Polyacrylonitrile

The species of the pufferfish used in this experiment is Takifugu obscurus, which was purchased from Jiangsu Zhongyang Company (Nantong, China). The weight of the pufferfish was about 250g. Medical stainless steel wires (0.5 × 2.5 cm) were purchased from Guangdong Longxin Co. (Zhongshan, China). Graphene oxide (GO) powder (>98 wt%) was purchased from 3A Chemicals Co. (Shanghai, China). Polyacrylonitrile (PAN, average Mw 85000), norepinephrine (NE, 98%), and glacial acetic acid (analytical purity) were purchased from Macklin Co. (Shanghai, China). N,N-dimethylformamide (DMF, analytical purity), tetrodotoxin (≥99%), and methanol (chromatographic grade) were purchased from Aladdin Reagent Co. (Shanghai, China). Tris(hydroxymethyl)amine (TRIS, ≥99%) was purchased from Solarbio Co. (Beijing, China). And ultrapure water was prepared by the water purifier purchased from Chengdu Haokang Technology Co. (Chengdu, China).

Polyacrylonitrile (PAN, M_w = 85 000), poly(vinyl pyrrolidone) (PVP, M_w = 1 300 000), N,N-dimethylformamide (DMF), polyethyleneimine (PEI, M_w = 10 000, 99%), tetraethylenepentamine (TEPA, 95%), ethylene glycol, methyl orange (MO, 98%), sodium hydroxide (NaOH) were all bought from Macklin Biochemical Co., Ltd. HCl (36–38 wt%) was provided by Guangzhou Chemical Reagent Factory. All chemicals were used as received. Deionized (DI) water produced by a Water Purification System (UPT-11-20T) was used throughout this work.