O phosphoric acid

L-aspartic acid (Sigma-Aldrich, UK), 1,4-diaminobutane (DAB) (Sigma-Aldrich, ≥99%), cysteamine (CYSE) (Sigma-Aldrich, UK), cystamine (CYS) (Sigma-Aldrich, UK), dimethylformamide (DMF) (VWR International, USA), dimethylsulfoxide (DMSO) (Sigma-Aldrich), o-phosphoric acid (VWR), imidazole (ACS reagent, ≥99%, Sigma-Aldrich), citric-acid*H₂O (ACS reagent, ≥99.9%, VWR), sodium chloride (99–100.5%, Sigma-Aldrich), phosphate buffer saline (PBS) (Tablet, Sigma), D,L-dithiotreitol (DTT) (Sigma), 5,5 dithio bis-(2-nitrobenzoic acid) (Sigma, ≥98%, USA), L-cystein (Sigma, ≥97%, USA), Humidified incubator (Nuaire, USA), 100 mm tissue culture dishes (Orange Scientific, Belgium), 48 well plates (Sigma-Aldrich, USA), low cell binding 96 well plates (Nunc, Denmark), Eagle’s Medium Alfa minimal essential medium (αMEM) (Gibco, USA), fetal bovine serum (FBS, Gibco, USA), L-glutamine (Gibco, USA), penicillin and streptomycin (Gibco, USA), L-ascorbic acid 2-phosphate (Sigma-Aldrich, USA), beta-glycerophosphate (Sigma-Aldrich, USA), dexamethasone (Sigma-Aldrich, USA), WST-1 [2-(4-Iodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium] (Roche, Switzerland), Vybrant DiD (Molecular Probes, USA), 2-Amino-2-Methyl-1-Propanol buffer (Sigma-Aldrich, USA), Alkaline Phosphatase Yellow (pNPP) Liquid Substrate System (Sigma-Aldrich, USA).

Microcrystalline cellulose (MCC) and titanium (IV) isopropoxide (TTIP) were purchased from Merck (Darmstadt, Germany), while o-phosphoric acid (85% w/w), nitric acid (70% w/w) and heptane were acquired from VWR chemicals (Leuven, Belgium). Orange G (OG, C₁₆H₁₀N₂Na₂O₇S₂), also known as Acid Orange 10, was obtained from Acros Organics (Geel, Belgium).

L-aspartic acid (Sigma-Aldrich, Darmstadt, Germany), dimethylformamide (DMF) (VWR International, Radnor, PA, USA), dimethylsulfoxide (DMSO) (Sigma-Aldrich, Darmstadt, Germany), nutrient broth (Fluka Analytical, Charlotte, North Carolina, USA), o-phosphoric acid (VWR International, Radnor, PA, USA), phosphate buffer saline (PBS) (Sigma-Aldrich, Darmstadt, Germany), imidazole (ACS reagent, ≥99%, Sigma-Aldrich, Darmstadt, Germany), citric-acid*H2O (ACS reagent, ≥99.9%, VWR International, Radnor, PA, USA), sodium-chloride (99-100.5%, Sigma-Aldrich, Darmstadt, Germany), minimum essential medium (MEM) (Gibco, Waltham, MA, USA), fetal bovine serum (FBS, Gibco, Waltham, MA, USA), L-glutamine (Gibco, Waltham, MA, USA), non-essential amino acids (NEAA, Gibco, Waltham, MA, USA), penicillin-streptomycin mixture (Gibco, Waltham, MA, USA), trypsin/EDTA (Gibco, Waltham, MA, USA), 2-(4-Iodophenyl)-3-(4-nitrophenyl)-5-(2,4-disulfophenyl)-2H-tetrazolium (WST-1 cell proliferation reagent, Roche, Basel, Switzerland). All the chemicals were of analytical grade and used as received. For the aqueous solutions, ultrapure water (ZeneerPower I Water Purification System, Human Corporation, Seoul, South-Korea) was used.