Urea

l-Cysteine ethyl ester hydrochloride was purchased from Tokyo Kasei Co. (Tokyo, Japan). α-Chymotrypsin (EC 3.4.21.1) type II from bovine pancreas, 3×crystallized from 4× crystallized chymotrypsinogen, dialyzed essentially salt-free and prepared as lyophilized powder, which was 54 U/mg protein determined at 25 °C and pH 7.8 with N-benzoyl-l-tyrosine ethyl ester as a substrate, lysozyme from chicken egg white, l-arginine ethyl ester dihydrochloride and ProteoMass™ peptide MALDI-MS calibration kit were purchased from Sigma-Aldrich Co. (St. Louis, MO, USA). 2,5-Dihydroxybenzoic acid, DMSO, trifluoroacetic acid (TFA) and urea were purchased from Kanto Chemical Co. (Tokyo, Japan). Iodoacetamide (IAM) and 5,5-dithiobis (2-nitrobenzoic acid) (DTNB) were obtained from Nacalai Tesque Inc. (Kyoto, Japan). 2,4,6-Trinitrobenzenesulfonic acid sodium salt dihydrate was obtained from Wako Pure Chemical Industries Ltd. (Osaka, Japan). Standards for size exclusion chromatography were from Bio-Rad (Hercules, CA, USA). All other regents used were of analytical grade.

Hydrogen tetrachloroaurate(III) tetrahydrate (HAuCl₄·4H₂O > 99%), urea (CH₄N₂O > 99.0%), benzylamine (C₇H₉N >98.0%), and 2-naphthol (C₁₀H₈O > 99.0%) were purchased from Kanto Chemical Co. Cinnamyl alcohol (C₉H₁₀O > 97.0%) was purchased from Tokyo Chemical Industry Co. Titanium bis(ammonium lactate) dihydroxide ([CH₃CH(O⁻)CO₂NH₄]₂Ti(OH)₂, 50 wt% in H₂O) solution was purchased from Sigma-Aldrich Co. Irregular-shaped anatase TiO₂ particles (mean particle size = 150 nm, specific surface area = 8.1 m² g⁻¹, A-100, Ishihara Sangyo) and rutile-TiO₂ particles (mean particle size = 80 nm, specific surface area = 18 m² g⁻¹, MT-700B, TAYCA) were used as the TiO₂ supports. All chemicals were used as received without further purification.

Hydrogen tetrachloroaurate(iii) hydrate (HAuCl₄·nH₂O; n = 3.7) from Kojima Chemicals, Japan. Urea (98.0%), ethyl cellulose, and α-terpineol (C₁₀H₁₈O) were acquired from KANTO Chemical Co., Japan. Sodium acetate (CH₃COONa) and sodium sulfate (Na₂SO₄) were obtained from Duksan Pure Chemicals Co. Ltd., South Korea. Fluorine-doped transparent conducting oxide glass (FTO; F-doped SnO₂ glass; 7 Ω sq⁻¹) was acquired from Pilkington, USA. The bacterial culture medium was purchased from Becton Dickinson and Company (NJ, USA). All other chemicals were of analytical grade and used as received. The solutions were prepared from DI water obtained using a PURE ROUP 30 water purification system.