Lead 2 acetate trihydrate

Lead (II) acetate trihydrate [Pb(CH₃CO₂)₂·3H₂O, ≥99%], sodium sulfide and anhydrous (Na₂S, ≥90%), were purchased from J&K Scientific (China). Ribonuclease-A from bovine pancreas (>70 U/mg), was purchased from Sigma-Aldrich (USA). Type I collagen from cow calcaneal tendon and sodium hydroxide (NaOH, ≥95%) were bought from Shanghai Macklin Biochemical Co., Ltd. Deionized water was utilized as the working solution. The procedure of microwave synthesis was done with microwave reactor Discover SP (CEM, USA). The NIR-II FL images were obtained from the Artemis Intelligent Imaging system (Shanghai Hengguang Zhiying Medical Technology Co., Ltd.) with 808 nm of excitation source provided by two fiber-coupled lasers. NIR long-pass filter of 1250 nm was used and emitted FL signal was caught by InGaAs camera NIRvana 640 (Princeton, USA).

Ionic liquids, including 1-ethyl-3-methylimidazolium tetrafluoroborate ([Emim]BF₄, >99%), 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF₄, >99%), 1-octyl-3-methylimidazolium tetrafluoroborate ([Omim]BF₄, >99%), and 1-hexyl-3-methylimidazolium tetrafluoroborate ([Hmim]BF₄, >99%) were purchased from the Centre of Green Chemistry and Catalysis, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences. Polyethylene glycol (PEG-200, >99%), thiourea (>99%), lead(ii) acetate trihydrate (>99%), tetrabutylammonium tetrafluoroborate ([TBA]BF₄, >99%), and tetrabutylphosphonium tetrafluoroborate ([TPA]BF₄, >99%) were supplied by J&K Scientific Co., Ltd. Nafion D-521 dispersion (5% w/w in water and 1-propanol, ≥0.92 meg g^–1 exchange capacity), Nafion N-117 membrane (0.180 mm thick, ≥0.90 meg g^–1 exchange capacity), and Toray Carbon Paper (CP, TGP-H-60, 19 × 19 cm) were purchased from Alfa Aesar China Co., Ltd.