Lutein

Blackcurrant extract (BCE; ACE40™) standardized based on D3R (148 mg/g) and total anthocyanins (391.26 mg/g) were purchased from JUST The Berries PD Corporation (Los Angeles, CA, USA). The detailed composition of the anthocyanins in BCE is presented in Supplementary Table S1. Lutein was purchased from Acros Organics (Los Angeles, CA, USA). The total anthocyanin content was analyzed using the Health Functional Food Code Test Method 5-59-1, announced by the Ministry of Food and Drug Safety (MFDS) of the Republic of Korea. The content of D3R, D3G, C3R, and C3G in BCE was determined by high-performance liquid chromatography (HPLC)-ultraviolet (UV) using a Waters 2695 HPLC system (Waters, Milford, MA, USA). Briefly, 10 mg of BCE was dissolved in 20 mL of 0.1N HCl and filtered using a 0.45 μm syringe filter. A Jupiter^® 4 µm Proteo 90 Å (250 × 4.6 × 4.6 mm; Phenomenex, Torrance, CA, USA) was used for sample separation. The mobile phase consisted of 5% formic acid as mobile phase A and acetonitrile as mobile phase B. The gradient of the mobile phase B was 0 min, 5%; 5 min, 5%; 25 min, 15%; 26 min, 80%; 35 min, 80%; 36 min, 5%; and 50 min, 5%. Other parameters included a column temperature of 35 °C, an injection volume of 10 μL, a flow rate of 1.0 mL/min, and a detection wavelength of 525 nm UV.

Lutein (90%) was purchased from Acros Organics (Fair Lawn, NJ, USA). Dimethyl sulfoxide (DMSO), methanol (HPLC grade), tetrahydrofuran (HPLC grade), dichloromethane, sodium chloride, disodium hydrogen phosphate, potassium dihydrogen phosphate, MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide), and ammonium chloride (NH₄Cl) were purchased from Fisher Scientific (Fair Lawn, NJ, USA). Sodium dodecyl sulphate (SDS) and polyvinyl alcohol (PVA: MW: 30,000–70,000) were procured from Sigma Aldrich (St. Louis, MO, USA). PLGA (50:50; Mw: 10,000 Da) and PLGA–PEG–biotin (50:50; Mw: 10,000 Da–2000 Da) were purchased from Akina PolySciTech, Inc, West Lafayette, IN, USA. Dulbecco’s modified Eagle medium (DMEM, Gibco’s), Dulbecco’s phosphate-buffered saline (DPBS), Triton-X, and trypsin (TrypLE, Gibco) were purchased from Thermo Fisher Scientific (Fair Lawn, NJ, USA). Cellulose ester dialysis tubing (Biotech grade; Mw: 300 kDa) was procured from Spectrum Laboratories, Inc (Gardena, CA, USA). Fluorescein isothiocyanate (FITC) and 4′,6-diamidino-2-Phenylindole (DAPI) were purchased from Invitrogen, Labelling and Detection, Molecular Probes, ThermoFisher Scientific, (Fair Lawn, NJ, USA). Human retinal pigment epithelial cell line (ARPE-19) was purchased from American Type Culture Collection (ATCC, Manassas, VA, USA).

All the reagents used were of analytical or HPLC grade. Methanol and ethanol (96%) were purchased from Fisher Chemicals (Fair Lawn, NJ, USA). DPPH (2,2-diphenyl-1-picrylhydrazyl), Trolox (6-hydroxy-2,5,7,8-tetramethylchromane-2-carboxylic acid), acetic acid, sodium acetate, TPTZ (2,4,6-tris(2-pyridyl)-s-triazine), hydrochloric acid, iron (III) chloride hexahydrate, Folin-Ciocalteau reagent, sodium carbonate, gallic acid, MES monohydrate, tris(hydroxymethyl)aminomethane, L(+)-ascorbic acid, DL-malic acid, L(+) tartaric acid, β-carotene, vitamin B6, and vitamin E were purchased from Sigma-Aldrich (St. Louis, MO, USA). D(+)-Glucose and D(−)-Fructose were purchased from VWR International (Radnor, PA, USA). Lutein was purchased from Thermo Fisher Scientific (Waltham, MA, USA). Celite was purchased from AppliChem (Darmstadt, Germany). Sodium hydroxide and Acetone were purchased from LabChem (Zelienople, PA, USA). Ultrapure water was obtained from a Synergy^® Water Purification System (MilliporeSigma, Burlington, MA, USA).