Acetic acid

All laboratory wares were soaked in an alkaline detergent (Scat 20X-PF; Nacalai Tesque) overnight, and then rinsed with deionized water. Subsequently, they were soaked in 3 mol L⁻¹ HCl overnight, and then washed again with deionized water. As(iii) standard solution (1000 mg L⁻¹), sodium hydroxide (NaOH), nitric acid (HNO₃, 60%) and acetic acid (AcOH, 99%) were purchased from Kanto Chemical. Sodium acetate (AcONa) was purchased from Nacalai Tesque. ICP multi-element standard solution IV containing 21 elements (Al, Ba, Be, Bi, Ca, Cd, Co, Cu, Fe, Ga, In, K, Li, Mg, Mn, Na, Ni, Pb, Sr, Y, Zn) was purchased from GL science.
The metal concentrations were quantified with inductively coupled plasma optical emission spectrometry (ICP-OES; iCAP 6300; Thermo Fisher Scientific). For pH measurements, a pH meter (Navi F-52; Horiba Instruments) was used. In order to prepare deionized water with a resistivity of > 18.2 MΩ cm, an Arium Pro water purification system (Sartorius Stedium Biotech GmbH) was used. A natural incubator (NIB-82; Iwaki Asahi Techno Glass) was used for heating.

CMC (molecular weight = 8–10 × 10⁴ as specified by manufacturer) with a 0.70 degree of substitution was obtained from Daicel Co., (Osaka, Japan). EGDE was purchased from Fujifilm Wako Pure Chemical Co., Ltd. (Osaka, Japan). Liquid paraffin (Moresco white P-100, 19.04 mm²/s) was purchased from Moresco Co., (Kobe, Japan). Sodium hydroxide was purchased from Kanto Chemical Co., Inc. (Tokyo, Japan). Methanol was purchased from Godo Co., Ltd. (Tokyo, Japan). The SPA was supplied by S. T. Co., (Tokyo, Japan). Trichoderma viride cellulase ONOZUKA R-10 was purchased from Yakult Pharmaceutical Co., Ltd. (Tokyo, Japan). The PBS and sodium acetate buffer used were analytical grade chemicals, i.e., sodium chloride, potassium chloride, sodium dihydrogen phosphate, potassium dihydrogen phosphate, sodium acetate, and acetic acid, purchased from Kanto Chemical Co., Inc. (Tokyo, Japan).

Potassium phosphate monobasic and dibasic, Folin-Ciocalteu’s phenol, xanthine oxidase, xanthine, allopurinol, dimethyl sulfoxide (DMSO), hydrochloric acid, tricholoroacetic acid (TCA), Tween 20, thiobarbituric acid (TBA), proline, sulfosalicylic acid, glacial acetic acid, ninhydrin, and toluene were obtained from Sigma-Aldrich Japan K.K. (Tokyo, Japan). Sodium acetate, acetic acid, aluminium (III) chloride hexahydrate, 1,1-diphenyl-2-picrylhydrazyl (DPPH), dibutyl hydroxytoluene (BHT), and gallic acid were purchased from Kanto Chemical Co. Inc. (Tokyo, Japan). Acetone, potassium peroxodisulfate, 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) were obtained from Nacalai Tesque, Inc. (Kyoto, Japan). Methanol and ethanol at analytical grade were obtained from Junsei Chemical Co.; Ltd. (Tokyo, Japan).

Chitosan (average molecular weight = 1 × 10⁵ according to manufacturer’s data), with a deacetylation degree of 100%, was obtained from Dainichiseika Color & Chemicals Mfg. Co., Ltd. (Tokyo, Japan). Sucrose, sodium periodate, and barium chloride dihydrate were purchased from Fujifilm Wako Pure Chemical Co., Ltd. (Osaka, Japan). NaBH₄ was procured from Tokyo Chemical Industry Co., Ltd. (Tokyo, Japan). Acetate buffer was prepared using analytical-grade sodium acetate and acetic acid purchased from Kanto Chemical Co., Inc. (Tokyo, Japan).

Chemical reagents, namely, methanol, zinc nitrate hexahydrate, 2-methylimidazole, chitosan, and acetic acid were purchased from Kanto Chemical Co., Inc. (Tokyo, Japan). REE nitrate salts such as La(NO₃)₃·6H₂O, Eu(NO₃)₃·6H₂O, and Yb(NO₃)₃·3H₂O were purchased from Kishida Chemical Co., Inc. (Osaka, Japan). The La(III), Eu(III), or Yb(III) ion stock solution was prepared and suitably diluted with ultrapure water. All used reagents used were of analytical grade. During the whole working process, water (>18.2 MΩ) treated by the ultrapure water system (RFU 424TA, Advantech Aquarius, Suite A Dublin, CA, USA) was employed. pH value was measured with the pH meter (HORIBA F-72, Tokyo, Japan).