Trisodium citrate dihydrate

Hydrogen tetrachloroaurate(III) tetrahydrate (HAuCl 4 ･4H 2 O, 99.9%), trisodium citrate dihydrate (Na-citÁ2H 2 O, 99%), 4mercaptobenzoic acid (PMBA, >95.0%), tetraethyl orthosilicate (TEOS, 95%), aqueous ammonia solution (NH 3 , 25 wt%), and ethanol (99.5%) were purchased from FUJIFILM Wako Pure Chemical Corporation (Osaka, Japan). Polyethylenimine (PEI, M W : ~25,000 g/mol) was purchased from Sigma-Aldrich (Tokyo, Japan). Water was deionized in advance (>18.2 MX cm).

Isada krill frozen and packed in a 1-kg plastic shrink wrap was purchased from Hamaichi (Wakayama, Japan) and stored in a freezer at -30°C until use. The average mass and length of the krill were 0.07±0.01 g and 18.00±0.65 mm, respectively. Diethyl ether, Folin-Ciocalteu reagent, trisodium citrate dihydrate, copper (II) sulfate pentahydrate, bovine serum albumin (BSA), 1,1-diphenyl-2-picryl-hydrazyl (DPPH), 2,2'-azinobis(3-ethylbenzothaiazoline-6-sulfuric acid) (ABTS), 6-hydroxy-2,5,7,8tetramethylchroman-2-carboxylic acid (Trolox), and potassium persulfate, and uracil were purchased from Wako Pure Chemical Industries (Osaka, Japan). Myoglobin, tri -tyrosine, di-L-phenylalanine, and L-phenylalanyl-L-alanine dihydrate were purchased from Sigma-Aldrich (Tokyo, Japan). Glucose oxidase was purchased from Nacalai Tesque (Kyoto, Japan). Other reagents were of analytical grade.