Caproic acid hexanoic acid

Polystyrene (PS), polymethyl methacrylate (PMMA), and poly(2,6-diphenyl-1,4-phenylene oxide) (known as Tenax) were purchased from Sigma-Aldrich Inc. and GL Science and used for receptor materials. N,N-dimethylformamide (DMF) was purchased from Kanto Chemical Co., Inc. and used as a solvent to prepare solutions of receptor materials for inkjet spotting. Acetic acid (ethanoic acid), propionic acid (propanoic acid), butyric acid (butanoic acid), valeric acid (pentanoic acid), and caproic acid (hexanoic acid) were purchased from Sigma-Aldrich Inc. (Tokyo, Japan), Tokyo Chemical Industry (Tokyo, Japan), FUJIFILM Wako Pure Chemical Corporation (Osaka, Japan), Kanto Chemical Co., Inc. (Tokyo, Japan). All chemicals were used as received. MilliQ water (Merck MilliPore, Tokyo, Japan) was used as water vapor.

β-Lactoglobulin (β-LG), polyethylene glycol with an average molecular weight of 8000 g mol⁻¹ (PEG8000), guanidine hydrochloride (GdHCl), 1,6-hexanediol, 2,2,2-trifluoroethanol (TFE), thioflavin T (ThT), sodium chloride (NaCl), sodium dihydrogen phosphate monohydrate (NaH₂PO₄·H₂O), disodium hydrogen phosphate heptahydrate (Na₂HPO₄·7H₂O), p-nitrophenyl acetate (PNPA), p-nitrophenyl butyrate (PNPB), p-nitrophenyl valerate (PNPV), 2′,7′-dichlorofluorescein diacetate (DCFDA), caproic acid (hexanoic acid), deuterium oxide (D₂O), dextran and sodium acetate trihydrate (CH₃COONa·3H₂O) were used as received from Sigma-Aldrich, U.S.A. β-LG (>90%) contains genetic variants β-lactoglobulins A and B (β-LG A and β-LG B). Dyes 7-(diethylamino)-3-(4-maleimidylphenyl)-4-methyl coumarin (CPM), 5-([4,6-dichlorotriazin-2-yl]amino) fluorescein hydrochloride (5-DTAF) and rhodamine 6G (Rh6G) were all purchased from Sigma-Aldrich, U.S.A. All the chemicals were of the highest grade and were used without any further purification. Phosphate buffer (10 mM, pH 7.4) solutions were prepared using deionized Milli-Q water. Milli-Q water was obtained from a Millipore water purifier system (Milli-Q integral). The concentration of β-LG was 5 μM for CD spectroscopic measurements. For all other characterization studies, the concentration of β-LG was 50 μM.