc., St. Louis, MO, USA. N,N-dimethylformamide (DMF) was purchased from Nanjing Chemical Reagent Inc, Nanjing, China.

Sodium carboxymethyl cellulose (CMC−Na, viscosity: 300~800 mPa⋅s) was purchased from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China). Epichlorohydrin (ECH), sodium hydroxide (NaOH), 8-aminoquinoline (AQ), tetrahydrofuran (THF), span 80, liquid paraffin, butyl alcohol, carbon tetrachloride, N,N-dimethylformamide (DMF) and ethylene diamine tetraacetic acid (EDTA) were acquired from Nanjing Chemical Reagent Co., Ltd. (Naning, China). The stock solutions of metal ions were prepared from various metal salts (CuSO₄, Pb(NO₃)₂, AgNO₃, HgSO₄, ZnCl₂, CdSO₄, MgSO₄, AlCl₃, CsCl and MnSO₄). All of these reagents were used without further purification. All solutions were prepared with deionized water.

Poly (L-glutamic acid) (γ-PGA-Na) (10 kDa) was purchased from Nanjing Shineking Biotech Co., Ltd. (Jiangsu, China). Cetyltrimethylammonium bromide (CTA-Br) was purchased from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China). Iodomethane, 4-methyl-5-hydroxyethyl thiazole, 1-bromopropane, benzyl bromide, bromomethyl benzoic acid, and fluorescein isothiocyanate (FITC) were purchased from Sigma-Aldrich (St. Louis, MO, USA). All of the organic solvents used, such as dimethyl sulfoxide (DMSO), ethanol, ethyl acetate, and N,N-dimethylformamide (DMF), were purchased from Nanjing Chemical Reagent Co., Ltd. (Nanjing, China). Distilled water was purified by a Millipore Milli Q-Plus system (Millipore, Bedford, MA, USA).